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1

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

PubMed

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

2008-09-01

2

Pulses, patterns and paths: neurobiology of acoustic behaviour in crickets  

Microsoft Academic Search

Crickets use acoustic communication for pair formation. Males sing with rhythmical movements of their wings and the mute females approach the singing males by phonotaxis. Females walking on a trackball rapidly steer towards single sound pulses when exposed to split-song paradigms. Their walking path emerges from consecutive reactive steering responses, which show no temporal selectivity. Temporal pattern recognition is tuned

Berthold Hedwig

2006-01-01

3

Vehicle Speed Estimation Using Acoustic Wave Patterns  

Microsoft Academic Search

We estimate a vehicle's speed, its wheelbase length, and tire track length by jointly estimating its acoustic wave pattern with a single passive acoustic sensor that records the vehicle's drive-by noise. The acoustic wave pattern is determined using the vehicle's speed, the Doppler shift factor, the sensor's distance to the vehicle's closest-point-of-approach, and three envelope shape (ES) components, which approximate

Volkan Cevher; Rama Chellappa; James H. Mcclellan

2009-01-01

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

Directivity pattern measurement of moving acoustic sources  

Microsoft Academic Search

Transportation noise reduction is of major concern of environmental research. As regards the railway, high speed creates new noise sources. This paper describes an acoustic moving sources study. Localization methods using microphones arrays provide the position, acoustic power, and the spectrum of the sources. The proposed method computes the directivity pattern of the sources and gives a time-frequency representation of

F. Poisson; J. C. Valiere; O. Coste

1996-01-01

6

Temporal segmentation of repeating auditory patterns  

Microsoft Academic Search

Investigated the identification of repeating auditory patterns in 2 experiments with 8 university summer school students each. In some cases, the pauses compatibly segmented the pattern elements into stable temporal units (an 8-element pattern segmented by 2). In other cases, the pauses incompatibly segmented the pattern elements into temporal units that varied across repetitions (an 8-element pattern segmented by 3).

Stephen Handel

1973-01-01

7

Habitat-associated and temporal patterns of bat activity in a diverse ...  

Treesearch

Science.gov - We Participate ... However, detailed examinations of acoustic surveys results to investigate temporal patterns of bat activity are rare. ... Because the preliminary surveys were restricted in extent (habitats), number (replicates), and ...

8

Powder agglomeration patterns at acoustic driving observed by sonoluminescence technique  

NASA Astrophysics Data System (ADS)

A sonoluminescence (SL) technique gives a sensitive probe to detect spatial agglomeration patterns produced in powder mixtures subjected to acoustically driven plate. Studies of the surface-integrated SL intensity with increasing driving amplitude yield data about variations of the packing density on the surface of vibrating powders. Imaging of spatial distributions of the SL intensity enables direct measurement of the size of agglomeration patterns. The size of the patterns is found to be ~102 ?m in a 3-?m-sized powder at a driving frequency of about 4 MHz. The distribution of the average sonoluminescence intensity across the pattern is attributed to the density gradient while rapid variations in the SL intensity across the pattern are suggested to give the particle velocity distribution within the pattern. The temporal changes of the SL intensity can be used to study time evolutions of dense powder arrangements.

Korotchenkov, O. A.; Goto, T.

1999-01-01

9

Transduction of temporal patterns by single neurons.  

PubMed

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

Hooper, S L

1998-12-01

10

Deformation analysis with temporal speckle pattern interferometry  

NASA Astrophysics Data System (ADS)

The continual deformation of an object will lead to a temporal speckle pattern. By analyzing this time-dependent speckle pattern the temporal deformations of the object can be obtained. We propose a method for measuring the displacement components caused by deformations using the temporal speckle pattern interferometry (TSPI). By capturing a series of speckle interference patterns related to the object deformations, we can get the fluctuations in the intensity of the interference patterns. Further, the phase maps for whole-field object displacement are calculated with the inversion of the temporal interference intensities by estimating both the average intensity and the modulation. In this way, one can quantitatively measure temporal displacements simply using a conventional electronic speckle pattern interferometry system without phase shifting or a carrier. An elaboration of the TSPI is presented and out-of- plane displacements caused by pressure and thermal deformations are measured.

Li, Xide; Yang, Yizhang; Tao, Gang; Li, Rongxian

2001-02-01

11

Anticipation-based temporal pattern generation  

Microsoft Academic Search

A neural network model of complex temporal pattern generation is proposed and investigated analytically and by computer simulation. Temporal pattern generation is based on recognition of the contexts of individual components. Based on its acquired experience, the model actively yields system anticipation, which then compares with the actual input flow. A mismatch triggers self-organization of context learning, which ultimately leads

DeLiang Wang; Budi Yuwono

1995-01-01

12

Propagation patterns of temporal spikes  

Microsoft Academic Search

In standard EEG recordings, spikes appear as single events characterized mainly by the scalp location of the their peak voltage. The signal-to-noise ratio of raw EEG is usually too high to permit more detailed analysis. We used spike averaging to improve the resolution of interictal spikes in 40 patients with temporal lobe epilepsy. Spikes were identified visually in raw, digitally

Ronald G. Emerson; Christine A. Turner; Timothy A. Pedley; Thaddeus S. Walczak; Mennato Forgione

1995-01-01

13

Pulses, patterns and paths: neurobiology of acoustic behaviour in crickets.  

PubMed

Crickets use acoustic communication for pair formation. Males sing with rhythmical movements of their wings and the mute females approach the singing males by phonotaxis. Females walking on a trackball rapidly steer towards single sound pulses when exposed to split-song paradigms. Their walking path emerges from consecutive reactive steering responses, which show no temporal selectivity. Temporal pattern recognition is tuned to the species-specific syllable rate and gradually changes the gain of auditory steering. If pattern recognition is based on instantaneous discharge rate coding, then the tuning to the species-specific song pattern may already be present at the level of thoracic interneurons. During the processing of song patterns, changes in cytosolic Ca(2+ )concentrations occur in phase with the chirp rhythm in the local auditory interneurone. Male singing behaviour is controlled by command neurons descending from the brain. The neuropil controlling singing behaviour is located in the anterior protocerebrum next to the mushroom bodies. Singing behaviour is released by injection of cholinergic agonists and inhibited by gamma-butyric acid (GABA). During singing, the sensitivity of the peripheral auditory system remains unchanged but a corollary discharge inhibits auditory processing in afferents and interneurons within the prothoracic auditory neuropil and prevents the auditory neurons from desensitisation. PMID:16523340

Hedwig, Berthold

2006-03-08

14

Auditory versus visual learning of temporal patterns  

Microsoft Academic Search

Temporal patterns consisting of Morse code triads were presented as auditory and visual tasks. Thirty-two Ss were tested under both conditions in a balanced design. Auditory patterns were learned consistently more easily than visual ones regardless of order of presentation. The second task was learned more rapidly than the first. The results are interpreted to support an auditory short-term store.

James R. Nazzaro; Jean N. Nazzaro

1970-01-01

15

Temporal patterns in marine mammal sounds from long-term broadband recordings  

Microsoft Academic Search

Recent advances in the technology for long-term underwater acoustic recording provide new data on the temporal patterns of marine mammal sounds. Autonomous acoustic recordings are now being made with broad frequency bandwidth up to 200-kHz sampling rates. These data allow sound recording from most marine mammal species, including, for instance, the echolocation clicks of odontocetes. Large data storage capacity up

John A. Hildebrand; Sean Wiggins; Erin Oleson; Ana Sirovic; Lisa Munger; Melissa Soldevilla; Jessica Burtenshaw

2005-01-01

16

Acoustic Identification and Measurement of Activity Patterns of White Grubs in Soil  

Microsoft Academic Search

Activity patterns of Phyllophaga crinita (Burmeister), Phyllophaga congrua (LeConte), Phyllophaga crassissima (Blanchard), and Cyclocephala lurida (Bland) grubs were monitored with acoustic sensors in small pots of bluegrass, Poa arachnifera Torr, at varying and constant temperatures over multiple-day periods. Experienced listeners readily distinguished three types of sound with distinct differences in frequency and temporal patterns, intensities, and durations. Of 3,000 sounds

Minling Zhang; Robert L. Crocker; Richard W. Mankin; Kathy L. Flanders; Jamee L. Brandhorst-Hubbard

2003-01-01

17

Temporal Patterns of Behavior from the Scheduling of Psychology Quizzes  

ERIC Educational Resources Information Center

|Temporal patterns of behavior have been observed in real-life performances such as bill passing in the U.S. Congress, in-class studying, and quiz taking. However, the practical utility of understanding these patterns has not been evaluated. The current study demonstrated the presence of temporal patterns of quiz taking in a university-level…

Jarmolowicz, David P.; Hayashi, Yusuke; St. Peter Pipkin, Claire

2010-01-01

18

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

19

Mining Temporal Patterns to Improve Agents Behavior: Two Case Studies  

Microsoft Academic Search

We propose two mechanisms for agent learning based on the idea of mining temporal patterns from agent behavior. The first\\u000a one consists of extracting temporal patterns from the perceived behavior of other agents accomplishing a task, to learn the\\u000a task. The second learning mechanism consists in extracting temporal patterns from an agent’s own behavior. In this case, the\\u000a agent then

Philippe Fournier-Viger; Roger Nkambou; Usef Faghihi; Engelbert Mephu Nguifo

2009-01-01

20

Timelines of past events: Reconstructive retrieval of temporal patterns  

PubMed Central

Most naturalistic events are temporally and structurally complex in that they comprise a number of elements and that each element may have different onset and offset times within the event. This study examined temporal information processing of complex patterns of partially overlapping stimulus events by using 2 tasks of temporal processing. Specifically, participants observed a pantomime in which 5 actors appeared on the scene for different periods of time. At test, they estimated the duration each actor was present or reconstructed the temporal pattern of the pantomime by drawing a timeline for each actor. Participants made large errors in the time estimation task, but they provided relatively accurate responses by using the timeline as a retrieval support. These findings suggest that temporal processing of complex asynchronous events is a challenging cognitive task, but that reliance on visuo-spatial retrieval support, possibly in combination with other temporal heuristics, may produce functional approximations of complex temporal patterns.

Carell, Maria G.

2011-01-01

21

Spatio-temporal signal preprocessing for multichannel acoustic echo cancellation  

Microsoft Academic Search

Hands-free full-duplex communication systems require acoustic echo cancelers to reduce echoes. Multichannel sound reproduction enhances realism in virtual reality and multimedia communica­ tion systems. However, in the case of multichannel systems the acoustic echo cancellation problem is challenging because of the non-uniqueness of the solution in the least squares sense. There­ fore, preprocessing techniques are required. Known preprocessing approaches act

Karim Helwani; Sascha Spors; Herbert Buchner

2011-01-01

22

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

23

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.

Noesselt, Tomme; Bergmann, Daniel; Heinze, Hans-Jochen; Munte, Thomas; Spence, Charles

2012-01-01

24

1987 WET DEPOSITION TEMPORAL AND SPATIAL PATTERNS IN NORTH AMERICA  

EPA Science Inventory

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

25

Spatial and Temporal Variability of Cross-Basin Acoustic Ray Paths.  

National Technical Information Service (NTIS)

It was suggested by Munk and Forbes (1989) that climate induced changes in ocean temperature may be monitored by measurements of cross-basin acoustic travel time variability. The feasibility of such a monitoring system depends on the spatial and temporal ...

C. M. Ort

1990-01-01

26

Temporal integration of acoustic stimulation obtained in reflex inhibition in rats and humans  

Microsoft Academic Search

Investigated whether inhibition provided by initial stimuli of various durations conforms to established temporal integration functions. Initial stimuli (S1) were noise bursts varying in duration (2, 20, or 200 msec) and intensity (55 or 85 db). Eliciting stimuli (S2) for 6 Holtzman rats were intense tone bursts, which elicited the acoustic startle reflex, and for 9 19–24 yr old humans

Benjamin M. Dykman; James R. Ison

1979-01-01

27

Finding Spatio-Temporal Patterns in Large Sensor Datasets  

ERIC Educational Resources Information Center

|Spatial or temporal data mining tasks are performed in the context of the relevant space, defined by a spatial neighborhood, and the relevant time period, defined by a specific time interval. Furthermore, when mining large spatio-temporal datasets, interesting patterns typically emerge where the dataset is most dynamic. This dissertation is…

McGuire, Michael Patrick

2010-01-01

28

Incremental Learning of Spatio-temporal Patterns with Model Selection  

Microsoft Academic Search

This paper proposes a biologically inspired incremental learning method for spatio-temporal patterns based on our recently\\u000a reported “Incremental learning through sleep (ILS)” method. This method alternately repeats two learning phases: awake and\\u000a sleep. During the awake phase, the system learns new spatio-temporal patterns by rote, whereas in the sleep phase, it rehearses\\u000a the recorded new memories interleaved with old memories.

Koichiro Yamauchi; Masayoshi Sato

2007-01-01

29

Odor identity influences tracking of temporally patterned plumes in Drosophila  

Microsoft Academic Search

Background  Turbulent fluid landscapes impose temporal patterning upon chemical signals, and the dynamical neuronal responses to patterned\\u000a input vary across the olfactory receptor repertoire in flies, moths, and locusts. Sensory transformations exhibit low pass\\u000a filtering that ultimately results in perceptual fusion of temporally transient sensory signals. For example, humans perceive\\u000a a sufficiently fast flickering light as continuous, but the frequency threshold

Parthasarathy Krishnan; Brian J Duistermars; Mark A Frye

2011-01-01

30

Discovering partial spatio-temporal co-occurrence patterns  

Microsoft Academic Search

Spatio-temporal co-occurrence patterns represent subsets of object-types that are often located together in space and time. The aim of the discovery of partial spatio-temporal co- occurrence patterns (PACOPs) is to find co-occurrences of the object-types that are partially present in the database. Discovering PACOPs is an important problem with many applications such as discovering interactions between animals and identifying tactics

Mete Celtic

2011-01-01

31

Temporal Patterns of Communication in the Workplace  

ERIC Educational Resources Information Center

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

Su, Norman Makoto

2009-01-01

32

Flaw detection using temporal speckle pattern interferometry and thermal waves  

NASA Astrophysics Data System (ADS)

This paper presents a temporal speckle pattern interferometry (TSPI) system which uses thermal waves to detect internal defects. The system allows the measurement of out-of-plane thermoelastic displacements generated when a specimen is locally heated with a temporally modulated CO2 laser. The defects can be detected by observing the perturbations which appear in the induced displacement field. Displacements are determined from the calculation of the optical phase distribution using a temporal phase shifting method and temporal phase unwrapping. The description of the TSPI system is followed by the presentation of experimental results that demonstrate that the detectability of certain type of flaws is improved by the use of thermal waves.

Kaufmann, Guillermo H.; Viotti, Matias R.; Galizzi, Gustavo E.

2004-08-01

33

VizPattern: Interactive Querying of Temporal Patterns by Example  

Microsoft Academic Search

In many domains, visualizations help users identify patterns in tem- poral data. However, being able to see patterns is not enough. For example, after spotting an example of a particular pattern, users often want to see all the instances of this pattern and its varia- tions. However, the simple browsing techniques such as filtering and zooming found in most existing

Jing Jin; Pedro Szekely

34

Acoustical Survey of Methane Plumes on North Hydrate Ridge: Constraining Temporal and Spatial Characteristics.  

NASA Astrophysics Data System (ADS)

While methane plumes associated with hydrate formations have been acoustically imaged before, little is known about their temporal characteristics. Previous acoustic surveys have focused on determining plume location, but as far as we know, multiple, repeated surveys of the same plume have not been done prior to the survey presented here. In July 2008, we acquired sixteen identical surveys within 19 hours over the northern summit of Hydrate Ridge in the Cascadia accretionary complex using the onboard 3.5 and 12 kHz echosounders. As in previous studies, the plumes were invisible to the 3.5 kHz echosounder and clearly imaged with 12 kHz. Seafloor depth in this region is ~600 m. Three distinct plumes were detected close to where plumes were located by Heeschen et al. (2003) a decade ago. Two of the plumes disappeared at ~520 m water depth, which is the depth of the top of the gas hydrate stability as determined from CTD casts obtained during the cruise. This supports the conclusion of Heeschen et al. (2003) that the bubbles are armored by gas hydrate and that they dissolve in the water column when they leave the hydrate stability zone. One of the plumes near the northern summit, however, extended through this boundary to at least 400 m (the shallowest depth recorded). A similar phenomenon was observed in methane plumes in the Gulf of Mexico, where the methane was found to be armored by an oil skin. In addition to the steady plumes, two discrete "burps" were observed. One "burp" occurred approximately 600 m to the SSW of the northern summit. This was followed by a second strong event 300m to the north an hour later. To evaluate temporal and spatial patterns, we summed the power of the backscattered signal in different depth windows for each survey. We present the results as a movie in which the backscatter power is shown in map view as a function of time. The surveys encompassed two complete tidal cycles, but no correlation between plume location or intensity and tides is apparent in the data. Additional analyses will constrain plume strength as a function of water depth. Heeschen et al., GRL, v. 30, 2003.

Kannberg, P. K.; Trehu, A. M.

2008-12-01

35

Rainfall redistribution in a tropical forest: Spatial and temporal patterns  

Microsoft Academic Search

The investigation of throughfall patterns has received considerable interest over the last decades. And yet, the geographical bias of pertinent previous studies and their methodologies and approaches to data analysis cast a doubt on the general validity of claims regarding spatial and temporal patterns of throughfall. We employed 220 collectors in a 1-ha plot of semideciduous tropical rain forest in

Alexander Zimmermann; Beate Zimmermann; Helmut Elsenbeer

2009-01-01

36

Mechanisms mediating the perception of complex acoustic patterns  

NASA Astrophysics Data System (ADS)

Three studies dealing with perception of acoustic repetition for long-duration complex sounds have been completed: (1) repetition of frozen Gaussian noise can be detected for infratonal repetition frequencies from 1 Hz through 20 Hz (repetition frequencies above 20 Hz are tonal). Infratonal repetition might be perceived either through the detection of the reoccurrence of singularities within the acoustic pattern, or through a holistic recognition of the entire pattern. This investigation indicated that a holistic recognition of the complex sound is normally responsible for detection of periodicity, (2) illusory continuity of interrupted tones (pulsation thresholds) have been used to study peripheral auditory mechanisms. The investigators found that illusory continuity also occurs in the infratonal range, requiring revision of the theories of basilar membrane mechanics based on the pulsation threshold paradigm, (3) the investigators demonstrated that frozen noises repeated at infratonal frequencies at one ear (silence at the other ear) are detected by some listeners with much greater clarity than when the other ear receives the signal. Ear advantages of this nature have not been observed with other types of complex sounds, and this finding has some interesting implications for auditory theory.

Warren, Richard M.

1987-08-01

37

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

2012-04-28

38

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

39

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

40

Detecting Multineuronal Temporal Patterns in Parallel Spike Trains  

PubMed Central

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

Gansel, Kai S.; Singer, Wolf

2012-01-01

41

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

2013-03-25

42

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

43

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

44

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

45

Extending Mashups to Visualize Patterns in Temporal Data  

Microsoft Academic Search

Many datasets are now published as streams of time- stamped, geo-encoded events using GeoRSS. To understand patterns within this class of data, we have taken ideas from mashups and extended them to develop new visual components that present live geospatial data in novel ways. The components are interactive, live, linked and contain many novel features for understanding temporal and geospatial

Stephen G. Eick; Andrew Eick; Jesse Fugitt; James E. Heath; Mark Ross

46

Temporal Patterns of TV watching for Portuguese Viewers  

Microsoft Academic Search

Audiometer systems provide enormous amounts of detailed TV watching data. Several relevant and interdependent factors may influence TV viewers' behavior. In this work we focus on the tune factor and derive temporal patterns of TV watching, based on panel data. Clustering base attributes are originated from 1440 binary minute-related attributes, capturing the TV watching status (watch\\/not watch). Since there are

N. Datia; J. Moura-Pires; M. Cardoso; H. Pita

2005-01-01

47

Mechanisms mediating the perception of complex acoustic patterns  

NASA Astrophysics Data System (ADS)

The completed research program has dealt with the mechanisms and principle governing the perception of complex sounds. The main topics studied were: (1) pitch averaging mechanisms for repetition pitch; (2) spectral and temporal mechanisms underlying some novel perceptual effects observed with complex tones mistuned from unison; (3) a comparison of tonal and infratonal auditory induction and their underlying mechanisms; (4) monaural ear advantages for infratonal periodicity detection and its implications for subcortical periodicity processing; and (5) evidence that perception of infratonal periodicity does not depend solely on the recognition of the repetition of singularities, but also involves a holistic pattern recognition.

Warren, Richard M.

1988-09-01

48

Storage of temporal pattern sequence in a network.  

PubMed

Learning of single patterns and a temporal pattern sequence in a network when the coupling coefficients between the network elements change their values according to a definite coupling function is described. In contrast to technical systems (e.g. film, tape) where temporal sequences are often encoded in the storage location, the network stores information only by changing the values of the coupling coefficients. A network of 100 elements was stimulated on an UNIVAC 1100/80 computer. Eight single patterns and a sequence of these patterns were offered at the input of the network. After the learning process the network reproduces every stored pattern as an output signal when only parts of it are fed in. The activity, that is the sum of all output signals, is regulated by an external control signal. By setting that control signal to a suitable value the network is able to reproduce the stored pattern sequence starting from any arbitrary pattern. Lowering the external control signal during that process causes the network to hold the last presented pattern until the external control signal is changed again. It is speculated that the coupling function implemented in the stimulation may be analogous to a characteristic describing the chemical process of cooperative binding. PMID:7059627

Willwacher, G

1982-01-01

49

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

Olsen, A.R.

1989-07-01

50

Use of principle velocity patterns in the analysis of structural acoustic optimization.  

PubMed

This work presents an application of principle velocity patterns in the analysis of the structural acoustic design optimization of an eight ply composite cylindrical shell. The approach consists of performing structural acoustic optimizations of a composite cylindrical shell subject to external harmonic monopole excitation. The ply angles are used as the design variables in the optimization. The results of the ply angle design variable formulation are interpreted using the singular value decomposition of the interior acoustic potential energy. The decomposition of the acoustic potential energy provides surface velocity patterns associated with lower levels of interior noise. These surface velocity patterns are shown to correspond to those from the structural acoustic optimization results. Thus, it is demonstrated that the capacity to design multi-ply composite cylinders for quiet interiors is determined by how well the cylinder be can designed to exhibit particular surface velocity patterns associated with lower noise levels. PMID:17348517

Johnson, Wayne M; Cunefare, Kenneth A

2007-02-01

51

II. Temporal patterns of longitudinal change in aging brain function.  

PubMed

Time-dependent changes in brain activity were assessed in a group of older adults who maintained good physical and cognitive health at years 1, 3, 5, 7, and 9 of the Baltimore Longitudinal Study of Aging neuroimaging study. Each year, these participants underwent PET scans during rest and delayed verbal and figural recognition memory conditions. While memory performance remained stable over the 8 years, both generalized and modality-specific patterns of time-dependent changes in regional cerebral blood flow (rCBF) were found. Many brain regions showed steady, progressive changes in rCBF over the 8 years while others maintained rCBF for a number of years before showing incremental declines or increases in activity. These temporal patterns of change were observed in many regions of the brain, particularly in the frontal and temporal lobes, suggesting that there are distinctive patterns of age-related functional decline and compensatory activity over time. The precise patterns of regional involvement and the temporal dynamics of rCBF change within specific regions vary based on cognitive processing demands. PMID:17178430

Beason-Held, L L; Kraut, M A; Resnick, S M

2006-12-18

52

Spatio-temporal Pattern Mining in Sports Video  

Microsoft Academic Search

\\u000a Sports video is characterized with strict game rules, numerable events and well defined structures. In this paper, we proposed\\u000a a generic framework for spatio-temporal pattern mining in sports video. Specifically, the periodicities in sports video are\\u000a identified using unsupervised clustering and data mining method. In this way sports video analysis never needs priori domain\\u000a knowledge about video genres, producers or

Dong-jun Lan; Yu-fei Ma; Wei-ying Ma; Hong-Jiang Zhang

2004-01-01

53

Temporal and steady state acoustic field in a cell culture well: simulation.  

PubMed

The present study was to understand the true power irradiated to the cell line cultured on a culture well, in relation to the nominal power from ultrasonic transducer, and to characterize the temporal variations of the acoustic pressure exerted on the cell. Numerical simulation was carried out for a typical culture well exposed to 1 MHz continuous ultrasound generated by a circular transducer contact underneath the well. The results showed that the ultrasonic pressure exposed to the cell layer in the well was 6.7 times larger than the nominal pressure of the ultrasonic transducer. The ultrasonic pressure in the transient period rose rapidly and was widely variable, and the temporal peak was even greater than that of the steady state period. This suggests that the cells undergo characteristically different ultrasonic exposure between the transient and the steady state period. PMID:24110092

Choi, Min Joo; Kang, Gwan Suk; Kodama, Tetsuya; Coleman, Andrew J

2013-07-01

54

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

55

Temporal pattern analyses in pairs of neighboring mitral cells.  

PubMed

1. Neighboring mitral cells in the rat olfactory bulb have been previously shown to give similar response profiles to a series of odorants. We now analyze their temporal patterns of activity before and during stimulation to evaluate to what extent soma proximity may act on their temporal correlation and to what extent olfactory stimulation may force two close cells to fire with similar patterns. 2. In anesthetized adult rats, we recorded simultaneously the extracellular single-unit activities of two mitral cells with the use of twin micropipettes with tips separated by less than 40 microns. These activities were recorded before and during stimulation by a series of five odorants. 3. Activities were classified into nine types according to their temporal pattern along the respiratory cycle. These types comprised nonrhythmic patterns and rhythmic ones, the latter being simple or complex. A phase parameter was also calculated to compare the positions of maximal activity within respiratory cycles of pairs of cells that had rhythmic activities. 4. All analyses were made by comparing data from pairs of close cells with data from pairs of control cells obtained by pairing each first cell of all recorded pairs with the second units of all other pairs. Results reveal a probability of similar activity types significantly higher in pairs of close cells than in control ones before stimulation. Odorant stimulation enhances this difference by reducing the probability of similar associations in control pairs. Close cells present similar patterns as frequently before, as during, stimulation; however, the probability of double nonrhythmic firings decreases whereas the probability of double rhythmic ones increases.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1527567

Buonviso, N; Chaput, M A; Berthommier, F

1992-08-01

56

Acoustic temporal modulation detection and speech perception in cochlear implant listeners1  

PubMed Central

The goals of the present study were to measure acoustic temporal modulation transfer functions (TMTFs) in cochlear implant listeners and examine the relationship between modulation detection and speech recognition abilities. The effects of automatic gain control, presentation level and number of channels on modulation detection thresholds (MDTs) were examined using the listeners’ clinical sound processor. The general form of the TMTF was low-pass, consistent with previous studies. The operation of automatic gain control had no effect on MDTs when the stimuli were presented at 65 dBA. MDTs were not dependent on the presentation levels (ranging from 50 to 75 dBA) nor on the number of channels. Significant correlations were found between MDTs and speech recognition scores. The rates of decay of the TMTFs were predictive of speech recognition abilities. Spectral-ripple discrimination was evaluated to examine the relationship between temporal and spectral envelope sensitivities. No correlations were found between the two measures, and 56% of the variance in speech recognition was predicted jointly by the two tasks. The present study suggests that temporal modulation detection measured with the sound processor can serve as a useful measure of the ability of clinical sound processing strategies to deliver clinically pertinent temporal information.

Won, Jong Ho; Drennan, Ward R.; Nie, Kaibao; Jameyson, Elyse M.; Rubinstein, Jay T.

2011-01-01

57

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

58

Detection of spatio-temporal change of ocean acoustic velocity for observing seafloor crustal deformation applying seismological methods  

NASA Astrophysics Data System (ADS)

Our group has developed a system for observing seafloor crustal deformation with a combination of acoustic ranging and kinematic GPS positioning techniques. One of the effective factors to reduce estimation error of submarine benchmark in our system is modeling variation of ocean acoustic velocity. We estimated various 1-dimensional velocity models with depth under some constraints, because it is difficult to estimate 3-dimensional acoustic velocity structure including temporal change due to our simple acquisition procedure of acoustic ranging data. We, then, applied the joint hypocenter determination method in seismology [Kissling et al., 1994] to acoustic ranging data. We assume two conditions as constraints in inversion procedure as follows: 1) fixed acoustic velocity in deeper part because it is usually stable both in space and time, 2) each inverted velocity model should be decreased with depth. The following two remarkable spatio-temporal changes of acoustic velocity 1) variations of travel-time residuals at the same points within short time and 2) larger differences between residuals at the neighboring points, which are one's of travel-time from different benchmarks. The First results cannot be explained only by the effect of atmospheric condition change including heating by sunlight. To verify the residual variations mentioned as the second result, we have performed forward modeling of acoustic ranging data with velocity models added velocity anomalies. We calculate travel time by a pseudo-bending ray tracing method [Um and Thurber, 1987] to examine effects of velocity anomaly on the travel-time differences. Comparison between these residuals and travel-time difference in forward modeling, velocity anomaly bodies in shallower depth can make these anomalous residuals, which may indicate moving water bodies. We need to apply an acoustic velocity structure model with velocity anomaly(s) in acoustic ranging data analysis and/or to develop a new system with a large number of sea surface stations to detect them, which may be able to reduce error of seafloor benchmarker position.

Eto, S.; Nagai, S.; Tadokoro, K.

2011-12-01

59

Melatonin affects the temporal pattern of vocal signatures in birds.  

PubMed

In humans and other animals, melatonin is involved in the control of circadian biological rhythms. Here, we show that melatonin affects the temporal pattern of behavioral sequences in a noncircadian manner. The zebra finch (Taeniopygia guttata) song and the crow of the Japanese quail (Coturnix japonica) are courtship vocalizations composed of a stereotyped sequence of syllables. The zebra finch song is learned from conspecifics during infancy, whereas the Japanese quail crow develops normally without auditory input. We recorded and analyzed the complete vocal activity of adult birds of both species kept in social isolation for several weeks. In both species, we observed a shortening of signal duration following the transfer from a light-dark (LD) cycle to constant light (LL), a condition known to abolish melatonin production and to disrupt circadian rhythmicity. This effect was reversible because signal duration increased when the photoperiod was returned to the previous LD schedule. We then tested whether this effect was directly related to melatonin by removal of the pineal gland, which is the main production site of circulating melatonin. A shortening of the song duration was observed following pinealectomy in LD. Likewise, melatonin treatment induced changes in the temporal structure of the song. In a song learning experiment, young pinealectomized finches and young finches raised in LL failed to copy the temporal pattern of their tutor's song. Taken together, these results suggest that melatonin is involved in the control of motor timing of noncircadian behavioral sequences through an evolutionary conserved neuroendocrine pathway. PMID:22506964

Derégnaucourt, Sébastien; Saar, Sigal; Gahr, Manfred

2012-04-17

60

Temporal patterns in rates of community change during succession.  

PubMed

While ecological dogma holds that rates of community change decrease over the course of succession, this idea has yet to be tested systematically across a wide variety of successional sequences. Here, I review and define several measures of community change rates for species presence-absence data and test for temporal patterns therein using data acquired from 16 studies comprising 62 successional sequences. Community types include plant secondary and primary succession as well as succession of arthropods on defaunated mangrove islands and carcasses. Rates of species gain generally decline through time, whereas rates of species loss display no systematic temporal trends. As a result, percent community turnover generally declines while species richness increases--both in a decelerating manner. Although communities with relatively minor abiotic and dispersal limitations (e.g., plant secondary successional communities) exhibit rapidly declining rates of change, limitations arising from harsh abiotic conditions or spatial isolation of the community appear to substantially alter temporal patterns in rates of successional change. PMID:17479464

Anderson, Kristina J

2007-04-06

61

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

2012-05-04

62

Spatial and temporal patterns of Cenozoic dynamic topography around Australia  

NASA Astrophysics Data System (ADS)

Despite its importance, the spatial and temporal pattern of dynamic topography generated by mantle convective circulation is poorly known. We present accurate estimates of dynamic topography from oceanic basins and continental margins surrounding Australia. Our starting point is measurement of residual depth anomalies on the oldest oceanic floor adjacent to the continental shelf. These anomalies were determined from a combined dataset of ~200 seismic reflection and wide-angle images of well-sedimented oceanic crust. They have amplitudes of between -1 km and +0.5 km, and their spatial variation is broadly consistent with long-wavelength free-air gravity and shallow seismic tomographic anomalies. Along the Northwest Shelf, a regional depth anomaly of -300 to -700 m intersects the adjacent continental shelf. The temporal evolution of this anomaly was determined by analyzing the stratigraphic architecture of an extensive carbonate platform, which fringes the shelf and records a dramatic switch from progradation to aggradation during Neogene times. Three-dimensional seismic mapping calibrated by boreholes was used to calculate water-loaded subsidence histories at rollover points of clinoforms along the shelf. At 9 ± 3 Ma, the rate of subsidence increases from 5 to up 75 m Myr-1, generating a subsidence anomaly of -300 to -700 m. The amplitude of this anomaly varies along the shelf and cannot be generated by glacio-eustatic sea-level variation. Instead, we propose that a regional subsidence episode, which affects both the proximal shelf and the distal oceanic basin, was generated by convective drawdown. By combining our results with other published estimates of uplift and subsidence, a map of Australia, which shows the spatial and temporal pattern of dynamic topography is presented. Most, but not all, of Australia's epeirogeny can be attributed to rapid northward motion of the Australian plate over a pre-existing pattern of convective circulation.

Czarnota, K.; Hoggard, M. J.; White, N.; Winterbourne, J.

2013-03-01

63

Flow analysis of acoustic streaming pattern produced by ultrasonic transducer using stereoscopic PIV  

NASA Astrophysics Data System (ADS)

Quantitative flow fields from the acoustic streaming were measured experimentally using the stereoscopic PIV. The acoustic streaming pattern between the ultrasonic transducer and stationary plate, maximum acoustic streaming velocity, velocity variation at resonance and non-resonance, variation of flow pattern and velocity with gap variation were experimentally verified. The maximum acoustic velocity between the gap in the open channel at resonance and non-resonance was located at the ultrasonic transducer center at radial direction and at the neighborhood of the ultrasonic transducer at axial direction. In the vicinity of the ultrasonic transducer surface, larger average acoustic velocity occurred at the edge of the transducer than at the transducer center at the resonant gap. At non-resonant gap, the maximum acoustic velocity exists toward the edge of the transducer. The turbulent intensity varied with gap size and maximum value existed at the transducer center with radial direction and at surface of the stationary plate or transducer with axial direction. At resonant gaps, there was almost zero radial acoustic streaming velocity at the ultrasonic transducer center and there existed only axial streaming velocity. For axial directions, maximum acoustic streaming velocity was located at z position of -16 mm.

Lee, Dong-Ryul

2013-01-01

64

Different Neurons Population Distribution correlates with Topologic-Temporal Dynamic Acoustic Information Flow  

NASA Astrophysics Data System (ADS)

In this study, we will focus on two aspects of neural interconnections. One is the way in which the information flow is produced, and the other has to do with the neural distribution with specific architectural arrangements in the brain. It is very important to realize that both aspects are related, but it is possible to support in the former that the information flow is not only governed by the number of spikes in the neurons, but by a series of other factors as well. Here we show the role played by GABAergic neurons in acoustic information transmission in the Central Nucleus of Inferior Colliculus (CNIC). We report a neural spatial-temporal cluster distribution, associated with each isofrequency region. With these results, we will shed some light onto the emergence of certain mental properties starting from the neural dynamic interactions.

Riofrio, Walter; Angel Aguilar, Luis

65

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.

2012-01-01

66

Investigating the auditory enhancement phenomenon using behavioral temporal masking patterns  

PubMed Central

A narrowband signal is subjected to less masking from a simultaneously presented notched masker if it is preceded by a precursor that occupies the same spectral region as the masker, a phenomenon referred to as enhancement. The present study investigated (i) the amount of enhancement for the detection of a narrowband noise added to a notched masker, and (ii) masking patterns associated with the detection of tone pips added to the narrowband signal. The resulting psychophysical data were compared to predictions generated using a model similar to the neural adaptation-of-inhibition model proposed by Nelson and Young [(2010b). J. Neurosci. 30, 6577–6587]. The amount of enhancement was measured as a function of the temporal separation between the precursor and masker in Experiment I, and as a function of precursor level in Experiment II. The model captured the temporal dynamics of psychophysical enhancement reasonably well for both the long-duration noise signals and the masking patterns. However, in contrast to psychophysical data which indicated reliable enhancement only when the precursor and masker shared the same levels, the model predicated enhancement at all precursor levels.

Shen, Yi; Richards, Virginia M.

2012-01-01

67

Temporal patterns and mechanisms of epilepsy surgery failure.  

PubMed

Epilepsy surgery is an accepted treatment option in patients with medically refractory focal epilepsy. Despite various advances in recording and localization noninvasive and invasive techniques (including electroencephalography (EEG), magnetic resonance imaging (MRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), magnetoencephalography (MEG), subdural grids, depth electrodes, and so on), the seizure outcome following surgical resection remains suboptimal in a significant number of patients. The availability of long-term outcome data on an increasing number of patients suggests two major temporal patterns of seizure recurrence (early vs. late) that implicate the following two different mechanisms for seizure recurrence: (1) a failure to either define/resect the epileptogenic zone, and (2) the nonstatic nature of epilepsy as a disease through the persistence of proepileptic cortical pathology. We describe the temporal patterns of epilepsy surgery failures and discuss their potential clinical, histopathologic, genetic, and molecular mechanisms. In addition, we review predictors of successful surgical interventions and analyze the natural history of epilepsy following surgical intervention. We hypothesize that the acute/early postoperative failures are due to errors in localizing and/or resecting the epileptic focus, whereas late recurrences are likely due to development/maturation of a new and active epileptic focus (de novo epileptogenesis). PMID:23586531

Najm, Imad; Jehi, Lara; Palmini, Andre; Gonzalez-Martinez, Jorge; Paglioli, Eliseu; Bingaman, William

2013-04-15

68

Detection of acoustic temporal fine structure by cochlear implant listeners: behavioral results and computational modeling.  

PubMed

A test of within-channel detection of acoustic temporal fine structure (aTFS) cues is presented. Eight cochlear implant listeners (CI) were asked to discriminate between two Schroeder-phase (SP) complexes using a two-alternative, forced-choice task. Because differences between the acoustic stimuli are primarily constrained to their aTFS, successful discrimination reflects a combination of the subjects' perception of and the strategy's ability to deliver aTFS cues. Subjects were mapped with single-channel Continuous Interleaved Sampling (CIS) and Simultaneous Analog Stimulation (SAS) strategies. To compare within- and across- channel delivery of aTFS cues, a 16-channel clinical HiRes strategy was also fitted. Throughout testing, SAS consistently outperformed the CIS strategy (p ? 0.002). For SP stimuli with F0 = 50 Hz, the highest discrimination scores were achieved with the HiRes encoding, followed by scores with the SAS and the CIS strategies, respectively. At 200 Hz, single-channel SAS performed better than HiRes (p = 0.022), demonstrating that under a more challenging testing condition, discrimination performance with a single-channel analog encoding can exceed that of a 16-channel pulsatile strategy. To better understand the intermediate steps of discrimination, a biophysical model was used to examine the neural discharges evoked by the SP stimuli. Discrimination estimates calculated from simulated neural responses successfully tracked the behavioral performance trends of single-channel CI listeners. PMID:23333260

Imennov, Nikita S; Won, Jong Ho; Drennan, Ward R; Jameyson, Elyse; Rubinstein, Jay T

2013-01-17

69

Temporally-Patterned Magnetic Fields Induce Complete Fragmentation in Planaria  

PubMed Central

A tandem sequence composed of weak temporally-patterned magnetic fields was discovered that produced 100% dissolution of planarian in their home environment. After five consecutive days of 6.5 hr exposure to a frequency-modulated magnetic field (0.1 to 2 µT), immediately followed by an additional 6.5 hr exposure on the fifth day, to another complex field (0.5 to 5 µT) with exponentially increasing spectral power 100% of planarian dissolved within 24 hr. Reversal of the sequence of the fields or presentation of only one pattern for the same duration did not produce this effect. Direct video evidence showed expansion (by visual estimation ?twice normal volume) of the planarian following the first field pattern followed by size reduction (estimated ?1/2 of normal volume) and death upon activation of the second pattern. The contortions displayed by the planarian during the last field exposure suggest effects on contractile proteins and alterations in the cell membrane’s permeability to water.

Murugan, Nirosha J.; Karbowski, Lukasz M.; Lafrenie, Robert M.; Persinger, Michael A.

2013-01-01

70

Auditory temporal pattern learning in children with speech and language impairments*1  

Microsoft Academic Search

Four children demonstrating speech and language impairments were examined with respect to their ability to learn to identify certain auditory temporal perceptual information. These children listened to six-element temporal patterns and made judgments about the temporal proximity of two of the elements. Subjects listened to the patterns over a number of exposures ranging from 6 to 14, depending on the

D ROBIN; A. ROBIN; J. BRUCE TOMBLIN; ANN KEARNEY; LINDA N. HUG

1989-01-01

71

Ancient Architectural Acoustic Resonance Patterns and Regional Brain Activity  

Microsoft Academic Search

Previous archeoacoustic investigations of prehistoric, megalithic structures have identified acoustic resonances at frequencies of 95-120 Hz, particularly near 110-12 Hz, all representing pitches in the human vocal range. These chambers may have served as centers for social or spiritual events, and the resonances of the chamber cavities might have been intended to support human ritual chanting. We evaluated the possibility

Ian A. Cook; Sarah K. Pajot; Andrew F. Leuchter

2008-01-01

72

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

2013-09-13

73

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.

Dalton, Steven J.; Roff, George

2013-01-01

74

[Geostatistical analysis on temporal patterns of Chilo suppressalis population].  

PubMed

The geostatistical analysis on the temporal patterns of Chilo suppressalis population in the Dingcheng District of Changde City, Hunan Province from 1960 to 2001 indicated that the data series of the total number and the numbers of 1st generation, 2nd generation, and over-wintering larvae from year to year displayed better autocorrelation and prediction, especially for the total number, whose autocorrelation range and degree were 10.3 years and 91.1%, respectively. The data series of generation to generation, 1st generation year to year, 3rd generation year to year, and over-wintering larvae year to year all demonstrated an obvious long-term tendency, especially for overwintering larvae. A remarkable cycle of 3 generations in one year was observed in the population of generation to generation. Omitting certain generation or interposing over-wintering larvae only resulted in a slight change in the autocorrelation of the whole data series generation to generation, while planting system, food, climate, and natural enemies played more important roles in regulating the population dynamics rather than the base number of the larvae. The basic techniques of geostatistics applied in analyzing the temporal dynamics of C. suppressalis population were outlined. PMID:16836100

Yuan, Zheming; Li, Fangyi; Hu, Xiangyue; Zhang, Zhongfei

2006-04-01

75

Temporal patterns of responding in small fixed-ratio schedules  

PubMed Central

Pigeons were exposed to an ascending series of small fixed-ratio schedules from fixed-ratio 1 to 7. Two of those pigeons were later placed on a fixed-ratio 30 schedule. The two primary dependent variables were the postreinforcement pause and the interresponse time. Changes in these variables under small fixed ratios were sometimes opposite to changes reported with large fixed ratios. For example, postreinforcement pauses decreased in length as the fixed-ratio requirement increased from fixed-ratio 1 to fixed-ratio 3. Also, the interresponse times early in the small fixed-ratio schedule were shorter than those immediately preceding reinforcement. These findings question the role of interresponse-time reinforcement in determining temporal patterns of responding under small fixed-ratio schedules. They also suggest that there may be a limited region in which the independent variable, fixed-ratio size, does not operate as previously described.

Crossman, Edward K.; Trapp, Nancy L.; Bonem, Elliott J.; Bonem, Marilyn K.

1985-01-01

76

Time-resolved vibration measurement with temporal speckle pattern interferometry  

NASA Astrophysics Data System (ADS)

Temporal speckle pattern interferometry (TSPI) is an optical measurement procedurefor measuring the displacement of rough technical surfaces. The time-dependent speckle modulation due to optical path difference changes is tracked during the whole displacement of the surface and then evaluated pointwise without referring to neighboring pixels. This feature allows for its use as independent point sensors. This aspect of incremental phase tracking enables TSPI to be used to measure time-resolved mechanical vibrations. It also reduces the deteriorating effect of the decorrelation. Therefore large displacements can be measured. A concept for an inexpensive fiber-optical point sensor was developed and the theoretical accuracy for vibration measurement was investigated. The TSPI measurement of a loudspeaker membrane is compared with a high-precision vibrometer measurement. The first results show good agreement.

Kauffmann, Jochen; Tiziani, Hans J.

2006-09-01

77

Time-resolved vibration measurement with temporal speckle pattern interferometry.  

PubMed

Temporal speckle pattern interferometry (TSPI) is an optical measurement procedurefor measuring the displacement of rough technical surfaces. The time-dependent speckle modulation due to optical path difference changes is tracked during the whole displacement of the surface and then evaluated pointwise without referring to neighboring pixels. This feature allows for its use as independent point sensors. This aspect of incremental phase tracking enables TSPI to be used to measure time-resolved mechanical vibrations. It also reduces the deteriorating effect of the decorrelation. Therefore large displacements can be measured. A concept for an inexpensive fiber-optical point sensor was developed and the theoretical accuracy for vibration measurement was investigated. The TSPI measurement of a loudspeaker membrane is compared with a high-precision vibrometer measurement. The first results show good agreement. PMID:16926897

Kauffmann, Jochen; Tiziani, Hans J

2006-09-10

78

Time-frequency integration characteristics of hearing are optimized for perception of speech-like acoustic patterns.  

PubMed

Several psychoacoustic phenomena such as loudness perception, absolute thresholds of hearing, and perceptual grouping in time are affected by temporal integration of the signal in the auditory system. Similarly, the frequency resolution of the hearing system, often expressed in terms of critical bands, implies signal integration across neighboring frequencies. Although progress has been made in understanding the neurophysiological mechanisms behind these processes, the underlying reasons for the observed integration characteristics have remained poorly understood. The current work proposes that the temporal and spectral integration are a result of a system optimized for pattern detection from ecologically relevant acoustic inputs. This argument is supported by a simulation where the average time-frequency structure of speech that is derived from a large set of speech signals shows a good match to the time-frequency characteristics of the human auditory system. The results also suggest that the observed integration characteristics are learnable from acoustic inputs of the auditory environment using a Hebbian-like learning rule. PMID:23862817

Räsänen, Okko; Laine, Unto K

2013-07-01

79

Use of Fixed-Location, Split-Beam Sonar to Describe Temporal and Spatial Patterns of Adult Fall Chum Salmon Migration in the Chandalar River, Alaska  

Microsoft Academic Search

Fixed-location, split-beam hydroacoustics was used to describe temporal and spatial patterns of upstream-swimming fall chum salmon Oncorhynchus keta in the Chandalar River, a tributary of the Yukon River, Alaska. Split-beam techniques allow for three-dimensional tracking of fish targets as they pass through the sonar beam. Elliptical-beam transducers were deployed from opposite river banks to optimize acoustic coverage and were aimed

David W. Daum; Bruce M. Osborne

1998-01-01

80

Spatial and temporal variation of acoustic backscatter in the STRESS experiment  

NASA Astrophysics Data System (ADS)

Acoustic backscatter measurements were made of the seabed with a bottom mounted, circularly scanning sonar. The placement was at 91 m depth, mid-shelf of Northern California (38° 34'N), site C3 of the experiment STRESS I (1988-1989). Our expectation was that sonar images (70 m radius, 12,000 m 2) would provide a means of observing, over a large field of view, changes in the bottom due to storm-induced sediment transport and due to bioturbation. This expectation was supported in part by towed sonar measurements at 35 kHz over a sandy area in the North Sea, where dramatic spatial variation in the level of the backseattered signal was observed during an Autumn storm on scales of a few km with no concomitant change in sediment grain size [ JACKSONet al. (1986) The Journal of the Acoustical Society of America, 80, 1188-1199]. It appeared possible that storm-driven sediment transport might have been responsible for this patchiness, by altering bottom roughness and by redeposition of suspended material. At the California site, a conventional sonar processing of our data from the STRESS experiment reveals no such dramatic change in backscattered signal level due to storms. The sonar images contain random structures whose time evolution is subtle and difficult to interpret. A much clearer picture of temporal and spatial variations emerges from a processing scheme involving cross-correlation of time-separated acoustic views of the bottom. In effect, the sequence of correlation data images produces a movie in which patches of activity are seen to develop as functions of time. It appears that most of this activity is biological rather than hydrodynamic. A tentative explanation is two-fold. The bottom shear stress might have been considerably greater at the North Sea site (with depth only one-half of the California site). The seafloor at the California site was silty-clayey, and backscatter from such floor is less sensitive to the water-floor interface shape and roughness than it would be to the same parameters of a sandy bottom.

Dworski, J. George; Jackson, Darrell R.

1994-08-01

81

Temporal and Spatial Acoustical Factors for Listeners in the Boxes of Historical Opera Theatres  

NASA Astrophysics Data System (ADS)

Acoustical measurements were conducted in a horseshoe-shaped opera house to clarify the acoustical quality of a sound field for listeners inside the boxes of an historical opera house. In order to investigate the effects of multiple reflections between the walls inside a box and scattering by the heads of people, the location of the receiver and the number of persons in the box were varied. In each configuration, four orthogonal factors and supplementary factors were derived as temporal and spatial factors by analysis of binaural impulse responses. Each factor is compared to that at a typical location in the stalls of the same theatre. An omni-directional sound source was located on the stage to emulate a singer or in the orchestra pit to reproduce the location of the musicians. Thus, in this paper, temporal and spatial factors in relation to subjective evaluation are characterized against changes in the listening conditions inside a box, and procedures for improvement and design methods for boxes are proposed. The main conclusions reached are as follows. As strong reflections from the lateral walls of a hall are screened by the front or side walls of a box for a receiver in a seat deeper in the box, the maximum listening level (LL) in the boxes was observed at the front of the box, and the maximum range of LL values for each box was found to be 5 dB. Concerning the initial time delay gap (?t1), a more uniform listening environment was obtained in boxes further back in the theatre than in one closer to the stage. The subsequent reverberation time (Tsub) lengthens for boxes closer to the stage due to the stage house with its huge volume, and a peak is observed at 1 kHz. For the box at the back, Tsub monotonically decreases with frequency in the same way as in the stalls, and moreover, its values approach those in the stalls. As the contribution of multiple reflections relatively increases for a receiver deeper in the box, the IACC in such positions decreases in comparison with that seen at the front of the box.

Sakai, H.; Ando, Y.; Prodi, N.; Pompoli, R.

2002-11-01

82

The BMP signaling gradient patterns dorsoventral tissues in a temporally progressive manner along the anteroposterior axis  

PubMed Central

Summary Patterning of the vertebrate anteroposterior (AP) axis proceeds temporally from anterior to posterior. How dorsoventral (DV) axial patterning relates to AP temporal patterning is unknown. We examined the temporal activity of BMP signaling in patterning ventrolateral cell fates along the AP axis, using transgenes that rapidly turn ‘off’ or ‘on’ BMP signaling. We show that BMP signaling patterns rostral DV cell fates at the onset of gastrulation, while progressively more caudal DV cell fates are patterned at progressively later intervals during gastrulation. Increased BMP signal duration is not required to pattern more caudal DV cell fates, rather distinct temporal intervals of signaling are required. This progressive action is regulated downstream of, or in parallel to BMP signal transduction at the level of Smad1/5 phosphorylation. We propose that a temporal cue regulates a cell's competence to respond to BMP signaling, allowing the acquisition of a cell's DV and AP identity simultaneously.

Tucker, Jennifer A.; Mintzer, Keith A.; Mullins, Mary C.

2008-01-01

83

Temporal evaluation of fringe patterns with spatial carrier with an improved asynchronous phase demodulation algorithm  

Microsoft Academic Search

A method for temporal evaluation of fringe patterns with a spatial carrier is presented. The proposed technique consists in the recording of the temporal irradiance fluctuations obtained when a linear variation of the set-up sensitivity is introduced. In this way, the use of a spatial carrier introduces a linear temporal carrier frequency. This allows the use of fast and low

J. A. Gómez-Pedrero; J. A. Quiroga; M. Servín

2004-01-01

84

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

85

The temporal pattern of vitellogenin synthesis in Drosophila grimshawi  

SciTech Connect

The temporal pattern of protein production and, in particular, vitellogenin protein synthesis during the sexual maturation of Drosophila grimshawi females has been studied in vivo by briefly feeding the flies with 35S-methionine and 3H-amino acids. The overall level of incorporation was very low in young flies; it then progressively increased to reach a maximum with the onset of sexual maturity at 13-15 days. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses revealed three classes of proteins: those synthesized throughout the age spectrum, which constitute the majority of protein species; proteins synthesized primarily or only in young flies; and proteins synthesized only by the older flies. In this Drosophila species, the three vitellogenins (V1, V2, and V3) appeared to be synthesized in a two-phase pattern. In the first phase, small quantities of V1 and V2 were detected immunologically in the fat body and hemolymph of newly emerged and 1 day-old flies. These proteins did not accumulate in the hemolymph or the ovaries, apparently being unstable proteins. The second phase commenced in early vitellogenesis (7-9 days of age) with synthesis in the fat body of small quantities of V1 and V2, followed by V3 proteins. These proteins were secreted and accumulated in the hemolymph and 24 h later were found in the ovaries. Their quantities increased rapidly and a steady state of synthesis, release into the hemolymph, and uptake by the ovaries was reached by days 13-15. We have estimated that during the steady state of vitellogenin synthesis, a fly can synthesize in 24 h at least 152 micrograms of vitellogenins, which is more than 2% of its body weight, at an average rate of about 6.3 micrograms vitellogenins/h. About 2 micrograms of this are synthesized in the fat body, and about 4 micrograms in the ovaries.

Kambysellis, M.P.; Hatzopoulos, P.; Craddock, E.M. (New York Univ., New York City (USA))

1989-09-01

86

Characterizing temporal patterns in the swimming activity of Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

The locomotion behavior of Caenorhabditis elegans has been studied extensively to understand the respective roles of neural control and biomechanics as well as the interaction between them. In the present study, we suggest a new approach to characterize the temporal patterns in the swimming behavior of the organism. The approach is based on the branching length similarity (BLS) entropy defined on a simple branching network consisting of a single node and branches. The organism's swimming activity is recorded using a charge-coupled device (CCD) camera for 3 h at a rate of 4 frames per second. In each frame, we place 13 points as nodes, those points being distributed at equal intervals along the organism's length. Thus, the organism is represented by 13 nodes and 12 edges between nodes. By using the nodes and edges, we construct two simple networks. One is formed by connecting the center point to all other points, and the other is generated from the angles between edges. The BLS entropy values are calculated as S L for the former network and S ? for the latter. We investigate the distributions of the S L and the S ? values in the phase space of S L — S ? and compare those with the values obtained from a simulated C. elegans generated by using randomly-moving chained particles along a certain angle. The comparison revealed distinctive features of the movement patterns of C. elegans during swimming activity. In addition, we briefly discuss the application of our method to bio-monitoring systems to capture behavioral changes of test organisms before and after chemical treatment at low concentrations.

Choi, Yeontaek; Jeon, Wonju; Kang, Seung-Ho; Lee, Sang-Hee; Chon, Tae-Soo

2012-06-01

87

Temporal Patterns in Diversity Change on Earth Over Time  

NASA Astrophysics Data System (ADS)

Multi-celled animals and plants did not originate until about 600 million years ago. Since then the diversity of life has expanded greatly, but this has not been a monotonic increase. Diversity, as taxonomic variety or richness, is produced by the interaction of origination and extinction. Origination and extinction are almost equally balanced; it has taken 600 million years to accumulate 10 to 30 million living species. With most species life spans in the range of one to fifteen million years most species that have ever originated are extinct and global diversity has “turned over” many times. Paleontologists recognize about 18 short-term events of elevated extinction intensity and diversity loss of sufficient magnitude to warrant the term “mass extinction.” Interestingly, in only one instance, the end-Cretaceous extinction, is there a consensus for the triggering event, but the kill mechanism or mechanisms that caused the widespread death of lineages is not established. We know less about the cause-effect relationships for other events. Recently a 62 million-year periodicity in the fluctuation of diversity has been documented, expressed primarily in the variation of diversity of marine genera that survived 45 million years or less. Analysis of the pattern of diversity change at the finest temporal scale possible suggests that the short-term mass extinctions are superimposed on this regular pattern of diversity fluctuations, rather than causal of them. However, most mass extinctions (14 of 18) occurred during the intervals of general diversity loss. It remains to be seen how origination and extinction interact to produce the periodic fluctuation in diversity.

Bambach, Richard

2007-05-01

88

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.

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

2013-01-01

89

Identification of metal ion solutions using acoustic plate mode devices and pattern recognition  

Microsoft Academic Search

The temperature dependence of acoustic plate mode (APM) devices used as probes for dilute electrolytes is described. Specifically, the probe responses that consist of the frequency change and device loss were studied for dilute aqueous solutions of alkali metal ions. It is shown that by integrating the temperature dependence of the APM probe responses with pattern recognition techniques, valuable information

Reiner Dahint; Zack A. Shana; Fabien Josse; Susan A. Riedel; Michael Grunze

1993-01-01

90

Pattern recognition and tomography using crosswell acoustic data  

SciTech Connect

Measurements of the travel time of acoustic signals transmitted between wells at the Department of Energy Multi-Well Experiment site (MWX) near Rifle, Colorado, are processed and analyzed. Interpretations relevant to sand geometry and continuity have proved possible through inspection of the signal travel time plotted against the coordinates of transmitter and receiver wellbore positions, or against the depth of receiver and ray path inclination. The continuity of several sands between wells is corroborated. A major lenticular sand terminating between wells could be inferred. To explore the possible distortions in tomographic images derived from crosswell data, synthetic tomographs are constructed from computed travel times of signals transmitted through idealized models from stratigraphy thought to be present at the MWX site. The synthetic tomographs, although preserving the general character of the model stratigraphy, are distorted enough that detailed interpretations are not possible. Horizontal distortions predominate in reconstructions of flat-lying stratigraphy. 7 refs., 9 figs.

Albright, J.N.; Terry, D.A.; Bradley, C.R.

1985-01-01

91

Spatio-temporal patterns of precipitation in Serbia  

NASA Astrophysics Data System (ADS)

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

Gocic, Milan; Trajkovic, Slavisa

2013-09-01

92

Acoustically Evoked Different Vibration Pattern Across the Width of the Cochlea Partition  

NASA Astrophysics Data System (ADS)

Using optical low coherence interferometry, the acoustically evoked vibration patterns of the basilar membrane (BM) and reticular lamina (RL) in the first turn of living guinea pigs were measured as function of the radial location. It was demonstrated that the vibration of the BM varied widely in amplitude, but little in phase across the width of the partition, while the RL had a different vibration pattern compared with the BM.

Zha, Dingjun; Chen, Fangyi; Friderberg, Anders; Choudhury, Niloy; Nuttall, Alfred

2011-11-01

93

Objective phonological and subjective perceptual characteristics of syllables modulate spatiotemporal patterns of superior temporal gyrus activity.  

PubMed

Natural consonant-vowel syllables are reliably classified by most listeners as voiced or voiceless. However, our previous research [Liederman, J., Frye, R., Fisher, J.M., Greenwood, K., Alexander, R., 2005. A temporally dynamic context effect that disrupts voice onset time discrimination of rapidly successive stimuli. Psychon Bull Rev. 12, 380-386] suggests that among synthetic stimuli varying systematically in voice onset time (VOT), syllables that are classified reliably as voiceless are nonetheless perceived differently within and between listeners. This perceptual ambiguity was measured by variation in the accuracy of matching two identical stimuli presented in rapid succession. In the current experiment, we used magnetoencephalography (MEG) to examine the differential contribution of objective (i.e., VOT) and subjective (i.e., perceptual ambiguity) acoustic features on speech processing. Distributed source models estimated cortical activation within two regions of interest in the superior temporal gyrus (STG) and one in the inferior frontal gyrus. These regions were differentially modulated by VOT and perceptual ambiguity. Ambiguity strongly influenced lateralization of activation; however, the influence on lateralization was different in the anterior and middle/posterior portions of the STG. The influence of ambiguity on the relative amplitude of activity in the right and left anterior STG activity depended on VOT, whereas that of middle/posterior portions of the STG did not. These data support the idea that early cortical responses are bilaterally distributed whereas late processes are lateralized to the dominant hemisphere and support a "how/what" dual-stream auditory model. This study helps to clarify the role of the anterior STG, especially in the right hemisphere, in syllable perception. Moreover, our results demonstrate that both objective phonological and subjective perceptual characteristics of syllables independently modulate spatiotemporal patterns of cortical activation. PMID:18356082

Frye, Richard E; Fisher, Janet McGraw; Witzel, Thomas; Ahlfors, Seppo P; Swank, Paul; Liederman, Jacqueline; Halgren, Eric

2008-02-14

94

Temporal isolation of surface-acoustic-wave-driven luminescence from a lateral p–n junction using pulsed techniques  

Microsoft Academic Search

The authors report surface-acoustic-wave-driven luminescence from a lateral p–n junction formed by molecular-beam epitaxy regrowth of a modulation doped GaAs\\/AlGaAs quantum well on a patterned GaAs substrate. Pulsed techniques are used to isolate the surface-acoustic-wave-driven emission from any emission due to pick-up of the free-space electromagnetic wave. The luminescence provides a fast probe of the signals arriving at the p–n

J. R. Gell; M. B. Ward; P. Atkinson; S. P. Bremner; D. Anderson; C. E. Norman; M. Kataoka; C. H. W. Barnes; G. A. C. Jones; A. J. Shields; D. A. Ritchie

2008-01-01

95

Patterning of microspheres and microbubbles in an acoustic tweezers.  

PubMed

We describe the construction of an ultrasonic device capable of micro-patterning a range of microscopic particles for bioengineering applications such as targeted drug delivery. The device is formed from seven ultrasonic transducers positioned around a heptagonal cavity. By exciting two or three transducers simultaneously, lines or hexagonal shapes can be formed with microspheres, emulsions and microbubbles. Furthermore, phase control of the transducers allows patterning at any desired position in a controlled manner. The paper discusses in detail direct positioning of functionalised microspheres, emulsions and microbubbles. With the advantages of miniaturization, rapid and simple fabrication, ultrasonic tweezers is a potentially useful tool in many biomedical applications. PMID:23225102

Bernassau, A L; Macpherson, P G A; Beeley, J; Drinkwater, B W; Cumming, D R S

2013-04-01

96

Spatial and temporal patterns of malaria incidence in Mozambique  

PubMed Central

Background The objective of this study is to analyze the spatial and temporal patterns of malaria incidence as to determine the means by which climatic factors such as temperature, rainfall and humidity affect its distribution in Maputo province, Mozambique. Methods This study presents a model of malaria that evolves in space and time in Maputo province-Mozambique, over a ten years period (1999-2008). The model incorporates malaria cases and their relation to environmental variables. Due to incompleteness of climatic data, a multiple imputation technique is employed. Additionally, the whole province is interpolated through a Gaussian process. This method overcomes the misalignment problem of environmental variables (available at meteorological stations - points) and malaria cases (available as aggregates for every district - area). Markov Chain Monte Carlo (MCMC) methods are used to obtain posterior inference and Deviance Information Criteria (DIC) to perform model comparison. Results A Bayesian model with interaction terms was found to be the best fitted model. Malaria incidence was associated to humidity and maximum temperature. Malaria risk increased with maximum temperature over 28°C (relative risk (RR) of 0.0060 and 95% Bayesian credible interval (CI) of 0.00033-0.0095) and humidity (relative risk (RR) of 0.00741 and 95% Bayesian CI 0.005141-0.0093). The results would suggest that additional non-climatic factors including socio-economic status, elevation, etc. also influence malaria transmission in Mozambique. Conclusions These results demonstrate the potential of climate predictors particularly, humidity and maximum temperature in explaining malaria incidence risk for the studied period in Maputo province. Smoothed maps obtained as monthly average of malaria incidence allowed to visualize months of initial and peak transmission. They also illustrate a variation on malaria incidence risk that might not be related to climatic factors. However, these factors are still determinant for malaria transmission and intensity in the region.

2011-01-01

97

Match Analysis and Temporal Patterns of Fatigue in Rugby Sevens.  

PubMed

Rugby sevens is a rapidly growing sport. Match analysis is increasingly being used by sport scientists and coaches to improve the understanding of the physical demands of this sport. This study investigated the physical and physiological demands of elite men's rugby sevens, with special reference to the temporal patterns of fatigue during match-play. Nine players, four backs and five forwards (age 25.1±3.1 yrs) participated during two "Roma 7" international tournaments (2010 and 2011). All players were professional level in the highest Italian rugby union, and five of these players also competed at the international level. During the matches (n=15) players were filmed in order to assess game performance. Global positioning system (GPS), heart rate (HR), and blood lactate (BLa) concentration data were measured and analyzed. The mean total distance covered throughout matches was 1221±118m (first half = 643±70m and second half = 578±77m; with a decrease of 11.2%, p>0.05, Effect Size = 0.29). Players achieved 88.3±4.2% and 87.7±3.4% of HR max during the first and second half, respectively. The BLa for the first and second half was 3.9±0.9 mmol·L and 11.2±1.4 mmol·L, respectively. The decreases in performance occurred consistently in the final 3 minutes of the matches (-40.5% in distance covered per minute). The difference found in relation to the playing position, although not statistically significant (p=0.11), showed a large ES (?=0.20), suggesting possible practical implications. These results demonstrate that rugby sevens is a demanding sport that places stress on both the anaerobic glycolytic and aerobic oxidative energy systems. Strength and conditioning programs designed to train these energy pathways may prevent fatigue-induced reductions in physical performance. PMID:23722109

Granatelli, Giampietro; Gabbett, Tim J; Briotti, Gianluca; Padulo, Johnny; Buglione, Antonio; D'Ottavio, Stefano; Ruscello, Bruno

2013-05-29

98

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

99

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

100

Detection of acoustic repetition for very long stochastic patterns.  

PubMed

Guttman and Julesz (1963) employed recycling frozen noise segments (RFNs) as model stimuli in their classic study of the lower limits for periodicity detection and short-term auditory memory. They reported that listeners can hear iteration of these stochastic signals effortlessly as "motorboating" for repetition periods ranging from 50 to 250 msec and as "whooshing" from 250 msec to 1 sec. Both motorboating and whooshing RFNs are global percepts encompassing the entire period, as are RFNs in the pitch range (repetition periods shorter than 50 msec). However, with continued listening to whooshing (but not motorboating) RFNs, individuals hear recurrent brief components such as clanks and thumps that are characteristic of the particular waveform. Experiment 1 of the present study describes a cross-modal cuing procedure that enables listeners to store and then recognize the recurrence of portions of frozen noise waveforms that are repeated after intervals of 10 sec or more. Experiment 2 compares the relative saliencies of different spectral regions in enabling listeners to detect repetition of these long-period patterns. Special difficulty was encountered with the 6-kHz band of RFNs, possibly due to the lack of fine-structure phase locking at this frequency range. In addition, a similarity is noted between the organizational principles operating over particular durational ranges of stochastic patterns and the characteristics of traditional hierarchical units of speech having corresponding durations. PMID:11304013

Warren, R M; Bashford, J A; Cooley, J M; Brubaker, B S

2001-01-01

101

Efficient detection of motion patterns in spatio-temporal data sets  

Microsoft Academic Search

Moving point object data can be analyzed through the discovery of patterns. We consider the computational efficiency of detecting four such spatio-temporal patterns, namely flock, leadership, convergence, and encounter, as defined by Laube et al., 2004. These patterns are large enough subgroups of the moving point objects that exhibit similar movement in the sense of direction, heading for the same

Joachim Gudmundsson; Marc J. van Kreveld; Bettina Speckmann

2004-01-01

102

Analyzing temporal patterns of infant sleep and negative affective behavior: A comparison between different statistical models  

Microsoft Academic Search

ObjectiveVariability in infant sleep and negative affective behavior (NAB) is a developmental phenomenon that has long been of interest to researchers and clinicians. However, analyses and delineation of such temporal patterns were often limited to basic statistical approaches, which may prevent adequate identification of meaningful variation within these patterns. Modern statistical procedures such as additive models may detect specific patterns

Mirja H. Hemmi; Silvia Schneider; Silvana Müller; Andrea H. Meyer; Frank H. Wilhelm

2011-01-01

103

Discovery of Temporal Dependencies between Frequent Patterns in Multivariate Time Series  

Microsoft Academic Search

We consider the problem of mining multivariate time series data for discovering (i) frequently occurring substring patterns in a dimension, (ii) temporal associations among these substring patterns within or across different dimensions, and (iii) large intervals that sustain a particular mode of operation. These represent patterns at three different levels of abstraction for a dataset having very fine granularity. Discovery

Giridhar Tatavarty; Raj Bhatnagar; Barrington Young

2007-01-01

104

Spatio-temporal patterns of Campylobacter colonization in Danish broilers.  

PubMed

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

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

2012-07-20

105

ASSESSING TEMPORAL STABILITY AND SPATIAL VARIABILITY OF SOIL WATER PATTERNS WITH IMPLICATIONS FOR PRECISION WATER MANAGEMENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

The temporal stability of soil water content patterns may have profound implications for precision agriculture in general and water management in particular. However, it needs to be demonstrated that the scale of spatio-temporal variability is appropriate for precision farm management and that a yie...

106

Discovering evolutionary theme patterns from text: an exploration of temporal text mining  

Microsoft Academic Search

Temporal Text Mining (TTM) is concerned with discovering temporal patterns in text information collected over time. Since most text information bears some time stamps, TTM has many applications in multiple domains, such as summarizing events in news articles and revealing research trends in scientific literature. In this paper, we study a particular TTM task -- discovering and summarizing the evolutionary

Qiaozhu Mei; ChengXiang Zhai

2005-01-01

107

Temporal symmetry of individual filaments in different spatial symmetry filaments pattern in a dielectric barrier discharge  

SciTech Connect

The temporal behavior of individual filament in different spatial symmetry filaments patterns in dielectric barrier discharge is investigated by using an optical method. A series of return maps of the discharge moments of individual filaments is given. It is found that the temporal symmetry of individual filament changes with the change of the spatial symmetry of filaments pattern as the applied voltage increases. The role of wall charges for this phenomenon is analyzed.

Dong, L. F.; Xiao, H.; Fan, W. L.; Yin, Z. Q.; Zhao, H. T. [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

2010-10-15

108

Temporal Patterns in Long-Term Survival After Resuscitation From Out-of-Hospital Cardiac Arrest  

Microsoft Academic Search

Background—During the past quarter century, advances in treatment of cardiovascular disease have occurred that might potentially benefit survivors of sudden cardiac arrest (SCA). Little is known, however, about the temporal patterns in long-term survival among persons resuscitated from SCA. We hypothesized that long-term survival would improve over time and that this temporal pattern would be most evident for cardiac causes

Thomas D. Rea; Matthew Crouthamel; Mickey S. Eisenberg; Linda J. Becker; Ann R. Lima

109

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

Microsoft Academic Search

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

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

2010-01-01

110

Temporal demodulation of fringe patterns with sensitivity change  

Microsoft Academic Search

There are many phase measuring experimental setups in which the rate of temporal phase variation cannot be easily determined. In the case of phase stepping techniques, asynchronous phase measuring techniques were developed to solve this problem. However, there are situations for which the standard asynchronous techniques are not appropriated, like experiments with a sensitivity variation in the phase. In this

Juan A. Quiroga; José A. Gómez-Pedrero; M. José Terrón-López; Manuel Servin

2005-01-01

111

Discovering Temporal Patterns from Images using Extended PLSA  

Microsoft Academic Search

This paper considers the problem of modelling the topics in a sequence of images with known time stamp. Detecting and tracking of temporal data is an important task in multiple applications, such as finding hot research point from scientific literature, news article series analysis, email surveillance, search query log mining, etc. In contrast to existing works mainly focusing on text

Xiaofeng Liao; Yongji Wang; Liping Ding

2010-01-01

112

Objective Phonological and Subjective Perceptual Characteristics of Syllables Modulate Spatiotemporal Patterns of Superior Temporal Gyrus Activity  

PubMed Central

Natural consonant vowel syllables are reliably classified by most listeners as voiced or voiceless. However, our previous research (Liederman et al., 2005) suggests that among synthetic stimuli varying systematically in voice onset time (VOT), syllables that are classified reliably as voiceless are nonetheless perceived differently within and between listeners. This perceptual ambiguity was measured by variation in the accuracy of matching two identical stimuli presented in rapid succession. In the current experiment, we used magnetoencephalography (MEG) to examine the differential contribution of objective (i.e., VOT) and subjective (i.e., perceptual ambiguity) acoustic features on speech processing. Distributed source models estimated cortical activation within two regions of interest in the superior temporal gyrus (STG) and one in the inferior frontal gyrus. These regions were differentially modulated by VOT and perceptual ambiguity. Ambiguity strongly influenced lateralization of activation; however, the influence on lateralization was different in the anterior and middle/posterior portions of the STG. The influence of ambiguity on the relative amplitude of activity in the right and left anterior STG activity depended on VOT, whereas that of middle/posterior portions of the STG did not. These data support the idea that early cortical responses are bilaterally distributed whereas late processes are lateralized to the dominant hemisphere and support a “how/what” dual-stream auditory model. This study helps to clarify the role of the anterior STG, especially in the right hemisphere, in syllable perception. Moreover, our results demonstrate that both objective phonological and subjective perceptual characteristics of syllables independently modulate spatiotemporal patterns of cortical activation.

Frye, Richard E.; Fisher, Janet McGraw; Witzel, Thomas; Ahlfors, Seppo P.; Swank, Paul; Liederman, Jacqueline; Halgren, Eric

2008-01-01

113

Learning syntactically significant temporal patterns of chords: A masking field embedded in an ART 3 architecture  

Microsoft Academic Search

In the traditional harmonic s),nta.x of classical music, temporal patterns of chords vao, in length, they often nest one within another, and they may lack overt markers indicating pattern boundaries. Tire selJ:organized learning of such patterns can be accomplished by a maskingfwld embedded in an ART 3 architecture. A simulation of learning the chord patterns in the music of Handel

Robert O. Gjerdingen

1992-01-01

114

Temporal changes in colony cuticular hydrocarbon patterns of Solenopsis invicta  

Microsoft Academic Search

Heritable cuticular hydrocarbon patterns ofSolenopsis invicta workers are consistent within colonies for a given sampling time but vary sufficiently from colony to colony to distinguish the colonies from each other. In addition, cuticular hydrocarbon patterns change within colonies over time. Nestmate recognition cues found on the individual's cuticle, can be from heritable or environmental sources, and are a subset of

Robert K. vander Meer; David Saliwanchik; Barry Lavine

1989-01-01

115

Hemispatial PCA dissociates temporal from parietal ERP generator patterns  

PubMed Central

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

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

2008-01-01

116

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

117

A descriptive analysis of temporal and spatial patterns of variability in Puget Sound oceanographic properties  

Microsoft Academic Search

Temporal and spatial patterns of variability in Puget Sound's oceanographic properties are determined using continuous vertical profile data from two long-term monitoring programs; monthly observations at 16 stations from 1993 to 2002, and biannual observations at 40 stations from 1998 to 2003. Climatological monthly means of temperature, salinity, and density reveal strong seasonal patterns. Water temperatures are generally warmest (coolest)

Stephanie K. Moore; Nathan J. Mantua; Jan A. Newton; Mitsuhiro Kawase; Mark J. Warner; Jonathan P. Kellogg

2008-01-01

118

Temporal Patterns of Mental Model Convergence: Implications for Distributed Teams Interacting in Electronic Collaboration Spaces  

Microsoft Academic Search

Objective: Our objective is to capture temporal patterns in mental model convergence processes and differences in these patterns between distributed teams using an electronic collaboration space and face-to-face teams with no interface. Background: Distributed teams, as sociotechnical systems, collaborate via technology to work on their task. The way in which they process information to inform their mental models may be

Sara McComb; Deanna M. Kennedy; Rebecca Perryman; Norman Warner; Michael Letsky

2010-01-01

119

Aligning temporal data by sentinel events: discovering patterns in electronic health records  

Microsoft Academic Search

Electronic Health Records (EHRs) and other temporal databases contain hidden patterns that reveal important cause-and-effect phenomena. Finding these patterns is a challenge when using traditional query languages and tabular displays. We present an interactive visual tool that complements query formulation by providing operations to align, rank and filter the results, and to visualize estimates of the intervals of validity of

Taowei David Wang; Catherine Plaisant; Alexander J. Quinn; Roman Stanchak; Shawn Murphy; Ben Shneiderman

2008-01-01

120

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

121

Patterns of altered functional connectivity in mesial temporal lobe epilepsy  

PubMed Central

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

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

2013-01-01

122

Temporal difference method for processing dynamic speckle patterns  

NASA Astrophysics Data System (ADS)

A temporal difference method for processing dynamic speckle images is proposed. In the method two speckle images of an object, separated by a time interval, are subtracted one from the other to detect whether the speckle structure has changed or not. The rationale of the method is discussed. A variant of the method that allows measuring the area of an activity zone surrounded by a static region is tested in digital simulations. As a demonstrative experiment, that variant is employed to characterize the drying of a damp patch in filter paper.

Martí-López, L.; Cabrera, H.; Martínez-Celorio, R. A.; González-Peña, R.

2010-12-01

123

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

Microsoft Academic Search

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.

Clémentine Vignal; Darcy Kelley

2007-01-01

124

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.

Poeppel, David

2010-01-01

125

Automatic music video generation based on temporal pattern analysis  

Microsoft Academic Search

Music video (MV) is a short film meant to present a visual representation of a popular music song. In this paper, we present a system that automatically generates MV-like videos from personal home videos based on observations that generally there are obvious repetitive visual and aural patterns in MVs. Based on a set of video and music analysis algorithms, the

Xian-Sheng HUA; Lie LU; Hong-Jiang ZHANG

2004-01-01

126

SPATIAL AND TEMPORAL PATTERNS OF ACID PRECIPITATION AND THEIR INTERPRETATION  

EPA Science Inventory

Using data compiled from seven nationwide precipitation chemistry networks in the U.S. and Canada, the spatial distribution of hydrogen, sulfate, and nitrate ions in North America is discussed. Geographic patterns of concentration and deposition are characterized using isopleth m...

127

Temporal pattern of pulse wave velocity during brachial hyperemia reactivity  

NASA Astrophysics Data System (ADS)

Endothelial function can be assessed non-invasively with ultrasound, analyzing the change of brachial diameter in response to transient forearm ischemia. We propose a new technique based in the same principle, but analyzing a continuous recording of carotid-radial pulse wave velocity (PWV) instead of diameter. PWV was measured on 10 healthy subjects of 22±2 years before and after 5 minutes forearm occlusion. After 59 ± 31 seconds of cuff release PWV decreased 21 ± 9% compared to baseline, reestablishing the same after 533 ± 65 seconds. There were no significant changes observed in blood pressure. When repeating the study one hour later in 5 subjects, we obtained a coefficient of repeatability of 4.8%. In conclusion, through analysis of beat to beat carotid-radial PWV it was possible to characterize the temporal profiles and analyze the acute changes in response to a reactive hyperemia. The results show that the technique has a high sensitivity and repeatability.

Graf, S.; Valero, M. J.; Craiem, D.; Torrado, J.; Farro, I.; Zócalo, Y.; Valls, G.; Bía, D.; Armentano, R. L.

2011-09-01

128

Regulation and Temporal Expression Patterns of Vibrio cholerae Virulence Genes during Infection  

Microsoft Academic Search

The temporal expression patterns of the critical Vibrio cholerae virulence genes, tcpA and ctxA, were determined during infection using a recombinase reporter. TcpA was induced biphasically in two temporally and spatially separable events in the small intestine, whereas ctxA was induced monophasically only after, and remarkably, dependent upon, tcpA expression; however, this dependence was not observed during in vitro growth.

Sang Ho Lee; David L Hava; Matthew K Waldor; Andrew Camilli

1999-01-01

129

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

130

Spatial and temporal patterns of global onshore wind speed distribution  

NASA Astrophysics Data System (ADS)

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

Zhou, Yuyu; Smith, Steven J.

2013-09-01

131

Predicting Gene Ontology Biological Process From Temporal Gene Expression Patterns  

PubMed Central

The aim of the present study was to generate hypotheses on the involvement of uncharacterized genes in biological processes. To this end, supervised learning was used to analyze microarray-derived time-series gene expression data. Our method was objectively evaluated on known genes using cross-validation and provided high-precision Gene Ontology biological process classifications for 211 of the 213 uncharacterized genes in the data set used. In addition, new roles in biological process were hypothesized for known genes. Our method uses biological knowledge expressed by Gene Ontology and generates a rule model associating this knowledge with minimal characteristic features of temporal gene expression profiles. This model allows learning and classification of multiple biological process roles for each gene and can predict participation of genes in a biological process even though the genes of this class exhibit a wide variety of gene expression profiles including inverse coregulation. A considerable number of the hypothesized new roles for known genes were confirmed by literature search. In addition, many biological process roles hypothesized for uncharacterized genes were found to agree with assumptions based on homology information. To our knowledge, a gene classifier of similar scope and functionality has not been reported earlier. [Supplemental material is available online at www.genome.org. All annotations, reclassifications of known genes, and classifications of uncharacterized genes are available online at http://www.lcb.uu.se/?hvidsten/fibroblast.

Laegreid, Astrid; Hvidsten, Torgeir R.; Midelfart, Herman; Komorowski, Jan; Sandvik, Arne K.

2003-01-01

132

Temporal and behavioral patterning of parturition in rabbits and rats.  

PubMed

Although the rabbit (Oryctolagus cuniculus) continues to play an important role in the study of parturitional processes, a detailed behavioral description of birth in this species, necessary for accurately assessing the effects of experimental manipulation, is lacking. It is the aim of this report to provide such a description and to compare it with corresponding behavior in the better-studied rat. Ten pregnant chinchilla-breed rabbits and 10 pregnant Wistar rats were placed in glass-bottomed observation cages 2 days before term, and their behavior recorded on closed-circuit video, viewing the animals from below. All aspects of parturition were accomplished much faster in rabbits than rats; latency to birth of first pup, rate of delivery, duration of vaginal retention, time spent by mothers eating placentas, and in licking and nursing pups. In contrast to rat pups, rabbits were usually born separated from the placenta and already free from membranes. They were much more active, and well able to cast off any remaining membranes, suckle, and survive, whether directly attended to by the mother or not. We conclude that the tight temporal organization of events in the rabbit provides an unusually sensitive assay for investigating mechanisms underlying mammalian parturition. PMID:10386903

Hudson, R; Cruz, Y; Lucio, A; Ninomiya, J; Martínez-Gómez, M

1999-06-01

133

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

PubMed

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

2012-04-06

134

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.

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

2012-01-01

135

Empirical analysis on temporal statistics of human correspondence patterns  

NASA Astrophysics Data System (ADS)

Recently, extensive empirical evidence shows that the timing of human behaviors obeys non-Possion statistics with heavy-tailed interevent time distribution. In this paper, we empirically study the correspondence pattern of a great Chinese scientist, named Hsue-Shen Tsien. Both the interevent time distribution and response time distributions deviate from the Poisson statistics, showing an approximate power-law decaying. The two power-law exponents are more or less the same (about 2.1), which strongly support the hypothesis in [A. Vázquez, J.G. Oliveira, Z. Dezsö, K.-I. Goh, I. Kondor, A.-L. Barabási, Phys. Rev. E 73 (2006) 036127] that the response time distribution of the tasks could in fact drive the interevent time distribution, and both the two distributions should decay with the same exponent. Our result is against the claim in [A. Vázquez, J.G. Oliveira, Z. Dezsö, K.-I. Goh, I. Kondor, A.-L. Barabási, Phys. Rev. E 73 (2006) 036127], which suggests the human correspondence pattern belongs to a universality class with exponent 1.5.

Li, Nan-Nan; Zhang, Ning; Zhou, Tao

2008-11-01

136

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

137

The effects of morphine on fixed-interval patterning and temporal discrimination.  

PubMed Central

Changes produced by drugs in response patterns under fixed-interval schedules of reinforcement have been interpreted to result from changes in temporal discrimination. To examine this possibility, this experiment determined the effects of morphine on the response patterning of 4 pigeons during a fixed-interval 1-min schedule of food delivery with interpolated temporal discrimination trials. Twenty of the 50 total intervals were interrupted by choice trials. Pecks to one key color produced food if the interval was interrupted after a short time (after 2 or 4.64 s). Pecks to another key color produced food if the interval was interrupted after a long time (after 24.99 or 58 s). Morphine (1.0 to 10.0 mg/kg) decreased the index of curvature (a measure of response patterning) during fixed intervals and accuracy during temporal discrimination trials. Accuracy was equally disrupted following short and long sample durations. Although morphine disrupted temporal discrimination in the context of a fixed-interval schedule, these effects are inconsistent with interpretations of the disruption of response patterning as a selective overestimation of elapsed time. The effects of morphine may be related to the effects of more conventional external stimuli on response patterning.

Odum, A L; Schaal, D W

2000-01-01

138

Spatial patterns and temporal trends of precipitation in Iran  

NASA Astrophysics Data System (ADS)

Spatial patterns of monthly, seasonal and annual precipitation over Iran and the corresponding long-term trends for the period 1951-2009 are investigated using the Global Precipitation Climatology Centre gridded dataset. Results suggest that the spatial patterns of annual, winter and spring precipitation and the associated coefficients of variation reflect the role of orography and latitudinal extent between central-southern arid and semi-arid regions and northern and western mountainous areas. It is also shown that precipitation occurrence is almost regularly distributed within the year in northern areas while it is more concentrated in a few months in southern Iran. The spatial distribution of Mann-Kendal trend test (Z statistics) for annual precipitation showed downward trend in north-western and south-eastern Iran, whereas western, central and north-eastern exhibited upward trend, though not statistically significant in most regions. Results for winter and autumn revealed upward trend in most parts of the country, with the exception of north-western and south-eastern where a downward trend is observed; in spring and summer, a downward trend seems to prevail in most of Iran. However, for all seasons the areas where the detected trend is statistically significant are limited to a few spot regions. The overall results suggest that the precipitation is decreasing in spring and summer and increasing in autumn and winter in most of Iran, i.e. less precipitation during the warm season with a consequent intensification of seasonality and dryness of the country. However, since the detected trends are often not statistically significant, any stringent conclusion cannot be done on the future tendencies.

Raziei, Tayeb; Daryabari, Jamal; Bordi, Isabella; Pereira, Luis S.

2013-05-01

139

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.

140

Distinct roles for onset and sustained activity in the neuronal code for temporal periodicity and acoustic envelope shape  

PubMed Central

Auditory neurons are selective for temporal sound information that is important for rhythm, pitch, and timbre perception. Traditional models assume that periodicity information is represented either by the discharge rate of tuned modulation filters or synchrony in the discharge pattern. Compelling evidence for an invariant rate or synchrony code, however, is lacking and neither of these models account for how the sound envelope shape is encoded. We examined the neuronal representation for envelope shape and periodicity in the cat central nucleus of the inferior colliculus (CNIC) with modulated broadband noise that lack spectral cues and produce a periodicity pitch percept solely based on timing information. The modulation transfer functions of CNIC neurons differed dramatically across stimulus conditions with identical periodicity but different envelope shapes implying that shape contributed significantly to the neuronal response. We therefore devised a shuffled correlation procedure to quantify how periodicity and envelope shape contribute to the temporal discharge pattern. Sustained responses faithfully encode envelope shape at low modulation rates but deteriorate and fail to account for timing and envelope information at high rates. Surprisingly, onset responses accurately entrained to the stimulus and provided a means of encoding repetition information at high rates. Finally, we demonstrate that envelope shape information is accurately reflected in the population discharge pattern such that shape is readily discriminated for repetition frequencies up to ~100 Hz. These results argue against conventional rate or synchrony based codes and provides two complementary temporal mechanisms by which CNIC neurons can encode envelope shape and repetition information in natural sounds.

Zheng, Yi; Escabi, Monty A.

2009-01-01

141

Temporal variability and stability in infant-directed sung speech: evidence for language-specific patterns.  

PubMed

In this paper, sung speech is used as a methodological tool to explore temporal variability in the timing of word-internal consonants and vowels. It is hypothesized that temporal variability/stability becomes clearer under the varying rhythmical conditions induced by song.This is explored crosslinguistically in German - a language that exhibits a potential vocalic quantity distinction - and the non-quantity languages French and Russian. Songs by non-professional singers, i.e. parents that sang to their infants aged 2 to 13 months in a non-laboratory setting, were recorded and analyzed.Vowel and consonant durations at syllable contacts of trochaic word types with CVCV or CV:CV structure were measured under varying rhythmical conditions. Evidence is provided that in German non-professional singing, the two syllable structures can be differentiated by two distinct temporal variability patterns: vocalic variability (and consonantal stability) was found to be dominant in CV:CV structures whereas consonantal variability (and vocalic stability) was characteristic for CVCV structures. In French and Russian, however, only vocalic variability seemed to apply.Additionally, findings suggest that the different temporal patterns found in German were also supported by the stability pattern at the tonal level. These results point to subtle (supra) segmental timing mechanisms in sung speech that affect temporal targets according to the specific prosodic nature of the language in question. PMID:21848078

Falk, Simone

2011-06-01

142

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

143

Spatial and temporal habitat use patterns for salt marsh nekton: implications for ecological functions  

Microsoft Academic Search

We synthesized information on temporal and spatial patterns of salt marsh habitat use by nekton in order to infer the importance\\u000a of five main types of marsh function: reproduction, foraging, refuge from predation, refuge from stressful environmental conditions\\u000a and environmental enhancement of physiology. We then extended the concept that intertidal gradients regulate habitat use patterns\\u000a of nekton to a more

Rodney A. Rountree; Kenneth W. Able

2007-01-01

144

Spatio-temporal expression patterns of anterior Hox genes during Nile tilapia (Oreochromis niloticus) embryonic development.  

PubMed

Hox genes encode transcription factors that function to pattern regional tissue identities along the anterior-posterior axis during animal embryonic development. Divergent nested Hox gene expression patterns within the posterior pharyngeal arches may play an important role in patterning morphological variation in the pharyngeal jaw apparatus (PJA) between evolutionarily divergent teleost fishes. Recent gene expression studies have shown the expression patterns from all Hox paralog group (PG) 2-6 genes in the posterior pharyngeal arches (PAs) for the Japanese medaka (Oryzias latipes) and from most genes of these PGs for the Nile tilapia (Oreochromis niloticus). While several orthologous Hox genes exhibit divergent spatial and temporal expression patterns between these two teleost species in the posterior PAs, several tilapia Hox gene expression patterns from PG3-6 must be documented for a full comparative study. Here we present the spatio-temporal expression patterns of hoxb3b, c3a, b4a, a5a, b5a, b5b, b6a and b6b in the neural tube and posterior PAs of the Nile tilapia. We show that several of these tilapia Hox genes exhibit divergent expression patterns in the posterior PAs from their medaka orthologs. We also compare these gene expression patterns to orthologs in other gnathostome vertebrates, including the dogfish shark. PMID:23376031

Lyon, R Stewart; Davis, Adam; Scemama, Jean-Luc

2013-02-01

145

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

Microsoft Academic Search

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

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

2010-01-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

147

The temporal pattern of economic evaluations and vote choice in Senate elections  

Microsoft Academic Search

Economics has long been thought to influence vote choice. Unfortunately, the temporal pattern of economic evaluations is little studied. Using the Senate elections of 1956 through 1988, this research presents an assessment of the role of retrospective and prospective evaluations on vote choice. The findings of this research support the argument that people look to the future when making the

Brad Lockerbie

1991-01-01

148

Spatial and temporal patterns of arsenic concentration in the High Plains Aquifer of Texas, USA  

Microsoft Academic Search

Spatial and temporal patterns of dissolved arsenic in groundwater were documented from samples collected at 987 water wells in the High Plains (Ogallala) Aquifer of Texas, USA. Sampled wells had a median depth of 73 m. Historic pesticide and defoliant applications to cotton fields are potential sources of arsenic in the study area. From a survey of samples collected between

Paul F. Hudak

2006-01-01

149

Stomach temperature telemetry reveals temporal patterns of foraging success in a free-ranging marine mammal  

Microsoft Academic Search

Summary 1. We studied feeding frequency in free-ranging grey seals using stomach temperature telemetry to test if previously reported sex differences in the diving, movement and diet were reflected in the temporal pattern of foraging success. 2. Data were retrieved from 21 of 32 grey seals from 1999 to 2001, totalling 343 days and 555 feeding events, with individual record

DEBORAH AUSTIN; W. D. BOWEN; J. I. MCMILLAN; D. J. BONESS

2006-01-01

150

Anxiety intensity and direction: Preperformance temporal patterns and expectations in athletes  

Microsoft Academic Search

The purpose of this study was to identify temporal patterns of anxiety and self-confidence levels, with respect to both the intensity and direction (i.e., perceived favonbility) of these symptoms, and precompetitive performance expectations at three times prior to competition. Participants were 91 high school and college athletes competing in soccer, swimming. and tnck and field. Results indicated that anxiety intensity

Matthew S. Wiggins

1998-01-01

151

Parrot behavior at a Rio Manu (Peru) clay lick: temporal patterns, associations, and antipredator responses  

Microsoft Academic Search

Although eating clay at licks (a form of geophagy) has been described, there are few behavioral data on temporal patterns, social interactions, species associations, or reactions to potential predators. We examined the behavior of nine species of macaws, parrots, and parakeets at the Machiguenga Ccolpa, a clay lick on the Rio Manu, Peru in the dry season. Three distinct mixed-species

Joanna Burger; Michael Gochfeld

2003-01-01

152

Using structure patterns of temporal and spectral feature in audio similarity measure  

Microsoft Academic Search

Although statistical characteristics of audio features are widely used for similarity measure in most of current audio analysis systems and have been proved to be effective, they only utilized the averaged feature variations over time, and thus lead to inaccuracy in some cases. In this paper, structure pattern, which describes the representative structure characteristics of both temporal and spectral features,

Rui Cai; Lie Lu; Hong-Jiang Zhang

2003-01-01

153

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

Microsoft Academic Search

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

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

2007-01-01

154

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

Microsoft Academic Search

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

Olivier Vincent; Ivan Roditchev; Philippe Marmottant; Tom Waigh

2011-01-01

155

The basic pattern of activation in motor and sensory temporal tasks: positron emission tomography data  

Microsoft Academic Search

Positron emission tomography (PET) data were obtained from subjects performing a synchronization task (target duration 2700 ms). A conjunction analysis was run to identify areas prominently activated both in this task and in a temporal generalization task (target duration 700 ms) used previously. The common pattern of activation included the right prefrontal, inferior parietal and anterior cingulate cortex, the left

Helga Lejeune; Pierre Maquet; Michel Bonnet; Laurence Casini; Andre Ferrara; Francoise Macar; Viviane Pouthas; Martine Timsit-Berthier; Franck Vidal

1997-01-01

156

Spatial and temporal patterns of fuelwood collection in Wolong Nature Reserve: Implications for panda conservation  

Microsoft Academic Search

Approximately 3 billion people, half of the World's population, are still using fuelwood in their daily lives. Fuelwood collection has been recognized as an important factor in habitat fragmentation and degradation and biodiversity loss, especially in developing countries. Understanding spatial and temporal patterns of fuelwood collection is fundamental to understanding human–environment interactions and designing effective conservation policies. Using Wolong Nature

Guangming He; Xiaodong Chen; Scott Beaer; Manuel Colunga; Angela Mertig; Li An; Shiqiang Zhou; Marc Linderman; Zhiyun Ouyang; Stuart Gage; ShuXin Li; Jianguo Liu

2009-01-01

157

Skeletal mineralogy of bryozoans: Taxonomic and temporal patterns  

NASA Astrophysics Data System (ADS)

Skeletal carbonate mineralogy of 1183 specimens of marine bryozoans from the literature was examined for phylogenetic patterns in order to elucidate the effects of bryozoan mineralogy on geochemical and paleoenvironmental analysis. Colonies are composed of calcite (66% of specimens), aragonite (17% of specimens) or various mixtures of the two (17% specimens) (phylum mean = 72.9 wt.% calcite, n = 1051). When calcite is present, it ranges from 0.0 to 13.7 wt.% MgCO 3 (mean = 5.0 wt.% MgCO 3, n = 873). Most (61%) calcitic specimens are formed of intermediate-Mg calcite (4 to 8 wt.% MgCO 3), others (28%) of low-Mg calcite (0 to 4 wt.% MgCO 3), and few of high-Mg calcite (> 8 wt.% MgCO 3). The phylum occupies at least 63% of the theoretical mineralogical "space" available to biomineralisation. Most of this variation occurs in the class Gymnolaemata, order Cheilostomata, suborder Neocheilostomata. Fossil and Recent stenolaemate taxa are generally low- to intermediate-Mg calcite (mean = 99.7 wt.% calcite, 2.6 wt.% MgCO 3, 17% of available biomineral space). Variability among families is related in a general way to first appearance datum: families younger than 100 Ma display greater mineralogical complexity than older ones. The cheilostome infraorder Flustrina includes unusual free-living aragonitic families, dual-calcite skeletons (mainly low-Mg calcite, but with secondary high-Mg calcite), and some genera with considerable mineralogical variability. Families (e.g., Membraniporidae and Phidoloporidae) and species (e.g., Schizoporella unicornis) with the highest degree of variability have potential for environmental correlations with mineralogy, paleoenvironmental interpretation, and possibly molecular investigation for potential cryptic species. Stenolaemate families, genera and species with low variability, on the other hand, are well-suited for geochemical work such as stable isotope analysis. Variability in the skeletal mineralogy of bryozoans suggests that they may be useful in geochemical, phylogenetic, and paleoenvironmental studies, with careful choice of study material.

Smith, Abigail M.; Key, Marcus M., Jr.; Gordon, Dennis P.

2006-10-01

158

Geochemical and temporal patterns of felsic volcanism in Ethiopia  

SciTech Connect

At least three major geochemical groups characterize late Cenozoic felsic volcanism exposed in the central Ethiopian Rift graben or along its uplifted margins. Each group is distinguished by age and/or position with distinctive compositional traits that are probably tectonically controlled. They include: (1) large-volume Pliocene tholeiitic to calcalkaline rhyolitic ignimbrites that form >500m thick exposures along the rift margins. These have moderate FeO/sub T/ (1.5-3.0%), low CaO (<0.5%) and moderately steep REE slopes (Ce/Yb = 21-24) with large negative Eu anomalies (Eu/Eu* = 0.2-0.4). K/Ar ages range from 4.5 to 3.0 Ma. These ignimbrites must have been associated with major caldera-forming events, but no calderas of this age or chemistry have yet been found; (2) Plio-Pleistocene trachytic volcanoes occur on the Ethiopian Highland, parallel to the rift axis. These have low SiO/sub 2/ (60-70%), high FeO/sub T/ (4-8%) and steep REE patterns (Ce/Yb = 25-37) with very small negative Eu anomalies (0.8-0.9). The volcanoes of Chilalo, Kaka, Hunkulu and the Bada Range are of this group. K/Ar ages range from 3.5 to 1.0 Ma; (3) Pleistocene peralkaline rhyolitic volcanoes of the Ethiopian Rift graben have high FeO/sub T/ (5-8%), high Na/sub 2/O (6-8%) and shallow REE profiles (Ce/Yb = 14-21) with small Eu anomalies (0.5 to 0.6). K/Ar ages range from 0.5 to <0.05 Ma. The volcanoes of Aluto and Dofen are of this group. Eruption of Group 1 signaled the modern rapid development of the present rift; Group 2 overlapped in time and mainly was confined to the Plateau margins; and Group 3 represents the present mature stage of rift floor volcanism.

Walter, R.C.; Westgate, J.A.; Giday, W.G.; Aronson, J.L.; Hart, W.K.

1985-01-01

159

Spatio-temporal patterns and covariance structures of soil water status in two Northeast-German field sites  

Microsoft Academic Search

Spatio-temporal patterns of soil moisture status highly affect the heterogeneity of soil water and solute transport and leaching of chemicals to the groundwater. In order to quantify and describe spatial variability of ecologically highly relevant spatial and temporal processes linked to soil moisture at the land surface, the spatio-temporal covariance structure and the reasons for its change in time need

O. Wendroth; W. Pohl; S. Koszinski; H. Rogasik; C. J. Ritsema; D. R. Nielsen

1999-01-01

160

Temporal changes in the spatial pattern of disease rates incorporating known risk factors.  

PubMed

Examining the geographical pattern of temporal changes in infant mortality rates illustrates the methodological problems of documenting and understanding temporal changes in any spatial pattern of disease. Early research on geographical differences in infant mortality rates showed strong ecological correlations with socio-economic factors such as poverty rates. More recent research established relationships between individual-level socio-economic values and probabilities of death. With geographic information available at the level of individuals, it is possible to estimate the probabilities of death on a person-by-person basis from knowledge of the relationships between individual factors and socio-economic measures. These estimated probabilities provide an expected geographic pattern of deaths. The difference between the observed spatial pattern and the expected pattern is the remaining spatial variation adjusted for this knowledge. For the study area, individual factors and some socio-economic measures were available for each year of the study period. Using data from the Iowa Birth Defects Registry and the Iowa Department of Public Health (USA), I tested the stability and continuity of these cross-sectional relationships and investigated whether any temporal lags in these variables relate to the unexplained spatial variations in infant mortality rates that remain. I accounted for the 'Change of Support Problem' [Gotway C. A. & Young L. J. (2002). Combining incompatible spatial data. Journal of the American Statistical Association, 97458, 632-648] inherent in frame-based geographical analysis. The analysis involved a generalized linear model (GLM) to estimate individual risks and a Monte Carlo simulation model to generate the non-linear probability density functions for disease rates whose densities are theoretically intractable. Results show the temporal changes in the observed spatial pattern and the expected spatial pattern differ by geographic location. In conclusion such differences are the result of a combination of unexplained place-based risk and unmeasured individual risks. PMID:17509742

Banerjee, Aniruddha

2007-05-16

161

Global similarity and pattern separation in the human medial temporal lobe predict subsequent memory.  

PubMed

Intense debate surrounds the role of medial temporal lobe (MTL) structures in recognition memory. Using high-resolution fMRI and analyses of pattern similarity in humans, we examined the encoding computations subserved by MTL subregions. Specifically, we tested the theory that MTL cortex supports memory by encoding overlapping representations, whereas hippocampus supports memory by encoding pattern-separated representations. Consistent with this view, the relationship between encoding pattern similarity and subsequent memory dissociated MTL cortex and hippocampus: later memory was predicted by greater across-item pattern similarity in perirhinal cortex and in parahippocampal cortex, but greater pattern distinctiveness in hippocampus. Additionally, by comparing neural patterns elicited by individual stimuli regardless of subsequent memory, we found that perirhinal cortex and parahippocampal cortex exhibited differential content sensitivity for multiple stimulus categories, whereas hippocampus failed to demonstrate content sensitivity. These data provide novel evidence that complementary MTL encoding computations subserve declarative memory. PMID:23536062

LaRocque, Karen F; Smith, Mary E; Carr, Valerie A; Witthoft, Nathan; Grill-Spector, Kalanit; Wagner, Anthony D

2013-03-27

162

Global Similarity and Pattern Separation in the Human Medial Temporal Lobe Predict Subsequent Memory  

PubMed Central

Intense debate surrounds the role of medial temporal lobe (MTL) structures in recognition memory. Using high-resolution fMRI and analyses of pattern similarity in humans, we examined the encoding computations subserved by MTL subregions. Specifically, we tested the theory that MTL cortex supports memory by encoding overlapping representations, whereas hippocampus supports memory by encoding pattern-separated representations. Consistent with this view, the relationship between encoding pattern similarity and subsequent memory dissociated MTL cortex and hippocampus: later memory was predicted by greater across-item pattern similarity in perirhinal cortex and in parahippocampal cortex, but greater pattern distinctiveness in hippocampus. Additionally, by comparing neural patterns elicited by individual stimuli irrespective of subsequent memory, we found that perirhinal cortex and parahippocampal cortex exhibited differential content sensitivity for multiple stimulus categories, whereas hippocampus failed to demonstrate content sensitivity. These data provide novel evidence that complementary MTL encoding computations subserve declarative memory.

LaRocque, Karen F.; Smith, Mary E.; Carr, Valerie A.; Witthoft, Nathan; Grill-Spector, Kalanit; Wagner, Anthony D.

2013-01-01

163

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

NASA Astrophysics Data System (ADS)

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

Erdem, J.; Waite, G. P.

2011-12-01

164

Optimal rainfall temporal patterns for urban drainage design in the context of climate change.  

PubMed

The main objective of the present study is to propose a method for estimating an optimal temporal storm pattern for urban drainage design in southern Quebec (Canada) in the context of climate change. Following a systematic evaluation of the performance of eight popular design storm models for different typical urban basins, it was found that the Canadian Atmospheric Environment Service (AES) storm pattern and the Desbordes model (with a peak intensity duration of 30 min) were the most accurate for estimating runoff peak flows while the Watt model gave the best estimation of runoff volumes. Based on these analyses, an optimal storm pattern was derived for southern Quebec region. The proposed storm pattern was found to be the most suitable for urban drainage design in southern Quebec since it could provide accurate estimation of both runoff peak flow and volume. Finally, a spatial-temporal downscaling method, based on a combination of the spatial statistical downscaling SDSM technique and the temporal scaling General Extreme Value distribution, was used to assess the climate change impacts on the proposed optimal design storm pattern and the resulting runoff properties. PMID:20818061

Nguyen, V-T-V; Desramaut, N; Nguyen, T-D

2010-01-01

165

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

166

An application of Cyclic Signature (CS) clustering for spatial-temporal pattern analysis to support public safety work  

Microsoft Academic Search

In this paper, we propose a novel approach, Cyclic Signature (CS) clustering, to analyze spatial-temporal pattern. CS clustering is based on the calendar regularities of events to analyze spatial-temporal patterns. An experiment, based on a set of reported crime data for a district in Hong Kong, was performed to compare CS clustering against traditional clustering approaches. The results show that

Stephen Chi-fai Chan; Kelvin Leong

2010-01-01

167

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.

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

2013-01-01

168

Developmental regulation of spatio-temporal patterns of cortical circuit activation  

PubMed Central

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

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

2013-01-01

169

The timing and temporal patterns of eye blinking are dynamically modulated by attention.  

PubMed

A number of human behaviors and movements show self-similar temporal patterns in their occurrence over time. Human walking, finger tapping and heartbeat intervals have fluctuations that are statistically similar at multiple time scales. However, whether eye blinking, which is a unique human behavior that occurs spontaneously, embeds a similar temporal structure within other types of movements is largely unknown. In this study, we used attention-requiring tasks to assess how the temporal pattern of eye blinking is altered in both the second and sub-second time scales. Our results showed that eyeblink activity was more suppressed as the task difficulty level increased and was facilitated immediately after exposure to auditory stimuli, which were presented for 6 to 14s. Moreover, similar transient suppressive and facilitative patterns were observed in the response period, which lasted for less than one second. Furthermore, we found that spontaneous eye blinking intervals fluctuated according to an 1/f scaling property, which is widely observed in various human movements. These results suggest that the dynamics of eye blinking under specific cognitive tasks exhibit a similar temporal structure at multiple time scales. PMID:22877514

Oh, Jihoon; Jeong, So-Yeong; Jeong, Jaeseung

2012-08-09

170

Ipsilateral blinking seizures during left fronto-temporal ictal pattern on scalp EEG.  

PubMed

We report an infant with left eye blinking seizures accompanying a left (ipsilateral) fronto-temporal scalp EEG ictal pattern. The epileptogenic lesion was a left frontal encephalomalacia along the ventriculo-peritoneal shunt tract. The shunt was inserted for treatment of communicating hydrocephalus. This case illustrates the lateralizing value of the ictal blinking. Review of the literature suggests that seizures with unilateral blinking are likely to be produced by activation of ipsilateral trigeminal fibers innervating subdural intracranial structures and pial vessels in temporal and frontal lobes. Ipsilateral blinking could also be produced by activation of the ipsilateral cerebellar hemisphere. PMID:18077233

Pestana, Elia M; Gupta, Ajay

2007-12-01

171

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

172

A topological and temporal correlator network for spatiotemporal pattern learning, recognition, and recall.  

PubMed

In this paper, we describe the design of an artificial neural network for spatiotemporal pattern recognition and recall. This network has a five-layered architecture and operates in two modes: pattern learning and recognition mode, and pattern recall mode. In pattern learning and recognition mode, the network extracts a set of topologically and temporally correlated features from each spatiotemporal input pattern based on a variation of Kohonen's self-organizing maps. These features are then used to classify the input into categories based on the fuzzy ART network. In the pattern recall mode, the network can reconstruct any of the learned categories when the appropriate category node is excited or probed. The network performance was evaluated via computer simulations of time-varying, two-dimensional and three-dimensional data. The results show that the network is capable of both recognition and recall of spatiotemporal data in an on-line and self-organized fashion. The network can also classify repeated events in the spatiotemporal input and is robust to noise in the input such as distortions in the spatial and temporal content. PMID:18252532

Srinivasa, N; Ahuja, N

1999-01-01

173

Effects of varying temporal scale on spatial models of mortality patterns attributed to pediatric diarrhea.  

PubMed

Public health data is often highly aggregated in time and space. The consequences of temporal aggregation for modeling in support of policy decisions have largely been overlooked. We examine the effects of changing temporal scale on spatial regression models of pediatric diarrhea mortality patterns, mortality rates and mortality peak timing, in Mexico. We compare annual and decadal level univariate models that incorporate known risk factors. Based on normalized sums of squared differences we compare between annual and decadal coefficients for variables that were significant in decadal models. We observed that spurious relationships might be created through aggregating time scales; obscuring interannual variation and resulting in inflated model diagnostics. In fact, variable selection and coefficient values can vary with changing temporal aggregation. Some variables that were significant at the decadal level were not significant at the annual level. Implications of such aggregation should be part of risk communication to policy makers. PMID:22623950

Leyk, S; McCormick, B J J; Nuckols, J R

2011-06-01

174

Pattern of BOLD signal in auditory cortex relates acoustic response to perceptual streaming  

PubMed Central

Background Segregating auditory scenes into distinct objects or streams is one of our brain's greatest perceptual challenges. Streaming has classically been studied with bistable sound stimuli, perceived alternately as a single group or two separate groups. Throughout the last decade different methodologies have yielded inconsistent evidence about the role of auditory cortex in the maintenance of streams. In particular, studies using functional magnetic resonance imaging (fMRI) have been unable to show persistent activity within auditory cortex (AC) that distinguishes between perceptual states. Results We use bistable stimuli, an explicit perceptual categorization task, and a focused region of interest (ROI) analysis to demonstrate an effect of perceptual state within AC. We find that AC has more activity when listeners perceive the split percept rather than the grouped percept. In addition, within this ROI the pattern of acoustic response across voxels is significantly correlated with the pattern of perceptual modulation. In a whole-brain exploratory test, we corroborate previous work showing an effect of perceptual state in the intraparietal sulcus. Conclusions Our results show that the maintenance of auditory streams is reflected in AC activity, directly relating sound responses to perception, and that perceptual state is further represented in multiple, higher level cortical regions.

2011-01-01

175

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

PubMed

Capturing the functionality of active dendritic processing into abstract mathematical models will help us to understand the role of complex biophysical neurons in neuronal computation and to build future useful neuromorphic analog Very Large Scale Integrated (aVLSI) neuronal devices. Previous work based on an aVLSI multi-compartmental neuron model demonstrates that the compartmental response in the presence of either of two widely studied classes of active mechanisms, is a nonlinear sigmoidal function of the degree of either input temporal synchrony OR input clustering level. Using the same silicon model, this work expounds the interaction between both active mechanisms in a compartment receiving input patterns of varying temporal AND spatial clustering structure and demonstrates that this compartmental response can be captured by a combined sigmoid and radial-basis function over both input dimensions. This paper further shows that the response to input spatio-temporal patterns in a one-dimensional multi-compartmental dendrite, can be described by a radial-basis like function of the degree of temporal synchrony between the inter-compartmental inputs. PMID:23853330

Wang, Yingxue; Liu, Shih-Chii

2013-06-01

176

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

177

Temporal coherence among tropical coastal lagoons: a search for patterns and mechanisms.  

PubMed

Temporal coherence (i.e., the degree of synchronicity of a given variable among ecological units within a predefined space) has been shown for several limnological features among temperate lakes, allowing predictions about the structure and function of ecosystems. However, there is little evidence of temporal coherence among tropical aquatic systems, where the climatic variability among seasons is less pronounced. Here, we used data from long-term monitoring of physical, chemical and biological variables to test the degree of temporal coherence among 18 tropical coastal lagoons. The water temperature and chlorophyll-a concentration had the highest and lowest temporal coherence among the lagoons, respectively, whereas the salinity and water colour had intermediate temporal coherence. The regional climactic factors were the main factors responsible for the coherence patterns in the water temperature and water colour, whereas the landscape position and morphometric characteristics explained much of the variation of the salinity and water colour among the lagoons. These results indicate that both local (lagoon morphometry) and regional (precipitation, air temperature) factors regulate the physical and chemical conditions of coastal lagoons by adjusting the terrestrial and marine subsidies at a landscape-scale. On the other hand, the chlorophyll-a concentration appears to be primarily regulated by specific local conditions resulting in a weak temporal coherence among the ecosystems. We concluded that temporal coherence in tropical ecosystems is possible, at least for some environmental features, and should be evaluated for other tropical ecosystems. Our results also reinforce that aquatic ecosystems should be studied more broadly to accomplish a full understanding of their structure and function. PMID:21085785

Caliman, A; Carneiro, L S; Santangelo, J M; Guariento, R D; Pires, A P F; Suhett, A L; Quesado, L B; Scofield, V; Fonte, E S; Lopes, P M; Sanches, L F; Azevedo, F D; Marinho, C C; Bozelli, R L; Esteves, F A; Farjalla, V F

2010-10-01

178

Influence of velocity, temporal frequency and initial phase position of grating patterns on motion VEP.  

PubMed

The cortical potential visually evoked by motion of a periodic grating (motion VEP) is composed of a transient component which decays within 500 ms of stimulus-onset (motion-on VEP) and a sustained component. Amplitude and peak latency of wave N2 of the motion-on VEP are functions of grating velocity. Both remain constant at spatial frequencies between 0.6 and 4.3 c/deg and at temporal frequencies within the equivalent intervals. The transient component of the motion VEP is independent of the spatial phase position of the grating before motion onset. The sustained component can only be seen in the averaged motion VEP at constant phase position of the grating before motion onset. This potential consists of periodical fluctuations with a main frequency equal to the temporal frequency of the moving grating. As a result of psychophysical investigations some authors suggest pattern velocity is the relevant variable of velocity perception, others temporal frequency. The motion VEP is dependent on both velocity and temporal frequency, the transient component is a function of velocity, the sustained component of temporal frequency. PMID:3240305

Markwardt, F; Göpfert, E; Müller, R

1988-01-01

179

Temporal and Spatial Distribution Patterns of Larval Trichoptera in Madeiran Streams  

Microsoft Academic Search

Temporal and spatial distribution patterns of lotic larval trichopteran assemblages in relation to environmental variables\\u000a were investigated in Madeiran streams using multivariate analyses. TWINSPAN classification detected distinct faunal assemblages\\u000a related to spatial factors between non-polluted high altitude sites and lower lying enriched sites where tolerant taxa were\\u000a predominant but showed strong seasonal shifts in species composition and abundance. The 15

Samantha Jane Hughes

2006-01-01

180

The temporal pattern of mortality responses to ambient ozone in the APHEA project  

Microsoft Academic Search

Background:The temporal pattern of effects of summertime ozone (O3) in total, cardiovascular and respiratory mortality were investigated in 21 European cities participating in the APHEA-2 (Air Pollution and Health: a European Approach) project, which is fundamental in determining the importance of the effect in terms of life loss.Methods:Data from each city were analysed separately using distributed lag models with up

E Samoli; A Zanobetti; J Schwartz; R Atkinson; A LeTertre; C Schindler; L Pérez; E Cadum; J Pekkanen; A Paldy; G Touloumi; K Katsouyanni

2009-01-01

181

Temporal and spatial patterns of mass flowerings on the Malay Peninsula  

Microsoft Academic Search

We propose a hypothesis to explain the temporal and spatial patterns of mass flowerings in dipterocarp tree species on the Malay Peninsula. The literature on these mass flowerings reveals that during 1980-2002 at least 11 flowerings occurred at irregular intervals of 1-6 yr in a lowland rain forest. Five of them were typical mass flowerings—a high density of flowering trees

SHINYA NUMATA; MASATOSHI YASUDA; TOSHINORI OKUDA; NAOKI KACHI

2003-01-01

182

A sequence identification measurement model to investigate the implicit learning of metrical temporal patterns.  

PubMed

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

2013-09-25

183

Spatial and temporal patterns of trends and variability in diurnal temperature ranges of Turkey  

Microsoft Academic Search

Summary Spatial and temporal patterns of trends in the diurnal temperature ranges ( DTRs) of the 70 stations and the role of maximum and minimum temperatures on the year-to-year variability and the long-term trends of the DTRs in Turkey have been investigated for the period 1929–1999. The principal results of the study are as follows: (i) The daytime maximum temperatures

M. Türkes; U. M. Sümer

2004-01-01

184

Temporal Patterns of Caregiving for Preterm Infants Indicate Individualized Developmental Care  

Microsoft Academic Search

OBJECTIVE: Individualized attention for premature infants was assessed from temporal patterns of caregiving at three very different regional NICUs.STUDY DESIGN: Continuous time-lapse video recording of 95 premature infants under 1500 g was made over three 24-hour periods when they were 33 weeks' and 35 weeks' conceptional age.STATISTICAL ANALYSIS: Analysis of variance was used to compare caregiving measures within and across

Evelyn B Thoman

2003-01-01

185

Learning Automaton Based On-Line Discovery and Tracking of Spatio-temporal Event Patterns  

Microsoft Academic Search

\\u000a Discovering and tracking of spatio-temporal patterns in noisy sequences of events is a difficult task that has become increasingly\\u000a pertinent due to recent advances in ubiquitous computing, such as community-based social networking applications. The core\\u000a activities for applications of this class include the sharing and notification of events, and the importance and usefulness\\u000a of these functionalites increases as event-sharing expands

Anis Yazidi; Ole-Christoffer Granmo; Min Lin; Xifeng Wen; B. John Oommen; Martin Gerdes; Frank Reichert

2010-01-01

186

Enhancement in flaw detectability by means of lockin temporal speckle pattern interferometry and thermal waves  

NASA Astrophysics Data System (ADS)

A lockin method which takes into account the contribution of several modes from the Fourier spectrum generated by a heat load following a triangular waveform is used in temporal speckle pattern interferometry (TSPI) for the nondestructive detection of defects. By defining a parameter to quantify defect detectability, it is demonstrated that the use of this technique improves the detection of hidden flaws located in metal plates.

Dolinko, Andrés E.; Kaufmann, Guillermo H.

2007-06-01

187

Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns  

Microsoft Academic Search

This study examined the end-of-winter snow storage, its distribution and the spatial and temporal melt patterns of a large, low gradient wetland at Polar Bear Pass, Bathurst Island, Nunavut, Canada. The project utilized a combination of field observations and a physically-based snowmelt model. Topography and wind were the major controls on snow distribution in the region, and snow was routinely

Jane Assini; Kathy L. Young

2012-01-01

188

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.

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

2013-01-01

189

Mixed-Drove Spatio-Temporal Co-occurence Pattern Mining: A Summary of Results  

Microsoft Academic Search

Mixed-drove spatio-temporal co-occurrence patterns (MDCOPs) represent subsets of object-types that are located together in space and time. Discovering MDCOPs is an important problem with many applications such as identifying tactics in battlefields, games, and predator-prey interactions. However, mining MDCOPs is computationally very expensive because the interest measures are computationally complex, datasets are larger due to the archival history, and the

Mete Celik; Shashi Shekhar; James P. Rogers; James A. Shine; Jin Soung Yoo

2006-01-01

190

Span: spike pattern association neuron for learning spatio-temporal spike patterns.  

PubMed

Spiking Neural Networks (SNN) were shown to be suitable tools for the processing of spatio-temporal information. However, due to their inherent complexity, the formulation of efficient supervised learning algorithms for SNN is difficult and remains an important problem in the research area. This article presents SPAN - a spiking neuron that is able to learn associations of arbitrary spike trains in a supervised fashion allowing the processing of spatio-temporal information encoded in the precise timing of spikes. The idea of the proposed algorithm is to transform spike trains during the learning phase into analog signals so that common mathematical operations can be performed on them. Using this conversion, it is possible to apply the well-known Widrow-Hoff rule directly to the transformed spike trains in order to adjust the synaptic weights and to achieve a desired input/output spike behavior of the neuron. In the presented experimental analysis, the proposed learning algorithm is evaluated regarding its learning capabilities, its memory capacity, its robustness to noisy stimuli and its classification performance. Differences and similarities of SPAN regarding two related algorithms, ReSuMe and Chronotron, are discussed. PMID:22830962

Mohemmed, Ammar; Schliebs, Stefan; Matsuda, Satoshi; Kasabov, Nikola

2012-07-12

191

Spatial and temporal coherence of broadband acoustic transmissions in the Straits of Florida  

NASA Astrophysics Data System (ADS)

Month-long time series of broadband coherent measurements of channel pulse responses in the Florida Straits allow for estimation of signal coherence under a great variety of signal parameters and environmental conditions. Two 32-element arrays, one vertical and another horizontal (bottomed) along the path of propagation allow for comparison of spatial coherency and single phone temporal coherencies. The transmitted signals cover 5 octaves from 100 through 3200 Hz. Coherencies for single resolved SRBR arrivals are compared with those for unresolved multipath BRB focused arrivals. Many factors are at play including the complication of coherent reception from nearby shipping and multipath interference. However, the time series are long enough to sort out and explain most relations to the environmental variability. Vertical and horizontal coherence lengths are compared over a wide range of frequencies. Generally, SBRB paths are found to be far more stable and coherent than RBR paths especially at higher frequencies suggesting that sound-speed variability near turning RBR rays/modes is more destructive to coherency. The loss of signal coherency for RBR paths is accompanied by a significant loss of signal intensity-as much as 10 to 15 dB.

Deferrari, Harry A.; Williams, Neil; Nguyen, Hien

2003-04-01

192

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

PubMed

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

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

2013-09-05

193

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

PubMed Central

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

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

2013-01-01

194

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

195

Temporal patterns in ambient noise of biological origin from a shallow water temperate reef.  

PubMed

A systematic study of the ambient noise in the shallow coastal waters of north-eastern New Zealand shows large temporal variability in acoustic power levels between seasons, moon phase and the time of day. Ambient noise levels were highest during the new moon and the lowest during the full moon. Ambient noise levels were also significantly higher during summer and lower during winter. Bandpass filtering (700-2,000 Hz and 2-15 kHz), combined with snap counts and data from other studies show that the majority of the sound intensity increases could be attributed to two organisms: the sea urchin and the snapping shrimp. The increased intensity of biologically produced sound during dusk, new moon and summer could enhance the biological signature of a reef and transmit it further offshore. Ambient noise generated from the coast, especially reefs, has been implicated as playing a role in guiding pelagic post-larval fish and crustaceans to settlement habitats. Determining a causal link between temporal increases in ambient noise and higher rates of settlement of reef fish and crustaceans would provide support for the importance of ambient underwater sound in guiding the settlement of these organisms. PMID:18461369

Radford, Craig A; Jeffs, Andrew G; Tindle, Chris T; Montgomery, John C

2008-05-07

196

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.

Arenas, Ernest; Rodriguez, Francisco Javier

2012-01-01

197

Spatial and Temporal Migration Patterns of Neotropical Migrants in the Southwest Revealed by Stable Isotopes  

USGS Publications Warehouse

Executive Summary We used stable hydrogen isotopes (?D) to investigate both temporal and spatial patterns during spring migration for three warbler species, Wilson's Warbler (Wilsonia pusilla), MacGillivray's Warbler (Oporornis tolmiei), and Nashville Warbler (Vermivora ruficapilla), across multiple migration routes in southwest North America. A strong correlation between stable hydrogen isotope values of feathers and the local precipitation at sites where feathers where collected across the breeding range for all three species reaffirmed that stable hydrogen isotopes were a good predictor of breeding locations. For the Wilson's Warbler, we found a significant negative relationship between the date when warblers passed through the sampling station and ?D values of their feathers, indicating that warblers who bred the previous season at southern latitudes migrated through the migration stations earlier than did warblers that had previously bred at more northern latitudes. This pattern was consistent across their southwestern migration route (5 sites sampled) and was consistent between years. Comparing ?D values between migration stations also showed a shift towards more negative ?D values from the western to the eastern migration stations sampled in this study, which corresponded to different geographical regions of the Wilson's Warblers' western breeding range. For MacGillivray's Warbler we found the same temporal pattern as Wilson's Warbler, with warblers that bred the previous season at southern latitudes migrating through the migration stations earlier than warblers that had previously bred at more northern latitudes. This pattern was consistent at the Lower Colorado River and Arivaca Creek, the two sites where sample sizes were adequate to test these hypotheses. Comparison of the ?D between the two sites indicated that the majority of warblers migrating through these stations were breeding within a geographically limited area of MacGillivray's Warblers' overall breeding range. This is in contrast to the larger range of ?D values for Wilson's Warblers at these two sites, which corresponded to a broader area across their breeding range. Feathers were also collected across MacGillivray's Warblers' wintering range, and stable hydrogen isotope analysis indicated a significant positive relationship with wintering latitude. Because the ?D value of MacGillivray's Warblers' feathers reflects the ?D value of their breeding locations, with more negative values representing more northerly breeding latitudes, this positive relationship between feather ?D and wintering latitude indicated that warblers wintering at more southern latitudes bred at more northern latitudes. This supports a leapfrog migration system for MacGillivray's Warblers and is the first documentation of such a pattern. We did not find a temporal pattern to the spring migration of Nashville Warblers. This lack of temporal pattern could be due to the reduced size of the breeding and wintering ranges of Nashville Warblers, both of which could decrease the advantages of a temporal migration pattern. A small population of Nashville Warblers also breeds on the California coast and the sporadic nature of migration for Nashville Warblers in the southwest suggests that in some years more Nashville Warblers may winter along the California coast. The information in this study has increased our understanding of both spatial and temporal patterns of migration for three neotropical migrant birds and has important implications for understanding the ecology and evolution of migrants and factors influencing overall population dynamics.

Paxton, Kristina L.; Van Riper, Charles, III

2006-01-01

198

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

PubMed

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

2013-05-30

199

Temporal and Spatial Variability in the Migration Patterns of Juvenile and Subadult Bull Trout in Northeastern Oregon  

Microsoft Academic Search

Conservation planning for threatened bull trout Salvelinus confluentus requires the identification of temporal and spatial movement patterns to better understand the patch size and connectivity requirements of different behavioral strategies (e.g., resident and migratory) and life stages (e.g., juvenile and adult). Although these patterns have been identified for adults, less is known about the movement patterns of juvenile and subadult

Kristen Homel; Phaedra Budy

2008-01-01

200

Spatial and temporal dispersion patterns of pollinators and their relationship to the flowering strategy of Yucca whipplei (Agavaceae)  

Microsoft Academic Search

A field investigation of the mutualistic interaction between a monocarpic perennial plant, Yucca whipplei, and its host-specific pollinator and seed predator, Tegeticula maculata (Lepidoptera: Prodoxidae), was conducted to determine how the resource utilization pattern and population dynamics of the pollinator have influenced the evolution of the flowering and fruiting pattern of the plant. Although the temporal pattern of emergence of

Charles L. Aker

1982-01-01

201

Temporal analysis of feeding patterns of Culex erraticus in central Alabama.  

PubMed

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

Oliveira, Ana; Katholi, Charles R; Burkett-Cadena, Nathan; Hassan, Hassan K; Kristensen, Sibylle; Unnasch, Thomas R

2011-03-11

202

Temporal Analysis of Feeding Patterns of Culex erraticus in Central Alabama  

PubMed Central

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

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

2011-01-01

203

Temperature coupling in cricket acoustic communication  

Microsoft Academic Search

Acoustic communication in Gryllus firmus is temperature-coupled: temperature induces parallel changes in male calling song temporal pattern, and in female preference for song. Temperature effects on song production and recognition networks were localized by selectively warming head or thorax or both head and thorax of intact crickets, then eliciting aggression song production (males) or phonotaxis to synthetic calling song (females).

Anthony Pires; Ronald R. Hoy

1992-01-01

204

Temporal pattern analysis and its applicability in sport: an explanation and exemplar data.  

PubMed

Quantitative analysis of sports performance has been shown to produce information that coaches can use within the coaching process to enhance performance. Traditional methods for quantifying sport performances are limited in their capacity to describe the complex interactions of events that occur within a performance over time. In this paper, we outline a new approach to the analysis of time-based event records and real-time behaviour records on sport performance known as T-pattern detection. The relevant elements of the T-pattern detection process are explained and exemplar data from the analysis of 13 soccer matches are presented to highlight the potential of this form of analysis. The results from soccer suggest that it is possible to identify new profiles for both individuals and teams based on the analysis of temporal behavioural patterns detected within the performances. PMID:12363299

Borrie, Andrew; Jonsson, Gudberg K; Magnusson, Magnus S

2002-10-01

205

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

Microsoft Academic Search

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

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

2011-01-01

206

Movement patterns of adult red drum, Sciaenops ocellatus , in shallow Florida lagoons as inferred through autonomous acoustic telemetry  

Microsoft Academic Search

Acoustic telemetry was employed to resolve seasonal and daily movement patterns of adult red drum (Sciaenops ocellatus) in the northern Indian River Lagoon system, Florida. From May 2006 to September 2008, 44 tagged fish were tracked within\\u000a an array of 34 autonomous receivers with individuals detected for up to 654 days. Most red drum exhibited strong site fidelity\\u000a from winter through

Eric A. Reyier; Russell H. Lowers; Douglas M. Scheidt; Douglas H. Adams

2011-01-01

207

Visual map development depends on the temporal pattern of binocular activity in mice.  

PubMed

Binocular competition is thought to drive eye-specific segregation in the developing visual system, potentially through Hebbian synaptic learning rules that are sensitive to correlations in afferent activity. Altering retinal activity can disrupt eye-specific segregation, but little is known about the temporal features of binocular activity that modulate visual map development. We used optogenetic techniques to directly manipulate retinal activity in vivo and identified a critical period before eye opening in mice when specific binocular features of retinal activity drive visual map development. Synchronous activation of both eyes disrupted segregation, whereas asynchronous stimulation enhanced segregation. The optogenetic stimulus applied was spatially homogenous; accordingly, retinotopy of ipsilateral projections was markedly perturbed, but contralateral retinotopy was unaffected or even improved. These results provide direct evidence that the synchrony and precise temporal pattern of binocular retinal activity during a critical period in development regulates eye-specific segregation and retinotopy in the developing visual system. PMID:22179110

Zhang, Jiayi; Ackman, James B; Xu, Hong-Ping; Crair, Michael C

2011-11-18

208

Temporal and vertical scales of acoustic fluctuations for 75-Hz, broadband transmissions to 87-km range in the eastern North Pacific Ocean.  

PubMed

Observations of scattering of low-frequency sound in the ocean have focused largely on effects at long ranges, involving multiple scattering events. Fluctuations due to one and two scattering events are analyzed here, using 75-Hz broadband signals transmitted in the eastern North Pacific Ocean. The experimental geometry gives two purely refracted arrivals. The temporal and vertical scales of phase and intensity fluctuations for these two ray paths are compared with predictions based on the weak fluctuation theory of Munk and Zachariasen, which assumes internal-wave-induced sound-speed perturbations [J. Acoust. Soc. Am. 59, 818-838 (1976)]. The comparisons show that weak fluctuation theory describes the frequency and vertical-wave-number spectra of phase and intensity for the two paths reasonably well. The comparisons also show that a resonance condition exists between the local acoustic ray and the internal-wave field, as predicted by Munk and Zachariasen, such that only internal waves whose crests are parallel to the local ray path contribute to acoustic scattering. This effect leads to filtering of the acoustic spectra relative to the internal-wave spectra, such that steep rays do not acquire scattering contributions due to low-frequency internal waves. PMID:19739719

Colosi, John A; Xu, Jinshan; Worcester, Peter F; Dzieciuch, Matthew A; Howe, Bruce M; Mercer, James A

2009-09-01

209

A retrospective analysis of suspended solids deposition in Onondaga Lake, New York: Composition, temporal patterns, and drivers  

Microsoft Academic Search

Hurteau CA, Matthews DA, Effler SW. 2010. A retrospective analysis of suspended solids deposition in Onondaga Lake, New York: Composition, temporal patterns, and drivers. Lake Reserv. Manage. 26:43-53.Long-term and seasonal temporal patterns in the deposition of total (TSS), fixed (FSS) and volatile suspended solids (VSS) were documented for eutrophic Ca-rich Onondaga Lake, New York, for the 1980–2008 interval. Weekly collections

Craig A. Hurteau; David A. Matthews; Steven W. Effler

2010-01-01

210

Self-Organizing Neural Network Architecture for Auditory and Speech Perception with Applications to Acoustic and Other Temporal Prediction Problems.  

National Technical Information Service (NTIS)

This project is developing autonomous neural network models for the real-time perception and production of acoustic and speech signals. Our SPINET pitch model was developed to take realtime acoustic input and to simulate the key pitch data. SPINET was emb...

M. Cohen S. Grossberg

1994-01-01

211

Spatial patterns of water diffusion along white matter tracts in temporal lobe epilepsy  

PubMed Central

Objectives: Diffusion tensor imaging (DTI) tractography has shown tract-specific pathology in temporal lobe epilepsy (TLE). This technique normally yields a single value per diffusion parameter per tract, potentially reducing the sensitivity for the detection of focal changes. Our goal was to spatially characterize diffusion abnormalities of fasciculi carrying temporal lobe connections. Methods: We studied 30 patients with drug-resistant TLE and 21 healthy control subjects. Twenty-four patients underwent DTI toward the end of video-EEG telemetry, with an average of 50 ± 54 hours between the last seizure and DTI examination. After manual dissection of the uncinate and inferior longitudinal and arcuate bundle, they were spatially matched based on their distance to the temporal lobe, providing between-subject correspondence of tract segments. We evaluated point-wise differences in diffusion parameters along each tract at group and subject levels. Results: Our approach localized increased mean diffusivity restricted to or more prominent within the ipsilateral temporal lobe. These abnormalities tapered off as tracts exited the temporal lobe. We observed that the shorter the interval between the last seizure and DTI, the higher the mean diffusivity (MD) of the ipsilateral tracts. Linear discriminant analysis of tract segments correctly lateralized 87% of patients. Conclusions: The centrifugal pattern of white matter diffusion abnormalities probably reflects astrogliosis and microstructure derangement related to seizure activity in the vicinity of the focus. The negative correlation between the interval from last seizure and MD suggests a role for postictal vasogenic edema. The ability to assess tracts segmentally may contribute to a better understanding of the extent of white matter pathology in epilepsy and assist in the presurgical evaluation of patients with TLE, particularly those with unremarkable conventional imaging results.

Concha, Luis; Kim, Hosung; Bernasconi, Andrea; Bernhardt, Boris C.

2012-01-01

212

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

NASA Astrophysics Data System (ADS)

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

MacLeod, Katrina; Laurent, Gilles

1996-11-01

213

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.

214

Spatio-temporal dynamics, patterns formation and turbulence in complex fluids due to electrohydrodynamics instabilities.  

PubMed

The complex spatio-temporal dynamics generated by electrohydrodynamics instabilities in a nematic liquid crystal under the action of a driving oscillating electric field is investigated. Quasi-stationary convective structures which are visible at large scales are broken into chaotic patterns at higher driving voltages, thus generating small-scale structures. Scaling analysis reveals that these small-scale structures self-organize in a network of subleading structures which are reminescent of convective rolls. This network persists well inside the chaotic regimes, disappearing only at very high voltages, where stochastic dynamical scattering mode takes place. PMID:21805393

Carbone, F; Vecchio, A; Sorriso-Valvo, L

2011-08-03

215

Comparison of the temporal release pattern of copeptin with conventional biomarkers in acute myocardial infarction  

Microsoft Academic Search

Background  Early detection of acute myocardial infarction (AMI) using cardiac biomarkers of myocardial necrosis remains limited since\\u000a these biomarkers do not rise within the first hours from onset of AMI. We aimed to compare the temporal release pattern of\\u000a the C-terminal portion of provasopressin (copeptin) with conventional cardiac biomarkers, including creatine kinase isoenzyme\\u000a (CK-MB), cardiac troponin T (cTnT), and high-sensitivity cTnT

Youlan L. Gu; Adriaan A. Voors; Felix Zijlstra; Hans L. Hillege; Joachim Struck; Serge Masson; Tarcisio Vago; Stefan D. Anker; Ad F. M. van den Heuvel; Dirk J. van Veldhuisen; Bart J. G. L. de Smet

2011-01-01

216

Spatio–temporal VEGF and PDGF Delivery Patterns Blood Vessel Formation and Maturation  

Microsoft Academic Search

\\u000a Purpose  Biological mechanisms of tissue regeneration are often complex, involving the tightly coordinated spatial and temporal presentation\\u000a of multiple factors. We investigated whether spatially compartmentalized and sequential delivery of factors can be used to\\u000a pattern new blood vessel formation.\\u000a \\u000a \\u000a \\u000a Materials and Methods  A porous bi-layered poly(lactide–co-glycolide) (PLG) scaffold system was used to locally present vascular endothelial growth\\u000a factor (VEGF) alone in one

Ruth R. Chen; Eduardo A. Silva; William W. Yuen; David J. Mooney

2007-01-01

217

Migratory patterns of exotic brown trout Salmo trutta in south-western Hokkaido, Japan, on the basis of otolith Sr:Ca ratios and acoustic telemetry.  

PubMed

Acoustic telemetry and microchemical analysis of otolith strontium-calcium ratios were used to evaluate how exotic brown trout Salmo trutta have responded to Japanese riverine environments of south-western Hokkaido by observing their migratory patterns. The existence of anadromous S. trutta was also verified. Most S. trutta caught in rivers for otolith analysis were freshwater residents (95·6%), whereas those caught in the sea were mainly smolts (91·3%), which had just migrated from rivers during spring. Anadromous S. trutta (n = 6) were captured in rivers and in the sea, confirming the existence of mature pre- and post-spawning fish. According to telemetry results, both mature and immature S. trutta used the river in winter, and their estimated sea-run timings showed individual differences. Through the combination of these two methods, migratory patterns on various spatio-temporal scales were observed. This first documentation of the presence of both male and female anadromous S. trutta in the same region within Japan indicated the risk of further colonization of exotic S. trutta via oceanic migration. PMID:22268438

Honda, K; Arai, T; Kobayashi, S; Tsuda, Y; Miyashita, K

2012-02-01

218

Temporal and Demographic Patterns of Non-Hodgkin's Lymphoma Incidence in Pennsylvania  

PubMed Central

Objective Our study analyzed temporal and demographic patterns of non-Hodgkin’s lymphoma (NHL) incidence in Pennsylvania and compared Pennsylvania time trends with national trends. Methods Joinpoint and age-period-cohort analyses summarized sex- and race-specific NHL incidence time trends between 1985 and 2004. Ecologic analysis identified demographic factors associated with age-adjusted county-specific NHL incidence. Results NHL incidence in Pennsylvania increased annually 1.6% and 2.5% in white and black men and 1.6% and 3.2% in white and black women. National trends were similar, except for smaller increases in white men. Diffuse lymphoma appeared to be the major contributor to the increases. NHL incidence was higher in Pennsylvania counties with greater percentages of urban residents. Conclusions NHL incidence patterns in Pennsylvania were parallel to those seen nationally, with the highest rates occurring in white men and in persons residing in urban areas.

Han, Yueh-Ying; Dinse, Gregg E.; Davis, Devra L.

2010-01-01

219

Spatial and Temporal Patterns of Dengue in Guangdong Province of China.  

PubMed

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

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

2013-03-01

220

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

PubMed

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 66 dB, which could cause serious annoyance according to the World Health Organization (WHO) outdoor noise guidelines. Maximum peak noise was over 101 dB, which is close to 110 dB, the level that can cause possible hearing impairment according to the WHO guidelines. We found that noise pollution is not an environmental problem reserved for developed countries, but occurs in developing countries as well. For this reason, steps might be required to reduce noise levels caused by road traffic. PMID:20851468

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

2010-09-19

221

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.

Vincent, Olivier; Roditchev, Ivan; Marmottant, Philippe

2011-01-01

222

Spatial and temporal patterns in civil violence: Guatemala, 1977-1986.  

PubMed

Civil violence is a complex and often horrific phenomenon whose characteristics have varied by era, setting, and circumstance. Its objective analysis has rarely been feasible at spatial and temporal scales great enough and resolutions fine enough to reveal patterns useful in prevention, intervention, or adjudication. An extraordinary data set simultaneously meeting scale and resolution criteria was collected during conflict in Guatemala from 1977 through 1986. Reported here is its spatial-temporal analysis; reported as well is a putatively novel method for estimating power-law exponents from aggregate data. Analysis showed that the relationship between ethnic mix and killing was smooth yet highly nonlinear, that the temporal texture of killings was rough, and that the distribution of killing-event sizes was dichotomous, with nongenocidal and genocidal conflict periods displaying Zipf and non-Zipf distributions, respectively. These results add statistical support to claims that the Guatemalan military operated under at least two directives with respect to killing and that one of these effected a genocidal campaign against an indigenous people, the Mayans. Implications for group-behavioral modeling, conflict prevention, peace-keeping intervention, human-rights monitoring, and transitional justice are noted. PMID:16859341

Gulden, Timothy R

2002-03-01

223

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

224

Altered temporal patterns of anxiety in aged and amyloid precursor protein (APP) transgenic mice  

PubMed Central

Both normal aging and dementia are associated with dysregulation of the biological clock, which contributes to disrupted circadian organization of physiology and behavior. Diminished circadian organization in conjunction with the loss of cholinergic input to the cortex likely contributes to impaired cognition and behavior. One especially notable and relatively common circadian disturbance among the aged is “sundowning syndrome,” which is characterized by exacerbated anxiety, agitation, locomotor activity, and delirium during the hours before bedtime. Sundowning has been reported in both dementia patients and cognitively intact elderly individuals living in institutions; however, little is known about temporal patterns in anxiety and agitation, and the neurobiological basis of these rhythms remains unspecified. In the present study, we explored the diurnal pattern of anxiety-like behavior in aged and amyloid precursor protein (APP) transgenic mice. We then attempted to treat the observed behavioral disturbances in the aged mice using chronic nightly melatonin treatment. Finally, we tested the hypothesis that time-of-day differences in acetylcholinesterase and choline acetyltransferase expression and general neuronal activation (i.e., c-Fos expression) coincide with the behavioral symptoms. Our results show a temporal pattern of anxiety-like behavior that emerges in elderly mice. This behavioral pattern coincides with elevated locomotor activity relative to adult mice near the end of the dark phase, and with time-dependent changes in basal forebrain acetylcholinesterase expression. Transgenic APP mice show a similar behavioral phenomenon that is not observed among age-matched wild-type mice. These results may have useful applications to the study and treatment of age- and dementia-related circadian behavioral disturbances, namely, sundowning syndrome.

Bedrosian, Tracy A.; Herring, Kamillya L.; Weil, Zachary M.; Nelson, Randy J.

2011-01-01

225

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.

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

2012-01-01

226

Spatial and temporal patterns of bioindicator mercury in pennsylvania oak forest.  

PubMed

We monitored spatial and temporal patterns of total Hg in forest bioindicators to assess possible local, regional, and global changes in atmospheric Hg deposition. Total Hg concentrations were monitored in leaves and fresh litterfall of northern red oak ( L.), on an epiphytic moss ( Hedw.) on northern red oak stems, and in surface soil organic matter (O and O horizons) in Pennsylvania oak-dominated forests. Variously configured plots were used to monitor Hg deposition near local coal-fired generating stations and an industrial city and along an extended regional transect. Linearly decreasing temporal trends in Hg concentrations occurred in leaves, litterfall, moss, and soil O and O. Mean annual Hg concentrations were often greater near local emissions sources compared with remote areas, especially in the initial monitoring period. Decreasing time trends for different impact areas tended to converge due to greater rates of Hg decrease where initial bioindicator Hg levels were higher. Fresh litter and soil O showed the greatest overall potential as Hg bioindicators. We conclude that Hg deposition has been significantly decreasing over time throughout the study area as a result of locally and regionally declining Hg emissions. Reductions in Hg emissions are likely a co-benefit of the 1990 Clean Air Act regulations and changing industrial activities. Recent leveling of several bioindicator Hg time trends may foretell a shift in Hg depositional patterns. Mercury monitoring studies such as this fulfill a need for documenting local and regional effects of emissions reduction. PMID:23673822

McClenahen, James R; Hutnik, Russell J; Davis, Donald D

227

Temporal patterns of occupational asbestos exposure and risk of pleural mesothelioma.  

PubMed

Asbestos is the primary cause of pleural mesothelioma (PM). The objective of this study was to elucidate the importance of different temporal patterns of occupational asbestos exposure on the risk of PM using case-control data in male subjects. Cases were selected from a French case-control study conducted in 1987-1993 and the French National Mesothelioma Surveillance Program in 1998-2006. Population controls were frequency matched to cases by year of birth. Occupational asbestos exposure was evaluated with a job-exposure matrix. The dose-response relationships were estimated using restricted cubic spline functions in logistic regression models. A total of 2,466 ever-asbestos-exposed males (1,041 cases and 1,425 controls) were used. After adjustment for intensity and total duration of occupational asbestos exposure, the risk of PM was lower for subjects first exposed after the age of 20 yrs and continued to increase until 30 yrs after cessation of exposure. The effect of total duration of exposure decreased when age at first exposure and time since last exposure increased. These results, based on a large population-based case-control study, underline the need to take into account the temporal pattern of exposure on risk assessment. PMID:22075480

Lacourt, Aude; Leffondré, Karen; Gramond, Céline; Ducamp, Stéphane; Rolland, Patrick; Gilg Soit Ilg, Anabelle; Houot, Marie; Imbernon, Ellen; Févotte, Joëlle; Goldberg, Marcel; Brochard, Patrick

2011-11-10

228

Temporal speckle pattern interferometry for measuring micron-order surface motion of a liquid bridge  

NASA Astrophysics Data System (ADS)

This paper presents a technique based on temporal speckle pattern interferometry (TSPI), a new version of electronic speckle pattern interferometry (ESPI), for measuring micron-order motion of a deformable surface of a quasi-cylindrical liquid bridge. The time sequence phase method (TSPM) proposed recently has been extended to develop automated and robust procedures for temporal phase recovering of specklegrams. The performance of the procedures is verified through computer simulations made in a range of parameters involved. The technique is implemented into a TSPI system utilizing a ground glass for generating speckles from non-speckled reference and object wavefronts. The validity and accuracy of the technique are examined in the measurement of dynamic displacement of both a flat mirror and a cylindrical glass rod, where detailed comparison is made with the simultaneous measurement taken with the laser focusing displacement meter. The capability of the present technique is demonstrated by some experimental results obtained from dynamic surface displacement of a liquid bridge of silicone oil.

Li, Xinbo; Nishino, Koichi; Yoda, Shin-ichi

2004-11-01

229

Reproductive behaviour of Crocidosema (=Epinotia) aporema (Walsingham) (Lepidoptera: Tortricidae): temporal pattern of female calling and mating.  

PubMed

Crocidosema aporema (Walsingham) is a major pest of legumes in the southern cone of Latin America. The mating behaviour of two allopatric populations (Uruguay and Brazil) of C. aporema kept in captivity was studied by observing the posture of calling females, the temporal pattern of pheromone emission and mating, and the response of males to calling females in olfactometer tests. Female calling and mating was observed during the scotophase, from the first to the seventh night after adult emergence. Male response was evaluated at night using a single calling female in a Y-shaped olfactometer. Females adopted a characteristic calling posture, extruding the pheromone gland from the tip of the abdomen. Most females started calling during the second scotophase, and all females called from the third, between the fifth and seventh hours after the onset of the scotophase. Most of the couples mated once throughout the experiment, between the third and sixth night and during the middle of the dark phase. Males preferentially chose the female arm in olfactometer tests, considering both the first arm chosen and the number of visits during the observation period. Our results describe for the fi rst time the temporal pattern associated to the reproductive behaviour of C. aporema. We also provide evidence that this tortricid is monoandrous, and that pheromones are used in intersexual communication for mate finding. Our data will be used to optimize the collection of female sex pheromones for chemical characterization in order to develop a monitoring tool for this pest. PMID:20676503

Altesor, Paula; Horas, Vanusa R; Arcia, María P; Rossini, Carmen; Zarbin, Paulo H G; González, Andrés

230

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.

Florian, Razvan V.

2012-01-01

231

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

232

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

233

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

234

Altered temporal pattern of evoked afferent activity in a rat model of vincristine-induced painful peripheral neuropathy  

Microsoft Academic Search

It is known that the level of activity in nociceptive primary afferent nerve fibers increases in neuropathic conditions that produce pain, but changes in the temporal patterning of action potentials have not been analyzed in any detail. Because the patterning of action potentials in sensory nerve fibers might play a role in the development of pathological pain states, we studied

K. D Tanner; D. B Reichling; R. W Gear; S. M Paul; J. D Levine

2003-01-01

235

Gender Differences in Speech Temporal Patterns Detected Using Lagged Co-Occurrence Text-Analysis of Personal Narratives  

ERIC Educational Resources Information Center

|This paper describes a novel methodology for the detection of speech patterns. Lagged co-occurrence analysis (LCA) utilizes the likelihood that a target word will be uttered in a certain position after a trigger word. Using this methodology, it is possible to uncover a statistically significant repetitive temporal patterns of word use, compared…

Cohen, Shuki J.

2009-01-01

236

Gender Differences in Speech Temporal Patterns Detected Using Lagged Co-Occurrence Text-Analysis of Personal Narratives  

ERIC Educational Resources Information Center

This paper describes a novel methodology for the detection of speech patterns. Lagged co-occurrence analysis (LCA) utilizes the likelihood that a target word will be uttered in a certain position after a trigger word. Using this methodology, it is possible to uncover a statistically significant repetitive temporal patterns of word use, compared to…

Cohen, Shuki J.

2009-01-01

237

Short-term temporal patterns of early recruitment of coral reef fishes in the tropical eastern Pacific  

Microsoft Academic Search

Short-term temporal patterns of recruitment have been described in a variety of coral reef fishes and have often been related with lunar and tidal cycles. While the relative importance of lunar and tidal factors in determining recruitment patterns has been difficult to assess, most studies have been done in the Caribbean and Indo-Pacific, where tidal amplitudes are small. We studied

S. Lozano; F. Zapata

2003-01-01

238

Timescales of Multineuronal Activity Patterns Reflect Temporal Structure of Visual Stimuli  

PubMed Central

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

Jurjut, Ovidiu F.; Nikolic, Danko; Singer, Wolf; Yu, Shan; Havenith, Martha N.; Muresan, Raul C.

2011-01-01

239

Categorizing Temporal Patterns of Arrest in a Cohort of Adults with Serious Mental Illness  

PubMed Central

Temporal patterns of arrest among mental health systems' clientele have not been well explored. This study uses “trajectory analysis,” a methodology widely employed by criminologists exploring patterns of desistence in offending, to examine patterns of criminal justice involvement in a cohort of mental health service recipients. Data for this study are from a statewide cohort of individuals who received services from the Massachusetts Department of Mental Health in 1991 (N=13,876) and whose arrests were followed for roughly 10 years. Zero-inflated Poisson trajectory analysis applied to cohort members having two or more arrests identified five trajectories with widely varying arrest patterns. Analysis of differences in the composition of the five trajectory-based groups revealed few between-group differences in members' demographic and service use characteristics, while certain offense types were disproportionately prevalent among particular trajectory-based groups. The implications of these findings for understanding criminal justice involvement in this population and the utility of the trajectory model for system planning are discussed.

Banks, Steven M.; Roy-Bujnowski, Kristen; Grudzinskas, Albert J.; Simon, Lorna J.; Wolff, Nancy

2010-01-01

240

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

NASA Astrophysics Data System (ADS)

Larval fish settlement in estuarine nursery areas is the end result of numerous biological and physical processes. We used a numerical circulation model coupled to a particle transport model to examine the role that physics play in determining settlement patterns of red drum larvae (Sciaenops ocellatus) in nursery habitat along the Texas coast. We examined supply at various spatial scales (supply to inlet, bays, and individual settlement sites). Temporal patterns in larval settlement in Aransas Bay, Texas, are correlated with several indices of modeled particle supply (number of particles inside the bays, integrated particle input to Lydia Ann Channel, and cumulative number of competent particles in Lydia Ann Channel). High abundances of recently settled red drum in Aransas Bay result from a combination of high larval input, limited habitat for settlement, and proximity of habitat to the inlet. In contrast, larval settlement in Corpus Christi and Redfish Bays does not appear to be related to modeled measures of larval supply. Modeled particle supply at the bay-scale suggests that difference in the abundance of recently settled red drum between the bays may be related to larval supply normalized by the amount available settlement habitat within the bay.

Brown, C. A.; Jackson, G. A.; Holt, S. A.; Holt, G. J.

2005-07-01

241

“Magnetic Resonance Imaging Negative Positron Emission Tomography Positive” Temporal Lobe Epilepsy: FDG-PET Pattern Differs from Mesial Temporal Lobe Epilepsy  

Microsoft Academic Search

Purpose  Some patients with temporal lobe epilepsy (TLE) lack evidence of hippocampal sclerosis (HS) on MRI (HS-ve). We hypothesized\\u000a that this group would have a different pattern of 2-deoxy-2-[F-18]fluoro-d-glucose (FDG)-positron emission tomography (PET) hypometabolism than typical mesial TLE\\/HS patients with evidence of hippocampal\\u000a atrophy on magnetic resonance imaging (MRI) (HS+ve), with a lateral temporal neocortical rather than mesial focus.\\u000a \\u000a \\u000a \\u000a Procedures  Thirty consecutive

R. P. Carne; M. J. Cook; L. R. MacGregor; C. J. Kilpatrick; R. J. Hicks; T. J. O’Brien

2007-01-01

242

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

2012-01-23

243

Medio-Frontal and Anterior Temporal abnormalities in children with attention deficit hyperactivity disorder (ADHD) during an acoustic antisaccade task as revealed by electro-cortical source reconstruction  

PubMed Central

Background Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent disorders in children and adolescence. Impulsivity is one of three core symptoms and likely associated with inhibition difficulties. To date the neural correlate of the antisaccade task, a test of response inhibition, has not been studied in children with (or without) ADHD. Methods Antisaccade responses to visual and acoustic cues were examined in nine unmedicated boys with ADHD (mean age 122.44 ± 20.81 months) and 14 healthy control children (mean age 115.64 ± 22.87 months, three girls) while an electroencephalogram (EEG) was recorded. Brain activity before saccade onset was reconstructed using a 23-source-montage. Results When cues were acoustic, children with ADHD had a higher source activity than control children in Medio-Frontal Cortex (MFC) between -230 and -120 ms and in the left-hemispheric Temporal Anterior Cortex (TAC) between -112 and 0 ms before saccade onset, despite both groups performing similarly behaviourally (antisaccades errors and saccade latency). When visual cues were used EEG-activity preceding antisaccades did not differ between groups. Conclusion Children with ADHD exhibit altered functioning of the TAC and MFC during an antisaccade task elicited by acoustic cues. Children with ADHD need more source activation to reach the same behavioural level as control children.

2011-01-01

244

Temporal patterns of net soil N mineralization and nitrification through secondary succession in the subtropical forests of eastern China  

Microsoft Academic Search

Linking temporal trends of soil nitrogen (N) transformation with shifting patterns of plants and consequently changes of litter\\u000a quality during succession is important for understanding developmental patterns of ecosystem function. However, the successional\\u000a direction of soil N mineralization and nitrification in relation to species shifts in the subtropical regions remains little\\u000a studied. In this study, successional patterns of net soil

En-Rong Yan; Xi-Hua Wang; Ming Guo; Qiang Zhong; Wu Zhou; Yong-Fu Li

2009-01-01

245

A method for estimating the temporal and spatial patterns of carbon dioxide emissions from national fossil-fuel consumption  

Microsoft Academic Search

A proportional methodology is presented for estimating fossil-fuel consumption and concomitant anthropogenic carbon dioxide (CO2) emissions. This methodology employs data from representative sectors of the fossil-fuel market to determine the temporal (monthly) and spatial (provincial\\/state) patterns of fuel consumption. These patterns of fuel consumption are then converted to patterns of CO2 emissions. The purpose is to provide a procedure for

J. S. Gregg; Robert Joseph Andres

2008-01-01

246

Spatio-temporal dynamics of global H5N1 outbreaks match bird migration patterns.  

PubMed

The global spread of highly pathogenic avian influenza H5N1 in poultry, wild birds and humans, poses a significant pandemic threat and a serious public health risk. An efficient surveillance and disease control system relies on the understanding of the dispersion patterns and spreading mechanisms of the virus. A space-time cluster analysis of H5N1 outbreaks was used to identify spatio-temporal patterns at a global scale and over an extended period of time. Potential mechanisms explaining the spread of the H5N1 virus, and the role of wild birds, were analyzed. Between December 2003 and December 2006, three global epidemic phases of H5N1 influenza were identified. These H5N1 outbreaks showed a clear seasonal pattern, with a high density of outbreaks in winter and early spring (i.e., October to March). In phase I and II only the East Asia Australian flyway was affected. During phase III, the H5N1 viruses started to appear in four other flyways: the Central Asian flyway, the Black Sea Mediterranean flyway, the East Atlantic flyway and the East Africa West Asian flyway. Six disease cluster patterns along these flyways were found to be associated with the seasonal migration of wild birds. The spread of the H5N1 virus, as demonstrated by the space-time clusters, was associated with the patterns of migration of wild birds. Wild birds may therefore play an important role in the spread of H5N1 over long distances. Disease clusters were also detected at sites where wild birds are known to overwinter and at times when migratory birds were present. This leads to the suggestion that wild birds may also be involved in spreading the H5N1 virus over short distances. PMID:19908191

Si, Yali; Skidmore, Andrew K; Wang, Tiejun; de Boer, Willem F; Debba, Pravesh; Toxopeus, Albert G; Li, Lin; Prins, Herbert H T

2009-11-01

247

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

NASA Astrophysics Data System (ADS)

Marine reserves are the primary management tool for Guam's reef fish fishery. While a build-up of fish biomass has occurred inside reserve boundaries, it is unknown whether reserve size matches the scale of movement of target species. Using passive acoustic telemetry, we quantified movement patterns and home range size of two heavily exploited unicornfish Naso unicornis and Naso lituratus. Fifteen fish ( N. unicornis: n = 7; N. lituratus: n = 4 male, n = 4 female) were fitted with internal acoustic tags and tracked continuously over four months within a remote acoustic receiver array located in a decade-old marine reserve. This approach provided robust estimates of unicornfish movement patterns and home range size. The mean home range of 3.2 ha for N. unicornis was almost ten times larger than that previously recorded from a three-week tracking study of the species in Hawaii. While N. lituratus were smaller in body size, their mean home range (6.8 ha) was over twice that of N. unicornis. Both species displayed strong site fidelity, particularly during nocturnal and crepuscular periods. Although there was some overlap, individual movement patterns and home range size were highly variable within species and between sexes. N. unicornis home range increased with body size, and only the three largest fish home ranges extended into the deeper outer reef slope beyond the shallow reef flat. Both Naso species favoured habitat dominated by corals. Some individuals made predictable daily crepuscular migrations between different locations or habitat types. There was no evidence of significant spillover from the marine reserve into adjacent fished areas. Strong site fidelity coupled with negligible spillover suggests that small-scale reserves, with natural habitat boundaries to emigration, are effective in protecting localized unicornfish populations.

Marshell, A.; Mills, J. S.; Rhodes, K. L.; McIlwain, J.

2011-09-01

248

Overcoming interference: an fMRI investigation of pattern separation in the medial temporal lobe.  

PubMed

The medial temporal lobe (MTL) supports the formation and retrieval of long-term declarative memories, or memories for facts and everyday events. One challenge posed for this type of memory stems from the highly overlapping nature of common episodes. Within cognitive psychology, it is widely accepted that interference between information learned at different times is a major limitation on memory. In spite of several decades of intense research in the fields of interference theory and the neurobiological underpinnings of declarative memory, there is little direct evidence bearing on how the MTL resolves this interference to form accurate memories of everyday facts and events. Computational models of MTL function have proposed a mechanism in which the MTL, specifically the hippocampus, performs pattern separation, whereby overlapping representations are made less similar. However, there is little evidence bearing on how this process is carried out in the intact human MTL. Using high-resolution fMRI, we conducted a set of experiments that taxed behavioral pattern separation by using highly similar, interfering stimuli in a modified continuous recognition task. Regions within the parahippocampal gyrus demonstrated activity consistent with a "recall to reject" strategy. In contrast and critical to performing the task, activity within the hippocampus distinguished between correctly identified true stimulus repetitions, correctly rejected presentations of similar lure stimuli, and false alarms to similar lures. These data support the computational models' assertion that the hippocampus plays a key role in pattern separation. PMID:17848502

Kirwan, C Brock; Stark, Craig E L

2007-09-06

249

A descriptive analysis of temporal and spatial patterns of variability in Puget Sound oceanographic properties  

NASA Astrophysics Data System (ADS)

Temporal and spatial patterns of variability in Puget Sound's oceanographic properties are determined using continuous vertical profile data from two long-term monitoring programs; monthly observations at 16 stations from 1993 to 2002, and biannual observations at 40 stations from 1998 to 2003. Climatological monthly means of temperature, salinity, and density reveal strong seasonal patterns. Water temperatures are generally warmest (coolest) in September (February), with stations in shallow finger inlets away from mixing zones displaying the largest temperature ranges. Salinities and densities are strongly influenced by freshwater inflows from major rivers during winter and spring from precipitation and snowmelt, respectively, and variations are greatest in the surface waters and at stations closest to river mouths. Vertical density gradients are primarily determined by salinity variations in the surface layer, with stations closest to river mouths most frequently displaying the largest buoyancy frequencies at depths of approximately 4-6 m. Strong tidal stirring and reflux over sills at the entrance to Puget Sound generally removes vertical stratification. Mean summer and winter values of oceanographic properties reveal patterns of spatial connectivity in Puget Sound's three main basins; Whidbey Basin, Hood Canal, and Main Basin. Surface waters that are warmed in the summer are vertically mixed over the sill at Admiralty Inlet and advected at depth into Whidbey Basin and Hood Canal. Cooler and fresher surface waters cap these warmer waters during winter, producing temperature inversions.

Moore, Stephanie K.; Mantua, Nathan J.; Newton, Jan A.; Kawase, Mitsuhiro; Warner, Mark J.; Kellogg, Jonathan P.

2008-12-01

250

Multivariate data-driven modelling and pattern recognition for damage detection and identification for acoustic emission and acousto-ultrasonics  

NASA Astrophysics Data System (ADS)

Different methods are commonly used for non-destructive testing in structures; among others, acoustic emission and ultrasonic inspections are widely used to assess structures. The research presented in this paper is motivated by the need to improve the inspection capabilities and reliability of structural health monitoring (SHM) systems based on ultrasonic guided waves with focus on the acoustic emission and acousto-ultrasonics techniques. The use of a guided wave based approach is driven by the fact that these waves are able to propagate over relatively long distances, and interact sensitively and uniquely with different types of defect. Special attention is paid here to the development of efficient SHM methodologies. This requires robust signal processing techniques for the correct interpretation of the complex ultrasonic waves. Therefore, a variety of existing algorithms for signal processing and pattern recognition are evaluated and integrated into the different proposed methodologies. As a contribution to solve the problem, this paper presents results in damage detection and classification using a methodology based on hierarchical nonlinear principal component analysis, square prediction measurements and self-organizing maps, which are applied to data from acoustic emission tests and acousto-ultrasonic inspections. At the end, the efficiency of these methodologies is experimentally evaluated in diverse anisotropic composite structures.

Torres-Arredondo, M.-A.; Tibaduiza, D.-A.; McGugan, M.; Toftegaard, H.; Borum, K.-K.; Mujica, L. E.; Rodellar, J.; Fritzen, C.-P.

2013-10-01

251

Within-Day Temporal Patterns of Smoking, Withdrawal Symptoms, and Craving*  

PubMed Central

We examined the temporal relationships between smoking frequency and craving and withdrawal. 351 heavy smokers (?15 cigarettes per day) used ecological momentary assessment and electronic diaries to track smoking, craving, negative affect, arousal, restlessness, and attention disturbance in real time over 16 days. The waking day was divided into 8 2-hour “bins” during which cigarette counts and mean levels of craving and withdrawal were computed. Cross-sectional analyses showed no association between restlessness and smoking, and arousal and smoking, but craving (b=0.65, p<0.01) was positively associated, and negative affect (b=-0.20, p<0.01), and attention disturbance (b=-0.24, p<0.01) were inversely associated with smoking. In prospective lagged analyses, higher craving predicted more subsequent smoking and higher smoking predicted lower craving (p's < 0.01). Higher restlessness also predicted more subsequent smoking and higher smoking predicted lower restlessness (p's < 0.01). Higher negative affect did not predict later smoking, but more smoking preceded lower negative affect (p<0.01). Neither attention disturbance nor arousal predicted, or were predicted by variations in smoking. In short, smoking exhibits time-lagged, reciprocal relationships with craving and restlessness, and a one-way predictive relationship with negative affect. Temporal patterns of craving and restlessness may aid in the design of smoking cessation interventions.

Chandra, Siddharth; Scharf, Deborah; Shiffman, Saul

2011-01-01

252

Within-day temporal patterns of smoking, withdrawal symptoms, and craving.  

PubMed

We examined the temporal relationships between smoking frequency and craving and withdrawal. 351 heavy smokers (?15 cigarettes per day) used ecological momentary assessment and electronic diaries to track smoking, craving, negative affect, arousal, restlessness, and attention disturbance in real time over 16 days. The waking day was divided into 8 2-h "bins" during which cigarette counts and mean levels of craving and withdrawal were computed. Cross-sectional analyses showed no association between restlessness and smoking, and arousal and smoking, but craving (b=0.65, p<0.01) was positively associated, and negative affect (b=-0.20, p<0.01), and attention disturbance (b=-0.24, p<0.01) were inversely associated with smoking. In prospective lagged analyses, higher craving predicted more subsequent smoking and higher smoking predicted lower craving (p's<0.01). Higher restlessness also predicted more subsequent smoking and higher smoking predicted lower restlessness (p's<0.01). Higher negative affect did not predict later smoking, but more smoking preceded lower negative affect (p<0.01). Neither attention disturbance nor arousal predicted, or were predicted by variations in smoking. In short, smoking exhibits time-lagged, reciprocal relationships with craving and restlessness, and a one-way predictive relationship with negative affect. Temporal patterns of craving and restlessness may aid in the design of smoking cessation interventions. PMID:21324611

Chandra, Siddharth; Scharf, Deborah; Shiffman, Saul

2011-02-15

253

Temporal and spatial patterns of aquatic macrophyte diversity in the Upper Paraná River floodplain.  

PubMed

Although the importance of long-term data has been emphasized by ecologists in recent years, little is known about how communities may change over time. In this study, we describe the general patterns of aquatic macrophyte diversity in the Paraná River floodplain observed during six years of study. Temporal changes in community composition were also evaluated. Data on the presence or absence of aquatic macrophytes were collected between March 2002 and March 2008, in six lakes associated with three rivers. Different analytical strategies were used to evaluate the dynamics of aquatic macrophyte communities between the different systems in the floodplain. The composition of aquatic macrophytes differed among the rivers, mainly with respect to the different vegetation life forms (floating, submersed, emergent and rooted with floating stems). The temporal similarity of species composition during the six years and the beta-diversity index indicated that the month-to-month species turnover was, in general, lower in the connected lakes, which are directly influenced by the river. Probably the water level fluctuation is a selective force that contributes to maintaining diversity or richness. Our findings indicated the importance of abiotic characteristics and connectivity of the lakes in determining macrophyte composition and community stability over a long time frame. PMID:19738968

Thomaz, S M; Carvalho, P; Padial, A A; Kobayashi, J T

2009-06-01

254

Long-Term Stability of Visual Pattern Selective Responses of Monkey Temporal Lobe Neurons  

PubMed Central

Many neurons in primate inferotemporal (IT) cortex respond selectively to complex, often meaningful, stimuli such as faces and objects. An important unanswered question is whether such response selectivity, which is thought to arise from experience-dependent plasticity, is maintained from day to day, or whether the roles of individual cells are continually reassigned based on the diet of natural vision. We addressed this question using microwire electrodes that were chronically implanted in the temporal lobe of two monkeys, often allowing us to monitor activity of individual neurons across days. We found that neurons maintained their selectivity in both response magnitude and patterns of spike timing across a large set of visual images throughout periods of stable signal isolation from the same cell that sometimes exceeded two weeks. These results indicate that stimulus-selectivity of responses in IT is stable across days and weeks of visual experience.

Bondar, Igor V.; Leopold, David A.; Richmond, Barry J.; Victor, Jonathan D.; Logothetis, Nikos K.

2009-01-01

255

Temporal pattern of IGF-I expression during mouse preimplantation embryogenesis.  

PubMed

Although mouse preimplantation embryos express transcripts for the insulin-like growth factor-I receptor (IGF-IR), IGF-I transcripts were not detected by reverse transcription-PCR (RT-PCR) at any stage of preimplantation development in a previous study (Rappolee et al., Genes Dev 6:939-952, 1992). We report that IGF-I transcripts are detected in the preimplantation embryo by RT-PCR and describe the temporal pattern of expression of this transcript from the oocyte to blastocyst stages; the level declines from the oocyte to 8-cell embryo and then increases from the 8-cell to blastocyst stages. An explanation is offered to account for the differences in detecting the IGF-I transcript, and the results are discussed in the context of an autocrine/paracrine IGF-I circuit in the preimplantation mouse embryo. PMID:8129927

Doherty, A S; Temeles, G L; Schultz, R M

1994-01-01

256

Birhythmicity, Chaos, and Other Patterns of Temporal Self-Organization in a Multiply Regulated Biochemical System  

NASA Astrophysics Data System (ADS)

We analyze on a model biochemical system the effect of a coupling between two instability-generating mechanisms. The system considered is that of two allosteric enzymes coupled in series and activated by their respective products. In addition to simple periodic oscillations, the system can exhibit a variety of new modes of dynamic behavior: coexistence between two stable periodic regimes (birhythmicity), random oscillations (chaos), and coexistence of a stable periodic regime with a stable steady state (hard excitation) or with chaos. The relationship between these patterns of temporal self-organization is analyzed as a function of the control parameters of the model. Chaos and birhythmicity appear to be rare events in comparison with simple periodic behavior. We discuss the relevance of these results with respect to the regularity of most biological rhythms.

Decroly, Olivier; Goldbeter, Albert

1982-11-01

257

Remote flow sensing of complex systems: steps towards spatio-temporal prediction of flow patterns  

NASA Astrophysics Data System (ADS)

Prediction of the spatial and temporal phenomena of wind flow patterns through urban areas is investigated. Typically sparse measurements are used in wind forecasting models for updating and prediction via a method called variational data assimilation. To improve upon this method, an experimental investigation combining various measurement tools (Hot Wire Anemometry, Stereoscopic Particle Image Velocimetry SPIV), static pressure measurements and Laser Doppler Velocimetry(LDV)) is carried out to study the airflow around wall mounted obstacles in a turbulent boundary layer. The method of Proper Orthogonal Decomposition (POD) is used to decompose the flow field into a finite set of POD coefficients which vary only in time associated with a corresponding set of POD basis functions which vary only in space. Direct measurement models utilizing the measurements from SPIV and LDV, along with indirect measurement models using sparse measurements from microphones are investigated and may ultimately be combined with state-space models to obtain more robust dynamical models.

Monnier, Bruno; Mokhasi, Paritosh; Rempfer, Dietmar; Wark, Candace

2009-11-01

258

Electrophysiological evidence for a defect in the processing of temporal sound patterns in multiple sclerosis  

PubMed Central

Objectives: To assess the processing of spectrotemporal sound patterns in multiple sclerosis by using auditory evoked potentials (AEPs) to complex harmonic tones. Methods: 22 patients with definite multiple sclerosis but mild disability and no auditory complaints were compared with 15 normal controls. Short latency AEPs were recorded using standard methods. Long latency AEPs were recorded to synthesised musical instrument tones, at onset every two seconds, at abrupt frequency changes every two seconds, and at the end of a two second period of 16/s frequency changes. The subjects were inattentive but awake, reading irrelevant material. Results: Short latency AEPs were abnormal in only 4 of 22 patients, whereas long latency AEPs were abnormal to one or more stimuli in 17 of 22. No significant latency prolongation was seen in response to onset and infrequent frequency changes (P1, N1, P2) but the potentials at the end of 16/s frequency modulations, particularly the P2 peaking approximately 200 ms after the next expected change, were significantly delayed. Conclusion: The delayed responses appear to be a mild disorder in the processing of change in temporal sound patterns. The delay may be conceived of as extra time taken to compare the incoming sound with the contents of a temporally ordered sensory memory store (the long auditory store or echoic memory), which generates a response when the next expected frequency change fails to occur. The defect cannot be ascribed to lesions of the afferent pathways and so may be due to disseminated brain lesions visible or invisible on magnetic resonance imaging.

Jones, S; Sprague, L; Vaz, P

2002-01-01

259

The optimization of directivity patterns of acoustic antennas with piezoceramic rectangular bimorph transducers and flexural vibrations  

Microsoft Academic Search

To avoid the negative influence of peripheral transmission-reception during measurements, the improvement of directional characteristics of acoustic antennas using piezoceramic rectangular bimorph transducers with flexural vibrations is described. The most suitable designs of piezoceramic rectangular bimorph transducers in flexural vibration, used for various measurements, are being reviewed. The model of electromechanical vibrations for such transducers is described. Recommendations to use

A. Petrauskas

2007-01-01

260

?-Calcium calmodulin kinase II modulates the temporal structure of hippocampal bursting patterns.  

PubMed

The alpha calcium calmodulin kinase II (?-CaMKII) is known to play a key role in CA1/CA3 synaptic plasticity, hippocampal place cell stability and spatial learning. Additionally, there is evidence from hippocampal electrophysiological slice studies that this kinase has a role in regulating ion channels that control neuronal excitability. Here, we report in vivo single unit studies, with ?-CaMKII mutant mice, in which threonine 305 was replaced with an aspartate (?-CaMKII(T305D) mutants), that indicate that this kinase modulates spike patterns in hippocampal pyramidal neurons. Previous studies showed that ?-CaMKII(T305D) mutants have abnormalities in both hippocampal LTP and hippocampal-dependent learning. We found that besides decreased place cell stability, which could be caused by their LTP impairments, the hippocampal CA1 spike patterns of ?-CaMKII(T305D) mutants were profoundly abnormal. Although overall firing rate, and overall burst frequency were not significantly altered in these mutants, inter-burst intervals, mean number of intra-burst spikes, ratio of intra-burst spikes to total spikes, and mean intra-burst intervals were significantly altered. In particular, the intra burst intervals of place cells in ?-CaMKII(T305D) mutants showed higher variability than controls. These results provide in vivo evidence that besides its well-known function in synaptic plasticity, ?-CaMKII, and in particular its inhibitory phosphorylation at threonine 305, also have a role in shaping the temporal structure of hippocampal burst patterns. These results suggest that some of the molecular processes involved in acquiring information may also shape the patterns used to encode this information. PMID:22363696

Cho, Jeiwon; Bhatt, Rushi; Elgersma, Ype; Silva, Alcino J

2012-02-20

261

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.

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

2009-01-01

262

Spatio-Temporal Transmission Patterns of Black-Band Disease in a Coral Community  

PubMed Central

Background Transmission mechanisms of black-band disease (BBD) in coral reefs are poorly understood, although this disease is considered to be one of the most widespread and destructive coral infectious diseases. The major objective of this study was to assess transmission mechanisms of BBD in the field based on the spatio-temporal patterns of the disease. Methodology/Principal Findings 3,175 susceptible and infected corals were mapped over an area of 10×10 m in Eilat (northern Gulf of Aqaba, Red Sea) and the distribution of the disease was examined monthly throughout almost two full disease cycles (June 2006–December 2007). Spatial and spatio-temporal analyses were applied to infer the transmission pattern of the disease and to calculate key epidemiological parameters such as (basic reproduction number). We show that the prevalence of the disease is strongly associated with high water temperature. When water temperatures rise and disease prevalence increases, infected corals exhibit aggregated distributions on small spatial scales of up to 1.9 m. Additionally, newly-infected corals clearly appear in proximity to existing infected corals and in a few cases in direct contact with them. We also present and test a model of water-borne infection, indicating that the likelihood of a susceptible coral becoming infected is defined by its spatial location and by the relative spatial distribution of nearby infected corals found in the site. Conclusions/Significance Our results provide evidence that local transmission, but not necessarily by direct contact, is likely to be an important factor in the spread of the disease over the tested spatial scale. In the absence of potential disease vectors with limited mobility (e.g., snails, fireworms) in the studied site, water-borne infection is likely to be a significant transmission mechanism of BBD. Our suggested model of water-borne transmission supports this hypothesis. The spatio-temporal analysis also points out that infected corals surviving a disease season appear to play a major role in the re-introduction of the disease to the coral community in the following season.

Zvuloni, Assaf; Artzy-Randrup, Yael; Stone, Lewi; Kramarsky-Winter, Esti; Barkan, Roy; Loya, Yossi

2009-01-01

263

Central hemimaxillectomy and reconstruction using a superficial temporal artery axial pattern flap in a domestic short hair cat.  

PubMed

A 2-year-old, neutered male domestic short hair cat presented with a large mass involving the right upper lip and underlying gingiva. A previous attempt at mass excision had failed, and the histopathological diagnosis was reported to be a fibrosarcoma. The cat was otherwise in good health.A central hemimaxillectomy was performed with extensive soft-tissue dissection and maxillofacial reconstruction achieved using an axial pattern flap based on the superficial temporal artery. This is the first reported clinical case of the use of the superficial temporal artery axial pattern flap in the cat. Histopathology identified a periodontal fibromatous epulis. PMID:12878152

Lester, S; Pratschke, K

2003-08-01

264

Distinct temporal patterns of T cell receptor signaling during positive versus negative selection in situ.  

PubMed

The recognition by the T cell receptor (TCR) of self-peptides presented by the major histocompatibility complex (MHC) on antigen-presenting cells, such as dendritic cells and thymic epithelial cells, controls T cell fate in the thymus, with weak TCR signals inducing survival (positive selection) and stronger signals inducing death (negative selection). In vitro studies indicate that peptide ligands that induce positive selection stimulate a low, but sustained, pattern of TCR signaling; however, the temporal pattern of TCR signaling in MHC class I-restricted thymocytes (thymocytes that are presented with peptides by MHC class I) in the thymus, under conditions that support positive selection, is unknown. We addressed this question by examining intracellular Ca(2+) dynamics and migratory changes in thymocytes undergoing positive and negative selection in thymic slices. Brief, serial signaling events that were separated by migratory periods and low cytosolic Ca(2+) concentrations correlated with the positive selection of MHC class I-restricted thymocytes, whereas sustained Ca(2+) signaling and the arrest of thymocytes were associated with negative selection. Low-avidity peptides and the presentation of peptides by cortical thymic epithelial cells, rather than dendritic cells, failed to induce strong migratory arrest of thymocytes, which led to transient TCR signaling. Thus, we provide a comparison of positive and negative selection signals in situ and suggest that the absence of strong stop signals distinguishes between positive and negative selection. PMID:24129702

Melichar, Heather J; Ross, Jenny O; Herzmark, Paul; Hogquist, Kristin A; Robey, Ellen A

2013-10-15

265

Spatial and temporal patterns of nonindigenous fish introductions in the United States  

USGS Publications Warehouse

In 1978 biologists in Gainesville, Florida, began compiling records on the distribution and status of nonindigenous fishes known in U.S. inland waters. The database, now in electronic format, currently contains approximately 17,000 records representing more than 500 nonindigenous fish taxa (i.e., species, hybrids, and unidentified forms). Of these taxa, 317 (61%) are native to the United States but have been introduced by humans into U.S. drainages outside their natural geographic ranges; 185 (35%) are fishes introduced from foreign countries; and 22 (4%) are hybrids. Of the introduced foreign fish taxa, 71 (38%) are species that have established (i.e., reproducing) or possibly established populations in open U.S. waters. The database is a useful tool for natural resource managers and other decision makers. Although we periodically revise records and constantly enter new ones, our database is fairly updated; thus, we are able to more thoroughly analyze patterns of introduction and the spread of nonindigenous fishes within the United States. Moreover, information gaps exposed by the data set should serve to stimulate and guide future research on nonindigenous fishes. This paper introduces our database and provides an overview of temporal and spatial patterns of nonindigenous fish distributions in U.S. inland waters.

Nico, L. G.; Fuller, P. L.

1999-01-01

266

Direct Visualization of Spatial and Temporal Patterns of Antimicrobial Action within Model Oral Biofilms?  

PubMed Central

A microscopic method for noninvasively visualizing the action of an antimicrobial agent inside a biofilm was developed and applied to describe spatial and temporal patterns of mouthrinse activity on model oral biofilms. Three species biofilms of Streptococcus oralis, Streptococcus gordonii, and Actinomyces naeslundii were grown in glass capillary flow cells. Bacterial cells were stained with the fluorogenic esterase substrate Calcien AM (CAM). Loss of green fluorescence upon exposure to an antimicrobial formulation was subsequently imaged by time-lapse confocal laser scanning microscopy. When an antimicrobial mouthrinse containing chlorhexidine digluconate was administered, a gradual loss of green fluorescence was observed that began at the periphery of cell clusters where they adjoined the flowing bulk fluid and progressed inward over a time period of several minutes. Image analysis was performed to quantify a penetration velocity of 4 ?m/min. An enzyme-based antimicrobial formulation led to a gradual, continually slowing loss of fluorescence in a pattern that was qualitatively different from the behavior observed with chlorhexidine. Ethanol at 11.6% had little effect on the biofilm. None of these treatments resulted in the removal of biomass from the biofilm. Most methods to measure or visualize antimicrobial action in biofilms are destructive. Spatial information is important because biofilms are known for their structural and physiological heterogeneity. The CAM staining technique has the potential to provide information about the rate of antimicrobial penetration, the presence of tolerant subpopulations, and the extent of biomass removal effected by a treatment.

Takenaka, Shoji; Trivedi, Harsh M.; Corbin, Audrey; Pitts, Betsey; Stewart, Philip S.

2008-01-01

267

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

2013-09-11

268

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

2013-07-01

269

Direct visualization of spatial and temporal patterns of antimicrobial action within model oral biofilms.  

PubMed

A microscopic method for noninvasively visualizing the action of an antimicrobial agent inside a biofilm was developed and applied to describe spatial and temporal patterns of mouthrinse activity on model oral biofilms. Three species biofilms of Streptococcus oralis, Streptococcus gordonii, and Actinomyces naeslundii were grown in glass capillary flow cells. Bacterial cells were stained with the fluorogenic esterase substrate Calcien AM (CAM). Loss of green fluorescence upon exposure to an antimicrobial formulation was subsequently imaged by time-lapse confocal laser scanning microscopy. When an antimicrobial mouthrinse containing chlorhexidine digluconate was administered, a gradual loss of green fluorescence was observed that began at the periphery of cell clusters where they adjoined the flowing bulk fluid and progressed inward over a time period of several minutes. Image analysis was performed to quantify a penetration velocity of 4 mum/min. An enzyme-based antimicrobial formulation led to a gradual, continually slowing loss of fluorescence in a pattern that was qualitatively different from the behavior observed with chlorhexidine. Ethanol at 11.6% had little effect on the biofilm. None of these treatments resulted in the removal of biomass from the biofilm. Most methods to measure or visualize antimicrobial action in biofilms are destructive. Spatial information is important because biofilms are known for their structural and physiological heterogeneity. The CAM staining technique has the potential to provide information about the rate of antimicrobial penetration, the presence of tolerant subpopulations, and the extent of biomass removal effected by a treatment. PMID:18223108

Takenaka, Shoji; Trivedi, Harsh M; Corbin, Audrey; Pitts, Betsey; Stewart, Philip S

2008-01-25

270

Temporal patterns in daily measurements of inorganic and organic speciated PM2.5 in Denver  

PubMed Central

Airborne particulate matter less than 2.5 ?m in aerodynamic diameter (PM2.5) has been linked to a wide range of adverse health effects and as a result is currently regulated by the U.S. Environmental Protection Agency. PM2.5 originates from a multitude of sources and has heterogeneous physical and chemical characteristics. These features complicate the link between PM2.5 emission sources, ambient concentrations and health effects. The goal of the Denver Aerosol Sources and Health (DASH) study is to investigate associations between sources and health using daily measurements of speciated PM2.5 in Denver. The datxa set being collected for the DASH study will be the longest daily speciated PM2.5 data set of its kind covering 5.5 years of daily inorganic and organic speciated measurements. As of 2008, 4.5 years of bulk measurements (mass, inorganic ions and total carbon) and 1.5 years of organic molecular marker measurements have been completed. Several techniques were used to reveal long-term and short-term temporal patterns in the bulk species and the organic molecular marker species. All species showed a strong annual periodicity, but their monthly and seasonal behavior varied substantially. Weekly periodicities appear in many compound classes with the most significant weekday/weekend effect observed for elemental carbon, cholestanes, hopanes, select polycyclic aromatic hydrocarbons (PAHs), heavy n-alkanoic acids and methoxyphenols. Many of the observed patterns can be explained by meteorology or anthropogenic activity patterns while others do not appear to have such obvious explanations. Similarities and differences in these findings compared to those reported from other cities are highlighted.

Dutton, Steven J.; Rajagopalan, Balaji; Vedal, Sverre; Hannigan, Michael P.

2013-01-01

271

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

Microsoft Academic Search

This article describes a general framework for detecting sleepiness states on the basis of prosody, articulation, and speech-quality-related\\u000a speech characteristics. The advantages of this automatic real-time approach are that obtaining speech data is nonobstrusive\\u000a and is free from sensor application and calibration efforts. Different types of acoustic features derived from speech, speaker,\\u000a and emotion recognition were employed (frame-level-based speech features).

Jarek Krajewski; Anton Batliner; Martin Golz

2009-01-01

272

Gender Differences in Speech Temporal Patterns Detected Using Lagged Co-occurrence Text-Analysis of Personal Narratives  

Microsoft Academic Search

This paper describes a novel methodology for the detection of speech patterns. Lagged co-occurrence analysis (LCA) utilizes\\u000a the likelihood that a target word will be uttered in a certain position after a trigger word. Using this methodology, it is\\u000a possible to uncover a statistically significant repetitive temporal patterns of word use, compared to a random choice of words.\\u000a To demonstrate

Shuki J. Cohen

2009-01-01

273

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

PubMed

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

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

2013-06-01

274

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

275

Spatial and temporal patterns of coexistence between competing Aedes mosquitoes in urban Florida  

PubMed Central

Understanding mechanisms fostering coexistence between invasive and resident species is important in predicting ecological, economic, or health impacts of invasive species. The mosquito Aedes aegypti coexists at some urban sites in southeastern United States with invasive Aedes albopictus, which is often superior in interspecific competition. We tested predictions for three hypotheses of species coexistence: seasonal condition-specific competition, aggregation among individual water-filled containers, and colonization–competition tradeoff across spatially partitioned habitat patches (cemeteries) that have high densities of containers. We measured spatial and temporal patterns of abundance for both species among water-filled resident cemetery vases and experimentally positioned standard cemetery vases and ovitraps in metropolitan Tampa, Florida. Consistent with the seasonal condition-specific competition hypothesis, abundances of both species in resident and standard cemetery vases were higher early in the wet season (June) versus late in the wet season (September), but the proportional increase of A. albopictus was greater than that of A. aegypti, presumably due to higher dry-season egg mortality and strong wet-season competitive superiority of larval A. albopictus. Spatial partitioning was not evident among cemeteries, a result inconsistent with the colonization-competition tradeoff hypothesis, but both species were highly independently aggregated among standard cemetery vases and ovitraps, which is consistent with the aggregation hypothesis. Densities of A. aegypti but not A. albopictus differed among land use categories, with A. aegypti more abundant in ovitraps in residential areas compared to industrial and commercial areas. Spatial partitioning among land use types probably results from effects of land use on conditions in both terrestrial and aquatic-container environments. These results suggest that both temporal and spatial variation may contribute to local coexistence between these Aedes in urban areas.

Juliano, S. A.

2009-01-01

276

Spatial and temporal patterns of coexistence between competing Aedes mosquitoes in urban Florida.  

PubMed

Understanding mechanisms fostering coexistence between invasive and resident species is important in predicting ecological, economic, or health impacts of invasive species. The mosquito Aedes aegypti coexists at some urban sites in southeastern United States with invasive Aedes albopictus, which is often superior in interspecific competition. We tested predictions for three hypotheses of species coexistence: seasonal condition-specific competition, aggregation among individual water-filled containers, and colonization-competition tradeoff across spatially partitioned habitat patches (cemeteries) that have high densities of containers. We measured spatial and temporal patterns of abundance for both species among water-filled resident cemetery vases and experimentally positioned standard cemetery vases and ovitraps in metropolitan Tampa, Florida. Consistent with the seasonal condition-specific competition hypothesis, abundances of both species in resident and standard cemetery vases were higher early in the wet season (June) versus late in the wet season (September), but the proportional increase of A. albopictus was greater than that of A. aegypti, presumably due to higher dry-season egg mortality and strong wet-season competitive superiority of larval A. albopictus. Spatial partitioning was not evident among cemeteries, a result inconsistent with the colonization-competition tradeoff hypothesis, but both species were highly independently aggregated among standard cemetery vases and ovitraps, which is consistent with the aggregation hypothesis. Densities of A. aegypti but not A. albopictus differed among land use categories, with A. aegypti more abundant in ovitraps in residential areas compared to industrial and commercial areas. Spatial partitioning among land use types probably results from effects of land use on conditions in both terrestrial and aquatic-container environments. These results suggest that both temporal and spatial variation may contribute to local coexistence between these Aedes in urban areas. PMID:19263086

Leisnham, Paul T; Juliano, S A

2009-03-05

277

Temporal Patterns of Nitrogenase Gene (nifH) Expression in the Oligotrophic North Pacific Ocean  

PubMed Central

Dinitrogen (N2)-fixing microorganisms (diazotrophs) play important roles in ocean biogeochemistry and plankton productivity. In this study, we examined the presence and expression of specific planktonic nitrogenase genes (nifH) in the upper ocean (0 to 175 m) at Station ALOHA in the oligotrophic North Pacific Ocean. Clone libraries constructed from reverse-transcribed PCR-amplified mRNA revealed six unique phylotypes. Five of the nifH phylotypes grouped with sequences from unicellular and filamentous cyanobacteria, and one of the phylotypes clustered with ?-proteobacteria. The cyanobacterial nifH phylotypes retrieved included two sequence types that phylogenetically grouped with unicellular cyanobacteria (termed groups A and B), several sequences closely related (97 to 99%) to Trichodesmium spp. and Katagnymene spiralis, and two previously unreported phylotypes clustering with heterocyst-forming nifH cyanobacteria. Temporal patterns of nifH expression were evaluated using reverse-transcribed quantitative PCR amplification of nifH gene transcripts. The filamentous and presumed unicellular group A cyanobacterial phylotypes exhibited elevated nifH transcription during the day, while members of the group B (closely related to Crocosphaera watsonii) unicellular phylotype displayed greater nifH transcription at night. In situ nifH expression by all of the cyanobacterial phylotypes exhibited pronounced diel periodicity. The ?-proteobacterial phylotype had low transcript abundance and did not exhibit a clear diurnal periodicity in nifH expression. The temporal separation of nifH expression by the various phylotypes suggests that open ocean diazotrophic cyanobacteria have unique in situ physiological responses to daily fluctuations of light in the upper ocean.

Church, Matthew J.; Short, Cindy M.; Jenkins, Bethany D.; Karl, David M.; Zehr, Jonathan P.

2005-01-01

278

Spatial and Temporal Patterns of Aspergillus flavus Strain Composition and Propagule Density in Yuma County, Arizona, Soils  

Microsoft Academic Search

Orum, T. V., Bigelow, D. M., Nelson, M. R., Howell, D. R., and Cotty, P. J. 1997. Spatial and temporal patterns of Aspergillus flavus strain composition and propagule density in Yuma County, Arizona, soils. Plant Dis. 81:911-916. Aspergillus flavus isolates from Arizona can be divided into S and L strains on the basis of scle- rotial morphology. These genetically distinct

Thomas V. Orum; Donna M. Bigelow; Merritt R. Nelson; Donald R. Howell; Peter J. Cotty

1997-01-01

279

Preliminary study on the relationship between temporal and spatial evolution of ecological landscape pattern and climate change in Xinjiang, China  

Microsoft Academic Search

Fractional vegetation cover data (FVC) based on the annual maximum NOAA\\/AVHRR NDVI (Advanced Very High Resolution Radiometer normalized difference vegetation index) data and the ground meteorological data have been used to analyze the relationship between the temporal and spatial evolution of ecological landscape pattern and climate change in Xinjiang autonomous region, China from 1982 to 1993. It is found that

Xiaoling Pan; Xunbin Zeng; Jie Zhang; Qingdong Shi; Qing He; Qincheng Chao; Jiping Chao

2003-01-01

280

An analysis of the spatial and temporal patterns of highly pathogenic avian influenza occurrence in Vietnam using national surveillance data  

Microsoft Academic Search

The objectives of this study were to describe the spatio-temporal pattern of an epidemic of highly pathogenic avian influenza (HPAI) in Vietnam and to identify potential risk factors for the introduction and maintenance of infection within the poultry population. The results indicate that during the time period 2004–early 2006 a sequence of three epidemic waves occurred in Vietnam as distinct

Dirk U. Pfeiffer; Phan Q. Minh; Vincent Martin; Michael Epprecht; Martin J. Otte

2007-01-01

281

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

EPA Science Inventory

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

282

Spatial and temporal patterns in summer ichthyoplankton assemblages on the eastern Bering Sea shelf 1996-2000  

Microsoft Academic Search

Larval and early juvenile fishes were sampled from the eastern Bering Sea (EBS) shelf during summer from 1996 to 2000. Data from these collections were used to examine spatial and temporal patterns in species assemblage structure and abundance. Cluster analyses based on Bray-Curtis dissimilarity coefficients were used to group species and stations according to simi- lar abundance and species composition.

J. T. DUFFY-ANDERSON; M. S. BUSBY; K. L. MIER; C. M. DELIYANIDES; P. J. STABENO

2006-01-01

283

Temporal and spatial patterns of extreme low flows and effects on stream ecosystems in Otago, New Zealand  

Microsoft Academic Search

The temporal and spatial patterns of summer extreme low flows and effects on stream ecosystems were evaluated throughout the Otago Region of the South Island of New Zealand during a severe drought in 1998–1999. Flows, water quality, and aquatic biology were monitored bimonthly at 12 locations as part of a long-term regional monitoring programme and results were evaluated and compared

B. S Caruso

2002-01-01

284

Novel Analysis of Spatial and Temporal Patterns of Resource Use in a Group of Tephritid Flies of the Genus Anastrepha  

Microsoft Academic Search

The spatial and temporal patterns of oviposition-resource use of various Anastrepha spp. fruit ßies within the canopies of individual fruit trees were determined over periods of 4 Ð 6 yr in the state of Veracruz, Mexico. The ßies examined were Anastrepha obliqua (Macquart), Anastrepha striata Schiner, Anastrepha fracterculus (Wiedemann), and Anastrepha alveata Stone, and their respective hosts were Spondias mombin

John Sivinski; Martin Aluja; Jaime Piñero; Mario Ojeda

2004-01-01

285

Temporal evolution and functional outcome of no reflow: sustained and spontaneously reversible patterns following successful coronary recanalisation  

Microsoft Academic Search

Objective: To identify in humans the temporal patterns of no reflow and their functional implications.Methods: 24 patients with first acute myocardial infarction and successful coronary recanalisation by recombinant tissue-type plasminogen activator (n = 15) or primary percutaneous transluminal coronary angioplasty (n = 9) were studied by myocardial contrast echocardiography within 24 hours of recanalisation and at one month’s follow up.

L Galiuto; A Lombardo; A Maseri; L Santoro; I Porto; D Cianflone; A G Rebuzzi; F Crea

2003-01-01

286

Temporal patterns of diversity, abundance and evenness for invertebrate communities from coastal freshwater and brackish water rock pools  

Microsoft Academic Search

Aquatic invertebrate data were collected from 49 erosional, Jamaican,rock pools between 1989 and 1998 and used to describe temporal patterns ofspecies diversity. This unique series of pools on the north coast of Jamaica,classified as either brackish (31) or freshwater (18), was used to determinehowdiversity changes over time, whether there was a difference between poolclassifications, and the impacts of environmental variables.

Thomas W. Therriault

2002-01-01

287

Composition, structural characteristics and temporal patterns of fish assemblages in non-tidal Mediterranean lagoons: A case study  

Microsoft Academic Search

The importance of transitional water ecosystems as nursery habitats and feeding grounds for fish species is well-known. Detailed studies of colonization patterns of fish guilds in response to biotic and abiotic drivers are however unevenly distributed among ecosystem types. We address here the temporal variability of fish assemblages in small non-tidal lagoons in the Mediterranean basin. The study was carried

S. Maci; A. Basset

2009-01-01

288

Improvement of temporal resolution in blood concentration imaging using NIR speckle patterns  

NASA Astrophysics Data System (ADS)

In the imaging of blood concentration change using near infrared bio-speckles, temporal averaging of speckle images is necessary for speckle reduction. To improve the temporal resolution in blood concentration imaging, use of spatial averaging is investigated to measured data in rat experiments. Results show that three frames in temporal averaging with (2×2) pixels in spatial averaging can be accepted to obtain the temporal resolution of ten concentration images per second.

Yokoi, Naomichi; Shimatani, Yuichi; Kyoso, Masaki; Funamizu, Hideki; Aizu, Yoshihisa

2013-06-01

289

Dissociative patterns of foreperiod effects in temporal discrimination and reaction time tasks  

Microsoft Academic Search

This study examined whether the process of temporal preparation for a target stimulus is the same regardless of the task required by the target stimulus. To this end, the same variable-foreperiod design was used in a temporal discrimination task (Experiment 1) and a reaction time task (Experiment 2). In Experiment 1, both temporal sensitivity and perceived duration increased as a

Sander A. Los; Himeh Horoufchin

2011-01-01

290

Increased emergence of alpha activity over the left but not the right temporal lobe within a dark acoustic chamber: differential response of the left but not the right hemisphere to transcerebral magnetic fields  

Microsoft Academic Search

The percentages of alpha activity per minute over the left and right temporal lobes were measured for the first and second successive 15-min intervals while subjects wore opaque goggles within an acoustic chamber. A weak (5 ?T), burst-firing magnetic field was presented during this period for 1 s every 4 s primarily over the left or the right cerebral hemisphere.

M. A. Persinger

1999-01-01

291

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

PubMed Central

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

2011-01-01

292

Capturing spatial and temporal patterns of widespread, extreme flooding across Europe  

NASA Astrophysics Data System (ADS)

Statistical characterisation of physical hazards is an integral part of probabilistic catastrophe models used by the reinsurance industry to estimate losses from large scale events. Extreme flood events are not restricted by country boundaries which poses an issue for reinsurance companies as their exposures often extend beyond them. We discuss challenges and solutions that allow us to appropriately capture the spatial and temporal dependence of extreme hydrological events on a continental-scale, which in turn enables us to generate an industry-standard stochastic event set for estimating financial losses for widespread flooding. By presenting our event set methodology, we focus on explaining how extreme value theory (EVT) and dependence modelling are used to account for short, inconsistent hydrological data from different countries, and how to make appropriate statistical decisions that best characterise the nature of flooding across Europe. The consistency of input data is of vital importance when identifying historical flood patterns. Collating data from numerous sources inherently causes inconsistencies and we demonstrate our robust approach to assessing the data and refining it to compile a single consistent dataset. This dataset is then extrapolated using a parameterised EVT distribution to estimate extremes. Our method then captures the dependence of flood events across countries using an advanced multivariate extreme value model. Throughout, important statistical decisions are explored including: (1) distribution choice; (2) the threshold to apply for extracting extreme data points; (3) a regional analysis; (4) the definition of a flood event, which is often linked with reinsurance industry's hour's clause; and (5) handling of missing values. Finally, having modelled the historical patterns of flooding across Europe, we sample from this model to generate our stochastic event set comprising of thousands of events over thousands of years. We then briefly illustrate how this is applied within a probabilistic model to estimate catastrophic loss curves used by the reinsurance industry.

Busby, Kathryn; Raven, Emma; Liu, Ye

2013-04-01

293

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

NASA Astrophysics Data System (ADS)

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

Peleg, N.; Morin, E.

2012-04-01

294

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

SciTech Connect

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

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

2005-11-01

295

Spatio-temporal expression patterns of Arabidopsis thaliana and Medicago truncatula defensin-like genes.  

PubMed

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

Tesfaye, Mesfin; Silverstein, Kevin At; Nallu, Sumitha; Wang, Lin; Botanga, Christopher J; Gomez, S Karen; Costa, Liliana M; Harrison, Maria J; Samac, Deborah A; Glazebrook, Jane; Katagiri, Fumiaki; Gutierrez-Marcos, Jose F; Vandenbosch, Kathryn A

2013-03-18

296

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.

Sakamoto, Manabu; Ruta, Marcello

2012-01-01

297

Characterization of spatial and temporal expression pattern of SCG10 during zebrafish development  

PubMed Central

SCG10 (Superior Cervical Ganglia 10, STMN2) is a member of the stathmin family of proteins. Stathmins regulate microtubule dynamics by inhibiting polymerization and promoting their depolymerization. SCG10 is believed to be a neuronal-specific stathmin that is enriched in the growth cones of developing neurons and plays a role in regulating neurite outgrowth. In all species examined so far, SCG10 is expressed in both the CNS and PNS. We have cloned two zebrafish SCG10 homologues and have determined the temporal and spatial expression pattern of both of these genes by RT-PCR and in situ hybridization. RT-PCR shows that both transcripts are expressed maternally and zygotically through at least 5 days. In situ hybridization analysis reveals that both SCG10 orthologues have dynamic, spatial expression patterns that are nearly identical to each other. Initially, these orthologues are expressed in discrete areas of the forebrain, midbrain, and hindbrain, as well as in the anterior and posterior lateral line ganglia and transiently in the spinal cord Rohon-Beard neurons. From 48hpf onwards, the level of expression of both genes increases and becomes mainly restricted to the anterior CNS (the forebrain region, retina, optic tectum and hindbrain), and to the cranial ganglia. From 72 to 96 hpf, SCG10 genes are also expressed in the developing neurons in the gut and in the surrounding intestinal mesenchyme. Our results provide a starting point for future studies that will investigate the in vivo function of SCG10 orthologues in zebrafish neural development.

Burzynski, Grzegorz M.; Delalande, Jean-Marie; Shepherd, Iain

2009-01-01

298

Characterization of spatial and temporal expression pattern of SCG10 during zebrafish development.  

PubMed

SCG10 (Superior Cervical Ganglia 10, STMN2) is a member of the stathmin family of proteins. Stathmins regulate microtubule dynamics by inhibiting polymerization and promoting their depolymerization. SCG10 is believed to be a neuronal-specific stathmin that is enriched in the growth cones of developing neurons and plays a role in regulating neurite outgrowth. In all species examined so far, SCG10 is expressed in both the CNS and PNS. We have cloned two zebrafish SCG10 homologues and have determined the temporal and spatial expression pattern of both of these genes by RT-PCR and in situ hybridization. RT-PCR shows that both transcripts are expressed maternally and zygotically through at least 5 days. In situ hybridization analysis reveals that both SCG10 orthologues have dynamic, spatial expression patterns that are nearly identical to each other. Initially, these orthologues are expressed in discrete areas of the forebrain, midbrain, and hindbrain, as well as in the anterior and posterior lateral line ganglia and transiently in the spinal cord Rohon-Beard neurons. From 48hpf onwards, the level of expression of both genes increases and becomes mainly restricted to the anterior CNS (the forebrain region, retina, optic tectum, and hindbrain), and to the cranial ganglia. From 72 to 96hpf, SCG10 genes are also expressed in the developing neurons in the gut and in the surrounding intestinal mesenchyme. Our results provide a starting point for future studies that will investigate the in vivo function of SCG10 orthologues in zebrafish neural development. PMID:19272335

Burzynski, Grzegorz M; Delalande, Jean-Marie; Shepherd, Iain

2009-01-19

299

Geographic and temporal patterns of recurrent intentional injury in south-central Los Angeles.  

PubMed Central

To better understand geographic and temporal patterns of recurrent intentional injury, 285 consecutive trauma patients were evaluated prospectively. Fifteen were excluded because of immediate death or severe brain injury. The remaining 270 patients were interviewed. Of these, 59 (22%) had been treated in a hospital for a total of 75 previous episodes of intentional trauma (mean: 1.3 episodes/patient). In 66 of the 75 episodes, the patient recalled where treatment had been received (88%). Twenty-eight (42%) of the 66 episodes had been treated at King/Drew Medical Center (KDMC), 36 (55%) had been treated at a hospital within a 3-mile radius of KDMC, 48 (73%) within an 8-mile radius, and 63 (95%) within a 10-mile radius. Sixty-five percent of the episodes occurred 5 years or less prior to the current injury (range: 11 days to 30 years; mean: 4.9 years). Patients currently admitted for intentional injury were more likely to have had intentional injury previously than those with unintentional injury (27% versus 12%). Based on these findings, we conclude that intentional trauma patients in our community remain in a defined geographic region and that there is a definable high-risk period for recurrent intentional injury. These conclusions should enhance the development of a framework on which future violence prevention programs can be designed.

Kennedy, F.; Brown, J. R.; Brown, K. A.; Fleming, A. W.

1996-01-01

300

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

2012-07-28

301

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.

Abaid, Nicole; Porfiri, Maurizio

2010-01-01

302

Spatial and Temporal Patterns of Lin-12 Expression during C. Elegans Hermaphrodite Development  

PubMed Central

The lin-12 gene encodes a receptor that mediates certain cell-cell interactions during Caenorhabditis elegans development. We have examined the expression of a lin-12::lacZ reporter gene in individual cells during the development of C. elegans hermaphrodites. lin-12::lacZ is expressed in a discrete spatial and temporal pattern during development and the lin-12::lacZ reporter gene will provide a useful marker for other studies, particularly of somatic gonadal and vulval development. In general, the cells that express lin-12::lacZ correspond to cells whose fates are known to be altered in lin-12 mutants implying that restriction of lin-12 expression may be an important regulatory mechanism; the exceptions to this statement may reveal the cellular defects that underlie aspects of the lin-12 phenotype that have not been previously explained. For decisions that are not naturally variable, lin-12::lacZ expression does not appear to change before or upon commitment to a cell fate implying that in these cases posttranscriptional regulation of lin-12 activity may control cell fate specification.

Wilkinson, H. A.; Greenwald, IVA.

1995-01-01

303

Temporal and Spatial Expression Pattern of Sucrose Synthase during Tomato Fruit Development.  

PubMed Central

Sucrose synthase is proposed to play an important role in the early stages of tomato fruit (Lycopersicon esculentum Mill.) growth. In this work, the temporal and spatial expression patterns of sucrose synthase during tomato fruit development were investigated. Fruit contained the majority of the sucrose synthase protein and mRNA relative to other organs. Only trace levels of sucrose synthase protein and mRNA were detected in the stem, petiole, and roots. Sucrose synthase mRNA was detected in pistils prior to anthesis, reached peak levels in fruit 5 to 7 d after anthesis (DAA), and was not detectable after 35 DAA. Sucrose synthase protein levels reached a maximum at 20 to 25 DAA and then declined to nondetectable levels after 45 DAA. The lack of coordination between protein and mRNA levels suggests that sucrose synthase expression may be controlled at the levels of both transcription and translation. Sucrose synthase mRNA was differentially localized in the fruit, being most abundant in the mesocarp cells adjacent to the placenta, the columella, and the cells surrounding the vascular bundle. Except around the vascular tissue, the localization of sucrose synthase mRNA positively correlates with starch granule accumulation at the cellular level.

Wang, F.; Smith, A. G.; Brenner, M. L.

1994-01-01

304

Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes  

NASA Astrophysics Data System (ADS)

Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes) than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale) and binary indicator maps (for the long-term and hillslope scale). Annual dynamics of soil moisture and decimeter-scale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a data-scarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to self-reinforcing flow paths.

Blume, T.; Zehe, E.; Bronstert, A.

2009-07-01

305

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

306

Tinnitus behavior and hearing function correlate with the reciprocal expression patterns of BDNF and Arg3.1\\/arc in auditory neurons following acoustic trauma  

Microsoft Academic Search

The molecular changes following sensory trauma and the subsequent response of the CNS are poorly understood. We focused on finding a molecular tool for monitoring the features of excitability which occur following acoustic trauma to the auditory system. Of particular interest are genes that alter their expression pattern during activity-induced changes in synaptic efficacy and plasticity. The expression of brain-derived

J. Tan; L. Rüttiger; R. Panford-Walsh; W. Singer; H. Schulze; S. B. Kilian; S. Hadjab; U. Zimmermann; I. Köpschall; K. Rohbock; M. Knipper

2007-01-01

307

The social organization of resident-type killer whales ( Orcinus orca) in Avacha Gulf, Northwest Pacific, as revealed through association patterns and acoustic similarity  

Microsoft Academic Search

Northeast Pacific resident-type killer whales (Orcinus orca) are known to form stable associations based on kinship between maternal relatives (matrilines) with a system of vocal dialects thought to reflect kinship relationships. We analyzed association patterns and acoustic similarity to study the social organization of killer whales in Avacha Gulf (Kamchatka, Russia), in the Northwest Pacific. The resident-type killer whales of

Tatiana Ivkovich; Olga A. Filatova; Alexandr M. Burdin; Hal Sato; Erich Hoyt

2010-01-01

308

Gender differences in speech temporal patterns detected using lagged co-occurrence text-analysis of personal narratives.  

PubMed

This paper describes a novel methodology for the detection of speech patterns. Lagged co-occurrence analysis (LCA) utilizes the likelihood that a target word will be uttered in a certain position after a trigger word. Using this methodology, it is possible to uncover a statistically significant repetitive temporal patterns of word use, compared to a random choice of words. To demonstrate this new tool on autobiographical narratives, 200 subjects related each a 5-min story, and these stories were transcribed and subjected to LCA, using software written by the author. This study focuses on establishing the usefulness of LCA in psychological research by examining its associations with gender. The application of LCA to the corpus of personal narratives revealed significant differences in the temporal patterns of using the word "I" between male and female speakers. This finding is particularly demonstrative of the potential for studying speech temporal patterns using LCA, as men and women tend to utter the pronoun "I" in comparable frequencies. Specifically, LCA of the personal narratives showed that, on average, men tended to have shorter interval between their use of the pronoun, while women speak longer between two subsequent utterances of the pronoun. The results of this study are discussed in light of psycholinguistic factors governing male and female speech communities. PMID:19043784

Cohen, Shuki J

2008-11-29

309

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

310

Ductal carcinoma in situ: trends in geographic, temporal, and demographic patterns of care and survival.  

PubMed

While long-term prognosis is excellent, treatment of ductal carcinoma in situ (DCIS) remains controversial and inconsistent. The purpose of this study was to track geographic and temporal patterns of care for women diagnosed with DCIS, and analyze subsequent cancer-specific risk of mortality. Subjects for this study were 41,245 women diagnosed with primary DCIS in the National Surveillance, Epidemiology, and End Results (SEER) program from 1973 through 2000. Variables analyzed included patient age, year of diagnosis, SEER site of residence at the time of diagnosis, treatment (surgery, radiation), race, age, and hormone (estrogen and progesterone) receptor status. The percentage of women diagnosed with DCIS out of the total number of women diagnosed with breast cancer increased steadily between 1973 and 2000, with the largest increase occurring around 1985. Breast conserving surgery (BCS) utilization increased over time for each SEER site to the current proportions, ranging from 49.5% in Utah to 76.9% in Connecticut. Younger women were significantly more likely to receive mastectomy and had significantly lower risk of death. Women receiving BCS who also had radiation therapy (RT) had a significantly lower risk of death, although those receiving mastectomy had the lowest risk of death. Black women and Asian/Pacific island women were significantly more likely to receive BCS, although black women were less likely to receive follow-up RT and had a significantly increased risk of death. Racial and age differences in the treatment of DCIS resulted in significantly disparate rates of survival, which should be considered in public health programming. Mastectomy utilization resulted in improved survival, although additional studies may elucidate the interaction of treatment with patient age. PMID:16409583

Joslyn, Sue A

311

Exploring spatio-temporal patterns of mortality using mixed effects models.  

PubMed

A linear mixed effects (LME) model previously used for a spatial analysis of mortality data for a single time period is extended to include time trends and spatio-temporal interactions. This model includes functions of age and time period that can account for increasing and decreasing death rates over time and age, and a change-point of rates at a predetermined age. A geographic hierarchy is included that provides both regional and small area age-specific rate estimates, stabilizing rates based on small numbers of deaths by sharing information within a region. The proposed log-linear analysis of rates allows the use of commercially available software for parameter estimation, and provides an estimator of overdispersion directly as the residual variance. Because of concerns about the accuracy of small area rate estimates when there are many instances of no observed deaths, we consider potential sources of error, focusing particularly on the similarity of likelihood inferences using the LME model for rates as compared to an exact Poisson-normal mixed effects model for counts. The proposed LME model is applied to breast cancer deaths which occurred among white women during 1979-1996. For this example, application of diagnostics for multiparameter likelihood comparisons suggests a restriction of age to a minimum of either 25 or 35, depending on whether small area rate estimates are required. Investigation into a convergence problem led to the discovery that the changes in breast cancer geographic patterns over time are related more to urbanization than to region, as previously thought. Published in 2000 by John Wiley & Sons, Ltd. PMID:10960851

Pickle, L W

312

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

313

Temporal patterns of nitrogen leakage from mid-Appalachian forested watersheds: Role of insect defoliation  

NASA Astrophysics Data System (ADS)

Fluxes of dissolved nitrogen (N) as nitrate from forested watersheds in the mid-Appalachian region have important water quality ramifications for small acid-sensitive streams and for downstream receiving waters such as the Chesapeake Bay. Previous studies of N leakage have suggested that annual dissolved N fluxes from small watersheds can vary by several orders of magnitude and may be increasing as second-growth forests gradually become N saturated from the accrual of atmospheric N loadings. In this study, we examined the temporal (intra-annual and interannual) variability in dissolved nitrate fluxes from five small (area < 15 km2) forested watersheds in the mid-Appalachian region from 1988 to 1995. At all sites, nitrate concentrations were observed to increase dramatically during storm flow events, with nitric acid contributing significantly to depressions in pH and acid-neutralizing capacity; annual nitrate fluxes were dominated by high-discharge periods. Interannually, the fluxes at each site varied by 1-2 orders of magnitude, but the patterns of N leakage displayed considerable synchrony with outbreaks of gypsy moth caterpillar defoliation that began in the late 1980s and early 1990s in this region. N leakage from forested watersheds apparently lagged the initial defoliation by several months to perhaps a year or more. Defoliation outbreaks by the gypsy moth caterpillar (or other herbivorous pests) thus provide an alternative explanation of N leakage from forest ecosystems. Poorly documented insect defoliations, rather than premature N saturation of intact forest ecosystems, need to be considered as a possible explanation of N leakage from forested watersheds in the mid-Appalachian region and elsewhere.

Eshleman, Keith N.; Morgan, Raymond P.; Webb, James R.; Deviney, Frank A.; Galloway, James N.

1998-08-01

314

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.

Olson, Karen L.; Mandl, Kenneth D.

2012-01-01

315

Learning of Temporal Motor Patterns: An Analysis of Continuous Versus Reset Timing  

PubMed Central

Our ability to generate well-timed sequences of movements is critical to an array of behaviors, including the ability to play a musical instrument or a video game. Here we address two questions relating to timing with the goal of better understanding the neural mechanisms underlying temporal processing. First, how does accuracy and variance change over the course of learning of complex spatiotemporal patterns? Second, is the timing of sequential responses most consistent with starting and stopping an internal timer at each interval or with continuous timing? To address these questions we used a psychophysical task in which subjects learned to reproduce a sequence of finger taps in the correct order and at the correct times – much like playing a melody at the piano. This task allowed us to calculate the variance of the responses at different time points using data from the same trials. Our results show that while “standard” Weber’s law is clearly violated, variance does increase as a function of time squared, as expected according to the generalized form of Weber’s law – which separates the source of variance into time-dependent and time-independent components. Over the course of learning, both the time-independent variance and the coefficient of the time-dependent term decrease. Our analyses also suggest that timing of sequential events does not rely on the resetting of an internal timer at each event. We describe and interpret our results in the context of computer simulations that capture some of our psychophysical findings. Specifically, we show that continuous timing, as opposed to “reset” timing, is consistent with “population clock” models in which timing emerges from the internal dynamics of recurrent neural networks.

Laje, Rodrigo; Cheng, Karen; Buonomano, Dean V.

2011-01-01

316

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

317

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

318

Radiative heating of acoustically levitated nano-silica droplets: Internal flow pattern leading to ring or bowl shaped structure  

NASA Astrophysics Data System (ADS)

An experimental setup using radiative heating has been used to understand the thermophysical phenomena inside acoustically levitated droplets. In this transformation process, through IR thermography and high speed imaging, events such as vaporization, precipitation have been recorded at high temporal resolution; leading to bowl or ring shaped structures. High solute loading is seen to form high concentration precipitate near the surface with a weak center linkage which results in a horizontal ring formation initially. Droplet recirculation is more effective at lower concentrations, inducing a bridge formation near the center leading to a bowl formation. With non-uniform particle distribution, these structures can experience rupture which modifies the droplet rotational speed with preferential orientation. PIV on sub millimeter sized droplets shows presence of strong single core vortex around droplet center. Study with droplet diameter and viscosity of the liquid leads to the conclusion that the strength of the vortex is dependent on these parameters. Further investigation with LIF confirms preferential accumulation of particles at the bottom of the droplet.

Saha, Abhishek; Tijerino, Erick; Kumar, Ranganathan; Basu, Saptarshi

2010-11-01

319

Temporal Variability and Stability in Infant-Directed Sung Speech: Evidence for Language-Specific Patterns  

ERIC Educational Resources Information Center

In this paper, sung speech is used as a methodological tool to explore temporal variability in the timing of word-internal consonants and vowels. It is hypothesized that temporal variability/stability becomes clearer under the varying rhythmical conditions induced by song. This is explored cross-linguistically in German--a language that exhibits a…

Falk, Simone

2011-01-01

320

Temporal Variability and Stability in Infant-Directed Sung Speech: Evidence for Language-Specific Patterns  

ERIC Educational Resources Information Center

|In this paper, sung speech is used as a methodological tool to explore temporal variability in the timing of word-internal consonants and vowels. It is hypothesized that temporal variability/stability becomes clearer under the varying rhythmical conditions induced by song. This is explored cross-linguistically in German--a language that exhibits…

Falk, Simone

2011-01-01

321

Spatio-temporal patterns of historical shallow landslides in a volcanic area, Mt. Aso, Japan  

Microsoft Academic Search

The evaluation of spatially and temporally distributed records of translational shallow landslides in heterogeneous watersheds provides insights needed to understand disastrous processes. Recurrent slope instability events occurred between 1953 and 1998 in two watersheds of Mt. Aso, western Japan. This paper investigates (1) the spatio-temporal characteristics of translational shallow landslides (dimensions, numbers, densities, and area subjected to failure) observed at

Prem P. Paudel; H. Omura; T. Kubota; T. Inoue

2007-01-01

322

Spatio-temporal Patterning of Small Area Low Birth Weight Incidence and Its Correlates: A Latent Spatial Structure Approach  

PubMed Central

Low birth weight (LBW) defined as infant weight at birth of less than 2500g is a useful health outcome for exploring spatio-temporal variation and the role of covariates. LBW is a key measure of population health used by local, national and international health organizations. Yet its spatio-temporal patterns and their dependence structures are poorly understood. In this study we examine the use of flexible latent structure models for the analysis of spatio-temporal variation in LBW. Beyond the explanatory capabilities of well-known predictors, we observe spatio-temporal effects, which are not directly observable using conventional modeling approaches. Our analysis shows that for county-level counts of LBW in Georgia and South Carolina the proportion of black population is a positive risk factor while high-income is a negative risk factor. Two dominant residual temporal components are also estimated. Finally our proposed method provides a better goodness-of-fit to these data than the conventional space-time models.

Kirby, Russell S.; Liu, Jihong; Lawson, Andrew B.; Choi, Jungsoon; Cai, Bo; Hossain, Md Monir

2011-01-01

323

Meal patterns and obesity in Swedish women–a simple instrument describing usual meal types, frequency and temporal distribution  

Microsoft Academic Search

Objective: To characterize meal patterns in relation to obesity in Swedish women using a simple instrument describing meal frequency, meal types and temporal distribution.Design: Cross-sectional parallel group design.Subjects: Eighty-three obese women from the Swedish Obese Subjects (SOS) study were compared with 94 reference women, randomly recruited from the population.Method: A new, simplified and self-instructing questionnaire was used to assess meal

H Bertéus Forslund; AK Lindroos; L Sjöström; L Lissner

2002-01-01

324

Multiple, Distant Gata2 Enhancers Specify Temporally and Tissue-Specific Patterning in the Developing Urogenital System  

Microsoft Academic Search

Transcription factor GATA-2 is expressed in a complex temporally and tissue-specific pattern within the developing embryo. Loss-of-function studies in the mouse showed that GATA-2 activity is first required during very early hematopoiesis. We subsequently showed that a 271-kbp yeast artificial chromosome (YAC) transgene could fully complement the loss of Gata2 hematopoietic function but that these YAC-rescued Gata2 null mutant mice

Melin Khandekar; Norio Suzuki; Jon Lewton; Masayuki Yamamoto; James Douglas Engel

2004-01-01

325

Estimating spatial and temporal patterns of urban anthropogenic heat fluxes for UK cities: the case of Manchester  

Microsoft Academic Search

A model is proposed for determining the temporal and spatial patterns of anthropogenic heat fluxes in UK urban areas. It considers\\u000a buildings, traffic, and metabolic heat flux sources and has been evaluated to a good accuracy against alternative data for\\u000a the Greater Manchester area in the UK. Results are presented at spatial resolution of 200 ×?200 m although the model itself\\u000a is

Claire Smith; Sarah Lindley; Geoff Levermore

2009-01-01

326

Pattern electroretinograms for the detection of neural loss in patients with permanent temporal visual field defect from chiasmal compression  

Microsoft Academic Search

Purpose To evaluate the ability of full-field and hemifield pattern electroretinogram (PERG) parameters to differentiate between\\u000a healthy eyes and eyes with band atrophy (BA) of the optic nerve. Methods Twenty-six eyes from 26 consecutive patients with permanent temporal hemianopic visual field defects and BA of the optic nerve\\u000a from previous chiasmal compression and 26 healthy subjects were studied prospectively. All

Leonardo P. Cunha; Maria K. Oyamada; Mário L. R. Monteiro

2008-01-01

327

Spatio-temporal patterns of tree community dynamics in a tropical forest fragment in South-east Brazil  

Microsoft Academic Search

The tree community (dbh > 5 cm) of a fragment of tropical montane semi-deciduous forest in South-east Brazil was repeatedly\\u000a surveyed over a 19-year period in order to assess spatial and temporal patterns of dynamics. The surveys took place in 1987,\\u000a 1992, 1996, 2001, and 2006 in a grid of 126 20 × 20 m permanent plots covering almost the entire fragment (5.8 ha). Overall\\u000a patterns indicated

Pedro Higuchi; Ary T. Oliveira-Filho; Daniel P. Bebber; Nick D. Brown; Ana Carolina Silva; Evandro L. M. Machado

2008-01-01

328

Temporal patterns of deep brain stimulation generated with a true random number generator and the logistic equation: effects on CNS arousal in mice  

PubMed Central

Deep brain stimulation (DBS) has shown promise in the treatment of many neurological and psychiatric disorders as well as a disorder of consciousness, the minimally conscious state (MCS). In the clinic, DBS is always monotonic standard pulses; however, we have hypothesized that temporally patterned pulses might be more efficient in achieving desired behavioral responses. Here we present two experiments on DBS of the central thalamus to increase arousal, as measured by motor activity, and to affect the electroencephalogram (EEG). In the first, we optimized amplitude and frequency in standard stimulation of the central thalamus in intact mice. In the second, the optimized fixed frequency was compared to two alternative temporal patterns, chaotic and random, which were physically identical to each other and fixed frequency in all ways except temporal pattern. In both experiments and with all types of stimulation, DBS of the central thalamus increased arousal as measured by motor activity. These data also revealed that temporal patterning of pulses can modulate response to stimulation. That temporal patterns in DBS of the central thalamus were found to alter motor activity response implies possible usefulness of temporal patterns in DBS of other contexts. More investigation into exactly how temporally patterned stimulation may affect neuronal circuit dynamics is necessary.

Quinkert, A. W.; Pfaff, D. W.

2012-01-01

329

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.

Diehl, Joshua John; Paul, Rhea

2011-01-01

330

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

331

Studies of Small Whales Movement Patterns Using Satellite and Acoustic Towed Array Technology.  

National Technical Information Service (NTIS)

The primary objective of this study was to design and evaluate a Wood-Ivey Systems, PTT model 165 ARGOS satellite transmitter for housing in a package suitable for mounting on a small odontocete whale for study of its long-term movement patterns. The prev...

W. E. Evans

1984-01-01

332

Incorporation of treatment plan spatial and temporal dose patterns into a prostate intrafractional motion management strategy  

SciTech Connect

Purpose: Periodic MV/KV radiographs taken during volumetric modulated arc therapy (VMAT) for hypofractionated treatment provide guidance in intrafractional motion management. The choice of imaging frequency and timing are key components in delivering the desired dose while reducing associated overhead such as imaging dose, preparation, and processing time. In this project the authors propose a paradigm with imaging timing and frequency based on the spatial and temporal dose patterns of the treatment plan. Methods: A number of control points are used in treatment planning to model VMAT delivery. For each control point, the sensitivity of individual target or organ-at-risk dose to motion can be calculated as the summation of dose degradations given the organ displacements along a number of possible motion directions. Instead of acquiring radiographs at uniform time intervals, MV/KV image pairs are acquired indexed to motion sensitivity. Five prostate patients treated via hypofractionated VMAT are included in this study. Intrafractional prostate motion traces from the database of an electromagnetic tracking system are used to retrospectively simulate the VMAT delivery and motion management. During VMAT delivery simulation patient position is corrected based on the radiographic findings via couch movement if target deviation violates a patient-specific 3D threshold. The violation rate calculated as the percentage of traces failing the clinical dose objectives after motion correction is used to evaluate the efficacy of this approach. Results: Imaging indexed to a 10 s equitime interval and correcting patient position accordingly reduces the violation rate to 19.5% with intervention from 44.5% without intervention. Imaging indexed to the motion sensitivity further reduces the violation rate to 12.1% with the same number of images. To achieve the same 5% violation rate, the imaging incidence can be reduced by 40% by imaging indexed to motion sensitivity instead of time. Conclusions: The simulation results suggest that image scheduling according to the characteristics of the treatment plan can improve the efficiency of intrafractional motion management. Using such a technique, the accuracy of delivered dose during image-guided hypofractionated VMAT treatment can be improved.

Zhang Pengpeng; Hunt, Margie; Happersett, Laura; Cox, Brett; Mageras, Gig [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States)

2012-09-15

333

Temporal patterns of broad isoform expression during the development of neuronal lineages in Drosophila  

PubMed Central

Background During the development of the central nervous system (CNS) of Drosophila, neuronal stem cells, the neuroblasts (NBs), first generate a set of highly diverse neurons, the primary neurons that mature to control larval behavior, and then more homogeneous sets of neurons that show delayed maturation and are primarily used in the adult. These latter, 'secondary' neurons show a complex pattern of expression of broad, which encodes a transcription factor usually associated with metamorphosis, where it acts as a key regulator in the transitions from larva and pupa. Results The Broad-Z3 (Br-Z3) isoform appears transiently in most central neurons during embryogenesis, but persists in a subset of these cells through most of larval growth. Some of the latter are embryonic-born secondary neurons, whose development is arrested until the start of metamorphosis. However, the vast bulk of the secondary neurons are generated during larval growth and bromodeoxyuridine incorporation shows that they begin expressing Br-Z3 about 7 hours after their birth, approximately the time that they have finished outgrowth to their initial targets. By the start of metamorphosis, the oldest secondary neurons have turned off Br-Z3 expression, while the remainder, with the exception of the very youngest, maintain Br-Z3 while they are interacting with potential partners in preparation for neurite elaboration. That Br-Z3 may be involved in early sprouting is suggested by ectopically expressing this isoform in remodeling primary neurons, which do not normally express Br-Z3. These cells now sprout into ectopic locations. The expression of Br-Z3 is transient and seen in all interneurons, but two other isoforms, Br-Z4 and Br-Z1, show a more selective expression. Analysis of MARCM clones shows that the Br-Z4 isoform is expressed by neurons in virtually all lineages, but only in those cells born during a window during the transition from the second to the third larval instar. Br-Z4 expression is then maintained in this temporal cohort of cells into the adult. Conclusion These data show the potential for diverse functions of Broad within the developing CNS. The Br-Z3 isoform appears in all interneurons, but not motoneurons, when they first begin to interact with potential targets. Its function during this early sorting phase needs to be defined. Two other Broad isoforms, by contrast, are stably expressed in cohorts of neurons in all lineages and are the first examples of persisting molecular 'time-stamps' for Drosophila postembryonic neurons.

2009-01-01

334

Effects of speed on temporal patterns in classical style and freestyle cross-country skiing.  

PubMed

The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross-country skiing techniques. Eight skilled male cross-country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross-country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self-selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross-country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross-country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross-country skiing techniques. PMID:15079990

Nilsson, Johnny; Tveit, Per; Eikrehagen, Olav

2004-01-01

335

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

PubMed Central

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 101 public ART hospitals treated 44,446 patients and the 91 ART health centers treated 1,599 patients in December 2006. The number of patients currently receiving ART doubled between February and December 2006 and the number of female patients aged 15 years and older surpassed male patients, apparently due to increased awareness and provision of free ART. Of 58,405 patients who ever started ART in December 2006, 46,045 (78.8%) were adhering to treatment during that month. Population coverage of ART was highest in the three urban administrative regions of Addis Ababa, Harari and Dire Dawa, in regional centers with referral hospitals, and in several small road side towns that had former mission or other NGO-operated hospitals. Hospitals in Addis Ababa had the largest patient loads (on average 850 patients) and those in SNNPR (Southern Nations and Nationalities Peoples Republic) (212 patients) and Somali (130 patients) regions the fewest patients. In bivariate tests, number of patients receiving treatment was significantly correlated with population size of towns, urban population per zone, number of hospitals per zone, and duration of ART services in 2006 (all p < 0.001). The stronger relationship with urban than total zonal populations (p < 0.001 versus p = 0.014) and the positive correlation between distance from 44 health centers to the nearest ART hospital and patients receiving treatment at these health centers may be due to a combination of differential accessibility of ART sites, patient knowledge and health-seeking behavior. Conclusion The sharp increase in ART uptake in 2006 is largely due to the rapid increase in the provision of free treatment at more sites. The marked variation in ART utilization patterns between urban and rural communities and among zones and regions requires further studies. Recommendations are made for further expansion and sustainability of the ART scale-up.

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

2007-01-01

336

Patterns of venom production and temporal polyethism in workers of Jerdon's jumping ant, Harpegnathos saltator.  

PubMed

Ants are chemical factories, and among their more noticeable products are their venoms. Though many studies have addressed the properties and activities of ant venoms, basic venom-related physiological questions, such as how venom production and replacement may vary with age, are rarely addressed. The answers to these questions are fundamental to understanding the physiological capabilities of these organisms, as well as the parameters within which potential optimization of their investment in venom production must take place. The only previous investigation into venom production in ants found it to be limited to early life in workers of the fire ant, Solenopsis invicta (Haight and Tschinkel, 2003). Because similar studies have not been conducted for comparison, it is unclear whether or not this is a common physiological pattern in ants. As a parsimonious way to address this question, and, more generally, to increase the currently scant information available regarding the venom-producing capabilities of ants, the longevity, temporal polyethism, age-related venom production, and age-related venom replacement capabilities of workers of Jerdon's jumping ant, Harpegnathos saltator were investigated. Longevity varied from 10 days to nearly 2 years, with a median lifespan of 206 days. Workers remained in the nest when young, transitioned to outside work (foraging) after 50 days of age, and reached a plateau in their tendency to be outside the nest at 74 days of age. They eclosed with empty venom sacs, filled them by about 57 days of age, and were able to replace venom at all three ages tested (though at a higher rate when aged 100 days than 30 and 206). So, venom-production ability is not limited to early life in H. saltator workers, and aspects of venom physiology and exploratory behavior appear to coincide in a manner likely to result in foraging efficiency benefits; venom sacs reach fullness around the age workers begin their foraging careers, and venom replacement rate is highest around the age workers become the most dedicated foragers. PMID:23041374

Haight, Kevin L

2012-10-04

337

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

338

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

PubMed

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

2012-01-01

339

Spatial and temporal patterns in bacterial abundance, production and viral infection in a temporarily open/closed southern African estuary  

NASA Astrophysics Data System (ADS)

The spatial and temporal patterns in bacterial abundance, biomass, production, nanoflagellate abundance and the loss of bacterial production due to viral lysis were investigated in a temporarily open/closed estuary along the eastern seaboard of southern Africa over the period May 2006 to April 2007. Bacterial abundance, biomass and production ranged between 1.00 × 10 9 and 4.93 × 10 9 cells l -1, 32.43 and 108.59 ?g C l -1 and 0.01 and 1.99 ?g C l -1 h -1, respectively. With a few exceptions there were no significant spatial patterns in the values ( P > 0.05). Bacterial abundance, biomass and production, however, demonstrated a distinct temporal pattern with the lowest values consistently recorded during the winter months. Bacterial dynamics showed no effect of mouth opening events. Nanoflagellate and bacterial abundances were significantly correlated to one another ( P < 0.05) suggesting a strong predator-prey relationship. The frequency of visibly infected bacterial cells and the number of virus particles within each bacterial cell during the study demonstrated no significant temporal or spatial pattern ( P > 0.05) and ranged from 0.5 to 6.1% and 12.0 to 37.5 virus particles per bacterium, respectively. Viral infection and lysis was thus a constant source of bacterial mortality throughout the year. The estimated percentage of bacterial production removed by viral lysis ranged between 7.8 and 88.9% (mean = 30.3%) of the total which suggests that viral lysis represents a very important source of bacterial mortality during the study.

Allan, E. L.; Froneman, P. W.

2008-05-01

340

Temporal evolution and alternation of mechanisms of electric-field-induced patterns at ultralow-frequency driving.  

PubMed

The temporal evolution of patterns within the driving period of the ac voltage was studied in the 10-mHz-250-Hz frequency range. It was shown that the stationary electroconvection pattern of the conductive regime transforms into a flashing one at ultralow frequencies, existing only in narrow time windows within the period. Furthermore a transition between electroconvection and flexoelectric domains was detected which is repeating in each half period. The two patterns are well separated in time and in Fourier space. Simultaneous current measurements uncovered that the electric properties of the polyimide orienting layers influence the redistribution of the applied voltage. The experimental findings are in good qualitative agreement with the theoretical predictions based on an extended standard model including flexoelectricity. PMID:23005775

Éber, Nándor; Palomares, Laura O; Salamon, Péter; Krekhov, Alexei; Buka, Ágnes

2012-08-14

341

Dynamic maps: a visual-analytic methodology for exploring spatio-temporal disease patterns  

PubMed Central

Background Epidemiologic studies are often confounded by the human and environmental interactions that are complex and dynamic spatio-temporal processes. Hence, it is difficult to discover nuances in the data and generate pertinent hypotheses. Dynamic mapping, a method to simultaneously visualize temporal and spatial information, was introduced to elucidate such complexities. A conceptual framework for dynamic mapping regarding principles and implementation methods was proposed. Methods The spatio-temporal dynamics of Salmonella infections for 2002 in the U.S. elderly were depicted via dynamic mapping. Hospitalization records were obtained from the Centers of Medicare and Medicaid Services. To visualize the spatial relationship, hospitalization rates were computed and superimposed onto maps of environmental exposure factors including livestock densities and ambient temperatures. To visualize the temporal relationship, the resultant maps were composed into a movie. Results The dynamic maps revealed that the Salmonella infections peaked at specific spatio-temporal loci: more clusters were observed in the summer months and higher density of such clusters in the South. The peaks were reached when the average temperatures were greater than 83.4°F (28.6°C). Although the relationship of salmonellosis rates and occurrence of temperature anomalies was non-uniform, a strong synchronization was found between high broiler chicken sales and dense clusters of cases in the summer. Conclusions Dynamic mapping is a practical visual-analytic technique for public health practitioners and has an outstanding potential in providing insights into spatio-temporal processes such as revealing outbreak origins, percolation and travelling waves of the diseases, peak timing of seasonal outbreaks, and persistence of disease clusters.

2009-01-01

342

Capturing Patterns of Spatial and Temporal Autocorrelation in Ordered Response Data, Using a Bayesian Approach: A Case Study of Land Use Changes in Austin, Texas  

Microsoft Academic Search

Many databases involve ordered discrete responses in a temporal and spatial context, including, for example, land development intensity levels, vehicle ownership, and pavement conditions. An appreciation of such behaviors requires rigorous statistical methods, recognizing spatial effects and dynamic processes. This study develops a dynamic spatial ordered probit (DSOP) model in order to capture patterns of spatial and temporal autocorrelation in

Xiaokun Wang

343

The function of the proneural genes achaete and scute in the spatio-temporal patterning of the adult labellar bristles of Drosophila melanogaster  

Microsoft Academic Search

The sensory precursors for labellar taste bristles develop from the labial disc in three distinct temporal waves occurring at 0 h, 8 h and 14 h of pupal development. In each temporal wave, transcripts for the achaete (ac) and scute (sc) genes are expressed in overlapping patterns in cells of the disc epithelium prior to the appearance of sensory mother

Krishanu Ray; Veronica Rodrigues

1994-01-01

344

Spatial and temporal patterns of water-extractable organic carbon (WEOC) of surface mineral soil in a cool temperate forest ecosystem  

Microsoft Academic Search

Water-extractable organic carbon (WEOC) drives the C and N cycles in forest ecosystems via microbial activity. However, few studies have considered both then spatial and temporal patterns of WEOC in forest soils. We investigated the spatial and temporal variation in WEOC along a topographic sequence in a cool temperate deciduous forest. The concentrations of WEOC, carbohydrates, total phenols, and other

Takuo Hishi; Muneto Hirobe; Ryunosuke Tateno; Hiroshi Takeda

2004-01-01

345

An investigation of acoustic beam patterns for the sonar localization problem using a beam based method.  

PubMed

Target localization can be accomplished through an ultrasonic sonar system equipped with an emitter and two receivers. Time of flight of the sonar echoes allows the calculation of the distance of the target. The orientation can be estimated from knowledge of the beam pattern of the receivers and the ratio, in the frequency domain, between the emitted and the received signals after compensation for distance effects and air absorption. The localization method is described and, as its performance strongly depends on the beam pattern, the search of the most appropriate sonar receiver in order to ensure the highest accuracy of target orientation estimations is developed in this paper. The structure designs considered are inspired by the ear shapes of some bat species. Parameters like flare rate, truncation angle, and tragus are considered in the design of the receiver structures. Simulations of the localization method allow us to state which combination of those parameters could provide the best real world implementation. Simulation results show the estimates of target orientations are, in the worst case, 2° with SNR?=?50?dB using the receiver structure chosen for a potential practical implementation of a sonar system. PMID:23742357

Guarato, Francesco; Windmill, James; Gachagan, Anthony; Harvey, Gerald

2013-06-01

346

Lifelong susceptibility to acoustic trauma: changing patterns of cochlear damage over the life span of the mouse.  

PubMed

Age-related differences in susceptibility to noise-induced threshold shift (NITS) were examined over the entire life span of the CBA/J mouse. Mice of varying ages were given a single 5-min exposure to a 124-dB octave-band (12-24 kHz) noise. Susceptibility began at 15-16 days postpartum and increased rapidly until approximately 20 days of age. During this phase, NITS (as measured by increased action potential threshold) was greatest at 16 kHz. Overall susceptibility was consistently high from 20 to 90 days. During this phase, NITS became most severe at 32 kHz. From 120 days until beyond the end of its actuarial life span (527 days), NITS no longer occurred at 2-16 kHz, but the 64-kHz response retained its susceptibility to acoustic trauma. Mice at 20 and 60 days of age showed the same pattern of decreasing susceptibility as the intensity of the noise exposure was reduced to 114 and 104 dB, indicating that the absence of a tightly restricted critical period is not peculiar to a particular sound pressure level. PMID:6615342

Henry, K R

1983-01-01

347

Spatial and temporal patterns of chronic wasting disease: fine-scale mapping of a wildlife epidemic in Wisconsin.  

PubMed

Emerging infectious diseases threaten wildlife populations and human health. Understanding the spatial distributions of these new diseases is important for disease management and policy makers; however, the data are complicated by heterogeneities across host classes, sampling variance, sampling biases, and the space-time epidemic process. Ignoring these issues can lead to false conclusions or obscure important patterns in the data, such as spatial variation in disease prevalence. Here, we applied hierarchical Bayesian disease mapping methods to account for risk factors and to estimate spatial and temporal patterns of infection by chronic wasting disease (CWD) in white-tailed deer (Odocoileus virginianus) of Wisconsin, U.S.A. We found significant heterogeneities for infection due to age, sex, and spatial location. Infection probability increased with age for all young deer, increased with age faster for young males, and then declined for some older animals, as expected from disease-associated mortality and age-related changes in infection risk. We found that disease prevalence was clustered in a central location, as expected under a simple spatial epidemic process where disease prevalence should increase with time and expand spatially. However, we could not detect any consistent temporal or spatiotemporal trends in CWD prevalence. Estimates of the temporal trend indicated that prevalence may have decreased or increased with nearly equal posterior probability, and the model without temporal or spatiotemporal effects was nearly equivalent to models with these effects based on deviance information criteria. For maximum interpretability of the role of location as a disease risk factor, we used the technique of direct standardization for prevalence mapping, which we develop and describe. These mapping results allow disease management actions to be employed with reference to the estimated spatial distribution of the disease and to those host classes most at risk. Future wildlife epidemiology studies should employ hierarchical Bayesian methods to smooth estimated quantities across space and time, account for heterogeneities, and then report disease rates based on an appropriate standardization. PMID:19688937

Osnas, Erik E; Heisey, Dennis M; Rolley, Robert E; Samuel, Michael D

2009-07-01

348

Dose response and temporal patterns of radiation-associated solid cancer risks.  

PubMed

Findings of the Life Span Study (LSS) cohort of atomic-bomb survivors are a primary source for quantitative risk estimates that underlie radiation protection. Because of the size and length of follow-up, the LSS provides considerable information on both the nature of the dose response and on how radiation-associated excess risks vary with age, age at exposure, sex, and other factors. Our current analyses extend the mortality follow-up by 7 y (through 1997) and add 8 y (through 1995) to the incidence follow-up. During the follow-up periods there have been a total of about 9,300 solid cancer deaths and almost 12,200 incident cases. As outlined in this presentation, while discussing issues related to the shape of the dose response and low dose risks in some detail, the new reports consider temporal patterns in greater detail than has been done previously. As we have reported, the LSS solid cancer dose response is well described by simple linear dose response over the 0 to 2 Sv range (with some leveling off at higher estimated doses). This remains the case with the extended follow-up. Although LSS is often referred to as a high dose study, about 75% of the 50,000 cohort members with doses in excess of 5 mSv have dose estimates in a range of direct interest for radiation protection (0-200 mSv). Analyses of data limited to this low dose range provide direct evidence of a significant solid cancer dose response with a risk per unit dose that is consistent with that seen for the full dose range. Previous LSS reports have focused on descriptions of the solid cancer excess risks in which the excess relative risk varies with age at exposure and sex. In addition to the age at exposure effects, our current analyses suggest excess relative risks also vary with age (at death or diagnosis). Excess relative risks are higher for those exposed earlier in life, with attained age-specific risks changing by about 20% per decade, but tend to decrease with increasing attained age, roughly in proportion to (1/attained-age)1.5, for any age at exposure. Despite the decreasing relative risk, excess rates have increased rapidly throughout the study period with some indication, especially for the incidence data, that attained-age-specific rates are higher for those exposed at younger ages. Simple comparisons of site-specific excess risks are used to illustrate how the interpretation of age-at-exposure effects on excess relative risks or excess rates is complicated by changes in baseline rates with birth cohort or time period. PMID:12852470

Preston, D L; Pierce, D A; Shimizu, Y; Ron, E; Mabuchi, K

2003-07-01

349

Temporal patterns of surface ozone levels in different habitats of the North Western Mediterranean basin  

Microsoft Academic Search

A systematic temporal analysis of surface ozone observations in four sites representative of the main types of habitats: coast, mountain, inland and urban in the North Western Mediterranean basin is presented here for the period between 1994 and 2001. Concentrations were relatively high, especially in the coastal site where the European human and plant protection thresholds were surpassed an average

Àngela Ribas; Josep Peñuelas

2004-01-01

350

An analysis of clinical seizure patterns and their localizing value in frontal and temporal lobe epilepsies  

Microsoft Academic Search

Summary The differentiation of frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE) is a clinical problem of major theoretical and practical importance. Current electroclinical classification is based on retrospective studies of highly selected patients. When applied to the presurgical evaluation of patients, it has poor specificity. The current study adopts a different and prospective approach to the analysis of

M. Manford; D. R. Fish; S. D. Shorvon

1996-01-01

351

Habitat overlap of enemies: temporal patterns and the role of spatial complexity  

Microsoft Academic Search

Environmental heterogeneity can promote coexistence of conflicting species by providing spatial or temporal refuges from strong interactions (e.g., intraguild predation, competition). However, in many systems, refuge availability and effectiveness may change through time and space because of variability in habitat use by either species. Here I consider how the intensity of intraguild predation risk varies from day to night for

Stephanie E. Hampton

2004-01-01

352

TRACKING SPATIAL AND TEMPORAL COTTON DT PATTERNS WITH A NORMALIZED DIFFERENCE VEGETATION INDEX  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crop coefficients (Kc) are widely used to estimate crop evapotranspiration (ETc) for determining irrigation scheduling. Generalized Kc curves are limited to providing daily estimates of ETc for the 'typical' crop condition within a field. However, precision irrigation requires spatial and temporal E...

353

Temporal integration of sequential auditory events: silent period in sound pattern activates human planum temporale  

Microsoft Academic Search

Temporal integration is a fundamental process that the brain carries out to construct coherent percepts from serial sensory events. This process critically depends on the formation of memory traces reconciling past with present events and is particularly important in the auditory domain where sensory information is received both serially and in parallel. It has been suggested that buffers for transient

Henrietta Mustovic; Klaus Scheffler; Francesco Di Salle; Fabrizio Esposito; John G Neuhoff; Jürgen Hennig; Erich Seifritz

2003-01-01

354

SPATIAL-TEMPORAL PATTERN AND DRIVING FORCES OF LAND USE CHANGES IN XIAMEN  

Technology Transfer Automated Retrieval System (TEKTRAN)

Using the Landsat TM data of 1988, 1998 and 2001 respectively, this paper analyzes the spatial-temporal characteristics of land use changes during the 13 years from 1988 to 2001 in Xiamen, China. The purpose of the research is to analyze the dynamic process of land use and land cover changes in orde...

355

Spatial and Temporal Patterns in Stream Habitat and Smallmouth Bass Populations in Eastern Oklahoma  

Microsoft Academic Search

The spatial and temporal dynamics of stream habitat and fish populations are important considerations for the conservation and management of stream fishes. We determined how stream habitat and populations of smallmouth bass Micropterus dolomieu varied among third-order to fifth-order stream reaches in two regional streams in eastern Oklahoma from 2003 to 2005. Eastern Oklahoma represents the southwestern edge of the

Daniel C. Dauwalter; William L. Fisher

2008-01-01

356

Temporal patterns of happiness and information in a global social network: Hedonometrics and Twitter  

Microsoft Academic Search

Individual happiness is a fundamental societal metric. Normally measured through self-report, happiness has often been indirectly characterized and overshadowed by more readily quantifiable economic indicators such as gross domestic product. Here, we examine expressions made on the online, global microblog and social networking service Twitter, uncovering and explaining temporal variations in happiness and information levels over timescales ranging from hours

Peter Sheridan Dodds; Kameron Decker Harris; Isabel M. Kloumann; Catherine A. Bliss; Christopher M. Danforth

2011-01-01

357

Efficient Discrimination of Temporal Patterns by Motion-Sensitive Neurons in Primate Visual Cortex  

Microsoft Academic Search

the middle temporal (MT) cortex of alert monkeys en- code rapidly and unpredictably changing stimuli. We have adopted an approach in which encoding is defined in terms of the stimulus features that a neuron is best Summary able to discriminate rather than in terms of the features that drive it to fire fastest. We quantitate an average Although motion-sensitive neurons

Giedrius T. Burac; Anthony M. Zador; Michael R. DeWeese; Thomas D. Albright

2004-01-01

358

ECOLOGICAL BIOMECHANICS OF BENTHIC ORGANISMS: LIFE HISTORY, MECHANICAL DESIGN AND TEMPORAL PATTERNS OF MECHANICAL STRESS  

Microsoft Academic Search

We can gain biomechanical insights if we couple knowledge of the environments, ecological roles and life history strategies of organisms with our laboratory analyses of their mechanical function or fluid dynamics, as illustrated by studies of the mechanical design of bottom- dwelling marine organisms. Obviously, measurements of the spatial and temporal distribution of loads on an organism in nature reveal

M. A. R. KOEHL

1999-01-01

359

TEMPORAL GENE INDUCTION PATTERNS IN SHEEPSHEAD MINNOWS EXPOSED TO 17-ESTRADIOL  

EPA Science Inventory

Gene arrays provide a powerful method to examine changes in gene expression in fish due to chemical exposures in the environment. In this study, we expanded an existing gene array for sheepshead minnows (Cyprinodon variegatus) (SHM) and used it to examine temporal changes in gene...

360

Visual map development depends on the temporal pattern of binocular activity in mice  

Microsoft Academic Search

Binocular competition is thought to drive eye-specific segregation in the developing visual system, potentially through Hebbian synaptic learning rules that are sensitive to correlations in afferent activity. Altering retinal activity can disrupt eye-specific segregation, but little is known about the temporal features of binocular activity that modulate visual map development. We used optogenetic techniques to directly manipulate retinal activity in

Jiayi Zhang; James B Ackman; Hong-Ping Xu; Michael C Crair

2011-01-01

361

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 ...

362

Remote estimation of blood pulse pressure via temporal tracking of reflected secondary speckles pattern  

NASA Astrophysics Data System (ADS)

We present a novel technique for remote noncontact blood pulse pressure measurement. It is based on tracking both temporal and amplitude changes of reflected secondary speckle produced in human skin when illuminated by a laser beam. The implemented technique extracts the difference between the systolic and the diastolic blood pressure. Experimental results are presented showing good agreement when compared with conventional measurement methods.

Beiderman, Yevgeny; Horovitz, Israel; Burshtein, Natanel; Teicher, Mina; Garcia, Javier; Mico, Vicente; Zalevsky, Zeev

2010-11-01

363

Spatial and temporal patterns of soil erosion rates in an agricultural catchment, central Belgium  

Microsoft Academic Search

This paper presents results on the temporal and spatial variability of the erosional system in two adjacent cultivated catchments located in the Belgian Loam belt. Annual catchment erosion rates, calculated for the whole catchment area, range between 1 and 15 m3\\/ha · y. Mean annual catchment erosion rates calculated for a three year period, were 5.4 m3\\/ha · y and

Karel Vandaele; Jean Poesen

1995-01-01

364

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

365

Searching Electronic Health Records for Temporal Patterns in Patient Histories: A Case Study with Microsoft Amalga  

Microsoft Academic Search

As electronic health records (EHR) become more widespread, they enable clinicians and researchers to pose complex queries that can benefit immediate patient care and deepen understanding of medical treatment and outcomes. However, current query tools make complex temporal queries difficult to pose, and physicians have to rely on computer professionals to specify the queries for them. This paper describes our

Catherine Plaisant; Stanley Lam; Ben Shneiderman; Mark S. Smith; David Roseman; Greg Marchand; Michael Gillam; Craig Feied; Jonathan Handler; Hank Rappaport

366

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...

367

Identification of Damaged Wheat Kernels and Cracked-Shell Hazelnuts with Impact Acoustics Time-Frequency Patterns  

Technology Transfer Automated Retrieval System (TEKTRAN)

A new adaptive time-frequency (t-f) analysis and classification procedure is applied to impact acoustic signals for detecting hazelnuts with cracked shells and three types of damaged wheat kernels. Kernels were dropped onto a steel plate, and the resulting impact acoustic signals were recorded with ...

368

Temporal Patterns of Subjective Experiences and Self-Regulation during Ramadan Fasting among Elite Archers: A Qualitative Analysis  

PubMed Central

Purpose Some major competitions (e.g. London Olympics, 2012) are scheduled during the Ramadan fasting month. Little attention has been given to explore the archers’ performance related subjective experiences with a qualitative method. Therefore, this study addressed individual archers’ subjective experiences within the framework of self-regulation during Ramadan. Methods Eleven elite Malaysian Muslim fasting archers volunteered to participate in the study. Grounded theory was the qualitative approach used to examine the subjective experiences of athletes during Ramadan. Interviews were conducted and inductive content analysis was adopted to identify the temporal patterns of self-regulation of subjective experiences across the fasting period. Results Inductive content analysis identified (a) physical, (b) mental,(c) emotional, (d) behavioral, and (e) spiritual experiences. Overall patterns revealed that experiences associated with physical, emotional, behavioral, and spiritual dimensions dominated in the first phase of fasting, while the mental dimension surfaced increasingly in the latter phase of fasting. Conclusions The trend showed changes in the patterns of experiences among the major domains across the temporal dimension. Athletes reported increased subjective experiences in mental factors toward the latter half of the fasting period. Practitioners should emphasize on mental aspects of training, as these appear to be salient in archery performance.

Roy, Jolly; Hamidan, Shazarina; Singh, Rabindarjeet

2011-01-01

369

Multi-voxel pattern analysis of selective representation of visual working memory in ventral temporal and occipital regions.  

PubMed

While previous results from univariate analysis showed that the activity level of the parahippocampal gyrus (PHG) but not the fusiform gyrus (FG) reflects selective maintenance of the cued picture category, present results from multi-voxel pattern analysis (MVPA) showed that the spatial response patterns of both regions can be used to differentiate the selected picture category in working memory. The ventral temporal and occipital areas including the PHG and FG have been shown to be specialized in perceiving and processing different kinds of visual information, though their role in the representation of visual working memory remains unclear. To test whether the PHG and FG show spatial response patterns that reflect selective maintenance of task-relevant visual working memory in comparison with other posterior association regions, we reanalyzed data from a previous fMRI study of visual working memory with a cue inserted during the delay period of a delayed recognition task. Classification of FG and PHG activation patterns for the selected category (face or scene) during the cue phase was well above chance using classifiers trained with fMRI data from the cue or probe phase. Classification of activity in other temporal and occipital regions for the cued picture category during the cue phase was relatively less consistent even though classification of their activity during the probe recognition was comparable with the FG and PHG. In sum, these findings suggest that the FG and PHG carry information relevant to the cued visual category, and their spatial activation patterns during selective maintenance seem to match those during visual recognition. PMID:23380167

Han, Xufeng; Berg, Alexander C; Oh, Hwamee; Samaras, Dimitris; Leung, Hoi-Chung

2013-02-04

370

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

371

Temporal Motifs  

NASA Astrophysics Data System (ADS)

We discuss the temporal motifs approach that is aimed at detecting significant, intrinsically dynamic, mesoscopic structures and patterns in temporal networks, which cannot be seen in static or aggregated networks. Such patterns involve several nodes and their timed contacts. The approach consists of three phases: (1) identifying temporal subgraphs, (2) assigning the subgraphs to equivalence classes, and (3) assessing the relevance, surprise and significance of class-wise counts against some reference. We discuss these phases in detail, and apply the presented method to a temporal network of mobile telephone calls.

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

372

Mining Cluster-Based Temporal Mobile Sequential Patterns in Location-Based Service Environments  

Microsoft Academic Search

Researches on Location-Based Service (LBS) have been emerging in recent years due to a wide range of potential applications. One of the active topics is the mining and prediction of mobile movements and associated transactions. Most of existing studies focus on discovering mobile patterns from the whole logs. However, this kind of patterns may not be precise enough for predictions

Eric Hsueh-Chan Lu; Vincent S. Tseng; Philip S. Yu

2011-01-01

373

Complex temporal and spatial patterns in nonequilibrium processes. Progress report, December 1, 1987--November 30, 1992  

SciTech Connect

We have used dynamical systems methods to study and characterize bifurcations and pattern formation in a variety of nonequilibrium systems. In this paper we describe our work on dynamical systems, chemical oscillations and chaos, chemical spatial patterns, instabilities in fluid dynamics, electrodeposition clusters, the ballast resistor, and crack propagation.

Swinney, H.L.

1992-10-01

374

Temporal and spatial pattern of plastid gene expression during crucifer seedling development and embryogenesis  

Microsoft Academic Search

Several genes which are located close together on mustard (Sinapis alba L.) chloroplast DNA have been found to differ in their temporal mode of expression throughout seedling development. One predominant\\u000a expression program, exemplified by thepsbA gene, is characterized by an early (light-independent) rise in transcript levels, followed by subsequent further accumulation\\u000a to levels which are much higher in the light

C. Fiebig; H. Neuhaus; J. Teichert; W. Röcher; J. Degenhardt; G. Link

1990-01-01

375

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

376

Efficient Discrimination of Temporal Patterns by Motion-Sensitive Neurons in Primate Visual Cortex  

Microsoft Academic Search

Although motion-sensitive neurons in macaque middle temporal (MT) area are conventionally characterized using stimuli whose velocity remains constant for 1–3 s, many ecologically relevant stimuli change on a shorter time scale (30–300 ms). We compared neuronal responses to conventional (constant-velocity) and time-varying stimuli in alert primates. The responses to both stimulus ensembles were well described as rate-modulated Poisson processes but

Anthony M. Zador; Michael R. DeWeese; Thomas D. Albright

1998-01-01

377

Modeling Spatial and Temporal House Price Patterns: A Comparison of Four Models  

Microsoft Academic Search

This research reports results from a competition on modeling spatial and temporal components of house prices. A large, well-documented database was prepared and made available to anyone wishing to join the competition. To prevent data snooping, out-of-sample observations were withheld; they were deposited with one individual who did not enter the competition, but had the responsibility of calculating out-of-sample statistics

Bradford Case; John Clapp; Robin Dubin; Mauricio Rodriguez

2004-01-01

378

Spatial and temporal patterns of soil respiration over the Japanese Archipelago: a model intercomparison study  

Microsoft Academic Search

We used terrestrial ecosystem models to estimate spatial and temporal variability in and uncertainty of estimated soil carbon\\u000a dioxide (CO2) efflux, or soil respiration, over the Japanese Archipelago. We compared five carbon-cycle models to assess inter-model variability:\\u000a Biome-BGC, CASA, LPJ, SEIB, and VISIT. These models differ in approaches to soil carbon dynamics, root respiration estimation,\\u000a and relationships between decomposition and

Akihiko Ito; Kazuhito Ichii; Tomomichi Kato

2010-01-01

379

Stimulus features underlying reduced tremor suppression with temporally patterned deep brain stimulation  

PubMed Central

Deep brain stimulation (DBS) provides dramatic tremor relief when delivered at high-stimulation frequencies (more than ?100 Hz), but its mechanisms of action are not well-understood. Previous studies indicate that high-frequency stimulation is less effective when the stimulation train is temporally irregular. The purpose of this study was to determine the specific characteristics of temporally irregular stimulus trains that reduce their effectiveness: long pauses, bursts, or irregularity per se. We isolated these characteristics in stimulus trains and conducted intraoperative measurements of postural tremor in eight volunteers. Tremor varied significantly across stimulus conditions (P < 0.015), and stimulus trains with pauses were significantly less effective than stimulus trains without (P < 0.002). There were no significant differences in tremor between trains with or without bursts or between trains that were irregular or periodic. Thus the decreased effectiveness of temporally irregular DBS trains is due to long pauses in the stimulus trains, not the degree of temporal irregularity alone. We also conducted computer simulations of neuronal responses to the experimental stimulus trains using a biophysical model of the thalamic network. Trains that suppressed tremor in volunteers also suppressed fluctuations in thalamic transmembrane potential at the frequency associated with cerebellar burst-driver inputs. Clinical and computational findings indicate that DBS suppresses tremor by masking burst-driver inputs to the thalamus and that pauses in stimulation prevent such masking. Although stimulation of other anatomic targets may provide tremor suppression, we propose that the most relevant neuronal targets for effective tremor suppression are the afferent cerebellar fibers that terminate in the thalamus.

Birdno, Merrill J.; Kuncel, Alexis M.; Dorval, Alan D.; Turner, Dennis A.; Gross, Robert E.

2012-01-01

380

Hexagonal and roll flow patterns in temporally modulated Rayleigh-Bénard convection  

NASA Astrophysics Data System (ADS)

We present experimental results for pattern formation in a thin fluid layer heated time periodically from below. They were obtained with computer-enhanced shadowgraph flow visualization and with heat-flux measurements. The experimental cell was cylindrical, with a radius-to-height ratio of 11.0. The temperature of the top plate was held constant while that of the bottom plate was modulated sinusoidally so that the reduced Rayleigh number ???T/?Tc-1 had the form ?(t)=?0+? sin(?t). Here the time t and frequency ? are scaled by the vertical thermal diffusion time. Experiments were performed within the ranges 8.0<=?<=18.0, 0.4<=?<=3.3, and -0.2<=?0<=0.6. Measurements of the convective threshold shift ?c(?,?) were in good agreement with theoretical predictions. Comparisons were made with theoretical predictions of a range ?A(?,?)<=?0~?c) where only a hexagonal pattern with downflow at the cell centers is predicted to be stable, a range ?R<=?0patterns are expected to be stable, and a range ?0>=?B where only a roll pattern should be stable. low modulation amplitudes (?<~1.2 for ?=15) only rolls were observed over the range of ?0 studied, although the rolls appeared perturbed for ?A<=?0pattern with local sixfold symmetry and downflow at the cell centers, which was reproducible from one cycle to the next, was observed over the range ?A<~?0<~?R. Over the range ?0>~?B roll-like patterns were observed. Over the range ?R<~?0<~?B, where theory predicts bistability of rolls and hexagons, a coexistence between the two patterns was found. At high values of ? (?>~2.3 for ?=15), a pattern consisting of randomly placed cells and short roll segments that was reproducible from one cycle to the next was observed in all three regions. At still higher values of ? (?>3.0 for ?=13), this pattern was observed to be irreproducible from one cycle to the next. The transition from patterns resembling those predicted by the deterministic theory to irreproducible random patterns as ? is increased is presumed to be due to stochastic perturbations. These perturbations appear to play an important role in those parameter ranges where the amplitude of the pattern decays to a microscopic value during part of the modulation cycle.

Meyer, Christopher W.; Cannell, David S.; Ahlers, Guenter

1992-06-01

381

Spatial and temporal patterns of the mean annual precipitation at decadal time scale in southern Italy (Calabria region)  

NASA Astrophysics Data System (ADS)

Mean annual precipitation variability at decadal time scale over a southern Italy area (Calabria) was investigated to quantify the spatial and temporal patterns. A multivariate approach has been applied to analyse spatial-temporal (1921-2000) data of annual precipitation. A nested isotropic linear model of coregionalization was fitted to the experimental variograms including three basic structures: a nugget effect, an exponential model and a spherical model. The correlation structure between the decades was analysed by applying principal component analysis at each spatial scale, and specific factors at each characteristic scale were cokriged and mapped. Two components were identified: the first is mainly linked to local factors, which could be identified by the orographic characteristics of the region, while the long range component could be related to large-scale factors, like for example the processes of the global atmospheric circulation. In addition, in order to obtain a better insight into the pattern of relatively dry or wet zones, a standardized relative difference was calculated. The results showed that the annual precipitation decreased during the period 1921-2000 and the spatial distribution changed with an increase of dry areas.

Buttafuoco, Gabriele; Caloiero, Tommaso; Coscarelli, Roberto

2011-10-01

382

Species differences in the temporal pattern of Drosophila urate oxidase gene expression are attributed to trans-acting regulatory changes.  

PubMed Central

The Drosophila melanogaster urate oxidase (UO)-encoding gene is expressed in the third-instar larva and adult. In contrast, the Drosophila pseudoobscura UO gene is only expressed in the adult, whereas the Drosophila virilis UO gene is expressed only in the third-instar larva. UO activity in these three Drosophila species is detected exclusively within the Malpighian tubules. By using P-element mediated germ-line transformation, UO genes from D. pseudoobscura and D. virilis were integrated into the D. melanogaster genome. The D. virilis and D. pseudoobscura UO transgenes were expressed in the third-instar larva and adult Malpighian tubules, which is the D. melanogaster temporal pattern of UO gene expression. These observations indicate that differences in the temporal patterns of regulation of UO genes among these three Drosophila species are not likely to be due to evolutionary changes in the sequence or complement of UO cis-acting regulatory elements. The species differences in UO regulation are probably the result of changes in one or more trans-acting factors required for UO gene expression in the third-instar larval and adult stages. Images

Wallrath, L L; Friedman, T B

1991-01-01

383

Determining of spatial distribution patterns and temporal trends of an air pollutant using proper orthogonal decomposition basis functions  

NASA Astrophysics Data System (ADS)

This study aims to determine spatial patterns of an air pollutant dispersion and its temporal trends using proper orthogonal decomposition (POD) basis functions. The POD method is a model reduction technique for complex nonlinear problems and POD basis functions contain essential dynamics and physics of original problem. In the present work, the POD basis functions are applied to identify the dominant modes of carbon monoxide (CO) concentration in ambient air. For this purpose, CO concentration data for 15 monitoring stations over mega city of Tehran for 1339 days (1 Jan. 2006 to 31 Aug. 2009) are used. Data of monitoring stations are interpolated to generate 100 × 100 grid point network. Generated grid based data for all days create a time series of data that is the basic for constructing the POD basis functions. POD basis functions are obtained using eigenvectors of correlation matrix that is obtained using correlation of time series of data. The few number of the POD basis functions corresponding to the few first largest eigenvalues of correlation matrix are dominant modes. The results indicate that the first 7 largest eigenvalues of correlation matrix are 99 percent of the first 100 largest eigenvalues. This indicates that the first 7 POD basis functions out of 1339 capture the essential physics of CO distribution over region. Distribution of the first POD basis function over the city shows that the central and west-central parts of the city are more affected by CO pollutant. In addition, using the recorded data and the POD basis functions the temporal variation of each POD basis function is obtained. Results for the temporal variations of the POD basis functions show that the largest temporal trend belongs to the first POD basis function.

Ashrafi, Khosro

2012-02-01

384

Proceedings of NATO advanced research workshop on spatio-temporal patterns in nonequilibrium complex systems  

NASA Astrophysics Data System (ADS)

This workshop brought together experimentalists working with pattern forming systems in complex materials, such as liquid crystals, polymers, and biological systems, and theorists knowledgeable and interested in a physical understanding of the many, sometimes startlingly beautiful, patterns exhibited by these complex materials. Pattern formation in complex systems is important because it stimulates the growth of new physics and therefore new technologies. The technological relevance touched on at the workshop ranged from laser design, the development of high strength alloys, polymer processing, flat panel liquid crystal displays, and living systems. Just as descriptions in terms of order parameters revolutionized the understanding of phase transitions, the hope is that descriptions via amplitude equations and phase dynamics will give rise to simple descriptions of pattern formation in a wide variety of complex systems.

Simmons, L. M.

1995-05-01

385

A parametric investigation of pattern separation processes in the medial temporal lobe.  

PubMed

The hippocampus is thought to be involved in memory formation and consolidation, with computational models proposing the process of pattern separation as a means for encoding overlapping memories. Previous research has used semantically related targets and lures to investigate hippocampal responses to mnemonic interference. Here, we attempted to define the response function of the human hippocampus and its inputs during pattern separation by parametrically varying target-lure similarity in a continuous recognition task. We also investigated the effect of task demands (intentional vs incidental encoding) on pattern separation processes. We collected functional magnetic resonance imaging data while participants were shown a series of objects. In the intentional paradigm, participants identified objects as "new" (novel stimuli), "old" (exact repetitions), or "rotated" (previously seen objects that were subsequently rotated by varied degrees). In the incidental paradigm, participants were shown the same stimuli but identified objects as "toy" or "not toy." Activation in the hippocampus was best fit with a power function, consistent with predictions made by computational models of pattern separation processes in the hippocampus. The degree of pattern separation was driven by the information most relevant to the task: pattern separation was seen in the left hippocampus when semantic information was more important to the task and seen in the right hippocampus when spatial information was more important. We also present data illustrating that top-down processes modulate activity in the ventral visual processing stream. PMID:22993425

Motley, Sarah E; Kirwan, C Brock

2012-09-19

386

Acoustic interference in bush crickets; a factor in the evolution of singing insects?  

Microsoft Academic Search

This paper examines forms of acoustic interference in some European bush crickets, in particular the phenomenon of song modification, that occurs when individuals of different species sing together. This can result in inhibition of song, changes in the species-specific temporal pattern of the song, or, if the singers simply chorus in unison, songs may be masked. One of the principal

William Latimer; W. B. Broughton

1984-01-01

387

Spatio-temporal patterns of historical shallow landslides in a volcanic area, Mt. Aso, Japan  

NASA Astrophysics Data System (ADS)

The evaluation of spatially and temporally distributed records of translational shallow landslides in heterogeneous watersheds provides insights needed to understand disastrous processes. Recurrent slope instability events occurred between 1953 and 1998 in two watersheds of Mt. Aso, western Japan. This paper investigates (1) the spatio-temporal characteristics of translational shallow landslides (dimensions, numbers, densities, and area subjected to failure) observed at a particular location, (2) DEM based landform characteristics (elevation, slope angles, curvatures and their control on landslide distribution), and (3) rainfall characteristics. The evaluation of the landslide history, consequences and characteristics of spatially and temporally distributed landslides are based on the series of inventory maps for years 1954, 1977, 1990 and 1998. Geologically, the watersheds consist of pyroxene olivine andesite basalt lava, pyroclastics deposits, gravel, sand and clay deposits originated from Takadake, Nekodake, and Washigamine volcanoes. During 45 years (1953 1998), a total of 619 and 976 numbers of shallow landslides have been recognized in the Sakurakigawa and Furuegawa watersheds, respectively. Repeated sliding denuded a total surface area of 0.372 km2 in the Sakurakigawa watershed representing 35% of the watershed area. Similarly slides denuded a total of 0.534 km2 in the Furuegawa watershed representing 12% of the watershed area. For example, storm events of June 1953 and July 1990 with rainfall intensities of 49 and 61 mm h- 1, respectively triggered numerous landslides. About 25% and 47% of Sakurakigawa and Furuegawa watersheds, respectively still bears the potential to produce landslides. Landslides were commonly observed where thick unconsolidated tephra layers and pyroclastics rocks overlain by thin tephra bed existed, and for a slope inclination range of 30 35°.

Paudel, Prem P.; Omura, H.; Kubota, T.; Inoue, T.

2007-07-01

388

Patterns, predictors, variations, and temporal trends in emergency medical service hospital prenotification for acute ischemic stroke.  

PubMed

BACKGROUND#ENTITYSTARTX02014;: 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#ENTITYSTARTX02014;: 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#ENTITYSTARTX02014;: 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

2012-08-24

389

A self-organizing neural network architecture for auditory and speech perception with applications to acoustic and other temporal prediction problems  

Microsoft Academic Search

This project is developing autonomous neural network models for the real-time perception and production of acoustic and speech signals. Our SPINET pitch model was developed to take realtime acoustic input and to simulate the key pitch data. SPINET was embedded into a model for auditory scene analysis, or how the auditory system separates sound sources in environments with multiple sources.

Michael Cohen; Stephen Grossberg

1994-01-01

390

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 spatio-temporal variability of streamflow droughts in the Iberian Peninsula from 1945 to 2005. Streamflow series (187) homogeneously distributed across the study area were used to develop a streamflow index (the 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 to greater drought severity in the majority of regions. Drought duration, magnitude and spatial coverage was found to depend mainly on the 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.

2012-07-01

391

Defining temporal spatial patterns of mega city Istanbul to see the impacts of increasing population.  

PubMed

Rapid land use change has taken place over the last few decades in Istanbul. As most of the metropolitan areas, Istanbul faces increasing problems connected to increasing population and urbanisation. In this study, temporal changes of Istanbul's land use/cover were defined using remotely sensed data and post classification change detection method. For the aim of the study, relevant information was derived from different dated Landsat Thematic Mapper (TM) satellite data by using Unsupervised Iterative Self-Organizing Data Analysis Technique (ISODATA) and results were examined with matrix analysis method. Ground truth data were used for the classification and accuracy assessment of the classification. Temporal changes of land use/cover classes of the mega city Istanbul between the years of 1992, 1997 and 2005 were examined for the management and decision making process. Landsat TM images were classified into six land use/cover types: forest-green area, bare land, water surface, road, urban area, and mining area. The results show that urban areas and road categories are increased greatly by 13,630 and 5,018ha, respectively, but forest-green areas decreased by 77,722ha over 13years between 1992 and 2005. The reason for the decrease in green areas is mainly because of development of unplanned urbanization and unavoidable migration. PMID:18157736

Sanli, Fusun Balik; Balcik, Filiz Bektas; Goksel, Cigdem

2007-12-22

392

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

PubMed Central

Background The physiological mechanism by which bulls stimulate resumption of ovarian cycling activity in postpartum, anovular, suckled cows after calving may involve the concurrent activation of the hypothalamic-hypophyseal-ovarian (HPO) axis and hypothalamic-hypophyseal-adrenal (HPA) axis. Thus, the objectives of this experiment were to determine if characteristics of temporal patterns of cortisol and luteinizing hormone (LH) in postpartum, anovular, beef cows are influenced by acute exposure to bulls. The null hypotheses were that daily, temporal characteristics of cortisol and LH concentration patterns do not differ between cows exposed acutely to bulls or steers. Methods Sixteen cows were assigned randomly 67 +/- 4 (+/- SE) after calving to be exposed to bulls (EB, n = 8) or steers (ES, n = 8) 5 h daily for 9 d (D 0 to 8). Blood samples were collected daily from each cow via jugular catheters at 15-min intervals for 6 h from 1000 to 1600 h each day. The 5-h exposure period began 1 h after the start of the intensive bleeding period. Characteristics of cortisol and LH concentration patterns (mean, baseline, pulse frequency, pulse amplitude, and pulse duration) were identified by PULSAR analyses. Results Mean cortisol concentrations decreased (P < 0.05) in cows in both treatments from D 0 to D 2. Thereafter, mean cortisol concentrations stabilized and did not differ (P > 0.10) between EB and ES cows. The decrease in mean cortisol concentrations in EB and ES cows from D 0 to D 2 was attributed to cows acclimatizing to intensive blood sampling and handling procedures. Consequently, analyses for characteristics of cortisol and LH concentration patterns included D 2 through 8 only. Cortisol mean and baseline concentrations, and pulse amplitude did not differ (P > 0.10) between EB and ES cows. However, cortisol pulse duration tended to be longer (P = 0.09) and pulse frequency was lower (P = 0.05) in EB than ES cows. LH pulse frequency was greater (P = 0.06) in EB than ES cows. All other characteristics of LH concentration patterns did not differ (P > 0.10) between EB and ES cows. Characteristics of cortisol concentration patterns were not related to characteristics of LH concentration patterns for ES cows (P > 0.10). However, as cortisol pulse amplitude increased, LH pulse amplitude decreased (b1 = -0.04; P < 0.05) for EB cows. Conclusions In conclusion, exposing primiparous, postpartum, anovular, suckled cows to bulls for 5-h daily over a 9-d period did not alter mean concentrations of cortisol or LH compared to mean concentrations of cortisol and LH in cows exposed to steers. However, exposing cows to bull in this manner altered characteristics of temporal patterns of both LH and cortisol by increasing LH pulse frequency and decreasing cortisol pulse frequency. Interestingly, in cows exposed to bulls, as amplitude and frequency of cortisol pulses decreased, amplitudes of LH pulses increased and frequency of LH pulses tended to increase. Thus, the physiological mechanism of the biostimulatory effect of bulls may initially involve modification of the HPA axis and these changes may facilitate activation of the HPO axis and resumption of ovulatory cycles in postpartum, anovular, suckled cows.

2010-01-01

393

Spatio-temporal patterns of neuronal activity: analysis of optical imaging data using geometric shape matching.  

PubMed

Optical imaging of neuronal network activity yields information of spatial dynamics which generally is analyzed visually. The transient appearance of spatial activity patterns is difficult to gauge in a quantifiable manner, or may even altogether escape detection. Here, we employ geometric shape matching using Fréchet distances or straight skeletons to search for pre-selected patterns in optical imaging data with adjustable degrees of tolerance. Data were sampled from fluorescence changes of a voltage-sensitive dye recorded with a 464-photodiode array. Fluorescence was monitored in a neuronal network in vitro. Neuronal activity prompting fluorescence fluctuations consisted of spontaneous epileptiform discharges in neocortical slices from patients undergoing epilepsy surgery. The experiments show that: (a) spatial activity patterns can be detected in optical imaging data; (b) shapes such as "mini-foci" appear in close correlation to bioelectric discharges monitored with field potential electrodes in a reproducible manner; (c) Fréchet distances yield more conservative matches regarding rectangular, and less conservative hits with respect to radially symmetric shapes than the straight skeleton approach; and (d) tolerances of 0.03-0.1 are suited to detect faithful images of pre-selected shapes, whereas values >0.8 will report matches with any polygonal pattern. In conclusion, the methods reported here are suited to detect and analyze spatial, geometric dynamics in optical imaging data. PMID:11850035

Köhling, R; Reinel, J; Vahrenhold, J; Hinrichs, K; Speckmann, E-J

2002-02-15

394

Temporal pattern of the stress hormone and cytokine response in pigs following a lipopolysaccharide (LPS) challenge  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study assessed the pattern of immune and stress response following a LPS challenge. Crossbred pigs (n=28 pigs, 2 males and 2 females from 7 litters) were obtained at weaning (21 to 28 d of age). Pigs were transferred to a climate controlled facility, placed into individual pens and allowed ad l...

395

Predicting spatial and temporal patterns of soil temperature based on topography, surface cover and air temperature  

Microsoft Academic Search

Soil temperature is a variable that links surface structure to soil processes and yet its spatial prediction across landscapes with variable surface structure is poorly understood. In this study, a hybrid soil temperature model was developed to predict daily spatial patterns of soil temperature in a forested landscape by incorporating the effects of topography, canopy and ground litter. The model

S. Kang; S. Kim; S. Oh; D. Lee

2000-01-01

396

Temporal and spatial settlement patterns of sympatric hermit crabs and the influence of shell resource availability  

Microsoft Academic Search

Larvae of marine organisms often need specific resources or environments at settlement, and their success at settlement might be strongly influenced by the abundance and distribution of such specific resources. The larvae of hermit crabs need small shells to settle, so it is thought that the distribution and abundance of small shells influence the settlement pattern of hermit crabs. To

Takashi Oba; Seiji Goshima

2004-01-01

397

Temporal patterns in species flowering in Sky Islands of the Sonoran ...  

Treesearch

Jul 21, 2013 ... USA.gov Government Made Easy ... The flowering patterns of plants of the Finger Rock trail, located in the Santa Catalina Mountains of southern Arizona, have been very carefully ... We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.

398

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

399

Temporal and spatial expression patterns of the LEAFY homologue NLF during florogenesis in Narcissus tazetta  

Microsoft Academic Search

Studies of flower development in numerous plants suggest that the LEAFY gene (LFY) of Arabidopsis and its homologues in other species act as integrators of floral inductive signals and determine the fate of meristems. In Narcissus tazetta, the LFY homologue NLF was identified, and its expression pattern during flower development was studied under various temperature conditions. In N. tazetta, flower

Tal Noy-Porat; Rina Kamenetsky; Amram Eshel; Moshe A. Flaishman

2010-01-01

400

I. Spatio-temporal patterns of soil microbial and enzymatic activities in an agricultural soil  

Microsoft Academic Search

In the general context of the search of a quality index for soil as an indicator of sustainable management, we analyzed a soil recently subjected to agriculture from the “El Salado” river basin (Buenos Aires, Argentina) under no-till or conventional tillage (CT). We sought to detect whether a pattern of interactions among microbial, biochemical and physico-chemical variables in soil exists

M. A Aon; M. N Cabello; D. E Sarena; A. C Colaneri; M. G Franco; J. L Burgos; S Cortassa

2001-01-01

401

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

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil water patterns vary significantly due to precipitation, soil properties, topographic features, and land use. We used empirical orthogonal function (EOF) analysis to characterize the spatial variability of soil water across a 37-ha field of the Washington State University Cook Agronomy Farm near...

402

Spatio-temporal distribution patterns of the invasive macroalga Sargassum muticum within a Danish Sargassum -bed  

Microsoft Academic Search

Sargassum muticum was first observed in Scandinavia in Limfjorden (Denmark) in 1984, where it is now the most abundant and conspicuous macroalga.\\u000a Despite the ecological importance of Sargassum, few studies have described seasonal patterns within Scandinavian Sargassum beds. We quantified the dynamics of macroalgae among years and seasons along a depth transect through a typical Sargassum bed in Limfjorden. The

Mads S. Thomsen; Thomas Wernberg; Peter A. Stæhr; Morten F. Pedersen

2006-01-01

403

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 sensitivit