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1

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

E-print Network

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

Bohn, Kirsten

2

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

PubMed Central

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

Hofmann, Hilmar; Peeters, Frank

2013-01-01

3

Variability of spike trains and the processing of temporal patterns of acoustic signals—problems, constraints, and solutions  

Microsoft Academic Search

Object recognition and classification by sensory pathways is rooted in spike trains provided by sensory neurons. Nervous systems had to evolve mechanisms to extract information about relevant object properties, and to separate these from spurious features. In this review, problems caused by spike train variability and counterstrategies are exemplified for the processing of acoustic signals in orthopteran insects. Due to

B. Ronacher; A. Franz; S. Wohlgemuth; R. M. Hennig

2004-01-01

4

Representations of specific acoustic patterns in the auditory cortex and hippocampus  

PubMed Central

Previous behavioural studies have shown that repeated presentation of a randomly chosen acoustic pattern leads to the unsupervised learning of some of its specific acoustic features. The objective of our study was to determine the neural substrate for the representation of freshly learnt acoustic patterns. Subjects first performed a behavioural task that resulted in the incidental learning of three different noise-like acoustic patterns. During subsequent high-resolution functional magnetic resonance imaging scanning, subjects were then exposed again to these three learnt patterns and to others that had not been learned. Multi-voxel pattern analysis was used to test if the learnt acoustic patterns could be ‘decoded’ from the patterns of activity in the auditory cortex and medial temporal lobe. We found that activity in planum temporale and the hippocampus reliably distinguished between the learnt acoustic patterns. Our results demonstrate that these structures are involved in the neural representation of specific acoustic patterns after they have been learnt. PMID:25100695

Kumar, Sukhbinder; Bonnici, Heidi M.; Teki, Sundeep; Agus, Trevor R.; Pressnitzer, Daniel; Maguire, Eleanor A.; Griffiths, Timothy D.

2014-01-01

5

Temporal pattern processing in songbirds.  

PubMed

Understanding how the brain perceives, organizes and uses patterned information is directly related to the neurobiology of language. Given the present limitations, such knowledge at the scale of neurons, neural circuits and neural populations can only come from non-human models, focusing on shared capacities that are relevant to language processing. Here we review recent advances in the behavioral and neural basis of temporal pattern processing of natural auditory communication signals in songbirds, focusing on European starlings. We suggest a general inhibitory circuit for contextual modulation that can act to control sensory representations based on patterning rules. PMID:25201176

Comins, Jordan A; Gentner, Timothy Q

2014-10-01

6

Writing magnetic patterns with surface acoustic waves  

SciTech Connect

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

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

2014-05-07

7

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

8

Discovering Phonetic Coherence in Acoustic Patterns*  

E-print Network

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

9

Mining Sequential Patterns from Temporal Streaming Data  

E-print Network

Mining Sequential Patterns from Temporal Streaming Data A. Marascu and F. Masseglia INRIA Sophia.Marascu,Florent.Masseglia}@sophia.inria.fr Abstract. In recent years, emerging applications introduced new con- straints for data mining methods of our knowledge, no method has been proposed for mining sequential patterns in data streams. We argue

Malerba, Donato

10

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

PubMed Central

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

Vignal, Clémentine; Kelley, Darcy

2006-01-01

11

Mining Temporal Patterns for Humanoid Robot Using Pattern Growth Method  

Microsoft Academic Search

In this paper, we have projected an efficient mining method for a temporal dataset of humanoid robot HOAP-2 (Humanoid Open\\u000a Architecture Platform). This method is adequate to discover knowledge of intermediate patterns which are hidden inside different\\u000a existing patterns of motion of HOAP-2 joints. Pattern-growth method such as FP (Frequent Pattern) growth, unfolds many unpredictable\\u000a associations among different joint trajectories

Upasna Singh; Kevindra Pal Singh; G. C. Nandi

2009-01-01

12

Auditory Temporal Pattern Discrimination and Reading Ability  

ERIC Educational Resources Information Center

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

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

2004-01-01

13

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

PubMed Central

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

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

2015-01-01

14

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

PubMed

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

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

2015-01-01

15

Habitat-associated and temporal patterns of bat activity in a diverse forest landscape of southern New England, USA  

Microsoft Academic Search

The development and use of acoustic recording technology, surveys have revealed the composition, relative levels of activity,\\u000a and preliminary habitat use of bat communities of various forest locations. However, detailed examinations of acoustic surveys\\u000a results to investigate temporal patterns of bat activity are rare. Initial active acoustic surveys of bat activity on the\\u000a Quabbin Reservoir watershed in central Massachusetts recorded

Robert T. Brooks

2009-01-01

16

Patterns of acoustic variation in Cicada barbara Stal (Hemiptera, Cicadoidea)  

E-print Network

Patterns of acoustic variation in Cicada barbara Sta°l (Hemiptera, Cicadoidea) from the Iberian of the calling song and of an amplitude modulated signal produced by males of Cicada barbara from North Africa usefulness of acoustic data in the discrimination of subspecies and populations. Sound recordings were

Seabra, Sofia G.

17

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

E-print Network

Significance of temporal and spectral acoustic cues for sexual recognition in Xenopus laevis Cle As in many anurans, males of the totally aquatic species, Xenopus laevis, advertise their sexual receptivity-sexual acoustic communication; frog; Xenopus laevis; playback experiments; temporal and spectral cues 1

Kelley, Darcy B.

18

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

E-print Network

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

Benoit-Bird, Kelly J.

19

Dynamic membrane structure induces temporal pattern formation.  

PubMed

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

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

2014-10-01

20

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

PubMed

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

Comins, Jordan A; Gentner, Timothy Q

2014-09-01

21

Scaling properties in temporal patterns of schizophrenia  

NASA Astrophysics Data System (ADS)

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

Dünki, R. M.; Ambühl, B.

1996-02-01

22

Coding of multisensory temporal patterns in human superior temporal sulcus  

PubMed Central

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

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

2012-01-01

23

Temporal Dietary Patterns Using Kernel k-Means Clustering  

PubMed Central

Chronic diseases, such as heart disease, diabetes, and obesity, have been linked with diet. Nutrient intake is also associated with diet. However, much of the research completed to elucidate these associations has not incorporated the concept of time. This paper introduces the concept of temporal dietary patterns and demonstrates a novel construct of 24-hour temporal dietary patterns for energy intake, present in a sample of the adult U.S. population 20 years and older (NHANES 1999–2004 dataset). An appropriate distance metric is proposed for comparing 24-hour diet records and is used with kernel k-means clustering to identify the temporal dietary patterns. PMID:25258745

Khanna, Nitin; Eicher-Miller, Heather A; Boushey, Carol J.; Gelfand, Saul B.; Delp, Edward J.

2012-01-01

24

Visualizing Temporal Patterns in Large Multivariate Data using Textual Pattern Matching  

E-print Network

climate modeling research that aims at under- standing long-term climate change and combustion researchVisualizing Temporal Patterns in Large Multivariate Data using Textual Pattern Matching Markus, IEEE Abstract-- Extracting and visualizing temporal patterns in large scientific data is an open

Tennessee, University of

25

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...

26

Discovering Temporal Features and Relations of Activity Patterns  

E-print Network

Discovering Temporal Features and Relations of Activity Patterns Ehsan Nazerfard, Parisa Rashidi features and relations, has been largely ignored. One of the few works in this area by Rashidi and Cook [5

Cook, Diane J.

27

Tunable Nanowire Patterning Using Standing Surface Acoustic Waves  

PubMed Central

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

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

2014-01-01

28

Dynamic perfusion patterns in temporal lobe epilepsy  

Microsoft Academic Search

Purpose  To investigate dynamic ictal perfusion changes during temporal lobe epilepsy (TLE).\\u000a \\u000a \\u000a \\u000a Methods  We investigated 37 patients with TLE by ictal and interictal SPECT. All ictal injections were performed within 60 s of seizure\\u000a onset. Statistical parametric mapping was used to analyse brain perfusion changes and temporal relationships with injection\\u000a time and seizure duration as covariates.\\u000a \\u000a \\u000a \\u000a Results  The analysis revealed significant ictal hyperperfusion in

Patrick Dupont; John J. Zaknun; Alex Maes; Supatporn Tepmongkol; Silvia Vasquez; C. S. Bal; Wim Van Paesschen; Silvina Carpintiero; Chaichon Locharernkul; Maurizio Dondi

2009-01-01

29

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

30

Learning of timing patterns and the development of temporal expectations.  

PubMed

The present study investigated the learning of a culturally unfamiliar musical rhythm, leading to the development of temporal expectations, and it explored the potential for generalization across tempi and tasks. With that aim, we adapted the serial reaction time task to examine the learning of temporal structures by an indirect method. The temporal pattern employed was based on a complex interval ratio (2:3) and compared to one based on a simple interval ratio (1:2). In the exposure phase, non-musician participants performed a two-choice speeded discrimination task that required responding by key press to each event of the simple or complex auditory pattern. Participants were not informed about the temporal regularities; their task solely concerned the discrimination task. During exposure (Experiments 1-3), response times decreased over time for both temporal patterns, but particularly for the events following the longer interval of the more complex 2:3 pattern. Exposure further influenced performance in subsequent testing phases, notably the precision of tap timing in a production task (Experiment 2) and temporal expectations in a perception task (Experiment 3). Our findings promote the new paradigm introduced here as a method to investigate the learning of temporal structures. PMID:20683612

Tillmann, Barbara; Stevens, Catherine; Keller, Peter E

2011-05-01

31

Spatial and temporal patterns in conterminous United States streamflow characteristics  

NASA Astrophysics Data System (ADS)

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

McCabe, Gregory J.; Wolock, David M.

2014-10-01

32

SPECIAL ISSUE PATTERNS & PHENOTYPES Temporal and Spatial Expression of FGF  

E-print Network

in situ hybridisation at key developmental stages. It reveals the diverse expression pattern of fgf genesSPECIAL ISSUE PATTERNS & PHENOTYPES Temporal and Spatial Expression of FGF Ligands and Receptors During Xenopus Development Robert Lea, Nancy Papalopulu, Enrique Amaya,* and Karel Dorey* Fibroblast

Amaya, Enrique

33

Generalization in Learning Multiple Temporal Patterns Using RNNPB  

E-print Network

Generalization in Learning Multiple Temporal Patterns Using RNNPB Masato Ito1 and Jun Tani2 1 Sony of target patterns are self-organized during learning processes. An interesting characteristics of the RNNPB net architecture used in the current study. xt p ct xt+1 target trajectory ct+1 xt+1 ^ Fig. 1. The RNN

Tani, Jun

34

Sequential temporo-fronto-temporal activation during monitoring of the auditory environment for temporal patterns.  

PubMed

Subjects detected rarely occurring shifts between two simple tone-patterns, in a paradigm that dissociated the effects of rarity from those of pitch, habituation, and attention. Whole-head magnetoencephalography suggested that rare attended pattern-shifts evoked activity first in the superior temporal plane (sTp, peak ~100 ms), then superior temporal sulcus (sTs, peak ~130 ms), then posteroventral prefrontal (pvpF, peak ~230 ms), and anterior temporal cortices (aT, peak ~370 ms). Activity was more prominent in the right hemisphere. After subtracting the effects of nonshift tones (balanced for pitch and habituation status), weak but consistent differential effects of pattern-shifts began in aT at 90-130 ms, spread to sTs and sTp at ?130 ms, then pvpF, and finally returned to aT. Cingulate activity resembled prefrontal. Responses to pattern shifts were greatly attenuated when the same stimuli were ignored, suggesting that the initial superior temporal activity reflected an attention-related mismatch negativity. The prefrontal activity at ~230 ms corresponded in latency and task correlates with simultaneously recorded event-related potential components N2b and P3a; the subsequent temporal activity corresponded to the P3b. These results were confirmed in sensors specific for frontal or temporal cortex, and thus are independent of the inverse method used. Overall, these results suggest that auditory working memory for temporal patterns begins with detection of the pattern change by an interaction of anterior and superior temporal structures, followed by identification of the event and its consequences led by posteroventral prefrontal and cingulate cortices, and finally, definitive encoding of the event in anterior temporal areas. PMID:20665718

Halgren, Eric; Sherfey, Jason; Irimia, Andrei; Dale, Anders M; Marinkovic, Ksenija

2011-08-01

35

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

PubMed Central

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

2014-01-01

36

Vehicle Speed Estimation using Acoustic Wave Patterns Volkan Cevher, Member, IEEE, Rama Chellappa, Fellow, IEEE  

E-print Network

1 Vehicle Speed Estimation using Acoustic Wave Patterns Volkan Cevher, Member, IEEE, Rama Chellappa, Fellow, IEEE James H. McClellan, Fellow, IEEE Abstract-- We estimate a vehicle's speed, its wheelbase acoustic sensor that records the vehicle's drive-by noise. The acoustic wave pattern is determined using

Cevher, Volkan

37

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. PMID:22661942

Gansel, Kai S.; Singer, Wolf

2012-01-01

38

Finding Spatio-Temporal Patterns in Earth Science Data  

Microsoft Academic Search

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

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

2001-01-01

39

1988 Wet deposition temporal and spatial patterns in North America  

SciTech Connect

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

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

1992-03-01

40

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

41

Spatial and Temporal Patterns of Soil Frost in the  

E-print Network

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

Cherkauer, Keith

42

Spatial and Temporal Patterns of Chloride Deposition in Southern Sweden  

Microsoft Academic Search

Monthly bulk deposition of chloride at 49 stations in Southern Sweden between 1989 and 1995 was used to produce quarterly and annual deposition maps through ordinary block kriging. Generally, deposition decreases from the west coast and eastward and displays a large annual variation, governed by the frequency and intensity of midlatitude cyclones. The 1st quarter dominates the temporal pattern all

Mats E. R. Gustafsson; Eva Hallgren Larsson

2000-01-01

43

Spatio-Temporal Patterns for a Generalized Innovation Diffusion Model  

E-print Network

Spatio-Temporal Patterns for a Generalized Innovation Diffusion Model Fariba Hashemi Ecole and Mobility Laboratory (Transp-OR) August 31, 2010 Abstract We construct a model of innovation diffusion;Keywords: Diffusion of innovation - Bass' model - interactive multi- agent systems - local interactions

Bierlaire, Michel

44

Spatial and temporal patterns in conterminous United States streamflow characteristics  

NASA Astrophysics Data System (ADS)

Spatial and temporal patterns in annual and seasonal minimum, mean, and maximum daily streamflow values were examined for a set of 516 reference streamgages located throughout the conterminous United States for the period 1950 to 2010. First, cluster analysis was used to classify the streamgages into eight groups according to similarity in their temporal patterns. Standardized departure values (z-scores) of the flow metrics then were computed for each region and the associations between the annual metrics and well-known climate indices (NINO3.4, PDO, PNA, AMO, NAO) were determined. The results indicated that the temporal patterns in flow metrics (1) have strong spatial coherence within each region; (2) vary significantly among the regions; (3) are similar among the three annual flow metrics and the four seasonal flow metrics within each region; and (4) are only weakly associated with the tested climate indices. We conclude that most of the temporal variability in flow is unpredictable in terms of relations to climate indices and infer that future changes in flow characteristics cannot be predicted by these indices.

Wolock, D.; McCabe, G. J.

2012-12-01

45

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

PubMed Central

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

Leong, Victoria; Goswami, Usha

2014-01-01

46

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

E-print Network

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

47

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

Microsoft Academic Search

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

Jian-Da Wu; Chao-Qin Chuang

2005-01-01

48

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

E-print Network

LETTER Biodiversity, productivity and the temporal stability of productivity: patterns. Additionally, we tested whether biodiversity, productivity and temporal stability were similarly influenced that favoured unproductive species increased both biodiversity and temporal stability. Species interactions

Wilsey, Brian J.

49

Network-based comparison of temporal gene expression patterns  

PubMed Central

Motivation: In the pursuits of mechanistic understanding of cell differentiation, it is often necessary to compare multiple differentiation processes triggered by different external stimuli and internal perturbations. Available methods for comparing temporal gene expression patterns are limited to a gene-by-gene approach, which ignores co-expression information and thus is sensitive to measurement noise. Methods: We present a method for co-expression network based comparison of temporal expression patterns (NACEP). NACEP compares the temporal patterns of a gene between two experimental conditions, taking into consideration all of the possible co-expression modules that this gene may participate in. The NACEP program is available at http://biocomp.bioen.uiuc.edu/nacep. Results: We applied NACEP to analyze retinoid acid (RA)-induced differentiation of embryonic stem (ES) cells. The analysis suggests that RA may facilitate neural differentiation by inducing the shh and insulin receptor pathways. NACEP was also applied to compare the temporal responses of seven RNA inhibition (RNAi) experiments. As proof of concept, we demonstrate that the difference in the temporal responses to RNAi treatments can be used to derive interaction relationships of transcription factors (TFs), and therefore infer regulatory modules within a transcription network. In particular, the analysis suggested a novel regulatory relationship between two pluripotency regulators, Esrrb and Tbx3, which was supported by in vivo binding of Esrrb to the promoter of Tbx3. Availability: The NACEP program and the supplementary documents are available at http://biocomp.bioen.uiuc.edu/nacep. Contact: szhong@illinois.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:20889495

Huang, Wei; Cao, Xiaoyi; Zhong, Sheng

2010-01-01

50

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

51

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

E-print Network

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

Pierce, Graham

52

Acceleration of ultrasound thermal therapy by patterned acoustic droplet vaporization  

PubMed Central

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

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

2014-01-01

53

Acceleration of ultrasound thermal therapy by patterned acoustic droplet vaporization.  

PubMed

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

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

2014-01-01

54

Acoustically induced strong interaction between two periodically patterned elastic plates  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

55

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

PubMed

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

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

2013-07-01

56

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

PubMed Central

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

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

2013-01-01

57

Management and research applications of real-time and archival passive acoustic sensors over varying temporal and spatial scales  

Microsoft Academic Search

Defining the appropriate scale over which to conduct a study in the marine environment is critical to achieving appropriate scientific, management, mitigation and conservation objectives. This paper focuses on applications of passive acoustic technologies over a range of spatial and temporal scales. It is divided into sections dealing with archival and real-time passive acoustic sensor applications. Each section assesses the

Sofie M. Van Parijs; Chris W. Clark; Renata S. Sousa-Lima; Susan E. Parks; Shannon Rankin; Denise Risch; Ilse C. Van Opzeeland

2009-01-01

58

Temporal summation of global form signals in dynamic Glass patterns.  

PubMed

The ability to perceive complex objects in the environment requires that the visual system integrate local form information into global shapes. Glass patterns (GPs) are stimuli that are commonly used to study this integration process. GPs consist of randomly positioned dot-pairs oriented in a coherent way to create a global form. When multiple GPs are presented sequentially, observers report a percept of illusory coherent motion and have lower detection thresholds relative to a single presentation GPs. The percept of illusory motion has been attributed to the visual system interpreting the dot-pairs in GPs as motion streaks. However, it remains unclear why dynamic GPs are detected at lower thresholds than static GPs. Two main differences exist between static and dynamic GPs: (a) dynamic GPs contain multiple presentations of global form signals compared to a single presentation in static GPs and (b) dynamic GPs have a greater temporal frequency than static GPs. Here we investigated which of these two factors contributed to the heightened sensitivities for dynamic GPs. We systematically varied the number of unique GPs and the rate at which each unique frame is presented (i.e., temporal frequency). The results show that, within the range of temporal frequency used, the primary influence on detection thresholds was the number of unique frames. These results suggest that the improved detection sensitivities can be driven by a mechanism of temporal summation of global form. PMID:25451242

Nankoo, Jean-François; Madan, Christopher R; Spetch, Marcia L; Wylie, Douglas R

2015-02-01

59

Sophisticated Temporal Pattern Recognition in Retinal Ganglion Cells  

PubMed Central

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

Schwartz, Greg; Berry, Michael J.

2010-01-01

60

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

61

Reconstructing spatial and temporal patterns of paleoglaciation across Central Asia  

NASA Astrophysics Data System (ADS)

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

Stroeven, Arjen P.

2014-05-01

62

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

E-print Network

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

Kumar, Vipin

63

[Modulation of the functional activity of the acoustic and visual analyzers under conditions of listening to one's own EEG acoustic image of the temporal and occipital cortex areas].  

PubMed

Investigation into the functional activity of the acoustic and visual analyzer has been carried out before and after procedures of listening to one's own EEG of the temporal and occipital cortex areas. It has been shown, that there is a dependence of the dynamics of latent periods of sensomotor response to modality of stimuli and localization of source of the EEG acoustic image. After listening to acoustic image of the temporal EEG, a reduction of sensomotor reaction latency in the acoustic test has been observed. After listening to acoustic image of the occipital EEC, a reduction of sensomotor reaction latency in the visual test has been observed. In the control session after listening to A. Vivaldi's music, no significant shifts of sensomotor reaction latency have been observed. A conclusion has been made that, under conditions of local EEG-acoustic feedback, there is a selective elevation of functional activity of the brain areas used as the EEG-source for acoustic image forming. PMID:19323448

Konstantinov, K V; Trushina, V N; Iakovlev, N M; Klimenko, V M

2009-01-01

64

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

PubMed

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

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

2014-01-01

65

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

PubMed Central

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

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

2014-01-01

66

Measurement resolution of noise directivity patterns from acoustic flight tests  

NASA Technical Reports Server (NTRS)

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

Conner, David A.

1989-01-01

67

A Temporal Pattern Mining Approach for Classifying Electronic Health Record Data  

PubMed Central

We study the problem of learning classification models from complex multivariate temporal data encountered in electronic health record systems. The challenge is to define a good set of features that are able to represent well the temporal aspect of the data. Our method relies on temporal abstractions and temporal pattern mining to extract the classification features. Temporal pattern mining usually returns a large number of temporal patterns, most of which may be irrelevant to the classification task. To address this problem, we present the Minimal Predictive Temporal Patterns framework to generate a small set of predictive and non-spurious patterns. We apply our approach to the real-world clinical task of predicting patients who are at risk of developing heparin induced thrombocytopenia. The results demonstrate the benefit of our approach in efficiently learning accurate classifiers, which is a key step for developing intelligent clinical monitoring systems. PMID:25309815

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

2013-01-01

68

Temporal patterns of solar eclipses on areostationary relay satellites  

NASA Astrophysics Data System (ADS)

Mars Areostationary Relay Satellites are considered robust candidates to meet the telecommunications needs of the coming set of Mars science missions. Orbital station-keeping manoeuvres are required to compensate natural perturbations on the areostationary orbit. This paper deals on the pattern description of solar eclipses in the areostationary orbit to allow to test the constrain imposed by the impossibility to perform manoeuvres at the eclipse times. We present here the models used to characterize the two eclipse epochs around the spring and autumn equinoxes over a Martian year. In average, each eclipse season lasts 90 sols in eclipse with a daily maxima duration of about 1 h 18 min plus 2 min 54 s of penumbra. Temporal duration of solar eclipses with different values near to zero inclination and different satellite orbit nodes has been also analyzed.

Romero, P.; Antolín, R.

2014-09-01

69

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

PubMed

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

Krajewski, Jarek; Batliner, Anton; Golz, Martin

2009-08-01

70

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

71

Statistical methods for investigating quiescence and other temporal seismicity patterns  

USGS Publications Warehouse

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

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

1988-01-01

72

Niche Overlap and Temporal Activity Patterns of Social Wasps (Hymenoptera: Vespidae) in a Brazilian Cashew Orchard  

E-print Network

Niche Overlap and Temporal Activity Patterns of Social Wasps (Hymenoptera: Vespidae) in a Brazilian as a glucidic resource by wasps was quantified in an orchard to evaluate temporal overlap for a species-rich guild of social wasps and to determine if temporal partitioning within this guild reduces competition

Willig, Michael

73

Comparison of acoustic and net sampling systems to determine patterns in zooplankton distribution  

E-print Network

that are currently used to measure scattering from zooplankton vary in their design and operation, and some were originally manufactured for other purposes. Acoustic Doppler Current Profilers (ADCPs), primarily used and with predicted volume backscatter calculated from a coincident net tow. Spatially and temporally coincident data

Pierce, Stephen

74

Assessment of Spatial and Temporal Patterns of Log Structures in East Tennessee  

E-print Network

Reding Assessment of Spatial and Temporal Patterns of Log Structures in East Tennessee A Thesis Presentedfor the Master of Science Degree The University of Tennessee, Knoxville William M. May 2002 #12;Reding M. entitled"Assessment of Spatial and Temporal Patterns of Log Structures in East Tennessee." I have

Grissino-Mayer, Henri D.

75

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

76

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

PubMed Central

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

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

2013-01-01

77

Patterns of subregional mesiotemporal disease progression in temporal lobe epilepsy  

PubMed Central

Objective: Evidence for disease progression in the mesiotemporal lobe is mainly derived from global volumetry of the hippocampus. In this study, we tracked progressive structural changes in the hippocampus, amygdala, and entorhinal cortex in drug-resistant temporal lobe epilepsy at a subregional level. Furthermore, we evaluated the relation between disease progression and surgical outcome. Methods: We combined cross-sectional modeling of disease duration in a large cohort of patients (n = 134) and longitudinal analysis in a subset that delayed surgery (n = 31). To track subregional pathology, we applied surface-shape analysis techniques on manual mesiotemporal labels. Results: Longitudinal and cross-sectional designs showed consistent patterns of progressive atrophy in hippocampal CA1, anterolateral entorhinal, and the amygdalar laterobasal group bilaterally. These regions also exhibited more marked age-related volume loss in patients compared with controls. We found a faster progression of hippocampal atrophy in patients with a seizure frequency ?6 per month. High rates of contralateral entorhinal cortex atrophy predicted postsurgical seizure relapse. Conclusion: We observed progressive atrophy in hippocampal, amygdalar, and entorhinal subregions that frequently display neuronal loss on histology. The bilateral character of cumulative atrophy highlights the importance of early surgery. In patients who nevertheless delay this procedure, serial scanning may provide markers of surgical outcome. PMID:24142475

Bernhardt, Boris C.; Kim, Hosung

2013-01-01

78

Air pollution in Accra neighborhoods: spatial, socioeconomic, and temporal patterns.  

PubMed

This study examined the spatial, socioeconomic status (SES), and temporal patterns of ambient air pollution in Accra, Ghana. Over 22 months, integrated and continuous rooftop particulate matter (PM) monitors were placed at a total of 11 residential or roadside monitoring sites in four neighborhoods of varying SES and biomass fuel use. PM concentrations were highest in late December and January, due to dust blown from the Sahara. Excluding this period, annual PM(2.5) ranged from 39 to 53 microg/m(3) at roadside sites and 30 to 70 microg/m(3) at residential sites; mean annual PM(10) ranged from 80 to 108 microg/m(3) at roadside sites and 57 to 106 microg/m(3) at residential sites. The low-income and densely populated neighborhood of Jamestown/Ushertown had the single highest residential PM concentration. There was less difference across traffic sites. Daily PM increased at all sites at daybreak, followed by a mid-day peak at some sites, and a more spread-out evening peak at all sites. Average carbon monoxide concentrations at different sites and seasons ranged from 7 to 55 ppm, and were generally lower at residential sites than at traffic sites. The results show that PM in these four neighborhoods is substantially higher than the WHO Air Quality Guidelines and in some cases even higher than the WHO Interim Target 1, with the highest pollution in the poorest neighborhood. PMID:20205383

Dionisio, Kathie L; Arku, Raphael E; Hughes, Allison F; Vallarino, Jose; Carmichael, Heather; Spengler, John D; Agyei-Mensah, Samuel; Ezzati, Majid

2010-04-01

79

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

NASA Astrophysics Data System (ADS)

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

Yuan, Baoguo; Cheng, Ying; Liu, Xiaojun

2015-02-01

80

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

PubMed Central

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

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

2012-01-01

81

Detection of Acoustic Temporal Fine Structure by Cochlear Implant Listeners: Behavioral Results and Computational Modeling  

PubMed Central

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.

2013-01-01

82

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

2013-04-01

83

Spatial and Temporal Patterns of Aerosol-Cloud Interactions  

NASA Astrophysics Data System (ADS)

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

Fuchs, Julia; Cermak, Jan

2014-05-01

84

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, 4 backs and 5 forwards (age 25.1 ± 3.1 years) participated during 2 "Roma 7" international tournaments (2010 and 2011). All the players were at the professional level in the highest Italian rugby union, and 5 of these players also competed at the international level. During the matches (n = 15), the players were filmed to assess game performance. Global positioning system, heart rate (HR), and blood lactate (BLa) concentration data were measured and analyzed. The mean total distance covered throughout matches was 1,221 ± 118 m (first half = 643 ± 70 m and second half = 578 ± 77 m; with a decrease of 11.2%, p > 0.05, Effect Size [ES] = 0.29). The players achieved 88.3 ± 4.2 and 87.7 ± 3.4% of the HRmax during the first and second halves, respectively. The BLa for the first and second halves was 3.9 ± 0.9 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 the 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 M

2014-03-01

85

Cell patterning with a heptagon acoustic tweezer--application in neurite guidance.  

PubMed

Accurate control over positioning of cells is a highly desirable feature in tissue engineering applications since it allows, for example, population of substrates in a controlled fashion, rather than relying on random seeding. Current methods to achieve a differential distribution of cells mostly use passive patterning methods to change chemical, mechanical or topographic properties of surfaces, making areas differentially permissive to the adhesion of cells. However, these methods have no ad hoc control over the actual deposition of cells. Direct patterning methods like bioprinting offer good control over cell position, but require sophisticated instrumentation and are often cost- and time-intensive. Here, we present a novel electronically controlled method of generating dynamic cell patterns by acoustic trapping of cells at a user-determined position, with a heptagonal acoustic tweezer device. We demonstrate the capability of the device to create complex patterns of cells using the device's ability to re-position acoustic traps by using a phase shift in the acoustic wave, and by switching the configuration of active piezoelectric transducers. Furthermore, we show that by arranging Schwann cells from neonatal rats in a linear pattern we are able to create Bands of Büngner-like structures on a non-structured surface and demonstrate that these features are able to guide neurite outgrowth from neonatal rat dorsal root ganglia. PMID:24817215

Gesellchen, F; Bernassau, A L; Déjardin, T; Cumming, D R S; Riehle, M O

2014-07-01

86

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

PubMed

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

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

2013-11-01

87

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

PubMed Central

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

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

2013-01-01

88

Defining spatial and temporal patterns of phylogeographic structure in Madagascar's iguanid  

E-print Network

Defining spatial and temporal patterns of phylogeographic structure in Madagascar's iguanid lizards Department, University of Antananarivo, BP 906, Antananarivo 101, Madagascar, Association Vahatra, BP 3972, Antananarivo 101, Madagascar Abstract Understanding the remarkably high species diversity and levels

Yoder, Anne

89

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

E-print Network

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

Olson, Karen L.

90

Reconstruction of Missing Data in Social Networks Based on Temporal Patterns of Interactions  

E-print Network

in the series of interaction events between agents in a social network. We then develop a reconstruction modelReconstruction of Missing Data in Social Networks Based on Temporal Patterns of Interactions Alexey results to the Los Angeles gang network. Keywords: Social networks, temporal dependence of events, missing

Bertozzi, Andrea L.

91

ACOUSTIC IDENTIFICATION AND MEASUREMENT OF ACTIVITY PATTERNS OF WHITE GRUBS IN SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Activity patterns of Phyllophaga crinita (Burmeister), P. congrua (LeConte), P. crassissima (Blanchard), and Cyclocephala lurida (Bland) grubs were acoustically monitored in small pots of bluegrass, Poa arachnifera Torr, at varying and constant temperatures over multiple-day periods. Distinctive te...

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

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

E-print Network

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

Mahanta, Anjana K

2012-01-01

94

Acoustic cue selection and discrimination under degradation: Differential contributions of the inferior parietal and posterior temporal cortices.  

PubMed

Auditory categorization is a vital skill for perceiving the acoustic environment. Categorization depends on the discriminability of the sensory input as well as on the ability of the listener to adaptively make use of the relevant features of the sound. Previous studies on categorization have focused either on speech sounds when studying discriminability or on visual stimuli when assessing optimal cue utilization. Here, by contrast, we examined neural sensitivity to stimulus discriminability and optimal cue utilization when categorizing novel, non-speech auditory stimuli not affected by long-term familiarity. In a functional magnetic resonance imaging (fMRI) experiment, listeners categorized sounds from two category distributions, differing along two acoustic dimensions: spectral shape and duration. By introducing spectral degradation after the first half of the experiment, we manipulated both stimulus discriminability and the relative informativeness of acoustic cues. Degradation caused an overall decrease in discriminability based on spectral shape, and therefore enhanced the informativeness of duration. A relative increase in duration-cue utilization was accompanied by increased activity in left parietal cortex. Further, discriminability modulated right planum temporale activity to a higher degree when stimuli were spectrally degraded than when they were not. These findings provide support for separable contributions of parietal and posterior temporal areas to perceptual categorization. The parietal cortex seems to support the selective utilization of informative stimulus cues, while the posterior superior temporal cortex as a primarily auditory brain area supports discriminability particularly under acoustic degradation. PMID:25481793

Scharinger, Mathias; Henry, Molly J; Obleser, Jonas

2015-02-01

95

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

PubMed

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

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

2013-11-01

96

Spatial and temporal pattern analysis via spiking neurons  

Microsoft Academic Search

. Spiking neurons, receiving temporally encoded inputs, can compute radialbasis functions (RBFs) by storing the relevant information in their delays. In thispaper we show how these delays can be learned using exclusively locally availableinformation (basically the time difference between the pre- and postsynaptic spike).Our approach gives rise to a biologically plausible algorithm for finding clusters in ahigh dimensional input space

Thomas Natschläger; Berthold Ruf

1998-01-01

97

Crime Forecasting Using Spatio-Temporal Pattern with Ensemble Learning  

E-print Network

granularity levels. Crime distributions are of different sizes and shapes with respect to spatial space over with temporal, spatial, societal, and ecological factors. In an attempt to utilize all these factors in crime from local crime cluster distributions in different time periods at different granularity levels. We

Ding, Wei

98

Spatial and Temporal Patterns of Tidal Dissipation in Synchronous Satellites  

NASA Technical Reports Server (NTRS)

Tidal heating is an important energy source for several solar system bodies, and there is a wide-spread perception that the pattern of surface heat flow is diagnostic of internal structure. We wish to clarify that situation. Our analysis depends upon two important assumptions: First, that heat transport is dominated by conduction. Second, that the body can be modeled by a sequence of spherically symmetric layers, each with a linear visco-elastic rheology. Under these assumptions, surface heat flow patterns in tidally dominated satellites will reflect radially integrated dissipation patterns. For synchronously rotating satellites with zero obliquity, this pattern depends quite strongly on orbital eccentricity but relatively little on purely radial variations in internal structure. The total amount of heat generated within the body does depend sensitively on internal structure, but the spatial pattern is rather insensitive to structure, especially at low orbital eccentricities.

Bills, Bruce G.; Aharonson, Oded

2003-01-01

99

The role of contrasting temporal amplitude patterns in the perception of speech  

NASA Astrophysics Data System (ADS)

Despite a lack of traditional speech features, novel sentences restricted to a narrow spectral slit can retain nearly perfect intelligibility [R. M. Warren et al., Percept. Psychophys. 57, 175-182 (1995)]. The current study employed 514 listeners to elucidate the cues allowing this high intelligibility, and to examine generally the use of narrow-band temporal speech patterns. When 13-octave sentences were processed to preserve the overall temporal pattern of amplitude fluctuation, but eliminate contrasting amplitude patterns within the band, sentence intelligibility dropped from values near 100% to values near zero (experiment 1). However, when a 13-octave speech band was partitioned to create a contrasting pair of independently amplitude-modulated 16-octave patterns, some intelligibility was restored (experiment 2). An additional experiment (3) showed that temporal patterns can also be integrated across wide frequency separations, or across the two ears. Despite the linguistic content of single temporal patterns, open-set intelligibility does not occur. Instead, a contrast between at least two temporal patterns is required for the comprehension of novel sentences and their component words. These contrasting patterns can reside together within a narrow range of frequencies, or they can be integrated across frequencies or ears. This view of speech perception, in which across-frequency changes in energy are seen as systematic changes in the temporal fluctuation patterns at two or more fixed loci, is more in line with the physiological encoding of complex signals.

Healy, Eric W.; Warren, Richard M.

2003-03-01

100

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

NASA Technical Reports Server (NTRS)

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

Crist, E. P.

1982-01-01

101

Seasonal forcing drives spatio-temporal pattern formation in rabies epidemics  

E-print Network

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

102

113 Years of Physical Review: Using Flow Maps to Show Temporal and Topical Citation Patterns  

E-print Network

113 Years of Physical Review: Using Flow Maps to Show Temporal and Topical Citation Patterns Bruce time-topic reference system. The citations from 2005 papers are overlaid as flow maps from each topic to the papers referenced by papers in the topic making intercitation patterns between topic areas visible. Paper

Indiana University

103

Modeling spatio-temporal wildfire ignition point patterns  

Microsoft Academic Search

We analyze and model the structure of spatio-temporal wildfire ignitions in the St. Johns River Water Management District\\u000a in northeastern Florida. Previous studies, based on the K-function and an assumption of homogeneity, have shown that wildfire events occur in clusters. We revisit this analysis based\\u000a on an inhomogeneous K-function and argue that clustering is less important than initially thought. We

Amanda S. Hering; Cynthia L. Bell; Marc G. Genton

2009-01-01

104

Observation of spatio-temporal pattern in magnetised rf plasmas  

NASA Astrophysics Data System (ADS)

We address an experimental observation of pattern formation in a magnetised rf plasma. The experiments are carried out in a electrically grounded aluminium chamber which is housed inside a rotatable superconducting magnetic coil. The plasma is formed by applying a rf voltage in parallel plate electrodes in push-pull mode under the background of argon gas. The time evolution of plasma intensity shows that a homogeneous plasma breaks into several concentric radial spatiotemoral bright and dark rings. These rings propagate radially at considerably low pressure and a constant magnetic field. These patterns are observed to trap small dust particles/grains in their potential. Exploiting this property of the patterns, a novel technique to measure the electric field associated with the patterns is described. The resulting estimates of the corresponding field intensity are presented. At other specific discharge parameters the plasma shows a range of special type of characteristic structures observed in certain other chemical, mechanical and biological systems.

Bandyopadhyay, P.; Sharma, D.; Konopka, U.; Morfill, G.

2014-02-01

105

Effects of acoustic overstimulation on spectral and temporal processing in the amphibian auditory nerve.  

PubMed

Activity of isolated auditory-nerve fibers in tree frogs (Eleutherodactylus coqui) exposed to continuous 3-min tones of different intensities at their characteristic frequencies (CFs) was recorded. Period histograms show a retardation in the preferred phase of discharge during and after the cessation of the exposure. Postexposure phase shift is concomitant with an elevation in CF thresholds and related to the level of tone exposure above threshold. Vector strength does not show comparable trends of change; postexposure shifts are related to preexposure CF thresholds. Recovery of phase retardation is rapid; units exposed to successive 3-min tones of the same intensities with intervals of 10-14 min between exposures experienced similar changes in their patterns of temporal discharge. Micromechanical changes affecting stereocilia stiffness or structural alterations in the tectorial membrane of the amphibian papilla may underly the transitory phase shifts observed in traumatized anuran auditory fibers. PMID:2708678

Penna, M; Narins, P M

1989-04-01

106

Temporally diverse firing patterns in olfactory receptor neurons underlie spatiotemporal neural codes for odors  

PubMed Central

Odorants are represented as spatiotemporal patterns of spikes in neurons of the antennal lobe (AL, insects) and olfactory bulb (OB, vertebrates). These response patterns have been thought to arise primarily from interactions within the AL/OB, an idea supported, in part, by the assumption that olfactory receptor neurons (ORNs) respond to odorants with simple firing patterns. However, activating the AL directly with simple pulses of current evoked responses in AL neurons that were much less diverse, complex, and enduring than responses elicited by odorants. Similarly, models of the AL driven by simplistic inputs generated relatively simple output. How then are dynamic neural codes for odors generated? Consistent with recent results from several other species, our recordings from locust ORNs showed a great diversity of temporal structure. Further, we found that, viewed as a population, many response features of ORNs were remarkably similar to those observed within the AL. Using a set of computational models constrained by our electrophysiological recordings, we found that the temporal heterogeneity of responses of ORNs critically underlies the generation of spatiotemporal odor codes in the AL. A test then performed in vivo confirmed that, given temporally homogeneous input, the AL cannot create diverse spatiotemporal patterns on its own; however, given temporally heterogeneous input, the AL generated realistic firing patterns. Finally, given the temporally structured input provided by ORNs, we clarified several separate, additional contributions of the AL to olfactory information processing. Thus, our results demonstrate the origin and subsequent reformatting of spatiotemporal neural codes for odors. PMID:20147528

Raman, Baranidharan; Joseph, Joby; Tang, Jeff; Stopfer, Mark

2010-01-01

107

Avian Incubation Patterns Reflect Temporal Changes in Developing Clutches.  

PubMed

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

Cooper, Caren B; Voss, Margaret A

2013-01-01

108

Spatial hearing benefits demonstrated with presentation of acoustic temporal fine structure cues in bilateral cochlear implant listeners.  

PubMed

Most contemporary cochlear implant (CI) processing strategies discard acoustic temporal fine structure (TFS) information, and this may contribute to the observed deficits in bilateral CI listeners' ability to localize sounds when compared to normal hearing listeners. Additionally, for best speech envelope representation, most contemporary speech processing strategies use high-rate carriers (?900?Hz) that exceed the limit for interaural pulse timing to provide useful binaural information. Many bilateral CI listeners are sensitive to interaural time differences (ITDs) in low-rate (<300?Hz) constant-amplitude pulse trains. This study explored the trade-off between superior speech temporal envelope representation with high-rate carriers and binaural pulse timing sensitivity with low-rate carriers. The effects of carrier pulse rate and pulse timing on ITD discrimination, ITD lateralization, and speech recognition in quiet were examined in eight bilateral CI listeners. Stimuli consisted of speech tokens processed at different electrical stimulation rates, and pulse timings that either preserved or did not preserve acoustic TFS cues. Results showed that CI listeners were able to use low-rate pulse timing cues derived from acoustic TFS when presented redundantly on multiple electrodes for ITD discrimination and lateralization of speech stimuli. PMID:25190398

Churchill, Tyler H; Kan, Alan; Goupell, Matthew J; Litovsky, Ruth Y

2014-09-01

109

Ictal chronology and interictal spikes predict perfusion patterns in temporal lobe epilepsy: a multivariate study  

Microsoft Academic Search

Typical (TPP) and atypical (APP) perfusion patterns (PP) may be seen in ictal SPECT of patients with temporal lobe epilepsy (TLE). APP may pose problem in the lateralization of the epileptogenic zone (EZ). We aimed to investigate predictive variables for the occurrence of TPP and APP.Fifty-one TLE patients were submitted to successful anterior-mesial temporal lobectomy. Univariate (UVA) and multivariate (MVA)

Lauro Wichert-Ana; Tonicarlo Rodrigues Velasco; Vera Cristina Terra-Bustamante; Veriano Alexandre; Ricardo Guarnieri; Roger Walz; Mery Kato; Whemberton Martins Araújo; Carlos Gilberto Carlotti; David Araújo; Antonio Carlos Dos Santos; Américo Ceiki Sakamoto

2004-01-01

110

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

111

Different temporal patterns of vector soliton bunching induced by polarization-dependent saturable absorber  

NASA Astrophysics Data System (ADS)

A fiber laser with either a polarization-independent semiconductor saturable absorption mirror (PID-SESAM) or a polarization-dependent SESAM (PD-SESAM) as a passive mode-locker is constructed for obtaining the vector soliton bunching. The temporal patterns of the soliton bunching generated from the fiber laser with a PD-SESAM are much more abundant than that in fiber laser with a PID-SESAM. Only the vibrating soliton bunching is generated from the fiber laser with a PID-SESAM. However, there are another three interesting temporal patterns of the soliton bunching generated from the fiber laser with a PD-SESAM except for the vibrating soliton bunching. They are variable length soliton bunching, breathing soliton bunching and stable soliton bunching along the slow axis induced by polarization instability. It is found that the polarization property of the saturable absorber plays a pivotal role for achieving different temporal patterns of the soliton bunching.

Chen, Wei-Cheng; Chen, Guo-Jie; Han, Ding-An; Li, Bin

2014-06-01

112

Learning Temporal Patterns of Risk in a Predator-Diverse Environment  

PubMed Central

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

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

2012-01-01

113

Temporal evolution of pattern disparity processing in humans  

PubMed Central

Stereo matching, i.e., the matching by the visual system of corresponding parts of the images seen by the two eyes, is inherently a 2-D problem. To gain insights into how this operation is carried out by the visual system, we measured, in human subjects, the reflexive vergence eye movements elicited by the sudden presentation of stereo plaids. We found compelling evidence that the 2-D pattern disparity is computed by combining disparities first extracted within orientation selective channels. This neural computation takes 10–15 ms, and is carried out even when subjects perceive not a single plaid but rather two gratings in different depth planes (transparency). However, we found that 1-D disparities are not always effectively combined: When spatial frequency and contrast of the gratings are sufficiently different pattern disparity is not computed, a result that cannot be simply attributed to the transparency of such stimuli. Based on our results, we propose that a narrow-band implementation of the Intersection Of Constraints (IOC) rule (Fennema and Thompson, 1979; Adelson and Movshon, 1982), preceded by cross-orientation suppression, underlies the extraction of pattern disparity. PMID:23426674

Quaia, Christian; Sheliga, Boris M; Optican, Lance M; Cumming, Bruce G

2013-01-01

114

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

SciTech Connect

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

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

2006-12-15

115

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

116

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

117

Temporal patterns in seedling establishment on pocket gopher disturbances.  

PubMed

Disturbances often facilitate seedling establishment, and can change the species composition of a community by increasing recruitment of disturbance-adapted species. To understand the effects of pocket gopher disturbances on alpine seedling dynamics, we examined the gopher disturbances' effects on seedling emergence and survival on gopher disturbances 0 to 5 years old. In contrast to results from most other ecosystems, these recently created gopher mounds had lower seedling emergence and survival rates than undisturbed areas. A lack of correlation between species' abundances on gopher mounds and undisturbed sites in one of the two communities studied suggested that a suite of disturbance-adapted species recruited onto the mounds. To explain low seedling emergence on recent gopher mounds, we quantified gopher mound seed banks and studied recruitment in a site with mounds that ranged from 0 to >20 years old. Seed numbers in first-year gopher mound soils were extremely low relative to undisturbed soils, and this pattern was mirrored in seedling establishment patterns over the long term. Gopher disturbance depressed seedling emergence density for the first 5 years. Subsequently, emergence density increased until at least 20 years following the disturbance. Emergence on disturbances more than 20 years old was higher than on undisturbed sites. Therefore, gopher disturbances probably facilitate seedling establishment in alpine dry and moist meadow; however, this process takes place over decades. PMID:14557865

Forbis, Tara A; Larmore, Jason; Addis, Elizabeth

2004-01-01

118

Temporal patterns of tick-borne granulocytic anaplasmosis in California.  

PubMed

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

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

2011-06-01

119

Spatial and temporal emergence pattern of Lyme disease in Virginia.  

PubMed

The emergence of infectious diseases over the past several decades has highlighted the need to better understand epidemics and prepare for the spread of diseases into new areas. As these diseases expand their geographic range, cases are recorded at different geographic locations over time, making the analysis and prediction of this expansion complicated. In this study, we analyze spatial patterns of the disease using a statistical smoothing analysis based on areal (census tract level) count data of Lyme disease cases in Virginia from 1998 to 2011. We also use space and space-time scan statistics to reveal the presence of clusters in the spatial and spatiotemporal distribution of Lyme disease. Our results confirm and quantify the continued emergence of Lyme disease to the south and west in states along the eastern coast of the United States. The results also highlight areas where education and surveillance needs are highest. PMID:25331806

Li, Jie; Kolivras, Korine N; Hong, Yili; Duan, Yuanyuan; Seukep, Sara E; Prisley, Stephen P; Campbell, James B; Gaines, David N

2014-12-01

120

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

E-print Network

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

Grunwald, Sabine

121

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

PubMed Central

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

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

2011-01-01

122

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

PubMed

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

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

2011-01-01

123

Spatio-temporal patterns in pelvic reduction in threespine stickleback (Gasterosteus aculeatus L.)  

E-print Network

Spatio-temporal patterns in pelvic reduction in threespine stickleback (Gasterosteus aculeatus L Questions: The pelvic girdle with associated spines is an integrated anti-predator defence apparatus to produce the pelvic apparatus in ion-poor and mineral- challenging freshwater. Hypothesis: Stickleback

Bernatchez, Louis

124

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

E-print Network

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

125

Spatio-temporal patterns in obsidian consumption in the Southern Nasca Region, Peru  

E-print Network

Spatio-temporal patterns in obsidian consumption in the Southern Nasca Region, Peru Jelmer W Accepted 10 November 2009 Keywords: Obsidian Exchange Mobility Provenance analysis Nasca Peru a b s t r a c t Geochemical data from 426 obsidian artifacts collected from a range of sites in the Southern Nasca Region (SNR

126

ATTITUDES AND SOCIAL COGNITION The Temporal Pattern to the Experience of Regret  

E-print Network

ATTITUDES AND SOCIAL COGNITION The Temporal Pattern to the Experience of Regret Thomas Gilovich cause more pain in the short-term, but inactions are regretted more in the long run. Support and Tversky (1982a): Thomas Gilovich and Victoria Husted Medvec, Department of Psy- chology, Cornell

127

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

Microsoft Academic Search

BACKGROUND: With the objective of identifying spatial and temporal patterns of enzootic raccoon variant rabies, a spatial scan statistic was utilized to search for significant terrestrial rabies clusters by year in New York State in 1997–2003. Cluster analyses were unadjusted for other factors, adjusted for covariates, and adjusted for covariates and large scale geographic variation (LSGV). Adjustments were intended to

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

2007-01-01

128

Comparing Spatial and Temporal Patterns of Landslides and Rainfall, Using Remote Sensing  

Microsoft Academic Search

Although many non-climate factors contribute to slope instability, the intensity and duration of rainfall has been strongly linked to the initiation of shallow, rapidly moving landslides. Our primary focus is to characterize the spatial and temporal patterns of rainfall during an intense storm, using ground-based radar, for comparison with the distribution of associated landslides. Unlike rain gauges (which are sparsely

A. J. MacLeod; J. Roering; S. Yuter

2005-01-01

129

December 2004 509Notes TEMPORAL PATTERNS OF DDE IN BURROWING OWL EGGS FROM THE  

E-print Network

December 2004 509Notes TEMPORAL PATTERNS OF DDE IN BURROWING OWL EGGS FROM THE IMPERIAL VALLEY.gervais@usu.edu ABSTRACT We compared levels of DDE contamination in the eggs of burrowing owls (Athene cunicularia) from local de contaminante para esta poblacio´n residente de bu´hos. Burrowing owls (Athene cunicularia) fre

Gervais, Jennifer

130

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

ERIC Educational Resources Information Center

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

Morrongiello, Barbara A.

1984-01-01

131

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

E-print Network

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

Li, Linhua

2009-06-02

132

Temporal expression patterns of period in cryb and vg mutants of Drosophila melanogaster  

Microsoft Academic Search

In Drosophila melanogaster, the gene products of period (per) and timeless are essential components of the cir- cadian clock. The temporal expression patterns of per at various time points were studied in the intestine and salivary glands of wild type (WT), cryptochrome- absent (cry b ), and vestigial (vg) mutants under 12 : 12 h light : dark and 12

G. Suthakar; P. Subramanian; T. Manivasagam

133

ORIGINAL PAPER Temporal changes in the spatial pattern of leaf traits  

E-print Network

ORIGINAL PAPER Temporal changes in the spatial pattern of leaf traits in a Quercus robur population. Several leaf traits may show spatial structure at the same scale as light or soil resources. However the years than the non-limiting nutrient. We also hypothesized that single leaf traits [leaf N, leaf P

Paris-Sud XI, Université de

134

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

135

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

E-print Network

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

Robillard, Martin

136

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

E-print Network

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

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

2015-01-01

137

Temporal patterns of self-injurious behavior correlate with stress hormone levels in the developmentally disabled  

PubMed Central

While the origins and developmental course of self-injurious behavior (SIB) remain relatively unknown, recent studies suggest a biological imbalance may potentiate or provoke the contagious recurrence of SIB patterns in individuals with severe developmental disabilities (DD). Evidence from several laboratories indicates that functioning, relations, and processing of a stress-related molecule, proopiomelanocortin, (POMC), may be perturbed among certain subgroups of individuals exhibiting SIB. The current investigation employed a unique time-pattern analysis program (THEME) to examine whether recurrent temporal patterns (T-patterns) of SIB were related to morning levels of two POMC-derived hormones: ?-endorphin (?E) and adrenocorticotropic hormone (ACTH). THEME was used to quantify highly significant (nonrandom) T-patterns that included SIB within a dataset of in-situ observational recordings spanning 8 days (~40 hours) in 25 subjects with DD. Pearson’s product-moment analyses revealed highly significant correlations between the percentage of T-patterns containing SIB and basal levels of both ?E and ACTH, which were not found with any other “control” T-patterns. These findings support the hypothesis that the recurrent temporal patterning of SIB represents a unique behavioral phenotype directly related to perturbed levels of POMC-derived stress hormones in certain individuals with severe DD. PMID:17913241

Kemp, Aaron S.; Fillmore, Paul T.; Lenjavi, Mohammed R.; Lyon, Melvin; Chicz-DeMet, Aleksandra; Touchette, Paul E.; Sandman, Curt A.

2007-01-01

138

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

2007-07-01

139

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

140

Acoustics  

NASA Technical Reports Server (NTRS)

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

Goodman, Jerry R.; Grosveld, Ferdinand

2007-01-01

141

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

PubMed Central

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

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

2013-01-01

142

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

143

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

PubMed Central

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

Francis, Malcolm P.

2013-01-01

144

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

PubMed

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

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

2013-09-01

145

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

146

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

NASA Technical Reports Server (NTRS)

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

Hinton, Yolanda L.

1999-01-01

147

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

148

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

PubMed Central

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

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

2013-01-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

150

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

PubMed

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

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

2013-01-01

151

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

PubMed Central

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

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

2013-01-01

152

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

PubMed Central

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

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

2013-01-01

153

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

2013-01-01

154

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

Microsoft Academic Search

.   In this paper we examine spatio-temporal pattern formation in reaction-diffusion systems on the surface of the unit sphere\\u000a in 3D. We first generalise the usual linear stability analysis for a two-chemical system to this geometrical context. Noting\\u000a the limitations of this approach (in terms of rigorous prediction of spatially heterogeneous steady-states) leads us to develop,\\u000a as an alternative, a

M. A. J. Chaplain; M. Ganesh; I. G. Graham

2001-01-01

155

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. PMID:24046731

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

2013-01-01

156

Selection of spectro-temporal patterns in multichannel MEG with support vector machines for schizophrenia classification.  

PubMed

We present a new framework for the diagnosis of schizophrenia based on the spectro-temporal patterns selected by a support vector machine from multichannel magnetoencephalogram (MEG) recordings in a verbal working memory task. In the experimental paradigm, five letters appearing sequentially on a screen were memorized by subjects. The letters constituted a word in one condition and a pronounceable nonword in the other. Power changes were extracted as features in frequency subbands of 248 channel MEG data to form a rich feature dictionary. A support vector machine has been used to select a small subset of features with recursive feature elimination technique (SVM-RFE) and the reduced subset was used for classification. We note that the discrimination between patients and controls in the word condition was higher than in the non-word condition (91.8% vs 83.8%). Furthermore, in the word condition, the most discriminant patterns were extracted in delta (1-4 Hz), theta (4-8Hz) and alpha (12-16 Hz) frequency bands. We note that these features were located around the left frontal, left temporal and occipital areas, respectively. Our results indicate that the proposed approach can quantify discriminative neural patterns associated to a functional task in spatial, spectral and temporal domain. Moreover these features provide interpretable information to the medical expert about physiological basis of the illness and can be effectively used as a biometric marker to recognize schizophrenia in clinical practice. PMID:19163476

Ince, Nuri F; Goksu, Fikri; Pellizzer, Giuseppe; Tewfik, Ahmed; Stephane, Massoud

2008-01-01

157

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

PubMed

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

Matell, Matthew S

2014-01-01

158

Groundwater-Surface Water Interactions along a Lake Shore: Spatial Patterns and Temporal Dynamics  

NASA Astrophysics Data System (ADS)

In this study the spatial and temporal variability of groundwater-surface water interactions along a lake shore is investigated by combining different experimental methods. Study area is Lake Hinnensee, situated in the lake district north of Berlin in Germany. The lake is a seepage lake with no surface inflows or outflows. To investigate the spatial patterns of groundwater surface water interactions as well as their temporal dynamics we applied a number of different techniques: snapshots of spatial patterns were determined by gridded measurements of temperature profiles in the lake sediment as well as with distributed temperature sensing (DTS), using a fiber optic cable placed at the sediment surface. The spatial resolution of measurements adequate for pattern detection was determined by comparing experimental designs at various spatial scales and resolutions. Continuous time series of water levels and temperature time series in piezometer transects at different locations along the lake shore give insight into both spatial variability and temporal dynamics of vertical hydraulic gradients and heat transport. Exfiltration rates of groundwater into the lake were estimated with 3 different approaches. The experimental methodologies were evaluated in a "cost-benefit" analysis, comparing effort with scientific benefit. The results show that groundwater exfiltration into the lake is to some extent variable in time and is highly variable in space: there is a strong gradient perpendicular to the lake shore as well as high heterogeneity along the lake shore.

Blume, T.; Tecklenburg, C.; Krause, S.; Lewandowski, J.

2012-12-01

159

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

160

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

161

Finding motifs in birdsong data in the presence of acoustic noise and temporal jitter.  

PubMed

Here we present a novel approach to quickly and reliably find long (200 ms - 2 s) stereotyped sequences of sounds ("motifs") in acoustic recordings of birdsong. Robust and time-efficient identification of such sequences is a crucial first step in many studies ranging from development to neuronal basis of motor behavior. Accurately identifying motifs is usually hindered by the presence of animal-intrinsic variability in execution and tempo, and by extrinsic acoustic noise (e.g., movement artifacts, ambient noise). The algorithm we describe in this report has been optimized to work in bird species that sing stereotyped syllable sequences (such as the zebra finch), and requires minimal user involvement (? 5 min for over 1,000 motifs). Importantly, it is transparent and robust to the choice of parameters. PMID:24773442

Fantana, Antoniu L; Kozhevnikov, Alexay

2014-04-01

162

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

PubMed

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

Choo, Youngmin; Seong, Woojae; Song, Heechun

2014-09-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

165

Spatio-Temporal Patterns of Barmah Forest Virus Disease in Queensland, Australia  

PubMed Central

Background Barmah Forest virus (BFV) disease is a common and wide-spread mosquito-borne disease in Australia. This study investigated the spatio-temporal patterns of BFV disease in Queensland, Australia using geographical information system (GIS) tools and geostatistical analysis. Methods/Principal Findings We calculated the incidence rates and standardised incidence rates of BFV disease. Moran's I statistic was used to assess the spatial autocorrelation of BFV incidences. Spatial dynamics of BFV disease was examined using semi-variogram analysis. Interpolation techniques were applied to visualise and display the spatial distribution of BFV disease in statistical local areas (SLAs) throughout Queensland. Mapping of BFV disease by SLAs reveals the presence of substantial spatio-temporal variation over time. Statistically significant differences in BFV incidence rates were identified among age groups (?2?=?7587, df?=?7327,p<0.01). There was a significant positive spatial autocorrelation of BFV incidence for all four periods, with the Moran's I statistic ranging from 0.1506 to 0.2901 (p<0.01). Semi-variogram analysis and smoothed maps created from interpolation techniques indicate that the pattern of spatial autocorrelation was not homogeneous across the state. Conclusions/Significance This is the first study to examine spatial and temporal variation in the incidence rates of BFV disease across Queensland using GIS and geostatistics. The BFV transmission varied with age and gender, which may be due to exposure rates or behavioural risk factors. There are differences in the spatio-temporal patterns of BFV disease which may be related to local socio-ecological and environmental factors. These research findings may have implications in the BFV disease control and prevention programs in Queensland. PMID:22022430

Naish, Suchithra; Hu, Wenbiao; Mengersen, Kerrie; Tong, Shilu

2011-01-01

166

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

167

Detection of Anoplophora glabripennis (Coleoptera: Cerambycidae) larvae in different host trees and tissues by automated analyses of sound-impulse frequency and temporal patterns.  

PubMed

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), an invasive pest quarantined in the United States, is difficult to detect because the larvae feed unseen inside trees. Acoustic technology has potential for reducing costs and hazards of tree inspection, but development of practical methods for acoustic detection requires the solution of technical problems involving transmission of resonant frequencies in wood and high background noise levels in the urban environments where most infestations have occurred. A study was conducted to characterize sounds from larvae of different ages in cambium, sapwood, and heartwood of bolts from three host tree species. Larval sounds in all of the tested trees and tissues consisted primarily of trains of brief, 3-10-ms impulses. There were no major differences in the spectral or temporal pattern characteristics of signals produced by larvae of different ages in each tissue, but larval sounds in sapwood often had fewer spectral peaks than sounds in cambium and heartwood. A large fraction, but not all background sounds could be discriminated from larval sounds by automated spectral analyses. In 3-min recordings from infested bolts, trains containing impulses in patterns called bursts occurred frequently, featuring 7-49 impulses separated by small intervals. Bursts were rarely detected in uninfested bolts. The occurrence of bursts was found to predict infestations more accurately than previously used automated spectral analyses alone. Bursts and other features of sounds that are identifiable by automated techniques may ultimately lead to improved pest detection applications and new insight into pest behavior. PMID:18613585

Mankin, R W; Smith, M T; Tropp, J M; Atkinson, E B; Jong, D Y

2008-06-01

168

Temporal patterning of neuroblasts controls Notch-mediated cell survival through regulation of Hid or Reaper.  

PubMed

Temporal patterning of neural progenitors is one of the core mechanisms generating neuronal diversity in the central nervous system. Here, we show that, in the tips of the outer proliferation center (tOPC) of the developing Drosophila optic lobes, a unique temporal series of transcription factors not only governs the sequential production of distinct neuronal subtypes but also controls the mode of progenitor division, as well as the selective apoptosis of Notch(OFF) or Notch(ON) neurons during binary cell fate decisions. Within a single lineage, intermediate precursors initially do not divide and generate only one neuron; subsequently, precursors divide, but their Notch(ON) progeny systematically die through Reaper activity, whereas later, their Notch(OFF) progeny die through Hid activity. These mechanisms dictate how the tOPC produces neurons for three different optic ganglia. We conclude that temporal patterning generates neuronal diversity by specifying both the identity and survival/death of each unique neuronal subtype. PMID:25171415

Bertet, Claire; Li, Xin; Erclik, Ted; Cavey, Matthieu; Wells, Brent; Desplan, Claude

2014-08-28

169

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

E-print Network

Are obsidian subsources meaningful units of analysis?: temporal and spatial patterning Archaeologists frequently assign artifacts to chemically discrete subsignatures of major obsidian sources. While reserved. Keywords: Obsidian fingerprinting; Intra-source variability; Coso Volcanic Field; California

170

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

171

Remating by female Mediterranean fruit flies ( Ceratitis capitata, Diptera: Tephritidae): Temporal patterns and modulation by male condition  

Microsoft Academic Search

We determined the temporal pattern of female remating in the Mediterranean fruit fly, Ceratitis capitata, and how mating with sterile males affects remating. In addition, we examined the hypotheses that sterile male nutrition and age affect the subsequent receptivity of their mates. Temporally, female receptivity varied significantly throughout the experimental period. Relatively high levels of remating (14%) on the days

Sagi Gavriel; Yoav Gazit; Boaz Yuval

2009-01-01

172

Spatial and temporal patterns in the diet of the Andean condor: ecological replacement of native fauna by exotic  

E-print Network

Spatial and temporal patterns in the diet of the Andean condor: ecological replacement of native the existence of adequate and safe food supplies in the wild. Early reports on Andean condors Vultur gryphus and temporal variation of the condors' diet to determine which species are being consumed by condors

Donázar, José A.

173

Mapping nanoscale domain patterns in ferroelectric ceramics by atomic force acoustic microscopy and piezoresponse force microscopy  

NASA Astrophysics Data System (ADS)

In this paper, nanoscale domain patterns of ferroelectric ceramics were investigated by both atomic force acoustic microscopy (AFAM) and piezoresponse force microscopy (PFM). First, we applied the dual frequency resonance tracking (DFRT) technique on AFAM and realized nanoscale modulus mapping. Then we comparatively mapped the nanoscale domain patterns in a PZT ceramics using PFM, single-frequency AFAM, and DFRT AFAM in the same scanning area. Results show that PFM can give the best contrast domain patterns and is not sensitive to cantilever stiffness. In comparison, both modes of AFAM are sensitive to cantilever stiffness and can give good contrast of domains only using very stiff cantilevers. Furthermore, both modes of AFAM can map the subsurface domain structures and the grain boundaries clearly while PFM usually cannot. Based on the resonance-frequency image obtained by the DFRT AFAM, we also obtained the nanoscale modulus of the whole scanning area which may help understand the possible domain movement under mechanical or electric fields. Finally, we suggest that, to characterize the nanoscale domain properties in ferroelectrics, PFM plus resonance tracking AFAM is the best choice.

Zhou, X. L.; Li, F. X.; Zeng, H. R.

2013-05-01

174

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

175

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

176

Temporal and spatial patterns of colonization, reemergence, and emergence of the southwestern pine beetle, Dendroctonus fontalis Zimm: (Coleoptera : Scolytidae)  

E-print Network

TEMPORAL AND SPATIAL PATTERNS OF COLONIZATION, REEMERGENCE, AND EMERGENCE OF THE SOUTHERN PINE BEETLE, DENDROCTONUS FRONTALIS ZIMM. (COLE OPTERA: SCOLYTIDAE) A Thesis by WALTER SCOTT FARGO Submitted to the Graduate College of Texas A...&M University partial fulfillment of the requirement for the degree of MAS TE R OF SC I E NC E December 1977 Major Subject: Entomology TEMPORAL AND SPATIAL PATTERNS OF COLONIZATION, REEMERGENCE ) AND EMERGENCE OF THE SOUTHERN PINE BEETLE, DENDROCTONUS...

Fargo, Walter Scott

2012-06-07

177

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

E-print Network

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

Vorperian, Houri K.

178

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

PubMed

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

Lal, A; Hales, S

2015-02-01

179

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

PubMed

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

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

2014-01-01

180

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

PubMed Central

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

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

2014-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

182

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

183

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.

184

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

185

Ictal chronology and interictal spikes predict perfusion patterns in temporal lobe epilepsy: a multivariate study.  

PubMed

Typical (TPP) and atypical (APP) perfusion patterns (PP) may be seen in ictal SPECT of patients with temporal lobe epilepsy (TLE). APP may pose problem in the lateralization of the epileptogenic zone (EZ). We aimed to investigate predictive variables for the occurrence of TPP and APP. Fifty-one TLE patients were submitted to successful anterior-mesial temporal lobectomy. Univariate (UVA) and multivariate (MVA) analysis were performed upon clinical data, distribution of interictal spikes, and ictal chronology of seizures. From MVA, a final predictive model (FPM) was determined to better predict TPP and APP. Forty patients showed TPP (78.5%) and 11 patients APP (21.5%). Accuracy of ictal SPECT was higher in the unilateral (UIS) than in the bilateral (BIS) interictal spikes group (P = 0.05). FPM showed that patients exhibiting BIS, with shorter proportion of the electrographic seizure occurring after completion of tracer injection, and longer clinical than EEG seizure duration had more APP (P = 0.003). Generalized tonic-clonic seizures did not result in more APP. We concluded that analysis of ictal SPECT in TLE requires the knowledge of TPP and APP, the distribution of interictal spikes on temporal lobes and the ictal chronology of seizures. BIS showed that beyond a more complex epileptogenicity and seizure propagation, they may also lead to APP. PMID:15158707

Wichert-Ana, Lauro; Velasco, Tonicarlo Rodrigues; Terra-Bustamante, Vera Cristina; Alexandre, Veriano; Guarnieri, Ricardo; Walz, Roger; Kato, Mery; Araújo, Whemberton Martins; Carlotti, Carlos Gilberto; Araújo, David; Carlos Dos Santos, Antonio; Sakamoto, Américo Ceiki

2004-07-01

186

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

PubMed

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

Fostick, Leah; Babkoff, Harvey

2013-01-01

187

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

188

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

PubMed Central

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

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

2015-01-01

189

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

PubMed

Amphibian ranaviruses have been documented as causes of mass mortality in amphibian populations throughout the world. The temporal and spatial dynamics of ranavirus infections when epidemics are not apparent remains unclear. To address this question, we collected tissue samples from 2003 to 2006 in 4 geographically separated tiger salamander Ambystoma tigrinum nebulosum host populations on the Kaibab Plateau in northern Arizona. We tested for Ambystoma tigrinum virus (ATV), a lethal ranavirus of tiger salamanders, calculated ATV prevalence for each sampling date, and examined temporal and spatial patterns by quantifying the annual level of ATV synchrony among populations using the intraclass correlation coefficient. Salamander populations were commonly infected with ATV. We observed no morbidity or mortality in these populations even as ATV prevalence values varied from 0 to 57%. Infection prevalence across the landscape was more similar within a given year than between years. There was no statistically significant spatial pattern in prevalence across the landscape. Our findings highlight the need to explore new hypotheses regarding the population level impact of these pathogens on amphibian communities. PMID:19593927

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

2009-05-27

190

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

PubMed Central

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

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

2007-01-01

191

Hyperpigmentation in North Sea dab Limanda limanda. I. Spatial and temporal patterns and host effects.  

PubMed

Hyperpigmentation is a term describing a specific pigment anomaly affecting common dab Limanda limanda in the North Sea and, less frequently, in adjacent areas, e.g. the English Channel, Irish and Celtic Seas, western Baltic Sea and Icelandic waters. Other North Sea flatfish species are also affected, but at a markedly lower prevalence. The condition is characterised by the occurrence of varying degrees of green to black patchy pigment spots in the skin of the upper (ocular) body side and pearly-white pigment spots in the skin of the lower (abocular) body side. In the course of fish disease monitoring programmes carried out by Germany and the UK (England and Scotland), a pronounced spatial pattern of hyperpigmentation has been detected in the North Sea. An increase in prevalence has been recorded in almost all North Sea areas studied in the past 2 decades. The prevalence recorded in hot spot areas of the condition increased from 5 to >40% between 1988 and 2009. Analysis of the German data indicates that the prevalence and intensity (degree of discolouration) of hyperpigmentation increase with size and age, indicating a temporal progression of the condition with size and age. Intense hyperpigmentation is associated with increased growth (length) and decreased condition factor. Potential causes of the condition (UV-B radiation nutrition, water temperature increase, demographic changes) and, in particular, of the spatial/temporal patterns recorded as well as the relationship to host-specific factors (sex, age, length, growth, condition factor) are discussed. PMID:23482381

Grütjen, F; Lang, T; Feist, S; Bruno, D; Noguera, P; Wosniok, W

2013-03-13

192

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

PubMed

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

Hansen, Gretchen J A; Carey, Cayelan C

2015-01-01

193

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

PubMed Central

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

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

2012-01-01

194

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

PubMed

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

Behar, Hilla; Brenner, Naama; Louzoun, Yoram

2014-09-01

195

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

PubMed Central

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

Bosiger, Yoland J.; McCormick, Mark I.

2014-01-01

196

Imaging Spatial and Temporal Patterns of Landslide Movement with Ground-Based Radar Interferometry  

NASA Astrophysics Data System (ADS)

Ground-based interferometric radar (GBIR) provides a means of addressing questions about landslides that involve monitoring changes across large areas (<10 km2) with high spatial (<1 mm) and temporal precision (<1 hr). Recent studies have shown that landslide displacement rates may exhibit sensitivity to unlikely sources, such as atmospheric tides. This study applies GBIR to measure temporal and spatial patterns of movement in a slow-velocity slide on the west side of the Colorado Front Range. Multiple deployments of the GBIR permit assessing long-term (seasonal) variations in slide kinematics, which compared favorably with ground-truth measurements using more conventional surveying techniques. Each GBIR deployment involves long observation sessions (5 - 36 hours) with images acquired every 7.5 - 15 minutes. The data redundancy permits rigorous time-series analysis that results in 0.3 - 0.4 mm positional uncertainties. The time series is further constrained by imposing a 'no back-slip' condition that is justified by the nearly horizontal viewing geometry facing in the slide's direction of transport. The slide demonstrates significant seasonal variations that correspond with variations in groundwater measured by piezometric wells in the study area. These are primarily driven by variations in spring snow melt and precipitation. Additionally, short-span time series for individual observation sessions suggest short term variations in displacement rate over periods of several hours. One possible model for this quasi stick-slip behavior may involve release of excess fluid pressure during slide movement that increases frictional coupling at the base of the slide. As a tool for geodetic imaging, offers a significant improvement in temporal and spatial resolution compared with satellite and airborne radar interferometry. The sensitivity and temporal sampling of GBIR complement well the spatial resolution and 3-dimensional displacements measured with other methods, such as terrestrial laser scanners.

Gomez, F.; Held, B. M.; Lowry, B. W.; Mooney, M.; Zhou, W.; Grasmick, J.

2012-12-01

197

Spatio-temporal pattern analysis of land use/cover change trajectories in Xihe watershed  

NASA Astrophysics Data System (ADS)

Human-induced land use/cover change has been considered to be one of the most important parts of global environmental changes. In loess hilly and gully regions, to prevent soil loss and achieve better ecological environments, soil conservation measures have been taken during the past decades. The main objective of this study is to quantify the spatio-temporal variability of land use/cover change spatial patterns and make preliminary estimation of the role of human activity in the environmental change in Xihe watershed, Gansu Province, China. To achieve this objective, the methodology was developed in two different aspects, that is, (1) analysis of change patterns by binary image of change trajectories overlaid with different natural geographic factors, in which Relative Change Intensity (RCI) metric was established and used to make comparisons, and (2) analysis based on pattern metrics of main trajectories in the study area. Multi-source and multi-temporal Remote Sensing (RS) images (including Landsat ETM+ (30 June 2001), SPOT imagery (21 November 2003 and 5 May 2008) and CBERS02 CCD (5 June 2006)) were used due to the constraints of the availability of remotely sensed data. First, they were used to extract land use/cover types of each time node by object-oriented classification method. Classification results were then utilized in the trajectory analysis of land use/cover changes through the given four time nodes. Trajectories at every pixel were acquired to trace the history of land use/cover change for every location in the study area. Landscape metrics of trajectories were then analyzed to detect the change characteristics in time and space through the given time series. Analysis showed that most land use/cover changes were caused by human activities, most of which, under the direction of local government, had mainly led to virtuous change on the ecological environments. While, on the contrary, about one quarter of human-induced changes were vicious ones. Analysis through overlaying binary image of change trajectories with natural factors can efficiently show the spatio-temporal distribution characteristics of land use/cover change patterns. It is found that in the study area RCI of land use/cover changes is related to the distance to the river line. And there is a certain correlation between RCI and slope grades. However, no obvious correlation exists between RCI and aspect grades.

Wang, Dongchuan; Gong, Jianhua; Chen, Liding; Zhang, Lihui; Song, Yiquan; Yue, Yujuan

2012-02-01

198

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

199

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

PubMed Central

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

Gauvin, Laetitia; Panisson, André; Cattuto, Ciro

2014-01-01

200

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

PubMed

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

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

2013-01-01

201

Comparing Spatial and Temporal Patterns of Landslides and Rainfall, Using Remote Sensing  

NASA Astrophysics Data System (ADS)

Although many non-climate factors contribute to slope instability, the intensity and duration of rainfall has been strongly linked to the initiation of shallow, rapidly moving landslides. Our primary focus is to characterize the spatial and temporal patterns of rainfall during an intense storm, using ground-based radar, for comparison with the distribution of associated landslides. Unlike rain gauges (which are sparsely distributed), radar can provide meteorological data of a high spatial and temporal resolution, giving information on the location, size, and intensity, and duration of storms cells. NEXRAD radar data represents the reflectivity of raindrops (and thus intensity of rainfall) in a storm, and is produced every six minutes. During February 6th-9th, 1996, a 100-year storm occurred in Oregon and Washington, generating 140 to 180% the average seasonal rainfall, in some areas spawning thousands of landslides. Our study site in the Tillamook State Forest is a steep and highly dissected landscape near the Oregon Coast, with a variety of forest stand ages. Mapped from a 1996 aerial photo set, landslides in different forest stand ages appear clustered, despite the general uniformity of other landscape characteristics, suggesting that systematic variations in rainfall intensity may be the primary factor controlling landslide distribution. At a distance of about 60 km from the Portland NEXRAD station, the region is sufficiently close as to minimize most topographic and resolution issues that can affect radar accuracy. We processed Level II NEXRAD data at 1 km2 spatial resolution, and compared it with landslide location and properties. Preliminary results indicate that areas with high radar reflectivity (a proxy for storm intensity) correlate with the pattern of landsliding. Additional factors such as slope, topographic geometry, land use, stand age, geology, and soil properties are simultaneously considered as slope stability factors. Ground-based radar is a relatively new tool in estimating patterns of precipitation, and may be highly useful for hazard mitigation, by establishing well-constrained relationships between rainfall intensity and shallow landslides.

MacLeod, A. J.; Roering, J.; Yuter, S.

2005-12-01

202

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

PubMed

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

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

2013-08-01

203

“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

204

Excitation of magnetization dynamics in patterned thin films using surface acoustic waves  

NASA Astrophysics Data System (ADS)

The investigation of magnetization dynamics often involves the application of magnetic field or light pulses on very short time scales. Here we outline an alternative method that utilizes the changes in magnetic anisotropy associated with magneto-elastic strain. Surface Acoustic Wave (SAW) transducers are readily available at high frequencies (>10GHz), and provide an ideal method for straining thin film magnetic elements. SAWs propagate across a piezoelectric substrate, alternately compressing and expanding the surface with a wavelength and period that depends only on the propagation speed of the piezoelectric and the spacing of the interdigital transducer (IDT) that produces the SAW. Patterning thin film magnetic nanostructures at a spacing identical to the SAW wavelength ensures that all elements will be in phase as the SAW passes through. Passage of the SAW through a magnetic element leads to expansion and compression along the SAW propagation direction dynamically altering the easy axis of magnetization at ultra high frequencies. The subsequent dynamics can be probed using the Kerr effect. Using an IDT of 100 fingers operating at 87.2 MHz with realistic insertion losses, an array of 30nm thick, 10x20?m rectangular Co bars require voltages of ˜3.3V to fully switch the magnetization from the easy to hard axis without the application of an external field. Funded by NSF-MRSEC DMR-0820521.

Baruth, A.; Adenwalla, S.

2009-03-01

205

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

2007-09-01

206

Differentiation of bacterial colonies and temporal growth patterns using hyperspectral imaging  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

207

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

PubMed Central

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

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

2013-01-01

208

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

PubMed Central

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

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

2013-01-01

209

Spatial and temporal patterns of exhumation across the Venezuelan Andes: Implications for Cenozoic Caribbean geodynamics  

NASA Astrophysics Data System (ADS)

The Venezuelan Andes formed by complex geodynamic interaction between the Caribbean Plate, the Panamá Arc, the South American Plate and the continental Maracaibo block. We study the spatial and temporal patterns of exhumation across the Venezuelan Andes using 47 new apatite fission track (AFT) ages as well as topographic analyses. This approach permits the identification of at least seven tectonic blocks (Escalante, Cerro Azul, Trujillo, Caparo, Sierra Nevada, Sierra La Culata and El Carmen blocks) with contrasting exhumation and cooling histories. The Sierra Nevada, Sierra La Culata and El Carmen blocks, located in the central part of the Venezuelan Andes and separated by the Boconó fault system, cooled rapidly but diachronously during the late Miocene-Pliocene. Major surface uplift and exhumation occurred in the Sierra Nevada block since before 8 Ma. A second phase of uplift and exhumation affected the El Carmen and Sierra La Culata blocks to the north of the Boconó fault during the late Miocene-Pliocene. The highest topography and steepest relief of the belt coincides with these blocks. The Caparo and Trujillo blocks, located at the northeastern and southwestern ends of the orogen, cooled more slowly from the Oligocene to the late Miocene. These blocks are characterized by significantly lower mean elevations and slightly lower mean slopes than the central blocks. Unraveling the cooling history of the individual blocks is important to better understand the control of preexisting faults and regional Caribbean geodynamics on the evolution of the Venezuelan Andes. Our data indicate a strong control of major preexisting fault zones on exhumation patterns and temporal correlation between phases of rapid exhumation in different blocks with major tectonic events (e.g., collision of the Panamá arc; rotation of the Maracaibo block).

Bermúdez, Mauricio A.; Kohn, Barry P.; van der Beek, Peter A.; Bernet, Matthias; O'Sullivan, Paul B.; Shagam, Reginald

2010-10-01

210

Temporal patterns in appearance of sooty blotch and flyspeck fungi on apples.  

PubMed

Sooty blotch and flyspeck (SBFS) is a complex of about 80 fungal species that blemish the surface of apple fruit in humid regions worldwide. The dark colonies become visible in mid- to late summer, reducing the value of fresh fruit. Although many SBFS species can co-occur in the same orchard and even on the same apple, little is known about temporal patterns of these species, including the timing of colony appearance. To test the hypothesis that colonies of SBFS species appear on apples at characteristic times during the growing season, 50 apples were monitored weekly at three Iowa orchards in 2006 and six orchards in 2007 and 2008. However, a mean of 24.3 apples per orchard was assessed at harvest because of apple drop throughout the season. Colonies were marked with colored pens as they appeared. After harvest and after storage of apples at 2 °C for 3 months, SBFS colonies on each fruit were counted and classified by morphology, and a representative subset of colonies was excised from the fruit and preserved on dried peels for species identification using rDNA. Seventeen species were identified. Stomiopeltis spp. RS1 and RS2 appeared on apples 10 to 14 days before other SBFS taxa. Dissoconium aciculare was generally the last species to appear on apple fruit, and it continued to appear during postharvest storage. The most prevalent taxa in Iowa orchards were also the most abundant. Diversity of SBFS fungi in an orchard was positively correlated with cumulative hours of surface wetness hours due to rainfall or dew, which is believed to favor growth of SBFS fungi. Species-specific information about temporal patterns of appearance on apple fruit may lead to improved SBFS management strategies. PMID:22832919

Batzer, J C; Sisson, A J; Harrington, T C; Mayfield, D A; Gleason, M L

2012-11-01

211

An assessment of factors controlling spatial and temporal patterns of stream discharge in forested mountain watersheds  

NASA Astrophysics Data System (ADS)

Quantification of the timing and spatial patterns of water delivery to the stream network in forested mountain catchments is important for water use planning, stream chemistry, and in-stream biota. However, understanding the factors that contribute to spatio-temporal patterns of stream discharge remains a challenge due to catchment heterogeneity such as topography, vegetation, and geology. In order to identify watershed structural controls on accumulation of stream flow, we examined the differences in stream discharge at approximately 200m increments along the stream networks of five nested mountain catchments ranging in size from 3.18 to 23 km2 in the Tenderfoot Creek Experimental Forest, Montana, USA. We performed dilution gauging throughout peak stream flow to base flow in order to quantify the difference in discharge between each reach and develop stage-discharge relationships at each monitoring location (hourly discharge measurements at 52 sites). Each watershed exhibited strong differences in the spatial patterns of water delivery across stream networks of different structure. For each reach, we quantified topographic, vegetative, and geologic indices from Airborne Laser Swath Mapping derived digital elevation models and remotely sensed vegetation attributes. These indices represent the propensity for the stream to gain or lose water from the groundwater system. Preliminary analyses suggest that each watershed has unique topographic, geologic, and vegetative properties that lead to the observed patterns in stream yield. Additionally, we predict that the dominant controls shift from peak snowmelt through the recession to low flow. These findings contribute to improved understanding of factors leading to the timing and nature of delivery of water from uplands to streams in forested mountain watersheds.

Bergstrom, A.; Jencso, K. G.; McGlynn, B. L.; Hayes, K. D.

2013-12-01

212

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

NASA Astrophysics Data System (ADS)

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

Tallaksen, Lena M.; Stahl, Kerstin

2014-05-01

213

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

USGS Publications Warehouse

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

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

2008-01-01

214

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

NASA Astrophysics Data System (ADS)

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

Ibrahim, Hesham M.; Huggins, David R.

2011-07-01

215

Distinct temporal pattern of T cell receptor signals during positive versus negative selection in situ  

PubMed Central

The recognition by the T cell receptor (TCR) of self peptides presented by the major histocompatibility complex (MHC) controls T cell fate in the thymus, with weak signals inducing survival (the process of positive selection) and stronger signals inducing death (negative selection). In vitro studies have indicated that ligands that give rise to positive selection induce a low, but sustained, pattern of TCR signaling; however, the temporal pattern of TCR signaling in thymocytes that are presented peptide by MHC class I (MHC class I restriction) in they thymus, under conditions that support positive selection, are unknown. Here, we addressed this question by examining intracellular calcium (Ca2+) dynamics and migratory changes in thymocytes undergoing positive and negative selection in thymic slices. We found that brief, serial signaling events that were separated by migratory periods and low cytosolic Ca2+ correlated with the positive selection of MHC class I–restricted thymocytes, whereas sustained signaling and arrest of thymocytes were associated with negative selection. Low avidity peptides and the presentation of peptides by cortical thymic epithelial 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 is an important feature that distinguishes between positive and negative selection. PMID:24129702

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

2014-01-01

216

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

PubMed

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

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

2013-01-01

217

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

218

Temporal and histological evaluation of melatonin patterns in a 'basal' metazoan.  

PubMed

While recent advances suggest functional pleiotropy of melatonin in higher organisms, an understanding of the biological significance of this ancient molecule in early evolutionary groups is lacking. Here, endogenous melatonin production was identified for the first time in the sea anemone Actinia equina, a nonsymbiotic hexacorallian cnidarian. Day/night activity profiles of melatonin in this anemone indicated that melatonin levels oscillate with significant nocturnal peaks. However, dynamic changes in melatonin concentration did not persist under constant dark conditions and therefore were not circadian in nature. Thus, the oscillating pattern of melatonin in A. equina is presumed to be the result of alternative, simpler melatonin control mechanism that likely involves direct regulation by the daily photocycle. As nocturnal melatonin signals still potentially provide 'time-of-day' information and can illustrate the seasonally changing length of the biological night, we hypothesize that melatonin may be relevant to temporal coordination of timed processes also in anthozoans. Spatial patterns of melatonin distribution found in this study indicate abundant melatonin distribution in the endodermal filaments wrapped around gametes. This finding supports the possibility that one of the melatonin-responsive processes in this basal metazoan species may involve reproductive functions. PMID:22506978

Roopin, Modi; Levy, Oren

2012-10-01

219

Spatial and temporal expression patterns of chitinase genes in developing zebrafish embryos.  

PubMed

Chitinases and chitinase like proteins play an important role in mammalian immunity and functions in early zebrafish development have been suggested. Here we report identification of six zebrafish chitinases and chitinase like proteins (called CHIA.1-6) belonging to the glycoside hydrolase family 18, and determine their spatial and temporal expression at 10 stages of zebrafish development. CHIA.4 is highly maternally expressed and it is expressed 100 fold above any other CHIA gene at zygote through to blastula stage. Later, after the maternal to zygotic transition, CHIA.4 expression decreases to the same level as CHIA.5 and CHIA.6. Subsequently, CHIA.1, CHIA.2, CHIA.3 and CHIA.4, CHIA.5, CHIA.6 each follow distinct paths in terms of expression levels. Until 4 days post fertilization the spatial expression patterns of all six CHIA genes overlap extensively, with expression detected predominantly in vascular, ocular and intestinal tissues. At 5 days post fertilization CHIA.1, CHIA.2 and CHIA.3 are expressed almost exclusively in the stomach, whereas CHIA.4, CHIA.5 and CHIA.6 are also prominently expressed in the liver. These different expression patterns may contribute to the establishment of a basis on which functional analysis in older larvae may be founded. PMID:24418193

Koch, Bjørn E V; Stougaard, Jens; Spaink, Herman P

2014-03-01

220

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

PubMed Central

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

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

2012-01-01

221

Decoding temporal structure in music and speech relies on shared brain resources but elicits different fine-scale spatial patterns.  

PubMed

Music and speech are complex sound streams with hierarchical rules of temporal organization that become elaborated over time. Here, we use functional magnetic resonance imaging to measure brain activity patterns in 20 right-handed nonmusicians as they listened to natural and temporally reordered musical and speech stimuli matched for familiarity, emotion, and valence. Heart rate variability and mean respiration rates were simultaneously measured and were found not to differ between musical and speech stimuli. Although the same manipulation of temporal structure elicited brain activation level differences of similar magnitude for both music and speech stimuli, multivariate classification analysis revealed distinct spatial patterns of brain responses in the 2 domains. Distributed neuronal populations that included the inferior frontal cortex, the posterior and anterior superior and middle temporal gyri, and the auditory brainstem classified temporal structure manipulations in music and speech with significant levels of accuracy. While agreeing with previous findings that music and speech processing share neural substrates, this work shows that temporal structure in the 2 domains is encoded differently, highlighting a fundamental dissimilarity in how the same neural resources are deployed. PMID:21071617

Abrams, Daniel A; Bhatara, Anjali; Ryali, Srikanth; Balaban, Evan; Levitin, Daniel J; Menon, Vinod

2011-07-01

222

Analysis of spatio-temporal brain imaging patterns by Hidden Markov Models and serial MRI images.  

PubMed

Brain changes due to development and maturation, normal aging, or degenerative disease are continuous, gradual, and variable across individuals. To quantify the individual progression of brain changes, we propose a spatio-temporal methodology based on Hidden Markov Models (HMM), and apply it on four-dimensional structural brain magnetic resonance imaging series of older individuals. First, regional brain features are extracted in order to reduce image dimensionality. This process is guided by the objective of the study or the specific imaging patterns whose progression is of interest, for example, the evaluation of Alzheimer-like patterns of brain change in normal individuals. These regional features are used in conjunction with HMMs, which aim to measure the dynamic association between brain structure changes and progressive stages of disease over time. A bagging framework is used to obtain models with good generalization capability, since in practice the number of serial scans is limited. An application of the proposed methodology was to detect individuals with the risk of developing MCI, and therefore it was tested on modeling the progression of brain atrophy patterns in older adults. With HMM models, the state-transition paths corresponding to longitudinal brain changes were constructed from two completely independent datasets, the Alzheimer Disease Neuroimaging Initiative and the Baltimore Longitudinal Study of Aging. The statistical analysis of HMM-state paths among the normal, progressive MCI, and MCI groups indicates that, HMM-state index 1 is likely to be a predictor of the conversion from cognitively normal to MCI, potentially many years before clinical symptoms become measurable. PMID:24706564

Wang, Ying; Resnick, Susan M; Davatzikos, Christos

2014-09-01

223

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. PMID:23486844

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

2013-01-01

224

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

Microsoft Academic Search

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

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

1996-01-01

225

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....

226

Model of Cellular and Network Mechanisms for Odor-Evoked Temporal Patterning in the Locust Antennal Lobe  

Microsoft Academic Search

Locust antennal lobe (AL) projection neurons (PNs) respond to olfactory stimuli with sequences of depolarizing and hyperpolarizing epochs, each lasting hundreds of milliseconds. A computer simulation of an AL network was used to test the hypothesis that slow inhibitory connections between local neurons (LNs) and PNs are responsible for temporal patterning. Activation of slow inhibitory receptors on PNs by the

Maxim Bazhenov; Mark Stopfer; Mikhail Rabinovich; Henry D. I. Abarbanel; Terrence J. Sejnowski; Gilles Laurent

2001-01-01

227

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

Microsoft Academic Search

Temporal and spatial patterns of recruitment (R) and spawning stock biomass (S) variability were compared among functionally analogous species and similar feeding guilds from six marine ecosystems. Data were aggregated into four regions including the Gulf of Maine\\/Georges Bank, the Norwegian\\/Barents Seas, the eastern Bering Sea, and the Gulf of Alaska. Variability was characterized by calculating coefficients of variation and

Bernard A. Megrey; Jonathan A. Hare; William T. Stockhausen; Are Dommasnes; Harald Gjøsæter; William Overholtz; Sarah Gaichas; Georg Skaret; Jannike Falk-Petersen; Jason S. Link; Kevin D. Friedland

2009-01-01

228

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

Microsoft Academic Search

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

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

2008-01-01

229

Abstract Odors elicit spatio-temporal patterns of activity in the olfactory bulb of vertebrates and the  

E-print Network

in olfactory learning remains to be investigated. Keywords Learning and memory Ã? Olfactory coding Ã? CalciumAbstract Odors elicit spatio-temporal patterns of activity in the olfactory bulb of vertebrates olfactory learning. These studies pose a conundrum: how can an animal learn to efficiently respond

Menzel, Randolf - Institut für Biologie

230

Spatial and Temporal Patterns in Erosion from Forest Roads1 Charles H. Luce and Thomas A. Black  

E-print Network

Spatial and Temporal Patterns in Erosion from Forest Roads1 Charles H. Luce and Thomas A. Black ABSTRACT Erosion from forest roads is an important contribution to the sediment budget of many forested by the second year and 90% recovery by the third year. 1. INTRODUCTION 1.1 The Role of Road Surface Erosion

231

Spatio-temporal expression patterns of Aurora kinases A, B and C in bovine oocytes during meiotic maturation.2  

E-print Network

1 Spatio-temporal expression patterns of Aurora kinases A, B and C in bovine oocytes during meiotic-mail: uzbekova@tours.inra.fr24 Short title: Aurora kinases in bovine oocyte meiosis26 Summary sentence: Aurora in meiosis that are different from those in28 mitosis. Key words: Aurora kinases, bovine, oocyte, meiosis30

Boyer, Edmond

232

Identifying Temporal Patterns and Key Players in Document Collections Benyah Shaparenko Rich Caruana Johannes Gehrke Thorsten Joachims  

E-print Network

these questions for general document collections, we impose that our algorithms must work without meta- data in a col- lection of documents, however, there is quite a body of work alrIdentifying Temporal Patterns and Key Players in Document Collections Benyah Shaparenko Rich

Joachims, Thorsten

233

Pattern-Based Real-Time Feedback for a Temporal Bone Simulator Department of Computing and Information Systems  

E-print Network

and Information Systems University of Melbourne James Bailey Department of Computing and Information Systems of the procedure cor- rectly and provides constructive feedback to assist surgical trainees in improvingPattern-Based Real-Time Feedback for a Temporal Bone Simulator Yun Zhou Department of Computing

Bailey, James

234

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

ERIC Educational Resources Information Center

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

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

2008-01-01

235

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

236

Temporal and spatial patterns of Bartonella infection in black-tailed prairie dogs (Cynomys ludovicianus).  

PubMed

We describe the temporal dynamics and spatial distribution of Bartonella in black-tailed prairie dogs (Cynomys ludovicianus) based on a longitudinal study conducted in 20 black-tailed prairie dog (BTPD) colonies in Boulder County, CO from 2003 to 2005. Bartonella infection was widely distributed in all colonies with an overall prevalence of 23.1%, but varied by colony from 4.8% to 42.5% and by year from 9.1 to 39.0%, with a marked increase in Bartonella activity in 2005. Levels of bacteremia varied from 40 to 12,000 colony forming units (CFU) per milliliter of BTPD blood, but were highly skewed with a median of 240 CFU. Bartonella infection rates were unimodal with respect to BTPD body mass, first increasing among growing juveniles, then declining among adults. Infection rates exhibited a sigmoidal response to body mass, such that 700g may prove to be a useful threshold value to evaluate the likelihood of Bartonella infection in BTPDs. Bartonella prevalence increased throughout the testing season for each year, as newly emerged juveniles developed bacteremia. Data from recaptured animals suggest that Bartonella infections did not persist in individual BTPDs, which may explain the relatively low prevalence of Bartonella in BTPDs compared to other rodent species. No association was found between Bartonella prevalence and host population density. Prevalence did not differ between males and females. The spatio-temporal pattern of Bartonella infection among colonies suggests epizootic spread from northern to central and southern portions of the study area. The potential significance of the BTPD-associated Bartonella for public health needs to be further investigated. PMID:18176820

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

2008-08-01

237

Neuromolecular Imaging Shows Temporal Synchrony Patterns between Serotonin and Movement within Neuronal Motor Circuits in the Brain  

PubMed Central

The present discourse links the electrical and chemical properties of the brain with neurotransmitters and movement behaviors to further elucidate strategies to diagnose and treat brain disease. Neuromolecular imaging (NMI), based on electrochemical principles, is used to detect serotonin in nerve terminals (dorsal and ventral striata) and somatodendrites (ventral tegmentum) of reward/motor mesocorticolimbic and nigrostriatal brain circuits. Neuronal release of serotonin is detected at the same time and in the same animal, freely moving and unrestrained, while open-field behaviors are monitored via infrared photobeams. The purpose is to emphasize the unique ability of NMI and the BRODERICK PROBE® biosensors to empirically image a pattern of temporal synchrony, previously reported, for example, in Aplysia using central pattern generators (CPGs), serotonin and cerebral peptide-2. Temporal synchrony is reviewed within the context of the literature on central pattern generators, neurotransmitters and movement disorders. Specifically, temporal synchrony data are derived from studies on psychostimulant behavior with and without cocaine while at the same time and continuously, serotonin release in motor neurons within basal ganglia, is detected. The results show that temporal synchrony between the neurotransmitter, serotonin and natural movement occurs when the brain is NOT injured via, e.g., trauma, addictive drugs or psychiatric illness. In striking contrast, in the case of serotonin and cocaine-induced psychostimulant behavior, a different form of synchrony and also asynchrony can occur. Thus, the known dysfunctional movement behavior produced by cocaine may well be related to the loss of temporal synchrony, the loss of the ability to match serotonin in brain with motor activity. The empirical study of temporal synchrony patterns in humans and animals may be more relevant to the dynamics of motor circuits and movement behaviors than are studies of static parameters currently relied upon within the realms of science and medicine. There are myriad applications for the use of NMI to discover clinically relevant diagnoses and treatments for brain disease involving the motor system. PMID:24961434

Broderick, Patricia A.

2013-01-01

238

Spectral structures and radiation patterns of scattering waves in a layered acoustic half-space  

Microsoft Academic Search

Summary  ?Scattering waves in a layered acoustic half-space are analyzed in terms of their spectra, which are sets of wavenumbers for\\u000a which proper and improper eigenfunctions for a layered wave field can be observed. The scattering waves are caused by the\\u000a interaction between an incident plane wave and a low acoustic-velocity area. The boundary-integral equations and the spectral\\u000a form of Green's

T. Touhei

2002-01-01

239

Spatial and temporal seismicity patterns from dynamic trigger by great earthquakes  

NASA Astrophysics Data System (ADS)

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

Johnson, C. W.; Burgmann, R.

2013-12-01

240

Spatial and temporal patterns in the dynamics of analogue accretionary wedges  

NASA Astrophysics Data System (ADS)

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

Santimano, Tasca; Rosenau, Matthias; Oncken, Onno

2014-05-01

241

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. PMID:22165895

2011-01-01

242

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

E-print Network

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

Porter, Warren P.

243

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

PubMed Central

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

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

2010-01-01

244

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

245

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

2013-01-01

246

Spatio-temporal patterns of weekend effects in surface air temperatures in China, 1978-2008  

NASA Astrophysics Data System (ADS)

Spatio-temporal patterns of weekend effects of surface air temperature variables over the continental area of China during the period 1978-2008 were analyzed by statistics and spatial analysis of the homogenized time series from the selected 615 surface meteorological stations of China Meteorological Administration (CMA). Results indicate that (1) there is an evident warming trend over China from 1978 to 2008, with the linear trend rates of Tmean, Tmax, Tmin and DTR being 0.43, 0.41, 0.48, and -0.07 °C/10 a, respectively; (2) weekend temperature effects are statistically significant (? = 0.05) in the annual and seasonal mean (Tmean) and maximum (Tmax) temperatures, but not in the minimum temperature (Tmin) or diurnal temperature range (DTR); And (3) for seasonal time series, Tmean, Tmax and Tmin show negative weekend effect anomalies in spring, summer and autumn, while they have opposite signals — positive weekend effect anomalies in winter. Spatial statistics show that only a minority (less than 30%) of the 615 stations demonstrate weekend effects in all four temperature variables at the ? = 0.10 confidence level. Tmean, Tmax and Tmin have negative weekend effects only in southern-central and southwestern China, while DTR has a positive weekend effect in northwestern and southwestern China. The weekend effects of temperature variables vary with season and region over China. There are different spatial distribution patterns of weekend effect in different temperature variables for different seasons and no evidently opposite signals of weekend effects for winter and summer in Tmean, Tmax, Tmin and DTR over China, 1978-2008.; Fig.1 Spatial distribution map of weekend effects in DTR over China, 1978-2008. Shown as the average for Saturday through Monday minus the average for Wednesday through Friday for each station. Stations significant at ? = 0.05 and 0.10 are filled with dark and light colors, respectively.

Xiong, Y.

2012-12-01

247

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

PubMed Central

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

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

2013-01-01

248

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

249

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

PubMed

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 microm) 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 Carbón I and II 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. PMID:16350362

Gebhart, Kristi A; Malm, William C; Ashbaugh, Lowell L

2005-11-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

251

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

PubMed Central

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

Abaid, Nicole; Porfiri, Maurizio

2010-01-01

252

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

PubMed

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

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

2014-11-01

253

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

PubMed

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

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

2012-10-01

254

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

255

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

256

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

PubMed Central

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

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

2014-01-01

257

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

PubMed

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

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

2014-09-01

258

Temporal patterns of genetic variation for resistance and infectivity in a Daphnia-microparasite system.  

PubMed

Theoretical studies have indicated that the population genetics of host-parasite interactions may be highly dynamic. with parasites perpetually adapting to common host genotypes and hosts evolving resistance to common parasite genotypes. The present study examined temporal variation in resistance of hosts and infectivity of parasites within three populations of Daphnia magna infected with the sterilizing bacterium Pasteuria ramosa. Parasite isolates and host clones were collected in each of two years (1997, 1998) from one population; in two other populations, hosts were collected from both years, but parasites from only the first year. We then performed infection experiments (separately for each population) that exposed hosts to parasites from the same year or made combinations involving hosts and parasites from different years. In two populations, patterns were consistent with the evolution of host resistance: either infectivity or the speed with which parasites sterilized hosts declined from 1997 to 1998. In another population, infectivity, virulence, and parasite spore production did not vary among host-year or parasite-year. For this population, we also detected strong within-population genetic variation for resistance. Thus, in this case, genetic variability for fitness-related traits apparently did not translate into evolutionary change. We discuss a number of reasons why genetic change may not occur as expected in parasite-host systems, including negative correlations between resistance and other traits, gene flow, or that the dynamic process itself may obscure the detection of gene frequency changes. PMID:11475050

Little, T J; Ebert, D

2001-06-01

259

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. PMID:8647389

Wilkinson, H. A.; Greenwald, IVA.

1995-01-01

260

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

PubMed

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

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

2014-05-27

261

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

PubMed

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

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

2014-10-01

262

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

PubMed

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

Quirk, D Adam; Hubley-Kozey, Cheryl L

2014-12-01

263

Acoustic telemetry reveals large-scale migration patterns of walleye in lake huron.  

PubMed

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

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

2014-01-01

264

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

PubMed Central

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

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

2014-01-01

265

Sounds in the natural environment have complex temporal struc-tures that include both slowly and rapidly changing acoustic tran-  

E-print Network

sounds (such as human speech, animal vocal- izations) that convey behaviorally relevant information the possibility that rapid acoustic transients may be encoded by non-synchronized dis- charges. We show that rate

Wang, Xiaoqin

266

Observing temporal patterns of vertical flux through streambed sediments using time-series analysis of temperature records  

NASA Astrophysics Data System (ADS)

SummaryRates of water exchange between surface water and groundwater (SW-GW) can be highly variable over time due to temporal changes in streambed hydraulic conductivity, storm events, and oscillation of stage due to natural and regulated river flow. There are few effective field methods available to make continuous measurements of SW-GW exchange rates with the temporal resolution required in many field applications. Here, controlled laboratory experiments were used to explore the accuracy of analytical solutions to the one-dimensional heat transport model for capturing temporal variability of flux through porous media from propagation of a periodic temperature signal to depth. Column experiments were used to generate one-dimensional flow of water and heat through saturated sand with a quasi-sinusoidal temperature oscillation at the upstream boundary. Measured flux rates through the column were compared to modeled flux rates derived using the computer model VFLUX and the amplitude ratio between filtered temperature records from two depths in the column. Imposed temporal changes in water flux through the column were designed to replicate observed patterns of flux in the field, derived using the same methodology. Field observations of temporal changes in flux were made over multiple days during a large-scale storm event and diurnally during seasonal baseflow recession. Temporal changes in flux that occur gradually over days, sub-daily, and instantaneously in time can be accurately measured using the one-dimensional heat transport model, although those temporal changes may be slightly smoothed over time. Filtering methods effectively isolate the time-variable amplitude and phase of the periodic temperature signal, effectively eliminating artificial temporal flux patterns otherwise imposed by perturbations of the temperature signal, which result from typical weather patterns during field investigations. Although previous studies have indicated that sub-cycle information from the heat transport model is not reliable, this laboratory experiment shows that the sub-cycle information is real and sub-cycle changes in flux can be observed using heat transport modeling. One-dimensional heat transport modeling provides an easy-to-implement, cost effective, reliable field tool for making continuous observations of SW-GW exchange through time, which may be particularly useful for monitoring exchange rates during storms and other conditions that create temporal change in hydraulic gradient across the streambed interface or change in streambed hydraulic conductivity.

Lautz, Laura K.

2012-09-01

267

Spatial and temporal patterns in river ice breakup observed with MODIS and AVHRR time series  

NASA Astrophysics Data System (ADS)

The timing of spring river ice breakup, a major annual event for physical, biological, and human systems on Arctic rivers, has been used to infer regional climate variations over the past century or more. Most observations of ice breakup are recorded as point data taken from selected ground-based stations. It is unknown whether these point observations are fully representative of breakup patterns elsewhere along the course of a river. Here, daily time series of MODIS and AVHRR satellite images are used to remotely sense spatial and temporal patterns in ice breakup along 1600-3300 km lengths of the Lena, Ob', Yenisey, and Mackenzie Rivers. The first day of predominantly ice-free water is visually identified and mapped for the years 1992-1993, 1995-1998, and 2000-2003, with a mean precision of ± 1.75 days. The derived breakup dates show high correlation with ground-based observations, though a slight trend towards earlier satellite-derived dates can be traced to differences in the way ice breakup date is defined. Large ice jams are often observed, particularly at confluences, though smaller ice jams may not be visible due to the limited spatial resolution of the imagery used. At the watershed scale, spatial patterns in breakup seem to be primarily governed by latitude, timing of the spring flood wave, and location of confluences with major tributaries. Interestingly, channel-scale factors such as slope, width, and radius of curvature, which are known to influence ice breakup at the reach scale, do not appear to be major factors at the scale observed here. The degree of similarity between interannual trends in breakup date at distant points along a river is generally high, which supports the use of point-scale data to infer regional climate variations. This similarity does not hold true for the Mackenzie River, where substantial spatial differences in breakup trends are observed. A new variable, spatially integrated breakup date (di), uses weighted spatial averaging to provide a more encompassing measure of breakup timing. The Ob' and Yenisey Rivers show similar trends in spatially integrated breakup date from year to year. In contrast, the Mackenzie and Lena show a remarkably consistent negative correlation, here attributed to sea surface temperature anomalies associated with the Pacific Decadal Oscillation Index.

Pavelsky, T. M.; Smith, L. C.

2004-12-01

268

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

269

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

USGS Publications Warehouse

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

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

2009-01-01

270

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

271

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

272

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

NASA Astrophysics Data System (ADS)

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

Poggio, Laura; Gimona, Alessandro

2015-02-01

273

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

PubMed

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

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

2014-09-01

274

Multivariate temporal pattern analysis applied to the study of rat behavior in the elevated plus maze: methodological and conceptual highlights.  

PubMed

Aim of this article is to illustrate the application of a multivariate approach known as t-pattern analysis in the study of rat behavior in elevated plus maze. By means of this multivariate approach, significant relationships among behavioral events in the course of time can be described. Both quantitative and t-pattern analyses were utilized to analyze data obtained from fifteen male Wistar rats following a trial 1-trial 2 protocol. In trial 2, in comparison with the initial exposure, mean occurrences of behavioral elements performed in protected zones of the maze showed a significant increase counterbalanced by a significant decrease of mean occurrences of behavioral elements in unprotected zones. Multivariate t-pattern analysis, in trial 1, revealed the presence of 134 t-patterns of different composition. In trial 2, the temporal structure of behavior become more simple, being present only 32 different t-patterns. Behavioral strings and stripes (i.e. graphical representation of each t-pattern onset) of all t-patterns were presented both for trial 1 and trial 2 as well. Finally, percent distributions in the three zones of the maze show a clear-cut increase of t-patterns in closed arm and a significant reduction in the remaining zones. Results show that previous experience deeply modifies the temporal structure of rat behavior in the elevated plus maze. In addition, this article, by highlighting several conceptual, methodological and illustrative aspects on the utilization of t-pattern analysis, could represent a useful background to employ such a refined approach in the study of rat behavior in elevated plus maze. PMID:24932963

Casarrubea, M; Magnusson, M S; Roy, V; Arabo, A; Sorbera, F; Santangelo, A; Faulisi, F; Crescimanno, G

2014-08-30

275

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

276

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

PubMed

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

Fisher, Ryan J; Wiebe, Karen L

2006-04-01

277

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

278

Temporal Pattern of the Repeated Bout Effect of Eccentric Exercise on Delayed-Onset Muscle Soreness.  

PubMed

OBJECTIVE: To determine the temporal pattern of the repeated bout effect of eccentric exercise on perceived pain and muscular tenderness associated with delayed-onset muscle soreness (DOMS). DESIGN AND SETTING: Subjects completed 2 identical eccentric exercise bouts separated by 6, 7, 8, or 9 weeks. The experiment was conducted in a biokinetics research laboratory. SUBJECTS: Sixteen male and 15 female untrained subjects (age = 24.59 +/- 4.42 years, height = 171.71 +/- 7.81 cm, weight = 73.00 +/- 11.20 kg). MEASUREMENTS: Two physiologic characteristics of DOMS were measured immediately before and 0, 24, 48, and 72 hours after each eccentric exercise bout. Perceived pain was measured using a visual analog scale (VAS), and muscular tenderness was measured using a punctate tenderness gauge (PTG). RESULTS: Two 4 x 2 x 5 (group x bout x time) analyses of variance with repeated measures on the bout and time factors were performed on the VAS and PTG data. Significant (P <.05) main effects were found for group, bout, and time for the VAS and the PTG data. No significant interactions were detected. Post hoc analysis revealed significantly less perceived pain for the 9-week group than the 8-week group. The 7-week group had significantly less and the 8-week group had significantly more muscular tenderness than any other group. Perceived pain and muscular tenderness were significantly less after exercise bout 2 than after exercise bout 1. All subjects had significantly less perceived pain and muscular tenderness pre-exercise than 0 and 24 hours after the eccentric exercise bouts. CONCLUSIONS: An effective prophylaxis for perceived pain and muscular tenderness associated with DOMS is the performance of an eccentric exercise bout 6 to 9 weeks before a similar exercise bout. PMID:12937441

Cleary, Michelle A; Kimura, Iris F; Sitler, Michael R; Kendrick, Zebulon V

2002-03-01

279

Temporal Pattern of the Repeated Bout Effect of Eccentric Exercise on Delayed-Onset Muscle Soreness  

PubMed Central

Objective: To determine the temporal pattern of the repeated bout effect of eccentric exercise on perceived pain and muscular tenderness associated with delayed-onset muscle soreness (DOMS). Design and Setting: Subjects completed 2 identical eccentric exercise bouts separated by 6, 7, 8, or 9 weeks. The experiment was conducted in a biokinetics research laboratory. Subjects: Sixteen male and 15 female untrained subjects (age = 24.59 ± 4.42 years, height = 171.71 ± 7.81 cm, weight = 73.00 ± 11.20 kg). Measurements: Two physiologic characteristics of DOMS were measured immediately before and 0, 24, 48, and 72 hours after each eccentric exercise bout. Perceived pain was measured using a visual analog scale (VAS), and muscular tenderness was measured using a punctate tenderness gauge (PTG). Results: Two 4 × 2 × 5 (group × bout × time) analyses of variance with repeated measures on the bout and time factors were performed on the VAS and PTG data. Significant (P < .05) main effects were found for group, bout, and time for the VAS and the PTG data. No significant interactions were detected. Post hoc analysis revealed significantly less perceived pain for the 9-week group than the 8-week group. The 7-week group had significantly less and the 8-week group had significantly more muscular tenderness than any other group. Perceived pain and muscular tenderness were significantly less after exercise bout 2 than after exercise bout 1. All subjects had significantly less perceived pain and muscular tenderness pre-exercise than 0 and 24 hours after the eccentric exercise bouts. Conclusions: An effective prophylaxis for perceived pain and muscular tenderness associated with DOMS is the performance of an eccentric exercise bout 6 to 9 weeks before a similar exercise bout. PMID:12937441

Cleary, Michelle A.; Kimura, Iris F.; Sitler, Michael R.; Kendrick, Zebulon V.

2002-01-01

280

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

281

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

282

Systematic temporal patterns in the relationship between housing development and forest bird biodiversity.  

PubMed

As people encroach increasingly on natural areas, one question is how this affects avian biodiversity. The answer to this is partly scale-dependent. At broad scales, human populations and biodiversity concentrate in the same areas and are positively associated, but at local scales people and biodiversity are negatively associated with biodiversity. We investigated whether there is also a systematic temporal trend in the relationship between bird biodiversity and housing development. We used linear regression to examine associations between forest bird species richness and housing growth in the conterminous United States over 30 years. Our data sources were the North American Breeding Bird Survey and the 2000 decennial U.S. Census. In the 9 largest forested ecoregions, housing density increased continually over time. Across the conterminous United States, the association between bird species richness and housing density was positive for virtually all guilds except ground nesting birds. We found a systematic trajectory of declining bird species richness as housing increased through time. In more recently developed ecoregions, where housing density was still low, the association with bird species richness was neutral or positive. In ecoregions that were developed earlier and where housing density was highest, the association of housing density with bird species richness for most guilds was negative and grew stronger with advancing decades. We propose that in general the relationship between human settlement and biodiversity over time unfolds as a 2-phase process. The first phase is apparently innocuous; associations are positive due to coincidence of low-density housing with high biodiversity. The second phase is highly detrimental to biodiversity, and increases in housing density are associated with biodiversity losses. The long-term effect on biodiversity depends on the final housing density. This general pattern can help unify our understanding of the relationship of human encroachment and biodiversity response. PMID:24811862

Pidgeon, Anna M; Flather, Curtis H; Radeloff, Volker C; Lepczyk, Christopher A; Keuler, Nicholas S; Wood, Eric M; Stewart, Susan I; Hammer, Roger B

2014-10-01

283

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

Microsoft Academic Search

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

Denise A Castronovo; Kenneth KH Chui; Elena N Naumova

2009-01-01

284

SN algorithm: analysis of temporal clinical data for mining periodic patterns and impending augury  

PubMed Central

Background EHR (Electronic Health Record) system has led to development of specialized form of clinical databases which enable storage of information in temporal prospective. It has been a big challenge for mining this form of clinical data considering varied temporal points. This study proposes a conjoined solution to analyze the clinical parameters akin to a disease. We have used “association rule mining algorithm” to discover association rules among clinical parameters that can be augmented with the disease. Furthermore, we have proposed a new algorithm, SN algorithm, to map clinical parameters along with a disease state at various temporal points. Result SN algorithm is based on Jacobian approach, which augurs the state of a disease ‘Sn’ at a given temporal point ‘Tn’ by mapping the derivatives with the temporal point ‘T0’, whose state of disease ‘S0’ is known. The predictive ability of the proposed algorithm is evaluated in a temporal clinical data set of brain tumor patients. We have obtained a very high prediction accuracy of ~97% for a brain tumor state ‘Sn’ for any temporal point ‘Tn’. Conclusion The results indicate that the methodology followed may be of good value to the diagnostic procedure, especially for analyzing temporal form of clinical data. PMID:24283349

2013-01-01

285

Understanding spatio-temporal mobility patterns for seniors, child/student and adult using smart card data  

NASA Astrophysics Data System (ADS)

Commutes in urban areas create interesting travel patterns that are often stored in regional transportation databases. These patterns can vary based on the day of the week, the time of the day, and commuter type. This study proposes methods to detect underlying spatio-temporal variability among three groups of commuters (senior citizens, child/students, and adults) using data mining and spatial analytics. Data from over 36 million individual trip records collected over one week (March 2012) on the Singapore bus and Mass Rapid Transit (MRT) system by the fare collection system were used. Analyses of such data are important for transportation and landuse designers and contribute to a better understanding of urban dynamics. Specifically, descriptive statistics, network analysis, and spatial analysis methods are presented. Descriptive variables were proposed such as density and duration to detect temporal features of people. A directed weighted graph G ≡ (N , L, W) was defined to analyze the global network properties of every pair of the transportation link in the city during an average workday for all three categories. Besides, spatial interpolation and spatial statistic tools were used to transform the discrete network nodes into structured human movement landscape to understand the role of transportation systems in urban areas. The travel behaviour of the three categories follows a certain degree of temporal and spatial universality but also displays unique patterns within their own specialties. Each category is characterized by their different peak hours, commute distances, and specific locations for travel on weekdays.

Huang, X.; Tan, J.

2014-11-01

286

Spatial and temporal patterns of larval dispersal in a coral-reef fish metapopulation: evidence of variable reproductive success.  

PubMed

Many marine organisms can be transported hundreds of kilometres during their pelagic larval stage, yet little is known about spatial and temporal patterns of larval dispersal. Although traditional population-genetic tools can be applied to infer movement of larvae on an evolutionary timescale, large effective population sizes and high rates of gene flow present serious challenges to documenting dispersal patterns over shorter, ecologically relevant, timescales. Here, we address these challenges by combining direct parentage analysis and indirect genetic analyses over a 4-year period to document spatial and temporal patterns of larval dispersal in a common coral-reef fish: the bicolour damselfish (Stegastes partitus). At four island locations surrounding Exuma Sound, Bahamas, including a long-established marine reserve, we collected 3278 individuals and genotyped them at 10 microsatellite loci. Using Bayesian parentage analysis, we identified eight parent-offspring pairs, thereby directly documenting dispersal distances ranging from 0 km (i.e., self-recruitment) to 129 km (i.e., larval connectivity). Despite documenting substantial dispersal and gene flow between islands, we observed more self-recruitment events than expected if the larvae were drawn from a common, well-mixed pool (i.e., a completely open population). Additionally, we detected both spatial and temporal variation in signatures of sweepstakes and Wahlund effects. The high variance in reproductive success (i.e., 'sweepstakes') we observed may be influenced by seasonal mesoscale gyres present in the Exuma Sound, which play a prominent role in shaping local oceanographic patterns. This study documents the complex nature of larval dispersal in a coral-reef fish, and highlights the importance of sampling multiple cohorts and coupling both direct and indirect genetic methods in order disentangle patterns of dispersal, gene flow and variable reproductive success. PMID:24917250

Pusack, Timothy J; Christie, Mark R; Johnson, Darren W; Stallings, Christopher D; Hixon, Mark A

2014-07-01

287

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

288

Analysis of the meter of acoustic musical signals  

Microsoft Academic Search

A method is decribed which analyzes the basic pattern of beats in a piece of music, the musical meter. The analysis is performed jointly at three different time scales: at the temporally atomic tatum pulse level, at the tactus pulse level which corresponds to the tempo of a piece, and at the musical measure level. Acoustic signals from arbitrary musical

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

2006-01-01

289

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

PubMed Central

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

2014-01-01

290

Spatial and temporal patterns of Pleistocene biogenic sediment accumulation in the Gulf of Alaska  

NASA Astrophysics Data System (ADS)

Reconstructing the timing and nature of past changes in aquatic productivity in the Gulf of Alaska (GoA) can shed light on the primary processes driving biogeochemical cycling over geologic timescales. Today, Fe is an important micronutrient that limits primary productivity in surface waters beyond the continental shelf in much of the GoA. However, we have a relatively poor understanding of how Fe-delivery processes, combined with changing climate, environmental, and oceanographic conditions, interact to influence primary production over glacial-interglacial timescales. An important first step is to identify the spatial and temporal patterns of increased productivity in the sediment record. Here, we present sedimentologic and physical property data from IODP Expedition 341 and identify intervals where diatom ooze and diatom-rich mud lithofacies are prevalent during the Pleistocene. Among the Expedition 341 recovered cores, were high-recovery intervals in the outer (Site U1417) and inner (U1418) Surveyor Fan, and from a small slope basin at the edge of the continental shelf (Site U1419). In general, greenish gray diatomaceous ooze (containing >50 % diatoms in smear slides) and diatom-rich mud (>25% diatoms) is found in beds ranging in thickness from 20 to 150 cm, interbedded with gray mud that commonly contains lonestones. Ooze is occasionally found immediately overlying volcanic ash. Compared to non-biogenic mud, diatomaceous sediments are generally characterized by lower magnetic susceptibility, natural gamma ray, bulk density, and higher b* color reflectance. At Site U1417, we observe a frequent occurrence of diatomaceous ooze during the middle Pleistocene relative to the early and late Pleistocene. At Site U1418, intervals containing diatom ooze are less common than at U1417 and biogenic sediments are mainly observed within the late Pleistocene portion of the record. However, higher sedimentation rates at U1418 relative to U1417, and the co-occurrence of sand and interbedded mud and silt indicate that clastic sediment dilution may obscure biogenic sediment contribution. At Site U1419, two prominent ~5 m thick intervals of diatomaceous ooze are found (within the uppermost 5 m and between 80 and 90 m composite depth, respectively). Between these intervals are numerous 20 cm thick intervals of biogenic sediment that were likely deposited during the middle or late Pleistocene based on preliminary shipboard age models. Biogenic intervals observed at Expedition 341 sites may be related to increased productivity driven by a combination of the aforementioned processes, but additional chronological and geochemical constraints are needed from all sites to rule out the role that changing sedimentation rates and/or silica dissolution plays in controlling the distribution of ooze in these records.

Moy, C. M.; Bahlburg, H.; Childress, L. B.; Cowan, E. A.; Forwick, M.; Müller, J.; Ribeiro, F.; Ridgway, K. D.; Mix, A. C.

2013-12-01

291

Solar Eclipses on Mars: Spatial and Temporal Patterns in the Motion of the Shadow of Phobos  

NASA Astrophysics Data System (ADS)

The shadow cast by Phobos on the surface of Mars is small and moves rapidly, and can thus provide important relative position information. The size, shape, direction and speed of motion of the shadow evolve over a range of time scales determined by the orientations of Mars and Phobos orbits, and their relative orbital rates. We develop a simple geometric model for the temporal and spatial patterns of Phobos shadows on Mars, and comment on the possibility of using observations of the shadow of Phobos as a supplemental method for determining lander locations. The orbital parameters for the Mars-Phobos system are sufficiently different from the Earth-Moon system that terrestrial eclipse experience is a poor guide. The lunar orbit, with mean angular rate 13.33 deg/day, mean radius 60.2 Earth radii, and variable inclination (18-28 deg) to the equator plane, makes solar eclipses on Earth relatively rare. With an average of 2.38 eclipses per year, only a small fraction of the globe experiences a total eclipse in any given century. In contrast, the orbit of Phobos, with rapid mean motion of 1152 deg/day, small mean radius of 2.7 Mars radii, and negligible inclination of 1.1 deg, provides a favorable eclipse environment. Although the size and orbital distance of Phobos are such that total solar eclipses never occur on Mars, partial eclipses are common, with an average of 3.22 per day throughout most of each annual cycle. The Viking Lander 1 (VL1) camera system captured three Phobos eclipse events on 20, 24, 28, September 1977. On Earth, one would never see a series of eclipses at one location over such a short time scale. However, on Mars it is possible to see two eclipses in one day at a single location. A goal of the present study is to address the likelihood of observing a sequence of eclipses, similar to that observed by Viking 1, at a single site. A substantial portion of the surface in the latitude band between -60 and 60 degrees experiences an eclipse event over the course of a Mars year, with exceptionally dense coverage at low latitudes. Since the predicted landing sites of Beagle 2, and Mars Exploration Rovers are all at lower latitudes, this study suggests ample opportunity for making Phobos shadow observations. Beyond their potential use in establishing lander location, multispectral measurements of shadow duration and intensity can also act as probes of local atmospheric conditions, and subsurface thermal properties.

Comstock, R.; Bills, B.

2003-12-01

292

Two Distinct Modes of Forebrain Circuit Dynamics Underlie Temporal Patterning in the Vocalizations of Young Songbirds  

E-print Network

Accurate timing is a critical aspect of motor control, yet the temporal structure of many mature behaviors emerges during learning from highly variable exploratory actions. How does a developing brain acquire the precise ...

Aronov, Dmitriy

293

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

Microsoft Academic Search

Remotely sensed (RS) data can fruitfully support both research activities and operative monitoring of fire at different temporal and spatial scales with a synoptic view and cost effective technologies. \\

R. Lasaponara

2009-01-01

294

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

E-print Network

There was a long-term decline in northern bobwhite (Colinus virginianus, NBW) abundance since the 1920s, based on the Christmas Bird Count (CBC) data, but with substantial spatial and temporal variations across its range. There were four...

Okay, Atiye Zeynep

2006-04-12

295

Numerical Study of the Complex Temporal Pattern of Spontaneous Oscillation in Bullfrog Saccular Hair Cells  

NASA Astrophysics Data System (ADS)

Hair bundles of the bullfrog sacculus display spontaneous oscillations that show complex temporal profiles. Quiescent intervals are typically interspersed with oscillations, analogous to bursting behavior observed in neural systems. By introducing slow calcium dynamics into the theoretical model of bundle mechanics, we reproduce numerically the multi-mode oscillations and explore the effects of internal parameters on the temporal profiles and the frequency tuning of their linear response functions. We also study the effects of mechanical overstimulation on the oscillatory behavior.

Roongthumskul, Yuttana; Fredrickson-Hemsing, Lea; Kao, Albert; Bozovic, Dolores

2011-11-01

296

Specification inference A specification language Mining with patterns What's next Using patterns to infer first-order temporal  

E-print Network

;Specification inference A specification language Mining with patterns What's next The problem formal system The problem formal system specifications are useful for testing, verification, maintenance, understanding formal system specifications are useful for testing, verification, maintenance, understanding

Rydeheard, David

297

Spatial and Temporal Variation in Color Pattern Morphology in the Tropical Frog, Eleutherodactylus coqui  

E-print Network

and patterns that help to camouflage the animal. Animals that rely on camouflage are generally palatable patterns help to conceal the shape of prey animals and thus can be viewed as a type of camouflage (Owen

298

Spatial and temporal patterns of CO[subscript 2] and CH[subscript 4] fluxes in China's croplands in response to multifactor environmental changes  

E-print Network

The spatial and temporal patterns of CO[subscript 2] and CH[subscript 4] fluxes in China's croplands were investigated and attributed to multifactor environmental changes using the agricultural module of the Dynamic Land ...

REN, WEI

299

Application of pattern recognition techniques to the identification of aerospace acoustic sources  

NASA Technical Reports Server (NTRS)

A pattern recognition system was developed that successfully recognizes simulated spectra of five different types of transportation noise sources. The system generates hyperplanes during a training stage to separate the classes and correctly classify unknown patterns in classification mode. A feature selector in the system reduces a large number of features to a smaller optimal set, maximizing performance and minimizing computation.

Fuller, Chris R.; Obrien, Walter F.; Cabell, Randolph H.

1988-01-01

300

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

SciTech Connect

Dynamical systems methods have been used to study bifurcations and pattern formation in nonequilibrium systems. Accomplishments during this period include: information-theoretic methods for analyzing chaos, chemical reactors for studying sustained reaction-diffusion patterns, a reactor exploiting pattern formation to extract short- lived intermediate species, observation of bifurcation from periodic to quasiperiodic rotating chemical spiral patterns, observation of a Turing bifurcation (transition from uniform state to a stationary chemical pattern), method for extracting noise strength in ramped convection, self-similar fractal structure of Zn clusters in electrodeposition, and dynamical instability in crack propagation.

Not Available

1992-12-31

301

Temporal Patterns of Anxious and Depressed Mood in Generalized Anxiety Disorder: A Daily Diary Study  

PubMed Central

Research suggests that anxiety disorders tend to temporally precede depressive disorders, a finding potentially relevant to understanding comorbidity. The current study used diary methods to determine whether daily anxious mood also temporally precedes daily depressed mood. 55 participants with generalized anxiety disorder (GAD) and history of depressive symptoms completed a 21-day daily diary tracking anxious and depressed mood. Daily anxious and depressed moods were concurrently associated. Daily anxious mood predicted later depressed mood at a variety of time lags, with significance peaking at a two-day lag. Depressed mood generally did not predict later anxious mood. Results suggest that the temporal antecedence of anxiety over depression extends to daily symptoms in GAD. Implications for the refinement of comorbidity models, including causal theories, are discussed. PMID:22196213

Starr, Lisa R.; Davila, Joanne

2011-01-01

302

Spatial and temporal patterns of endocrine active chemicals in small streams indicate differential exposure to aquatic organisms  

USGS Publications Warehouse

Alkylphenolic chemicals (APCs) and hormones were measured six times from February through October 2007 in three Minnesota streams receiving wastewater to identify spatial and temporal patterns in concentrations and in estrogen equivalency. Fish were collected once during the study to evaluate endpoints indicative of endocrine disruption. The most commonly detected APCs were 4-tert-octylphenol and 4-nonylphenol and the most commonly detected hormones were estrone and androstenedione. Chemical concentrations were greatest for nonylphenol ethoxycarboxylates (NPECs) (5,000-140,000 ng/l), followed by 4-nonlylphenol and 4-nonylphenolethoxylates (50-880 ng/l), 4-tert-octylphenol and 4-tert-octylphenolethoxylates with concentrations as great as 130 ng/l, and hormones (0.1-54 ng/l). Patterns in chemicals and estrogen equivalency indicated that wastewater effluent is a pathway of APCs and hormones to downstream locations in this study. However, upstream contributions can be equally or more important indicating alternative sources. This study indicates that aquatic organisms experience both spatially and temporally variable exposures in the number of compounds, total concentrations, and estrogenicity. This variability was evident in fish collected from the three rivers as no clear upstream to downstream pattern of endocrine disruption endpoints emerged.

Lee, K.E.; Barber, L.B.; Schoenfuss, H.L.

2014-01-01

303

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

NASA Astrophysics Data System (ADS)

The presence of low-lying stratocumulus clouds and fog has been known to modify biophysical and ecological properties in a variety of ecosystems in different climates. This is especially true for California's Channel Islands, where forests are frequently shaded by low-lying clouds or immersed in fog during warm and dry summer months. Previous studies suggest that clouds strongly modulate forest distributions as well as carbon and water budgets in these semi-arid environments by reducing solar insolation and raising relative humidity and thus reducing evapotranspiration, while also potentially supplying water directly to the landscape from fog-drip. While summertime fog and stratus cover in California's Channel Islands can ameliorate summer drought stress and enhance soil water budgets, they often have different spatial and temporal patterns. These differing patterns and the resulting shifts in relative ecological importance of fog and stratus are understudied. The overall objective of this study is to map spatial and temporal distributions of daytime cloud cover frequency for the California Channel Islands, and to predict probabilities of surface cloud (fog) contact and immersion for these islands. The results of this research are significant for water balance modeling, help explain vegetation patterns on the islands, and better identify locations where native vegetation restoration efforts are likely to be most successful.

Rastogi, Bharat

304

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

PubMed Central

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

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

2014-01-01

305

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

NASA Astrophysics Data System (ADS)

Non-point source pollution is the dominant pathway of nitrogen (N) transport in agriculture as well as urban watersheds. Very little is known about N transport in urban watersheds located in the subtropics. Our objective was to evaluate the spatial and temporal evolution patterns of N forms in streams draining sub-basins, ranging in size from 19 to 350 km2, of an urban watershed located in the Tampa Bay region. We used long-term monthly (1991-2009) and weekly (2009) stream water N concentration data collected from these sub-basins to evaluate the impact of urban development on N transport. Sub-basins were separated in two groups based on urban land uses: developed (18-24% residential, 1-14% built up) and undeveloped (3-11% residential, 1-3% built up). Mean monthly total N concentrations during 1991-2009 were 0.8-2.4 mg L-1 at all sites and were greatest in streams draining developed (1.7-2.4 mg L-1) than undeveloped (0.8-1.2 mg L-1) sub-basins. All the developed and undeveloped sub-basins had a narrow range of organic N concentration (0.60-0.77 mg L-1) in streams; however, percent organic N was about twice as much in streams draining undeveloped (66-71% of total N) than developed (30-44% of total N) sub-basins. On the other hand, both NO3-N concentration and percentage of total N were much greater in developed (0.89-1.66 mg L-1; 53-68% of total N) than undeveloped (0.21-0.37 mg L-1; 25-30% of total N) sub-basins. Among all N forms, mean monthly concentrations of NH4-N were lowest (<0.1 mg L-1; 2-5% of total N). Compared with long-term monthly total N concentrations, weekly total N concentrations were much higher (1.90-2.90 mg L-1) during 2009 high-flow period (June to September), with greater concentrations in developed (2.40-2.95 mg L-1) as compared to undeveloped (1.90-2.06 mg L-1) sub-basins. Concentrations of organic N mirrored a similar trend as total N at all sites. The weekly inorganic N (NO3-N, NH4-N) trends were similar to long-term data, with greater proportions in developed (26-39% of total N) than undeveloped (13-23% of total N) sub-basins. Percent weekly organic N was much greater (65-85% of total N) across all sites as compared to 1991-2009 monthly data (30-71% of total N). Organic N approached 77-85% of total N in undeveloped and 71-75% of total N in developed sub-basins. Organic N forms consists of dissolved organic N (DON; humic substances, amino acids, amino sugars, and tannins) and particulate organic N (PON; partially decomposed organic matter); these forms were measured in weekly samples. The undeveloped sub-basins had much greater concentrations of DON (0.97-1.05 mg L-1, 50-53% of total N) as compared to PON (0.56-0.64 mg L-1, 27-34% of total N). The transport of a specific organic N form whether DON or PON will be determined by the duration and intensity of rainfall-runoff events. For example, high-rainfall events may transport leaf litter and organic matter (that are components of PON) to streams, whereas low-rainfall events may not have enough hydrologic power to transport particulates from land to streams but can mobilize and carry DON to streams.

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

2010-12-01

306

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

PubMed

Measurements of the transmit beam patterns emitted by echolocating bats have previously been limited to cross-sectional planes or averaged over multiple signals using sparse microphone arrays. To date, no high-resolution measurements of individual bat transmit beams have been reported in the literature. Recent studies indicate that bats may change the time-frequency structure of their calls depending on the task, and suggest that their beam patterns are more dynamic than previously thought. To investigate beam pattern dynamics in a variety of bat species, a high-density reconfigurable microphone array was designed and constructed using low-cost ultrasonic microphones and custom electronic circuitry. The planar array is 1.83?m wide by 1.42?m tall with microphones positioned on a 2.54?cm square grid. The system can capture up to 228 channels simultaneously at a 500?kHz sampling rate. Beam patterns are reconstructed in azimuth, elevation, and frequency for visualization and further analysis. Validation of the array measurement system and post-processing functions is shown by reconstructing the beam pattern of a transducer with a fixed circular aperture and comparing the result with a theoretical model. To demonstrate the system in use, transmit beam patterns of the big brown bat, Eptesicus fuscus, are shown. PMID:24437791

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

2014-01-01

307

Temporal evolution of the chemical structure during the pattern transfer by ion-beam sputtering  

NASA Astrophysics Data System (ADS)

Ru films patterned by ion-beam sputtering (IBS) serve as sacrificial masks for the transfer of the patterns to Si(1 0 0) and metallic glass substrates by continued IBS. Under the same sputter condition, however, both bare substrates remain featureless. Chemical analyses of the individual nano structures simultaneously with the investigation of their morphological evolution reveal that the pattern transfer, despite its apparent success, suffers from premature degradation before the mask is fully removed by IBS. Moreover, the residue of the mask or Ru atoms stubbornly remains near the surface, resulting in unintended doping or alloying of both patterned substrates.

Ha, N.-B.; Jeong, S.; Yu, S.; Ihm, H.-I.; Kim, J.-S.

2015-01-01

308

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

Microsoft Academic Search

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

Leakha M. Henry; Brett A. Bryan

2000-01-01

309

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

Microsoft Academic Search

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

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

2009-01-01

310

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 ...

311

Temporal patterns of orchid mycorrhizal fungi in meadows and forests as revealed by 454 pyrosequencing.  

PubMed

Orchid mycorrhizal (OrM) symbionts play a key role in the growth of orchids, but the temporal variation and habitat partitioning of these fungi in roots and soil remain unclear. Temporal changes in root and rhizosphere fungal communities of Cypripedium calceolus, Neottia ovata and Orchis militaris were studied in meadow and forest habitats over the vegetation period by using 454 pyrosequencing of the full internal transcribed spacer (ITS) region. The community of typical OrM symbionts differed by plant species and habitats. The root fungal community of N. ovata changed significantly in time, but this was not observed in C. calceolus and O. militaris. The rhizosphere community included a low proportion of OrM symbionts that exhibited a slight temporal turnover in meadow habitats but not in forests. Habitat differences in OrM and all fungal associates are largely attributable to the greater proportion of ectomycorrhizal fungi in forests. Temporal changes in OrM fungal communities in roots of certain species indicate selection of suitable fungal species by plants. It remains to be elucidated whether these shifts depend on functional differences inside roots, seasonality, climate or succession. PMID:25546739

Oja, Jane; Kohout, Petr; Tedersoo, Leho; Kull, Tiiu; Kõljalg, Urmas

2015-03-01

312

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

313

Autobiographical Memory and Patterns of Brain Atrophy in Fronto-temporal Lobar Degeneration  

Microsoft Academic Search

Autobiographical memory paradigms have been increasingly used to study the behavioral and neuroanatomical correlates of human remote memory. Although there are numerous functional neuroimaging studies on this topic, relatively few studies of patient samples exist, with heterogeneity of results owing to methodological variability. In this study, fronto-temporal lobar degeneration (FTLD), a form of dementia affecting regions crucial to autobiographical memory,

Margaret C. Mckinnon; Elena I. Nica; Pheth Sengdy; Natasa Kovacevic; Morris Moscovitch; Morris Freedman; Bruce L. Miller; Sandra E. Black; Brian Levine

2008-01-01

314

Patterns of Autobiographical Memory Loss in Medial-Temporal Lobe Amnesic Patients  

Microsoft Academic Search

The issue of whether the hippocampus and related struc- tures in the medial-temporal lobe (MTL) play a temporary or permanent role in autobiographical episodic memory remains unresolved. One long-standing belief is that autobiographical memory (AM), like semantic memory, is initially dependent on the MTL but ultimately can be retained and recovered independently of it. However, evidence that hippocampal amnesia results

R. Shayna Rosenbaum; Morris Moscovitch; Jonathan K. Foster; David M. Schnyer; Fuqiang Gao; Natasha Kovacevic; Mieke Verfaellie; Sandra E. Black; Brian Levine

2008-01-01

315

Temporal logic patterns for querying dynamic models of cellular interaction networks  

Microsoft Academic Search

Motivation: Models of the dynamics of cellular interaction networks have become increasingly larger in recent years. Formal verification based on model checking provides a powerful technology to keep up with this increase in scale and complexity. The application of model- checking approaches is hampered, however, by the difficulty for non- expert users to formulate appropriate questions in temporal logic. Results:

Pedro T. Monteiro; Delphine Ropers; Radu Mateescu; Ana T. Freitas; Hidde De Jong

2008-01-01

316

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

Microsoft Academic Search

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

Jerry H. Ratcliffe

2002-01-01

317

Temporal scales of auditory objects underlying birdsong vocal recognition  

PubMed Central

Vocal recognition is common among songbirds, and provides an excellent model system to study the perceptual and neurobiological mechanisms for processing natural vocal communication signals. Male European starlings, a species of songbird, learn to recognize the songs of multiple conspecific males by attending to stereotyped acoustic patterns, and these learned patterns elicit selective neuronal responses in auditory forebrain neurons. The present study investigates the perceptual grouping of spectrotemporal acoustic patterns in starling song at multiple temporal scales. The results show that permutations in sequencing of submotif acoustic features have significant effects on song recognition, and that these effects are specific to songs that comprise learned motifs. The observations suggest that (1) motifs form auditory objects embedded in a hierarchy of acoustic patterns, (2) that object-based song perception emerges without explicit reinforcement, and (3) that multiple temporal scales within the acoustic pattern hierarchy convey information about the individual identity of the singer. The authors discuss the results in the context of auditory object formation and talker recognition. PMID:18681620

Gentner, Timothy Q.

2008-01-01

318

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

319

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

Microsoft Academic Search

Seed predation is an important factor in determining the rate of tree establishment in abandoned agricultural land. Edges, through altered habitat use by small mammals, may influence the spatial pattern of forest regeneration in these successional sites. To determine the spatial pattern of seed predation across a forest-old field edge, we used a grid that began 30 m inside the

Scott J. Meiners; Kathleen LoGiudice

2003-01-01

320

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

Microsoft Academic Search

Seed predation is an important factor in determining the rate of tree establishment in abandoned agricultural land. Edges, through altered habitat use by small mammals, may influence the spatial pattern of forest regenera- tion in these successional sites. To determine the spatial pattern of seed predation across a forest-old field edge, we used a grid that began 30 m inside

Scott J. Meiners; Kathleen LoGiudice

2003-01-01

321

Model of cellular and network mechanisms for odor-evoked temporal patterning in the locust antennal lobe.  

PubMed

Locust antennal lobe (AL) projection neurons (PNs) respond to olfactory stimuli with sequences of depolarizing and hyperpolarizing epochs, each lasting hundreds of milliseconds. A computer simulation of an AL network was used to test the hypothesis that slow inhibitory connections between local neurons (LNs) and PNs are responsible for temporal patterning. Activation of slow inhibitory receptors on PNs by the same GABAergic synapses that underlie fast oscillatory synchronization of PNs was sufficient to shape slow response modulations. This slow stimulus- and neuron-specific patterning of AL activity was resistant to blockade of fast inhibition. Fast and slow inhibitory mechanisms at synapses between LNs and PNs can thus form dynamical PN assemblies whose elements synchronize transiently and oscillate collectively, as observed not only in the locust AL, but also in the vertebrate olfactory bulb. PMID:11395015

Bazhenov, M; Stopfer, M; Rabinovich, M; Abarbanel, H D; Sejnowski, T J; Laurent, G

2001-05-01

322

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

NASA Astrophysics Data System (ADS)

Temporal and spatial patterns of recruitment ( R) and spawning stock biomass ( S) variability were compared among functionally analogous species and similar feeding guilds from six marine ecosystems. Data were aggregated into four regions including the Gulf of Maine/Georges Bank, the Norwegian/Barents Seas, the eastern Bering Sea, and the Gulf of Alaska. Variability was characterized by calculating coefficients of variation and anomalies for three response variables: ln( R), ln( R/ S), and stock-recruit model residuals. Patterns of synchrony and asynchrony in the response variables were examined among and between ecosystems, between- and within-ocean basins and among functionally analogous species groups using pair-wise correlation analysis corrected for within-time series autocorrelation, multivariate cross-correlation analyses and regime shift detectors. Time series trends in response variables showed consistent within basin similarities and consistent and coherent differences between the Atlantic and Pacific basin ecosystems. Regime shift detection algorithms identified two broad-scale regime shift time periods for the pelagic feeding guild (1972-1976 and 1999-2002) and possibly one for the benthic feeding guild (1999-2002). No spatial patterns in response variable coefficients of variation were observed. Results from multivariate cross-correlation analysis showed similar trends. The data suggest common external factors act in synchrony on stocks within ocean basins but temporal stock patterns, often of the same species or functional group, between basins change in opposition to each other. Basin-scale results (similar within but different between) suggest that the two geographically broad areas are connected by unknown mechanisms that, depending on the year, may influence the two basins in opposite ways. This work demonstrates that commonalities and synchronies in recruitment fluctuations can be found across geographically distant ecosystems but biophysical causes of the fluctuations remain difficult to identify.

Megrey, Bernard A.; Hare, Jonathan A.; Stockhausen, William T.; Dommasnes, Are; Gjøsæter, Harald; Overholtz, William; Gaichas, Sarah; Skaret, Georg; Falk-Petersen, Jannike; Link, Jason S.; Friedland, Kevin D.

2009-04-01

323

Complex temporal patterns in molecular dynamics: A direct measure of the phase-space exploration by the trajectory at macroscopic time scales  

E-print Network

Complex temporal patterns in molecular dynamics: A direct measure of the phase-space exploration how the trajectory explores the phase space and independent from the particular molecular signal used in liquids form complex patterns in the phase space. Because of the system's high dimensionality defined

Nerukh, Dmitry

324

Spatial and temporal patterns of cuttlefish (Sepia officinalis) abundance and environmental influences – a case study using trawl fishery data in French Atlantic coastal, English Channel, and adjacent waters  

Microsoft Academic Search

The spatial and temporal distribution patterns of cuttlefish abundance and the relationships between cuttlefish abundance and environmental variables in the French Atlantic coast, the English Channel, and adjacent waters were studied using both geographical information system and statistical methods. Cuttlefish have a clear general annual migration pattern, consistently occurring in broadly the same areas in different years. The strength of

Jianjun Wang; Graham J. Pierce; Peter R. Boyle; Vincent Denis; Jean-paul Robin; Jose M. Bellido

2003-01-01

325

Temporal Asthma Patterns Using Repeated Questionnaires over 13 Years in a Large French Cohort of Women  

PubMed Central

Variable expression is one aspect of the heterogeneity of asthma. We aimed to define a variable pattern, which is relevant in general health epidemiological cohorts. Our objectives were to assess whether: 1) asthma patterns defined using simple asthma questions through repeated measurements could reflect disease variability 2) these patterns may further be classified according to asthma severity/control. Among 70,428 French women, we used seven questionnaires (1992–2005) and a comprehensive reimbursement database (2004–2009) to define three reliable asthma patterns based on repeated positive answers to the ever asthma attack question: “never asthma” (n?=?64,061); “inconsistent” (“yes” followed by “no”, n?=?3,514); “consistent” (fully consistent positive answers, n?=?2,853). The “Inconsistent” pattern was related to both long-term (childhood-onset asthma with remission in adulthood) and short-term (reported asthma attack in the last 12 months, associated with asthma medication) asthma variability, showing that repeated questions are relevant markers of the variable expression of asthma. Furthermore, in this pattern, the number of positive responses (1992–2005) predicted asthma drug consumption in subsequent years, a marker of disease severity. The “Inconsistent” pattern is a phenotype that may capture the variable expression of asthma. Repeated answers, even to a simple question, are too often neglected. PMID:23741466

Sanchez, Margaux; Bousquet, Jean; Le Moual, Nicole; Jacquemin, Bénédicte; Clavel-Chapelon, Françoise; Humbert, Marc; Kauffmann, Francine; Tubert-Bitter, Pascale; Varraso, Raphaëlle

2013-01-01

326

Spatial and Temporal Patterns in Cimex lectularius (Hemiptera: Cimicidae) Reporting in Philadelphia, PA  

PubMed Central

We analyzed a comprehensive telephone log of pest infestation reports to assess the spatial and temporal trends in Cimex lectularius L. (bed bug) reporting throughout Philadelphia, PA. Citywide spatial analyses of reports from September 2011 to June 2012 revealed several statistically significant bed bug hotspots. However, these were small and diffuse. Temporal analyses of reports from December 2008 to May 2011 detected prominent seasonality in bed bug reporting, peaking in August and reaching a nadir in February each year. Controlling for seasonal cycling, the number of bed bug reports in Philadelphia increased steadily at a rate of ?4.5% per month (or 69.45% per year) from December 2008 to May 2011. While it may be difficult to spatially target citywide bed bug control measures because of the insects’ widespread migration, interventions informed by seasonal trends may enhance efforts to curb the recent increases in urban bed bug populations. PMID:24605452

MABUD, TARUB S.; BARBARIN, ALEXIS M.; BARBU, CORENTIN M.; LEVY, KATELYN H.; EDINGER, JASON; LEVY, MICHAEL Z.

2014-01-01

327

GET MOVE: An Efficient and Unifying Spatio-Temporal Pattern Mining Algorithm for Moving Objects  

E-print Network

whenever new data are added to the existing database. To address these issues, we first redefine spatio for real world applications. Telemetry attached on wildlife, GPS installed in cars, sensor networks-Temporal Database Objects ODB Timesets TDB x y o1 t1 2.3 1.2 o2 t1 2.1 1 o1 t2 10.3 28.1 To extract these kinds

Boyer, Edmond

328

Macrophyte assemblage associated with an invasive species exhibiting temporal variability in its development pattern  

Microsoft Academic Search

Many invasive species show temporal variations in abundances, such as seasonal cycles and medium to long term variations.\\u000a The effects of invasive species on native assemblages have, however, mainly been investigated during the maximum abundance\\u000a of the invasive species and rarely over an entire year. At the north-western limit of its distribution range in the Mediterranean\\u000a Sea, the invasive marine

Judith C. Klein; Marc Verlaque

2009-01-01

329

Spatial Patterns and Temporal Trajectories of the Bog Ground Layer Along a Post-Fire Chronosequence  

Microsoft Academic Search

Peatland ground layer species composition is intricately tied to ecosystem function (for example, carbon storage). As the\\u000a primary disturbance in boreal bogs, wildfire selectively removes the ground layer vegetation, creating heterogeneous habitat\\u000a conditions and initiating succession. However, the successional trajectory of the ground layer community following fire is\\u000a poorly understood. Here we assess spatial and temporal changes in community composition

Brian W. Benscoter; Dale H. Vitt

2008-01-01

330

Temporal Processing of Brain Activity for the Recognition of EEG Patterns  

Microsoft Academic Search

This paper discusses three common strategies to incorporate temporal dynamics of brain activity to recognize 3 mental tasks\\u000a from spontaneous EEG signals. The networks have been tested in a hard experimental setup; namely, generalization over different\\u000a recording sessions while analyzing short time windows. It turns out that the simple local neural classifier currently embedded\\u000a in our BCI, which averages the

Alexandre Hauser; Pierre-edouard Sottas; José Del R. Millán

2002-01-01

331

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

Microsoft Academic Search

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

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

2008-01-01

332

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 PMID:2062830

Wallrath, L L; Friedman, T B

1991-01-01

333

Space-based constraints on spatial and temporal patterns of NO(x) emissions in California, 2005-2008.  

PubMed

We describe ground and space-based measurements of spatial and temporal variation of NO(2) in four California metropolitan regions. The measurements of weekly cycles and trends over the years 2005-2008 observed both from the surface and from space are nearly identical to each other. Observed decreases in Los Angeles and the surrounding cities are 46% on weekends and 9%/year from 2005-2008. Similar decreases are observed in the San Francisco Bay area and in Sacramento. In the San Joaquin Valley cities of Fresno and Bakersfield weekend decreases are much smaller, only 27%, and the decreasing trend is only 4%/year. We describe evidence that the satellite observations provide a uniquely complete view of changes in spatial patterns over time. For example, we observe variations in the spatial pattern of weekday-weekend concentrations in the Los Angeles basin with much steeper weekend decreases at the eastern edge of the basin. We also observe that the spatial extent of high NO(2) in the San Joaquin Valley has not receded as much as it has for other regions in the state. Analysis of these measurements is used to describe observational constraints on temporal trends in emission sources in the different regions. PMID:20364869

Russell, Ashley R; Valin, Lukas C; Bucsela, Eric J; Wenig, Mark O; Cohen, Ronald C

2010-05-01

334

Theoretical calculation of the acoustic force on a patterned silicon wafer during megasonic cleaning  

E-print Network

circuits prior to packaging, namely a micron-size silicon ridge and a metal wire tens to hundreds. S0021-8979 00 03017-6 I. INTRODUCTION Megasonic waves have been extensively used to remove patterned wafers for instance vias clean- ing with megasonic waves. However, little is known about

Deymier, Pierre

335

High-Resolution Temporal Response Patterns to Influenza Vaccine Reveal a Distinct Human Plasma Cell Gene Signature  

PubMed Central

To identify sources of inter-subject variation in vaccine responses, we performed high-frequency sampling of human peripheral blood cells post-vaccination, followed by a novel systems biology analysis. Functional principal component analysis was used to examine time varying B cell vaccine responses. In subjects vaccinated within the previous three years, 90% of transcriptome variation was explained by a single subject-specific mathematical pattern. Within individual vaccine response patterns, a common subset of 742 genes was strongly correlated with migrating plasma cells. Of these, 366 genes were associated with human plasmablasts differentiating in vitro. Additionally, subject-specific temporal transcriptome patterns in peripheral blood mononuclear cells identified migration of myeloid/dendritic cell lineage cells one day after vaccination. Upstream analyses of transcriptome changes suggested both shared and subject-specific transcription groups underlying larger patterns. With robust statistical methods, time-varying response characteristics of individual subjects were effectively captured along with a shared plasma cell gene signature. PMID:23900141

Henn, Alicia D.; Wu, Shuang; Qiu, Xing; Ruda, Melissa; Stover, Michael; Yang, Hongmei; Liu, Zhiping; Welle, Stephen L.; Holden-Wiltse, Jeanne; Wu, Hulin; Zand, Martin S.

2013-01-01

336

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

Microsoft Academic Search

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

Magdalena ?ywiec; Mateusz Ledwo?

2008-01-01

337

Temporal Masking in Electric Hearing  

PubMed Central

Temporal masking can be defined as the detection threshold of a brief signal as a function of the signal delay in a relatively long masker. The temporal masking pattern in normal acoustic hearing reveals temporal edge enhancement in which the signal detection threshold is greater near the masker onset than in the steady-state portion. Both peripheral and central mechanisms appear to underlie temporal edge enhancement, but their relative contributions remain elusive. Cochlear implants bypass cochlear mechanical processing and stimulate the auditory nerve directly, thereby providing a unique opportunity to separate the peripheral mechanisms from the central mechanisms. Here, we systematically measured temporal masking in electric hearing by examining whether a brief signal was harder to detect at the onset than in the steady-state portion of a long masker (the “overshoot” effect). The signal and the masker were presented (1) either to the same electrode or to different electrodes, (2) at the same stimulation or different rates, and (3) in a simultaneous or an interleaved fashion. A consistent pattern of results was observed, depending on the stimulus configuration between the signal and the masker. Simultaneous stimulation at the same rate and with the same electrode produced no difference in sensitivity between the onset and the steady-state conditions, but interleaved stimulation at different rates or with different electrodes produced a significant difference. Unlike acoustic hearing, high masker levels produced an overshoot effect, and low masker levels produced an undershoot effect. Although the present results are consistent with the “on-frequency vs. off-frequency” hypothesis for the overshoot effect, results also suggest a central “same vs. different” mechanism underlying temporal masking. These results have practical implications for improving cochlear implant design. PMID:16261267

Chen, Hongbin; Han, Shilong

2005-01-01

338

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

PubMed Central

In research, it has been difficult to characterize the prosodic production differences that have been observed clinically in Autism Spectrum Disorders (ASD). Moreover, the nature of these differences has been particularly hard to identify. This study examined one possible contributor to these perceived differences: motor planning. We examined the ability of children and adolescents with ASD to imitate prosodic patterns in comparison to a group with learning disabilities (LD) and a typically-developing (TD) comparison group. Overall, we found that both the ASD and LD groups were significantly worse at perceiving and imitating prosodic patterns than the TD comparison group. Similar to previous studies using non-imitative speech, participants with ASD showed a significantly longer duration of utterances than the two comparison groups when attempting to imitate an intonation pattern. The implications of differences in duration of utterances are discussed. This study also highlights the importance of using clinical comparison groups in studies of language performance in individuals with ASD. PMID:22125576

Diehl, Joshua John; Paul, Rhea

2011-01-01

339

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

PubMed Central

Background The relationship between entomological measures of malaria transmission intensity and mortality remains uncertain. This is partly because transmission is heterogeneous even within small geographical areas. Studying this relationship requires high resolution, spatially structured, longitudinal entomological data. Geostatistical models that have been used to analyse the spatio-temporal heterogeneity have not considered the uncertainty in both sporozoite rate (SR) and mosquito density data. This study analysed data from Kassena-Nankana districts in northern Ghana to obtain small area estimates of malaria transmission rates allowing for this uncertainty. Methods Independent Bayesian geostatistical models for sporozoite rate and mosquito density were fitted to produce explicit entomological inoculation rate (EIR) estimates for small areas and short time periods, controlling for environmental factors. Results Mosquitoes were trapped from 2,803 unique locations for three years using mainly CDC light traps. Anopheles gambiae constituted 52%, the rest were Anopheles funestus. Mean biting rates for An. funestus and An. gambiae were 32 and 33 respectively. Most bites occurred in September, the wettest month. The sporozoite rates were higher in the dry periods of the last two years compared with the wet period. The annual EIR varied from 1,132 to 157 infective bites. Monthly EIR varied between zero and 388 infective bites. Spatial correlation for SR was lower than that of mosquito densities. Conclusion This study confirms the presence of spatio-temporal heterogeneity in malaria transmission within a small geographical area. Spatial variance was stronger than temporal especially in the SR. The estimated EIR will be used in mortality analysis for the area. PMID:23405912

2013-01-01

340

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 km 2 in the Sakurakigawa watershed representing 35% of the watershed area. Similarly slides denuded a total of 0.534 km 2 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

341

Temporal and Spatial Expression Patterns of miR-302 and miR-367 During Early Embryonic Chick Development  

PubMed Central

The microRNAs (miRNAs) are small, non-coding RNAs that modulate protein expression by interfering with target mRNA translation or stability. miRNAs play crucial roles in various functions such as cellular, developmental, and physiological processes. The spatial expression patterns of miRNAs are very essential for identifying their functions. The expressions of miR-302 and miR-367 are critical in maintaining stemness of pluripotent stem cells, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) but their functions in early development are not fully elucidated. So, we used Locked Nucleic Acid (LNA) probes to perform in situ hybridization and confirmed the temporal and spatial distribution patterns during early chick development. As a result, we found that miR-302 and miR-367 were expressed in various tissues such as primitive steak, neural ectoderm, neural plate, neural fold, neural tube, notochord, and oral cavity. Specially, we confirmed that miR-302 and miR-367 were strongly expressed in neural folds in HH8 to HH10. miR-302 was expressed on dorsal part of the neural tube but miR-367 was expressed on lateral and ventral parts of the neural tube. And also we performed quantitative stem-loop real-time PCR to analyze global expression level of miR-302 and miR-367. miR-302 and miR-367 expression was sustained before Hamburger and Hamilton stage (HH) 14. Thus, the temporal and spatial expression patterns of miR-302 and miR-367 may provide us information of the role of these miRNAs on tissue formation during early chick development. PMID:25473455

Jeong, Hoe-Su; Lee, Jong-Min; Suresh, Bharathi; Cho, Kyong-Won; Jung, Han-Sung; Kim, Kye-Seong

2014-01-01

342

Temporal and Spatial Expression Patterns of miR-302 and miR-367 During Early Embryonic Chick Development.  

PubMed

The microRNAs (miRNAs) are small, non-coding RNAs that modulate protein expression by interfering with target mRNA translation or stability. miRNAs play crucial roles in various functions such as cellular, developmental, and physiological processes. The spatial expression patterns of miRNAs are very essential for identifying their functions. The expressions of miR-302 and miR-367 are critical in maintaining stemness of pluripotent stem cells, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) but their functions in early development are not fully elucidated. So, we used Locked Nucleic Acid (LNA) probes to perform in situ hybridization and confirmed the temporal and spatial distribution patterns during early chick development. As a result, we found that miR-302 and miR-367 were expressed in various tissues such as primitive steak, neural ectoderm, neural plate, neural fold, neural tube, notochord, and oral cavity. Specially, we confirmed that miR-302 and miR-367 were strongly expressed in neural folds in HH8 to HH10. miR-302 was expressed on dorsal part of the neural tube but miR-367 was expressed on lateral and ventral parts of the neural tube. And also we performed quantitative stem-loop real-time PCR to analyze global expression level of miR-302 and miR-367. miR-302 and miR-367 expression was sustained before Hamburger and Hamilton stage (HH) 14. Thus, the temporal and spatial expression patterns of miR-302 and miR-367 may provide us information of the role of these miRNAs on tissue formation during early chick development. PMID:25473455

Jeong, Hoe-Su; Lee, Jong-Min; Suresh, Bharathi; Cho, Kyong-Won; Jung, Han-Sung; Kim, Kye-Seong

2014-11-01

343

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

NASA Technical Reports Server (NTRS)

Counts of taxonomic diversity are the prevailing standards for documenting large-scale patterns of evolution in the fossil record. However, the secular pattern of relative ecological importance between the bryozoan clades Cyclostomata and Cheilostomata is not reflected fully in compilations of generic diversity or within-fauna species richness, and the delayed ecological recovery of the Cheilostomata after the mass extinction at the Cretaceous-Tertiary boundary is missed entirely. These observations demonstrate that evolutionary success and ecological dominance can be decoupled and profoundly different, even over tens of millions of years.

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

1998-01-01

344

Temporal patterns of diversification and microendemism in Eastern Highland endemic barcheek darters (Percidae: Etheostomatinae).  

PubMed

Eastern North America is the location of the world's most species-rich temperate freshwater fish fauna. Hypotheses regarding the geographic and temporal scale of teleost diversification in this region have not been broadly investigated using absolute divergence time estimates among the constituent lineages. This study used time-calibrated molecular phylogenies estimated from mitochondrial and nuclear genes to investigate the temporal and geographic signatures of diversification within barcheek darters, a clade of allopatrically distributed species endemic to the Eastern Highlands. Results from divergence time estimates using an uncorrelated lognormal model suggest that the barcheek darters are an ancient group with a crown node estimate of 16.3 mya, 95% highest posterior density (HPD): [12.4, 20.5], and the clade is characterized by substantial intraspecific divergence times within several species. In particular, the Caney Fork endemic Etheostoma basilare comprises five strongly supported and deeply divergent clades with a most recent common ancestor estimated at 8.0 mya, 95% HPD: [5.6, 10.7]. These results are concordant with the hypothesis that geologically stable areas of eastern North America have facilitated both the generation and preservation of lineages across a substantial breadth of evolutionary time, and that allopatric speciation in darters has occurred at much smaller spatial scales than previously realized. PMID:18826450

Hollingsworth, Phillip R; Near, Thomas J

2009-01-01

345

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

2008-11-01

346

Acquisition of an acoustic template leads to refinement of song motor gestures.  

PubMed

Vocal learning, a key behavior in human speech development, occurs only in a small number of animal taxa. Ontogeny of vocal behavior in humans and songbirds involves acquisition of an acoustic model, which guides the development of self-generated vocalizations (sensorimotor period). How vocal development proceeds in the absence of an acoustic model is largely unknown and cannot be studied directly in humans. Here we explored the effects of an acoustic model on song motor control by comparing peripheral motor gestures (respiration and syringeal muscles) of tutored birds with those of birds raised in acoustic isolation. Although the overall use of syringeal muscles during song was similar in both groups, tutored birds displayed enhanced temporal patterns of activation in respiratory and syringeal motor gestures. Muscle activation was more uniformly distributed throughout the song of tutored birds than that of untutored birds. Similarly, the respiratory effort was similar for both groups, but the expiratory pulses of song contained more modulations and temporal complexity in tutored birds. These results indicate that the acquisition of an acoustic template guides a refinement of experience-independent motor gestures by increasing temporal fine structure, but there is no difference in bilateral activation patterns for a given sound between the two groups. Nevertheless, these subtle temporal changes in muscle activation give rise to pronounced acoustic differences between the songs of the tutored and untutored birds. Experience with song during ontogeny therefore guides a more refined use of experience-independent motor programs. PMID:20554848

Méndez, Jorge M; Dall'Asén, Analía G; Cooper, Brenton G; Goller, Franz

2010-08-01

347

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

PubMed Central

Background Climate change can affect the activity and distribution of species, including pathogens and parasites. The densities and distribution range of the sheep tick (Ixodes ricinus) and it’s transmitted pathogens appears to be increasing. Thus, a better understanding of questing tick densities in relation to climate and weather conditions is urgently needed. The aim of this study was to test predictions regarding the temporal pattern of questing tick densities at two different elevations in Norway. We predict that questing tick densities will decrease with increasing elevations and increase with increasing temperatures, but predict that humidity levels will rarely affect ticks in this northern, coastal climate with high humidity. Methods We described the temporal pattern of questing tick densities at ~100 and ~400 m a.s.l. along twelve transects in the coastal region of Norway. We used the cloth lure method at 14-day intervals during the snow-free season to count ticks in two consecutive years in 20 m2 plots. We linked the temporal pattern of questing tick densities to local measurements of the prevailing weather. Results The questing tick densities were much higher and the season was longer at ~100 compared to at ~400 m a.s.l. There was a prominent spring peak in both years and a smaller autumn peak in one year at ~100 m a.s.l.; but no marked peak at ~400 m a.s.l. Tick densities correlated positively with temperature, from low densities <5°C, then increasing and levelling off >15-17°C. We found no evidence for reduced questing densities during the driest conditions measured. Conclusions Tick questing densities differed even locally linked to elevation (on the same hillside, a few kilometers apart). The tick densities were strongly hampered by low temperatures that limited the duration of the questing seasons, whereas the humidity appeared not to be a limiting factor under the humid conditions at our study site. We expect rising global temperatures to increase tick densities and lead to a transition from a short questing season with low densities in the current cold and sub-optimal tick habitats, to longer questing seasons with overall higher densities and a marked spring peak. PMID:24725997

2014-01-01

348

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...

349

Temporal patterns of vascular plant diversity in southeastern New Hampshire forests  

Microsoft Academic Search

A chronosequence of 22 sites in Durham, NH, was used to study upland successional patterns of species diversity over a span of 14–209 years of forest development and to test the hypothesis that diversity is maximized at mid-succession. Nested quadrat sampling was used to estimate the relative importance values of vascular plant species in the tree, shrub, and herb strata.

Lauren F. Howard; Thomas D. Lee

2003-01-01

350

On Determination of Minimum Sample Size for Discovery of Temporal Gene Expression Patterns  

Microsoft Academic Search

DNA microarray technologies allow for the simultaneous monitoring of thousands of genes, which reveal important information about cellular and tissue expression phenotypes. From a viewpoint of data analysis, microarray experiments may be classified into (1) classification of patients or non-patients or more subtypes in terms of gene expressions, (2) discovery of gene expression patterns over a set of different conditions,

Fang-xiang Wu; W. J. Zhang; Anthony J. Kusalik

2006-01-01

351

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

E-print Network

injuries, and Levy et al. [10] studied the #12;long term effects of Alzheimer's disease. The application of "consultations" are available. For example Yamaguchi et al. ([18]) studied the effect of treatments for shoulder: the TFP algorithm [2, 3] is used in this study, however alternative frequent pattern miners could

Coenen, Frans

352

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

ERIC Educational Resources Information Center

Two studies investigated the effectiveness of dynamic and static visualizations for a perceptual learning task (locomotion pattern classification). In Study 1, seventy-five students viewed either dynamic, static-sequential, or static-simultaneous visualizations. For tasks of intermediate difficulty, dynamic visualizations led to better…

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

2012-01-01

353

Global Climate Patterns to Model the Spatial and Temporal Distribution of Vector-Borne Diseases  

Technology Transfer Automated Retrieval System (TEKTRAN)

Global climate patterns, such as the El Niño/Southern Oscillation (ENSO), have been shown to have an impact on vector-borne infectious disease outbreaks. In October 2006 the Climate Prediction Center of the National Oceanic and Atmospheric Administration (NOAA/CPC) issued an unscheduled El Niño advi...

354

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

355

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

356

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

NASA Astrophysics Data System (ADS)

It is of significant importance to investigate the spatial-temporal change in precipitation patterns due to its great effects on droughts, floods, soil erosion and water resource management. A complete investigation of precipitation structure and its distribution pattern based on daily precipitation covering 1960-2005 at 21 meteorological stations in the Wei River Basin has been performed. In order to comprehensively and objectively describe the changing pattern of precipitation, the cloud model is employed to quantitatively analyse the average, uniformity and stability of precipitation. Results indicate the following: (1) the occurrence of different precipitation durations exhibits a positive exponential curve with the decrease in precipitation durations, and 1-3-day events are the predominant precipitation events which have an increasing trend; (2) precipitation and its non-uniformity is increasingly reducing, while its stability increases initially then decreases; (3) mean precipitation reduces from southeast to northwest, and the precipitation of the Guanzhong Plain has a low uniformity and stability due to its location and increasingly intensifying human activities. The cloud model provides a new idea and quantitative measure for the evaluation of the uniformity and stability of precipitation.

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

2014-05-01

357

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

PubMed Central

Contemporary theories of the medial temporal lobe (MTL) suggest that there are functional differences between the MTL cortex and the hippocampus. High-resolution functional magnetic resonance imaging and multivariate pattern analysis were utilized to study whether MTL subregions could classify categories of images, with the hypothesis that the hippocampus would be less representationally categorical than the MTL cortex. Results revealed significant classification accuracy for faces versus objects and faces versus scenes in MTL cortical regions—parahippocampal cortex and perirhinal cortex—with little evidence for category discrimination in the hippocampus. MTL cortical regions showed significantly greater classification accuracy than the hippocampus. The hippocampus showed significant classification accuracy for images compared to a non-mnemonic baseline task, suggesting that it responded to the images. Classification accuracy in a region of interest encompassing retrosplenial cortex and the posterior cingulate cortex posterior to retrosplenial cortex (RSC/PCC), showed a similar pattern of results to parahippocampal cortex, supporting the hypothesis that these regions are functionally related. The results suggest that parahippocampal cortex, perirhinal cortex, and RSC/PCC are representationally categorical and the hippocampus is more representationally agnostic, which is concordant with the hypothesis of the role of the hippocampus in pattern separation. PMID:24976498

Huffman, Derek J.; Stark, Craig E.L.

2014-01-01

358

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

PubMed

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

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

2014-12-01

359

Spatio-temporal activity patterns of odor-induced synchronized potentials revealed by voltage-sensitive dye imaging and intracellular recording in the antennal lobe of the cockroach  

PubMed Central

In animals, odor qualities are represented as both spatial activity patterns of glomeruli and temporal patterns of synchronized oscillatory signals in the primary olfactory centers. By optical imaging of a voltage-sensitive dye (VSD) and intracellular recording from secondary olfactory interneurons, we examined possible neural correlates of the spatial and temporal odor representations in the primary olfactory center, the antennal lobe (AL), of the cockroach Periplaneta americana. Voltage-sensitive dye imaging revealed that all used odorants induced odor-specific temporal patterns of depolarizing potentials in specific combinations of anterior glomeruli of the AL. The depolarizing potentials evoked by different odorants were temporally synchronized across glomeruli and were termed “synchronized potentials.” These observations suggest that odor qualities are represented by spatio-temporal activity patterns of the synchronized potentials across glomeruli. We also performed intracellular recordings and stainings from secondary olfactory interneurons, namely projection neurons and local interneurons. We analyzed the temporal structures of enanthic acid-induced action potentials of secondary olfactory interneurons using simultaneous paired intracellular recording from two given neurons. Our results indicated that the multiple local interneurons synchronously fired in response to the olfactory stimulus. In addition, all stained enanthic acid-responsive projection neurons exhibited dendritic arborizations within the glomeruli where the synchronized potentials were evoked. Since multiple local interneurons are known to synapse to a projection neuron in each glomerulus in the cockroach AL, converging inputs from local interneurons to the projection neurons appear to contribute the odorant specific spatio-temporal activity patterns of the synchronized potentials. PMID:22848191

Watanabe, Hidehiro; Ai, Hiroyuki; Yokohari, Fumio

2012-01-01

360

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

PubMed

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

Burger, Joanna; Tsipoura, Nellie

2014-10-01

361

Temporal trends of perfluorooctanesulfonate isomer and enantiomer patterns in archived Swedish and American serum samples.  

PubMed

Human perfluorooctanesulfonate (PFOS) body burdens are attributable to both direct PFOS and indirect PFOS precursor (PreFOS) exposure. The relative importance of these two pathways has been estimated, but the relative temporal trajectory of exposure to PFOS and PreFOS has not been examined. Here, two hypothesized biomarkers of PreFOS exposure, PFOS isomer profiles (quantified as percent branched PFOS, %br-PFOS) and chiral 1m-PFOS enantiomer fractions (1m-PFOS EF) were analyzed in archived human serum samples of individual American adults (1974-2010) and pooled samples of Swedish primiparous women (1996-2010). After correcting for potential confounders, significant correlations between %br-PFOS and 1m-PFOS EFs were observed in American samples and in Swedish samples for the 1996-2000 period, supporting the hypothesis that both %br-PFOS and 1m-PFOS EF are biomarkers of PreFOS exposure. Significant trends of increasing %br-PFOS, from 2000 to 2010, and increasingly non-racemic 1m-PFOS EFs, from 1996 to 2000, were detected in Swedish samples. No statistically significant trend for %br-PFOS or 1m-PFOS EF was observed in American samples, but American males had significantly higher %br-PFOS and significantly lower 1m-PFOS EF (i.e. more non-racemic) than females, and a similar significant difference was shown in the older age group, relative to the younger age group. These temporal trends in %br-PFOS and 1m-PFOS EF are not easily explained and the results highlight uncertainties about how humans are exposed to PFOS. PMID:25490284

Liu, Yanna; Pereira, Alberto S; Beesoon, Sanjay; Vestergren, Robin; Berger, Urs; Olsen, Geary W; Glynn, Anders; Martin, Jonathan W

2015-02-01

362

Clinical and temporal patterns of severe pneumonia causing critical illness during Hajj  

PubMed Central

Background Pneumonia is a leading cause of hospitalization during Hajj and susceptibility and transmission may be exacerbated by extreme spatial and temporal crowding. We describe the number and temporal onset, co–morbidities, and outcomes of severe pneumonia causing critical illness among pilgrims. Method A cohort study of all critically ill Hajj patients, of over 40 nationalities, admitted to 15 hospitals in 2 cities in 2009 and 2010. Demographic, clinical, and laboratory data, and variables necessary for calculation of the Acute Physiology and Chronic Health Evaluation IV scores were collected. Results There were 452 patients (64.6% male) who developed critical illness. Pneumonia was the primary cause of critical illness in 123 (27.2%) of all intensive care unit (ICU) admissions during Hajj. Pneumonia was community (Hajj)–acquired in 66.7%, aspiration–related in 25.2%, nosocomial in 3.3%, and tuberculous in 4.9%. Pneumonia occurred most commonly in the second week of Hajj, 95 (77.2%) occurred between days 5–15 of Hajj, corresponding to the period of most extreme pilgrim density. Mechanical ventilation was performed in 69.1%. Median duration of ICU stay was 4 (interquartile range [IQR] 1–8) days and duration of ventilation 4 (IQR 3–6) days. Commonest preexisting co–morbidities included smoking (22.8%), diabetes (32.5%), and COPD (17.1%). Short–term mortality (during the 3–week period of Hajj) was 19.5%. Conclusion Pneumonia is a major cause of critical illness during Hajj and occurs amidst substantial crowding and pilgrim density. Increased efforts at prevention for at risk pilgrim prior to Hajj and further attention to spatial and physical crowding during Hajj may attenuate this risk. PMID:22591189

2012-01-01

363

Distinct iEEG activity patterns in temporal-limbic and prefrontal sites induced by emotional intentionality.  

PubMed

Our emotions tend to be directed towards someone or something. Such emotional intentionality calls for the integration between two streams of information; abstract hedonic value and its associated concrete content. In a previous functional magnetic resonance imaging (fMRI) study we found that the combination of these two streams, as modeled by short emotional music excerpts and neutral film clips, was associated with synergistic activation in both temporal-limbic (TL) and ventral-lateral PFC (vLPFC) regions. This additive effect implies the integration of domain-specific 'affective' and 'cognitive' processes. Yet, the low temporal resolution of the fMRI limits the characterization of such cross-domain integration. To this end, we complemented the fMRI data with intracranial electroencephalogram (iEEG) recordings from twelve patients with intractable epilepsy. As expected, the additive fMRI activation in the amygdala and vLPFC was associated with distinct spatio-temporal iEEG patterns among electrodes situated within the vicinity of the fMRI activation foci. On the one hand, TL channels exhibited a transient (0-500 msec) increase in gamma power (61-69 Hz), possibly reflecting initial relevance detection or hedonic value tagging. On the other hand, vLPFC channels showed sustained (1-12 sec) suppression of low frequency power (2.3-24 Hz), possibly mediating changes in gating, enabling an on-going readiness for content-based processing of emotionally tagged signals. Moreover, an additive effect in delta-gamma phase-amplitude coupling (PAC) was found among the TL channels, possibly reflecting the integration between distinct domain specific processes. Together, this study provides a multi-faceted neurophysiological signature for computations that possibly underlie emotional intentionality in humans. PMID:25288171

Singer, Neomi; Podlipsky, Ilana; Esposito, Fabrizio; Okon-Singer, Hadas; Andelman, Fani; Kipervasser, Svetlana; Neufeld, Miri Y; Goebel, Rainer; Fried, Itzhak; Hendler, Talma

2014-11-01

364

A smart sensor system for trace organic vapor detection using a temperature-controlled array of surface acoustic wave vapor sensors, automated preconcentrator tubes, and pattern recognition  

SciTech Connect

A smart sensor system for the detection, of toxic organophosphorus and toxic organosulfur vapors at trace concentrations has been designed, fabricated, and tested against a wide variety of vapor challenges. The key features of the system are: An array of four surface acoustic wave (SAW) vapor sensors, temperature control of the vapor sensors, the use of pattern recognition to analyze the sensor data, and an automated sampling system including thermally-desorbed preconcentrator tubes (PCTs).

Grate, J.W. [Pacific Northwest Lab., Richland, WA (United States); Rose-Pehrsson, S.L. [Naval Research Lab., Washington, DC (United States). Chemistry Div.; Klusty, M.; Wohltjen, H. [Microsensor Systems, Inc., Bowling Green, KY (United States)

1993-05-01

365

Temporal patterns of diversity: Assessing the biotic and abiotic controls on ant assemblages  

USGS Publications Warehouse

In this study, we use 12 months of data from 11 ant assemblages to test whether seasonal variation in ant diversity is governed by either the structuring influences of interspecific competition or environmental conditions. Because the importance of competition might vary along environmental gradients, we also test whether the signature of competition depends on elevation. We find little evidence that competition structures the seasonal patterns of activity in the ant assemblages considered, but find support for the effects of temperature on seasonal patterns of diversity, especially at low-elevation sites. Although, in general, both competition and the environment interact to structure ant assemblages, our results suggest that environmental conditions are the primary force structuring the seasonal activity of the ant assemblages studied here. ?? 2007 The Linnean Society of London.

Dunn, R.R.; Parker, C.R.; Sanders, N.J.

2007-01-01

366

An oscillatory circuit underlying the detection of disruptions in temporally-periodic patterns  

PubMed Central

Neurons in diverse brain areas can respond to the interruption of a regular stimulus pattern by firing bursts of spikes. Here we describe a simple model which permits such responses to periodic stimuli over a substantial frequency range. Focusing on the omitted stimulus response (OSR) in isolated retinas subjected to periodic patterns of dark flashes, we develop a pharmacologically-based model which accounts for resonances in ON bipolar cells. The bipolar cell terminal contains an LRC oscillator whose inductance is modulated by a transient calcium concentration, thus adjusting its resonant frequency to approximately match that of the stimulus. The model reproduces ganglion cell outputs, which sum the ON and OFF bipolar pathways, and it responds to omitted flashes with approximately constant latencies, as observed experimentally. PMID:19568983

Gao, Juan; Schwartz, Greg; Berry, Michael J.; Holmes, Philip

2009-01-01

367

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

PubMed Central

The goal of this survey was to analyze the spatio-temporal distribution patterns of Culicoides Latreille species (Diptera: Ceratopogonidae) and their relationship with environmental variables in Salta, northwestern Argentina. Culicoides were collected monthly from January 2003 through December 2005. The influence of the climatic variables on population abundance was analyzed with a multilevel Poisson regression. A total of 918 specimens belonging to five species were collected. The most abundant species was Culicoides paraensis Goeldi (65.5%), followed by Culicoides lahillei Iches (14.6%) and Culicoides debilipalpis Lutz (7.6%). The highest seasonal abundance for C. paraensis, C. debilipalpis and C. lahillei occurred during the spring and summer. A Poisson regression analysis showed that the mean maximum and minimum temperature and the mean maximum and minimum humidity were the variables with the greatest influence on the population abundance of Culicoides species. PMID:23461794

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

2012-01-01

368

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

PubMed Central

A classic problem in neuroscience is how temporal sequences (TSs) can be recognized. This problem is exemplified in the olfactory system, where an odor is defined by the TS of olfactory bulb (OB) output that occurs during a sniff. This sequence is discrete because the output is subdivided by gamma frequency oscillations. Here we propose a new class of “brute-force” solutions to recognition of discrete sequences. We demonstrate a network architecture in which there are a small number of modules, each of which provides a persistent snapshot of what occurs in a different gamma cycle. The collection of these snapshots forms a spatial pattern (SP) that can be recognized by standard attractor-based network mechanisms. We will discuss the implications of this strategy for recognizing odor-specific sequences generated by the OB. PMID:25278870

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

2014-01-01

369

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

PubMed Central

Microbes are key components of aquatic ecosystems and play crucial roles in global biogeochemical cycles. However, the spatiotemporal dynamics of planktonic microbial community composition in riverine ecosystems are still poorly understood. In this study, we used denaturing gradient gel electrophoresis of PCR-amplified 16S and 18S rRNA gene fragments and multivariate statistical methods to explore the spatiotemporal patterns and driving factors of planktonic bacterial and microbial eukaryotic communities in the subtropical Jiulong River, southeast China. Both bacterial and microbial eukaryotic communities varied significantly in time and were spatially structured according to upper stream, middle-lower stream and estuary. Among all the environmental factors measured, water temperature, conductivity, PO4-P and TN/TP were best related to the spatiotemporal distribution of bacterial community, while water temperature, conductivity, NOx-N and transparency were closest related to the variation of eukaryotic community. Variation partitioning, based on partial RDA, revealed that environmental factors played the most important roles in structuring the microbial assemblages by explaining 11.3% of bacterial variation and 17.5% of eukaryotic variation. However, pure spatial factors (6.5% for bacteria and 9.6% for eukaryotes) and temporal factors (3.3% for bacteria and 5.5% for eukaryotes) also explained some variation in microbial distribution, thus inherent spatial and temporal variation of microbial assemblages should be considered when assessing the impact of environmental factors on microbial communities. PMID:24244735

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

2013-01-01

370

Temporal distribution and spatial pattern of abundance of the Rift Valley fever and West Nile fever vectors in Barkedji, Senegal.  

PubMed

The temporal distribution and spatial pattern of abundance of mosquito vectors of Rift Valley fever (RVf) and West Nile fever (WNf) were studied during the 2005 and 2006 rainy seasons at Barkedji, Senegal. Mosquitoes were collected every two weeks with CDC light traps with dry ice at 79 sites including temporary ponds, barren, shrubby savannah, wooded savannah, steppes, and villages at different distances (between 0 and 600 m) from the nearest pond. The temporal distributions of these vectors varied between 2005 and 2006 and were positively correlated with rainfall for Aedes (Aedimorphus) vexans Patton, with rainfall after a lag time of one month for Culex (Culex) poicilipes (Theobald) and Culex (Culex) neavei Theobald. All the vectors had their highest abundances and parity rates between September and November. The highest vector abundances were observed in the barren and temporary ponds. The distance of trap location to the nearest ponds was negatively correlated to the abundance of the vectors. Taking into account the linear regression equations, it was predicted that mosquitoes would not disperse and be collected by the light trap, up to 1,500 m to the nearest ponds. The implications of these findings in the epidemiology and control of RVF and WNF at Barkedji are discussed. PMID:22129415

Diallo, Diawo; Talla, Cheikh; Ba, Yamar; Dia, Ibrahima; Sall, Amadou Alpha; Diallo, Mawlouth

2011-12-01

371

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

NASA Astrophysics Data System (ADS)

During spontaneous cell polarization of Dictyostelium discoideum cells, phosphatidylinositol (3,4,5)-triphoshpate (PIP3) and PTEN (phosphatase tensin homolog) have been identified as key signaling molecules which govern the process of polarization in a self-organized manner. Recent experiments have quantified the spatio-temporal dynamics of these signaling components. Surprisingly, it was found that membrane-bound PTEN can be either in a high or low state, that PIP3 waves were initiated in areas lacking PTEN through an excitable mechanism, and that PIP3 was degraded even though the PTEN concentration remained low. Here we develop a reaction-diffusion model that aims to explain these experimental findings. Our model contains bistable dynamics for PTEN, excitable dynamics for PIP3, and postulates the existence of two species of PTEN with different dephosphorylation rates. We show that our model is able to produce results that are in good qualitative agreement with the experiments, suggesting that our reaction-diffusion model underlies the self-organized spatio-temporal patterns observed in experiments.

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

2014-08-01

372

SuperFly: a comparative database for quantified spatio-temporal gene expression patterns in early dipteran embryos.  

PubMed

We present SuperFly (http://superfly.crg.eu), a relational database for quantified spatio-temporal expression data of segmentation genes during early development in different species of dipteran insects (flies, midges and mosquitoes). SuperFly has a special focus on emerging non-drosophilid model systems. The database currently includes data of high spatio-temporal resolution for three species: the vinegar fly Drosophila melanogaster, the scuttle fly Megaselia abdita and the moth midge Clogmia albipunctata. At this point, SuperFly covers up to 9 genes and 16 time points per species, with a total of 1823 individual embryos. It provides an intuitive web interface, enabling the user to query and access original embryo images, quantified expression profiles, extracted positions of expression boundaries and integrated datasets, plus metadata and intermediate processing steps. SuperFly is a valuable new resource for the quantitative comparative study of gene expression patterns across dipteran species. Moreover, it provides an interesting test set for systems biologists interested in fitting mathematical gene network models to data. Both of these aspects are essential ingredients for progress toward a more quantitative and mechanistic understanding of developmental evolution. PMID:25404137

Cicin-Sain, Damjan; Pulido, Antonio Hermoso; Crombach, Anton; Wotton, Karl R; Jiménez-Guri, Eva; Taly, Jean-François; Roma, Guglielmo; Jaeger, Johannes

2015-01-28

373

Temporal change in the landscape erosion pattern in the Yellow River Basin, China  

Microsoft Academic Search

Using Landsat TM data from 1995 and 2000, changes in the landscape erosion pattern of the Yellow River Basin, China were analysed. The aim was to improve our understanding of soil?erosion change so that sustainable land use could be established. First, a soil?erosion intensity index model was developed to study soil?erosion intensity change in the study area. Over the 5

W. Siyuan; L. Jingshi; Y. Cunjian

2007-01-01

374

Spatio-temporal patterns in Lateglacial and Holocene vegetation and climate of Finnmark, northernmost Europe  

NASA Astrophysics Data System (ADS)

Precisely-dated records of palaeovegetation and reconstructed palaeoclimate are presented from three lakes in northernmost Finnmark. The lakes lie adjacent to the southern shore of the Barents Sea and are located along a west-east transect. The three records are used to reconstruct spatial patterns in regional vegetation and climatic history since 13,900 cal yr BP. Longer-term shifts in treeline position and in the position of the Pinus-Betula ecotone are recorded. In addition, especially during the regional Holocene thermal maximum, the latter exhibited strong periodic fluctuations. The number and strength of these fluctuations that were recorded at each of the three sites differed systematically, with fewer and weaker fluctuations seen at the easternmost site, in particular. The patterns revealed are used to test the hypothesis that variations in the strength of the North Cape Current have been of primary importance as the proximal driver of climatic variability in the region since deglaciation. The results provide strong support for this hypothesis during the Holocene, the strong periodic fluctuations during the regional Holocene thermal maximum in particular being consistent with the proposed mechanism. During the Lateglacial and earliest Holocene the patterns are less clear, but nonetheless also consistent with the proposed mechanism. Further work on precisely-dated marine sediment cores will be necessary to understand the factors leading to the periodic and longer-term variations in strength of the North Cape Current.

Huntley, Brian; Long, Antony J.; Allen, Judy R. M.

2013-06-01

375

Spatial and Temporal Patterns of Deforestation in Rio Cajarí Extrative Reserve, Amapá, Brazil  

PubMed Central

The Rio Cajarí Extractive Reserve (RCER) is a sustainable use protected area located in Southern Amapá state, Brazil. This protected area is home to traditional agro-extractive families, but has been increasingly invaded by commercial agriculture producers. In this work, we test the hypothesis that the RCER implementation has distinctly affected spatial patterns of deforestation and rates of bare soil and secondary forest formation by the social groups occupying the protected area and its surrounding area. Detailed maps of vegetation cover and deforestation were elaborated, based on Landsat TM images from 1991, 1998, 2007 and 2008 and Linear Spectral Mixture Models. Based on an extensive fieldwork, patches were classified according to the agents causing deforestation and characterized with ten explanatory variables. A discriminant function analysis was used to identify homogeneous groups based on the data. Results show increased rates and distinct spatial patterns of deforestation by three groups: extractivists, non traditional commercial agriculture producers, and a less representative group constituted of miners, cattle and timber producers. In all analyzed dates, clearings by the extrativist community presented the highest total area and smaller average sizes and were located in close proximity to villages. Deforestation patches by the non-traditional group were exclusively associated with ombrophilous forests; these presented higher average sizes and proximity indexes, and showed increased aggregation and large cluster formation. No significant differences were observed in deforestation patterns by the three groups inside or outside the reserve. PMID:23284806

Funi, Claudia; Paese, Adriana

2012-01-01

376

A spatial mixture approach to inferring sub-ROI spatio-temporal patterns from rapid event-related fMRI data.  

PubMed

Previous works investigated a range of spatio-temporal models for fMRI data analysis to provide robust determination of functional region-of-interest (ROI). We present a novel spatio-temporal fMRI model that is suitable for identifying a number of distinct temporal patterns and their spatial support in the voxel space. Accordingly, fMRI signals on a single voxel are modeled as a probabilistic superposition of those temporal patterns. The spatially varying influence of individual patterns is defined in terms of a parameterised function. The temporal pattern is characterised by both the underlying hemodynamic response function (HRF) and a time series of the individual stimulus-response magnitudes, which makes the proposed model particularly suitable for modeling rapid event-related fMRI data. Moreover, a parametric approach is adopted to represent the HRFs. The resulting methodology is conceptually principled and computationally efficient. We first verify the proposed model in a controlled experimental setting using synthetic data. The model is further applied to analyzing real fMRI data, with focus on functional homogeneity within individual ROIs. PMID:24579197

Shen, Yuan; Mayhew, Stephen; Kourtzi, Zoe; Tino, Peter

2013-01-01

377

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

PubMed Central

At least ten species of beaked whales inhabit the North Pacific, but little is known about their abundance, ecology, and behavior, as they are elusive and difficult to distinguish visually at sea. Six of these species produce known species-specific frequency modulated (FM) echolocation pulses: Baird’s, Blainville’s, Cuvier’s, Deraniyagala’s, Longman’s, and Stejneger’s beaked whales. Additionally, one described FM pulse (BWC) from Cross Seamount, Hawai’i, and three unknown FM pulse types (BW40, BW43, BW70) have been identified from almost 11 cumulative years of autonomous recordings at 24 sites throughout the North Pacific. Most sites had a dominant FM pulse type with other types being either absent or limited. There was not a strong seasonal influence on the occurrence of these signals at any site, but longer time series may reveal smaller, consistent fluctuations. Only the species producing BWC signals, detected throughout the Pacific Islands region, consistently showed a diel cycle with nocturnal foraging. By comparing stranding and sighting information with acoustic findings, we hypothesize that BWC signals are produced by ginkgo-toothed beaked whales. BW43 signal encounters were restricted to Southern California and may be produced by Perrin’s beaked whale, known only from Californian waters. BW70 signals were detected in the southern Gulf of California, which is prime habitat for Pygmy beaked whales. Hubb’s beaked whale may have produced the BW40 signals encountered off central and southern California; however, these signals were also recorded off Pearl and Hermes Reef and Wake Atoll, which are well south of their known range. PMID:24465877

Baumann-Pickering, Simone; Roch, Marie A.; Brownell Jr, Robert L.; Simonis, Anne E.; McDonald, Mark A.; Solsona-Berga, Alba; Oleson, Erin M.; Wiggins, Sean M.; Hildebrand, John A.

2014-01-01

378

Using Optimality Principles to Predict Spatio-Temporal Patterns of Vegetation-Atmosphere Fluxes at Leaf to Global Scales  

NASA Astrophysics Data System (ADS)

A predictive understanding of biological variation in space and time -- from spatial gradients of light within plant canopies, seasonal fluctuations in temperature and water availability during a growing season, to geographic variation in climate and soil nutrient availability across the land surface -- is a central but challenging goal in biospheric sciences. Functional attributes of vegetation, such as the capacities to exchange carbon, water and energy with the atmosphere, can be assessed based on thermodynamic and aerodynamic properties of the canopy-atmosphere system, however many of these properties cannot be directly measured at the global scale. In lieu of direct measurement, optimization methods based on simplifying theories of the underlying processes, including Maximum Entropy Production (MEP) and economic theories of plant carbon and water relations, are needed to provide sufficient constraint to estimate the required parameters. Using theories of functional coordination in which it is assumed that plants maintain a balance between the supply and demand of a variable (e.g. absorbed radiation, CO2, water) consistent with MEP in complex source-sink physiological systems, it is possible to predict spatial patterns of leaf photosynthetic capacity within plant canopies as well as their temporal variation throughout the growing season. When combined with satellite remote sensing observations of canopy light absorptance (fAPAR), these same theories can be used to predict seasonal variations in leaf and canopy photosynthesis and transpiration, and global spatio-temporal patterns of productivity and evapotranspiration. Predictions using this approach are consistent with observations at leaf to landscape scales based on leaf gas exchange and eddy covariance measurements in arctic to tropical ecosystems.

Tu, K. P.

2008-12-01

379

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

PubMed

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

Zhan, Yu; Zhang, Minghua

2014-02-15

380

Are There Spatial or Temporal Patterns to Holocene Explosive Eruptions in the Aleutian Archipelago? A Work in Progress  

NASA Astrophysics Data System (ADS)

By examining the existing geological and archeological record of radiocarbon dated Aleutian tephras of the last 12,000 years, this study sought to determine whether there were spatial or temporal patterns of explosive eruptive activity. The Holocene tephra record has important implications because two episodes of migration and colonization by humans of distinct cultures established the Unangan/Aleut peoples of the Aleutian Islands concurrently with the volcanic activity. From Aniakchak Volcano on the Alaska Peninsula to the Andreanof Islands (158 to 178° W longitude), 55 distinct tephras represent significant explosive eruptions of the last 12,000 years. Initial results suggest that the Andreanof and Fox Island regions of the archipelago have had frequent explosive eruptions whereas the Islands of Four Mountains, Rat, and Near Island regions have apparently had little or no eruptive activity. However, one clear result of the investigation is that sampling bias strongly influences the apparent spatial patterns. For example field reconnaissance in the Islands of Four Mountains documents two Holocene calderas and a minimum of 20 undated tephras in addition to the large ignimbrites. Only the lack of significant explosive activity in the Near Islands seems a valid spatial result as archeological excavations and geologic reports failed to document Holocene tephras there. An intriguing preliminary temporal pattern is the apparent absence of large explosive eruptions across the archipelago from ca. 4,800 to 6,000 yBP. To test the validity of apparent patterns, a statistical treatment of the compiled data grappled with the sampling bias by considering three confounding variables: larger island size allows more opportunity for geologic preservation of tephras; larger magnitude eruption promotes tephra preservation by creating thicker and more widespread deposits; the comprehensiveness of the tephra sampling of each volcano and island varies widely because of logistical and financial limitations. This initial statistical investigation proposes variables to mitigate the effects of sampling bias and makes recommendations for sampling strategies to enable statistically valid examination of research questions. Further, though caldera-forming eruptions occurred throughout the Holocene - and several remain undated - four of six dated eruptions occurred throughout the archipelago between 8,000-9,100 yBP, a period coinciding with some of the earliest human occupation (Early Anangula Phase) of the eastern Aleutians.

Martin, C.; Nicolaysen, K. P.; McConville, K.; Hatfield, V.; West, D.

2013-12-01

381

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

382

Temporal firing patterns of Purkinje cells in the cerebellar ventral paraflocculus during ocular following responses in monkeys II. Complex spikes.  

PubMed

Many theories of cerebellar motor learning propose that complex spikes (CS) provide essential error signals for learning and modulate parallel fiber inputs that generate simple spikes (SS). These theories, however, do not satisfactorily specify what modality is represented by CS or how information is conveyed by the ultra-low CS firing rate (1 Hz). To further examine the function of CS and the relationship between CS and SS in the cerebellum, CS and SS were recorded in the ventral paraflocculus (VPFL) of awake monkeys during ocular following responses (OFR). In addition, a new statistical method using a generalized linear model of firing probability based on a binomial distribution of the spike count was developed for analysis of the ultra-low CS firing rate. The results of the present study showed that the spatial coordinates of CS were aligned with those of SS and the speed-tuning properties of CS and SS were more linear for eye movement than retinal slip velocity, indicating that CS contain a motor component in addition to the sensory component identified in previous studies. The generalized linear model to reproduce firing probability confirmed these results, demonstrating that CS conveyed high-frequency information with its ultra-low firing frequency and conveyed both sensory and motor information. Although the temporal patterns of the CS were similar to those of the SS when the sign was reversed and magnitude was amplified approximately 50 times, the velocity/acceleration coefficient ratio of the eye movement model, an aspect of the CS temporal firing profile, was less than that of the SS, suggesting that CS were more sensory in nature than SS. A cross-correlation analysis of SS that are triggered by CS revealed that short-term modulation, that is, the brief pause in SS caused by CS, does not account for the reciprocal modulation of SS and CS. The results also showed that three major aspects of the CS and SS individual cell firing characteristics were negatively correlated on a cell-to-cell basis: the preferred direction of stimulus motion, the mean percent change in firing rate induced by upward stimulus motion, and patterns of temporal firing probability. These results suggest that CS may contribute to long-term interactions between parallel and climbing fiber inputs, such as long-term depression and/or potentiation. PMID:9705472

Kobayashi, Y; Kawano, K; Takemura, A; Inoue, Y; Kitama, T; Gomi, H; Kawato, M

1998-08-01

383

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 ...

384

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

PubMed

No multi-site comparisons have tested whether seasonally cold temperature or climate exacerbate pain intensity in sickle cell disease (SCD). We examined seasonal SCD pain intensity and frequency patterns and compared them with concurrent climate conditions (temperature and barometric pressure) and geography of patient residence in the Multicenter Study of Hydroxyurea (MSH). We conducted a time series analysis of the monthly average daily pain intensity (0-9 scale) and pain frequency of the 299 MSH patients from December 1991 to December 1994. We used both an unobserved component model (UCM) and a nonparametric local regression (LOESS) to probe for a cycle and/or trend associated with the time series. We also examined base mixed regression models of season, monthly average temperature and barometric pressure, and geographic region as stand-alone predictors of pain intensity and frequency. Expanded models included additional predictor variables. UCM and LOESS analyses showed a cyclic pattern of pain intensity and frequency with peaks in late Fall/early Winter and troughs in Spring. Base regression models showed colder seasons were significantly associated with greater pain intensity (p = .0035) but not frequency (p = .07); higher monthly temperatures were significantly associated with both lower pain intensity and pain frequency, but higher monthly barometric pressures were significantly associated with greater pain intensity and frequency (all p's < .0001); and northern sites had nonsignificantly higher pain intensity (p = .40) and frequency (p = .07) than southern sites. This pattern of results did not change in expanded models including other predictors. Our results suggest that seasonably colder temperatures exacerbate sickle cell-related pain, but low barometric pressure does not, and geographic region of residence is not significantly related to pain in this sample. PMID:19683393

Smith, Wally R; Bauserman, Robert L; Ballas, Samir K; McCarthy, William F; Steinberg, Martin H; Swerdlow, Paul S; Waclawiw, Myron A; Barton, Bruce A

2009-11-01

385

Temporal Patterns of Happiness and Information in a Global Social Network: Hedonometrics and Twitter  

PubMed Central

Individual happiness is a fundamental societal metric. Normally measured through self-report, happiness has often been indirectly characterized and overshadowed by more readily quantifiable economic indicators such as gross domestic product. Here, we examine expressions made on the online, global microblog and social networking service Twitter, uncovering and explaining temporal variations in happiness and information levels over timescales ranging from hours to years. Our data set comprises over 46 billion words contained in nearly 4.6 billion expressions posted over a 33 month span by over 63 million unique users. In measuring happiness, we construct a tunable, real-time, remote-sensing, and non-invasive, text-based hedonometer. In building our metric, made available with this paper, we conducted a survey to obtain happiness evaluations of over 10,000 individual words, representing a tenfold size improvement over similar existing word sets. Rather than being ad hoc, our word list is chosen solely by frequency of usage, and we show how a highly robust and tunable metric can be constructed and defended. PMID:22163266

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

2011-01-01

386

Spatial and Temporal Patterns of Apparent Electrical Conductivity: DUALEM vs. Veris Sensors for Monitoring Soil Properties  

PubMed Central

The main objective of this study was to compare two apparent soil electrical conductivity (ECa) sensors (Veris 2000 XA and DUALEM 1S) for mapping variability of soil properties in a Mediterranean shallow soil. This study also aims at studying the effect of soil cover vegetation on the ECa measurement by the two types of sensors. The study was based on two surveys carried out under two very different situations: in February of 2012, with low soil moisture content (SMC) and with high and differentiated vegetation development (non grazed pasture), and in February of 2013, with high SMC and with short and relatively homogeneous vegetation development (grazed pasture). The greater temporal stability of Veris sensor, despite the wide variation in the SMC and vegetation ground cover indicates the suitability of using this sensor for monitoring soil properties in permanent pastures. The survey carried out with the DUALEM sensor in 2012 might have been affected by the presence of a 0.20 m vegetation layer at the soil surface, masking the soil properties. These differences should be considered in the selection of ECa sensing systems for a particular application. PMID:24915182

Serrano, João; Shahidian, Shakib; da Silva, José Marques

2014-01-01

387

Assessing the temporal stability of spatial patterns of soil apparent electrical conductivity using geophysical methods  

NASA Astrophysics Data System (ADS)

Cocoa remains in the same field for decades, resulting in plantations dominated with aging trees growing on variable and depleted soils. We determined the spatio-temporal variability of key soil properties in a (5.81 ha) field from the International Cocoa Genebank, Trinidad using geophysical methods. Multi-year (2008-2009) measurements of apparent electrical conductivity at 0-0.75 m (shallow) and 0.75-1.5 m (deep) were conducted. Apparent electrical conductivity at deep and shallow gave the strongest linear correlation with clay-silt content (R = 0.67 and R = 0.78, respectively) and soil solution electrical conductivity (R = 0.76 and R = 0.60, respectively). Spearman rank correlation coefficients ranged between 0.89-0.97 and 0.81- 0.95 for apparent electrical conductivity at deep and shallow, respectively, signifying a strong linear dependence between measurement days. Thus, in the humid tropics, cocoa fields with thick organic litter layer and relatively dense understory cover, experience minimal fluctuations in transient properties of soil water and temperature at the topsoil resulting in similarly stable apparent electrical conductivity at shallow and deep. Therefore, apparent electrical conductivity at shallow, which covers the depth where cocoa feeder roots concentrate, can be used as a fertility indicator and to develop soil zones for efficient application of inputs and management of cocoa fields.

De Caires, Sunshine A.; Wuddivira, Mark N.; Bekele, Isaac

2014-10-01

388

A typology of household-level adaptation to coastal flooding and its spatio-temporal patterns.  

PubMed

The predicted sea-level rise and changes in storm surge regimes are expected to lead to an increasing risk of flooding in coastal regions. Accommodation can be an alternative to protection in many areas, with household-level adaptation potentially constituting an important element of such a strategy, as it can significantly reduce costs. To date, a systematic typology of household-level adaptation to coastal flooding does not exist. In order to bridge this gap, we conducted a series of quantitative surveys in different coastal areas in Denmark, Germany and Argentina. We applied a cluster analysis in order to categorise the adaptive behaviour of coastal households. Coastal households were found to cluster in four groups that we term: the comprehensives, the theoreticians, the minimalists and the structurals. With the exception of households focusing on the implementation of high-effort structural measures, our results show the affiliation to these groups to follow a specific temporal sequence. At the same time, large differences in category affiliation exist between the study areas. Risk communication tools can utilise our typology to selectively target specific types of households or to ensure that the information needs of all groups are addressed. PMID:25191638

Koerth, Jana; Vafeidis, Athanasios T; Carretero, Silvina; Sterr, Horst; Hinkel, Jochen

2014-01-01

389

Robust movement direction decoders from local field potentials using spatio-temporal qualitative patterns.  

PubMed

A major drawback of using Local Field Potentials (LFP) for Brain Computer Interface (BCI) is their inherent instability and non-stationarity. Specifically, even when a well-trained subject performs the same task over a period of time, the neural data observed are unstable. To overcome this problem in decoding movement direction, this paper proposes the use of qualitative information in the form of spatial patterns of inter-channel ranking of multi-channel LFP recordings. The quality of the decoding was further refined by concentrating on the statistical distributions of the top powered channels. Decoding of movement direction was performed using Support Vector Machines (SVM) to construct decoders, instead of the traditional spatial patterns. Our algorithm provides a decoding power of up to 74% on average over a period of two weeks, compared with the state-of-the-art methods in the literature that yield only 33%. Furthermore, it provides 62.5% direction decoding in novel motor environments, compared with 29.5% with conventional methods. Finally, a comparison with the traditional methods and other surveyed literature is presented. PMID:23366958

Tadipatri, Vijay Aditya; Tewfik, Ahmed H; Ashe, James; Pellizzer, Giuseppe

2012-01-01

390

Spatial and Temporal Fracture Pattern in Breast and Gynecologic Cancer Survivors  

PubMed Central

Objective(s): To assess skeletal wide fracture location and time of fracture after cancer treatment Study Design: One hundred thirty-nine women diagnosed with breast or gynecologic cancer between 2003 and 2012 that subsequently had a radiologic diagnosis of fracture were identified retrospectively using electronic medical records. Results were compared with skeletal fracture pattern previously reported for a general population. Results: Skeletal fractures in cancer patients occur throughout the entire skeleton similar to general population. The most common sites were vertebrae (16%), feet and toes (15%), ribs (12%), hands and fingers (10%), and pelvis (8%). Fracture incidence was observed starting within the first year of survivorship, and continued to after five years. The median time from cancer diagnosis to fracture varied by age (p<0.01), from a high of 3.2 years for ages 50-59 to a low of 1.2 years for patients older than 70. Conclusion: The pattern of skeletal fracture is similar between cancer survivor and general population. Contrary to general assumption, survivors can experience skeletal fracture early after cancer treatment, especially at an older age. Thus, cancer survivorship care should include assessment of early time points with improved management of cancer treatment related bone injury. PMID:25553090

Hui, Susanta K; Arentsen, Luke; Wilcox, Anjali; Shanley, Ryan; Yee, Douglas; Ghebre, Rahel

2015-01-01

391

Spatio-temporal patterns of ptarmigan occupancy relative to shrub cover in the Arctic  

USGS Publications Warehouse

Rock and willow ptarmigan are abundant herbivores that require shrub habitats in arctic and alpine areas. Shrub expansion is likely to increase winter habitat availability for ptarmigan, which in turn influence shrub architecture and growth through browsing. Despite their ecological role in the Arctic, the distribution and movement patterns of ptarmigan are not well known, particularly in northern Alaska where shrub expansion is occurring. We used multi-season occupancy models to test whether ptarmigan occupancy varied within and among years, and the degree to which colonization and extinction probabilities were related to shrub cover and latitude. Aerial surveys were conducted from March to May in 2011 and April to May 2012 in a 21,230 km2 area in northeastern Alaska. In areas with at least 30 % shrub cover, the probability of colonization by ptarmigan was >0.90, indicating that moderate to extensive patches of shrubs (typically associated with riparian areas) had a high probability of becoming occupied by ptarmigan. Occupancy increased throughout the spring in both years, providing evidence that ptarmigan migrated from southern wintering areas to breeding areas north of the Brooks Range. Occupancy was higher in the moderate snow year than the high snow year, and this was likely due to higher shrub cover in the moderate snow year. Ptarmigan distribution and migration in the Arctic are linked to expanding shrub communities on a wide geographic scale, and these relationships may be shaping ptarmigan population dynamics, as well as rates and patterns of shrub expansion.

Schmutz, Joel A.

2014-01-01

392

Spatio-temporal and species-specific variation in PBDE levels/patterns in British Columbia's coastal waters.  

PubMed

Congener-specific levels of PBDEs were measured in the livers and some muscle tissues of Dungeness crab (Cancer magister), English sole (Pleuronectes vetulus) and spiny dogfish (Squalus acanthias). Highest concentrations (1,200-560 ng/g lipid) were found in crab collected near heavily urbanized areas (pop. approximately 0.3-1.8 million), followed by moderate levels at pulp/paper mills sites ( approximately 150 ng/g), and lowest levels occurred in areas that were somewhat removed from industrial/populated areas (< 24 ng/g). Temporal increases in total PBDEs and particularly in BDE-47 for Dungeness crab collected near pulp and paper and urbanized areas between 1994 and 2000 were observed. These correspond to Canadian and worldwide trends seen for PBDEs in biota. English sole and dogfish showed a pattern similar to that of the Columbia River whitefish samples, which corresponded closely to the patterns in the "penta" commercial mixture. Conversely, Dungeness crab were enriched in lower chlorinated PBDEs, particularly BDE-47 and BDE-49, compared to the fish and shark species from BC. PMID:16219403

Ikonomou, Michael G; Fernandez, Marc P; Hickman, Zachary L

2006-03-01

393

Temporal metatranscriptomic patterning in phototrophic Chloroflexi inhabiting a microbial mat in a geothermal spring  

PubMed Central

Filamentous anoxygenic phototrophs (FAPs) are abundant members of microbial mat communities inhabiting neutral and alkaline geothermal springs. Natural populations of FAPs related to Chloroflexus spp. and Roseiflexus spp. have been well characterized in Mushroom Spring, where they occur with unicellular cyanobacteria related to Synechococcus spp. strains A and B?. Metatranscriptomic sequencing was applied to the microbial community to determine how FAPs regulate their gene expression in response to fluctuating environmental conditions and resource availability over a diel period. Transcripts for genes involved in the biosynthesis of bacteriochlorophylls (BChls) and photosynthetic reaction centers were much more abundant at night. Both Roseiflexus spp. and Chloroflexus spp. expressed key genes involved in the 3-hydroxypropionate (3-OHP) carbon dioxide fixation bi-cycle during the day, when these FAPs have been thought to perform primarily photoheterotrophic and/or aerobic chemoorganotrophic metabolism. The expression of genes for the synthesis and degradation of storage polymers, including glycogen, polyhydroxyalkanoates and wax esters, suggests that FAPs produce and utilize these compounds at different times during the diel cycle. We summarize these results in a proposed conceptual model for temporal changes in central carbon metabolism and energy production of FAPs living in a natural environment. The model proposes that, at night, Chloroflexus spp. and Roseiflexus spp. synthesize BChl, components of the photosynthetic apparatus, polyhydroxyalkanoates and wax esters in concert with fermentation of glycogen. It further proposes that, in daytime, polyhydroxyalkanoates and wax esters are degraded and used as carbon and electron reserves to support photomixotrophy via the 3-OHP bi-cycle. PMID:23575369

Klatt, Christian G; Liu, Zhenfeng; Ludwig, Marcus; Kühl, Michael; Jensen, Sheila I; Bryant, Donald A; Ward, David M

2013-01-01

394

Temporal metatranscriptomic patterning in phototrophic Chloroflexi inhabiting a microbial mat in a geothermal spring.  

PubMed

Filamentous anoxygenic phototrophs (FAPs) are abundant members of microbial mat communities inhabiting neutral and alkaline geothermal springs. Natural populations of FAPs related to Chloroflexus spp. and Roseiflexus spp. have been well characterized in Mushroom Spring, where they occur with unicellular cyanobacteria related to Synechococcus spp. strains A and B'. Metatranscriptomic sequencing was applied to the microbial community to determine how FAPs regulate their gene expression in response to fluctuating environmental conditions and resource availability over a diel period. Transcripts for genes involved in the biosynthesis of bacteriochlorophylls (BChls) and photosynthetic reaction centers were much more abundant at night. Both Roseiflexus spp. and Chloroflexus spp. expressed key genes involved in the 3-hydroxypropionate (3-OHP) carbon dioxide fixation bi-cycle during the day, when these FAPs have been thought to perform primarily photoheterotrophic and/or aerobic chemoorganotrophic metabolism. The expression of genes for the synthesis and degradation of storage polymers, including glycogen, polyhydroxyalkanoates and wax esters, suggests that FAPs produce and utilize these compounds at different times during the diel cycle. We summarize these results in a proposed conceptual model for temporal changes in central carbon metabolism and energy production of FAPs living in a natural environment. The model proposes that, at night, Chloroflexus spp. and Roseiflexus spp. synthesize BChl, components of the photosynthetic apparatus, polyhydroxyalkanoates and wax esters in concert with fermentation of glycogen. It further proposes that, in daytime, polyhydroxyalkanoates and wax esters are degraded and used as carbon and electron reserves to support photomixotrophy via the 3-OHP bi-cycle. PMID:23575369

Klatt, Christian G; Liu, Zhenfeng; Ludwig, Marcus; Kühl, Michael; Jensen, Sheila I; Bryant, Donald A; Ward, David M

2013-09-01

395

Multispecies spawning sites for fishes on a low-latitude coral reef: spatial and temporal patterns.  

PubMed

Spawning sites used by one or more species were located by intensively searching nearshore coral reefs of Kimbe Bay (New Britain, Papua New Guinea). Once identified, the spawning sites were surveyed repeatedly within fixed 5?m radius circular areas, for ?>?2000 h of observations ranging from before dawn to after dusk spanning 190 days between July 2001 and May 2004. A total of 38 spawning sites were identified on the seven study reefs distributed at an average of one site every 60?m of reef edge. Pelagic spawning was observed in 41 fish species from six families. On three intensively studied reefs, all 17 spawning sites identified were used by at least three species, with a maximum of 30 different species observed spawning at a single site. Spawning was observed during every month of the study, on all days of the lunar month, at all states of the tide and at most hours of the day studied. Nevertheless, the majority of species were observed spawning on proportionately more days from December to April, on more days around the new moon and in association with higher tides. The strongest temporal association, however, was with species-specific diel spawning times spanning?

Claydon, J A B; McCormick, M I; Jones, G P

2014-04-01

396

Use of temporal patterns in vapor pressure deficit to explain spatial autocorrelation dynamics in tree transpiration.  

PubMed

To quantify the relationship between temporal and spatial variation in tree transpiration, we measured sap flow in 129 trees with constant-heat sap flow sensors in a subalpine forest in southern Wyoming, USA. The forest stand was located along a soil water gradient from a stream side to near the top of a ridge. The stand was dominated by Pinus contorta Dougl. ex Loud. with Picea engelmannii Parry ex Engelm and Abies lasiocarpa (Hook.) Nutt. present near the stream and scattered individuals of Populus tremuloides Michx. throughout the stand. We used a cyclic sampling design that maximized spatial information with a minimum number of samples for semivariogram analyses. All species exhibited previously established responses to environmental variables in which the dominant driver was a saturating response to vapor pressure deficit (D). This response to D is predictable from tree hydraulic theory in which stomatal conductance declines as D increases to prevent excessive cavitation. The degree to which stomatal conductance declines with D is dependent on both species and individual tree physiology and increases the variability in transpiration as D increases. We quantified this variability spatially by calculating the spatial autocorrelation within 0.2-kPa D bins. Across 11 bins of D, spatial autocorrelation in individual tree transpiration was inversely correlated to D and dropped from 45 to 20 m. Spatial autocorrelation was much less for transpiration per unit leaf area and not significant for transpiration per unit sapwood area suggesting that spatial autocorrelation within a particular D bin could be explained by tree size. Future research should focus on the mechanisms underlying tree size spatial variability, and the potentially broad applicability of the inverse relationship between D and spatial autocorrelation in tree transpiration. PMID:18244950

Adelman, Jonathan D; Ewers, Brent E; Mackay, D Scott

2008-04-01

397

Arabidopsis Roots and Shoots Show Distinct Temporal Adaptation Patterns toward Nitrogen Starvation1[W  

PubMed Central

Nitrogen (N) is an essential macronutrient for plants. N levels in soil vary widely, and plants have developed strategies to cope with N deficiency. However, the regulation of these adaptive responses and the coordinating signals that underlie them are still poorly understood. The aim of this study was to characterize N starvation in adult Arabidopsis (Arabidopsis thaliana) plants in a spatiotemporal manner by an integrative, multilevel global approach analyzing growth, metabolites, enzyme activities, and transcript levels. We determined that the remobilization of N and carbon compounds to the growing roots occurred long before the internal N stores became depleted. A global metabolite analysis by gas chromatography-mass spectrometry revealed organ-specific differences in the metabolic adaptation to complete N starvation, for example, for several tricarboxylic acid cycle intermediates, but also for carbohydrates, secondary products, and phosphate. The activities of central N metabolism enzymes and the capacity for nitrate uptake adapted to N starvation by favoring N remobilization and by increasing the high-affinity nitrate uptake capacity after long-term starvation. Changes in the transcriptome confirmed earlier studies and added a new dimension by revealing specific spatiotemporal patterns and several unknown N starvation-regulated genes, including new predicted small RNA genes. No global correlation between metabolites, enzyme activities, and transcripts was evident. However, this multilevel spatiotemporal global study revealed numerous new patterns of adaptation mechanisms to N starvation. In the context of a sustainable agriculture, this work will give new insight for the production of crops with increased N use efficiency. PMID:21900481

Krapp, Anne; Berthomé, Richard; Orsel, Mathilde; Mercey-Boutet, Stéphanie; Yu, Agnes; Castaings, Loren; Elftieh, Samira; Major, Hilary; Renou, Jean-Pierre; Daniel-Vedele, Françoise

2011-01-01

398

Spatio-Temporal Brain Mapping of Spatial Attention Effects on Pattern-Reversal ERPs  

PubMed Central

Recordings of event-related potentials (ERPs) were combined with structural and functional magnetic resonance imaging (fMRI) to investigate the timing and localization of stimulus selection processes during visual-spatial attention to pattern-reversing gratings. Pattern reversals were presented in random order to the left and right visual fields at a rapid rate while subjects attended to the reversals in one field at a time. On separate runs stimuli were presented in the upper and lower visual quadrants. The earliest ERP component (C1, peaking at around 80 ms), which inverted in polarity for upper versus lower field stimuli and was localized in or near visual area V1, was not modulated by attention. In the latency range 80-250 ms multiple components were elicited that were increased in amplitude by attention and were co-localized with fMRI activations in specific visual cortical areas. The principal anatomical sources of these attention-sensitive components were localized by fMRI-seeded dipole modeling as follows: P1 (ca. 100 ms--source in motion-sensitive area MT+), C2 (ca. 130 ms-- same source as C1), N1a (ca. 145 ms-- source in horizontal intraparietal sulcus), N1b (ca. 165 ms-- source in fusiform gyrus, area V4/V8), N1c (ca. 180 ms-- source in posterior intraparietal sulcus, area V3A), and P2 (ca. 220