Science.gov

Sample records for operators temporally stable

  1. Stable operating regime for traveling wave devices

    DOEpatents

    Carlsten, Bruce E.

    2000-01-01

    Autophase stability is provided for a traveling wave device (TWD) electron beam for amplifying an RF electromagnetic wave in walls defining a waveguide for said electromagnetic wave. An off-axis electron beam is generated at a selected energy and has an energy noise inherently arising from electron gun. The off-axis electron beam is introduced into the waveguide. The off-axis electron beam is introduced into the waveguide at a second radius. The waveguide structure is designed to obtain a selected detuning of the electron beam. The off-axis electron beam has a velocity and the second radius to place the electron beam at a selected distance from the walls defining the waveguide, wherein changes in a density of the electron beam due to the RF electromagnetic wave are independent of the energy of the electron beam to provide a concomitant stable operating regime relative to the energy noise.

  2. Temporally-stable active precision mount for large optics.

    PubMed

    Reinlein, Claudia; Damm, Christoph; Lange, Nicolas; Kamm, Andreas; Mohaupt, Matthias; Brady, Aoife; Goy, Matthias; Leonhard, Nina; Eberhardt, Ramona; Zeitner, Uwe; Tünnermann, Andreas

    2016-06-13

    We present a temporally-stable active mount to compensate for manufacturing-induced deformations of reflective optical components. In this paper, we introduce the design of the active mount, and its evaluation results for two sample mirrors: a quarter mirror of 115 × 105 × 9 mm3, and a full mirror of 228 × 210 × 9 mm3. The quarter mirror with 20 actuators shows a best wavefront error rms of 10 nm. Its installation position depending deformations are addressed by long-time measurements over 14 weeks indicating no significance of the orientation. Size-induced differences of the mount are studied by a full mirror with 80 manual actuators arranged in the same actuator pattern as the quarter mirror. This sample shows a wavefront error rms of (27±2) nm over a measurement period of 46 days. We conclude that the developed mount is suitable to compensate for manufacturing-induced deformations of large reflective optics, and likely to be included in the overall systems alignment procedure. PMID:27410369

  3. Regularity theory for general stable operators

    NASA Astrophysics Data System (ADS)

    Ros-Oton, Xavier; Serra, Joaquim

    2016-06-01

    We establish sharp regularity estimates for solutions to Lu = f in Ω ⊂Rn, L being the generator of any stable and symmetric Lévy process. Such nonlocal operators L depend on a finite measure on S n - 1, called the spectral measure. First, we study the interior regularity of solutions to Lu = f in B1. We prove that if f is Cα then u belong to C α + 2 s whenever α + 2 s is not an integer. In case f ∈L∞, we show that the solution u is C2s when s ≠ 1 / 2, and C 2 s - ɛ for all ɛ > 0 when s = 1 / 2. Then, we study the boundary regularity of solutions to Lu = f in Ω, u = 0 in Rn ∖ Ω, in C 1 , 1 domains Ω. We show that solutions u satisfy u /ds ∈C s - ɛ (Ω ‾) for all ɛ > 0, where d is the distance to ∂Ω. Finally, we show that our results are sharp by constructing two counterexamples.

  4. Renormalizing Operator-Stable Lagrangian Velocities for Microbial Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Cushman, J. H.; Park, M.

    2008-05-01

    In previous works we've developed upscaling methodologies for stable Levy Lagrangian velocities in fractal media. The renormalization tools were generalized central limit theorems which are equivalent to a renormalization group approach. Here we extend these ides to operator-stable Lagrangian velocities and apply the results to microbial dynamics in multi-scale geologic formations. Renormalized Fokker-Planck equations are presented at each scale.

  5. Fiber Optic Cable Thermal Preparation to Ensure Stable Operation

    NASA Technical Reports Server (NTRS)

    Thoames Jr, William J.; Chuska, Rick F.; LaRocca, Frank V.; Switzer, Robert C.; Macmurphy, Shawn L.; Ott, Melanie N.

    2008-01-01

    Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50 C up to 125 C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission.

  6. Operations automation using temporal dependency networks

    NASA Technical Reports Server (NTRS)

    Cooper, Lynne P.

    1991-01-01

    Precalibration activities for the Deep Space Network are time- and work force-intensive. Significant gains in availability and efficiency could be realized by intelligently incorporating automation techniques. An approach is presented to automation based on the use of Temporal Dependency Networks (TDNs). A TDN represents an activity by breaking it down into its component pieces and formalizing the precedence and other constraints associated with lower level activities. The representations are described which are used to implement a TDN and the underlying system architecture needed to support its use. The commercial applications of this technique are numerous. It has potential for application in any system which requires real-time, system-level control, and accurate monitoring of health, status, and configuration in an asynchronous environment.

  7. Spatial and Temporal Trends in Stable Carbon and Oxygen Isotope Ratios of Juvenile Winter Flounder

    EPA Science Inventory

    Isotopic ratios of fish otoliths have been used in numerous studies as natural tags or markers to aid the study of connectivity among fish populations. We investigated the use of spatial and temporal changes in the stable carbon and oxygen isotope ratios of otoliths to different...

  8. Spatial-temporal dynamics of stable fly (Diptera:muscidae) trap catches in eastern Nebraska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial and temporal relationships among catches of adult stable flies on sticky traps in eastern Nebraska were evaluated. Twenty-five alsynite sticky traps were placed in a 5 × 5 grid with ˜1.6 km intervals in a mixed agricultural environment from 2003 to 2011. Denser grids of 45-90 traps were impl...

  9. Switchable genetic oscillator operating in quasi-stable mode

    PubMed Central

    Strelkowa, Natalja; Barahona, Mauricio

    2010-01-01

    Ring topologies of repressing genes have qualitatively different long-term dynamics if the number of genes is odd (they oscillate) or even (they exhibit bistability). However, these attractors may not fully explain the observed behaviour in transient and stochastic environments such as the cell. We show here that even repressilators possess quasi-stable, travelling wave periodic solutions that are reachable, long-lived and robust to parameter changes. These solutions underlie the sustained oscillations observed in even rings in the stochastic regime, even if these circuits are expected to behave as switches. The existence of such solutions can also be exploited for control purposes: operation of the system around the quasi-stable orbit allows us to turn on and off the oscillations reliably and on demand. We illustrate these ideas with a simple protocol based on optical interference that can induce oscillations robustly both in the stochastic and deterministic regimes. PMID:20097721

  10. Encapsulated graphene field-effect transistors for air stable operation

    SciTech Connect

    Alexandrou, Konstantinos Kymissis, Ioannis; Petrone, Nicholas; Hone, James

    2015-03-16

    In this work, we report the fabrication of encapsulated graphene field effects transistors (GFETs) with excellent air stability operation in ambient environment. Graphene's 2D nature makes its electronics properties very sensitive to the surrounding environment, and thus, non-encapsulated graphene devices show extensive vulnerability due to unintentional hole doping from the presence of water molecules and oxygen limiting their performance and use in real world applications. Encapsulating GFETs with a thin layer of parylene-C and aluminum deposited on top of the exposed graphene channel area resulted in devices with excellent electrical performance stability for an extended period of time. Moisture penetration is reduced significantly and carrier mobility degraded substantially less when compared to non-encapsulated control devices. Our CMOS compatible encapsulation method minimizes the problems of environmental doping and lifetime performance degradation, enabling the operation of air stable devices for next generation graphene-based electronics.

  11. Stable top-up operation at SPring-8.

    PubMed

    Tanaka, Hitoshi; Adachi, Masatoshi; Aoki, Tsuyoshi; Asaka, Takao; Baron, Alfred; Daté, Shin; Fukami, Kenji; Furukawa, Yukito; Hanaki, Hirofumi; Hosoda, Naoyasu; Ishikawa, Tetsuya; Kimura, Hiroaki; Kobayashi, Kazuo; Kobayashi, Toshiaki; Kohara, Shinji; Kumagai, Noritaka; Masaki, Mitsuhiro; Masuda, Takemasa; Matsui, Sakuo; Mizuno, Akihiko; Nakamura, Takeshi; Nakatani, Takeshi; Noda, Takashi; Ohata, Toru; Ohkuma, Haruo; Ohshima, Takashi; Oishi, Masaya; Sasaki, Sigeki; Schimizu, Jun; Shoji, Masazumi; Soutome, Kouichi; Suzuki, Motohiro; Suzuki, Shinsuke; Suzuki, Yoshio; Takano, Shirou; Takao, Masaru; Takashima, Takeo; Takebe, Hideki; Takeuchi, Akihisa; Tamura, Kazuhiro; Tanaka, Ryotaro; Tanaka, Yoshihito; Taniuchi, Tsutomu; Taniuchi, Yukiko; Tsumaki, Kouji; Yamashita, Akihiro; Yanagida, Kenichi; Yoda, Yoshitaka; Yonehara, Hiroto; Yorita, Tetsuhiko; Yoshioka, Masamichi; Takata, Masaki

    2006-09-01

    Top-up operation allows SPring-8 to provide highly stable X-ray beams with arbitrary filling patterns. The implementation of top-up operation is described, with a focus on the simultaneous achievement of stability of stored current, beam orbit, purity of an isolated single bunch, and beam injection efficiency. Stored-current fluctuations have been routinely reduced to a level of 10(-3). Stored-beam oscillation on frequent beam injection, which was originally regarded as the most serious problem, has been successfully suppressed to a sufficiently low level that it never perturbs imaging experiments. Current impurities in nominally empty buckets have been reduced to a level of 10(-9) over more than one week of operation, making possible the measurement of time-resolved spectra using high-current bunches. Finally, excellent injection efficiency, higher than 80%, is routinely obtained, even for small undulator gaps, which is critical for preventing radiation damage to insertion-device magnets and to reduce leakage radiation. The process of achieving highly stabilized top-up operation at SPring-8 and its utility for user experiments are described. PMID:16924134

  12. Compact and stable temporally magnified tomography using a phase-locked broadband source.

    PubMed

    Li, Bowen; Wei, Xiaoming; Tan, Sisi; Kang, Jiqiang; Wong, Kenneth K Y

    2016-04-01

    The temporally magnified tomography system is further improved in terms of resolution and imaging stability. We simplify the system configuration and improve the axial resolution simultaneously by utilizing a stabilized all-fiber broadband source. The highly stable spectrum of the source assisted by a phase-locked loop guarantees an improved imaging quality. In addition, the impact of the repetition-rate fluctuation of the source to the system stability is analyzed, which also applies to other temporal imaging systems. Achieving a 90-μm in-air resolution at 89-MHz A-scan rate and improved stability, we are taking one major step toward the practical application of this new optical tomographic modality. PMID:27192287

  13. Stable isotope ratio analysis to differentiate temporal diets of a free-ranging herbivore.

    PubMed

    Walter, W D; Leslie, D M

    2009-07-01

    Stable isotope ratio analysis (SIRA) of carbon (delta13C) and nitrogen (delta15N) in tissue samples of herbivores can identify photosynthetic pathways (C3 vs. C4) of plants consumed. We present results from free-ranging Rocky Mountain elk (Cervus elaphus) that highlight the ability to differentiate diets using tissue delta13C and delta15N. The signatures of delta13C and delta15N differed in tissues of varying metabolic activity: muscle, a short-term dietary indicator (i.e., 1-2 months) and hoof, a long-term dietary indicator (i.e., 3-12 months). We also documented that delta13C and delta15N values along elk hooves (proximal, middle, distal sections) elucidated temporal shifts in dietary selection. The carbon isotopes of the composite hoof were similar to those of the middle section, but the composite hoof differed in delta(13)C from the distal and proximal sections. The delta13C and delta15N signatures also differed among elk populations, indicating temporal dietary shifts of individuals occupying disparate native range and human-derived agricultural landscapes. Analyses of stable isotopes in various tissues highlighted carbon and nitrogen assimilation through time and differences in the foraging ecology of a rangeland herbivore. PMID:19530151

  14. A spatio-temporal extension to the map cube operator

    NASA Astrophysics Data System (ADS)

    Alzate, Juan C.; Moreno, Francisco J.; Echeverri, Jaime

    2012-09-01

    OLAP (On Line Analytical Processing) is a set of techniques and operators to facilitate the data analysis usually stored in a data warehouse. In this paper, we extend the functionality of an OLAP operator known as Map Cube with the definition and incorporation of a function that allows the formulation of spatio-temporal queries. For example, consider a data warehouse about crimes that includes data about the places where the crimes were committed. Suppose we want to find and visualize the trajectory (a trajectory is just the path that an object follows through space as a function of time) of the crimes of a suspect beginning with his oldest crime and ending with his most recent one. In order to meet this requirement, we extend the Map Cube operator.

  15. Temporal variations in the stable carbon isotopic composition of methane emitted from Minnesota peatlands

    NASA Astrophysics Data System (ADS)

    Kelly, Cheryl A.; Dise, Nancy B.; Martens, Christopher S.

    1992-09-01

    The stable carbon isotopic composition of methane (δ13C) emitted from two peatland sites in the Marcell Experimental Forest in northern Minnesota was investigated during the snow-free season of 1989-1990. A seasonal range in δ13C values of 13‰ was seen for a forested bog with heavier (13C enriched) methane emitted during the wanner summer months. This shift was correlated with water table level suggesting control by microbial oxidation. Methane from a nearby poor fen transitional to bog dominated by Carex oligosperma showed a similar temporal trend but with a much smaller range of 5‰ during the same time period and with no water table level correlation. The methane emitted from the fen was consistently heavier than that emitted by the bog.

  16. Highly enhanced and temporally stable field emission from MWCNTs grown on aluminum coated silicon substrate

    SciTech Connect

    Sreekanth, M.; Ghosh, S. Patra, R.; Srivastava, P.

    2015-06-15

    In this work, a detailed field emission study of multi-walled carbon nanotubes (MWCNTs) grown on Si and Al coated Si substrates is reported. Morphological and microstructural studies of the films show higher entanglement of CNTs in the case of CNT/Si film as compared to CNT/Al/Si film. Raman studies show that the defect mediated peak (D) is substantially suppressed as compared to graphitic peak (G) resulting in significant reduction in I{sub D}/I{sub G} value in CNT/Al/Si film. Field emission (FE) current density of CNT/Al/Si film (∼25 mA/cm{sup 2}) is significantly higher as compared to that of CNT/Si film (∼1.6 mA/cm{sup 2}). A substantial improvement in temporal stability is also observed in CNT/Al/Si film. This enhancement in field emission current is attributed to strong adhesion between substrate and CNTs, low work function, high local field enhancement factor at the CNT tips and less entanglement of CNTs grown on Al/Si. The temporally stable CNT/Al/Si cold cathode can be a potential candidate to replace conventional electron sources in prototype devices.

  17. Highly enhanced and temporally stable field emission from MWCNTs grown on aluminum coated silicon substrate

    NASA Astrophysics Data System (ADS)

    Sreekanth, M.; Ghosh, S.; Patra, R.; Srivastava, P.

    2015-06-01

    In this work, a detailed field emission study of multi-walled carbon nanotubes (MWCNTs) grown on Si and Al coated Si substrates is reported. Morphological and microstructural studies of the films show higher entanglement of CNTs in the case of CNT/Si film as compared to CNT/Al/Si film. Raman studies show that the defect mediated peak (D) is substantially suppressed as compared to graphitic peak (G) resulting in significant reduction in ID/IG value in CNT/Al/Si film. Field emission (FE) current density of CNT/Al/Si film (˜25 mA/cm2) is significantly higher as compared to that of CNT/Si film (˜1.6 mA/cm2). A substantial improvement in temporal stability is also observed in CNT/Al/Si film. This enhancement in field emission current is attributed to strong adhesion between substrate and CNTs, low work function, high local field enhancement factor at the CNT tips and less entanglement of CNTs grown on Al/Si. The temporally stable CNT/Al/Si cold cathode can be a potential candidate to replace conventional electron sources in prototype devices.

  18. Stable Associations Masked by Temporal Variability in the Marine Copepod Microbiome

    PubMed Central

    Moisander, Pia H.; Sexton, Andrew D.; Daley, Meaghan C.

    2015-01-01

    Copepod-bacteria interactions include permanent and transient epi- and endobiotic associations that may play roles in copepod health, transfer of elements in the food web, and biogeochemical cycling. Microbiomes of three temperate copepod species (Acartia longiremis, Centropages hamatus, and Calanus finmarchicus) from the Gulf of Maine were investigated during the early summer season using high throughput amplicon sequencing. The most prominent stable component of the microbiome included several taxa within Gammaproteobacteria, with Pseudoalteromonas spp. especially abundant across copepod species. These Gammaproteobacteria appear to be promoted by the copepod association, likely benefitting from nutrient enriched microenvironments on copepods, and forming a more important part of the copepod-associated community than Vibrio spp. during the cold-water season in this temperate system. Taxon-specific associations included an elevated relative abundance of Piscirickettsiaceae and Colwelliaceae on Calanus, and Marinomonas sp. in Centropages. The communities in full and voided gut copepods had distinct characteristics, thus the presence of a food-associated microbiome was evident, including higher abundance of Rhodobacteraceae and chloroplast sequences in the transient communities. The observed variability was partially explained by collection date that may be linked to factors such as variable time since molting, gender differences, and changes in food availability and type over the study period. While some taxon-specific and stable associations were identified, temporal changes in environmental conditions, including food type, appear to be key in controlling the composition of bacterial communities associated with copepods in this temperate coastal system during the early summer. PMID:26393930

  19. Towards more stable operation of the Tokyo Tier2 center

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Mashimo, T.; Matsui, N.; Sakamoto, H.; Ueda, I.

    2014-06-01

    (Tokyo to New York and Tokyo to Los Angeles). The new line will be connected to LHCONE for the more improvement of the connectivity. In this circumstance, we are working for the further stable operation. For instance, we have newly introduced GPFS (IBM) for the non-grid disk storage, while Disk Pool Manager (DPM) are continued to be used as Tier2 disk storage from the previous system. Since the number of files stored in a DPM pool will be increased with increasing the total amount of data, the development of stable database configuration is one of the crucial issues as well as scalability. We have started some studies on the performance of asynchronous database replication so that we can take daily full backup. In this report, we would like to introduce several improvements in terms of the performances and stability of our new system and possibility of the further improvement of local I/O performance in the multi-core worker node. We also present the status of the wide area network connectivity from Japan to US and/or EU with LHCONE.

  20. Passive coherent combining of CEP-stable few-cycle pulses from a temporally divided hollow fiber compressor.

    PubMed

    Jacqmin, Hermance; Jullien, Aurélie; Mercier, Brigitte; Hanna, Marc; Druon, Frédéric; Papadopoulos, Dimitrios; Lopez-Martens, Rodrigo

    2015-03-01

    We demonstrate a simple and robust passive coherent combining technique for temporal compression of millijoule energy laser pulses down to few-cycle duration in a gas-filled hollow fiber. High combining efficiency is achieved by using carefully oriented calcite plates for temporal pulse division and recombination. Carrier-envelope phase (CEP)-stable, 6-fs, 800-nm pulses with more than 0.6 mJ energy are routinely generated. This method could aid in the energy scaling of CEP-stable hollow-fiber compressor systems. PMID:25723413

  1. Origin of temporally stable continuous-wave stokes emission in stimulated Brillouin scattering: evidence of spectral self-phase conjugation.

    PubMed

    Kovalev, Valeri I; Harrison, Robert G

    2005-12-15

    We report results on the appearance of temporally stable Stokes emission in stimulated Brillouin scattering (SBS) excited by continuous-wave pump radiation in optical fiber. With increasing pump strength the stable component emerges from stochastic emission slightly above the SBS threshold to become the dominant contribution, independent of fiber characteristics. These findings are shown to be a manifestation of spectral self-phase conjugation, providing what is to our knowledge the first experimental evidence of this phenomenon in optics. PMID:16389841

  2. Humans display a 'cooperative phenotype' that is domain general and temporally stable.

    PubMed

    Peysakhovich, Alexander; Nowak, Martin A; Rand, David G

    2014-01-01

    Understanding human cooperation is of major interest across the natural and social sciences. But it is unclear to what extent cooperation is actually a general concept. Most research on cooperation has implicitly assumed that a person's behaviour in one cooperative context is related to their behaviour in other settings, and at later times. However, there is little empirical evidence in support of this assumption. Here, we provide such evidence by collecting thousands of game decisions from over 1,400 individuals. A person's decisions in different cooperation games are correlated, as are those decisions and both self-report and real-effort measures of cooperation in non-game contexts. Equally strong correlations exist between cooperative decisions made an average of 124 days apart. Importantly, we find that cooperation is not correlated with norm-enforcing punishment or non-competitiveness. We conclude that there is a domain-general and temporally stable inclination towards paying costs to benefit others, which we dub the 'cooperative phenotype'. PMID:25225950

  3. Alaska peninsula stable isotope and radioisotope chemistry: a study in temporal and adaptive diversity.

    PubMed

    Coltrain, Joan Brenner

    2010-12-01

    Purified bone collagen from a small suite of human remains recovered at three sites on the Alaska Peninsula (Port Moller, Brooks River, and Mink Island) were analyzed for stable carbon and nitrogen isotope chemistry and were accelerator radiocarbon dated. Because samples sizes were small and faunal isotope chemistry lacking, results should be considered preliminary. However, these data indicate that each locality was represented by a somewhat different suite of subsistence strategies and covered a distinct temporal span. Port Moller burials (n = 7) from the Hot Springs site date to a calibrated 2σ range of 3547-1388 BP. Although marine foods clearly made the greatest contribution to these diets, individuals were not as heavily reliant on high-trophic-level marine taxa as eastern Aleutian groups to the west, given their intake of salmon and evidence of caribou hunting. Brooks River burials (n = 9) expressed an inland foraging focus with significant reliance on caribou and spawning salmon and covered a calibrated 2σ range of 1484-381 BP. In contrast, individuals from Mink Island (n = 7), dating to cal. 666-292 BP, were heavily reliant on high-trophic-level marine prey similar to but not as enriched isotopically as the Aleut, perhaps a consequence of limited access to caribou and greater reliance on invertebrates. This pattern suggests that prehistoric economic strategies on the Alaska Peninsula were diverse, characterized by fine-tuned adaptations to local ecological settings, perhaps mediated by ethnic factors and territorial and social pressures. PMID:21417886

  4. Mimicking nature by codelivery of stimulant and inhibitor to create temporally stable and spatially restricted angiogenic zones

    PubMed Central

    Yuen, William W.; Du, Nan R.; Chan, Chun H.; Silva, Eduardo A.; Mooney, David J.

    2010-01-01

    Nature frequently utilizes opposing factors to create a stable activator gradient to robustly control pattern formation. This study employs a biomimicry approach, by delivery of both angiogenic and antiangiogenic factors from spatially restricted zones of a synthetic polymer to achieve temporally stable and spatially restricted angiogenic zones in vivo. The simultaneous release of the two spatially separated agents leads to a spatially sharp angiogenic region that is sustained over 3 wk. Further, the contradictory action of the two agents leads to a stable level of proangiogenic stimulation in this region, in spite of significant variations in the individual release rates over time. The resulting spatially restrictive and temporally sustained profiles of active signaling allow the creation of a spatially heterogeneous and functional vasculature. PMID:20921366

  5. Temporal and Spatial Variation of Surface Water Stable Isotopes in the Marys River Basin, Oregon

    NASA Astrophysics Data System (ADS)

    Nickolas, L. B.; Segura, C.; Brooks, J. R.

    2015-12-01

    Understanding the temporal and spatial variability of water sources within a basin is vital to our ability to manage the impacts of climate variability and land cover change. Water stable isotopes can be used as a tool to determine geographic and seasonal sources of water at the basin scale. Previous studies in the Coastal Range of Oregon reported that the variation in the isotopic signatures of surface water does not conform to the commonly observed "rainout effect", which exhibits a trend of increasing isotopic depletion with rising elevation. The primary purpose of this research is to investigate the mechanisms governing seasonal and spatial variations in the isotopic signature of surface waters within the Marys River Basin, located in the Oregon Coastal Range. We hypothesize that catchment orientation, drainage area, geology, and topography act as controlling factors on groundwater flow, storage, and atmospheric moisture cycling, which explain variations in source water contribution. Surface water and precipitation samples were collected every 2-3 weeks for isotopic analysis of δ18O and δ2H for one year. Preliminary results indicate a significant difference (p<0.001) in isotopic signature between watersheds underlain by basalt and sandstone. The degree of separation is the most distinct during the summer when low flows likely reflect deeper groundwater sources, whereas isotopic signatures during the rainy season (fall & winter) show a greater degree of similarity between the two lithologies. These findings indicate that the more permeable sandstone formations may be hydrologically connected to enriched water sources on the windward side of the Coastal Range that sustain baseflow within catchments on the leeward side, while streams draining basalt catchments are fed by a more depleted source of water (e.g. precipitation originating within the Marys River Basin).

  6. Temporal characterization of bacteria in hayrings serving as stable fly larval development sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae) are important pests of pastured cattle, reducing weight gains, and causing discomfort to the animals. The focus of stable fly control has historically been on preventing adult stable flies from biting cattle. While the adult files biting t...

  7. Spatial-temporal changes in Andean plateau climate and elevation from stable isotopes of mammal teeth

    NASA Astrophysics Data System (ADS)

    Bershaw, John; Garzione, Carmala N.; Higgins, Pennilyn; MacFadden, Bruce J.; Anaya, Frederico; Alvarenga, Herculano

    2010-01-01

    Paleoelevation constraints from fossil leaf physiognomy and stable isotopes of sedimentary carbonate suggest that significant surface uplift of the northern Andean plateau, on the order of 2.5 ± 1 km, occurred between ˜ 10.3 and 6.4 Ma. Independent spatial and temporal constraints on paleoelevation and paleoclimate of both the northern and southern plateau are important for understanding the distribution of rapid surface uplift and its relation to climate evolution across the plateau. This study focuses on teeth from modern and extinct mammal taxa (including notoungulates, pyrotheres, and litopterns) spanning ˜ 29 Ma to present, collected from the Altiplano and Eastern Cordillera of Bolivia (16.2°S to 21.4°S), and lowland Brazil. Tooth enamel of large, water-dependent mammals preserves a record of surface water isotopes and the type of plants that animals ingested while their teeth were mineralizing. Previous studies have shown that the δ18O of modern precipitation and surface waters decrease systematically with increasing elevations across the central Andes. Our results from high elevation sites between 3600 and 4100 m show substantially more positive δ18O values for late Oligocene tooth samples compared to < 10 Ma tooth δ18O values. Late Oligocene teeth collected from low elevation sites in southeast Brazil show δ18O values similar (within 2‰) to contemporaneous teeth collected at high elevation in the Eastern Cordillera. This affirms that the Andean plateau was at a very low elevation during the late Oligocene. Late Oligocene teeth from the northern Eastern Cordillera also yield consistent δ13C values of about - 9‰, indicating that the environment was semi-arid at that time. Latitudinal gradients in δ18O values of late Miocene to Pliocene fossil teeth are similar to modern values for large mammals, suggesting that by ˜ 8 Ma in the northern Altiplano and by ˜ 3.6 Ma in the southern Altiplano, both regions had reached high elevation and

  8. Temporal logic and operation relations based knowledge representation for land cover change web services

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Wu, Hao; Li, Songnian; Liao, Anping; He, Chaoying; Peng, Shu

    2013-09-01

    Providing land cover spatio-temporal information and geo-computing through web service is a new challenge for supporting global change research, earth system simulation and many other societal benefit areas. This requires an integrated knowledge representation and web implementation of static land cover and change information, as well as the related operations for geo-computing. The temporal logic relations among land cover snapshots and increments were examined with a matrix-based three-step analysis. Twelve temporal logic relations were identified and five basic spatial operations were formalized with set operators, which were all used to develop algorithms for deriving implicit change information. A knowledge representation for land cover change information was then developed based on these temporal logic and operation relations. A prototype web-service system was further implemented based on OWL-DL. Both online access and conversion of land cover spatio-temporal information can be facilitated with such a web service system.

  9. Application Of Stable Isotope Analysis To Study Temporal Changes In Foraging Ecology In A Highly Endangered Amphibian

    PubMed Central

    Gillespie, J. Hayley

    2013-01-01

    Background Understanding dietary trends for endangered species may be essential to assessing the effects of ecological disturbances such as habitat modification, species introductions or global climate change. Documenting temporal variation in prey selection may also be crucial for understanding population dynamics. However, the rarity, secretive behaviours and obscure microhabitats of some endangered species can make direct foraging observations difficult or impossible. Furthermore, the lethality or invasiveness of some traditional methods of dietary analysis (e.g. gut contents analysis, gastric lavage) makes them inappropriate for such species. Stable isotope analysis facilitates non-lethal, indirect analysis of animal diet that has unrealized potential in the conservation of endangered organisms, particularly amphibians. Methodology/findings I determined proportional contributions of aquatic macroinvertebrate prey to the diet of an endangered aquatic salamander Eurycea sosorum over a two-year period using stable isotope analysis of 13/12C and 15/14N and the Bayesian stable isotope mixing model SIAR. I calculated Strauss’ dietary electivity indices by comparing these proportions with changing relative abundance of potential prey species through time. Stable isotope analyses revealed that a previously unknown prey item (soft-bodied planarian flatworms in the genus Dugesia) made up the majority of E. sosorum diet. Results also demonstrate that E. sosorum is an opportunistic forager capable of diet switching to include a greater proportion of alternative prey when Dugesia populations decline. There is also evidence of intra-population dietary variation. Conclusions/significance Effective application of stable isotope analysis can help circumvent two key limitations commonly experienced by researchers of endangered species: the inability to directly observe these species in nature and the invasiveness or lethality of traditional methods of dietary analysis. This

  10. Stable isotopes in river waters in the Tajik Pamirs: regional and temporal characteristics.

    PubMed

    Meier, Christiane; Knoche, Malte; Merz, Ralf; Weise, Stephan M

    2013-01-01

    The Gunt River catchment in the Central Pamirs is a representative of the headwater catchments of the Aral Sea Basin. It covers 14,000 km(2), spanning altitudes between 2000 and 6700 m a.s.l. In a monitoring network, water samples were taken at 30 sampling points every month and analysed for the stable water isotopes ((18)O and (2)H). Our first results show δ(2)H values in the range from-131.2 to-94.9 ‰ and δ(18)O values from-18.0 to-14.0 ‰. The stable isotope patterns in the catchment seem to follow a systematic way, dominated by an altitude effect with a mean Δ δ(2)H=-3.6 ‰/100 m. The observed seasonal variations can be explained by geographical aspects such as the influence of different wind systems as well as melting processes. PMID:24313375

  11. Spatial and temporal analysis of stable isotopes in tap water across China

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Hu, H.; Tian, F.; Tie, Q.

    2015-12-01

    Stable isotopes in water (δ2H and δ18O) are important indicators of hydrological and ecological pattern and process. Water isotopes have been used to trace atmospheric moisture source, identify source of groundwater and surface water charge, reconstruct paleoclimate, and so on. Tap water appears to reflect pervasive features of regional integrated hydrological process. China is a large-size country with high variations in both environmental and geographical factors including temperature, precipitation amount, relative humidity, latitude, altitude et al. Here we present a first national-scale survey on stable isotope of tap water across China. More than 1000 tap water samples have been collected from 93 cities across China by monthly between December 2014 and November 2015. Stable isotope composition of tap water ranged from -132.1‰ to -25.6‰ (δ2H) and from -17.5‰ to -4.2‰ (δ18O). The Meteoric Water Line is δ2H = 7.77 δ18O + 5.79 (r2 = 0.95) and the LMWL of Chinese precipitation is δ2H =7.6δ18O+ 9.94 (r2= 0.97). Spatial distribution of stable isotopes present typical "continental effect", isotope values generally decrease from coastal regions to inland. Isotopes in different regions present different correlations with temperature, precipitation amount, latitude and altitude as a result of varied moisture source and local water supply. The results of the study could provide mapping information of tap water for fundamental isotope hydrological studies in different regions of China.

  12. Temporal variation in mycorrhizal diversity and carbon and nitrogen stable isotope abundance in the wintergreen meadow orchid Anacamptis morio.

    PubMed

    Ercole, Enrico; Adamo, Martino; Rodda, Michele; Gebauer, Gerhard; Girlanda, Mariangela; Perotto, Silvia

    2015-02-01

    Many adult orchids, especially photoautotrophic species, associate with a diverse range of mycorrhizal fungi, but little is known about the temporal changes that might occur in the diversity and functioning of orchid mycorrhiza during vegetative and reproductive plant growth. Temporal variations in the spectrum of mycorrhizal fungi and in stable isotope natural abundance were investigated in adult plants of Anacamptis morio, a wintergreen meadow orchid. Anacamptis morio associated with mycorrhizal fungi belonging to Tulasnella, Ceratobasidium and a clade of Pezizaceae (Ascomycetes). When a complete growing season was investigated, multivariate analyses indicated significant differences in the mycorrhizal fungal community. Among fungi identified from manually isolated pelotons, Tulasnella was more common in autumn and winter, the pezizacean clade was very frequent in spring, and Ceratobasidium was more frequent in summer. By contrast, relatively small variations were found in carbon (C) and nitrogen (N) stable isotope natural abundance, A. morio samples showing similar (15)N enrichment and (13)C depletion at the different sampling times. These observations suggest that, irrespective of differences in the seasonal environmental conditions, the plant phenological stages and the associated fungi, the isotopic content in mycorrhizal A. morio remains fairly constant over time. PMID:25382295

  13. Nonlinear theory of stable, efficient operation of a gyrotron at cyclotron harmonics

    NASA Astrophysics Data System (ADS)

    Saraph, G. P.; Antonsen, T. M., Jr.; Nusinovich, G. S.; Levush, B.

    1993-12-01

    One of the main obstacles in achieving stable, efficient operation at the cyclotron harmonics in a gyrotron is mode competition with parasitic modes at the fundamental frequency. In this article, the nonlinear dynamics of mode interactions in such a system are studied using a multifrequency, time-dependent model. The results of numerical simulations for a second harmonic gyrotron are presented by considering two starting scenarios: (a) fast voltage rise or an instant turn-on case, and (b) slow voltage rise case. For the first case, it is demonstrated that for a certain range of operating parameters, the presence of a parasitic mode at the fundamental can be helpful in the excitation of the second harmonic operating mode. In the second case, it is found that the unstable operating region increases with the value of the rise time constant of the electrode voltages. Stable, efficient gyrotron operation at the second harmonic is demonstrated using the numerical study.

  14. Note: A new regulation method of stable operation of high power cathode ion source

    SciTech Connect

    Jiang, C. C.; Xie, Y. H. Hu, C. D.; Xie, Y. L.; Liu, S.; Liang, L. Z.; Liu, Z. M.

    2015-05-15

    The hot cathode ion source will tend to be unstable when operated with high power and long pulse. In order to achieve stable operation, a new regulation method based on the arc power (discharge power) feedback control was designed and tested on the hot cathode ion source test bed with arc discharge and beam extraction. The results show that the new regulation method can achieve stable arc discharge and beam extraction. It verifies the success of feedback control of arc source with arc power.

  15. Spatial and temporal characteristics of stable isotopes in the Tarim River Basin.

    PubMed

    Sun, Congjian; Li, Xingong; Chen, Yaning; Li, Weihong; Stotler, Randy L; Zhang, Yongqing

    2016-06-01

    By using 233 isotope samples, we investigated the spatial and temporal variations of δ(18)O and δ(2)H in precipitation and surface water, and the contribution of different water sources in the rivers within the Tarim River Basin (TRB), which receives snow/glacier meltwater, groundwater, and rainfall. Our study revealed a similar seasonal pattern of precipitation δ(18)O and δ(2)H at both the north and south edges of the basin, indicating the dominant effect of westerly air masses in the summer and the combined influence of westerly and polar air masses during the winter, although the southern part showed more complex precipitation processes in the summer. River water in the basin has relatively large temporal variations in both δ(18)O and δ(2)H showing a distinct seasonal pattern with lower isotope values in May than in September. Higher d-excess values throughout the year in the Aksu river and the Tizinafu river suggest that water may be intensively recycled in the mountains of the TRB. Based on isotopic hydrograph separation, we found that groundwater is the main water source that discharges the entire basin although individual rivers vary. PMID:26862902

  16. Guthrie card methylomics identifies temporally stable epialleles that are present at birth in humans.

    PubMed

    Beyan, Huriya; Down, Thomas A; Ramagopalan, Sreeram V; Uvebrant, Kristina; Nilsson, Anita; Holland, Michelle L; Gemma, Carolina; Giovannoni, Gavin; Boehm, Bernhard O; Ebers, George C; Lernmark, Åke; Cilio, Corrado M; Leslie, R David; Rakyan, Vardhman K

    2012-11-01

    A major concern in common disease epigenomics is distinguishing causal from consequential epigenetic variation. One means of addressing this issue is to identify the temporal origins of epigenetic variants via longitudinal analyses. However, prospective birth-cohort studies are expensive and time consuming. Here, we report DNA methylomics of archived Guthrie cards for the retrospective longitudinal analyses of in-utero-derived DNA methylation variation. We first validate two methodologies for generating comprehensive DNA methylomes from Guthrie cards. Then, using an integrated epigenomic/genomic analysis of Guthrie cards and follow-up samplings, we identify interindividual DNA methylation variation that is present both at birth and 3 yr later. These findings suggest that disease-relevant epigenetic variation could be detected at birth, i.e., before overt clinical disease. Guthrie card methylomics offers a potentially powerful and cost-effective strategy for studying the dynamics of interindividual epigenomic variation in a range of common human diseases. PMID:22919074

  17. Stable isotope analysis of temporal variation in the diets of pre-fledged Laughing Gulls

    USGS Publications Warehouse

    Knoff, A.J.; Macko, S.A.; Erwin, R.M.; Brown, K.M.

    2002-01-01

    The *13C, *15N, and *34S stable isotopic values of feathers from pre-fledged Laughing Gulls (Larus atricilla) in coastal Virginia and Jamaica Bay, New York were used to examine dietary variation during the nestling period. The tip portions of the feathers were used to indicate diet during the initiation of primary feather growth, whereas the base portions indicated diet during the period immediately prior to fledging. The results indicate that diets of the nestlings in Virginia moved to a higher trophic level during the period prior to fledging, however the New York nestlings did not appear to undergo any appreciable dietary change during this period. Overall, nestlings from both colonies consumed proportionately more foods of marine origin than freshwater or terrestrial. Therefore, the results do not support those of earlier studies that suggested that partially developed salt glands in young gulls might restrict the diet to more terrestrial or freshwater prey in the early stages of nestling growth.

  18. Remotely operated compact underwater temporally encoded imager: CUTEI

    NASA Astrophysics Data System (ADS)

    Alley, Derek; Cochenour, Brandon; Mullen, Linda

    2016-05-01

    Remotely operated vehicles (ROVs) typically use traditional optical imaging systems, such as cameras, for high resolution imaging. Cameras are effective in clear water, but have extremely poor performance in degraded visual environments (DVEs) such as turbid coastal waters and harbors. This is due to the multiple scattering of the light from the particulates and organic matter in the water. Laser-based sensors have been developed to enhance optical imaging in DVEs1,3,4,5,6. However, since conventional approaches require that the illuminator and receiver be located on the same platform, the size, weight, and power (SWaP) requirements are incompatible with small ROVs. Researchers at NAVAIR have developed a low cost optical imager utilizing a bistatic geometry where the illuminator and receiver are mounted on separate, smaller platforms. The illuminator steers a modulated laser beam with a microelectromechanical system (MEMS) scanner to sequentially illuminate an underwater object. A distant receiver collects the object reflected laser light and reconstructs the imagery. Communications information, including a synchronization sequence, is encoded onto the modulation which is used by the receiver to build the image. The SWaP of the illuminator's components have been optimized and integrated into a modified version of the OpenROV, a miniature, commercial off-the-shelf ROV. This paper reports on the efforts to reduce the SWaP of the modulated illuminator and the results of testing this system in a laboratory water tank environment.

  19. Food web structure of sandy beaches: Temporal and spatial variation using stable isotope analysis

    NASA Astrophysics Data System (ADS)

    Bergamino, Leandro; Lercari, Diego; Defeo, Omar

    2011-03-01

    The food web structure of two sandy beach ecosystems with contrasting morphodynamics (dissipative vs. reflective) was examined using stable carbon (δ 13C) and nitrogen (δ 15N) isotope analysis. Organic matter sources (POM: particulate organic matter; SOM: sediment organic matter) and consumers (zooplankton, benthic invertebrates and fishes) were sampled seasonally in both sandy beaches. Food webs significantly differed between beaches: even though both webs were mainly supported by POM, depleted δ 13C and δ 15N values for food sources and consumers were found in the dissipative system (following the reverse pattern in δ 13C values for consumers) for all the four seasons. Primary consumers (zooplankton and benthic invertebrates) use different organic matter sources on each beach and these differences are propagated up in the food web. The higher productivity found in the dissipative beach provided a significant amount of food for primary consumers, notably suspension feeders. Thus, the dissipative beach supported a more complex food web with more trophic links and a higher number of prey and top predators than the reflective beach. Morphodynamic factors could explain the contrasting differences in food web structure. The high degree of retention (nutrients and phytoplankton) recorded for the surf zone of the dissipative beach would result in the renewed accumulation of POM that sustains a more diverse and richer fauna than the reflective beach. Further studies directed to assess connections between the macroscopic food web, the surf-zone microbial loop and the interstitial compartment will provide a deeper understanding on the functioning of sandy beach ecosystems.

  20. Assessing site-specific spatio-temporal variations in hydrogen and oxygen stable isotopes of human drinking water

    NASA Astrophysics Data System (ADS)

    Kennedy, C. D.; Bowen, G. J.; Ehleringer, J. R.

    2008-12-01

    Stable isotope ratios of hydrogen and oxygen (δ2H and δ18O) are environmental forensic tracers that can be used to constrain the origin and movement of animals, people, and products. The fundamental assumption underlying this method is that water resources at different geographic locations have distinct and characteristic isotopic signatures that are assimilated into organic tissues. Although much is known about regional-scale spatio-temporal variability in δ2H and δ18O of water, few studies have addressed the question of how distinct these geographic and seasonal patterns are for any given site. To address this question, a 2-year survey of δ2H and δ18O in tap water from across the contiguous U.S. and Canada was conducted. The data show that seasonal variability in δ2H and δ18O of tap water is generally low (<10 ‰ for δ2H), and those with the highest variability can be classified as: a) cities or towns in areas of high climate seasonality, or b) large cities in arid or seasonally arid regions which access and switch among multiple water sources throughout the year. The data suggest that inter-annual variation in tap water isotope ratios is typically low, with a median difference for month-month pairs during the 2 sampling years of 2.7 (δ2H). The results from this study confirm the existence of temporal variability in δ2H and δ18O of tap water, but suggest that this variability in human-managed systems is highly damped and may be amenable to classification, modeling, and prediction. In all, the data provide the foundation for incorporating temporal variation in predictive models of water and organic δ2H and δ18O, leading to more robust and statistically defensible tests of geographic origin.

  1. Temporal variation of nitrogen balance within constructed wetlands treating slightly polluted water using a stable nitrogen isotope experiment.

    PubMed

    Zhang, Wanguang; Lei, Qiongye; Li, Zhengkui; Han, Huayang

    2016-02-01

    Slightly polluted water has become one of the main sources of nitrogen contaminants in recent years, for which constructed wetlands (CW) is a typical and efficient treatment. However, the knowledge about contribution of individual nitrogen removal pathways and nitrogen balance in constructed wetlands is still limited. In this study, a stable-isotope-addition experiment was performed in laboratory-scale constructed wetlands treating slightly polluted water to determine quantitative contribution of different pathways and temporal variation of nitrogen balance using Na(15)NO3 as tracer. Microbial conversion and substrate retention were found to be the dominant pathways in nitrogen removal contributing 24.4-79.9 and 8.9-70.7 %, respectively, while plant contributed only 4.6-11.1 % through direct assimilation but promoted the efficiency of other pathways. In addition, microbial conversion became the major way to remove N whereas nitrogen retained in substrate at first was gradually released to be utilized by microbes and plants over time. The findings indicated that N2 emission representing microbial conversion was not only the major but also permanent nitrogen removal process, thus keeping a high efficiency of microbial conversion is important for stable and efficient nitrogen removal in constructed wetlands. PMID:26438366

  2. 18-Months operation of Lunar-based Ultraviolet Telescope: a highly stable photometric performance

    NASA Astrophysics Data System (ADS)

    Wang, J.; Meng, X. M.; Han, X. H.; Cai, H. B.; Cao, L.; Deng, J. S.; Qiu, Y. L.; Wang, S.; Wei, J. Y.; Hu, J. Y.

    2015-11-01

    We here report the photometric performance of Lunar-based Ultraviolet telescope (LUT), the first robotic telescope working on the Moon, for its 18-months operation. In total, 17 IUE standards have been observed in 51 runs until June 2015, which returns a highly stable photometric performance during the past 18 months (i.e., no evolution of photometric performance with time). The magnitude zero point is determined to be 17.53±0.05 {mag}, which is not only highly consistent with the results based on its first 6-months operation, but also independent on the spectral type of the standard from which the magnitude zero point is determined. The implications of this stable performance is discussed, and is useful for next generation lunar-based astronomical observations.

  3. Stable Artificial Dissipation Operators for Finite Volume Schemes on Unstructured Grids

    NASA Technical Reports Server (NTRS)

    Svard, Magnus; Gong, Jing; Nordstrom, Jan

    2006-01-01

    Our objective is to derive stable first-, second- and fourth-order artificial dissipation operators for node based finite volume schemes. Of particular interest are general unstructured grids where the strength of the finite volume method is fully utilized. A commonly used finite volume approximation of the Laplacian will be the basis in the construction of the artificial dissipation. Both a homogeneous dissipation acting in all directions with equal strength and a modification that allows different amount of dissipation in different directions are derived. Stability and accuracy of the new operators are proved and the theoretical results are supported by numerical computations.

  4. Highly Stable Operation of Metal Oxide Nanowire Transistors in Ambient Humidity, Water, Blood, and Oxygen.

    PubMed

    Lim, Taekyung; Bong, Jihye; Mills, Edmund M; Kim, Sangtae; Ju, Sanghyun

    2015-08-01

    The capability for robust operation of nanoscale transistors under harsh environments is equally important as their operating parameters such as high on-currents, high mobility, and high sensing selectivity. For electronic/biomedical applications, in particular, transistor operation must be stable under diverse conditions including ambient humidity, water, blood, and oxygen. Here we demonstrate the use of a self-assembled monolayer of octadecylphosphonic acid (OD-PA) to passivate a functionalized nanowire transistor, allowing the device to operate consistently in such environments. In contrast, without passivation, the characteristics (especially the threshold voltage) of identical nanowire transistors were dramatically altered under these conditions. Furthermore, the OD-PA-passivated transistor shows no signs of long-term stability deterioration and maintains equally high sensing selectivity to light under the harsh environments because of OD-PA's optical transparency. These results demonstrate the suitability of OD-PA passivation methods for fabricating commercial nanoelectronics. PMID:26200320

  5. Experimental evaluation of stable long term operation of semiconductor magnetic sensors at ITER relevant environment

    NASA Astrophysics Data System (ADS)

    Bolshakova, I.; Belyaev, S.; Bulavin, M.; Brudnyi, V.; Chekanov, V.; Coccorese, V.; Duran, I.; Gerasimov, S.; Holyaka, R.; Kargin, N.; Konopleva, R.; Kost, Ya.; Kuech, T.; Kulikov, S.; Makido, O.; Moreau, Ph; Murari, A.; Quercia, A.; Shurygin, F.; Strikhanov, M.; Timoshyn, S.; Vasil'evskii, I.; Vinichenko, A.

    2015-08-01

    The paper deals with radiation resistant sensors and their associated measuring instrumentation developed in the course of R and D activities carried out in the framework of an international collaboration. The first trial tests of three-dimensional (3D) probes with Hall sensors have been performed in European tokamaks TORE SUPRA (2004) and JET (2005). Later in 2009 six sets of 3D probes were installed in JET and now continue to operate. The statistical analysis performed in 2014 on the basis of the JET database have demonstrated stable long term operation of all 18 sensors of 3D probes. The results of measurements conducted at the neutron fluxes of nuclear reactors have demonstrated the operability of the sensors up to high neutron fluences of F  >  1018n • cm-2 that exceeds the maximum one for the locations of steady state sensors in ITER over its total lifetime.

  6. Temporal evolution of stable water isotopologues in cloud droplets in a hill cap cloud in central Europe (HCCT-2010)

    USGS Publications Warehouse

    Spiegel, J.K.; Aemisegger, F.; Scholl, M.; Wienhold, F.G.; Collett, J.L., Jr.; Lee, T.; van Pinxteren, D.; Mertes, S.; Tilgner, A.; Herrmann, H.; Werner, Roland A.; Buchmann, N.; Eugster, W.

    2012-01-01

    In this work, we present the first study resolving the temporal evolution of δ2H and δ18O values in cloud droplets during 13 different cloud events. The cloud events were probed on a 937 m high mountain chain in Germany in the framework of the Hill Cap Cloud Thuringia 2010 campaign (HCCT-2010) in September and October 2010. The δ values of cloud droplets ranged from −77‰ to −15‰ (δ2H) and from −12.1‰ to −3.9‰ (δ18O) over the whole campaign. The cloud water line of the measured δ values was δ2H=7.8×δ18O+13×10−3, which is of similar slope, but with higher deuterium excess than other Central European Meteoric Water Lines. Decreasing δ values in the course of the campaign agree with seasonal trends observed in rain in central Europe. The deuterium excess was higher in clouds developing after recent precipitation revealing episodes of regional moisture recycling. The variations in δ values during one cloud event could either result from changes in meteorological conditions during condensation or from variations in the δ values of the water vapor feeding the cloud. To test which of both aspects dominated during the investigated cloud events, we modeled the variation in δ values in cloud water using a closed box model. We could show that the variation in δ values of two cloud events was mainly due to changes in local temperature conditions. For the other eleven cloud events, the variation was most likely caused by changes in the isotopic composition of the advected and entrained vapor. Frontal passages during two of the latter cloud events led to the strongest temporal changes in both δ2H (≈ 6‰ per hour) and δ18O (≈ 0.6‰ per hour). Moreover, a detailed trajectory analysis for the two longest cloud events revealed that variations in the entrained vapor were most likely related to rain out or changes in relative humidity and temperature at the moisture source region or both. This study illustrates the sensitivity of stable isotope

  7. High voltage threshold for stable operation in a dc electron gun

    NASA Astrophysics Data System (ADS)

    Yamamoto, Masahiro; Nishimori, Nobuyuki

    2016-07-01

    We report clear observation of a high voltage (HV) threshold for stable operation in a dc electron gun. The HV hold-off time without any discharge is longer than many hours for operation below the threshold, while it is roughly 10 min above the threshold. The HV threshold corresponds to the minimum voltage where discharge ceases. The threshold increases with the number of discharges during HV conditioning of the gun. Above the threshold, the amount of gas desorption per discharge increases linearly with the voltage difference from the threshold. The present experimental observations can be explained by an avalanche discharge model based on the interplay between electron stimulated desorption (ESD) from the anode surface and subsequent secondary electron emission from the cathode by the impact of ionic components of the ESD molecules or atoms.

  8. Non-operative Treatment Outcomes of Stable Juvenile Osteochondritis Dissecans Lesions of the Knee

    PubMed Central

    Tepolt, Frances; Heyworth, Benton E.; Kocher, Mininder S.

    2016-01-01

    Objectives: Osteochondritis dissecans (OCD) of the knee most commonly occurs in skeletally-immature pre-adolescent or adolescent patients. Stable juvenile OCD lesions are initially treated via non-operative methods, with varying rates of successful healing reported in the literature. Unloader bracing has been introduced as a relatively new method designed to reduce weight-bearing stress and promote healing for femoral condyle lesions, although the outcomes of unloader bracing compared to other forms of non-operative treatment have not been established. Methods: A retrospective case series was designed to include all patients initially treated non-operatively for stable juvenile OCD of the femoral condyle at a single institution from 2002-2014. Following IRB approval, patient medical records were reviewed for demographic and clinical data, including symptom duration, prior conservative treatment, non-operative treatment modality prescribed and clinical outcome. Results: 223 knees of 196 patients (146/196 (74%) male) underwent non-operative treatment for stable OCD of the medial or lateral femoral condyle. Mean age at presentation 11.5 +/- 1.7 years (range 6-16 years). 27/196 patients (14%) were diagnosed with bilateral OCD at presentation, while 169/196 (86%) presented with unilateral OCD. 180/223 knees (81%) were medial femoral condyle lesions, while 39/223 (17%) were lateral femoral condyle lesions and 4/223 (2%) bicondylar. Reported symptom duration was 10.4 +/- 8.8 months (range 0.1 - 38 months). 222/223 (99.6%) knees presented with knee pain, 68/223 (30%) with one or more mechanical symptoms (swelling, giving-way, locking, clicking). 87/223 (39%) had undergone previous non-operative treatment for an average of 2.1 months. On exam at presentation, 130/223 (58%) had tenderness to palpation noted over the associated femoral condyle or ipsilateral joint line. Treatment was based on physician preference. 121/223 (54%) were treated with unloader bracing with activity

  9. Stable mode-locking operation in a Cr:forsterite laser with a five-mirror cavity.

    PubMed

    Miura, T; Kobayashi, K; Zhang, Z; Torizuka, K; Kannari, F

    1999-04-15

    The experimental finding of more-stable mode-locking operation in a five-mirror cavity than in a conventional four-mirror cavity for a Cr:forsterite laser [IEEE J. Quantum Electron. 33, 1975 (1997)] was interpreted by ABCD-matrix formalism. Since the optimum cavity configuration operation for mode-locking operation was attainable in the middle of the stable cavity condition, we conclude that one can easily achieve KLM alignment and stable mode locking with a five-mirror cavity. PMID:18071570

  10. Temporal dynamics in a shallow coastal benthic food web: Insights from fatty acid biomarkers and their stable isotopes.

    PubMed

    Braeckman, Ulrike; Provoost, Pieter; Sabbe, Koen; Soetaert, Karline; Middelburg, Jack J; Vincx, Magda; Vanaverbeke, Jan

    2015-07-01

    We investigated the temporal variation of pelagic and benthic food sources in the diet of benthic taxa at a depositional site in the Southern Bight of the North Sea by means of fatty acid (FA) biomarkers and compound-specific stable isotope analysis (CSIA). The taxa were the non-selective deposit feeding nematodes (Sabatieria spp. and 'other nematodes'), and three dominant macrobenthic species: two true suspension-deposit feeders (the bivalve Abra alba and the tube dwelling polychaete Owenia fusiformis) and the suspected predatory mud-dwelling anemone Sagartia sp. These species make up on average 16% (Abra alba), 17% (Sagartia sp.) and 20% (Owenia fusiformis) of the biomass in the Abra alba-Kurtiella bidentata community in this area. Phytoplankton dynamics in the suspended particulate matter of the water column as inferred from cell counts, chlorophyll-a and organic carbon content were clearly visible in sediment and animal FA abundance as well, whereas phytodetritus dynamics in the sediment FA composition were less clear, probably due to patchy distribution or stripping of FA by macrofauna. Nematodes appeared to assimilate mainly Polyunsaturated Fatty Acids (PUFAs) from their sedimentary environment and were further non-selectively accumulating more (Sabatieria spp.) or less ('other nematodes') FA from the deposited phytodetritus. In contrast, Abra alba FA composition was consistent with a diatom-dominated diet and consumption of Phaeocystis was observed in Owenia fusiformis, whereas Sagartia sp. showed evidence of a predatory behaviour. While the total FA content in Owenia fusiformis remained constant throughout the year, Sagartia sp. doubled and Abra alba increased its FA level more than 10-fold in response to the organic matter deposition from the phytoplankton bloom. This leads to the conclusion that there is no resource partitioning between non-selective deposit feeding nematodes and the suspension-deposit feeding macrobenthic organisms, suggesting they

  11. Temporal variability in Chemical and Stable isotopic characteristics of ambient bulk aerosols over a coastal environment of India

    NASA Astrophysics Data System (ADS)

    Agnihotri, R.; Karapurkar, S. G.; Sarma, V. V.; Praveen, P.; Kumar, M. D.

    2012-12-01

    Atmospheric carbonaceous aerosols are known to influence regional biogeochemical cycles of carbon (C) and nitrogen (N) in addition to regional radiation budgets. Owing to multiplicity of primary sources of natural and anthropogenic origin, their detailed chemical and isotopic characterization can greatly help in source apportionment and identifying secondary processes. From the roof of NIO-Goa (India) [15.46οN, 73.8oE; at ~55.8 MASL], atmospheric bulk aerosols (n=22) were collected on Quartz filters, from 2009 December to January 2011 covering entire 2010 (except monsoon period) to investigate temporal variability in their chemical and isotopic characteristics of the carbonaceous fraction i.e. TC, TOC and TN mass concentrations and their stable isotopic ratios (δ13CTC, δ13CTOC and δ15NTN). Both δ13CTC and δ13CTOC varied in narrow ranges (-24.9±1.1‰, -25.7±0.9‰ respectively), but significant differences were observed between the two during pre-monsoon months (as high as 2.3‰), possibly due to mixing of inorganic mineral dust. δ15NTN values showed a wide range of variability (average = 13.6±7.2‰), with significantly lower values (~2-5‰; as reported earlier by Agnihotri et al. 2011) during pre-monsoon period compared to those during winter (as high as ~26‰). Using δ13CTC values and two end-member mixing model (assuming δ13C of marine and continental carbon as -21 and -27‰ respectively), the average marine carbon fraction for Goa aerosols was estimated as 36±18.5%, significantly higher than reported for Chennai aerosols (~19%) (Pavuluri et al., 2011), but close to the reported average for marine aerosols at Bermuda (38%) (Turekian et al., 2003). Chemical and isotopic characteristics of ambient aerosols over Goa along with contemporaneous meteorological data indicate that winter aerosols contain significant proportion of carbonaceous fraction originated from biomass burning and other anthropogenic activities carried out in northern parts of

  12. Does the ocean-atmosphere system have more than one stable mode of operation?

    NASA Technical Reports Server (NTRS)

    Broecker, W. S.; Peteet, D. M.; Rind, D.

    1985-01-01

    The climate record obtained from two long Greenland ice cores reveals several brief climate oscillations during glacial time. The most recent of these oscillations, also found in continental pollen records, has greatest impact in the area under the meteorological influence of the northern Atlantic, but none in the United States. This suggests that these oscillations are caused by fluctuations in the formation rate of deep water in the northern Atlantic. As the present production of deep water in this area is driven by an excess of evaporation over precipitation and continental runoff, atmospheric water transport may be an important element in climate change. Changes in the production rate of deep water in this sector of the ocean may push the climate system from one quasi-stable mode of operation to another.

  13. Fast and stable explicit operator splitting methods for phase-field models

    NASA Astrophysics Data System (ADS)

    Cheng, Yuanzhen; Kurganov, Alexander; Qu, Zhuolin; Tang, Tao

    2015-12-01

    Numerical simulations of phase-field models require long time computations and therefore it is necessary to develop efficient and highly accurate numerical methods. In this paper, we propose fast and stable explicit operator splitting methods for both one- and two-dimensional nonlinear diffusion equations for thin film epitaxy with slope selection and the Cahn-Hilliard equation. The equations are split into nonlinear and linear parts. The nonlinear part is solved using a method of lines together with an efficient large stability domain explicit ODE solver. The linear part is solved by a pseudo-spectral method, which is based on the exact solution and thus has no stability restriction on the time-step size. We demonstrate the performance of the proposed methods on a number of one- and two-dimensional numerical examples, where different stages of coarsening such as the initial preparation, alternating rapid structural transition and slow motion can be clearly observed.

  14. Stable operation of a Secure QKD system in the real-world setting

    NASA Astrophysics Data System (ADS)

    Tomita, Akihisa

    2007-06-01

    Quantum Key Distribution (QKD) now steps forward from the proof of principle to the validation of the practical feasibility. Nevertheless, the QKD technology should respond to the challenges from the real-world such as stable operation against the fluctuating environment, and security proof under the practical setting. We report our recent progress on stable operation of a QKD system, and key generation with security assurance. A QKD system should robust to temperature fluctuation in a common office environment. We developed a loop-mirror, a substitution of a Faraday mirror, to allow easy compensation for the temperature dependence of the device. Phase locking technique was also employed to synchronize the system clock to the quantum signals. This technique is indispensable for the transmission system based on the installed fiber cables, which stretch and shrink due to the temperature change. The security proof of QKD, however, has assumed the ideal conditions, such as the use of a genuine single photon source and/or unlimited computational resources. It has been highly desirable to give an assurance of security for practical systems, where the ideal conditions are no longer satisfied. We have constructed a theory to estimate the leakage information on the transmitted key under the practically attainable conditions, and have developed a QKD system equipped with software for secure key distillation. The QKD system generates the final key at the rate of 2000 bps after 20 km fiber transmission. Eavesdropper's information on the final key is guaranteed to be less than 2-7 per bit. This is the first successful generation of the secure key with quantitative assurance of the upper bound of the leakage information. It will put forth the realization of highly secure metropolitan optical communication network against any types of eavesdropping.

  15. Stable operation of a slotted third-harmonic gyro-TWT amplifier

    SciTech Connect

    Chong, C.K.; McDermott, D.B.; Luhmann, N.C. Jr.

    1996-12-31

    A low magnetic field, moderate voltage gyrotron amplifier has been designed in collaboration with CPI/Varian for stable, high performance operation at 95 GHz and tested in a scaled experiment at 10 GHz. A slotted interaction circuit is utilized to achieve strong amplification at the third harmonic. The start-oscillation conditions were determined by an analytical theory that will be described. The dominant threat to the amplifier`s stability is from a third-harmonic peniotron backward-wave interaction. A self-consistent slow-timescale particle-tracing simulation code predicts the three-section, slotted third-harmonic gyro-TWT, which utilizes an 11.6 kG magnet and a 50 kV, 3 A, v{sub {perpendicular}}/v{sub Z} = 1.4, axis-encircling electron beam with an axial velocity spread of 6%, will yield an output power of 30 kW with an efficiency of 20%, a saturated gain of 40 dB and a constant-drive bandwidth of 2%.

  16. 50 mW stable single longitudinal mode operation of a 780 nm GaAlAs DFB laser

    SciTech Connect

    Takigawa, S.; Kume, M.; Hamada, K.; Yoshikawa, N.; Shimizu, H.; Gano, G.; Uno, T.

    1989-06-01

    Stable single longitudinal mode (SLM) operation has been attained with powers as high as 50 mW in a 780 nm GaAlAs distributed feedback laser. This excellent operation is due to the use of the buried twin-ridge substrate structure which allows the stable fundamental spatial mode operation even at high-power levels. The coupling strength designed is 0.5 from the viewpoint of obtaining a low operation current at 50 mW. The SLM operation in this laser was maintained for powers up to 50 mW at room temperature and in the temperature range from -17 to 37/sup 0/C at 50 mW. The maximum power attained was 62 mW.

  17. Delay Discounting Rates Are Temporally Stable in an Equivalent Present Value Procedure Using Theoretical and Area under the Curve Analyses

    ERIC Educational Resources Information Center

    Harrison, Justin; McKay, Ryan

    2012-01-01

    Temporal discounting rates have become a popular dependent variable in social science research. While choice procedures are commonly employed to measure discounting rates, equivalent present value (EPV) procedures may be more sensitive to experimental manipulation. However, their use has been impeded by the absence of test-retest reliability data.…

  18. A robust estimation model for surgery durations with temporal, operational, and surgery team effects.

    PubMed

    Kayış, Enis; Khaniyev, Taghi T; Suermondt, Jaap; Sylvester, Karl

    2015-09-01

    For effective operating room (OR) planning, surgery duration estimation is critical. Overestimation leads to underutilization of expensive hospital resources (e.g., OR time) whereas underestimation leads to overtime and high waiting times for the patients. In this paper, we consider a particular estimation method currently in use and using additional temporal, operational, and staff-related factors provide a statistical model to adjust these estimates for higher accuracy.The results show that our method increases the accuracy of the estimates, in particular by reducing large errors. For the 8093 cases we have in our data, our model decreases the mean absolute deviation of the currently used scheduled duration (42.65 ± 0.59 minutes) by 1.98 ± 0.28 minutes. For the cases with large negative errors, however, the decrease in the mean absolute deviation is 20.35 ± 0.74 minutes (with a respective increase of 0.89 ± 0.66 minutes in large positive errors). We find that not only operational and temporal factors, but also medical staff and team experience related factors (such as number of nurses and the frequency of the medical team working together) could be used to improve the currently used estimates. Finally, we conclude that one could further improve these predictions by combining our model with other good prediction models proposed in the literature. Specifically, one could decrease the mean absolute deviation of 39.98 ± 0.58 minutes obtained via the method of Dexter et al (Anesth Analg 117(1):204-209, 2013) by 1.02 ± 0.21 minutes by combining our method with theirs. PMID:25501470

  19. Ensemble Solute Transport in 2-D Operator-Stable Random Fields

    NASA Astrophysics Data System (ADS)

    Monnig, N. D.; Benson, D. A.

    2006-12-01

    The heterogeneous velocity field that exists at many scales in an aquifer will typically cause a dissolved solute plume to grow at a rate faster than Fick's Law predicts. Some statistical model must be adopted to account for the aquifer structure that engenders the velocity heterogeneity. A fractional Brownian motion (fBm) model has been shown to create the long-range correlation that can produce continually faster-than-Fickian plume growth. Previous fBm models have assumed isotropic scaling (defined here by a scalar Hurst coefficient). Motivated by field measurements of aquifer hydraulic conductivity, recent techniques were developed to construct random fields with anisotropic scaling with a self-similarity parameter that is defined by a matrix. The growth of ensemble plumes is analyzed for transport through 2-D "operator- stable" fBm hydraulic conductivity (K) fields. Both the longitudinal and transverse Hurst coefficients are important to both plume growth rates and the timing and duration of breakthrough. Smaller Hurst coefficients in the transverse direction lead to more "continuity" or stratification in the direction of transport. The result is continually faster-than-Fickian growth rates, highly non-Gaussian ensemble plumes, and a longer tail early in the breakthrough curve. Contrary to some analytic stochastic theories for monofractal K fields, the plume growth rate never exceeds Mercado's [1967] purely stratified aquifer growth rate of plume apparent dispersivity proportional to mean distance. Apparent super-Mercado growth must be the result of other factors, such as larger plumes corresponding to either a larger initial plume size or greater variance of the ln(K) field.

  20. Operative findings of conductive hearing loss with intact tympanic membrane and normal temporal bone computed tomography.

    PubMed

    Kim, Se-Hyung; Cho, Yang-Sun; Kim, Hye Jeong; Kim, Hyung-Jin

    2014-06-01

    Despite recent technological advances in diagnostic methods including imaging technology, it is often difficult to establish a preoperative diagnosis of conductive hearing loss (CHL) in patients with an intact tympanic membrane (TM). Especially, in patients with a normal temporal bone computed tomography (TBCT), preoperative diagnosis is more difficult. We investigated middle ear disorders encountered in patients with CHL involving an intact TM and normal TBCT. We also analyzed the surgical results with special reference to the pathology. We reviewed the medical records of 365 patients with intact TM, who underwent exploratory tympanotomy for CHL. Fifty nine patients (67 ears, eight bilateral surgeries) had a normal preoperative TBCT findings reported by neuro-radiologists. Demographic data, otologic history, TM findings, preoperative imaging findings, intraoperative findings, and pre- and postoperative audiologic data were obtained and analyzed. Exploration was performed most frequently in the second and fifth decades. The most common postoperative diagnosis was stapedial fixation with non-progressive hearing loss. The most commonly performed hearing-restoring procedure was stapedotomy with piston wire prosthesis insertion. Various types of hearing-restoring procedures during exploration resulted in effective hearing improvement, especially with better outcome in the ossicular chain fixation group. In patients with CHL who have intact TM and normal TBCT, we should consider an exploratory tympanotomy for exact diagnosis and hearing improvement. Information of the common operative findings from this study may help in preoperative counseling. PMID:23744181

  1. Operation of a stable 200-kW second-harmonic gyro-TWT amplifier

    SciTech Connect

    Wang, Q.S.; McDermott, D.B.; Luhmann, N.C. Jr.

    1996-06-01

    The experimental results are reported for a stable second-harmonic gyrotron traveling wave amplifier, which generated a record-breaking 207-kW output power based on the principle that the weaker harmonic interactions are more stable to spontaneous oscillations than at the fundamental, and therefore, capable of generating higher output power. The high-power amplifier was kept completely (zero-drive) stable by employing a mode-selective interaction circuit and well-matched directional input and output couplers, and choosing an amplifier interaction length shorter than the start-oscillation length for gyrotron backward-wave oscillations. The single-stage Ku-band amplifier utilized an 80-kV 20-A {upsilon}{sub {perpendicular}}/{upsilon}{sub {parallel}} = 1.1 electron beam from a magnetron injection gun and yielded an efficiency of 12.9%, an output phase variation of 10{degree}/kV, a saturated bandwidth of 2.1%, a large-signal gain of 16 dB, and a detuned small-signal gain of 38 dB.

  2. Spatial and temporal variability of compound-specific stable isotope (CSSI) biomarkers in soil and sediment tracing: towards improved sampling protocols

    NASA Astrophysics Data System (ADS)

    Reiffarth, Dominic; Petticrew, Ellen; Owens, Philip; Lobb, David

    2016-04-01

    The use of CSSI in biomarkers, specifically fatty acids and derivatives thereof, has recently been investigated as a potential tracer in soil and sediment fingerprinting. The use of CSSIs is of interest because of the potential to discern sediment providence based on land use, which is often difficult or not possible with other tracing techniques alone, such as geochemistry and fallout radionuclides. However, challenges exist in producing a representative sample of potential source materials. This presentation focuses on the development of improved protocols for sample collection. The data presented here are part of a larger investigation into using CSSIs as tracers in an agricultural watershed (South Tobacco Creek) in southern Manitoba, Canada. Extensive sampling was performed throughout the 2012 and 2013 growing seasons in several locations within the watershed, with a focus on capturing within and between field spatial and temporal variability in one particular sub-watershed (the "Stepler" watershed). The Stepler watershed provided a unique opportunity to perform sampling in a natural environment where agricultural crops were hydrologically separated, thereby allowing for a sampling regime of transects strategically placed with little influence from nearby crops. A portion of the data which has been analyzed, showing temporal and spatial variability in terms of carbon stable isotope signal, biomarker concentrations and soil organic carbon, is presented. As CSSI protocols for tracing are still in development, these data aid in determining the robustness of the technique as well as helping to inform sampling approaches.

  3. Intersensory selective attention and temporal orienting operate in parallel and are instantiated in spatially distinct sensory and motor cortices.

    PubMed

    Pomper, Ulrich; Keil, Julian; Foxe, John J; Senkowski, Daniel

    2015-08-01

    Knowledge about the sensory modality in which a forthcoming event might occur permits anticipatory intersensory attention. Information as to when exactly an event occurs enables temporal orienting. Intersensory and temporal attention mechanisms are often deployed simultaneously, but as yet it is unknown whether these processes operate interactively or in parallel. In this human electroencephalography study, we manipulated intersensory attention and temporal orienting in the same paradigm. A continuous stream of bisensory visuo-tactile inputs was presented, and a preceding auditory cue indicated to which modality participants should attend (visual or tactile). Temporal orienting was manipulated blockwise by presenting stimuli either at regular or irregular intervals. Using linear beamforming, we examined neural oscillations at virtual channels in sensory and motor cortices. Both attentional processes simultaneously modulated the power of anticipatory delta- and beta-band oscillations, as well as delta-band phase coherence. Modulations in sensory cortices reflected intersensory attention, indicative of modality-specific gating mechanisms. Modulations in motor and partly in somatosensory cortex reflected temporal orienting, indicative of a supramodal preparatory mechanism. We found no evidence for interactions between intersensory attention and temporal orienting, suggesting that these two mechanisms act in parallel and largely independent of each other in sensory and motor cortices. PMID:26032901

  4. Elastomeric Microchip Electrospray Emitter for Stable Cone-Jet Mode Operation in the Nanoflow Regime.

    SciTech Connect

    Kelly, Ryan T.; Tang, Keqi; Irimia, Daniel; Toner, Mehmet; Smith, Richard D.

    2008-05-15

    Despite widespread interest in applying lab-on-a-chip technologies to mass spectrometry (MS)-based analyses, the coupling of microfluidics to electrospray ionization (ESI)-MS remains challenging. We report a robust, integrated poly(dimethylsiloxane) microchip interface for ESI-MS using simple and widely accessible microfabrication procedures. The interface uses an auxiliary channel to provide electrical contact in the Taylor cone of the electrospray without sample loss or dilution. The electric field at the channel terminus is enhanced by two vertical cuts that cause the interface to taper to a line rather than to a point, and the formation of small Taylor cones at the channel exit ensures sub-nL post-column dead volumes. While comparable ESI-MS sensitivities were achieved using both microchip and conventional fused silica capillary emitters, stable cone-jet mode electrospray could be established over a far broader range of flow rates (from 50–1000 nL/min) and applied potentials using the microchip emitters. This special feature of the microchip emitter should minimize the fine tuning required for electrospray optimization and make the stable electrospray more resistant to external perturbations.

  5. Devices and methods of operation thereof for providing stable flow for centrifugal compressors

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J. (Inventor); Stevens, Mark A. (Inventor); Jett, Thomas A. (Inventor)

    2008-01-01

    Centrifugal compressor flow stabilizing devices and methods of operation thereof are disclosed that act upon the flow field discharging from the impeller of a centrifugal compressor and modify the flow field ahead of the diffuser vanes such that flow conditions contributing to rotating stall and surge are reduced or even eliminated. In some embodiments, shaped rods and methods of operation thereof are disclosed, whereas in other embodiments reverse-tangent air injection devices and methods are disclosed.

  6. Temporal changes in methane stable isotopes in polar ice cores: big picture and implications for ecosystem changes

    NASA Astrophysics Data System (ADS)

    Bock, Michael; Schmitt, Jochen; Seth, Barbara; Beck, Jonas; Fischer, Hubertus

    2014-05-01

    Methane (CH4) is the third most important greenhouse gas after water vapour and carbon dioxide (CO2). Since the industrial revolution the mixing ratio of CH4 in the atmosphere rose to ~1800 ppb, a value never reached within the last 800 000 years. Nowadays, CH4 contributes ~20% to the total radiative forcing from all of the long-lived greenhouse gases. This CH4 increase can only be assessed in relation to natural methane changes in the past. Firn air and air enclosures in polar ice cores represent the only direct paleoatmospheric archive. The latter show that atmospheric CH4 concentrations changed in concert with northern hemisphere temperature during both glacial/interglacial transitions as well as rapid climate changes (Dansgaard-Oeschger events), however, the sources of the methane concentration changes are still a matter of debate. Stable isotopes of methane (δ13CH4 and δD(CH4)) may help to distinguish differences in the magnitude of source type emissions (e.g. Bock et al. 2010). However, recently we could show that it is difficult to interpret the atmospheric loading of methane by relative source mix changes alone (Möller et al. 2013). In fact it appears, that the carbon isotopic signature (δ13CH4) of e.g. tropical wetlands undergoes drastic shifts connected to climate, CO2, sea level or potentially other unknown processes. Here we present the big picture derived from the EDML (European Project for Ice Coring in Antarctica, Dronning Maud Land) and Vostok ice cores (Möller et al. 2013) and additional new dual isotope data from 4 ice cores from both poles that cover three interglacials: the Holocene, MIS 5 and MIS 11. The contribution sheds light on our current understanding of methane biogeochemistry and discusses open questions. References: Bock, M., J. Schmitt, L. Möller, R. Spahni, T. Blunier, H. Fischer (2010). 'Hydrogen Isotopes Preclude Marine Hydrate CH4 Emissions at the Onset of Dansgaard-Oeschger Events', Science, 328, 1686-1689 Möller, L., T

  7. Graph theoretical stable allocation as a tool for reproduction of control by human operators

    NASA Astrophysics Data System (ADS)

    van Nooijen, Ronald; Ertsen, Maurits; Kolechkina, Alla

    2016-04-01

    During the design of central control algorithms for existing water resource systems under manual control it is important to consider the interaction with parts of the system that remain under manual control and to compare the proposed new system with the existing manual methods. In graph theory the "stable allocation" problem has good solution algorithms and allows for formulation of flow distribution problems in terms of priorities. As a test case for the use of this approach we used the algorithm to derive water allocation rules for the Gezira Scheme, an irrigation system located between the Blue and White Niles south of Khartoum. In 1925, Gezira started with 300,000 acres; currently it covers close to two million acres.

  8. [Startup, stable operation and process failure of EBPR system under the low temperature and low dissolved oxygen condition].

    PubMed

    Ma, Juan; Li, Lu; Yu, Xiao-Jun; Wei, Xue-Fen; Liu, Juan-Li

    2015-02-01

    A sequencing batch reactor (SBR) was started up and operated with alternating anaerobic/oxic (An/O) to perform enhanced biological phosphorus removal (EBPR) under the condition of 13-16 degrees C. The results showed that under the condition of low temperature, the EBPR system was successfully started up in a short time (<6 d). The reactor achieved a high and stable phosphorus removal performance with an influent phosphate concentration of 20 mg x L(-1) and the dissolved oxygen (DO) concentration of 2 mg x L(-1). The effluent phosphate concentration was lower than 0.5 mg x L(-1). It was found that decreasing DO had an influence on the steady operation of EBPR system. As DO concentration of aerobic phase decreased from 2 mg x L(-1) to 1 mg x L(-1), the system could still perform EBPR and the phosphorus removal efficiency was greater than 97.4%. However, the amount of phosphate released during anaerobic phase was observed to decrease slightly compared with that of 2 mg x L(-1) DO condition. Moreover, the phosphorus removal performance of the system deteriorated immediately and the effluent phosphate concentration couldn't meet the national integrated wastewater discharge standard when DO concentration was further lowered to 0.5 mg x L(-1). The experiments of increasing DO to recover phosphorus removal performance of the EBPR suggested the process failure resulted from low DO was not reversible in the short-term. It was also found that the batch tests of anoxic phosphorus uptake using nitrite and nitrate as electron acceptors had an impact on the stable operation of EBPR system, whereas the resulting negative influence could be recovered within 6 cycles. In addition, the mixed liquid suspended solids (MLSS) of the EBPR system remained stable and the sludge volume index (SVI) decreased to a certain extend in a long run, implying long-term low temperature and low DO condition favored the sludge sedimentation. PMID:26031088

  9. Adaptive Technologies Developed and Demonstrated for Extending the Stable Operating Range of Compressors

    NASA Technical Reports Server (NTRS)

    Hathaway, Michael D.; Strazisar, Anthony J.

    2005-01-01

    The operational envelope of gas turbine engines is constrained by the stability limit of the compression system. The dangers of exceeding this limit are severe, with the potential for engine failure and loss of the aircraft. To avoid such failures, compressor designers provide an adequate stability (stall) margin in the compressor design to account for inlet distortions, degradation due to wear, throttle transients, and other factors that reduce compressor stability from the original design intent. In some cases, the required stall margin results in the compressor operating line being below the maximum efficiency potential of the compression system. Current approaches to increasing stability tend to decrease the efficiency of the compressor. The focus of this work is to increase the stall margin of compressors without decreasing their efficiency.

  10. Design optimization of MR-compatible rotating anode x-ray tubes for stable operation

    SciTech Connect

    Shin, Mihye; Lillaney, Prasheel; Hinshaw, Waldo; Fahrig, Rebecca

    2013-11-15

    Purpose: Hybrid x-ray/MR systems can enhance the diagnosis and treatment of endovascular, cardiac, and neurologic disorders by using the complementary advantages of both modalities for image guidance during interventional procedures. Conventional rotating anode x-ray tubes fail near an MR imaging system, since MR fringe fields create eddy currents in the metal rotor which cause a reduction in the rotation speed of the x-ray tube motor. A new x-ray tube motor prototype has been designed and built to be operated close to a magnet. To ensure the stability and safety of the motor operation, dynamic characteristics must be analyzed to identify possible modes of mechanical failure. In this study a 3D finite element method (FEM) model was developed in order to explore possible modifications, and to optimize the motor design. The FEM provides a valuable tool that permits testing and evaluation using numerical simulation instead of building multiple prototypes.Methods: Two experimental approaches were used to measure resonance characteristics: the first obtained the angular speed curves of the x-ray tube motor employing an angle encoder; the second measured the power spectrum using a spectrum analyzer, in which the large amplitude of peaks indicates large vibrations. An estimate of the bearing stiffness is required to generate an accurate FEM model of motor operation. This stiffness depends on both the bearing geometry and adjacent structures (e.g., the number of balls, clearances, preload, etc.) in an assembly, and is therefore unknown. This parameter was set by matching the FEM results to measurements carried out with the anode attached to the motor, and verified by comparing FEM predictions and measurements with the anode removed. The validated FEM model was then used to sweep through design parameters [bearing stiffness (1×10{sup 5}–5×10{sup 7} N/m), shaft diameter (0.372–0.625 in.), rotor diameter (2.4–2.9 in.), and total length of motor (5.66–7.36 in.)] to

  11. Design optimization of MR-compatible rotating anode x-ray tubes for stable operation

    PubMed Central

    Shin, Mihye; Lillaney, Prasheel; Hinshaw, Waldo; Fahrig, Rebecca

    2013-01-01

    Purpose: Hybrid x-ray/MR systems can enhance the diagnosis and treatment of endovascular, cardiac, and neurologic disorders by using the complementary advantages of both modalities for image guidance during interventional procedures. Conventional rotating anode x-ray tubes fail near an MR imaging system, since MR fringe fields create eddy currents in the metal rotor which cause a reduction in the rotation speed of the x-ray tube motor. A new x-ray tube motor prototype has been designed and built to be operated close to a magnet. To ensure the stability and safety of the motor operation, dynamic characteristics must be analyzed to identify possible modes of mechanical failure. In this study a 3D finite element method (FEM) model was developed in order to explore possible modifications, and to optimize the motor design. The FEM provides a valuable tool that permits testing and evaluation using numerical simulation instead of building multiple prototypes. Methods: Two experimental approaches were used to measure resonance characteristics: the first obtained the angular speed curves of the x-ray tube motor employing an angle encoder; the second measured the power spectrum using a spectrum analyzer, in which the large amplitude of peaks indicates large vibrations. An estimate of the bearing stiffness is required to generate an accurate FEM model of motor operation. This stiffness depends on both the bearing geometry and adjacent structures (e.g., the number of balls, clearances, preload, etc.) in an assembly, and is therefore unknown. This parameter was set by matching the FEM results to measurements carried out with the anode attached to the motor, and verified by comparing FEM predictions and measurements with the anode removed. The validated FEM model was then used to sweep through design parameters [bearing stiffness (1×105–5×107 N/m), shaft diameter (0.372–0.625 in.), rotor diameter (2.4–2.9 in.), and total length of motor (5.66–7.36 in.)] to increase the

  12. In-situ measurements of pore water stable isotope composition in a semi-arid environment with implications for spatio-temporal variability of unsaturated zone processes.

    NASA Astrophysics Data System (ADS)

    Gaj, Marcel; Beyer, Matthias; Koeniger, Paul; Hamutoko, Yosefina; Himmelsbach, Thomas

    2015-04-01

    Northern Namibia is a region with high population growth, limited water resources and a transboundary aquifer system where groundwater recharge and groundwater flow processes are not yet well understood. Our study is an interdisciplinary approach to improve the understanding of links between hydrological, geochemical and ecological processes to estimate areas that contribute to recharge a shallow aquifer system. To determine the spatial variability of infiltration and evapotranspiration processes within the critical interface and between the atmosphere and the groundwater nine plots in an area of 9,000 m2 were investigated. Stable isotopes (deuterium, δ2H, and oxygen-18, δ18O) of soil pore water were measured directly in the field using a LGR-DLT100 and commercially available soil gas probes (BGL-30, UMS). Additionally, soil moisture and temperature were recorded. After drift correction of the isotope data the long term precision using a quality check standard for 221 measurement points of a two week period was between 6.3 - 7.4 o for δ2H and 1.3 - 3.6 o for δ18O. Each point was measured with six repetitions were the mean standard deviation for all quality check standards was 1.3 - 1.6 o for δ2H and 0.23 - 0.30 o for δ18O. It could be observed that the quality of the measurements decreased with increasing number of measurements due to a memory effect of the probes enhanced by organic contamination of the membrane pores. However, results support the applicability of an in-situ system for the determination of stable isotopes in soil pore water. Spatially and temporal variability affected by intermitted light rainfall events can be deduced with the observed data.

  13. Frequency characteristics of an inherently stable Nd:YAG laser operated at liquid helium temperature

    SciTech Connect

    Scholz, Matthias; Kovalchuk, Evgeny; Peters, Achim

    2009-07-10

    We report on frequency measurements of a free-running Nd:YAG laser operating at temperatures down to 6.5 K using a femtosecond laser frequency comb. Due to lower thermal expansion and thermo-optic effects as well as reduced electron-phonon interactions in Nd:YAG at cryogenic temperatures, a laser frequency stability on the order of 10{sup -11} at {tau} < or = 30s has been achieved. Within a one-week measurement period, absolute frequency deviations were lower than 1.85 MHz. This is up to a 100-fold improvement of frequency stability compared to any existing free-running solid-state laser.

  14. Stable Electrical Operation of 6H-SiC JFETs and ICs for Thousands of Hours at 500 C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Spry, David J.; Chen, Liang-Yu; Beheim, Glenn M.; Okojie, Robert S.; Chang, Carl W.; Meredith, Roger D.; Ferrier, Terry L.; Evans, Laura J.; Krasowski, Michael J.; Prokop, Norman F.

    2008-01-01

    The fabrication and testing of the first semiconductor transistors and small-scale integrated circuits (ICs) to achieve up to 3000 h of stable electrical operation at 500 C in air ambient is reported. These devices are based on an epitaxial 6H-SiC junction field-effect transistor process that successfully integrated high temperature ohmic contacts, dielectric passivation, and ceramic packaging. Important device and circuit parameters exhibited less than 10% of change over the course of the 500 C operational testing. These results establish a new technology foundation for realizing durable 500 C ICs for combustion-engine sensing and control, deep-well drilling, and other harsh-environment applications.

  15. Nonlinear dynamics analysis of a membrane Stirling engine: Starting and stable operation

    NASA Astrophysics Data System (ADS)

    Formosa, Fabien

    2009-10-01

    This paper presents the work devoted to the study of the operation of a miniaturized membrane Stirling engine. Indeed, such an engine relies on the dynamic coupling of the motion of two membranes to achieve a prime mover Stirling thermodynamic cycle. The modelling of the system introduces the large vibration amplitudes of the membrane as well as the nonlinear dissipative effects associated to the fluid flow within the engine. The nonlinearities are expressed as polynomial functions with quadratic and cubic terms. This paper displays the stability analysis to predict the starting of the engine and the instability problem which leads to the steady-state behaviour. The centre manifold-normal form theory is used to obtain the simplest expression for the limit cycle amplitudes. The approach allows the reduction of the number of equations of the original system in order to obtain a simplified system, without loosing the dynamics of the original system as well as the contributions of nonlinear terms. The model intends to be used as a semi-analytical design tool for the optimization of miniaturized Stirling machines from the starting to the steady operation.

  16. Stable single-mode operation of surface-emitting terahertz lasers with graded photonic heterostructure resonators

    NASA Astrophysics Data System (ADS)

    Xu, Gangyi; Halioua, Yacine; Moumdji, Souad; Colombelli, Raffaele; Beere, Harvey E.; Ritchie, David A.

    2013-06-01

    Graded photonic heterostructures (GPH) can be regarded as energy wells for photons. We show that judicious engineering of such photonic wells, obtained by tailoring the grading and the slit width of the GPH resonator, allows one to ensure spectrally single-mode emission on the fundamental symmetric mode in the whole lasing dynamical range of terahertz quantum cascade lasers. Furthermore, the radiative character of the symmetric mode leads to single-mode emission with mW output power in continuous-wave operation, as well as to single-lobed far-field beam patterns. A careful combination of theoretical analysis and experimental observations reveals that the results stem from interplay between mode competition and spatial hole burning effects.

  17. Development of a muon radiographic imaging electronic board system for a stable solar power operation

    NASA Astrophysics Data System (ADS)

    Uchida, T.; Tanaka, H. K. M.; Tanaka, M.

    2010-02-01

    Cosmic-ray muon radiography is a method that is used to study the internal structure of volcanoes. We have developed a muon radiographic imaging board with a power consumption low enough to be powered by a small solar power system. The imaging board generates an angular distribution of the muons. Used for real-time reading, the method may facilitate the prediction of eruptions. For real-time observations, the Ethernet is employed, and the board works as a web server for a remote operation. The angular distribution can be obtained from a remote PC via a network using a standard web browser. We have collected and analyzed data obtained from a 3-day field study of cosmic-ray muons at a Satsuma-Iwojima volcano. The data provided a clear image of the mountain ridge as a cosmic-ray muon shadow. The measured performance of the system is sufficient for a stand-alone cosmic-ray muon radiography experiment.

  18. Functionalizing Titanium Disilicide Nanonets with Cobalt Oxide and Palladium for Stable Li Oxygen Battery Operations.

    PubMed

    Yao, Xiahui; Cheng, Qingmei; Xie, Jin; Dong, Qi; Wang, Dunwei

    2015-10-01

    Li oxygen (Li-O2) batteries promise high energy densities but suffer from challenges such as poor cycling lifetime and low round-trip efficiencies. Recently, the instability of carbon cathode support has been recognized to contribute significantly to the problems faced by Li-O2 batteries. One strategy to address the challenge is to replace carbon materials with carbon-free ones. Here, we present titanium silicide nanonets (TiSi2) as such a new material platform for this purpose. Because TiSi2 exhibits no oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) activities, catalysts are required to promote discharge and recharge reactions at reduced overpotentials. Pd nanoparticles grown by atomic layer deposition (ALD) were observed to provide the bifunctionalities of ORR and OER. Their adhesion to TiSi2 nanonets, however, was found to be poor, leading to drastic performance decay due to Pd detachments and aggregation. The problem was solved by adding another layer of Co3O4, also prepared by ALD. Together, the Pd/Co3O4/TiSi2 combination affords the desired functionalities and stability. Li-O2 test cells that lasted more than 126 cycles were achieved. The reversible formation and decomposition of Li2O2 was verified by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), ferrocenium back-titration, and gas-chromatography and mass spectrometry (GC-MS). Our results provide a new material platform for detailed studies of Li-O2 operations for better understanding of the chemistries involved, which is expected to help pave the way toward practical Li-O2 battery realizations. PMID:26308102

  19. Development of operationally stable inverted organic light-emitting diode prepared without using alkali metals (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Fukagawa, Hirohiko; Morii, Katsuyuki; Hasegawa, Munehiro; Gouda, Shun; Tsuzuki, Toshimitsu; Shimizu, Takahisa; Yamamoto, Toshihiro

    2015-10-01

    The OLED is one of the key devices for realizing future flexible displays and lightings. One of the biggest challenges left for the OLED fabricated on a flexible substrate is the improvement of its resistance to oxygen and moisture. A high barrier layer [a water vapor transmission rate (WVTR) of about 10-6 g/m2/day] is proposed to be necessary for the encapsulation of conventional OLEDs. Some flexible high barrier layers have recently been demonstrated; however, such high barrier layers require a complex process, which makes flexible OLEDs expensive. If an OLED is prepared without using air-sensitive materials such as alkali metals, no stringent encapsulation is necessary for such an OLED. In this presentation, we will discuss our continuing efforts to develop an inverted OLED (iOLED) prepared without using alkali metals. iOLEDs with a bottom cathode are considered to be effective for realizing air-stable OLEDs since the electron injection layer (EIL) can be prepared by fabrication processes that might damage the organic layers, resulting in the enhanced range of materials suitable for EILs. We have demonstrated that a highly efficient and relatively air-stable iOLED can be realized by employing poly(ethyleneimine) as an EIL. Dark spot formation was not observed after 250 days in the poly(ethyleneimine)-based iOLED encapsulated by a barrier film with a WVTR of 10-4 g/m2/day. In addition, we have demonstrated the fabrication of a highly operational stable iOLED utilizing a newly developed EIL. The iOLED exhibits an expected half-lifetime of over 10,000 h from an initial luminance of 1,000 cd/m2.

  20. Peritoneal Breach as an Indication for Exploratory Laparotomy in Penetrating Abdominal Stab Injury: Operative Findings in Haemodynamically Stable Patients

    PubMed Central

    Aguirre, Victor; Martin, Kate; Varma, Dinesh; Fitzgerald, Mark; Pilgrim, Charles

    2015-01-01

    Introduction. Management of haemodynamically stable patients with penetrating abdominal injuries varies from nonoperative to operative management. The aim was to investigate whether peritoneal breach when used as an indication for exploratory laparotomy appropriately identified patients with intra-abdominal visceral injury. Methods. We conducted retrospective cohort study of all patients presenting with PAI at a major trauma centre from January 2007 to December 2011. We measured the incidence of peritoneal breach and correlated this with intra-abdominal visceral injury diagnosed at surgery. Results. 252 patients were identified with PAI. Of the included patients, 71 were managed nonoperatively and 118 operatively. The operative diagnoses included nonperitoneal-breaching injuries, intraperitoneal penetration without organ damage, or intraperitoneal injury with organ damage. The presenting trauma CT scan was reported as normal in 63%, 34%, and 2% of these groups, respectively. The total negative laparotomy/laparoscopy rate for all patients presented with PAI was 21%, almost half of whom had a normal CT scan. Conclusion. We found that peritoneal breach on its own does not necessarily always equate to intra-abdominal visceral injury. Observation with sequential examination for PAI patients with a normal CT scan may be more important than exclusion of peritoneal breach via laparoscopy. PMID:26064688

  1. Prospects for Ultra-Stable Timekeeping with Sealed Vacuum Operation in Multi-Pole Linear Ion Trap Standards

    NASA Technical Reports Server (NTRS)

    Burt, Eric A.; Tjoelker, R. L.

    2007-01-01

    A recent long-term comparison between the compensated multi-pole Linear Ion Trap Standard (LITS) and the laser-cooled primary standards via GPS carrier phase time transfer showed a deviation of less than 2.7x10(exp -17)/day. A subsequent evaluation of potential drift contributors in the LITS showed that the leading candidates are fluctuations in background gases and the neon buffer gas. The current vacuum system employs a "flow-through" turbomolecular pump and a diaphragm fore pump. Here we consider the viability of a "sealed" vacuum system pumped by a non-evaporable getter for long-term ultra-stable clock operation. Initial tests suggests that both further stability improvement and longer mean-time-between-maintenance can be achieved using this approach

  2. Operating conditions for the generation of stable anode spot plasma in front of a positively biased electrode.

    PubMed

    Park, Yeong-Shin; Lee, Yuna; Dang, Jeong-Jeung; Chung, Kyoung-Jae; Hwang, Y S

    2014-02-01

    Stability of an anode spot plasma, which is an additional high density plasma generated in front of a positively biased electrode immersed in ambient plasma, is a critical issue for its utilization to various types of ion sources. In this study, operating conditions for the generation of stable anode spot plasmas are experimentally investigated. Diagnostics of the bias current flowing into the positively biased electrode and the properties of ambient plasma reveal that unstable nature of the anode spot is deeply associated with the reduction of double layer potential between the anode spot plasma and the ambient plasma. It is found that stability of the anode spot plasma can be improved with increasing the ionization rate in ambient plasma so as to compensate the loss of electrons across the double layer or with enlarging the area of the biased electrode to prevent electron accumulation inside the anode spot. The results obtained from the present study give the guideline for operating conditions of anode spot plasmas as an ion source with high brightness. PMID:24593431

  3. Water column distribution of stable isotopes and carbonate properties in the South-eastern Levantine basin (Eastern Mediterranean): Vertical and temporal change

    NASA Astrophysics Data System (ADS)

    Sisma-Ventura, G.; Yam, R.; Kress, N.; Shemesh, A.

    2016-06-01

    Water column distributions of the oxygen isotopic composition of sea-water (δ18OSW) and the stable carbon isotope ratio of dissolved inorganic carbon (δ13CDIC), total alkalinity (AT) and the pH (total scale) at 25 °C (25 °CpHTotal) were investigated along the Southeast Mediterranean (SE-Med) shelf and open water, during 2009-2010. While, the vertical profiles of δ18OSW lacked a clear depth signature, those of δ13CDIC were characterized by a structure that reflects the major water masses in the Levantine basin, with noticeable vertical gradients. The δ13CDIC Suess effect of the Levantine water column was estimated from the difference between the average profiles of 1988 and 2009-2010 (Δδ13CDIC). We observed δ13CDIC temporal change, which indicates propagation of anthropogenic CO2 (Cant) to depth of about 700 m. The Modified Atlantic Water (MAW; 0-200 m) and the Levantine Intermediate Water (LIW; 200-400 m) exhibited a depletion rate of - 0.13 ± 0.03 and - 0.11 ± 0.03‰ decade- 1, respectively, representing ~ 50% of the atmospheric change, while the deep water of the Adriatic source (700-1300 m) did not change during this period. A Δδ13CDIC depletion trend was also recognized below 1350 m, corresponding to the Aegean source deep water (EMDWAeg) and therefore associated to the Eastern Mediterranean Transient (EMT) event. Anthropogenic CO2 accumulation rate of 0.38 ± 0.12 mol C m- 2 yr- 1 for the upper 700 m of the SE-Med, over the last 22 yr, was estimated on the basis of mean depth-integrated δ13CDIC Suess effect profile. Our results confirm lower accumulation rate than that of the subtropical North Atlantic, resulting due to the super-saturation with respect to CO2 of the well-stratified Levantine surface water. High pCO2 saturation during summer (+ 150 μatm), in oppose to a small degree of under-saturation in winter (- 30 μatm) was calculated from surface water AT and 25 °CpHTotal data. However, the δ13CDIC depletion trend of the LIW and the

  4. Nonretinotopic perception of orientation: Temporal integration of basic features operates in object-based coordinates.

    PubMed

    Wutz, Andreas; Drewes, Jan; Melcher, David

    2016-08-01

    Early, feed-forward visual processing is organized in a retinotopic reference frame. In contrast, visual feature integration on longer time scales can involve object-based or spatiotopic coordinates. For example, in the Ternus-Pikler (T-P) apparent motion display, object identity is mapped across the object motion path. Here, we report evidence from three experiments supporting nonretinotopic feature integration even for the most paradigmatic example of retinotopically-defined features: orientation. We presented observers with a repeated series of T-P displays in which the perceived rotation of Gabor gratings indicates processing in either retinotopic or object-based coordinates. In Experiment 1, the frequency of perceived retinotopic rotations decreased exponentially for longer interstimulus intervals (ISIs) between T-P display frames, with object-based percepts dominating after about 150-250 ms. In a second experiment, we show that motion and rotation judgments depend on the perception of a moving object during the T-P display ISIs rather than only on temporal factors. In Experiment 3, we cued the observers' attentional state either toward a retinotopic or object motion-based reference frame and then tracked both the observers' eye position and the time course of the perceptual bias while viewing identical T-P display sequences. Overall, we report novel evidence for spatiotemporal integration of even basic visual features such as orientation in nonretinotopic coordinates, in order to support perceptual constancy across self- and object motion. PMID:27494545

  5. Temporally and functionally dissociable retrieval processing operations revealed by event-related potentials.

    PubMed

    Cruse, Damian; Wilding, Edward L

    2011-06-01

    In a pair of recent studies, frontally distributed event-related potential (ERP) indices of two distinct post-retrieval processes were identified. It has been proposed that one of these processes operates over any kinds of task relevant information in service of task demands, while the other operates selectively over recovered contextual (episodic) information. The experiment described here was designed to test this account, by requiring retrieval of different kinds of contextual information to that required in previous relevant studies. Participants heard words spoken in either a male or female voice at study and ERPs were acquired at test where all words were presented visually. Half of the test words had been spoken at study. Participants first made an old/new judgment, distinguishing via key press between studied and unstudied words. For words judged 'old', participants indicated the voice in which the word had been spoken at study, and their confidence (high/low) in the voice judgment. There was evidence for only one of the two frontal old/new effects that had been identified in the previous studies. One possibility is that the ERP effect in previous studies that was tied specifically to recollection reflects processes operating over only some kinds of contextual information. An alternative is that the index reflects processes that are engaged primarily when there are few contextual features that distinguish between studied stimuli. PMID:21382387

  6. How Stable Is Stable?

    ERIC Educational Resources Information Center

    Baehr, Marie

    1994-01-01

    Provides a problem where students are asked to find the point at which a soda can floating in some liquid changes its equilibrium between stable and unstable as the soda is removed from the can. Requires use of Newton's first law, center of mass, Archimedes' principle, stable and unstable equilibrium, and buoyant force position. (MVL)

  7. Gas-particle concentrations of atmospheric polycyclic aromatic hydrocarbons at an urban and a residential site in Osaka, Japan: effect of the formation of atmospherically stable layer on their temporal change.

    PubMed

    Kishida, Masao; Nishikawa, Ayako; Fujimori, Keiichi; Shibutani, Yasuhiko

    2011-09-15

    A comparative study on atmospheric polycyclic aromatic hydrocarbons (PAHs) in particulate matter and the gaseous phase was performed at an urban and a residential site in Osaka, Japan, during 2005-2006. PAH concentrations at the urban site were found to be approximately twice higher than those at the residential site. At both sites, particulate PAH concentrations increased mainly in winter while the trends of temporal change in gaseous PAH concentrations were not clearly observed. The main sources of PAHs were estimated to be local traffic, e.g., diesel engines with catalytic converter. PAH concentrations did not significantly negatively correlate with ozone concentrations and meteorological parameters. Gas-particle partitioning coefficients of representative PAHs with low molecular weight (LMW) significantly negatively correlated with ambient temperature, showing that temporal change in the LMW PAH concentrations in PM could be attributable to the shift of their gas-particle distribution caused by the change in ambient temperature. For the first time, we studied the effect of the formation of atmospherically stable layer following an increase in PAH concentrations in Japan. At the urban site, PAHs showed a significant positive correlation with potential temperature gradients, indicating that temporal variability in PAH concentrations would be dominantly controlled by the formation of atmospherically stable layer in Osaka area. PMID:21752537

  8. Correlated full-field and pointwise temporally resolved measurements of thermomechanical stress inside an operating power transistor

    NASA Astrophysics Data System (ADS)

    Borza, Dan N.; Gautrelet, Christophe

    2015-01-01

    The paper describes a measurement system based on time-resolved speckle interferometry, able to record long series of thermally induced full-field deformation maps of die and wire bonds inside an operating power transistor. The origin of the deformation is the transistor heating during its normal operation. The full-field results consist in completely unwrapped deformation maps for out-of-plane displacements greater than 14 μm, with nanometer resolution, in presence of discontinuities due to structural and material inhomogeneity. These measurements are synchronized with the measurement of heatsink temperature and of base-emitter junction temperature, so as to provide data related to several interacting physical parameters. The temporal histories of the displacement are also accessible for any point. They are correlated with the thermal and electrical time series. Mechanical full-field curvatures may also be estimated, making these measurements useful for inspecting physical origins of thermomechanical stresses and for interacting with numerical models used in reliability-related studies.

  9. The Nature of Temporally Variable Methane Emissions at Oil and Natural Gas Operations in the Eagle Ford Basin

    NASA Astrophysics Data System (ADS)

    Lavoie, T. N.; Shepson, P. B.; Cambaliza, M. O. L.; Stirm, B. H.; Conley, S. A.; Mehrotra, S.; Faloona, I. C.; Mayfield, M.; Lyon, D. R.; Alvarez, R.

    2015-12-01

    To understand the current state of U.S. greenhouse gas emissions from oil and gas operations, policy makers refer to national inventories and reporting programs, and therefore, it is imperative that these reports are accurate and representative. Many studies exist that investigate the reliability of current monitoring methods, however, to our knowledge the temporal variability of the magnitude and source of methane (CH4) emissions from oil and gas facilities has not been reported in the literature. We present results from a field campaign conducted in June 2014 in the Eagle Ford basin, Texas to assess the temporal variability of emissions from a variety of facilities using data obtained through four different methods. The variability of total CH4 emission rate from individual facilities was investigated by repeated measurement of emissions from five gathering facilities using two aircraft-based mass balance approaches. Basin-wide emissions variation was examined by conducting a series of eight four hour afternoon aerial surveys of two 35 x 35 km areas, with transects oriented perpendicular to the prevailing wind direction. The emission source-type and magnitude were further investigated using helicopter-based FLIR camera observations conducted repeatedly at eight oil wells, one gas well, and four gathering facilities. Results indicate a high degree of variability in day-to-day and sometimes hour-to-hour CH4 emissions magnitude. FLIR camera observations suggest that the component-level source of facility emissions is also highly variable over time, with both storage tank vent stacks and tank hatches representing important components of the observed day-to-day variability. While some emissions were due to scheduled maintenance, others appeared to occur due to faulty and/or aging equipment. Here we discuss what was learned in terms of factors that explain the observed emission rate variability.

  10. Spatial and temporal variations in indoor environmental conditions, human occupancy, and operational characteristics in a new hospital building

    SciTech Connect

    Ramos, Tiffanie; Dedesko, Sandra; Siegel, Jeffrey A.; Gilbert, Jack A.; Stephens, Brent

    2015-03-02

    The dynamics of indoor environmental conditions, human occupancy, and operational characteristics of buildings influence human comfort and indoor environmental quality, including the survival and progression of microbial communities. A suite of continuous, long-term environmental and operational parameters were measured in ten patient rooms and two nurse stations in a new hospital building in Chicago, IL to characterize the indoor environment in which microbial samples were taken for the Hospital Microbiome Project. Measurements included environmental conditions (indoor dry-bulb temperature, relative humidity, humidity ratio, and illuminance) in the patient rooms and nurse stations; differential pressure between the patient rooms and hallways; surrogate measures for human occupancy and activity in the patient rooms using both indoor air CO₂ concentrations and infrared doorway beam-break counters; and outdoor air fractions in the heating, ventilating, and air-conditioning systems serving the sampled spaces. Measurements were made at 5-minute intervals over consecutive days for nearly one year, providing a total of ~8×10⁶ data points. Indoor temperature, illuminance, and human occupancy/activity were all weakly correlated between rooms, while relative humidity, humidity ratio, and outdoor air fractions showed strong temporal (seasonal) patterns and strong spatial correlations between rooms. Differential pressure measurements confirmed that all patient rooms were operated at neutral pressure. The patient rooms averaged about 100 combined entrances and exits per day, which suggests they were relatively lightly occupied compared to higher traffic environments (e.g., retail buildings) and more similar to lower traffic office environments. There were also clear differences in several environmental parameters before and after the hospital was occupied with patients and staff. Characterizing and understanding factors that influence these building dynamics is vital for

  11. Spatial and Temporal Variations in Indoor Environmental Conditions, Human Occupancy, and Operational Characteristics in a New Hospital Building

    PubMed Central

    Ramos, Tiffanie; Dedesko, Sandra; Siegel, Jeffrey A.; Gilbert, Jack A.; Stephens, Brent

    2015-01-01

    The dynamics of indoor environmental conditions, human occupancy, and operational characteristics of buildings influence human comfort and indoor environmental quality, including the survival and progression of microbial communities. A suite of continuous, long-term environmental and operational parameters were measured in ten patient rooms and two nurse stations in a new hospital building in Chicago, IL to characterize the indoor environment in which microbial samples were taken for the Hospital Microbiome Project. Measurements included environmental conditions (indoor dry-bulb temperature, relative humidity, humidity ratio, and illuminance) in the patient rooms and nurse stations; differential pressure between the patient rooms and hallways; surrogate measures for human occupancy and activity in the patient rooms using both indoor air CO2 concentrations and infrared doorway beam-break counters; and outdoor air fractions in the heating, ventilating, and air-conditioning systems serving the sampled spaces. Measurements were made at 5-minute intervals over consecutive days for nearly one year, providing a total of ∼8×106 data points. Indoor temperature, illuminance, and human occupancy/activity were all weakly correlated between rooms, while relative humidity, humidity ratio, and outdoor air fractions showed strong temporal (seasonal) patterns and strong spatial correlations between rooms. Differential pressure measurements confirmed that all patient rooms were operated at neutral pressure. The patient rooms averaged about 100 combined entrances and exits per day, which suggests they were relatively lightly occupied compared to higher traffic environments (e.g., retail buildings) and more similar to lower traffic office environments. There were also clear differences in several environmental parameters before and after the hospital was occupied with patients and staff. Characterizing and understanding factors that influence these building dynamics is vital for

  12. Spatial and temporal variations in indoor environmental conditions, human occupancy, and operational characteristics in a new hospital building

    DOE PAGESBeta

    Ramos, Tiffanie; Dedesko, Sandra; Siegel, Jeffrey A.; Gilbert, Jack A.; Stephens, Brent

    2015-03-02

    The dynamics of indoor environmental conditions, human occupancy, and operational characteristics of buildings influence human comfort and indoor environmental quality, including the survival and progression of microbial communities. A suite of continuous, long-term environmental and operational parameters were measured in ten patient rooms and two nurse stations in a new hospital building in Chicago, IL to characterize the indoor environment in which microbial samples were taken for the Hospital Microbiome Project. Measurements included environmental conditions (indoor dry-bulb temperature, relative humidity, humidity ratio, and illuminance) in the patient rooms and nurse stations; differential pressure between the patient rooms and hallways; surrogatemore » measures for human occupancy and activity in the patient rooms using both indoor air CO₂ concentrations and infrared doorway beam-break counters; and outdoor air fractions in the heating, ventilating, and air-conditioning systems serving the sampled spaces. Measurements were made at 5-minute intervals over consecutive days for nearly one year, providing a total of ~8×10⁶ data points. Indoor temperature, illuminance, and human occupancy/activity were all weakly correlated between rooms, while relative humidity, humidity ratio, and outdoor air fractions showed strong temporal (seasonal) patterns and strong spatial correlations between rooms. Differential pressure measurements confirmed that all patient rooms were operated at neutral pressure. The patient rooms averaged about 100 combined entrances and exits per day, which suggests they were relatively lightly occupied compared to higher traffic environments (e.g., retail buildings) and more similar to lower traffic office environments. There were also clear differences in several environmental parameters before and after the hospital was occupied with patients and staff. Characterizing and understanding factors that influence these building dynamics is

  13. Temporal changes in the bacterial community of animal feces and their correlation with stable fly oviposition, larval development, and adult fitness

    PubMed Central

    Albuquerque, Thais A.; Zurek, Ludek

    2014-01-01

    Stable flies are blood-feeding insects with a great negative impact on animals world wide. Larvae develop primarily in animal manure and bacteria are essential for larval development; however, the principle of this dependence is not understood. We hypothesized that as the microbial community of animal manure changes over time, it plays an important role in stable fly fitness. Two-choice bioassays were conducted using 2 week old horse manure (control) and aging horse manure (fresh to 5 week old) to evaluate the effect of manure age on stable fly oviposition. Our data showed that fresh feces did not stimulate oviposition and that the attractiveness increased as manure aged but started to decline after 3 weeks. Bioassays assessing the effect of manure age at the time of oviposition on larval development demonstrated that 1–3 week old manure supported larval development significantly better than fresh, 4, and 5 week old manure. In addition, adult fitness (body size) was significantly higher in flies from 1 and 2 week old manure comparing to that of all other treatments. Analysis of the bacterial community of aging horse manure by 454-pyrosequencing of 16S rDNA revealed a great reduction in bacterial diversity and richness from fresh to 1–5 week old manure and a major shift from strict anaerobes in fresh manure to facultative anaerobes and strict aerobes in aged manure. Overall, the microbial community of 2 and 3 week old horse manure with its dominant bacterial taxa Rhizobium, Devosia, and Brevundimonas stimulated stable fly oviposition the most and provided a suitable habitat for larval development. These bacteria represent the candidates for studies focused on better understanding of stable fly – microbial interactions. PMID:25426108

  14. Temporal variatiions of Sea ice cover in the Baltic Sea derived from operational sea ice products used in NWP.

    NASA Astrophysics Data System (ADS)

    Lange, Martin; Paul, Gerhard; Potthast, Roland

    2014-05-01

    Sea ice cover is a crucial parameter for surface fluxes of heat and moisture over water areas. The isolating effect and the much higher albedo strongly reduces the turbulent exchange of heat and moisture from the surface to the atmosphere and allows for cold and dry air mass flow with strong impact on the stability of the whole boundary layer and consequently cloud formation as well as precipitation in the downstream regions. Numerical weather centers as, ECMWF, MetoFrance or DWD use external products to initialize SST and sea ice cover in their NWP models. To the knowledge of the author there are mainly two global sea ice products well established with operational availability, one from NOAA NCEP that combines measurements with satellite data, and the other from OSI-SAF derived from SSMI/S sensors. The latter one is used in the Ostia product. DWD additionally uses a regional product for the Baltic Sea provided by the national center for shipping and hydrografie which combines observations from ships (and icebreakers) for the German part of the Baltic Sea and model analysis from the hydrodynamic HIROMB model of the Swedish meteorological service for the rest of the domain. The temporal evolution of the three different products are compared for a cold period in Februar 2012. Goods and bads will be presented and suggestions for a harmonization of strong day to day jumps over large areas are suggested.

  15. Low-operating voltage and stable organic field-effect transistors with poly (methyl methacrylate) gate dielectric solution deposited from a high dipole moment solvent

    NASA Astrophysics Data System (ADS)

    Ukah, N. B.; Granstrom, J.; Sanganna Gari, R. R.; King, G. M.; Guha, S.

    2011-12-01

    A low-operating voltage and stable pentacene field-effect transistor (FET) employing thin low-dielectric constant gate layer of poly (methyl methacrylate) (PMMA) dissolved in propylene carbonate (PC) has been realized. This device exhibiting high field-effect mobility, a threshold voltage of -1 V, and a small sub-threshold slope at operating voltages below -3 V is compared with an FET cast from PMMA film dissolved in a low dipole moment solvent. The negligible hysteresis and excellent electrical stability of FETs under gate bias stress with the use of PC are traceable to the low density of trap states in PMMA bulk and at the interfaces.

  16. Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1998-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings (FBG) has been achieved by two methods: (1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element; (2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

  17. Stable CW Single Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by tWo methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback'. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

  18. Future Fitness of Female Insect Pests in Temporally Stable and Unstable Habitats and Its Impact on Habitat Utility as Refuges for Insect Resistance Management

    PubMed Central

    Caprio, Michael A.; Parker, C. D.; Schneider, John C.

    2009-01-01

    The long-term fitness of individuals is examined in complex and temporally dynamic ecosystems. We call this multigeneration fitness measure “future fitness”. Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) is a polyphagous insect that feeds on many wild and cultivated hosts. While four generations of H. zea occur during the cropping season in the U.S. Mid Southern agroecosysem, the latter two generations were of most interest, as corn (which has been largely nontransgenic in the Mid-South) dominates the first two generations in the cropping system. In simulations of the evolution of resistance to Bt-transgenic crops, cotton refuge areas were found to be significantly more effective than similar soybean acreages at delaying the evolution of resistance. Cotton is a suitable host for H. zea during two late summer generations, while a soybean field is suitable for only one of these generations, therefore soybean fields of other maturity groups were simulated as being attractive during the alternative generation. A hypothetical soybean variety was tested in which a single field would be attractive over both generations and it was found to be significantly more effective at delaying resistance than simulated conventional soybean varieties. Finally, the placement of individuals emerging at the start of the 3rd (first without corn) generation was simulated in either refuge cotton, conventional soybean and the hypothetical long attractive soybean and the mean number of offspring produced was measured at the end of the season. Although females in conventional and long soybean crops had the same expected fecundity, because of differences in temporal stability of the two crops, the long soybean simulations had significantly more H. zea individuals at the end of the season than the conventional soybean simulations. These simulations demonstrate that the long-term fecundity associated with an individual is dependent not only on the fecundity of that individual in its

  19. Spatial and temporal expression of vegetation and atmospheric variability from stable carbon and nitrogen isotope analysis of bat guano in the southern United States

    NASA Astrophysics Data System (ADS)

    Wurster, Christopher M.; McFarlane, Donald A.; Bird, Michael I.

    2007-07-01

    Stable isotopes of faeces contain information related to the animals feeding ecology. The use of stable isotope values from subfossil faeces as a palaeoenvironmental indicator depends on how faithfully the animal records their local environment. Here we present insectivorous bat guano δ 13C and δ 15N values from a precipitation gradient across the southern United States and northern Mexico to compare with local vegetation and climate. We find δ 13C values to be an excellent predictor of expected C 4/CAM vegetation, indicating that the bats are non-selective in their diet. Moreover, we find bat guano δ 13C values to be strongly correlated with summer precipitation amount and winter precipitation ratio. We also find evidence for a significant relationship with mean annual temperature. In general, we do not find δ 15N values to be related to any parameters along the climatic gradient we examined. Additionally, we measured δ 13C and δ 15N values of bulk guano deposited annually from 1968 to 1987 in a varved guano deposit at Eagle Creek Cave, Arizona. Neither δ 13C nor δ 15N values were significantly related to various local meteorological variables; however, we found δ 13C values of guano to be significantly related to drought and to the North American Monsoon indicating bat guano δ 13C values preserve an interpretable record of large-scale atmospheric variability.

  20. Superior optical limiting, stabilization, and spatio-temporal reshaping of ultrashort laser pulses in an opto-stable intrinsic polymer film.

    PubMed

    He, Guang S; Oh, Heong S; Prasad, Paras N

    2011-11-15

    A chemically modified poly(fluorene-alt-benzothiadiazole) (PFBT) polymer film is reported to exhibit high two-photon absorbing capability and chemical/physical stability upon the action of high-power laser pulses of ~780 nm wavelength and ~160 fs duration. A nonlinear transmission measurement is conducted by varying the input intensity from ~20 to ~600 GW/cm2, the corresponding nonlinear transmission of a ~70 μm thick film is reduced from ~0.8 to 0.18, indicating a superior optical limiting behavior. In the meantime, intensity fluctuation of laser pulses can be significantly reduced after passing through the same film sample. Based on the intensity-dependent nonlinear attenuation mechanism, a straightforward optical reshaping effect on spatio-temporal profiles of the laser pulses has also been demonstrated. PMID:22089587

  1. Frequency-stable operation of a diode-pumped continuous-wave RbTiOAsO(4) optical parametric oscillator.

    PubMed

    Scheidt, M; Beier, B; Boller, K J; Wallenstein, R

    1997-09-01

    Frequency-stable operation of a diode-pumped continuous-wave optical parametric oscillator (OPO) of RbTiOAsO(4) is demonstrated. Piezoelectric and fast electro-optic control of the optical length of the two-mirror OPO cavity (resonant for the pump and the idler waves) compensates for thermal changes in the refractive index of the OPO crystal (induced by absorption of pump light) and acoustic perturbations of the cavity length. Pumped by 405mW of the 810-nm output of a GaAlAs masterf-oscillator-tapered-amplifier diode laser system, the OPO generates a power-stable single-frequency signal wave at 1.24microm with an output of 84mW and a spectral bandwidth of less than 10MHz. PMID:18188215

  2. The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmasa)

    NASA Astrophysics Data System (ADS)

    Garofalo, A. M.; Burrell, K. H.; Eldon, D.; Grierson, B. A.; Hanson, J. M.; Holland, C.; Huijsmans, G. T. A.; Liu, F.; Loarte, A.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Solomon, W. M.; Turnbull, A. D.; Zeng, L.

    2015-05-01

    For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named "Super H-mode" because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

  3. A simple highly stable and temporally synchronizable Nd:glass laser oscillator delivering laser pulses of variable pulse duration from sub-nanosecond to few nanoseconds

    NASA Astrophysics Data System (ADS)

    Sharma, A. K.; Joshi, R. A.; Patidar, R. K.; Naik, P. A.; Gupta, P. D.

    2007-04-01

    A simple flash lamp pumped Nd:phosphate glass laser oscillator has been designed and set up delivering laser pulses of variable duration from ˜800 ps to 6 ns. It is based on Q-switching and full-wavelength cavity dumping and provides single laser pulse energy of 5 mJ and 11 mJ corresponding to pulse duration of ˜800 ps and 6 ns respectively at an electrical pump energy of 50 J. While the maximum pulse duration is governed by the cavity round trip time, the lower limit is decided by the switching speed of the high voltage pulse to the Pockels cell of the cavity dumper. Output laser pulses have shown enhanced pulse energy stability by dumping the cavity four round trips after the peak buildup. The laser pulses were synchronized with 250 ps positively chirped laser pulse train derived from an independent commercial cw mode locked Nd:fluorophosphate glass laser oscillator. The temporal jitter between these two pulses was measured to be ˜200 ps, limited by the speed of the electronics used.

  4. Interpretation of anthropogenic impacts (agriculture and urbanization) on tropical deltaic river network through the spatio-temporal variation of stable (N, O) isotopes of NO(-)3.

    PubMed

    Ta, Thi Thao; Le, Si Hung; Trinh, Hong Quan; Luu, Thi Nguyet Minh; Trinh, Anh Duc

    2016-01-01

    For the first time, the dual isotope approach was applied to trace the sources of impacts and to identify the governing biogeochemical processes in a river network in the tropical deltaic region of the Red River (Vietnam). Our long term surveys concluded that water in this river network was severely impacted by anthropogenic activities. Analysis has shown strong spatio-temporal variation of nitrate isotopes; ranges of δ(15)N-[Formula: see text] and δ(18)O-[Formula: see text] were from -5 to 15 ‰ and from -10 to 10 ‰, respectively. Average values of δ(15)N-[Formula: see text] and δ(18)O-[Formula: see text] in the dry season, when fertilizer is applied, were 3.54 and 3.15 ‰, respectively. In the rainy season, the values changed to 6.41 and -2.23 ‰, respectively. Denitrification and biological assimilation were active throughout the year, but were especially enhanced during fertilization time. Mineralization of domestic organic matter and consequent nitrification of mineralized [Formula: see text] were the dominant processes, particularly during the rainy period. PMID:26954849

  5. Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by two methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback. We coupled a nominal 935 run-wavelength Fabry-Perot laser diode to an ultra narrow band (18 pm) FBG. When tuned by varying its temperature, the laser wavelength is pulled toward the centerline of the Bragg grating, and the spectrum of the laser output is seen to fall into three discrete stability regimes as measured by the side-mode suppression ratio.

  6. The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmas

    SciTech Connect

    Garofalo, A. M. Burrell, K. H.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Turnbull, A. D.; Eldon, D.; Grierson, B. A.; Solomon, W. M.; Hanson, J. M.; Holland, C.; Huijsmans, G. T. A.; Liu, F.; Loarte, A.; Zeng, L.

    2015-05-15

    For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named “Super H-mode” because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

  7. Enhanced stable long-term operation of biotrickling filters treating VOCs by low-dose ozonation and its affecting mechanism on biofilm.

    PubMed

    Zhou, Qingwei; Zhang, Lili; Chen, Jianmeng; Luo, Yong; Zou, Haikui; Sun, Baochang

    2016-11-01

    For long-term operation of highly loaded biotrickling filters (BTFs), the prevention of excess biomass accumulation was essential for avoiding BTF failure. In this study, we proposed low-dose ozonation as a biomass control strategy to maintain high removal efficiencies of volatile organic compounds (VOCs) over extended operation of BTFs. To obtain an optimized biomass control strategy, the relative performance of five parallel BTFs receiving different ozone doses was determined, and the affecting mechanism of ozonation on biofilm was elucidated. Experimental results showed that the decline in ozone-free BTF performance began from day 150, which was correlated with excess biomass accumulation, abundant excretion of extracellular polymeric substances (EPS) and a decline in metabolic activity of biofilm over extended operation. Ozone of 5-10 mg m(-3) was effective in preventing excessive growth and uneven distribution of biomass, and eventually maintaining long-term stable operations. Ozone of over 20 mg m(-3) possibly inhibited microorganism growth severely, thereby deteriorating the elimination performance instead. Comparison of the biofilm EPS indicated that the presence of ozone reduce EPS contents to different extents, which was possibly beneficial for mass transfer and metabolic activity. Comparative community analysis showed that ozonation resulted in different microbial communities in the BTFs. Dyella was found to be the most abundant bacterial genera in all BTFs regardless of ozonation, indicating strong resistance to ozonation. Chryseobacterium and Burkholderia members were markedly enriched in the ozone-added biofilm, implying good adaptation to ozone presence. These findings provided an improved understanding of low-dose ozonation in maintaining a stable long-term operation of BTF. PMID:27494314

  8. Dynamics of an estuarine nursery ground: the spatio-temporal relationship between the river flow and the food web of the juvenile common sole ( Solea solea, L.) as revealed by stable isotopes analysis

    NASA Astrophysics Data System (ADS)

    Kostecki, C.; Le Loc'h, F.; Roussel, J.-M.; Desroy, N.; Huteau, D.; Riera, P.; Le Bris, H.; Le Pape, O.

    2010-07-01

    Estuaries are essential fish habitats because they provide nursery grounds for a number of marine species. Previous studies in the Bay of Vilaine (part of the Bay of Biscay, France) have underlined the estuarine dependence of juvenile common sole ( Solea solea, L.) and shown that the extent of sole nursery grounds was positively influenced by the variability of the river flow. In the present study, stable carbon and nitrogen isotopes were used to describe the trophic network until the young-of-the-year sole and to compare interannual variations in the dominant trophic pathways in the sole nursery areas in this bay. Particulate organic matter (POM), sediment organic matter (SOM), microphytobenthos, benthic invertebrate sole prey and young-of-the-year common sole were collected during the summer over 4 years characterised by contrasting river discharges. POM isotopic signatures were used to identify the origins of nutrient and organic matter assimilated into the estuarine food web through benthic organisms to juvenile common sole. Interannual spatial variations were found in the POM carbon stable isotope signatures, with the importance of these variations depending on the interannual fluctuations of the river flow. Moreover, the spatio-temporal variability of this POM isotopic signature was propagated along the food webs up to juvenile sole, confirming the central role of river discharge and terrigeneous subsidy input in the estuarine benthic food web in determining the size of the sole nursery habitat.

  9. Temporal behaviour of a corner separation in a radial vaned diffuser of a centrifugal compressor operating near surge

    NASA Astrophysics Data System (ADS)

    Marsan, A.; Trébinjac, I.; Coste, S.; Leroy, G.

    2013-12-01

    The temporal behaviour of a flow separation in the hub-suction side corner of a transonic diffuser is studied thanks to unsteady numerical simulations based on the phase-lagged approach. The validity of the numerical results is confirmed by comparison with experimental unsteady pressure measurements. An analysis of the instantaneous skin-friction pattern and particles trajectories is presented. It highlights the topology of the separation and its temporal behaviour. The major result is that, despite of a highly time-dependent core flow, the separation is found to be a "fixed unsteady separation" characterized by a fixed location of the main saddle of the separation but an extent of the stall region modulated by the pressure waves induced by the impeller-diffuser interaction.

  10. Temporal Non-locality

    NASA Astrophysics Data System (ADS)

    Filk, Thomas

    2013-04-01

    In this article I investigate several possibilities to define the concept of "temporal non-locality" within the standard framework of quantum theory. In particular, I analyze the notions of "temporally non-local states", "temporally non-local events" and "temporally non-local observables". The idea of temporally non-local events is already inherent in the standard formalism of quantum mechanics, and Basil Hiley recently defined an operator in order to measure the degree of such a temporal non-locality. The concept of temporally non-local states enters as soon as "clock-representing states" are introduced in the context of special and general relativity. It is discussed in which way temporally non-local measurements may find an interesting application for experiments which test temporal versions of Bell inequalities.

  11. Stable silylenes.

    PubMed

    Haaf, M; Schmedake, T A; West, R

    2000-10-01

    The field of stable silylene research has grown dramatically since the first isolation of a stable silylene in 1994. Prior to 1994, silylenes existed only as reactive intermediates, isolable only in low-temperature matrixes. Since then, several stable silylenes have been synthesized, some in fact showing remarkable thermal stability. This Account highlights the developments in stable silylene chemistry, including theoretical and experimental studies attempting to explain the remarkable stability of the silylenes as well as the rapidly expanding reaction chemistry of the stable silylenes. PMID:11041835

  12. Analysing the Advantages of High Temporal Resolution Geostationary MSG SEVIRI Data Compared to Polar Operational Environmental Satellite Data for Land Surface Monitoring in Africa

    NASA Technical Reports Server (NTRS)

    Fensholt, R.; Anyamba, A.; Huber, S.; Proud, S. R.; Tucker, C. J.; Small, J.; Pak, E.; Rasmussen, M. O.; Sandholt, I.; Shisanya, C.

    2011-01-01

    Since 1972, satellite remote sensing of the environment has been dominated by polar-orbiting sensors providing useful data for monitoring the earth s natural resources. However their observation and monitoring capacity are inhibited by daily to monthly looks for any given ground surface which often is obscured by frequent and persistent cloud cover creating large gaps in time series measurements. The launch of the Meteosat Second Generation (MSG) satellite into geostationary orbit has opened new opportunities for land surface monitoring. The Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument on-board MSG with an imaging capability every 15 minutes which is substantially greater than any temporal resolution that can be obtained from existing polar operational environmental satellites (POES) systems currently in use for environmental monitoring. Different areas of the African continent were affected by droughts and floods in 2008 caused by periods of abnormally low and high rainfall, respectively. Based on the effectiveness of monitoring these events from Earth Observation (EO) data the current analyses show that the new generation of geostationary remote sensing data can provide higher temporal resolution cloud-free (less than 5 days) measurements of the environment as compared to existing POES systems. SEVIRI MSG 5-day continental scale composites will enable rapid assessment of environmental conditions and improved early warning of disasters for the African continent such as flooding or droughts. The high temporal resolution geostationary data will complement existing higher spatial resolution polar-orbiting satellite data for various dynamic environmental and natural resource applications of terrestrial ecosystems.

  13. High-speed highly temperature stable 980 nm VCSELs operating at 25 Gb/s at up to 85 °C for short reach optical interconnects

    NASA Astrophysics Data System (ADS)

    Mutig, Alex; Lott, James A.; Blokhin, Sergey A.; Moser, Philip; Wolf, Philip; Hofmann, Werner; Nadtochiy, Alexey M.; Bimberg, Dieter

    2011-03-01

    The progressive penetration of optical communication links into traditional copper interconnect markets greatly expands the applications of vertical cavity surface emitting lasers (VCSELs) for the next-generation of board-to-board, moduleto- module, chip-to-chip, and on-chip optical interconnects. Stability of the VCSEL parameters at high temperatures is indispensable for such applications, since these lasers typically reside directly on or near integrated circuit chips. Here we present 980 nm oxide-confined VCSELs operating error-free at bit rates up to 25 Gbit/s at temperatures as high as 85 °C without adjustment of the drive current and peak-to-peak modulation voltage. The driver design is therefore simplified and the power consumption of the driver electronics is lowered, reducing the production and operational costs. Small and large signal modulation experiments at various temperatures from 20 up to 85 °C for lasers with different oxide aperture diameters are presented in order to analyze the physical processes controlling the performance of the VCSELs. Temperature insensitive maximum -3 dB bandwidths of around 13-15 GHz for VCSELs with aperture diameters of 10 μm and corresponding parasitic cut-off frequencies exceeding 22 GHz are observed. Presented results demonstrate the suitability of our VCSELs for practical high speed and high temperature stable short-reach optical links.

  14. Female mini-pig performance of temporal response differentiation, incremental repeated acquisition, and progressive ratio operant tasks.

    PubMed

    Ferguson, Sherry A; Gopee, Neera V; Paule, Merle G; Howard, Paul C

    2009-01-01

    Increased knowledge of the cognitive abilities of mini-pigs is needed due to their increasing use in behavioral neuroscience research. Here, six female Yucatan mini-pigs performed tasks thought to measure timing behavior (temporal response differentiation, TRD), learning (incremental repeated acquisition, IRA), and motivation (progressive ratio, PR). Daily 30-min sessions for food reinforcers required a lever press be maintained for at least 10 but no longer than 14s (TRD), learning a new sequence of lever presses each test day (IRA) or an escalating number of presses for subsequent reinforcers (PR). All animals performed PR two days/week while three performed TRD five days/week and the other three performed IRA five days/week. Over the four test weeks, no animal completed TRD training and only one appeared to progress. For this task, lever press maintenance appeared difficult since by choice, the pigs used a front hoof, rather than the snout, to press the lever. IRA subjects showed gradually increasing performance with response rates comparable to those of rats but below those of children and monkeys and accuracy below that for rats. PR response rates were higher than those typically reported for rats, but lower than for adult rhesus monkeys or children. Physical differences in the way that each species responds likely account for these differences. PMID:18804519

  15. Revisiting the use of δ15N in meso-scale studies of marine food webs by considering spatio-temporal variations in stable isotopic signatures - The case of an open ecosystem: The Bay of Biscay (North-East Atlantic)

    NASA Astrophysics Data System (ADS)

    Chouvelon, T.; Spitz, J.; Caurant, F.; Mèndez-Fernandez, P.; Chappuis, A.; Laugier, F.; Le Goff, E.; Bustamante, P.

    2012-08-01

    Most of the recent framework directives and environmental policies argue for the development and the use of indicators - notably trophodynamic indicators - that should be able to follow ecosystems' evolution in space and time, particularly under anthropogenic perturbations. In the last decades, the use of stable carbon and nitrogen isotopes ratios has increased exponentially, particularly in studies of marine ecosystems' trophic structure and functioning. This method is principally based on the assumption that the isotopic composition of a consumer directly reflects that of its food. Nevertheless, few studies have attempted to define the limits of this tool, before using it and drawing ecological conclusions from isotopic analysis. This study aimed to assess the importance of considering spatio-temporal variations in isotopic signatures of consumers when using δ13C and especially δ15N values in open ecosystems with complex food webs, using the Bay of Biscay (North-East Atlantic) as a case study. To this end, more than 140 species from this marine ecosystem were analysed for the isotopic signatures in their muscle tissue. They were sampled from coastal to oceanic and deep-sea areas and at different latitudes, to evaluate spatial variations of isotopic signatures. Selected species were also sampled over several years and in two seasons to account for inter-annual and seasonal variations. In the Bay of Biscay temperate ecosystem, which is subject to both coastal and oceanic influences - two main river inputs and upwelling areas - , δ13C and δ15N values significantly decreased from inshore to offshore species, and to a lesser extent from benthic to pelagic organisms. River discharges appeared to be the first factor influencing δ13C and δ15N values in consumers. From the important spatial variations detected in δ15N values in particular, we suggest that in such contrasted ecosystem, nitrogen isotopic ratios may also be revisited as an indicator of the feeding

  16. How Stable Is Stable? Function versus Community Composition

    PubMed Central

    Fernández, Ana; Huang, Suiying; Seston, Sherry; Xing, Jian; Hickey, Robert; Criddle, Craig; Tiedje, James

    1999-01-01

    The microbial community dynamics of a functionally stable, well-mixed, methanogenic reactor fed with glucose were analyzed over a 605-day period. The reactor maintained constant pH and chemical oxygen demand removal during this period. Thirty-six rrn clones from each of seven sampling events were analyzed by amplified ribosomal DNA restriction analysis (ARDRA) for the Bacteria and Archaea domains and by sequence analysis of dominant members of the community. Operational taxonomic units (OTUs), distinguished as unique ARDRA patterns, showed reproducible distribution for three sample replicates. The highest diversity was observed in the Bacteria domain. The 16S ribosomal DNA Bacteria clone library contained 75 OTUs, with the dominant OTU accounting for 13% of the total clones, but just 21 Archaea OTUs were found, and the most prominent OTU represented 50% of the clones from the respective library. Succession in methanogenic populations was observed, and two periods were distinguished: in the first, Methanobacterium formicicum was dominant, and in the second, Methanosarcina mazei and a Methanobacterium bryantii-related organism were dominant. Higher variability in Bacteria populations was detected, and the temporal OTU distribution suggested a chaotic pattern. Although dominant OTUs were constantly replaced from one sampling point to the next, phylogenetic analysis indicated that inferred physiologic changes in the community were not as dramatic as were genetic changes. Seven of eight dominant OTUs during the first period clustered with the spirochete group, although a cyclic pattern of substitution occurred among members within this order. A more flexible community structure characterized the second period, since a sequential replacement of a Eubacterium-related organism by an unrelated deep-branched organism and finally by a Propionibacterium-like species was observed. Metabolic differences among the dominant fermenters detected suggest that changes in carbon and

  17. Operations

    ERIC Educational Resources Information Center

    Wilkins, Jesse L. M.; Norton, Anderson; Boyce, Steven J.

    2013-01-01

    Previous research has documented schemes and operations that undergird students' understanding of fractions. This prior research was based, in large part, on small-group teaching experiments. However, written assessments are needed in order for teachers and researchers to assess students' ways of operating on a whole-class scale. In this…

  18. Stable compactifications

    SciTech Connect

    Accetta, F.S.; Gleiser, M.; Holman, R.; Kolb, E.W.

    1986-03-01

    We show that compactifications of theories with extra dimensions are unstable if due to monopole configurations of an antisymmetric tensor field balanced against one-loop Casimir corrections. In the case of ten dimensional supergravity, it is possible, at least for a portion of the phase space, to achieve a stable compactification without fine-tuning by including the contribution of fermionic condensates to the monopole configurations. 23 refs., 2 figs.

  19. Analysis of the sensitivity to rainfall spatio-temporal variability of an operational urban rainfall-runoff model in a multifractal framework

    NASA Astrophysics Data System (ADS)

    Gires, A.; Tchiguirinskaia, I.; Schertzer, D. J.; Lovejoy, S.

    2011-12-01

    In large urban areas, storm water management is a challenge with enlarging impervious areas. Many cities have implemented real time control (RTC) of their urban drainage system to either reduce overflow or limit urban contamination. A basic component of RTC is hydraulic/hydrologic model. In this paper we use the multifractal framework to suggest an innovative way to test the sensitivity of such a model to the spatio-temporal variability of its rainfall input. Indeed the rainfall variability is often neglected in urban context, being considered as a non-relevant issue at the scales involve. Our results show that on the contrary the rainfall variability should be taken into account. Universal multifractals (UM) rely on the concept of multiplicative cascade and are a standard tool to analyze and simulate with a reduced number of parameters geophysical processes that are extremely variable over a wide range of scales. This study is conducted on a 3 400 ha urban area located in Seine-Saint-Denis, in the North of Paris (France). We use the operational semi-distributed model that was calibrated by the local authority (Direction Eau et Assainnissement du 93) that is in charge of urban drainage. The rainfall data comes from the C-Band radar of Trappes operated by Météo-France. The rainfall event of February 9th, 2009 was used. A stochastic ensemble approach was implemented to quantify the uncertainty on discharge associated to the rainfall variability occurring at scales smaller than 1 km x 1 km x 5 min that is usually available with C-band radar networks. An analysis of the quantiles of the simulated peak flow showed that the uncertainty exceeds 20 % for upstream links. To evaluate a potential gain from a direct use of the rainfall data available at the resolution of X-band radar, we performed similar analysis of the rainfall fields of the degraded resolution of 9 km x 9 km x 20 min. The results show a clear decrease in uncertainty when the original resolution of C

  20. Studies and optimization of Pohang Light Source-II superconducting radio frequency system at stable top-up operation with beam current of 400 mA

    SciTech Connect

    Joo, Youngdo Yu, Inha; Park, Insoo; Chun, Myunghwan; Lee, Byung-Joon; Hwang, Ilmoon; Ha, Taekyun; Shin, Seunghwan; Sohn, Younguk

    2014-12-21

    After three years of upgrading work, the Pohang Light Source-II (PLS-II) is now successfully operating. The final quantitative goal of PLS-II is a top-up user-service operation with beam current of 400 mA to be completed by the end of 2014. During the beam store test up to 400 mA in the storage ring (SR), it was observed that the vacuum pressure around the radio frequency (RF) window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. Although available beam current is enhanced by setting a higher RF accelerating voltage, it is better to keep the RF accelerating voltage as low as possible in the long time top-up operation. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. In our simulation, an equivalent physical modeling was developed using a finite-difference time-domain code. The simulation revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window, which comes with the rapid increase of window vacuum pressure. The RF accelerating voltage of PLS-II RF system was set to 4.95 MV, which was estimated using the maximum available beam current that works as a function of RF voltage, and the top-up operation test with the beam current of 400 mA was successfully carried out.

  1. Highly stable and efficient erbium-doped 2.8 microm all fiber laser.

    PubMed

    Bernier, Martin; Faucher, Dominic; Caron, Nicolas; Vallée, Réal

    2009-09-14

    We demonstrate the efficient and stable CW laser operation at 2.824 microm of a diode-pumped erbium-doped fluoride fiber laser employing an intracore fiber Bragg grating high reflector. An output power of 5 W and an optical-to-optical conversion efficiency of 32% are reported. The temporal and spectral stability of the laser represent a significant improvement over previous work. This report paves the way to the commercialization of compact and stable fiber lasers for spectroscopic and medical applications. PMID:19770912

  2. Temporal steering inequality

    NASA Astrophysics Data System (ADS)

    Chen, Yueh-Nan; Li, Che-Ming; Lambert, Neill; Chen, Shin-Liang; Ota, Yukihiro; Chen, Guang-Yin; Nori, Franco

    2014-03-01

    Quantum steering is the ability to remotely prepare different quantum states by using entangled pairs as a resource. Very recently, the concept of steering has been quantified with the use of inequalities, leading to substantial applications in quantum information and communication science. Here, we highlight that there exists a natural temporal analog of the steering inequality when considering measurements on a single object at different times. We give nontrivial operational meaning to violations of this temporal inequality by showing that it is connected to the security bound in the Bennett-Brassard 1984 protocol and thus may have applications in quantum communication.

  3. Stable, high-order SBP-SAT finite difference operators to enable accurate simulation of compressible turbulent flows on curvilinear grids, with application to predicting turbulent jet noise

    NASA Astrophysics Data System (ADS)

    Byun, Jaeseung; Bodony, Daniel; Pantano, Carlos

    2014-11-01

    Improved order-of-accuracy discretizations often require careful consideration of their numerical stability. We report on new high-order finite difference schemes using Summation-By-Parts (SBP) operators along with the Simultaneous-Approximation-Terms (SAT) boundary condition treatment for first and second-order spatial derivatives with variable coefficients. In particular, we present a highly accurate operator for SBP-SAT-based approximations of second-order derivatives with variable coefficients for Dirichlet and Neumann boundary conditions. These terms are responsible for approximating the physical dissipation of kinetic and thermal energy in a simulation, and contain grid metrics when the grid is curvilinear. Analysis using the Laplace transform method shows that strong stability is ensured with Dirichlet boundary conditions while weaker stability is obtained for Neumann boundary conditions. Furthermore, the benefits of the scheme is shown in the direct numerical simulation (DNS) of a Mach 1.5 compressible turbulent supersonic jet using curvilinear grids and skew-symmetric discretization. Particularly, we show that the improved methods allow minimization of the numerical filter often employed in these simulations and we discuss the qualities of the simulation.

  4. Temporal networks

    NASA Astrophysics Data System (ADS)

    Holme, Petter; Saramäki, Jari

    2012-10-01

    A great variety of systems in nature, society and technology-from the web of sexual contacts to the Internet, from the nervous system to power grids-can be modeled as graphs of vertices coupled by edges. The network structure, describing how the graph is wired, helps us understand, predict and optimize the behavior of dynamical systems. In many cases, however, the edges are not continuously active. As an example, in networks of communication via e-mail, text messages, or phone calls, edges represent sequences of instantaneous or practically instantaneous contacts. In some cases, edges are active for non-negligible periods of time: e.g., the proximity patterns of inpatients at hospitals can be represented by a graph where an edge between two individuals is on throughout the time they are at the same ward. Like network topology, the temporal structure of edge activations can affect dynamics of systems interacting through the network, from disease contagion on the network of patients to information diffusion over an e-mail network. In this review, we present the emergent field of temporal networks, and discuss methods for analyzing topological and temporal structure and models for elucidating their relation to the behavior of dynamical systems. In the light of traditional network theory, one can see this framework as moving the information of when things happen from the dynamical system on the network, to the network itself. Since fundamental properties, such as the transitivity of edges, do not necessarily hold in temporal networks, many of these methods need to be quite different from those for static networks. The study of temporal networks is very interdisciplinary in nature. Reflecting this, even the object of study has many names-temporal graphs, evolving graphs, time-varying graphs, time-aggregated graphs, time-stamped graphs, dynamic networks, dynamic graphs, dynamical graphs, and so on. This review covers different fields where temporal graphs are considered

  5. Stable Multibubble Sonoluminescence Bubble Patterns

    SciTech Connect

    Posakony, Gerald J.; Greenwood, Lawrence R.; Ahmed, Salahuddin

    2006-06-30

    Multibubble standing wave patterns can be generated from a flat piezoceramic transducer element propagating into water. By adding a second transducer positioned at 90 degrees from the transducer generating the standing wave, a 3-dimensional volume of stable single bubbles can be established. Further, the addition of the second transducer stabilizes the bubble pattern so that individual bubbles may be studied. The size of the bubbles and the separation of the standing waves depend on the frequency of operation. Two transducers, operating at frequencies above 500 kHz, provided the most graphic results for the configuration used in this study. At these frequencies stable bubbles exhibit a bright sonoluminescence pattern. Whereas stable SBSL is well-known, stable MBSL has not been previously reported. This paper includes discussions of the acoustic responses, standing wave patterns, and pictorial results of the separation of individual bubble of sonoluminescence in a multibubble sonoluminescence environment.

  6. Temporal naturalism

    NASA Astrophysics Data System (ADS)

    Smolin, Lee

    2015-11-01

    Two people may claim both to be naturalists, but have divergent conceptions of basic elements of the natural world which lead them to mean different things when they talk about laws of nature, or states, or the role of mathematics in physics. These disagreements do not much affect the ordinary practice of science which is about small subsystems of the universe, described or explained against a background, idealized to be fixed. But these issues become crucial when we consider including the whole universe within our system, for then there is no fixed background to reference observables to. I argue here that the key issue responsible for divergent versions of naturalism and divergent approaches to cosmology is the conception of time. One version, which I call temporal naturalism, holds that time, in the sense of the succession of present moments, is real, and that laws of nature evolve in that time. This is contrasted with timeless naturalism, which holds that laws are immutable and the present moment and its passage are illusions. I argue that temporal naturalism is empirically more adequate than the alternatives, because it offers testable explanations for puzzles its rivals cannot address, and is likely a better basis for solving major puzzles that presently face cosmology and physics. This essay also addresses the problem of qualia and experience within naturalism and argues that only temporal naturalism can make a place for qualia as intrinsic qualities of matter.

  7. Investigation of spatio-temporal variability of water uptake in a groundwater-dependent ecosystem using a stable isotope approach (δ18O, δ2H): Pfyn Forest, Switzerland

    NASA Astrophysics Data System (ADS)

    Bertrand, G.; Masini, J.; Goldscheider, N.; Gobat, J. M.; Hunkeler, D.

    2012-04-01

    total humidity of soil, this could be due to rapid infiltration and/or fractionation mainly under equilibrium, i.e. with a relatively high atmospheric humidity, what is possible under forest canopy. Plant water is located under the LMWL in September 2010 when the soil was relatively drought. This evaporative signature could be a clue of water stress. More investigations are however needed to check if this parameter can be used routinely to address water stress. - Secondly, through an analysis of variance, data reveal that at the ecosystem scale, water uptake depends on the site (type of soil, surrounding vegetation, distance from the river), on the growing status (non growing, flowering, mature, water stress) and on the species (poplar, willow, alder, pine). - At last, when focusing at the temporal variability for some individuals, it appears that both rainwater and groundwater may participate to water uptake. The water uptake patterns seem more complicated in mature areas (far from the riverbed) than in frequently flooded zones. This could be due to a more complex soil texture patchwork in the former, and a globally finer soil texture. In particular, it appears that groundwater may sometimes replace rainwater through capillary rise during warm periods.

  8. Stable Fly Research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adult stable flies feed on the blood of humans, pets and livestock, inflicting painful bites. Stable flies need one and sometimes two bloodmeals each day to develop their eggs. Unlike mosquitoes where only the females bloodfeed, both male and female stable flies require blood to reproduce. Stable fl...

  9. Temporal dark polariton solitons

    NASA Astrophysics Data System (ADS)

    Kartashov, Yaroslav V.; Skryabin, Dmitry V.

    2016-04-01

    We predict that strong coupling between waveguide photons and excitons of quantum well embedded into waveguide results in the formation of hybrid dark and anti-dark light-matter solitons. Such temporal solitons exist due to interplay between repulsive excitonic nonlinearity and giant group velocity dispersion arising in the vicinity of excitonic resonance. Such fully conservative states do not require external pumping to counteract losses and form continuous families parameterized by the power-dependent phase shift and velocity of their motion. Dark solitons are stable in the considerable part of their existence domain, while anti-dark solitons are always unstable. Both families exist outside forbidden frequency gap of the linear system.

  10. Temporal dark polariton solitons.

    PubMed

    Kartashov, Yaroslav V; Skryabin, Dmitry V

    2016-04-15

    We predict that strong coupling between waveguide photons and excitons of quantum well embedded into waveguide results in the formation of hybrid-dark and antidark light-matter solitons. Such temporal solitons exist due to interplay between repulsive excitonic nonlinearity and giant group-velocity dispersion arising in the vicinity of excitonic resonance. Such fully conservative states do not require external pumping to counteract losses and form continuous families parameterized by the power-dependent phase shift and velocity of their motion. Dark solitons are stable in the considerable part of their existence domain, while antidark solitons are always unstable. Both families exist outside the forbidden frequency gap of the linear system. PMID:27082338

  11. Magnetotelluric Data, Stable Distributions and Stable Regression

    NASA Astrophysics Data System (ADS)

    Chave, A. D.

    2013-12-01

    The author has noted for many years that the residuals from robust or bounded influence estimates of the magnetotelluric response function are systematically long tailed compared to a Gaussian or Rayleigh distribution. Consequently, the standard statistical model of a Gaussian core contaminated by a fraction of outlying data is not really valid. However, the typical result is an improvement on ordinary least squares, and has become standard in the electromagnetic induction community. A recent re-evaluation of the statistics of magnetotelluric response function estimation has shown that, in almost all cases, the residuals are alpha stable rather than Gaussian. Alpha stable distributions are characterized by four parameters: a shape parameter lying on (0, 2], a skewness parameter, a scale parameter and a location parameter, and cannot be expressed in closed form except for a few special cases. When the shape parameter is 2, the result is Gaussian, but when it is smaller the resulting distribution has infinite variance. Typical magnetotelluric residuals are alpha stable with a shape parameter lying between 1 and 2. This suggests that robust methods improve response function estimates by eliminating data corresponding to the largest stable residuals while leaving the bulk of the population alone. A better statistical approach is based on stable regression that directly accommodates the actual residual distribution without eliminating the most extreme ones. This paper will introduce such an algorithm, and illustrate its functionality with a variety of magnetotelluric data. Further work remains to produce a robust stable regression algorithm that will eliminate real outliers such as lightning strikes or instrument problems without affecting the bulk stable population. Stable distributions are intimately associated with fractional derivative physical processes. Since the Maxwell equations and the constitutive relations pertaining to the earth do not contain any fractional

  12. Angina Pectoris (Stable Angina)

    MedlinePlus

    ... Pressure High Blood Pressure Tools & Resources Stroke More Angina Pectoris (Stable Angina) Updated:Aug 24,2016 You may have heard the term “angina pectoris” or “stable angina” in your doctor’s office, but ...

  13. Temporal logics meet telerobotics

    NASA Technical Reports Server (NTRS)

    Rutten, Eric; Marce, Lionel

    1989-01-01

    The specificity of telerobotics being the presence of a human operator, decision assistance tools are necessary for the operator, especially in hostile environments. In order to reduce execution hazards due to a degraded ability for quick and efficient recovery of unexpected dangerous situations, it is of importance to have the opportunity, amongst others, to simulate the possible consequences of a plan before its actual execution, in order to detect these problematic situations. Hence the idea of providing the operator with a simulator enabling him to verify the temporal and logical coherence of his plans. Therefore, the power of logical formalisms is used for representation and deduction purposes. Starting from the class of situations that are represented, a STRIPS (the STanford Research Institute Problem Solver)-like formalism and its underlying logic are adapted to the simulation of plans of actions in time. The choice of a temporal logic enables to build a world representation, on which the effects of plans, grouping actions into control structures, will be transcribed by the simulation, resulting in a verdict and information about the plan's coherence.

  14. Trans-mediastinal gunshot wounds: are "stable" patients really stable?

    PubMed

    Nagy, Kimberly K; Roberts, Roxanne R; Smith, Robert F; Joseph, Kimberly T; An, Gary C; Bokhari, Faran; Barrett, John

    2002-10-01

    Gunshot wounds that traverse the mediastinum frequently cause serious injury to the cardiac, vascular, pulmonary, and digestive structures contained within. Most patients present with unstable vital signs signifying the need for emergency operation. An occasional patient will present with stable vital signs. Work-ups for such a patient may range from surgical exploration to radiographic and endoscopic testing to mere observation. We report our experience with diagnostic work-up of the stable patient with a transmediastinal gunshot wound. All stable patients who present to our urban level I trauma center following a transmediastinal gunshot wound undergo diagnostic work-up consisting of chest radiograph, cardiac ultrasound, angiography, esophagoscopy, barium swallow, and bronchoscopy. The work-up is dependent on the trajectory of the missile. Information on these patients is kept in a prospective database maintained by the trauma attending physicians. This database was analyzed and comparisons were made using Student's t-test and the Fisher exact c2 as appropriate. Over a 68-month period, 50 stable patients were admitted following a transmediastinal gunshot wound. All of these patients had a chest radiograph followed by one or more of the above tests. 8 patients (16%) were found to have a mediastinal injury (4 cardiac, 3 vascular, and 1 tracheo-esophageal) requiring urgent operation (group 1). The remaining 42 patients (84%) did not have a mediastinal injury (group 2). There was no difference between groups with respect to blood pressure, pulse, respiratory rate, pH, base deficit, or initial chest tube output. There was one death in each group, and three complications in group 2. Patients may appear stable following a transmediastinal gunshot wound, even when they have life-threatening injuries. There is no difference in vital signs, blood gas, or hemothorax to indicate which patients have serious injuries. We advocate continued aggressive work-up of these patients

  15. Applying temporal joins to clinical databases.

    PubMed Central

    O'Connor, M. J.; Tu, S. W.; Musen, M. A.

    1999-01-01

    Clinical databases typically contain a significant amount of temporal information, information that is often crucial in medical decision-support systems. Most recent clinical information systems use the relational model when working with this information. Although these systems have reasonably well-defined semantics for temporal queries on a single relational table, many do not fully address the complex semantics of operations involving multiple temporal tables. Such operations can arise frequently in queries on clinical databases. This paper describes the issues encountered when joining a set of temporal tables, and outlines how such joins are far more complex than non-temporal ones. We describe the semantics of temporal joins in a query management system called Chronus II, a system we have developed to assist in evaluating patients for clinical trials. PMID:10566376

  16. The whole is faster than its parts: evidence for temporally independent attention to distinct spatial locations.

    PubMed

    Clement, Andrew; Matthews, Nestor

    2016-02-01

    Behavioral and electrophysiological evidence suggests that visual attention operates in parallel at distinct spatial locations and samples the environment in periodic episodes. This combination of spatial and temporal characteristics raises the question of whether attention samples locations in a phase-locked or temporally independent manner. If attentional sampling rates were phase locked, attention would be limited by a global sampling rate. However, if attentional sampling rates were temporally independent, they could operate additively to sample higher rates of information. We tested these predictions by requiring participants to identify targets in 2 or 4 rapid serial visual presentation (RSVP) streams, synchronized or asynchronized to manipulate the rate of new information globally (across streams). Identification accuracy exhibited little or no change when the global rate of new information doubled from 7.5 to 15 Hz (Experiment 1) or quadrupled to 30 Hz (Experiment 2). This relatively stable identification accuracy occurred even though participants reliably discriminated 7.5 Hz synchronous displays from displays globally asynchronized at 15 and 30 Hz (Metamer Control Experiment). Identification accuracy in the left visual field also significantly exceeded that in the right visual field. Overall, our results are consistent with temporally independent attention across distinct spatial locations and support previous reports of a right parietal "when" pathway specialized for temporal attention. PMID:26603040

  17. Stable Gain-Switched Thulium Fiber Laser With 140-nm Tuning Range

    NASA Astrophysics Data System (ADS)

    Wang, Fengqiu; Meng, Yafei; Kelleher, Edmund; Guo, Guoxiang; Li, Yao; Xu, Yongbing; Zhu, Shining

    2016-06-01

    We demonstrate a gain-switched thulium fiber laser that can be continuously tuned over 140 nm, while maintaining stable nanosecond single-pulse operation. To the best of our knowledge, this system represents the broadest tuning range for a gain-switched fiber laser. The system simplicity and wideband wavelength tunability combined with the ability to control the temporal characteristics of the gain-switched pulses mean this is a versatile source highly suited to a wide range of applications in the eye-safe region of the infrared, including spectroscopy, sensing and material processing, as well as being a practical seed source for pumping nonlinear processes.

  18. Temporal mapping and analysis

    NASA Technical Reports Server (NTRS)

    O'Hara, Charles G. (Inventor); Shrestha, Bijay (Inventor); Vijayaraj, Veeraraghavan (Inventor); Mali, Preeti (Inventor)

    2011-01-01

    A compositing process for selecting spatial data collected over a period of time, creating temporal data cubes from the spatial data, and processing and/or analyzing the data using temporal mapping algebra functions. In some embodiments, the temporal data cube is creating a masked cube using the data cubes, and computing a composite from the masked cube by using temporal mapping algebra.

  19. Stable isotope laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Becker, J. F.; Yaldaei, Ramil; Mckay, Christopher P.

    1989-01-01

    Recent advances in semiconductor laser technology have produced a reliable lightweight device ideally suited for a spacecraft high resolution molecular spectrometer. Lead-salt tunable diode lasers (TDL) emit in several spectral modes, each with a very narrow linewidth of -0.0003/cm. This spectral resolution is much narrower than typical Doppler broadened molecular linewidths in the mid-IR range. Thus it is possible to detect individual rotational lines within the vibrational band and measure their intensity, which can be used to determine gas concentration. The narrow spectral lines of any impurity gas tend to lie between the narrow lines of the gas of interest. This represents a major advantage over the accepted gas chromatograph mass spectrometer (GCMS) technique for measuring gas concentrations and isotope ratios. The careful and extensive gas purification procedures required to remove impurities for reliable GCMS measurements will not be required for an IR laser gas analysis. The infrared laser gas analysis technique is being developed to measure stable isotopic ratios of gases such as CO2, CH4, N2O, and NH3. This will eventually lead to development of instruments capable of in situ istopic measurements on planets such as Mars. The carbon (C-12, C-13) isotope ratio is indicative of the type of carbon fixation mechanisms (e.g., photosynthesis, respiration) in operation on a planet, while the nitrogen (N-14, N-15) isotope ratio can probably be used to date nitrogen-bearing Martian samples. The absorbance ratio of two adjacent lines of CO2 in the 2300/cm (4.3 micron) region of the spectrum was measured. The precision of the measurement is presently better than 1 percent and significant improvement is anticipated as rapid sweep-integration techniques and computer controlled data acquistion capabilities are incorporated.

  20. Stable isotope laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Becker, J. F.; Yaldaei, Ramil; McKay, Christopher P.

    1989-03-01

    Recent advances in semiconductor laser technology have produced a reliable lightweight device ideally suited for a spacecraft high resolution molecular spectrometer. Lead-salt tunable diode lasers (TDL) emit in several spectral modes, each with a very narrow linewidth of -0.0003/cm. This spectral resolution is much narrower than typical Doppler broadened molecular linewidths in the mid-IR range. Thus it is possible to detect individual rotational lines within the vibrational band and measure their intensity, which can be used to determine gas concentration. The narrow spectral lines of any impurity gas tend to lie between the narrow lines of the gas of interest. This represents a major advantage over the accepted gas chromatograph mass spectrometer (GCMS) technique for measuring gas concentrations and isotope ratios. The careful and extensive gas purification procedures required to remove impurities for reliable GCMS measurements will not be required for an IR laser gas analysis. The infrared laser gas analysis technique is being developed to measure stable isotopic ratios of gases such as CO2, CH4, N2O, and NH3. This will eventually lead to development of instruments capable of in situ istopic measurements on planets such as Mars. The carbon (C-12, C-13) isotope ratio is indicative of the type of carbon fixation mechanisms (e.g., photosynthesis, respiration) in operation on a planet, while the nitrogen (N-14, N-15) isotope ratio can probably be used to date nitrogen-bearing Martian samples. The absorbance ratio of two adjacent lines of CO2 in the 2300/cm (4.3 micron) region of the spectrum was measured. The precision of the measurement is presently better than 1 percent and significant improvement is anticipated as rapid sweep-integration techniques and computer controlled data acquistion capabilities are incorporated.

  1. Time, Temporality, Now

    NASA Astrophysics Data System (ADS)

    Atmanspacher, Harald; Ruhnau, Eva

    The essays in this topical volume inquire into one of the most fundamental issues of philosophy and of the cognitive and natural sciences: the riddle of time. The central feature is the tension between the experience and the conceptualization of time, reflecting an apparently unavoidable antinomy of subjective first-person accounts and objective traditional science. Is time based in the physics of inanimate matter, or does it originate in the operation of our minds? Is it essential for the constitution of reality, or is it just an illusion? Issues of time, temporality, and nowness are paradigms for interdisciplinary work in many contemporary fields of research. The authors of this volume discuss profoundly the mutual relationships and inspiring perspectives. They address a general audience.

  2. Temporal Ventriloquism in a Purely Temporal Context

    ERIC Educational Resources Information Center

    Hartcher-O'Brien, Jessica; Alais, David

    2011-01-01

    This study examines how audiovisual signals are combined in time for a temporal analogue of the ventriloquist effect in a purely temporal context, that is, no spatial grounding of signals or other spatial facilitation. Observers were presented with two successive intervals, each defined by a 1250-ms tone, and indicated in which interval a brief…

  3. Overview and first results from project STABLE (STAble Boundary Layer Experiment)

    SciTech Connect

    Weber, A.H.; Kurzeja, R.J.

    1988-01-01

    The STABLE project (STAble Boundary Layer Experiment) is a multiyear research effort conceived in 1984 by the Savannah River Laboratory (SRL) and planned by several research groups to study turbulence and diffusion in the stable boundary layer (SBL). The program was jointly planned by Department of Energy (DOE) affiliated laboratories and universities including SRL, Atmospheric Turbulence and Diffusion Division (ATDD) of the National Oceanic and Atmospheric Administration (NOAA), Argonne National Laboratory (ANL), North Carolina State University (NCSU), and The Pennsylvania State University. STABLE's goals are to determine the spatial and temporal distribution of turbulent events during the nighttime, to determine the validity of present models and theories in describing the structure and evolution of the SBL, to determine the role of waves and intermittent turbulence in dispersing chemicals, and to determine better parameterization for describing the mean state and intermittent events in the SBL. By taking advantage of special facility, the program seeks to economize effort and cost. 1 ref., 7 figs.

  4. Automated annual cropland mapping using knowledge-based temporal features

    NASA Astrophysics Data System (ADS)

    Waldner, François; Canto, Guadalupe Sepulcre; Defourny, Pierre

    2015-12-01

    Global, timely, accurate and cost-effective cropland mapping is a prerequisite for reliable crop condition monitoring. This article presented a simple and comprehensive methodology capable to meet the requirements of operational cropland mapping by proposing (1) five knowledge-based temporal features that remain stable over time, (2) a cleaning method that discards misleading pixels from a baseline land cover map and (3) a classifier that delivers high accuracy cropland maps (> 80%). This was demonstrated over four contrasted agrosystems in Argentina, Belgium, China and Ukraine. It was found that the quality and accuracy of the baseline impact more the certainty of the classification rather than the classification output itself. In addition, it was shown that interpolation of the knowledge-based features increases the stability of the classifier allowing for its re-use from year to year without recalibration. Hence, the method shows potential for application at larger scale as well as for delivering cropland map in near real time.

  5. Temporal nonlocality in bistable perception

    NASA Astrophysics Data System (ADS)

    Atmanspacher, Harald; Filk, Thomas

    2012-12-01

    A novel conceptual framework for theoretical psychology is presented and illustrated for the example of bistable perception. A basic formal feature of this framework is the non-commutativity of operations acting on mental states. A corresponding model for the bistable perception of ambiguous stimuli, the Necker-Zeno model, is sketched and some empirical evidence for it so far is described. It is discussed how a temporal nonlocality of mental states, predicted by the model, can be understood and tested.

  6. Atlas of temporal variations - interdisciplinary scientific work

    NASA Astrophysics Data System (ADS)

    Gamburtsev, A. G.; Oleinik, O. V.

    2003-04-01

    The year 2002 will culminate in the publication of the third volume of the fundamental interdisciplinary work "Atlas of Temporal Variations in Natural, Anthropogenic and Social Processes", which now will comprise three volumes (1994, 1998, 2002). The Atlas has pooled the information on the main peculiarities of processes' behaviour in various natural and humanitarian spheres over the widest temporal and spatial range. The main scientific goal of the work consists in discovering the behaviour pattern of natural, anthropogenic and social processes and the cause and effect links between them. Thus, the Atlas contains extensive comparative generalisation from the vastly different data. For one thing, it is a fundamental work on the law-governed nature of evolution in natural and social spheres; for another, it can be used as a reference book and valuable source of information for research in different directions. The authors seek to treat every piece of information as part of an integrated whole. When analysing the data, we operate on the premise that surrounding nature, society and their elements are open dynamic systems. Systems of this kind exhibit non-linear characteristics and a tendency towards ordered and chaotic behaviour. These features are revealed in the course of the analysis of time series. The data processing procedures applied are unified, all processes being generally expressed in terms of their time series and time-spectral diagrams. The technique is aimed at determination of investigated parameters' rhythms and the analysis of their evolution. This approach enables us to show the dynamics of processes occurring in absolutely dissimilar objects and performs their comparative analysis, with particular emphasis placed on rhythms and trends. As a result successions of illustrations are obtained and formed the basis of the Atlas. The Atlas covers processes that occur in objects belonging to the lithosphere, atmosphere, hydrosphere and social sphere as well

  7. Stable coherent states

    NASA Astrophysics Data System (ADS)

    Zipfel, Antonia; Thiemann, Thomas

    2016-04-01

    We analyze the stability under time evolution of complexifier coherent states (CCS) in one-dimensional mechanical systems. A system of coherent states is called stable if it evolves into another coherent state. It turns out that a system can only possess stable CCS if the classical evolution of the variable z =e-i Lχ Cq for a given complexifier C depends only on z itself and not on its complex conjugate. This condition is very restrictive in general so that only a few systems exist that obey this condition. However, it is possible to access a wider class of models that in principle may allow for stable coherent states associated with certain regions in the phase space by introducing action-angle coordinates.

  8. Stable Imaging for Astronomy (SIA)

    NASA Astrophysics Data System (ADS)

    Beaulieu, Mathilde; Ottogalli, Sebastien; Preis, Olivier; Bresson, Yves; Rivet, Jean-Pierre; Abe, Lyu; Vakili, Farrokh

    2014-07-01

    One of the most challenging fields of astronomical instrumentation is probably high-contrast imaging since it ultimately combines ultra-high sensitivity at low flux and the ability to cope with photon flux contrasts of several hundreds of millions or even more. These two aspects implicitly require that high-contrast instruments should be highly stable in the sense of the reproducibility of their measurements at different times, but also, continuously stable over time. In most high contrast instruments or experiments, their sensitivity is broken after at most tens of minutes of operation due to uncontrolled and unknown behaviour of the whole experiment regarding the environmental conditions. In this paper, we introduce a general approach of an exhaustive stability study for high-contrast imaging that has been initiated at Lagrange Laboratory, Observatoire de la Côte d'Azur (OCA). On a practical ground, one of the fundamental issues of this study is the metrology, which is the basis of all reproducible measurements. We describe a small experiment designed to understand the behaviour of one of our ultra-precise metrology tools (a commercial sub-nanometric 3-way interferometer) and derive the conditions under which its operation delivers reliable results. The approach will apply to the high-contrast imaging test-bench SPEED, under development at OCA.

  9. The Stable Pairing Problem

    ERIC Educational Resources Information Center

    Greenwell, Raymond N.; Seabold, Daniel E.

    2014-01-01

    The Gale-Shapley stable marriage theorem is a fascinating piece of twentieth-century mathematics that has many practical applications--from labor markets to school admissions--yet is accessible to secondary school mathematics students. David Gale and Lloyd Shapley were both mathematicians and economists who published their work on the Stable…

  10. Stable isotope studies

    SciTech Connect

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  11. Entities on a Temporal Scale.

    PubMed

    Murray, Christopher M; Crother, Brian I

    2016-03-01

    Ontological understanding of biological units (i.e. what kinds of things are they) is crucial to their use in experimental design, analysis, and interpretation. Conceptualizing fundamental units in biology as individuals or classes is important for subsequent development of discovery operations. While the criteria for diagnosing individuals are acknowledged, temporal boundedness is often misinterpreted and temporal minima are applied to units in question. This results in misdiagnosis or abandonment of ontological interpretation altogether. Biological units such as areas of endemism in biogeography and species in evolutionary biology fall victim to such problems. Our goal here is to address the misconception that biological individuals such as species and areas of endemism have a temporal minimum. Areas of endemism can persist within small temporal boundaries in the context of metapopulation dynamics, island biogeography, and range expansion and contraction. Similarly, lineage reticulation illustrates examples of short-lived species. Here, examples of known entities are provided to illustrate their persistence on short time scales in attempt to rescue future interpretation of biological units from ontological misdiagnosis, elucidate the philosophical individuality of areas of endemism and species with short lifespans, and provide justification for the "snapshot in time" diagnostic approach. PMID:26342483

  12. Ultra-stable harmonically mode-locked erbium-doped waveguide laser

    NASA Astrophysics Data System (ADS)

    Fanto, M. L.; Erdmann, R. K.; Wysocki, B. T.; Malowicki, J. E.; McEwen, T. A.

    2007-04-01

    Generation of stable pulses and a frequency stabilized optical comb are two key requirements for Fourier Based Arbitrary Waveform Generation (AWG) techniques. The longitudinal mode spacing of the laser must remain as stable as possible to permit effective isolation and processing of the modes for waveform synthesis. The short and long term temporal stability ultimately limits the system's precision as well as its operability in fielded systems. A packaged erbium-doped waveguide provided a highly compact gain medium for the harmonically mode-locked laser design. Stability was achieved by use of an intracavity etalon for frequency stabilization of the optical comb, a Pound-Drever- Hall (PDH) method, and an active bias feedback loop for low frequency noise suppression. The temperature was controlled to limit cavity length variation, and the contribution to stability of each method is quantitatively assessed. The system's stable operating time was increased from hours to greater than a day, and the timing jitter is demonstrated to be lower than that of commercially available erbium-doped fiber laser (EDFL) systems. Applications to optical signal synthesis and Laser Radar are briefly discussed.

  13. Comprehensive Retrieval of Spatio-temporal Variations in Atmospheric Radionuclides just after the Fukushima Accident by Analyzing Filter-tapes of Operational Air Pollution Monitoring Stations in Eastern Japan

    NASA Astrophysics Data System (ADS)

    Tsuruta, Haruo; Oura, Yasuji; Ebihara, Mitsuru; Ohara, Toshimasa; Moriguchi, Yuichi; Nakajima, Teruyuki

    2016-04-01

    After the Fukushima Daiichi Nuclear Power Station (FD1NPS) accident on March 11, 2011, many datasets have been available of deposition density of radionuclides in soils in eastern Japan. By contrast, no time-series data of atmospheric radionuclides has been measured in the Fukushima prefecture (FP), although very limited data is available in the Tokyo metropolitan area (TMA) located more than 170 km southwest of the FD1NPS. As a result, atmospheric transport models simulating the atmospheric concentrations and surface deposition of radionuclides have large uncertainty, as well as the estimate of release rate of source terms and of internal exposure from inhalation. One year after the accident, we collected the used filter-tapes installed in Suspended Particulate Matter (SPM) monitors with beta-ray attenuation method operated by local governments in the air pollution monitoring network of eastern Japan. The SPM monitoring stations are mostly located in the urban and/or industrial area to measure the hourly mass concentration of SPM less than 10 μm in diameter for health effect due to atmospheric aerosols. By measuring radionuclides in SPM on the filter-tapes, we retrieved hourly atmospheric Cs-134 and Cs-137 concentrations during March 12-23, 2011, when atmospheric, aquatic, and terrestrial environments were seriously suffered in most of eastern Japan. Until now, we measured hourly radiocesium at around 100 SPM sites in the southern Tohoku region (ST) including the FP and in the TMA. By analysing the dataset, about 10 plumes/polluted air masses with Cs-137 concentrations higher than 10 Bq m-3 were found, and some plumes were newly detected in this study. And the spatio-temporal distributions of atmospheric Cs-137 were clearly shown for all the plumes. The east coast area of the FP where the FD1NPS was located in the centre was attacked several times by the plumes, and suffered the highest time-integrated Cs-137 concentration during the period among the ST and TMA

  14. Robust temporal alignment of multimodal cardiac sequences

    NASA Astrophysics Data System (ADS)

    Perissinotto, Andrea; Queirós, Sandro; Morais, Pedro; Baptista, Maria J.; Monaghan, Mark; Rodrigues, Nuno F.; D'hooge, Jan; Vilaça, João. L.; Barbosa, Daniel

    2015-03-01

    Given the dynamic nature of cardiac function, correct temporal alignment of pre-operative models and intraoperative images is crucial for augmented reality in cardiac image-guided interventions. As such, the current study focuses on the development of an image-based strategy for temporal alignment of multimodal cardiac imaging sequences, such as cine Magnetic Resonance Imaging (MRI) or 3D Ultrasound (US). First, we derive a robust, modality-independent signal from the image sequences, estimated by computing the normalized cross-correlation between each frame in the temporal sequence and the end-diastolic frame. This signal is a resembler for the left-ventricle (LV) volume curve over time, whose variation indicates different temporal landmarks of the cardiac cycle. We then perform the temporal alignment of these surrogate signals derived from MRI and US sequences of the same patient through Dynamic Time Warping (DTW), allowing to synchronize both sequences. The proposed framework was evaluated in 98 patients, which have undergone both 3D+t MRI and US scans. The end-systolic frame could be accurately estimated as the minimum of the image-derived surrogate signal, presenting a relative error of 1.6 +/- 1.9% and 4.0 +/- 4.2% for the MRI and US sequences, respectively, thus supporting its association with key temporal instants of the cardiac cycle. The use of DTW reduces the desynchronization of the cardiac events in MRI and US sequences, allowing to temporally align multimodal cardiac imaging sequences. Overall, a generic, fast and accurate method for temporal synchronization of MRI and US sequences of the same patient was introduced. This approach could be straightforwardly used for the correct temporal alignment of pre-operative MRI information and intra-operative US images.

  15. Operant Conditioning

    PubMed Central

    Staddon, J. E. R.; Cerutti, D. T.

    2005-01-01

    Operant behavior is behavior “controlled” by its consequences. In practice, operant conditioning is the study of reversible behavior maintained by reinforcement schedules. We review empirical studies and theoretical approaches to two large classes of operant behavior: interval timing and choice. We discuss cognitive versus behavioral approaches to timing, the “gap” experiment and its implications, proportional timing and Weber's law, temporal dynamics and linear waiting, and the problem of simple chain-interval schedules. We review the long history of research on operant choice: the matching law, its extensions and problems, concurrent chain schedules, and self-control. We point out how linear waiting may be involved in timing, choice, and reinforcement schedules generally. There are prospects for a unified approach to all these areas. PMID:12415075

  16. High-Order Entropy Stable Formulations for Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Fisher, Travis C.

    2013-01-01

    A systematic approach is presented for developing entropy stable (SS) formulations of any order for the Navier-Stokes equations. These SS formulations discretely conserve mass, momentum, energy and satisfy a mathematical entropy inequality. They are valid for smooth as well as discontinuous flows provided sufficient dissipation is added at shocks and discontinuities. Entropy stable formulations exist for all diagonal norm, summation-by-parts (SBP) operators, including all centered finite-difference operators, Legendre collocation finite-element operators, and certain finite-volume operators. Examples are presented using various entropy stable formulations that demonstrate the current state-of-the-art of these schemes.

  17. Stable isotopes in mineralogy

    USGS Publications Warehouse

    O'Neil, J.R.

    1977-01-01

    Stable isotope fractionations between minerals are functions of the fundamental vibrational frequencies of the minerals and therefore bear on several topics of mineralogical interest. Isotopic compositions of the elements H, C, O, Si, and S can now be determined routinely in almost any mineral. A summary has been made of both published and new results of laboratory investigations, analyses of natural materials, and theoretical considerations which bear on the importance of temperature, pressure, chemical composition and crystal structure to the isotopic properties of minerals. It is shown that stable isotope studies can sometimes provide evidence for elucidating details of crystal structure and can be a powerful tool for use in tracing the reaction paths of mineralogical reactions. ?? 1977 Springer-Verlag.

  18. Stable local oscillator module.

    SciTech Connect

    Brocato, Robert Wesley

    2007-11-01

    This report gives a description of the development of a Stable Local Oscillator (StaLO) multi-chip module (MCM). It is a follow-on report to SAND2006-6414, Stable Local Oscillator Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. This report describes the development of an MCM-based version of the complete StaLO, fabricated on an alumina thick film hybrid substrate.

  19. Handbook of stable strontium

    SciTech Connect

    Skoryna, S.C.

    1981-01-01

    This book presents information on the following topics: chemistry of strontium; biogeochemistry of strontium; uptake of stable strontium by plants and effects on plant growth; divalent cation-dependent deposits in paramecium; effects of strontium ion on the hydrolysis of ATP; stronium ions and membranes - screening versus binding at charged surfaces; mitochondrial granules in the liver of rats kept on stable strontium supplementation; divalent cations and regulation of cyclic nucleotides in nervous systems; strontium as the substitute for calcium in the excitation-contraction coupling of crayfish muscle fibers; hemodynamic effects of strontium in the dog; some mechanical characteristics of strontium-mediated contractions in heart muscle; effects of calcium, magnesium, and strontium on drug-receptor interactions; strontium and histamine secretion; and effects of strontium in human dental enamel.

  20. Stable Charged Cosmic Strings

    SciTech Connect

    Weigel, H.; Quandt, M.; Graham, N.

    2011-03-11

    We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius {approx_equal}10{sup -18} m. The vacuum remains stable in our model, because neutral strings are not energetically favored.

  1. Stable charged cosmic strings.

    PubMed

    Weigel, H; Quandt, M; Graham, N

    2011-03-11

    We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≈10(-18)  m. The vacuum remains stable in our model, because neutral strings are not energetically favored. PMID:21469786

  2. Temporal plus epilepsy is a major determinant of temporal lobe surgery failures.

    PubMed

    Barba, Carmen; Rheims, Sylvain; Minotti, Lorella; Guénot, Marc; Hoffmann, Dominique; Chabardès, Stephan; Isnard, Jean; Kahane, Philippe; Ryvlin, Philippe

    2016-02-01

    Reasons for failed temporal lobe epilepsy surgery remain unclear. Temporal plus epilepsy, characterized by a primary temporal lobe epileptogenic zone extending to neighboured regions, might account for a yet unknown proportion of these failures. In this study all patients from two epilepsy surgery programmes who fulfilled the following criteria were included: (i) operated from an anterior temporal lobectomy or disconnection between January 1990 and December 2001; (ii) magnetic resonance imaging normal or showing signs of hippocampal sclerosis; and (iii) postoperative follow-up ≥ 24 months for seizure-free patients. Patients were classified as suffering from unilateral temporal lobe epilepsy, bitemporal epilepsy or temporal plus epilepsy based on available presurgical data. Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom over time. Predictors of seizure recurrence were investigated using Cox proportional hazards model. Of 168 patients included, 108 (63.7%) underwent stereoelectroencephalography, 131 (78%) had hippocampal sclerosis, 149 suffered from unilateral temporal lobe epilepsy (88.7%), one from bitemporal epilepsy (0.6%) and 18 (10.7%) from temporal plus epilepsy. The probability of Engel class I outcome at 10 years of follow-up was 67.3% (95% CI: 63.4-71.2) for the entire cohort, 74.5% (95% CI: 70.6-78.4) for unilateral temporal lobe epilepsy, and 14.8% (95% CI: 5.9-23.7) for temporal plus epilepsy. Multivariate analyses demonstrated four predictors of seizure relapse: temporal plus epilepsy (P < 0.001), postoperative hippocampal remnant (P = 0.001), past history of traumatic or infectious brain insult (P = 0.022), and secondary generalized tonic-clonic seizures (P = 0.023). Risk of temporal lobe surgery failure was 5.06 (95% CI: 2.36-10.382) greater in patients with temporal plus epilepsy than in those with unilateral temporal lobe epilepsy. Temporal plus epilepsy represents a hitherto unrecognized prominent cause of

  3. STABLE ISOTOPES AS INDICATORS OF SOIL WATER DYNAMICS IN WATERSHEDS

    EPA Science Inventory

    Stream water quality and quantity depend on discharge rates of water and nutrients from soils. However, soil-water storage is very dynamic and strongly influenced by plants. We analyzed stable isotopes of oxygen and hydrogen to quantify spatial and temporal changes in evaporati...

  4. Thermally stable laminating resins

    NASA Technical Reports Server (NTRS)

    Jones, R. J.; Vaughan, R. W.; Burns, E. A.

    1972-01-01

    Improved thermally stable laminating resins were developed based on the addition-type pyrolytic polymerization. Detailed monomer and polymer synthesis and characterization studies identified formulations which facilitate press molding processing and autoclave fabrication of glass and graphite fiber reinforced composites. A specific resin formulation, termed P10P was utilized to prepare a Courtaulds HMS reinforced simulated airfoil demonstration part by an autoclave molding process.

  5. Forensic Stable Isotope Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  6. Implementation and Operational Research: CD4 Count Monitoring Frequency and Risk of CD4 Count Dropping Below 200 Cells Per Cubic Millimeter Among Stable HIV-Infected Patients in New York City, 2007–2013

    PubMed Central

    Xia, Qiang; Torian, Lucia V.; Irvine, Mary; Harriman, Graham; Sepkowitz, Kent A.; Shepard, Colin W.

    2016-01-01

    Introduction: The evidence has begun to mount for diminishing the frequency of CD4 count testing. To determine whether these observations were applicable to an urban US population, we used New York City (NYC) surveillance data to explore CD4 testing among stable patients in NYC, 2007–2013. Methods: We constructed a population-based retrospective open cohort analysis of NYC HIV surveillance data. HIV+ patients aged ≥13 years with stable viral suppression (≥1 viral load the previous year; all <400 copies per milliliter) and immune status (≥1 CD4 the previous year; all ≥200 cells per cubic millimeter) entered the cohort the following year beginning January 1, 2007. Each subsequent year, eligible patients not previously included entered the cohort on January 1. Outcomes were annual frequency of CD4 monitoring and probability of maintaining CD4 ≥200 cells per cubic millimeter. A multivariable Cox model identified factors associated with maintaining CD4 ≥200 cells per cubic millimeter. Results: During 1.9 years of observation (median), 62,039 patients entered the cohort. The mean annual number of CD4 measurements among stable patients was 2.8 and varied little by year or characteristic. Two years after entering, 93.4% and 97.8% of those with initial CD4 350–499 and CD4 ≥500 cells per cubic millimeter, respectively, maintained CD4 ≥200 cells per cubic millimeter. Compared to those with initial CD4 ≥500 cells per cubic millimeter, those with CD4 200–349 cells per cubic millimeter and CD4 350–499 cells per cubic millimeter were more likely to have a CD4 <200 cells per cubic millimeter, controlling for sex, race, age, HIV risk group, and diagnosis year. Conclusions: In a population-based US cohort with well-controlled HIV, the probability of maintaining CD4 ≥200 cells per cubic millimeter for ≥2 years was >90% among those with initial CD4 ≥350 cells per cubic millimeter, suggesting that limited CD4 monitoring in these patients is appropriate

  7. Dynamics of Dissipative Temporal Solitons

    NASA Astrophysics Data System (ADS)

    Peschel, U.; Michaelis, D.; Bakonyi, Z.; Onishchukov, G.; Lederer, F.

    nonlinear interaction of forward and backward propagating fields, where cavity (radiation) losses are compensated for by gain or an external holding beam. Cavity solitons have been observed in Fabry-Perot cavities and single mirror feedback setups (for an overview see [8]). In contrast, propagating dissipative solitons consist of forward-propagating fields only. Recently, the existence of both stable temporal [9] and spatial propagating dissipative solitons [10] was experimentally demonstrated. It is evident that the study of dissipative solitons is of great practical relevance, because most real optical systems are dissipative by nature.

  8. Temporal Organization in Prose

    ERIC Educational Resources Information Center

    Kulhavy, Raymond W.; And Others

    1977-01-01

    High school students read textual passages organized around a semantic, temporal, or random theme. Free recall, semantically, and temporally-cued tests measured recall. During free recall, the organized passages yielded greater recall. For the cued tests, more words were remembered when the passage organization matched the type of test cue.…

  9. Temporal Bisection in Children.

    ERIC Educational Resources Information Center

    Droit-Volet, Sylvie; Wearden, John H.

    2001-01-01

    Trained 3-, 5-, and 8-year-olds in temporal bisection task, with nonstandard comparison stimuli spaced linearly between short or long standard visual stimuli. Statistical analyses and results from different theoretical models of the data all suggested that temporal sensitivity was higher in the 8-year-olds than in younger groups, even when the…

  10. Quantitative phase microscopy: automated background leveling techniques and smart temporal phase unwrapping.

    PubMed

    Goldstein, Goldie; Creath, Katherine

    2015-06-01

    In order for time-dynamic quantitative phase microscopy to yield meaningful data to scientists, raw phase measurements must be converted to sequential time series that are consistently phase unwrapped with minimal residual background shape. Beyond the initial phase unwrapping, additional steps must be taken to convert the phase to time-meaningful data sequences. This consists of two major operations both outlined in this paper and shown to operate robustly on biological datasets. An automated background leveling procedure is introduced that consistently removes background shape and minimizes mean background phase value fluctuations. By creating a background phase value that is stable over time, the phase values of features of interest can be examined as a function of time to draw biologically meaningful conclusions. Residual differences between sequential frames of data can be present due to inconsistent phase unwrapping, causing localized regions to have phase values at similar object locations inconsistently changed by large values between frames, not corresponding to physical changes in the sample being observed. This is overcome by introducing a new method, referred to as smart temporal unwrapping that temporally unwraps and filters the phase data such that small motion between frames is accounted for and phase data are unwrapped consistently between frames. The combination of these methods results in the creation of phase data that is stable over time by minimizing errors introduced within the processing of the raw data. PMID:26192681

  11. Temporal Prediction in lieu of Periodic Stimulation

    PubMed Central

    Schroeder, Charles E.; Wyart, Valentin

    2016-01-01

    Predicting not only what will happen, but also when it will happen is extremely helpful for optimizing perception and action. Temporal predictions driven by periodic stimulation increase perceptual sensitivity and reduce response latencies. At the neurophysiological level, a single mechanism has been proposed to mediate this twofold behavioral improvement: the rhythmic entrainment of slow cortical oscillations to the stimulation rate. However, temporal regularities can occur in aperiodic contexts, suggesting that temporal predictions per se may be dissociable from entrainment to periodic sensory streams. We investigated this possibility in two behavioral experiments, asking human participants to detect near-threshold auditory tones embedded in streams whose temporal and spectral properties were manipulated. While our findings confirm that periodic stimulation reduces response latencies, in agreement with the hypothesis of a stimulus-driven entrainment of neural excitability, they further reveal that this motor facilitation can be dissociated from the enhancement of auditory sensitivity. Perceptual sensitivity improvement is unaffected by the nature of temporal regularities (periodic vs aperiodic), but contingent on the co-occurrence of a fulfilled spectral prediction. Altogether, the dissociation between predictability and periodicity demonstrates that distinct mechanisms flexibly and synergistically operate to facilitate perception and action. SIGNIFICANCE STATEMENT Temporal predictions are increasingly recognized as fundamental instruments for optimizing performance, enabling mammals to exploit regularities in the world. However, the notion of temporal predictions is often confounded with the idea of entrainment to periodic sensory inputs. At the behavioral level, it is also unclear whether perceptual sensitivity and reaction time improvements benefit the same way from temporal predictions and periodic stimulation. In two behavioral experiments on human

  12. Electrically actuatable temporal tristimulus-color device

    DOEpatents

    Koehler, Dale R.

    1992-01-01

    The electrically actuated light filter operates in a cyclical temporal mode to effect a tristimulus-color light analyzer. Construction is based on a Fabry-Perot interferometer comprised of a high-speed movable mirror pair and cyclically powered electrical actuators. When combined with a single vidicon tube or a monochrome solid state image sensor, a temporally operated tristimulus-color video camera is effected. A color-generated is accomplished when constructed with a companion light source and is a flicker-free colored-light source for transmission type display systems. Advantages of low cost and small physical size result from photolithographic batch-processing manufacturability.

  13. Stable predictive control horizons

    NASA Astrophysics Data System (ADS)

    Estrada, Raúl; Favela, Antonio; Raimondi, Angelo; Nevado, Antonio; Requena, Ricardo; Beltrán-Carbajal, Francisco

    2012-04-01

    The stability theory of predictive and adaptive predictive control for processes of linear and stable nature is based on the hypothesis of a physically realisable driving desired trajectory (DDT). The formal theoretical verification of this hypothesis is trivial for processes with a stable inverse, but it is not for processes with an unstable inverse. The extended strategy of predictive control was developed with the purpose of overcoming methodologically this stability problem and it has delivered excellent performance and stability in its industrial applications given a suitable choice of the prediction horizon. From a theoretical point of view, the existence of a prediction horizon capable of ensuring stability for processes with an unstable inverse was proven in the literature. However, no analytical solution has been found for the determination of the prediction horizon values which guarantee stability, in spite of the theoretical and practical interest of this matter. This article presents a new method able to determine the set of prediction horizon values which ensure stability under the extended predictive control strategy formulation and a particular performance criterion for the design of the DDT generically used in many industrial applications. The practical application of this method is illustrated by means of simulation examples.

  14. The Voronoi spatio-temporal data structure

    NASA Astrophysics Data System (ADS)

    Mioc, Darka

    2002-04-01

    Current GIS models cannot integrate the temporal dimension of spatial data easily. Indeed, current GISs do not support incremental (local) addition and deletion of spatial objects, and they can not support the temporal evolution of spatial data. Spatio-temporal facilities would be very useful in many GIS applications: harvesting and forest planning, cadastre, urban and regional planning, and emergency planning. The spatio-temporal model that can overcome these problems is based on a topological model---the Voronoi data structure. Voronoi diagrams are irregular tessellations of space, that adapt to spatial objects and therefore they are a synthesis of raster and vector spatial data models. The main advantage of the Voronoi data structure is its local and sequential map updates, which allows us to automatically record each event and performed map updates within the system. These map updates are executed through map construction commands that are composed of atomic actions (geometric algorithms for addition, deletion, and motion of spatial objects) on the dynamic Voronoi data structure. The formalization of map commands led to the development of a spatial language comprising a set of atomic operations or constructs on spatial primitives (points and lines), powerful enough to define the complex operations. This resulted in a new formal model for spatio-temporal change representation, where each update is uniquely characterized by the numbers of newly created and inactivated Voronoi regions. This is used for the extension of the model towards the hierarchical Voronoi data structure. In this model, spatio-temporal changes induced by map updates are preserved in a hierarchical data structure that combines events and corresponding changes in topology. This hierarchical Voronoi data structure has an implicit time ordering of events visible through changes in topology, and it is equivalent to an event structure that can support temporal data without precise temporal

  15. Strategies for Global Optimization of Temporal Preferences

    NASA Technical Reports Server (NTRS)

    Morris, Paul; Morris, Robert; Khatib, Lina; Ramakrishnan, Sailesh

    2004-01-01

    A temporal reasoning problem can often be naturally characterized as a collection of constraints with associated local preferences for times that make up the admissible values for those constraints. Globally preferred solutions to such problems emerge as a result of well-defined operations that compose and order temporal assignments. The overall objective of this work is a characterization of different notions of global preference, and to identify tractable sub-classes of temporal reasoning problems incorporating these notions. This paper extends previous results by refining the class of useful notions of global temporal preference that are associated with problems that admit of tractable solution techniques. This paper also answers the hitherto open question of whether problems that seek solutions that are globally preferred from a Utilitarian criterion for global preference can be found tractably.

  16. Marginally Stable Nuclear Burning

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; Altamirano, D.

    2012-01-01

    Thermonuclear X-ray bursts result from unstable nuclear burning of the material accreted on neutron stars in some low mass X-ray binaries (LMXBs). Theory predicts that close to the boundary of stability oscillatory burning can occur. This marginally stable regime has so far been identified in only a small number of sources. We present Rossi X-ray Timing Explorer (RXTE) observations of the bursting, high- inclination LMXB 4U 1323-619 that reveal for the first time in this source the signature of marginally stable burning. The source was observed during two successive RXTE orbits for approximately 5 ksec beginning at 10:14:01 UTC on March 28, 2011. Significant mHz quasi- periodic oscillations (QPO) at a frequency of 8.1 mHz are detected for approximately 1600 s from the beginning of the observation until the occurrence of a thermonuclear X-ray burst at 10:42:22 UTC. The mHz oscillations are not detected following the X-ray burst. The average fractional rms amplitude of the mHz QPOs is 6.4% (3 - 20 keV), and the amplitude increases to about 8% below 10 keV.This phenomenology is strikingly similar to that seen in the LMXB 4U 1636-53. Indeed, the frequency of the mHz QPOs in 4U 1323-619 prior to the X-ray burst is very similar to the transition frequency between mHz QPO and bursts found in 4U 1636-53 by Altamirano et al. (2008). These results strongly suggest that the observed QPOs in 4U 1323-619 are, like those in 4U 1636-53, due to marginally stable nuclear burning. We also explore the dependence of the energy spectrum on the oscillation phase, and we place the present observations within the context of the spectral evolution of the accretion-powered flux from the source.

  17. Option Pricing with Log-stable Lévy Processes

    NASA Astrophysics Data System (ADS)

    Repetowicz, Przemysław; Richmond, Peter

    We model the logarithm of the price (log-price) of a financial asset as a random variable obtained by projecting an operator stable random vector with a scaling index matrix \\underline{\\underline E} onto a non-random vector. The scaling index \\underline{\\underline E} models prices of the individual financial assets (stocks, mutual funds, etc.). We find the functional form of the characteristic function of real powers of the price returns and we compute the expectation value of these real powers and we speculate on the utility of these results for statistical inference. Finally we consider a portfolio composed of an asset and an option on that asset. We derive the characteristic function of the deviation of the portfolio, mathfrak{D}_t^{(mathfrak{t})} , defined as a temporal change of the portfolio diminished by the the compound interest earned. We derive pseudo-differential equations for the option as a function of the log-stock-price and time and we find exact closed-form solutions to that equation. These results were not known before. Finally we discuss how our solutions correspond to other approximate results known from literature,in particular to the well known Black & Scholes equation.

  18. Stable local oscillator microcircuit.

    SciTech Connect

    Brocato, Robert Wesley

    2006-10-01

    This report gives a description of the development of a Stable Local Oscillator (StaLO) Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. The StaLO uses a comb generator followed by surface acoustic wave (SAW) filters. The comb generator creates a set of harmonic components of the 100MHz input signal. The SAW filters are narrow bandpass filters that are used to select the desired component and reject all others. The resulting circuit has very low sideband power levels and low phase noise (both less than -40dBc) that is limited primarily by the phase noise level of the input signal.

  19. Stable magnetic universes revisited

    NASA Astrophysics Data System (ADS)

    Tahamtan, T.; Halilsoy, M.

    2013-01-01

    Recent discovery of magnetars ( B˜1015 G) motivates us to consider magnetic universes in general relativity a new. A regular class of static, cylindrically symmetric pure magnetic field metrics is rederived in a different metric ansatz in all dimensions. Radial, time dependent perturbations show that for dimensions d>3 such spacetimes are stable at both near r≈0 and large radius r→∞. For d=3, however, simultaneous stability requirement at both, near and far radial distances can not be reconciled for time-dependent perturbations. We argue that this distinct property may be the cause for the absence of pure magnetic black holes in d=3. Restricted, numerical geodesics for neutral particles reveal a gravitational confinement around the center in the polar plane. Charged, time-like geodesics for d=4 are shown numerically to remain confined as well.

  20. Economic Impact of Stable Flies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A dynamic model was created to estimate the economic impact of stable flies on livestock production. Based upon a nationwide average of 10 stable flies per animal for 3 months per year, the model estimates the impact of stable flies to be $543 million to the dairy industry, $1.34 billion to pasture ...

  1. Bi-stable optical actuator

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2000-01-01

    The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

  2. Managing temporal relations

    NASA Technical Reports Server (NTRS)

    Britt, Daniel L.; Geoffroy, Amy L.; Gohring, John R.

    1990-01-01

    Various temporal constraints on the execution of activities are described, and their representation in the scheduling system MAESTRO is discussed. Initial examples are presented using a sample activity described. Those examples are expanded to include a second activity, and the types of temporal constraints that can obtain between two activities are explored. Soft constraints, or preferences, in activity placement are discussed. Multiple performances of activities are considered, with respect to both hard and soft constraints. The primary methods used in MAESTRO to handle temporal constraints are described as are certain aspects of contingency handling with respect to temporal constraints. A discussion of the overall approach, with indications of future directions for this research, concludes the study.

  3. Stable umbral chromospheric structures

    NASA Astrophysics Data System (ADS)

    Henriques, V. M. J.; Scullion, E.; Mathioudakis, M.; Kiselman, D.; Gallagher, P. T.; Keenan, F. P.

    2015-02-01

    Aims: We seek to understand the morphology of the chromosphere in sunspot umbra. We investigate if the horizontal structures observed in the spectral core of the Ca II H line are ephemeral visuals caused by the shock dynamics of more stable structures, and examine their relationship with observables in the H-alpha line. Methods: Filtergrams in the core of the Ca II H and H-alpha lines as observed with the Swedish 1-m Solar Telescope are employed. We utilise a technique that creates composite images and tracks the flash propagation horizontally. Results: We find 0.̋15 wide horizontal structures, in all of the three target sunspots, for every flash where the seeing is moderate to good. Discrete dark structures are identified that are stable for at least two umbral flashes, as well as systems of structures that live for up to 24 min. We find cases of extremely extended structures with similar stability, with one such structure showing an extent of 5''. Some of these structures have a correspondence in H-alpha, but we were unable to find a one-to-one correspondence for every occurrence. If the dark streaks are formed at the same heights as umbral flashes, there are systems of structures with strong departures from the vertical for all three analysed sunspots. Conclusions: Long-lived Ca II H filamentary horizontal structures are a common and likely ever-present feature in the umbra of sunspots. If the magnetic field in the chromosphere of the umbra is indeed aligned with the structures, then the present theoretical understanding of the typical umbra needs to be revisited. Movies associated to Figs. 3 and 4 are available in electronic form at http://www.aanda.org

  4. Stable superstring relics

    SciTech Connect

    Chang, S.; Coriano, C.; Faraggi, A.E. |

    1996-05-15

    The authors investigate the cosmological constraints on exotic stable matter states which arise in realistic free fermionic superstring models. These states appear in the superstring models due to a ``Wilson-line`` breaking of the unifying non-Abelian gauge symmetry. In the models that they consider the unifying SO(10) gauge symmetry is broken at the string level to SO(6) x SO(4), SU(5) x U(1) or SU(3) x SU(2) x U(1). The exotic matter states are classified according to the patterns of the SO(10) symmetry breaking. In SO(6) x XO(4) and SU(5) x U(1) type models one obtains fractionally charged states with Q{sub e.m.} = {+-}1/2. In SU(3) x SU(2) x U(1) type models one also obtains states with the regular charges under the Standard Model gauge group but with ``fractional`` charges under the U(1){sub z{prime}} symmetry. These states include down-like color triplets and electroweak doublets, as well as states which are Standard Model singlets. By analyzing the renormalizable and nonrenormalizable terms of the superpotential in a specific superstring model, the authors show that these exotic states can be stable. They investigate the cosmological constraints on the masses and relic density of the exotic states. They propose that, while the abundance and the masses of the fractionally charged states are highly constrained, the Standard Model-like states, and in particular the Standard Model singlet, are good dark matter candidates.

  5. Temperature Compensated Sapphire Resonator for Ultra-Stable Oscillator Capability

    NASA Technical Reports Server (NTRS)

    Dick, G. J.; Santiago, D. G.; Wang, R. T.

    1994-01-01

    We report on the design and test of a whispering gallery sapphire resonator for which the dominant microwave mode family shows frequency-stable, compensated operation for temperatures above 77 kelvin.

  6. Stable face representations

    PubMed Central

    Jenkins, Rob; Burton, A. Mike

    2011-01-01

    Photographs are often used to establish the identity of an individual or to verify that they are who they claim to be. Yet, recent research shows that it is surprisingly difficult to match a photo to a face. Neither humans nor machines can perform this task reliably. Although human perceivers are good at matching familiar faces, performance with unfamiliar faces is strikingly poor. The situation is no better for automatic face recognition systems. In practical settings, automatic systems have been consistently disappointing. In this review, we suggest that failure to distinguish between familiar and unfamiliar face processing has led to unrealistic expectations about face identification in applied settings. We also argue that a photograph is not necessarily a reliable indicator of facial appearance, and develop our proposal that summary statistics can provide more stable face representations. In particular, we show that image averaging stabilizes facial appearance by diluting aspects of the image that vary between snapshots of the same person. We review evidence that the resulting images can outperform photographs in both behavioural experiments and computer simulations, and outline promising directions for future research. PMID:21536553

  7. Unusually stable liquid foams.

    PubMed

    Rio, Emmanuelle; Drenckhan, Wiebke; Salonen, Anniina; Langevin, Dominique

    2014-03-01

    Obtaining stable liquid foams is an important issue in view of their numerous applications. In some of these, the liquid foam in itself is of interest, in others, the liquid foam acts as a precursor for the generation of solid foam. In this short review, we will make a survey of the existing results in the area. This will include foams stabilised by surfactants, proteins and particles. The origin of the stability is related to the slowing down of coarsening, drainage or coalescence, and eventually to their arrest. The three effects are frequently coupled and in many cases, they act simultaneously and enhance one another. Drainage can be arrested if the liquid of the foam either gels or solidifies. Coalescence is slowed down by gelified foam films, and it can be arrested if the films become very thick and/or rigid. These mechanisms are thus qualitatively easy to identify, but they are less easy to model in order to obtain quantitative predictions. The slowing down of coarsening requests either very thick or small films, and its arrest was observed in cases where the surface compression modulus was large. The detail of the mechanisms at play remains unclear. PMID:24342735

  8. Effects of extracellular calcium and of the calcium entry blockers flunarizine and nimodipine on contractile responses in human temporal arteries.

    PubMed

    Jansen, I; Edvinsson, L

    1986-12-01

    Contraction induced by 124 mM potassium followed the depolarization of smooth-muscle cells and activation of potential-operated calcium channels in human temporal arteries. The contraction elicited consisted of two phases, one rapid and one slowly developing stable phase; both were affected by the two calcium entry blockers flunarizine and nimodipine but at significantly different concentrations. In calcium-free medium 124 mM potassium resulted in a weak contraction. Addition of calcium caused a concentration-dependent contraction that was attenuated by the calcium entry blockers at concentrations comparable to those inhibiting the second phase. The results suggested that in human temporal arteries flunarizine and nimodipine act as calcium entry blockers; there was good correlation with the therapeutic plasma concentration for nimodipine but not for flunarizine. PMID:3802190

  9. Stable electroosmotically driven actuators

    NASA Astrophysics Data System (ADS)

    Sritharan, Deepa; Motsebo, Mylene; Tumbic, Julia; Smela, Elisabeth

    2013-04-01

    We have previously presented "nastic" actuators based on electroosmotic (EO) pumping of fluid in microchannels using high electric fields for potential application in soft robotics. In this work we address two challenges facing this technology: applying EO to meso-scale devices and the stability of the pumping fluid. The hydraulic pressure achieved by EO increases with as 1/d2, where d is the depth of the microchannel, but the flow rate (which determines the stroke and the speed) is proportional to nd, where n is the number of channels. Therefore to get high force and high stroke the device requires a large number of narrow channels, which is not readily achievable using standard microfabrication techniques. Furthermore, for soft robotics the structure must be soft. In this work we present a method of fabricating a three-dimensional porous elastomer to serve as the array of channels based on a sacrificial sugar scaffold. We demonstrate the concept by fabricating small pumps. The flexible devices were made from polydimethylsiloxane (PDMS) and comprise the 3D porous elastomer flanked on either side by reservoirs containing electrodes. The second issue addressed here involves the pumping fluid. Typically, water is used for EO, but water undergoes electrolysis even at low voltages. Since EO takes place at kV, these systems must be open to release the gases. We have recently reported that propylene carbonate (PC) is pumped at a comparable rate as water and is also stable for over 30 min at 8 kV. Here we show that PC is, however, degraded by moisture, so future EO systems must prevent water from reaching the PC.

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

    SciTech Connect

    Bornholdt, S.; Graudenz, D.

    1993-07-01

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

  11. Relative Priming of Temporal Local-Global Levels in Auditory Hierarchical Stimuli

    PubMed Central

    List, Alexandra; Justus, Timothy

    2009-01-01

    Priming is a useful tool for ascertaining the circumstances under which previous experiences influence behavior. Previously, using hierarchical stimuli, we demonstrated that selectively attending to one temporal scale of an auditory stimulus improved subsequent attention to a repeated (vs. changed) temporal scale, i.e., we demonstrated inter-trial auditory temporal level-priming. Here, we have extended those results to address whether level-priming relied on absolute or relative temporal information. Both relative and absolute temporal information are important in auditory perception: speech and music can be recognized over various temporal scales, but become uninterpretable to a listener when presented too quickly or slowly. We first confirmed that temporal level-priming generalized over new temporal scales. Second, in the context of multiple temporal scales, we found that temporal level-priming operates predominantly on the basis of relative, rather than absolute, temporal information. These findings are discussed in the context of expectancies and relational invariance in audition. PMID:20045889

  12. Temporal Moments in Hydrogeophysics

    NASA Astrophysics Data System (ADS)

    Pollock, D.; Cirpka, O. A.

    2007-12-01

    Electrical Resistivity Tomography (ERT) has been tested as monitoring tool for salt-tracer experiments by various authors. So far, the analysis of such experiments has been done by a two-step procedure [Kemna et al., 2002; Vanderborght et al., 2005; Singha and Gorelick, 2005]. In the first step, classical geophysical inversion methods have been used to infer the distribution of electrical conductivity, which is transferred to an estimated concentration distribution of the tracer. Subsequently, the inferred concentration images were analyzed to estimate hydraulic quantities such as the velocity distribution. This approach has two disadvantages: The concentration distribution is reconstructed with a high spatial resolution, but the estimate is uncertain, and the estimation uncertainty is spatially correlated. These correlated uncertainties should be accounted for in the estimation of hydraulic conductivity from concentration values. The latter, unfortunately, is not practical because the reconstructed data sets are very large. The geophysical inversion is not enforced to be in agreement with basic hydromechanical constraints. E.g., Singha and Gorelick [2005] observed an apparent loss of solute mass when using ERT as monitoring tool. We propose considering the temporal moments of potential-difference time series. These temporal moments depend on temporal moments of concentration, which have already been used in the inference of hydraulic- conductivity distributions (Cirpka and Kitanidis, 2000). In our contribution, we present the complete set of equations leading from hydraulic conductivity via hydraulic heads, velocities, temporal moments of concentrations to temporal moments of potential differences for given flow and transport boundary conditions and electrode configurations. We also present how the sensitivity of temporal moments of potential differences on the hydraulic conductivity field can be computed without the need of storing intermediate sensitivities

  13. Functional rigidity of a methane biofilter during the temporal microbial succession.

    PubMed

    Kim, Tae Gwan; Jeong, So-Yeon; Cho, Kyung-Suk

    2014-04-01

    Temporal microbial succession was investigated in relation to the performance of a methane biofilter. A laboratory-scale biofilter packed with perlite was operated for 108 days, without a deliberate biomass control. The system performance was stable over the period with a mean elimination capacity of 1,563 g m(-3) day(-1), despite a temporal deterioration (45-56 days). Ribosomal-tag pyrosequencing showed that bacterial communities at days 14-28 were distinct from those of days 68-108. The accumulation of nonviable substances strongly coincided with the community change (R (2) > 0.97). Rhodobacter, Hydrogenophaga, and Methylomonas were dominated in the earlier period, while Methylocaldum and Methylococcus were abundant in the later period. The methanotrophic proportion gradually increased to 41 %, and type I methanotrophs became predominant over time. However, community structure and methanotrophic population density stably retained over time, allowing the system to keep the similar performance. Therefore, the perlite biofilter system was functionally rigid against the temporal microbial succession. PMID:24287932

  14. Nonclassicality of Temporal Correlations.

    PubMed

    Brierley, Stephen; Kosowski, Adrian; Markiewicz, Marcin; Paterek, Tomasz; Przysiężna, Anna

    2015-09-18

    The results of spacelike separated measurements are independent of distant measurement settings, a property one might call two-way no-signaling. In contrast, timelike separated measurements are only one-way no-signaling since the past is independent of the future but not vice versa. For this reason some temporal correlations that are formally identical to nonclassical spatial correlations can still be modeled classically. We propose a new formulation of Bell's theorem for temporal correlations; namely, we define nonclassical temporal correlations as the ones which cannot be simulated by propagating in time the classical information content of a quantum system given by the Holevo bound. We first show that temporal correlations between results of any projective quantum measurements on a qubit can be simulated classically. Then we present a sequence of general measurements on a single m-level quantum system that cannot be explained by propagating in time an m-level classical system and using classical computers with unlimited memory. PMID:26430975

  15. Temporal Aperture Modulation

    NASA Technical Reports Server (NTRS)

    Proctor, R. J.

    1981-01-01

    The two types of modulation techniques useful to X-ray imaging are reviewed. The use of optimum coded temporal aperature modulation is shown, in certain cases, to offer an advantage over a spatial aperture modulator. Example applications of a diffuse anisotropic X-ray background experiment and a wide field of view hard X-ray imager are discussed.

  16. Pediatric temporal bone rhabdomyosarcoma.

    PubMed

    Goldberg, Monica J

    2016-08-01

    Rhabdomyosarcoma is one of the most common soft-tissue sarcomas in children. Prompt diagnosis and treatment significantly improve survival; however, misdiagnosis is common because of this aggressive temporal bone lesion's similarity to more common benign diseases. Clinicians should maintain a high index of suspicion for rhabdomyosarcoma in patients with a presumed otologic infection not responsive to medical therapy. PMID:27467294

  17. Stable isotopes in leaf water of terrestrial plants.

    PubMed

    Cernusak, Lucas A; Barbour, Margaret M; Arndt, Stefan K; Cheesman, Alexander W; English, Nathan B; Feild, Taylor S; Helliker, Brent R; Holloway-Phillips, Meisha M; Holtum, Joseph A M; Kahmen, Ansgar; McInerney, Francesca A; Munksgaard, Niels C; Simonin, Kevin A; Song, Xin; Stuart-Williams, Hilary; West, Jason B; Farquhar, Graham D

    2016-05-01

    Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water. PMID:26715126

  18. Spatial and temporal variations of microbial community in a mixed plug-flow loop reactor fed with dairy manure

    PubMed Central

    Li, Yueh-Fen; Chen, Po-Hsu; Yu, Zhongtang

    2014-01-01

    Mixed plug-flow loop reactor (MPFLR) has been widely adopted by the US dairy farms to convert cattle manure to biogas. However, the microbiome in MPFLR digesters remains unexplored. In this study, the microbiome in a MPFLR digester operated on a mega-dairy farm was examined thrice over a 2 month period. Within 23 days of retention time, 55–70% of total manure solid was digested. Except for a few minor volatile fatty acids (VFAs), total VFA concentration and pH remained similar along the course of the digester and over time. Metagenomic analysis showed that although with some temporal variations, the bacterial community was rather stable spatially in the digester. The methanogenic community was also stable both spatially and temporally in the digester. Among methanogens, genus Methanosaeta dominated in the digester. Quantitative polymerase chain reaction (qPCR) analysis and metagenomic analysis yielded different relative abundance of individual genera of methanogens, especially for Methanobacterium, which was predominant based on qPCR analysis but undetectable by metagenomics. Collectively, the results showed that only small microbial and chemical gradients existed within the digester, and the digestion process occurred similarly throughout the MPFLR digester. The findings of this study may help improve the operation and design of this type of manure digesters. PMID:24690147

  19. Delayed Reinforcement of Operant Behavior

    ERIC Educational Resources Information Center

    Lattal, Kennon A.

    2010-01-01

    The experimental analysis of delay of reinforcement is considered from the perspective of three questions that seem basic not only to understanding delay of reinforcement but also, by implication, the contributions of temporal relations between events to operant behavior. The first question is whether effects of the temporal relation between…

  20. High-order entropy stable finite difference schemes for nonlinear conservation laws: Finite domains

    NASA Astrophysics Data System (ADS)

    Fisher, Travis C.; Carpenter, Mark H.

    2013-11-01

    Nonlinear entropy stability is used to derive provably stable high-order finite difference operators including boundary closure stencils, for the compressible Navier-Stokes equations. A comparison technique is used to derive a new Entropy Stable Weighted Essentially Non-Oscillatory (SSWENO) finite difference method, appropriate for simulations of problems with shocks. Viscous terms are approximated using conservative, entropy stable, narrow-stencil finite difference operators. The efficacy of the new discrete operators is demonstrated using both smooth and discontinuous test cases.

  1. Compact and stable multibeam fiber injector

    SciTech Connect

    Collins, L. F., LLNL

    1998-07-01

    A compact and stable 20-beam injector was built for launching laser light into fibers for Fabry Perot velocity measurements of shock-driven surfaces. The fiber injector uses commercial mounts on mini-rails. Dielectric-coated beamsplitters provide accurate amplitude division. Minimal adjustments for stable operation are permitted by the use of a real-time video-viewer. The video system includes a non-linear camera for CW alignment and a linearized camera with a frame grabber for pulsed measurement and analysis. All 20-injection points are displayed on a single monitor. Optical requirements are given for image relay and magnification. Stimulated Brillouin scattering limitations on high-power are quantified.

  2. Multisensory temporal integration: Task and stimulus dependencies

    PubMed Central

    Stevenson, Ryan A.; Wallace, Mark T.

    2013-01-01

    The ability of human sensory systems to integrate information across the different modalities provides a wide range of behavioral and perceptual benefits. This integration process is dependent upon the temporal relationship of the different sensory signals, with stimuli occurring close together in time typically resulting in the largest behavior changes. The range of temporal intervals over which such benefits are seen is typically referred to as the temporal binding window (TBW). Given the importance of temporal factors in multisensory integration under both normal and atypical circumstances such as autism and dyslexia, the TBW has been measured with a variety of experimental protocols that differ according to criterion, task, and stimulus type, making comparisons across experiments difficult. In the current study we attempt to elucidate the role that these various factors play in the measurement of this important construct. The results show a strong effect of stimulus type, with the TBW assessed with speech stimuli being both larger and more symmetrical than that seen using simple and complex non-speech stimuli. These effects are robust across task and statistical criteria, and are highly consistent within individuals, suggesting substantial overlap in the neural and cognitive operations that govern multisensory temporal processes. PMID:23604624

  3. Temporal Prediction in lieu of Periodic Stimulation.

    PubMed

    Morillon, Benjamin; Schroeder, Charles E; Wyart, Valentin; Arnal, Luc H

    2016-02-24

    Predicting not only what will happen, but also when it will happen is extremely helpful for optimizing perception and action. Temporal predictions driven by periodic stimulation increase perceptual sensitivity and reduce response latencies. At the neurophysiological level, a single mechanism has been proposed to mediate this twofold behavioral improvement: the rhythmic entrainment of slow cortical oscillations to the stimulation rate. However, temporal regularities can occur in aperiodic contexts, suggesting that temporal predictions per se may be dissociable from entrainment to periodic sensory streams. We investigated this possibility in two behavioral experiments, asking human participants to detect near-threshold auditory tones embedded in streams whose temporal and spectral properties were manipulated. While our findings confirm that periodic stimulation reduces response latencies, in agreement with the hypothesis of a stimulus-driven entrainment of neural excitability, they further reveal that this motor facilitation can be dissociated from the enhancement of auditory sensitivity. Perceptual sensitivity improvement is unaffected by the nature of temporal regularities (periodic vs aperiodic), but contingent on the co-occurrence of a fulfilled spectral prediction. Altogether, the dissociation between predictability and periodicity demonstrates that distinct mechanisms flexibly and synergistically operate to facilitate perception and action. PMID:26911682

  4. Stable and sporadic symbiotic communities of coral and algal holobionts.

    PubMed

    Hester, Eric R; Barott, Katie L; Nulton, Jim; Vermeij, Mark Ja; Rohwer, Forest L

    2016-05-01

    Coral and algal holobionts are assemblages of macroorganisms and microorganisms, including viruses, Bacteria, Archaea, protists and fungi. Despite a decade of research, it remains unclear whether these associations are spatial-temporally stable or species-specific. We hypothesized that conflicting interpretations of the data arise from high noise associated with sporadic microbial symbionts overwhelming signatures of stable holobiont members. To test this hypothesis, the bacterial communities associated with three coral species (Acropora rosaria, Acropora hyacinthus and Porites lutea) and two algal guilds (crustose coralline algae and turf algae) from 131 samples were analyzed using a novel statistical approach termed the Abundance-Ubiquity (AU) test. The AU test determines whether a given bacterial species would be present given additional sampling effort (that is, stable) versus those species that are sporadically associated with a sample. Using the AU test, we show that coral and algal holobionts have a high-diversity group of stable symbionts. Stable symbionts are not exclusive to one species of coral or algae. No single bacterial species was ubiquitously associated with one host, showing that there is not strict heredity of the microbiome. In addition to the stable symbionts, there was a low-diversity community of sporadic symbionts whose abundance varied widely across individual holobionts of the same species. Identification of these two symbiont communities supports the holobiont model and calls into question the hologenome theory of evolution. PMID:26555246

  5. Identifying pre-Historic Land use Through Stable Isotope and Geomorphic Analyses

    NASA Astrophysics Data System (ADS)

    White, D. M.; Springer, G. S.; Rowe, H. D.

    2006-12-01

    The effects of prehistoric and modern land use may be recorded in cave stalagmites and clastic sediments as variations in δ13C, which describe the relative influence of C3 versus C4 plants. Mass spectrometry of macerated organic material in the cave sediments display fluctuations in δ13C representing changes in floral composition at the time of deposition. We report unexplained stable isotope excursions (δ13C) in stalagmites of a West Virginia cave that are temporally associated (~ 1850 BP) with Native American presence in the study area. We use spatially explicit, but geographically separated datasets of δ13C in clastic cave sediments to distinguish between pre-European anthropogenic effects, chemical disequilibria, or alternate terrestrial explanations for spatially explicit variations of δ13C. We use a new technique whereby known, independent climate-driven δ13C timelines are subtracted from histories suspected of containing land use signals to uncover anomalies perhaps attributable to prehistoric land use. Hydrologic and geomorphic responses are represented by changes in sediment characteristics and subtle grain size variations. The residual anomalies represent pre-European land use or undiscovered terrestrial processes operating within the watershed. Studies of spatial and temporal variations of δ13C provide an important new tool for our understanding of interactions between humans and ecosystems. Correlating prehistoric land use with subsequent recovery offers the rare opportunity to project ecosystem recovery from modern disturbances.

  6. Coverage centralities for temporal networks*

    NASA Astrophysics Data System (ADS)

    Takaguchi, Taro; Yano, Yosuke; Yoshida, Yuichi

    2016-02-01

    Structure of real networked systems, such as social relationship, can be modeled as temporal networks in which each edge appears only at the prescribed time. Understanding the structure of temporal networks requires quantifying the importance of a temporal vertex, which is a pair of vertex index and time. In this paper, we define two centrality measures of a temporal vertex based on the fastest temporal paths which use the temporal vertex. The definition is free from parameters and robust against the change in time scale on which we focus. In addition, we can efficiently compute these centrality values for all temporal vertices. Using the two centrality measures, we reveal that distributions of these centrality values of real-world temporal networks are heterogeneous. For various datasets, we also demonstrate that a majority of the highly central temporal vertices are located within a narrow time window around a particular time. In other words, there is a bottleneck time at which most information sent in the temporal network passes through a small number of temporal vertices, which suggests an important role of these temporal vertices in spreading phenomena. Contribution to the Topical Issue "Temporal Network Theory and Applications", edited by Petter Holme.Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjb/e2016-60498-7

  7. Audiotactile temporal order judgments.

    PubMed

    Zampini, Massimiliano; Brown, Timothy; Shore, David I; Maravita, Angelo; Röder, Brigitte; Spence, Charles

    2005-03-01

    We report a series of three experiments in which participants made unspeeded 'Which modality came first?' temporal order judgments (TOJs) to pairs of auditory and tactile stimuli presented at varying stimulus onset asynchronies (SOAs) using the method of constant stimuli. The stimuli were presented from either the same or different locations in order to explore the potential effect of redundant spatial information on audiotactile temporal perception. In Experiment 1, the auditory and tactile stimuli had to be separated by nearly 80 ms for inexperienced participants to be able to judge their temporal order accurately (i.e., for the just noticeable difference (JND) to be achieved), no matter whether the stimuli were presented from the same or different spatial positions. More experienced psychophysical observers (Experiment 2) also failed to show any effect of relative spatial position on audiotactile TOJ performance, despite having much lower JNDs (40 ms) overall. A similar pattern of results was found in Experiment 3 when silent electrocutaneous stimulation was used rather than vibrotactile stimulation. Thus, relative spatial position seems to be a less important factor in determining performance for audiotactile TOJ than for other modality pairings (e.g., audiovisual and visuotactile). PMID:15698825

  8. Temporal stability of chemical hormesis (CH): Is CH just a temporary stop on the road to thresholds and toxic responses?

    PubMed

    Mushak, Paul

    2016-11-01

    Chemical hormesis (CH) is currently described as a nonmonotonic, bidirectional dose-response relationship for chemicals, where a stimulatory, (beneficial?) response at low dose or exposure is followed by an inhibitory response at higher doses/exposures (or vice-versa). CH is depicted as U(J)-shaped or inverse U(J)-shaped curves, i.e., curve slopes change sign. Some describe CH as a homeostasis-preserving response; others view CH as adaptive or (pre)conditioning responses to chemical stress. One aspect of CH and stress hormesis in general that has not been researched is its temporal stability, i.e., persistence, particularly in experimental animals and humans having long-term chemical stressing. Once maximized, does the CH response remain operative over the entire time of chemical exposure? One possible reason for the question's neglect is that temporal stability, e.g., 'steady-state hormesis,' has been assumed. Another is that CH temporality is not well understood or has been under-appreciated as to its importance. Available data, mainly for simpler biological systems, describe cases of transitory CH. Other examples, in human and experimental animal studies, show transitory existence of CH and, in some specialized cases, persisting CH. Also, certain disease state-induced hormetic responses are transitory over time in humans. The question requires resolution if CH is to be considered (i) a stable and beneficial or adverse response, (ii) a stable dose-response model competitive with stable threshold and linear, nonthreshold (LNT) dose-response models, and (iii) a model having any impact on, or role in, regulatory and public health policies. PMID:27396315

  9. Earthquakes in Stable Continental Crust.

    ERIC Educational Resources Information Center

    Johnston, Arch C.; Kanter, Lisa R.

    1990-01-01

    Discussed are some of the reasons for earthquakes which occur in stable crust away from familiar zones at the ends of tectonic plates. Crust stability and the reactivation of old faults are described using examples from India and Australia. (CW)

  10. Shelf-Stable Food Safety

    MedlinePlus

    ... process of packing meat and poultry in glass bottles, corking them, and submerging them in boiling water. ... fsis.usda.gov. [ Top of Page ] Are any egg products shelf stable? Pasteurized, dried egg products can ...

  11. L-Band Transmit/Receive Module for Phase-Stable Array Antennas

    NASA Technical Reports Server (NTRS)

    Andricos, Constantine; Edelstein, Wendy; Krimskiy, Vladimir

    2008-01-01

    Interferometric synthetic aperture radar (InSAR) has been shown to provide very sensitive measurements of surface deformation and displacement on the order of 1 cm. Future systematic measurements of surface deformation will require this capability over very large areas (300 km) from space. To achieve these required accuracies, these spaceborne sensors must exhibit low temporal decorrelation and be temporally stable systems. An L-band (24-cmwavelength) InSAR instrument using an electronically steerable radar antenna is suited to meet these needs. In order to achieve the 1-cm displacement accuracy, the phased array antenna requires phase-stable transmit/receive (T/R) modules. The T/R module operates at L-band (1.24 GHz) and has less than 1- deg absolute phase stability and less than 0.1-dB absolute amplitude stability over temperature. The T/R module is also high power (30 W) and power efficient (60-percent overall efficiency). The design is currently implemented using discrete components and surface mount technology. The basic T/R module architecture is augmented with a calibration loop to compensate for temperature variations, component variations, and path loss variations as a function of beam settings. The calibration circuit consists of an amplitude and phase detector, and other control circuitry, to compare the measured gain and phase to a reference signal and uses this signal to control a precision analog phase shifter and analog attenuator. An architecture was developed to allow for the module to be bidirectional, to operate in both transmit and receive mode. The architecture also includes a power detector used to maintain a transmitter power output constant within 0.1 dB. The use of a simple, stable, low-cost, and high-accuracy gain and phase detector made by Analog Devices (AD8302), combined with a very-high efficiency T/R module, is novel. While a self-calibrating T/R module capability has been sought for years, a practical and cost-effective solution has

  12. Hadamard Factorization of Stable Polynomials

    NASA Astrophysics Data System (ADS)

    Loredo-Villalobos, Carlos Arturo; Aguirre-Hernández, Baltazar

    2011-11-01

    The stable (Hurwitz) polynomials are important in the study of differential equations systems and control theory (see [7] and [19]). A property of these polynomials is related to Hadamard product. Consider two polynomials p,q ∈ R[x]:p(x) = anxn+an-1xn-1+...+a1x+a0q(x) = bmx m+bm-1xm-1+...+b1x+b0the Hadamard product (p × q) is defined as (p×q)(x) = akbkxk+ak-1bk-1xk-1+...+a1b1x+a0b0where k = min(m,n). Some results (see [16]) shows that if p,q ∈R[x] are stable polynomials then (p×q) is stable, also, i.e. the Hadamard product is closed; however, the reciprocal is not always true, that is, not all stable polynomial has a factorization into two stable polynomials the same degree n, if n> 4 (see [15]).In this work we will give some conditions to Hadamard factorization existence for stable polynomials.

  13. Temporal Lobe Sclerosis Associated with Hippocampal Sclerosis in Temporal Lobe Epilepsy: Neuropathological Features

    PubMed Central

    Thom, Maria; Eriksson, Sofia; Martinian, Lillian; Caboclo, Luis O.; McEvoy, Andrew W.; Duncan, John S.; Sisodiya, Sanjay M.

    2009-01-01

    Widespread changes involving neocortical as well as mesial temporal lobe structures can be present in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). The incidence, pathology and clinical significance of neocortical temporal lobe sclerosis (TLS) are not well characterized. We identified TLS in 30 out of 272 surgically treated cases of HS. TLS was defined by variable reduction of neurons from cortical layers II/III and laminar gliosis; it was typically accompanied by additional architectural abnormalities of layer II, i.e. abnormal neuronal orientation and aggregation. Quantitative analysis including tessellation methods for the distribution of layer II neurons supported these observations. In 40% of cases there was a gradient of TLS with more severe involvement towards the temporal pole, possibly signifying involvement of hippocampal projection pathways. There was a history of a febrile seizure as an initial precipitating injury in 73% of patients with TLS compared to 36% without TLS; no other clinical differences TLS and non-TLS cases were identified. TLS was not evident pre-operatively by neuroimaging. No obvious effect of TLS on seizure outcome was noted after temporal lobe resection; 73% became seizure-free at 2 year follow up. In conclusion, approximately 11% of surgically treated HS is accompanied by TLS. TLS is likely an acquired process with accompanying re-organizational dysplasia and an extension of mesial temporal sclerosis rather than a separate pathological entity. PMID:19606061

  14. Functionally stable and phylogenetically diverse microbial enrichments from microbial fuel cells during wastewater treatment.

    PubMed

    Ishii, Shun'ichi; Suzuki, Shino; Norden-Krichmar, Trina M; Nealson, Kenneth H; Sekiguchi, Yuji; Gorby, Yuri A; Bretschger, Orianna

    2012-01-01

    Microbial fuel cells (MFCs) are devices that exploit microorganisms as biocatalysts to recover energy from organic matter in the form of electricity. One of the goals of MFC research is to develop the technology for cost-effective wastewater treatment. However, before practical MFC applications are implemented it is important to gain fundamental knowledge about long-term system performance, reproducibility, and the formation and maintenance of functionally-stable microbial communities. Here we report findings from a MFC operated for over 300 days using only primary clarifier effluent collected from a municipal wastewater treatment plant as the microbial resource and substrate. The system was operated in a repeat-batch mode, where the reactor solution was replaced once every two weeks with new primary effluent that consisted of different microbial and chemical compositions with every batch exchange. The turbidity of the primary clarifier effluent solution notably decreased, and 97% of biological oxygen demand (BOD) was removed after an 8-13 day residence time for each batch cycle. On average, the limiting current density was 1000 mA/m(2), the maximum power density was 13 mW/m(2), and coulombic efficiency was 25%. Interestingly, the electrochemical performance and BOD removal rates were very reproducible throughout MFC operation regardless of the sample variability associated with each wastewater exchange. While MFC performance was very reproducible, the phylogenetic analyses of anode-associated electricity-generating biofilms showed that the microbial populations temporally fluctuated and maintained a high biodiversity throughout the year-long experiment. These results suggest that MFC communities are both self-selecting and self-optimizing, thereby able to develop and maintain functional stability regardless of fluctuations in carbon source(s) and regular introduction of microbial competitors. These results contribute significantly toward the practical application

  15. Functionally Stable and Phylogenetically Diverse Microbial Enrichments from Microbial Fuel Cells during Wastewater Treatment

    PubMed Central

    Ishii, Shun'ichi; Suzuki, Shino; Norden-Krichmar, Trina M.; Nealson, Kenneth H.; Sekiguchi, Yuji; Gorby, Yuri A.; Bretschger, Orianna

    2012-01-01

    Microbial fuel cells (MFCs) are devices that exploit microorganisms as biocatalysts to recover energy from organic matter in the form of electricity. One of the goals of MFC research is to develop the technology for cost-effective wastewater treatment. However, before practical MFC applications are implemented it is important to gain fundamental knowledge about long-term system performance, reproducibility, and the formation and maintenance of functionally-stable microbial communities. Here we report findings from a MFC operated for over 300 days using only primary clarifier effluent collected from a municipal wastewater treatment plant as the microbial resource and substrate. The system was operated in a repeat-batch mode, where the reactor solution was replaced once every two weeks with new primary effluent that consisted of different microbial and chemical compositions with every batch exchange. The turbidity of the primary clarifier effluent solution notably decreased, and 97% of biological oxygen demand (BOD) was removed after an 8–13 day residence time for each batch cycle. On average, the limiting current density was 1000 mA/m2, the maximum power density was 13 mW/m2, and coulombic efficiency was 25%. Interestingly, the electrochemical performance and BOD removal rates were very reproducible throughout MFC operation regardless of the sample variability associated with each wastewater exchange. While MFC performance was very reproducible, the phylogenetic analyses of anode-associated electricity-generating biofilms showed that the microbial populations temporally fluctuated and maintained a high biodiversity throughout the year-long experiment. These results suggest that MFC communities are both self-selecting and self-optimizing, thereby able to develop and maintain functional stability regardless of fluctuations in carbon source(s) and regular introduction of microbial competitors. These results contribute significantly toward the practical application of

  16. Ultra-stable flashlamp-pumped laser

    NASA Astrophysics Data System (ADS)

    Brachmann, A.; Clendenin, J.; Galetto, T.; Maruyama, T.; Sodja, J.; Turner, J.; Woods, M.

    2003-07-01

    We present the design and experimental results for the flashlamp-pumped Ti:Sapphire laser system used at the Stanford Linear Accelerator Center (SLAC). This laser system is used in conjunction with the Polarized Electron Source to generate polarized electron beams for fixed target experiments (e.g. the E-158 experiment). The unique capabilities such as high pulse-to-pulse stability, long pulse length and high repetition rate is discussed. Emphasis is placed on recent modifications of the laser system, which allow ultra-stable operation with 0.5% rms intensity jitter.

  17. Visual information for judging temporal range

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.; Mowafy, Lyn

    1993-01-01

    Work in our laboratory suggests that pilots can extract temporal range information (i.e., the time to pass a given waypoint) directly from out-the-window motion information. This extraction does not require the use of velocity or distance, but rather operates solely on a 2-D motion cue. In this paper, we present the mathematical derivation of this information, psychophysical evidence of human observers' sensitivity, and possible advantages and limitations of basing vehicle control on this parameter.

  18. [Temporal meaning of suffering].

    PubMed

    Porée, J

    2015-09-01

    If we had to find a few simple words to express what a suffering human being experiences, no matter what ills are causing the suffering and no matter what circumstances underlie the ills themselves, we could unmistakably say that it is the experience of not being able to go on like this. Suffering can be described, in this same sense, as an alteration in temporality. However, describing suffering as such only makes sense if we already have a conception of normal temporality. Yet for this, philosophical tradition offers not one but four competing conceptions. In the present article, we begin by briefly presenting these different conceptions. We then show how each one sheds light, by way of contrast, on a phenomenon whose meaning thus appears to be essentially negative. But does this phenomenon have a negative meaning only? Doesn't it correspond as much to a transformation as an alteration of temporality? This is what we will strive to establish in the third part of the article by relating suffering to hope, in a paradoxical sense of the term. Of the four conceptions of time likely to shed a contrasting light on the upheavals that suffering introduces into our life experience, the one described by Aristotle in Physics is historically the first. In particular, the notion of succession originates therein. But this conception does not account for what makes time the unit of a past, a present, and a future. In Book XI of Confessions, St. Augustine situated this unit not in nature but in the human mind. Hence, his definition of time as a distension of the soul and the necessary division into physical time and psychic time it entails. Husserl's Lessons on the phenomenology of the consciousness of internal time lend credit to this division, but they illuminate only the internal constitution of the "present", which is at the heart of the psychological conception of time. In Being and Time, Heidegger breaks away from this long-standing tradition; in his view, physical time

  19. The influence of temporal phase differences on texture segmentation.

    PubMed

    Leonards, U; Singer, W; Fahle, M

    1996-09-01

    Scene segmentation and perceptual grouping are important operations in visual processing. Pattern elements constituting individual perceptual objects need to be segregated from those of other objects and the background and have to be bound together for further joint evaluation. Both textural (spatial) and temporal cues are exploited for this grouping operation. Thus, pattern elements might get bound that share certain textural features and/or appear in close spatial or temporal contiguity. However, results on the involvement of temporal cues in perceptual grouping are contradictory [Kiper et al. (1991). Society for Neuroscience Abstracts, 17, 1209; Fahle (1993). Proceedings of the Royal Society of London B, 254, 199-203]. We therefore reinvestigated the relative contributions of temporal and spatial cues and their interactions in a texture-segmentation paradigm. Our data show that the visual system can segregate figures solely on the basis of temporal cues if the temporal offset between figure and ground elements exceeds 10 msec. Moreover, segregation of figures defined by orientation differences among pattern elements is facilitated by additional temporal cues if these define the same figure. If temporal and textural cues define different figures, the two cues compete and only the more salient pattern is perceived. By contrast, the detection of a figure defined by orientation is not impaired by conflicting temporal cues if these do not define a figure themselves and do not exceed offset intervals of 100 msec. These results indicate the existence of a flexible binding mechanism that exploits both temporal and textural cues either alone or in combination if they serve perceptual grouping but can exclude either of the two cues if they are in conflict or do not define a figure. It is proposed that this flexibility is achieved by the implementation of two segmentation mechanisms which differ in their sensitivity for spatial and temporal cues and interact in a

  20. Temporal Large-Eddy Simulation

    NASA Technical Reports Server (NTRS)

    Pruett, C. D.; Thomas, B. C.

    2004-01-01

    In 1999, Stolz and Adams unveiled a subgrid-scale model for LES based upon approximately inverting (defiltering) the spatial grid-filter operator and termed .the approximate deconvolution model (ADM). Subsequently, the utility and accuracy of the ADM were demonstrated in a posteriori analyses of flows as diverse as incompressible plane-channel flow and supersonic compression-ramp flow. In a prelude to the current paper, a parameterized temporal ADM (TADM) was developed and demonstrated in both a priori and a posteriori analyses for forced, viscous Burger's flow. The development of a time-filtered variant of the ADM was motivated-primarily by the desire for a unifying theoretical and computational context to encompass direct numerical simulation (DNS), large-eddy simulation (LES), and Reynolds averaged Navier-Stokes simulation (RANS). The resultant methodology was termed temporal LES (TLES). To permit exploration of the parameter space, however, previous analyses of the TADM were restricted to Burger's flow, and it has remained to demonstrate the TADM and TLES methodology for three-dimensional flow. For several reasons, plane-channel flow presents an ideal test case for the TADM. Among these reasons, channel flow is anisotropic, yet it lends itself to highly efficient and accurate spectral numerical methods. Moreover, channel-flow has been investigated extensively by DNS, and a highly accurate data base of Moser et.al. exists. In the present paper, we develop a fully anisotropic TADM model and demonstrate its utility in simulating incompressible plane-channel flow at nominal values of Re(sub tau) = 180 and Re(sub tau) = 590 by the TLES method. The TADM model is shown to perform nearly as well as the ADM at equivalent resolution, thereby establishing TLES as a viable alternative to LES. Moreover, as the current model is suboptimal is some respects, there is considerable room to improve TLES.

  1. [Surgical results of dissection of the superficial temporal artery in patients with preglaucoma and initial open-angle glaucoma].

    PubMed

    Shilkin, G A; Iartseva, N S; Mironova, E M; Oreshkina, R M; Mikhaĭlova, G D

    1989-01-01

    Results of superficial temporal artery dissection performed in 42 patients (44 eyes) with preglaucoma and initial open-angle glaucoma have shown no impairement of visual field, visual acuity, optic disc in the period from 0.5 to 1.5 years after it. The increased linear rate of bloodflow after the operation remained stable in 17 eyes of patients with preglaucoma and in 14 eyes of patients with glaucoma. Intraocular pressure became normalized in 20 and 19 eyes as well as intraocular fluid outflow in 14 and 13 eyes, respectively. In both groups there was a tendency to normalization of retinal functions and hydrodynamics of the eye. Thus, the operation produces improvement of regional bloodflow, tonographic and electrophysiologic indices. Its usage is considered to be reasonable, but, when determining indications to it, an individual approach is necessary. PMID:2755669

  2. Behavioral Sensitivity of Temporally Modulated Striatal Neurons

    PubMed Central

    Portugal, George S.; Wilson, A. George; Matell, Matthew S.

    2011-01-01

    Recent investigations into the neural mechanisms that underlie temporal perception have revealed that the striatum is an important contributor to interval timing processes, and electrophysiological recording studies have shown that the firing rates of striatal neurons are modulated by the time in a trial at which an operant response is made. However, it remains unclear whether striatal firing rate modulations are related to the passage of time alone (i.e., whether temporal information is represented in an “abstract” manner independent of other attributes of biological importance), or whether this temporal information is embedded within striatal activity related to co-occurring contextual information, such as motor behaviors. This study evaluated these two hypotheses by recording from striatal neurons while rats performed a temporal production task. Rats were trained to respond at different nosepoke apertures for food reward under two simultaneously active reinforcement schedules: a variable-interval (VI-15 s) schedule and a fixed-interval (FI-15 s) schedule of reinforcement. Responding during a trial occurred in a sequential manner composing three phases; VI responding, FI responding, VI responding. The vast majority of task-sensitive striatal neurons (95%) varied their firing rates associated with equivalent behaviors (e.g., periods in which their snout was held within the nosepoke) across these behavioral phases, and 96% of cells varied their firing rates for the same behavior within a phase, thereby demonstrating their sensitivity to time. However, in a direct test of the abstract timing hypothesis, 91% of temporally modulated “hold” cells were further modulated by the overt motor behaviors associated with transitioning between nosepokes. As such, these data are inconsistent with the striatum representing time in an “abstract’ manner, but support the hypothesis that temporal information is embedded within contextual and motor functions of the

  3. Pre-semantically defined temporal windows for cognitive processing

    PubMed Central

    Pöppel, Ernst

    2009-01-01

    Neuronal oscillations of different frequencies are hypothesized to be basic for temporal perception; this theoretical concept provides the frame to discuss two temporal mechanisms that are thought to be essential for cognitive processing. One such mechanism operates with periods of oscillations in the range of some tens of milliseconds, and is used for complexity reduction of temporally and spatially distributed neuronal activities. Experimental evidence comes from studies on temporal-order threshold, choice reaction time, single-cell activities, evoked responses in neuronal populations or latency distributions of oculomotor responses. The other mechanism refers to pre-semantic integration in the temporal range of approximately 2–3 s. Experimental evidence comes from studies on temporal reproduction, sensorimotor synchronization, intentional movements, speech segmentation, the shift rate of ambiguous stimuli in the visual or auditory modality or the temporal modulation of the mismatch negativity. These different observations indicate the existence of a universal process of temporal integration underlying the mental machinery. This process is believed to be basic for maintenance and change of perceptual identity. Owing to the omnipresence of this kind of temporal segmentation, it is suggested to use this process for a pragmatic definition of the states of being conscious or the ‘subjective presence’. PMID:19487191

  4. Audiotactile interactions in temporal perception.

    PubMed

    Occelli, Valeria; Spence, Charles; Zampini, Massimiliano

    2011-06-01

    In the present review, we focus on how commonalities in the ontogenetic development of the auditory and tactile sensory systems may inform the interplay between these signals in the temporal domain. In particular, we describe the results of behavioral studies that have investigated temporal resolution (in temporal order, synchrony/asynchrony, and simultaneity judgment tasks), as well as temporal numerosity perception, and similarities in the perception of frequency across touch and hearing. The evidence reviewed here highlights features of audiotactile temporal perception that are distinctive from those seen for other pairings of sensory modalities. For instance, audiotactile interactions are characterized in certain tasks (e.g., temporal numerosity judgments) by a more balanced reciprocal influence than are other modality pairings. Moreover, relative spatial position plays a different role in the temporal order and temporal recalibration processes for audiotactile stimulus pairings than for other modality pairings. The effect exerted by both the spatial arrangement of stimuli and attention on temporal order judgments is described. Moreover, a number of audiotactile interactions occurring during sensory-motor synchronization are highlighted. We also look at the audiotactile perception of rhythm and how it may be affected by musical training. The differences emerging from this body of research highlight the need for more extensive investigation into audiotactile temporal interactions. We conclude with a brief overview of some of the key issues deserving of further research in this area. PMID:21400125

  5. Temporal uncertainty of geographical information

    NASA Astrophysics Data System (ADS)

    Shu, Hong; Qi, Cuihong

    2005-10-01

    Temporal uncertainty is a crossing point of temporal and error-aware geographical information systems. In Geoinformatics, temporal uncertainty is of the same importance as spatial and thematic uncertainty of geographical information. However, until very recently, the standard organizations of ISO/TC211 and FGDC subsequently claimed that temporal uncertainty is one of geospatial data quality elements. Over the past decades, temporal uncertainty of geographical information is modeled insufficiently. To lay down a foundation of logically or physically modeling temporal uncertainty, this paper is aimed to clarify the semantics of temporal uncertainty to some extent. The general uncertainty is conceptualized with a taxonomy of uncertainty. Semantically, temporal uncertainty is progressively classified into uncertainty of time coordinates, changes, and dynamics. Uncertainty of multidimensional time (valid time, database time, and conceptual time, etc.) has been emphasized. It is realized that time scale (granularity) transition may lead to temporal uncertainty because of missing transition details. It is dialectically concluded that temporal uncertainty is caused by the complexity of the human-machine-earth system.

  6. Comprehensive Retrieval of Spatio-temporal Variations in Atmospheric Radionuclides just after the Fukushima Accident by Analyzing Filter-tapes of Operational Air Pollution Monitoring Stations in Eastern Japan

    NASA Astrophysics Data System (ADS)

    Tsuruta, H.; Oura, Y.; Ebihara, M.; Ohara, T.; Nakajima, T.

    2015-12-01

    After the Fukushima Daiichi Nuclear Power Station (FD1NPS) accident on March 11, 2011, many datasets have been available of deposition density of radionuclides in soils in eastern Japan. By contrast, no time-series data of atmospheric radionuclides has been measured in the Fukushima prefecture (FP), although very limited data is available in the Tokyo metropolitan area (TMA) located more than 170 km southwest of the FD1NPS. As a result, atmospheric transport models simulating the atmospheric concentrations and surface deposition of radionuclides have large uncertainty, as well as the estimate of release rate of source terms and of internal exposure from inhalation. One year after the accident, we collected the used filter-tapes installed in Suspended Particulate Matter (SPM) monitors with beta-ray attenuation method operated by local governments in the air pollution monitoring network of eastern Japan. By measuring radionuclides in SPM on the filter-tapes, we retrieved hourly atmospheric Cs-134 and Cs-137 concentrations during March 12-23, 2011, when atmospheric, aquatic, and terrestrial environments were seriously suffered in most of eastern Japan. Until now, we measured hourly radiocesium at around 100 SPM sites in the southern Tohoku region (ST) including the FP and in the TMA. By analysing the dataset, nine major plumes with Cs-137 concentrations higher than 10 Bq m-3 were found, and some plumes were newly found in this study. A local area of relatively high Cs-137 deposition density in the TMA by precipitation on the morning of March 21, was consistent with an area where the time-integrated atmospheric Cs-137 concentrations were also high due to the transport of a plume on the morning of March 21. In the FP, however, the correlation was not so clear. High radionuclides trapped in a cloud layer might be transported to the ST with relatively high Cs-137 deposition densities, because the atmospheric Cs-137 concentrations were under the detection limit.

  7. Multi-stable cylindrical lattices

    NASA Astrophysics Data System (ADS)

    Pirrera, Alberto; Lachenal, Xavier; Daynes, Stephen; Weaver, Paul M.; Chenchiah, Isaac V.

    2013-11-01

    We present a cylindrical lattice structure that mimics the behaviour of the virus bacteriophage T4 in having two (or more) stable states which differ in their radii and length. While the virus achieves bistability through molecular mechanisms we use composite materials to exploit the interplay between pre-stress, material properties and structural geometry. We demonstrate (computationally) that multi-stability is a robust phenomenon. We also show (analytically) that it is possible to choose the design variables so that the energy is independent of the radius, thus resulting in every state of the structure being stable.

  8. Temporal dispersion of a spectrometera)

    NASA Astrophysics Data System (ADS)

    Visco, A.; Drake, R. P.; Froula, D. H.; Glenzer, S. H.; Pollock, B. B.

    2008-10-01

    The temporal dispersion of an optical spectrometer has been characterized for a variety of conditions related to optical diagnostics to be fielded at the National Ignition Facility (e.g., full-aperture backscatter station, Thomson scattering). Significant time smear is introduced into these systems by the path length difference through the spectrometer. The temporal resolution is shown to depend only on the order of the grating, wavelength, and the number of grooves illuminated. To enhance the temporal resolution, the spectral gratings can be masked limiting the number of grooves illuminated. Experiments have been conducted to verify these calculations. The size and shape of masks are investigated and correlated with the exact shape of the temporal instrument function, which is required when interpreting temporally resolved data. The experiments used a 300 fs laser pulse and a picosecond optical streak camera to determine the temporal dispersion. This was done for multiple spectral orders, gratings, and optical masks.

  9. Temporal dispersion of a spectrometer.

    PubMed

    Visco, A; Drake, R P; Froula, D H; Glenzer, S H; Pollock, B B

    2008-10-01

    The temporal dispersion of an optical spectrometer has been characterized for a variety of conditions related to optical diagnostics to be fielded at the National Ignition Facility (e.g., full-aperture backscatter station, Thomson scattering). Significant time smear is introduced into these systems by the path length difference through the spectrometer. The temporal resolution is shown to depend only on the order of the grating, wavelength, and the number of grooves illuminated. To enhance the temporal resolution, the spectral gratings can be masked limiting the number of grooves illuminated. Experiments have been conducted to verify these calculations. The size and shape of masks are investigated and correlated with the exact shape of the temporal instrument function, which is required when interpreting temporally resolved data. The experiments used a 300 fs laser pulse and a picosecond optical streak camera to determine the temporal dispersion. This was done for multiple spectral orders, gratings, and optical masks. PMID:19044687

  10. Temporal waveguides for optical pulses

    DOE PAGESBeta

    Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

    2016-05-12

    Here we discuss, temporal total internal reflection (TIR), in analogy to the conventional TIR of an optical beam at a dielectric interface, is the total reflection of an optical pulse inside a dispersive medium at a temporal boundary across which the refractive index changes. A pair of such boundaries separated in time acts as the temporal analog of planar dielectric waveguides. We study the propagation of optical pulses inside such temporal waveguides, both analytically and numerically, and show that the waveguide supports a finite number of temporal modes. We also discuss how a single-mode temporal waveguide can be created inmore » practice. In contrast with the spatial case, the confinement can occur even when the central region has a lower refractive index.« less

  11. Temporal Representation in Semantic Graphs

    SciTech Connect

    Levandoski, J J; Abdulla, G M

    2007-08-07

    A wide range of knowledge discovery and analysis applications, ranging from business to biological, make use of semantic graphs when modeling relationships and concepts. Most of the semantic graphs used in these applications are assumed to be static pieces of information, meaning temporal evolution of concepts and relationships are not taken into account. Guided by the need for more advanced semantic graph queries involving temporal concepts, this paper surveys the existing work involving temporal representations in semantic graphs.

  12. Synthesis of thermally stable polymers

    NASA Technical Reports Server (NTRS)

    Butler, G. B.

    1978-01-01

    The reaction of bis triazo linediones with divinyl esters and substituted styrenes was investigated. Twenty new polymers were derived via reaction of two previously synthesized bis triazol linediones and four new bis atriazol linediones with eight styrenes. The structure and polymer properties of these thermally stable polymers was examined. The reaction of triazo linediones with enol esters was also considered.

  13. Bayesian stable isotope mixing models

    EPA Science Inventory

    In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixtur...

  14. Stable interactions via proper deformations

    NASA Astrophysics Data System (ADS)

    Kaparulin, D. S.; Lyakhovich, S. L.; Sharapov, A. A.

    2016-04-01

    A new method is proposed for switching on interactions that are compatible with global symmetries and conservation laws of the original free theory. The method is applied to the control of stability in Lagrangian and non-Lagrangian theories with higher derivatives. By way of illustration, a wide class of stable interactions is constructed for the Pais-Uhlenbeck oscillator.

  15. Stable Black Families. Final Report.

    ERIC Educational Resources Information Center

    Gary, Lawrence E.; And Others

    This document is the final report of a study conducted to determine what factors contribute to strong Black family life and how these strong families solve problems, in order to add to the knowledge base on stable families so as to enhance practical intervention with families in need, and to identify models of self-help strategies used by stable…

  16. Keyhole epilepsy surgery: corticoamygdalohippocampectomy for mesial temporal sclerosis.

    PubMed

    Yang, Peng-Fan; Zhang, Hui-Jian; Pei, Jia-Sheng; Lin, Qiao; Mei, Zhen; Chen, Zi-Qian; Jia, Yan-Zeng; Zhong, Zhong-Hui; Zheng, Zhi-Yong

    2016-01-01

    Surgical approaches for medically refractory mesial temporal lobe epilepsy (MTLE) that previously have been reported include anterior temporal lobectomy (ATL), transcortical selective amygdalohippocampectomy, transsylvian amygdalohippocampectomy, and subtemporal amygdalohippocampectomy. Each approach has its advantages and potential pitfalls. The purpose of this report is to describe our technique of keyhole corticoamygdalohippocampectomy for patients with MTLE due to hippocampal sclerosis. Operations were performed through a 6-cm vertical linear incision and a low 2.5-cm keyhole craniotomy at the anterior squamous temporal bone. Resection of the anterior-most portions of the middle and inferior temporal gyri provided a cylinder-like corridor to the mesial temporal lobe. Identification of the temporal horn through a basal approach was followed by resection of the amygdala, uncus, and hippocampus-parahippocampal gyrus. This 9-year series included 683 patients with a minimum follow-up duration of 2 years. Surgery times were short (range, 1 h 35 min to 2 h 30 min). Only a small percentage of patients had complications (1.76%), and the rate of Engel Class I seizure-free outcome was 87%. No overt speech problems or visual field deficits were identified. Compared with the most popular conventional trans-middle temporal gyrus approach, this technique can make the operation easier, safer, and less traumatic to functional lateral neocortex. PMID:26277790

  17. Stable isotopic compositions in Australian precipitation

    NASA Astrophysics Data System (ADS)

    Liu, Jianrong; Fu, Guobin; Song, Xianfang; Charles, Stephen P.; Zhang, Yinghua; Han, Dongmei; Wang, Shiqin

    2010-12-01

    Stable deuterium (δD) and oxygen-18 (δ18O) isotopes in 1962 to 2002 precipitation from the seven Australian stations of the Global Network of Isotopes in Precipitation (GNIP) were used to investigate isotope characteristics including temporal and spatial distributions across different regions of Australia. On the basis of 1534 samples, the local meteoric water line (LMWL) was established as δD = 7.10δ18O + 8.21. δ18O showed a depletion trend from north and south to central Australia (a continental effect) and from west to east. Precipitation amount effects were generally greater than temperature effects, with quadratic or logarithmic correlations describing δ/T and δ/P better than linear relationships. Nonlinear stepwise regression was used to determine the significant meteorological control factors for each station, explaining about 50% or more of the δ18O variations. Geographical control factors for δ18O were given by the relationship δ18O (‰) = -0.005 longitude (°) - 0.034 latitude (°)-0.003 altitude (m) - 4.753. Four different types of d-excess patterns demonstrated particular precipitation formation conditions for four major seasonal rainfall zones. Finally, wavelet coherence (WTC) between δ18O and SOI confirmed that the influence of ENSO decreased from east and north to west Australia.

  18. Qualitative and temporal reasoning in engine behavior analysis

    NASA Technical Reports Server (NTRS)

    Dietz, W. E.; Stamps, M. E.; Ali, M.

    1987-01-01

    Numerical simulation models, engine experts, and experimental data are used to generate qualitative and temporal representations of abnormal engine behavior. Engine parameters monitored during operation are used to generate qualitative and temporal representations of actual engine behavior. Similarities between the representations of failure scenarios and the actual engine behavior are used to diagnose fault conditions which have already occurred, or are about to occur; to increase the surveillance by the monitoring system of relevant engine parameters; and to predict likely future engine behavior.

  19. Temporal Variations in Jupiter's Atmosphere

    NASA Technical Reports Server (NTRS)

    Simon-Miller, Amy A.; Chanover, N. J.; Yanamandra-Fisher, P.; Hammel, H. B.; dePater, I.; Noll, K.; Wong, M.; Clarke, J.; Sanchez-Levega, A.; Orton, G. S.; Gonzaga, S.

    2009-01-01

    In recent years, Jupiter has undergone many atmospheric changes from storms turning red to global. cloud upheavals, and most recently, a cornet or asteroid impact. Yet, on top of these seemingly random changes events there are also periodic phenomena, analogous to observed Earth and Saturn atmospheric oscillations. We will present 15 years of Hubble data, from 1994 to 2009, to show how the equatorial tropospheric cloud deck and winds have varied over that time, focusing on the F953N, F41 ON and F255W filters. These filters give leverage on wind speeds plus cloud opacity, cloud height and tropospheric haze thickness, and stratospheric haze, respectively. The wind data consistently show a periodic oscillation near 7-8 S latitude. We will discuss the potential for variations with longitude and cloud height, within the calibration limits of those filters. Finally, we will discuss the role that large atmospheric events, such as the impacts in 1994 and 2009, and the global upheaval of 2007, have on temporal studies, This work was supported by a grant from the NASA Planetary Atmospheres Program. HST observational support was provided by NASA through grants from Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract NAS5-26555.

  20. EXAMINING THE TEMPORAL VARIABILITY OF AMMONIA AND NITRIC OXIDE EMISSIONS FROM AGRICULTURAL PROCESSES

    EPA Science Inventory

    This paper examines the temporal variability of airborne emissions of ammonia from livestock operations and fertilizer application and nitric oxide from soils. In the United States, the livestock operations and fertilizer categories comprise the majority of the ammonia emissions...

  1. Combining spatial and temporal expectations to improve visual perception

    PubMed Central

    Rohenkohl, Gustavo; Gould, Ian C.; Pessoa, Jéssica; Nobre, Anna C.

    2014-01-01

    The importance of temporal expectations in modulating perceptual functions is increasingly recognized. However, the means through which temporal expectations can bias perceptual information processing remains ill understood. Recent theories propose that modulatory effects of temporal expectations rely on the co-existence of other biases based on receptive-field properties, such as spatial location. We tested whether perceptual benefits of temporal expectations in a perceptually demanding psychophysical task depended on the presence of spatial expectations. Foveally presented symbolic arrow cues indicated simultaneously where (location) and when (time) target events were more likely to occur. The direction of the arrow indicated target location (80% validity), while its color (pink or blue) indicated the interval (80% validity) for target appearance. Our results confirmed a strong synergistic interaction between temporal and spatial expectations in enhancing visual discrimination. Temporal expectation significantly boosted the effectiveness of spatial expectation in sharpening perception. However, benefits for temporal expectation disappeared when targets occurred at unattended locations. Our findings suggest that anticipated receptive-field properties of targets provide a natural template upon which temporal expectations can operate in order to help prioritize goal-relevant events from early perceptual stages. PMID:24722562

  2. Medical Temporal-Knowledge Discovery via Temporal Abstraction

    PubMed Central

    Moskovitch, Robert; Shahar, Yuval

    2009-01-01

    Medical knowledge includes frequently occurring temporal patterns in longitudinal patient records. These patterns are not easily detectable by human clinicians. Current knowledge could be extended by automated temporal data mining. However, multivariate time-oriented data are often present at various levels of abstraction and at multiple temporal granularities, requiring a transformation into a more abstract, yet uniform dimension suitable for mining. Temporal abstraction (of both the time and value dimensions) can transform multiple types of point-based data into a meaningful, time-interval-based data representation, in which significant, interval-based temporal patterns can be discovered. We introduce a modular, fast time-interval mining method, KarmaLego, which exploits the transitivity inherent in temporal relations. We demonstrate the usefulness of KarmaLego in finding meaningful temporal patterns within a set of records of diabetic patients; several patterns seem to have a different frequency depending on gender. We also suggest additional uses of the discovered patterns for temporal clustering of the mined population and for classifying multivariate time series. PMID:20351898

  3. Superficial temporal artery to proximal posterior cerebral artery bypass through the anterior temporal approach

    PubMed Central

    Takeuchi, Satoru; Tanikawa, Rokuya; Tsuboi, Toshiyuki; Noda, Kosumo; Oda, Junpei; Miyata, Shiro; Ota, Nakao; Yoshikane, Tsutomu; Kamiyama, Hiroyasu

    2015-01-01

    Background: The superficial temporal artery (STA) to proximal posterior cerebral artery (PCA) (P2 segment) bypass is one of the most difficult procedures to perform because the proximal PCA is located deep and high within the ambient cistern. STA to proximal PCA bypass is usually performed through a subtemporal approach or posterior transpetrosal approach, and rarely through a transsylvian approach. The aim of this study was to describe the operative technique of STA to proximal PCA bypass through a modified transsylvian approach (anterior temporal approach). Methods: STA to proximal PCA bypass was performed through an anterior temporal approach in three patients with intracranial aneurysm. We describe the details of the surgical technique. Results: The STA was successfully anastomosed to the proximal PCA in all cases. One patient suffered hemiparesis and aphasia due to infarction in the anterior thalamoperforating artery territory. Conclusions: STA to proximal PCA bypass can be performed through an anterior temporal approach in selected patients. We recommend that every precaution, including complete hemostasis, placement of cellulose sponges beneath the recipient artery to elevate the site of the anastomosis, and placement of a continuous drainage tube at the bottom of the operative field to avoid blood contamination during the anastomosis, should be taken to shorten the temporary occlusion time. PMID:26097774

  4. Temporal characterization of a multi-wavelength Brillouin–erbium fiber laser

    NASA Astrophysics Data System (ADS)

    Lambin Iezzi, Victor; Büttner, Thomas F. S.; Tehranchi, Amirhossein; Loranger, Sébastien; Kabakova, Irina V.; Eggleton, Benjamin J.; Kashyap, Raman

    2016-05-01

    This paper provides the first detailed temporal characterization of a multi-wavelength-Brillouin–erbium fiber laser (MWBEFL) by measuring the optical intensity of the individual frequency channels with high temporal resolution. It is found that the power in each channel is highly unstable due to the excitation of several cavity modes for typical conditions of operation. Also provided is the real-time measurements of the MWBEFL output power for two configurations that were previously reported to emit phase-locked picosecond pulse trains, concluded from their autocorrelation measurements. Real-time measurements reveal a high degree of instability without the formation of a stable pulse train. Finally, we model the MWBEFL using coupled wave equations describing the evolution of the Brillouin pump, Stokes and acoustic waves in the presence of stimulated Brillouin scattering, and the optical Kerr effect. A good qualitative consistency between the simulation and experimental results is evident, in which the interference signal at the output shows strong instability as well as the chaotic behavior due to the dynamics of participating pump and Stokes waves.

  5. Temporal Dynamics of the Human Vaginal Microbiota

    PubMed Central

    Gajer, Pawel; Brotman, Rebecca M.; Bai, Guoyun; Sakamoto, Joyce; Schütte, Ursel M.E.; Zhong, Xue; Koenig, Sara S.K.; Fu, Li; Ma, Zhanshan; Zhou, Xia; Abdo, Zaid; Forney, Larry J.; Ravel, Jacques

    2012-01-01

    Elucidating the factors that impinge on the stability of bacterial communities in the vagina may help in predicting the risk of diseases that affect women’s health. Here, we describe the temporal dynamics of the composition of vaginal bacterial communities in 32 reproductive age women over a 16-week period. The analysis revealed the dynamics of five major classes of bacterial communities and showed that some communities change markedly over short time periods, whereas others are relatively stable. Modeling community stability using new quantitative measures indicates that deviation from stability correlates with time in the menstrual cycle, bacterial community composition and sexual activity. The women studied are healthy, thus it appears that neither variation in community composition per se, nor higher levels of observed diversity (co-dominance) are necessarily indicative of dysbiosis, in which there is microbial imbalance accompanied by symptoms. PMID:22553250

  6. Rapid auditory learning of temporal gap detection.

    PubMed

    Mishra, Srikanta K; Panda, Manasa R

    2016-07-01

    The rapid initial phase of training-induced improvement has been shown to reflect a genuine sensory change in perception. Several features of early and rapid learning, such as generalization and stability, remain to be characterized. The present study demonstrated that learning effects from brief training on a temporal gap detection task using spectrally similar narrowband noise markers defining the gap (within-channel task), transfer across ears, however, not across spectrally dissimilar markers (between-channel task). The learning effects associated with brief training on a gap detection task were found to be stable for at least a day. These initial findings have significant implications for characterizing early and rapid learning effects. PMID:27475211

  7. Stable continuous-time autoregressive process driven by stable subordinator

    NASA Astrophysics Data System (ADS)

    Wyłomańska, Agnieszka; Gajda, Janusz

    2016-02-01

    In this paper we examine the continuous-time autoregressive moving average process driven by α-stable Lévy motion delayed by inverse stable subordinator. This process can be applied to high-frequency data with visible jumps and so-called "trapping-events". Those properties are often visible in financial time series but also in amorphous semiconductors, technical data describing the rotational speed of a machine working under various load regimes or data related to indoor air quality. We concentrate on the main characteristics of the examined subordinated process expressed in the language of the measures of dependence which are main tools used in statistical investigation of real data. However, because the analyzed system is based on the α-stable distribution therefore we cannot consider here the correlation (or covariance) as a main measure which indicates at the dependence inside the process. In the paper we examine the codifference, the more general measure of dependence defined for wide class of processes. Moreover we present the simulation procedure of the considered system and indicate how to estimate its parameters. The theoretical results we illustrate by the simulated data analysis.

  8. Reaction diffusion equation with spatio-temporal delay

    NASA Astrophysics Data System (ADS)

    Zhao, Zhihong; Rong, Erhua

    2014-07-01

    We investigate reaction-diffusion equation with spatio-temporal delays, the global existence, uniqueness and asymptotic behavior of solutions for which in relation to constant steady-state solution, included in the region of attraction of a stable steady solution. It is shown that if the delay reaction function satisfies some conditions and the system possesses a pair of upper and lower solutions then there exists a unique global solution. In terms of the maximal and minimal constant solutions of the corresponding steady-state problem, we get the asymptotic stability of reaction-diffusion equation with spatio-temporal delay. Applying this theory to Lotka-Volterra model with spatio-temporal delay, we get the global solution asymptotically tend to the steady-state problem's steady-state solution.

  9. Changes in multifractal properties for stable angina pectoris

    NASA Astrophysics Data System (ADS)

    Knežević, Andrea; Martinis, Mladen; Krstačić, Goran; Vargović, Emil

    2005-12-01

    The multifractal approach has been applied to temporal fluctuations of heartbeat (RR) intervals, measured in various regimes of physical activity (ergometric data), taken from healthy subjects and those having stable angina pectoris (SAP). The problem we address here is whether SAP changes multifractality observed in healthy subjects. The G-moment method is used to analyse the multifractal spectrum. It is observed that both sets of data characterize multifractality, but a different trend in multifractal behaviour is found for SAP disease, under pronounced physical activity.

  10. Using stable isotopes of water to infer wetland hydrological dynamics

    NASA Astrophysics Data System (ADS)

    Clay, A.; Bradley, C.; Gerrard, A. J.; Leng, M. J.

    This paper considers the potential of oxygen and hydrogen isotope ratios to identify spatial and temporal changes in the water source of a lowland headwater wetland situated adjacent to the River Tern in Shropshire, UK. Stable isotope composition (d18O) of end-members varied between -7.5 and -8.0‰ for groundwater, -7.3 and -8.5‰ for river-water and -4.5 and -8.0‰ for precipitation. Water samples were extracted from six nests each comprising three porous cup samplers at depths of 0.2 m, 0.5 m and 1.0 m between June 2000 and October 2001, and their isotope compositions determined. Groundwater appears to be the main source of water to the wetland, but stable isotope ratios enable seasonal variations in the contribution of precipitation to be determined, and indicate the extent of precipitation storage within the wetland.

  11. Temporal Scattering And Response

    SciTech Connect

    McLeod, R. R.; Ray, S. L.; Laguna, G.; Allison, M.; Cabral, B.

    1992-12-15

    TSAR2.3 (Temporal Scattering and Response) is a finite-difference time-domain electromagnetics code suite. TSAR2.3 is a software package for simulating the interactions of electromagnetic waves with linear materials through the use of the finite-difference time-domain method. The code suite contains grid generation, grid verification, input-file creation and post-processing utilities. The physics package, written in Fortran 77, can be pre-processed to run on many different architectures including Cray, Vax and many Unix workstations. Tools are provided to easily port the code to new computers. The physics package is an efficient, flexible electromagnetic simulator. A body under study can be represented as a three-dimensional grid of materials with arbitrary linear properties. This grid can be simulated in a number of ways including incident plane waves, dipoles, and arbitrary incident fields. The grid can be terminated with numerous boundary conditions including free-space radiation, electric conductor, or magnetic conductor. Projection to the far-field in both the time and frequency domains is possible. This distribution includes make files for installing and maintaining the entire code suite.

  12. Massive Temporal Lobe Cholesteatoma

    PubMed Central

    Waidyasekara, Pasan; Dowthwaite, Samuel A.; Stephenson, Ellison; Bhuta, Sandeep; McMonagle, Brent

    2015-01-01

    Introduction. Intracranial extension of cholesteatoma is rare. This may occur de novo or recur some time later either contiguous with or separate to the site of the original cholesteatoma. Presentation of Case. A 63-year-old female presented to a tertiary referral hospital with a fluctuating level of consciousness, fever, headache, and right-sided otorrhoea, progressing over several days. Her past medical history included surgery for right ear cholesteatoma and drainage of intracranial abscess 23 years priorly. There had been no relevant symptoms in the interim until 6 weeks prior to this presentation. Imaging demonstrated a large right temporal lobe mass contiguous with the middle ear and mastoid cavity with features consistent with cholesteatoma. The patient underwent a combined transmastoid/middle fossa approach for removal of the cholesteatoma and repair of the tegmen dehiscence. The patient made an uneventful recovery and remains well over 12 months later. Conclusion. This case presentation details a large intracranial cholesteatoma which had extended through a tegmen tympani dehiscence from recurrent right ear cholesteatoma treated by modified radical mastoidectomy over two decades priorly. There was a completely asymptomatic progression of disease until several weeks prior to this presentation. PMID:25821620

  13. Temporal Scattering And Response

    Energy Science and Technology Software Center (ESTSC)

    1992-12-15

    TSAR2.3 (Temporal Scattering and Response) is a finite-difference time-domain electromagnetics code suite. TSAR2.3 is a software package for simulating the interactions of electromagnetic waves with linear materials through the use of the finite-difference time-domain method. The code suite contains grid generation, grid verification, input-file creation and post-processing utilities. The physics package, written in Fortran 77, can be pre-processed to run on many different architectures including Cray, Vax and many Unix workstations. Tools are provided tomore » easily port the code to new computers. The physics package is an efficient, flexible electromagnetic simulator. A body under study can be represented as a three-dimensional grid of materials with arbitrary linear properties. This grid can be simulated in a number of ways including incident plane waves, dipoles, and arbitrary incident fields. The grid can be terminated with numerous boundary conditions including free-space radiation, electric conductor, or magnetic conductor. Projection to the far-field in both the time and frequency domains is possible. This distribution includes make files for installing and maintaining the entire code suite.« less

  14. Spatial Grouping Determines Temporal Integration

    ERIC Educational Resources Information Center

    Hermens, Frouke; Scharnowski, Frank; Herzog, Michael H.

    2009-01-01

    To make sense out of a continuously changing visual world, people need to integrate features across space and time. Despite more than a century of research, the mechanisms of features integration are still a matter of debate. To examine how temporal and spatial integration interact, the authors measured the amount of temporal fusion (a measure of…

  15. Temporal Processing and Reading Disability.

    ERIC Educational Resources Information Center

    Share, David L.; Jorm, Anthony F.; Maclean, Rod; Matthews, Russell

    2002-01-01

    Examines the hypothesis that early auditory temporal processing deficits cause later specific reading disability by impairing phonological processing. Suggests that auditory temporal deficits in dyslexics may be associated with dysphasic-type symptoms observed by Tallal and her colleagues in specific language-impaired populations, but do not cause…

  16. Phase stable RF transport system

    DOEpatents

    Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.

    1992-01-01

    An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.

  17. Stable maps and Quot schemes

    NASA Astrophysics Data System (ADS)

    Popa, Mihnea; Roth, Mike

    2003-06-01

    In this paper we study the relationship between two different compactifications of the space of vector bundle quotients of an arbitrary vector bundle on a curve. One is Grothendieck's Quot scheme, while the other is a moduli space of stable maps to the relative Grassmannian. We establish an essentially optimal upper bound on the dimension of the two compactifications. Based on that, we prove that for an arbitrary vector bundle, the Quot schemes of quotients of large degree are irreducible and generically smooth. We precisely describe all the vector bundles for which the same thing holds in the case of the moduli spaces of stable maps. We show that there are in general no natural morphisms between the two compactifications. Finally, as an application, we obtain new cases of a conjecture on effective base point freeness for pluritheta linear series on moduli spaces of vector bundles.

  18. Treatment of stable angina pectoris.

    PubMed

    Palaniswamy, Chandrasekar; Aronow, Wilbert S

    2011-09-01

    Management of stable angina pectoris includes antianginal medications, medications to prevent progression of atherosclerosis, and aggressive treatment of causative risk factors. Antianginal medications commonly used include nitrates, beta-blockers, calcium channel blockers, and ranolazine. Antiplatelet agents, statins, and angiotensin-converting enzyme inhibitors are used in patients with these problems to prevent progression of atherosclerosis and/or premature cardiovascular death. Aggressive risk factor control with diet; exercise; treatment of diabetes, hypertension, and dyslipidemia; and strategies to stop smoking and reduce weight should be a part of treatment strategy in all patients. Patients with stable angina who have symptoms refractory to medical treatment usually require coronary angiography, followed by either percutaneous or surgical revascularization. Recent mechanical techniques for the treatment of refractory angina include transmyocardial laser revascularization, enhanced external counterpulsation, and spinal cord stimulation. PMID:20861717

  19. Effects of temporal fluctuations on mixing

    NASA Astrophysics Data System (ADS)

    Pool, Maria; Dentz, Marco; Post, Vincent E. A.; Simmons, Craig T.

    2016-04-01

    Mixing and dispersion in coastal aquifers are strongly influenced by periodic temporal flow fluctuations on multiple time-scales ranging from days (tides), seasons (pumping and recharge) to glacial cycles (regression and transgressions). Transient forcing effects lead to a complex space- ant time-dependent flow response which induces enhanced spreading and mixing of a dissolved substance. We study effective mixing and solute transport in temporally fluctuating one-dimensional flow for a stable stratification of two fluids of different density. We derive explicit expressions for the concentration distribution and variance to identify the controls and obtain realistic predictions of the coupling between mixing and oscillatory transient flow. We find that the magnitude of transient-driven mixing is mainly controlled by the hydraulic diffusivity, the period and the initial interface location. We also find a spatial dependence of the effective dispersion coefficient which at long times causes the concentration profile to become asymmetric. Sand column experiments under well-controlled laboratory conditions are presented to validate the theoretical effective model defined. The proposed formulation is found to provide very good predictions and correctly reproduces the experimental mixing dynamics.

  20. Phenology of stable fly (Diptera: Muscidae) larvae in round bale hay feeding sites in Eastern Nebraska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The temporal and spatial patterns of adult stable fly, Stomoxys calcitrans (L.), emergence from six sites where large round baled hay had been provided to pastured cattle as winter feed were studied using emergence traps. The substrate at these sites, consisting of waste hay mixed with bovine manure...

  1. Stable fly phenology in a mixed agricultural-wildlife ecosystem in northeast Montana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable fly phenology was monitored and compared at three habitats (peninsula, pasture, confinement lot) located within 1.5 to 4.5 km of each other in a mixed agricultural-wildlife ecosystem in northeast Montana. Results revealed that temporal dynamics differed by site. Adult abundance was generall...

  2. Advanced Thermally Stable Jet Fuels

    SciTech Connect

    A. Boehman; C. Song; H. H. Schobert; M. M. Coleman; P. G. Hatcher; S. Eser

    1998-01-01

    The Penn State program in advanced thermally stable jet fuels has five components: 1) development of mechanisms of degradation and solids formation; 2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; 3) characterization of carbonaceous deposits by various instrumental and microscopic methods; 4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and 5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.

  3. LP based approach to optimal stable matchings

    SciTech Connect

    Teo, Chung-Piaw; Sethuraman, J.

    1997-06-01

    We study the classical stable marriage and stable roommates problems using a polyhedral approach. We propose a new LP formulation for the stable roommates problem. This formulation is non-empty if and only if the underlying roommates problem has a stable matching. Furthermore, for certain special weight functions on the edges, we construct a 2-approximation algorithm for the optimal stable roommates problem. Our technique uses a crucial geometry of the fractional solutions in this formulation. For the stable marriage problem, we show that a related geometry allows us to express any fractional solution in the stable marriage polytope as convex combination of stable marriage solutions. This leads to a genuinely simple proof of the integrality of the stable marriage polytope. Based on these ideas, we devise a heuristic to solve the optimal stable roommates problem. The heuristic combines the power of rounding and cutting-plane methods. We present some computational results based on preliminary implementations of this heuristic.

  4. Sensor-induced temporal variability of Landsat MSS data

    NASA Technical Reports Server (NTRS)

    Nelson, R. F.

    1985-01-01

    Landsat-1 and Landsat-2 multispectral scanner (MSS) data were studied to determine the consistency of the calculated reflectance values over time. Data from six spectrally stable targets were collected over a 3-year period (1975-1977). Reflectance values calculated from the digital numbers were regressed against time to note any long term changes. Results indicate that, over a 1000-day period beginning 1 January 1975, MSS 2 reflectances were stable. MSS 1 reflectances over that same period decreased approximately 25-32 percent. The observed decreases are most likely due to a deterioration of the transmissive qualities of the Landsat-1 scanner's internal optical path. Although MSS temporal variation may be unique to MSS 1, time (days in orbit) should be considered as an independent variable when intersatellite calibration equations are computed. A case is made for a stable, monitored calibration system which would permit the calculation of true top-of-the-atmosphere reflectance measures.

  5. Behavioral Changes Predicting Temporal Changes in Perceived Popular Status

    PubMed Central

    Bowker, Julie C.; Rubin, Kenneth H.; Buskirk-Cohen, Alison; Rose-Krasnor, Linda; Booth-LaForce, Cathryn

    2009-01-01

    The primary objectives of this investigation were to determine the extent to which young adolescents are stable in high perceived popular status across the middle school transition and to examine whether changes in social behaviors predict the stability, gain, and loss of perceived popular status after the transition. The sample included 672 young adolescents (323 boys) who completed peer-nomination assessments of social behavior and perceived popularity at the end of elementary school (5th grade) and the beginning of middle school (6th grade). Findings indicated that 62 percent of perceived popular adolescents remained stable in their high popular status across the middle school transition. Multinomial logistic regression analyses revealed that a combination of aggression and arrogance/conceit was associated with stable and newly-gained perceived popular status after the middle school transition. Taken together, findings highlight the significance of contextual and temporal changes in adolescents’ perceived popular status. PMID:20209113

  6. Temporal spike pattern learning

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

  7. Temporal spike pattern learning.

    PubMed

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

    2008-09-01

    Sensory systems pass information about an animal's environment to higher nervous system units through sequences of action potentials. When these action potentials have essentially equivalent wave forms, all information is contained in the interspike intervals (ISIs) of the spike sequence. How do neural circuits recognize and read these ISI sequences? We address this issue of temporal sequence learning by a neuronal system utilizing spike timing dependent plasticity (STDP). We present a general architecture of neural circuitry that can perform the task of ISI recognition. The essential ingredients of this neural circuit, which we refer to as "interspike interval recognition unit" (IRU) are (i) a spike selection unit, the function of which is to selectively distribute input spikes to downstream IRU circuitry; (ii) a time-delay unit that can be tuned by STDP; and (iii) a detection unit, which is the output of the IRU and a spike from which indicates successful ISI recognition by the IRU. We present two distinct configurations for the time-delay circuit within the IRU using excitatory and inhibitory synapses, respectively, to produce a delayed output spike at time t_{0}+tau(R) in response to the input spike received at time t_{0} . R is the tunable parameter of the time-delay circuit that controls the timing of the delayed output spike. We discuss the forms of STDP rules for excitatory and inhibitory synapses, respectively, that allow for modulation of R for the IRU to perform its task of ISI recognition. We then present two specific implementations for the IRU circuitry, derived from the general architecture that can both learn the ISIs of a training sequence and then recognize the same ISI sequence when it is presented on subsequent occasions. PMID:18851076

  8. Ancestry, Temporality, and Potentiality

    PubMed Central

    Gibbon, Sahra

    2014-01-01

    In this paper I examine the variety of ways potential is articulated, entailed, and produced in how the field of cancer genetics is being constituted as a domain of transnational research and an emerging site of health-care intervention in southern Brazil. Drawing on analysis of fieldwork in Brazilian cancer-genetics clinics, I explore how different expressions of potential come to inform dynamically the pursuit of prevention, care, and research as diversely scaled investments for those working and living with cancer-genetics knowledge and technologies. It illustrates how specific temporalities help to constitute and “abductively” frame the meaning of these different potentials particularly as this relates to a focus on ancestry. Colonial histories of migration, the embodied effects of dietary habits, or the moral failings of near and distant ancestors as well as promissory futures and the contingency of lived lives become at different times templates for identifying, materializing, and transforming how the potential of cancer genetics in Brazil is articulated. Potential is also expressed through an idiom of “choice” in different efforts to situate participation in cancer-genetics research as prevention or to negotiate access to basic public health. I explore how these expressions of cancer genetics as potential powerfully yet unevenly work to sustain knowledge practices as well as propel patients and their families into fledgling domains of clinical practice and scientific research. At the same time there is always an “excess of meaning” in these endeavors that make visible lines of fracture and disjuncture in collective efforts to make future histories of and from the pursuit of cancer genetics in southern Brazil. PMID:25018561

  9. Ultra-stable oscillator with complementary transistors

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (Inventor)

    1974-01-01

    A high frequency oscillator, having both good short and long term stability, is formed by including a piezoelectric crystal in the base circuit of a first bi-polar transistor circuit, the bi-polar transistor itself operated below its transitional frequency and having its emitter load chosen so that the input impedance, looking into the base thereof, exhibits a negative resistance in parallel with a capacitive reactance. Combined with this basic circuit is an auxiliary, complementary, second bi-polar transistor circuit of the same form with the piezoelectric crystal being common to both circuits. By this configuration small changes in quiescent current are substantially cancelled by opposite variations in the second bi-polar transistor circuit, thereby achieving from the oscillator a signal having its frequency of oscillation stable over long time periods as well as short time periods.

  10. Stable isotope investigations of chlorinated aliphatic hydrocarbons.

    SciTech Connect

    Abrajano, T.; Heraty, L. J.; Holt, B. D.; Huang, L.; Sturchio, N. C.

    1999-06-01

    Stable isotope ratio measurements for carbon (C) and chlorine (Cl) can be used to elucidate the processes affecting transformation and transportation of chlorinated aliphatic hydrocarbons (CAHs) in the environment. Methods recently developed in our laboratory for isotopic analysis of CAHs have been applied to laboratory measurements of the kinetic isotope effects associated with aerobic degradation of dichloromethane (DCM) and with both anaerobic and aerobic cometabolic degradation of trichlomethene (TCE) in batch and column microbial cultures. These experimental determinations of fractionation factors are crucial for understanding the behavior of CAHs in complex natural systems, where the extent of biotransformation can be masked by dispersion and volatilization. We have also performed laboratory investigations of kinetic isotope effects accompanying evaporation of CAHs, as well as field investigations of natural attenuation and in situ remediation of CAHs in a number of contaminated shallow aquifers at sites operated by the federal government and the private sector.

  11. Polarization temporal dynamics in a dye microlaser

    SciTech Connect

    Aiello, A.; De Martini, F.; Mataloni, P.

    1996-01-01

    We have investigated the temporal dynamics of the output polarization of a dye microlaser operating in a transient regime, i.e., under femtosecond excitation. In these conditions the dipole angular diffusion has an important role in the formation of the microlaser pulse, as is shown in a theoretical model. By performing the experiment for different values of the microcavity length and varying the polarization angle, we measured threshold and buildup time of the microlaser and compared the results obtained with two dye solutions of different viscosity. The agreement between theory and experimental results is adequate. {copyright} {ital 1996 Optical Society of America.}

  12. Tungsten Stable Isotope Compositions of Ferromanganese Crusts

    NASA Astrophysics Data System (ADS)

    Abraham, K.; Barling, J.; Hein, J. R.; Schauble, E. A.; Halliday, A. N.

    2014-12-01

    We report the first accurate and precise data for mass-dependent fractionation of tungsten (W) stable isotopes, using a double spike technique and MC-ICPMS. Results are expressed relative to the NIST 3136 W isotope standard as per mil deviations in 186W/184W (δ186W). Although heavy element mass-dependent fractionations are expected to be small, Tl and U both display significant low temperature isotopic fractionations. Theoretical calculations indicate that W nuclear volume isotopic effects should be smaller than mass-dependent fractionations at low temperatures. Hydrogenetic ferromanganese (Fe-Mn) crusts precipitate directly from seawater and have been used as paleoceanographic recorders of temporal changes in seawater chemistry. Crusts are strongly enriched in W and other metals, and are a promising medium for exploring W isotopic variability. Tungsten has a relatively long residence time in seawater of ~61,000 years, mainly as the tungstate ion (WO42-). Water depth profiles show conservative behaviour. During adsorption on Fe-Mn crusts, W species form inner-sphere complexes in the hexavalent (W6+) state. The major host phase is thought to be Mn oxides and the lighter W isotope is expected to be absorbed preferentially. Surface scrapings of 13 globally distributed hydrogenetic Fe-Mn crusts display δ186W from -0.08 to -0.22‰ (±0.03‰, 2sd). A trend toward lighter W isotope composition exists with increasing water depth (~1500 to ~5200m) and W concentration. One hydrothermal Mn-oxide sample is anomalously light and Mn nodules are both heavy and light relative to Fe-Mn crusts. Tungsten speciation depends on concentration, pH, and time in solution and is not well understood because of the extremely slow kinetics of the reactions. In addition, speciation of aqueous and/or adsorbed species might be sensitive to pressure, showing similar thermodynamic stability but different effective volumes. Thus, W stable isotopes might be used as a water-depth barometer in

  13. Temporal and structural heterogeneities emerging in adaptive temporal networks

    NASA Astrophysics Data System (ADS)

    Aoki, Takaaki; Rocha, Luis E. C.; Gross, Thilo

    2016-04-01

    We introduce a model of adaptive temporal networks whose evolution is regulated by an interplay between node activity and dynamic exchange of information through links. We study the model by using a master equation approach. Starting from a homogeneous initial configuration, we show that temporal and structural heterogeneities, characteristic of real-world networks, spontaneously emerge. This theoretically tractable model thus contributes to the understanding of the dynamics of human activity and interaction networks.

  14. Longitudinal progression of frontal and temporal lobe changes in schizophrenia.

    PubMed

    Cobia, Derin J; Smith, Matthew J; Wang, Lei; Csernansky, John G

    2012-08-01

    Cortical abnormalities are considered a neurobiological characteristic of schizophrenia. However, the pattern of such deficits as they progress over the illness remains poorly understood. The goal of this project was to assess the progression of cortical thinning in frontal and temporal cortical regions in schizophrenia, and determine whether relationships exist between them and neuropsychological and clinical symptom profiles. As part of a larger longitudinal 2-year follow-up study, schizophrenia (n=20) and healthy participants (n=20) group-matched for age, gender, and recent-alcohol use, were selected. Using MRI, estimates of gray matter thickness were derived from primary anatomical gyri of the frontal and temporal lobes using surface-based algorithms. These values were entered into repeated-measures analysis of variance models to determine group status and time effects. Change values in cortical regions were correlated with changes in neuropsychological functioning and clinical symptomatology. Results revealed exaggerated cortical thinning of the middle frontal, superior temporal, and middle temporal gyri in schizophrenia participants. These thickness changes strongly influenced volumetric reductions, but were not related to shrinking surface area. Neuropsychological and clinical symptom profiles were stable in the schizophrenia participants despite these neuroanatomic changes. Overall it appears that ongoing abnormalities in the cerebral cortex continue after initial onset of schizophrenia, particularly the lateral aspects of frontal and temporal regions, and do not relate to neuropsychological or clinical measures over time. Maintenance of neuropsychological performance and clinical stability in the face of changing neuroanatomical structure suggests the involvement of alternative compensatory mechanisms. PMID:22647883

  15. Stable Hemiaminals: 2-Aminopyrimidine Derivatives.

    PubMed

    Kwiecień, Anna; Ciunik, Zbigniew

    2015-01-01

    Stable hemiaminals can be obtained in the one-pot reaction between 2-aminopyrimidine and nitrobenzaldehyde derivatives. Ten new hemiaminals have been obtained, six of them in crystal state. The molecular stability of these intermediates results from the presence of both electron-withdrawing nitro groups as substituents on the phenyl ring and pyrimidine ring, so no further stabilisation by intramolecular interaction is required. Hemiaminal molecules possess a tetrahedral carbon atom constituting a stereogenic centre. As the result of crystallisation in centrosymmetric space groups both enantiomers are present in the crystal structure. PMID:26258772

  16. Staff detection with stable paths.

    PubMed

    Dos Santos Cardoso, Jaime; Capela, Artur; Rebelo, Ana; Guedes, Carlos; Pinto da Costa, Joaquim

    2009-06-01

    The preservation of musical works produced in the past requires their digitalization and transformation into a machine-readable format. The processing of handwritten musical scores by computers remains far from ideal. One of the fundamental stages to carry out this task is the staff line detection. We investigate a general-purpose, knowledge-free method for the automatic detection of music staff lines based on a stable path approach. Lines affected by curvature, discontinuities, and inclination are robustly detected. Experimental results show that the proposed technique consistently outperforms well-established algorithms. PMID:19372615

  17. Organic Mood Disorder Following Left Anterior Temporal Lobectomy with Amygdalohippocampectomy.

    PubMed

    Haridas, Nishanth J; Kalayil, Rajeesh V; Tharayil, Harish M; Rappai, Mary P

    2015-01-01

    One third of patients with antiepileptic-resistant temporal lobe epilepsy (TLE) will have to undergo surgery for a better seizure control. Anterior temporal lobectomy (ATL) is done for mesial temporal sclerosis that is the most common histopathological lesion associated with TLE. Psychiatric manifestations following ATL are not uncommon with depressive symptoms more common with left ATL and manic symptoms following right ATL. Mr. A is a 42-year-old left cerebral dominant (Confirmed by WADA test) male with no past history of psychiatric illness who had undergone anterior temporal lobectomy with amygdalohippocampectomy. He started having manic episodes post operatively which subsided with antipsychotics. He had multiple such episodes over the next 13 years with minimal inter episodic symptoms. This is a rare instance of manic symptoms following left-sided ATL that emphasizes the need for better understanding of the cerebral laterality of affective symptoms. PMID:26702178

  18. Biocybernetic system evaluates indices of operator engagement in automated task

    NASA Technical Reports Server (NTRS)

    Pope, A. T.; Bogart, E. H.; Bartolome, D. S.

    1995-01-01

    A biocybernetic system has been developed as a method to evaluate automated flight deck concepts for compatibility with human capabilities. A biocybernetic loop is formed by adjusting the mode of operation of a task set (e.g., manual/automated mix) based on electroencephalographic (EEG) signals reflecting an operator's engagement in the task set. A critical issue for the loop operation is the selection of features of the EEG to provide an index of engagement upon which to base decisions to adjust task mode. Subjects were run in the closed-loop feedback configuration under four candidate and three experimental control definitions of an engagement index. The temporal patterning of system mode switching was observed for both positive and negative feedback of the index. The indices were judged on the basis of their relative strength in exhibiting expected feedback control system phenomena (stable operation under negative feedback and unstable operation under positive feedback). Of the candidate indices evaluated in this study, an index constructed according to the formula, beta power/(alpha power + theta power), reflected task engagement best.

  19. Interpreting bryophyte stable carbon isotope composition: Plants as temporal and spatial climate recorders

    NASA Astrophysics Data System (ADS)

    Royles, Jessica; Horwath, Aline B.; Griffiths, Howard

    2014-04-01

    are unable to control tissue water content although physiological adaptations allow growth in a wide range of habitats. Carbon isotope signals in two mosses (Syntrichia ruralis and Chorisodontium aciphyllum) and two liverworts (Conocephalum conicum and Marchantia polymorpha), whether instantaneous (real time, Δ13C), or organic matter (as δ13COM), provide an assimilation-weighted summary of bryophyte environmental adaptations. In mosses, δ13COM is within the measured range of Δ13C values, which suggests that other proxies, such as compound-specific organic signals, will be representative of historical photosynthetic and growth conditions. The liverworts were photosynthetically active over a wider range of relative water contents (RWC) than the mosses. There was a consistent 5‰ offset between Δ13C values in C. conicum and M. polymorpha, suggestive of greater diffusion limitation in the latter. Analysis of a C. aciphyllum moss-peat core showed the isotopic composition over the past 200 years reflects recent anthropogenic CO2 emissions. Once corrected for source-CO2 inputs, the seasonally integrated Δ13COM between 1350 and 2000 A.D. varied by 1.5‰ compared with potential range of the 12‰ measured experimentally, demonstrating the relatively narrow range of conditions under which the majority of net assimilation takes place. Carbon isotope discrimination also varies spatially, with a 4‰ shift in epiphytic bryophyte organic matter found between lowland Amazonia and upper montane tropical cloud forest in the Peruvian Andes, associated with increased diffusion limitation.

  20. Optical communications: Temporal ghost imaging

    NASA Astrophysics Data System (ADS)

    Faccio, Daniele

    2016-03-01

    Ghost imaging allows the creation of images using light that never interacts with the object. Researchers now show that this technique can be applied to reconstruct temporal 'images' of rapidly varying, picosecond signals in telecommunication systems.

  1. Persistence Length of Stable Microtubules

    NASA Astrophysics Data System (ADS)

    Hawkins, Taviare; Mirigian, Matthew; Yasar, M. Selcuk; Ross, Jennifer

    2011-03-01

    Microtubules are a vital component of the cytoskeleton. As the most rigid of the cytoskeleton filaments, they give shape and support to the cell. They are also essential for intracellular traffic by providing the roadways onto which organelles are transported, and they are required to reorganize during cellular division. To perform its function in the cell, the microtubule must be rigid yet dynamic. We are interested in how the mechanical properties of stable microtubules change over time. Some ``stable'' microtubules of the cell are recycled after days, such as in the axons of neurons or the cilia and flagella. We measured the persistence length of freely fluctuating taxol-stabilized microtubules over the span of a week and analyzed them via Fourier decomposition. As measured on a daily basis, the persistence length is independent of the contour length. Although measured over the span of the week, the accuracy of the measurement and the persistence length varies. We also studied how fluorescently-labeling the microtubule affects the persistence length and observed that a higher labeling ratio corresponded to greater flexibility. National Science Foundation Grant No: 0928540 to JLR.

  2. Neuropathology of Temporal Lobe Epilepsy

    PubMed Central

    Al Sufiani, Fahd; Ang, Lee Cyn

    2012-01-01

    Pathologic findings in surgical resections from patients with temporal lobe epilepsy include a wide range of diagnostic possibilities that can be categorized into different groups on the basis of etiology. This paper outlines the various pathologic entities described in temporal lobe epilepsy, including some newly recognized epilepsy-associated tumors, and briefly touch on the recent classification of focal cortical dysplasia. This classification takes into account coexistent pathologic lesions in focal cortical dysplasia. PMID:22957233

  3. Decision processes in temporal discrimination.

    PubMed

    Balcı, Fuat; Simen, Patrick

    2014-06-01

    The processing dynamics underlying temporal decisions and the response times they generate have received little attention in the study of interval timing. In contrast, models of other simple forms of decision making have been extensively investigated using response times, leading to a substantial disconnect between temporal and non-temporal decision theories. An overarching decision-theoretic framework that encompasses existing, non-temporal decision models may, however, account both for interval timing itself and for time-based decision-making. We sought evidence for this framework in the temporal discrimination performance of humans tested on the temporal bisection task. In this task, participants retrospectively categorized experienced stimulus durations as short or long based on their perceived similarity to two, remembered reference durations and were rewarded only for correct categorization of these references. Our analysis of choice proportions and response times suggests that a two-stage, sequential diffusion process, parameterized to maximize earned rewards, can account for salient patterns of bisection performance. The first diffusion stage times intervals by accumulating an endogenously noisy clock signal; the second stage makes decisions about the first-stage temporal representation by accumulating first-stage evidence corrupted by endogenous noise. Reward-maximization requires that the second-stage accumulation rate and starting point be based on the state of the first-stage timer at the end of the stimulus duration, and that estimates of non-decision-related delays should decrease as a function of stimulus duration. Results are in accord with these predictions and thus support an extension of the drift-diffusion model of static decision making to the domain of interval timing and temporal decisions. PMID:24726447

  4. The grounding of temporal metaphors.

    PubMed

    Lai, Vicky T; Desai, Rutvik H

    2016-03-01

    Grounded cognition suggests that the processing of conceptual knowledge cued by language relies on the sensory-motor regions. Does temporal language similarly engage brain areas involved in time perception? Participants read sentences that describe the temporal extent of events with motion verbs (The hours crawled until the release of the news) and their static controls. Comparison conditions were fictive motion (The trail crawled until the end of the hills) and literal motion (The caterpillar crawled towards the top of the tree), along with their static controls. Several time sensitive locations, identified using a meta-analysis, showed activation specific to temporal metaphors, including in the left insula, right claustrum, and bilateral posterior superior temporal sulci. Fictive and literal motion contrasts did not show this difference. Fictive motion contrast showed activation in a conceptual motion sensitive area of the left posterior inferior temporal sulcus (ITS). These data suggest that language of time is at least partially grounded in experiential time. In addition, motion semantics has different consequences for events and objects: temporal events become animate, while static entities become motional. PMID:26854961

  5. Stereopsis after anterior temporal lobectomy.

    PubMed

    Verhoef, Bram-Ernst; Decramer, Thomas; van Loon, Johannes; Goffin, Jan; Van Paesschen, Wim; Janssen, Peter; Theys, Tom

    2016-09-01

    Brain areas critical for stereopsis have been investigated in non-human primates but are largely unknown in the human brain. Microelectrode recordings and functional MRI (fMRI) studies in monkeys have shown that in monkeys the inferior temporal cortex is critically involved in 3D shape categorization. Furthermore, some human fMRI studies similarly suggest an involvement of visual areas in the temporal lobe in depth perception. We aimed to investigate the role of the human anterior temporal neocortex in stereopsis by assessing stereoscopic depth perception before and after anterior temporal lobectomy. Eighteen epilepsy surgery patients were tested, pre- and postoperatively, in 3 different depth discrimination tasks. Sensitivity for local and global disparity was tested in a near-far discrimination task and sensitivity for 3D curvature was assessed in a convex-concave discrimination task, where 3D shapes were presented at different positions in depth. We found no evidence that temporal lobe epilepsy surgery has a significant effect on stereopsis. In contrast with earlier findings, we conclude that local as well as global stereopsis is maintained after unilateral resection of the temporal pole in epilepsy surgery patients. Our findings, together with previous studies, suggest that in humans more posterior visual regions underlie depth perception. PMID:27344239

  6. Working with Spatio-Temporal Data Type

    NASA Astrophysics Data System (ADS)

    Raza, A.

    2012-07-01

    Several aspects of spatiotemporal databases have been explored in past decades, ranging from basic data structure to query processing and indexing. But today, operational temporal GIS does not exist. The key impediments have been the complexity of integrating space and time and the lack of standards. OpenGIS standards for simple feature access (spatial type) do exist, but unlike the spatial type, standards for spatiotemporal data type do not exist. This paper explores a new approach to modeling space and time to provide the basis for implementing a temporal GIS. This approach is based on the concept of data types in databases. A data type provides constructors, accessors, and operators. Most commercial and open source databases provide data types to deal with the spatial component of a GIS, called spatial type. Oracle Spatial, DB2 Spatial Extender and Informix Spatial DataBlade, ST_Geometry for PostgreSQL and Oracle from Esri, PostGIS for PostgreSQL, etc., are some examples. This new spatiotemporal data type is called spatiotemporal type (STT). This STT is implemented in PostgreSQL, an open source relational database management system. The STT is an extension of Esri's ST_Geometry type for PostgreSQL, in which each spatial object has a life span. Constructors, accessors, and relational functions are provided to create STT and support spatial, spatiotemporal, and temporal queries. Some functions are extended based on OpenGIS standards for the spatial type. Examples are provided to demonstrate the application of these functions. The paper concludes with limitations and challenges of implementing STT.

  7. Mixture of Skewed α-Stable Distributions

    NASA Astrophysics Data System (ADS)

    Shojaei, S. R. Hosseini; Nassiri, V.; Mohammadian, Gh. R.; Mohammadpour, A.

    2011-03-01

    Expectation maximization (EM) algorithm and the Bayesian techniques are two approaches for statistical inference of mixture models [3, 4]. By noting the advantages of the Bayesian methods, practitioners prefer them. However, implementing Markov chain Monte Carlo algorithms can be very complicated for stable distributions, due to the non-analytic density or distribution function formulas. In this paper, we introduce a new class of mixture of heavy-tailed distributions, called mixture of skewed stable distributions. Skewed stable distributions belongs to the exponential family and they have analytic density representation. It is shown that skewed stable distributions dominate skew stable distribution functions and they can be used to model heavy-tailed data. The class of skewed stable distributions has an analytic representation for its density function and the Bayesian inference can be done similar to the exponential family of distributions. Finally, mixture of skewed stable distributions are compared to the mixture of stable distributions through a simulations study.

  8. A possible mechanism of interleaving at weak baroclinic fronts under stable-stable stratification in the Arctic Basin

    NASA Astrophysics Data System (ADS)

    Kuzmina, Natalia; Izvekova, Yulia N.

    2016-04-01

    Some analytical solutions are found for the problem of three-dimensional instability of a weak geostrophic flow with linear velocity shear taking into account vertical diffusion of buoyancy. The analysis is based on the potential vorticity equation in a long-wave approximation when the horizontal scale of disturbances is taken much larger than the local baroclinic radius Rossby. It is hypothesized that the solutions found can be applied to describe stable and unstable disturbances of planetary scale with respect, especially, to the Arctic basin where weak baroclinic fronts with typical temporal variability period of the order of several years or more are observed and the beta-effect is negligible. Stable (decreasing with time) solutions describe disturbances that, in contrast to the Rossby waves, can propagate both to the west and east depending on the sign of linear shear of geostrophic velocity. The unstable (growing with time) solutions are applied to describe large-scale intrusions at baroclinic fronts under stable-stable thermohaline stratification observed in the upper layer of the Polar Deep Water in the Eurasian basin. The proposed description of intrusive layering can be considered as a possible alternative to the mechanism of interleaving due to the differential mixing (Merryfield, 2002; Kuzmina et al., 2011). References Kuzmina N., Rudels B., Zhurbas V., Stipa T. On the structure and dynamical features of intrusive layering in the Eurasian Basin in the Arctic Ocean. J. Geophys. Res., 2011, 116, C00D11, doi:10.1029/2010JC006920. Merryfield W. J. Intrusions in double-diffusively stable Arctic Waters: Evidence for differential mixing? J. Phys. Oceanogr., 2002, 32, 1452-1439.

  9. Temporal stability of electrical conductivity in a sandy soil

    NASA Astrophysics Data System (ADS)

    Pedrera-Parrilla, Aura; Brevik, Eric C.; Giráldez, Juan V.; Vanderlinden, Karl

    2016-07-01

    Understanding of soil spatial variability is needed to delimit areas for precision agriculture. Electromagnetic induction sensors which measure the soil apparent electrical conductivity reflect soil spatial variability. The objectives of this work were to see if a temporally stable component could be found in electrical conductivity, and to see if temporal stability information acquired from several electrical conductivity surveys could be used to better interpret the results of concurrent surveys of electrical conductivity and soil water content. The experimental work was performed in a commercial rainfed olive grove of 6.7 ha in the `La Manga' catchment in SW Spain. Several soil surveys provided gravimetric soil water content and electrical conductivity data. Soil electrical conductivity values were used to spatially delimit three areas in the grove, based on the first principal component, which represented the time-stable dominant spatial electrical conductivity pattern and explained 86% of the total electrical conductivity variance. Significant differences in clay, stone and soil water contents were detected between the three areas. Relationships between electrical conductivity and soil water content were modelled with an exponential model. Parameters from the model showed a strong effect of the first principal component on the relationship between soil water content and electrical conductivity. Overall temporal stability of electrical conductivity reflects soil properties and manifests itself in spatial patterns of soil water content.

  10. Results of the Stable Microgravity Vibration Isolation Flight Experiment

    NASA Technical Reports Server (NTRS)

    Edberg, Donald; Boucher, Robert; Schenck, David; Nurre, Gerald; Whorton, Mark; Kim, Young; Alhorn, Dean

    1996-01-01

    This paper presents an overview of the STABLE microgravity isolation system developed and successfully flight tested in October 1995. A description of the hardware design and operational principles is given. A sample of the measured flight data is presented, including an evaluation of attenuation performance provided by the actively controlled electromagnetic isolation system. Preliminary analyses of flight data show that the acceleration environment aboard STABLE's isolated platform was attenuated by a factor of more than 25 between 0.1 and 100 Hz. STABLE was developed under a cooperative agreement between National Aeronautics and Space Administration, Marshall Space Flight Center, and McDonnell Douglas Aerospace. The flight hardware was designed, fabricated, integrated, tested, and delivered to the Cape during a five month period.

  11. Stable density stratification solar pond

    NASA Technical Reports Server (NTRS)

    Lansing, F. L. (Inventor)

    1985-01-01

    A stable density-stratification solar pond for use in the collection and storage of solar thermal energy including a container having a first section characterized by an internal wall of a substantially cylindrical configuration and a second section having an internal wall of a substantially truncated conical configuration surmounting the first section in coaxial alignment therewith, the second section of said container being characterized by a base of a diameter substantially equal to the diameter of the first section and a truncated apex defining a solar energy acceptance opening is discussed. A body of immiscible liquids is disposed within the container and comprises a lower portion substantially filling the first section of the container and an upper portion substantially filling the second section of the container, said lower portion being an aqueous based liquid of a darker color than the upper portion and of a greater density. A protective cover plate is removably provided for covering the acceptance opening.

  12. Stable massive particles at colliders

    SciTech Connect

    Fairbairn, M.; Kraan, A.C.; Milstead, D.A.; Sjostrand, T.; Skands, P.; Sloan, T.; /Lancaster U.

    2006-11-01

    We review the theoretical motivations and experimental status of searches for stable massive particles (SMPs) which could be sufficiently long-lived as to be directly detected at collider experiments. The discovery of such particles would address a number of important questions in modern physics including the origin and composition of dark matter in the universe and the unification of the fundamental forces. This review describes the techniques used in SMP-searches at collider experiments and the limits so far obtained on the production of SMPs which possess various colour, electric and magnetic charge quantum numbers. We also describe theoretical scenarios which predict SMPs, the phenomenology needed to model their production at colliders and interactions with matter. In addition, the interplay between collider searches and open questions in cosmology such as dark matter composition are addressed.

  13. Dimensionally stable metallic hydride composition

    DOEpatents

    Heung, Leung K.

    1994-01-01

    A stable, metallic hydride composition and a process for making such a composition. The composition comprises a uniformly blended mixture of a metal hydride, kieselguhr, and a ballast metal, all in the form of particles. The composition is made by subjecting a metal hydride to one or more hydrogen absorption/desorption cycles to disintegrate the hydride particles to less than approximately 100 microns in size. The particles are partly oxidized, then blended with the ballast metal and the kieselguhr to form a uniform mixture. The mixture is compressed into pellets and calcined. Preferably, the mixture includes approximately 10 vol. % or more kieselguhr and approximately 50 vol. % or more ballast. Metal hydrides that can be used in the composition include Zr, Ti, V, Nb, Pd, as well as binary, tertiary, and more complex alloys of La, Al, Cu, Ti, Co, Ni, Fe, Zr, Mg, Ca, Mn, and mixtures and other combinations thereof. Ballast metals include Al, Cu and Ni.

  14. Sugar feeding in adult stable flies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adult stable flies, (Stomoxys calcitrans (L.)), are known to feed readily on sugars in the laboratory. However, little is known concerning the extent of stable fly sugar feeding in wild populations. We examined the frequency of sugar feeding in stable flies in rural and urban environments. In additi...

  15. Uses of stable isotopes in fish ecology

    EPA Science Inventory

    Analyses of fish tissues (other than otoliths) for stable isotope ratios can provide substantial information on fish ecology, including physiological ecology. Stable isotopes of nitrogen and carbon frequently are used to determine the mix of diet sources for consumers. Stable i...

  16. Stable line defects in silicene

    NASA Astrophysics Data System (ADS)

    Ghosh, Dibyajyoti; Parida, Prakash; Pati, Swapan K.

    2015-11-01

    Line defects in two-dimensional (2D) materials greatly modulate various properties of their pristine form. Using ab initio molecular dynamics (AIMD) simulations, we investigate the structural reconstructions of different kinds of grain boundaries in the silicene sheets. It is evident that depending upon the presence of silicon adatoms and edge shape of grain boundaries (i.e., armchair or zigzag), stable extended line defects (ELDs) can be introduced in a controlled way. Further studies show the stability of these line-defects in silicene, grown on Ag(111) surface at room-temperature. Importantly, unlike most of the 2D sheet materials such as graphene and hexagonal boron nitride, 5-5-8 line defects modify the nonmagnetic semimetallic pristine silicene sheet to spin-polarized metal. As ferromagnetically ordered magnetic moments remain strongly localized at the line defect, a one-dimensional spin channel gets created in silicene. Interestingly, these spin channels are quite stable because, unlike the edge of nanoribbons, structural reconstruction or contamination cannot destroy the ordering of magnetic moments here. Zigzag silicene nanoribbons with a 5-5-8 line defect also exhibit various interesting electronic and magnetic properties depending upon their width as well as the nature of the magnetic coupling between edge and defect spin states. Upon incorporation of other ELDs, such as 4-4-4 and 4-8 defects, 2D sheets and nanoribbons of silicene show a nonmagnetic metallic or semiconducting ground state. Highlighting the controlled formation of ELDs and consequent emergence of technologically important properties in silicene, we propose new routes to realize silicene-based nanoelectronic and spintronic devices.

  17. New Proxy for Recent Hurricane Events Using Stalagmite Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Frappier, A.; Sahagian, D.

    2002-12-01

    Using recently developed micro-sampling techniques for stable isotope analyses, we obtained monthly to weekly temporal resolution in a fast growing stalagmite from Belize that recorded the last 3 decades of carbonate deposition. The stable oxygen isotope record (O-18 values) varies at interannual to sub-seasonal scales. The largest variations in O-18 values are interannual (corresponding to El Nino events) and annual (corresponding to the strong wet-dry seasonality of the region). Smaller amplitude O-18 variations related to short-term weather fluctuations are also apparent. Brief, low excursions in O-18 values can be identified with hurricane events that impacted Belize in recent decades. This dataset demonstrates that at least some stalagmites can record measurable, low stable oxygen isotope excursions from individual hurricane rainfall events. The proxy is sensitive to storm intensity and distance of storm track to the cave site. This paleotempestology proxy allows estimates of individual storm rainfall amounts and recurrence interval. Pre-historic hurricane events should be detectable using this technique; however, cave sites and individual stalagmites must be selected carefully to recover samples with measurable hurricane records.

  18. Turbulence Spreading into Linearly Stable Zone and Transport Scaling

    SciTech Connect

    T.S. Hahm; P.H. Diamond; Z. Lin; K. Itoh; S.-I. Itoh

    2003-10-20

    We study the simplest problem of turbulence spreading corresponding to the spatio-temporal propagation of a patch of turbulence from a region where it is locally excited to a region of weaker excitation, or even local damping. A single model equation for the local turbulence intensity I(x, t) includes the effects of local linear growth and damping, spatially local nonlinear coupling to dissipation and spatial scattering of turbulence energy induced by nonlinear coupling. In the absence of dissipation, the front propagation into the linearly stable zone occurs with the property of rapid progression at small t, followed by slower subdiffusive progression at late times. The turbulence radial spreading into the linearly stable zone reduces the turbulent intensity in the linearly unstable zone, and introduces an additional dependence on the rho* is always equal to rho i/a to the turbulent intensity and the transport scaling. These are in broad, semi-quantitative agreements with a number of global gyrokinetic simulation results with zonal flows and without zonal flows. The front propagation stops when the radial flux of fluctuation energy from the linearly unstable region is balanced by local dissipation in the linearly stable region.

  19. Effects of Temporal Context and Temporal Expectancy on Neural Activity in Inferior Temporal Cortex

    PubMed Central

    Anderson, Britt; Sheinberg, David L.

    2008-01-01

    Timing is critical. The same event can mean different things at different times and some events are more likely to occur at one time than another. We used a cued visual classification task to evaluate how changes in temporal context affect neural responses in inferior temporal cortex, an extrastriate visual area known to be involved in object processing. On each trial a first image cued a temporal delay before a second target image appeared. The animal’s task was to classify the second image by pressing one of two buttons previously associated with that target. All images were used as both cues and targets. Whether an image cued a delay time or signaled a button press depended entirely upon whether it was the first or second picture in a trial. This paradigm allowed us to compare inferior temporal cortex neural activity to the same image subdivided by temporal context and expectation. Neuronal spiking was more robust and visually evoked local field potentials (LFP’s) larger for target presentations than for cue presentations. On invalidly cued trials, when targets appeared unexpectedly early, the magnitude of the evoked LFP was reduced and delayed and neuronal spiking was attenuated. Spike field coherence increased in the beta-gamma frequency range for expected targets. In conclusion, different neural responses in higher order ventral visual cortex may occur for the same visual image based on manipulations of temporal attention. PMID:18206961

  20. Brain Regions Underlying Word Finding Difficulties in Temporal Lobe Epilepsy

    ERIC Educational Resources Information Center

    Trebuchon-Da Fonseca, Agnes; Guedj, Eric; Alario, F-Xavier; Laguitton, Virginie; Mundler, Olivier; Chauvel, Patrick; Liegeois-Chauvel, Catherine

    2009-01-01

    Word finding difficulties are often reported by epileptic patients with seizures originating from the language dominant cerebral hemisphere, for example, in temporal lobe epilepsy. Evidence regarding the brain regions underlying this deficit comes from studies of peri-operative electro-cortical stimulation, as well as post-surgical performance.…

  1. Temporal Factors of the Rorschach White Space Response.

    ERIC Educational Resources Information Center

    Carlson, Roy W.; Morris, Gary W.

    1980-01-01

    The claim by Bandura that the Rorschach space response is an artifact of longer blot exposure is questioned because of failure to account for the relationship between productivity and space response rates. Results of this study indicate that no significant temporal effect operates on space response rate. (Author/BEF)

  2. Stable CSR in storage rings: A model

    SciTech Connect

    Sannibale, Fernando; Byrd, John M.; Loftsdottir, Agusta; Venturini, Marco; Abo-Bakr, Michael; Feikes, Jorge; Holldack, Karsten; Kuske, Peter; Wustefeld, Godehart; Hubers, Heinz-Willerm; Warnock, Robert

    2005-01-03

    A comprehensive historical view of the work done on coherent synchrotron radiation (CSR) in storage rings is given in reference [1]. Here we want just to point out that even if the issue of CSR in storage rings was already discussed over 50 years ago, it is only recently that a considerable number of observations have been reported. In fact, intense bursts of coherent synchrotron radiation with a stochastic character were measured in the terahertz frequency range, at several synchrotron light source storage rings [2-8]. It has been shown [8-11], that this bursting emission of CSR is associated with a single bunch instability, usually referred as microbunching instability (MBI), driven by the fields of the synchrotron radiation emitted by the bunch itself. Of remarkably different characteristics was the CSR emission observed at BESSY II in Berlin, when the storage ring was tuned into a special low momentum compaction mode [12, 13]. In fact, the emitted radiation was not the quasi-random bursting observed in the other machines, but a powerful and stable flux of broadband CSR in the terahertz range. This was an important result, because it experimentally demonstrated the concrete possibility of constructing a stable broadband source with extremely high power in the terahertz region. Since the publication of the first successful experiment using the ring as a CSR source [14], BESSY II has regular scheduled user s shifts dedicated to CSR experiments. At the present time, several other laboratories are investigating the possibility of a CSR mode of operation [15-17] and a design for a new ring optimized for CSR is at an advanced stage [18]. In what follows, we describe a model that first accounts for the BESSY II observations and then indicates that the special case of BESSY II is actually quite general and typical when relativistic electron storage rings are tuned for short bunches. The model provides a scheme for predicting and optimizing the performance of ring

  3. Monolithic amplifier with stable, high resistance feedback element and method for fabricating the same

    DOEpatents

    O`Connor, P.

    1998-08-11

    A monolithic amplifier includes a stable, high resistance feedback circuit and a dynamic bias circuit. The dynamic bias circuit is formed with active elements matched to those in the amplifier and feedback circuit to compensate for variations in the operating and threshold voltages thereby maintaining a stable resistance in the feedback circuit. 11 figs.

  4. Monolithic amplifier with stable, high resistance feedback element and method for fabricating the same

    DOEpatents

    O'Connor, Paul

    1998-08-11

    A monolithic amplifier includes a stable, high resistance feedback circuit and a dynamic bias circuit. The dynamic bias circuit is formed with active elements matched to those in the amplifier and feedback circuit to compensate for variations in the operating and threshold voltages thereby maintaining a stable resistance in the feedback circuit.

  5. Chaotic itinerancy, temporal segmentation and spatio-temporal combinatorial codes

    NASA Astrophysics Data System (ADS)

    Dias, Juliana R.; Oliveira, Rodrigo F.; Kinouchi, Osame

    2008-01-01

    We study a deterministic dynamics with two time scales in a continuous state attractor network. To the usual (fast) relaxation dynamics towards point attractors (“patterns”) we add a slow coupling dynamics that makes the visited patterns lose stability, leading to an itinerant behavior in the form of punctuated equilibria. One finds that the transition frequency matrix for transitions between patterns shows non-trivial statistical properties in the chaotic itinerant regime. We show that mixture input patterns can be temporally segmented by the itinerant dynamics. The viability of a combinatorial spatio-temporal neural code is also demonstrated.

  6. Spontaneous bursting: From temporal to spatio-temporal intermittency

    SciTech Connect

    Platt, N.; Hammel, S.M.

    1996-06-01

    A simple model for temporal bursting is introduced. This model invokes either dynamic or random forcing of a bifurcation parameter of some simple dynamical system in a way that makes the bifurcation parameter spend suitable amounts of time below and above the bifurcation threshold. This model is extended to coupled map lattices to produce spontaneous spatio-temporal burstings. It models physical systems which are embedded in a random background that is statistically homogeneous in space and time. An application of this model to optical turbulence is discussed. {copyright} {ital 1996 American Institute of Physics.}

  7. Temporal processing dysfunction in schizophrenia.

    PubMed

    Carroll, Christine A; Boggs, Jennifer; O'Donnell, Brian F; Shekhar, Anantha; Hetrick, William P

    2008-07-01

    Schizophrenia may be associated with a fundamental disturbance in the temporal coordination of information processing in the brain, leading to classic symptoms of schizophrenia such as thought disorder and disorganized and contextually inappropriate behavior. Despite the growing interest and centrality of time-dependent conceptualizations of the pathophysiology of schizophrenia, there remains a paucity of research directly examining overt timing performance in the disorder. Accordingly, the present study investigated timing in schizophrenia using a well-established task of time perception. Twenty-three individuals with schizophrenia and 22 non-psychiatric control participants completed a temporal bisection task, which required participants to make temporal judgments about auditory and visually presented durations ranging from 300 to 600 ms. Both schizophrenia and control groups displayed greater visual compared to auditory timing variability, with no difference between groups in the visual modality. However, individuals with schizophrenia exhibited less temporal precision than controls in the perception of auditory durations. These findings correlated with parameter estimates obtained from a quantitative model of time estimation, and provide evidence of a fundamental deficit in temporal auditory precision in schizophrenia. PMID:18262701

  8. The mechanisms of temporal inference

    NASA Technical Reports Server (NTRS)

    Fox, B. R.; Green, S. R.

    1987-01-01

    The properties of a temporal language are determined by its constituent elements: the temporal objects which it can represent, the attributes of those objects, the relationships between them, the axioms which define the default relationships, and the rules which define the statements that can be formulated. The methods of inference which can be applied to a temporal language are derived in part from a small number of axioms which define the meaning of equality and order and how those relationships can be propagated. More complex inferences involve detailed analysis of the stated relationships. Perhaps the most challenging area of temporal inference is reasoning over disjunctive temporal constraints. Simple forms of disjunction do not sufficiently increase the expressive power of a language while unrestricted use of disjunction makes the analysis NP-hard. In many cases a set of disjunctive constraints can be converted to disjunctive normal form and familiar methods of inference can be applied to the conjunctive sub-expressions. This process itself is NP-hard but it is made more tractable by careful expansion of a tree-structured search space.

  9. Parallel indexing technique for spatio-temporal data

    NASA Astrophysics Data System (ADS)

    He, Zhenwen; Kraak, Menno-Jan; Huisman, Otto; Ma, Xiaogang; Xiao, Jing

    2013-04-01

    The requirements for efficient access and management of massive multi-dimensional spatio-temporal data in geographical information system and its applications are well recognized and researched. The most popular spatio-temporal access method is the R-Tree and its variants. However, it is difficult to use them for parallel access to multi-dimensional spatio-temporal data because R-Trees, and variants thereof, are in hierarchical structures which have severe overlapping problems in high dimensional space. We extended a two-dimensional interval space representation of intervals to a multi-dimensional parallel space, and present a set of formulae to transform spatio-temporal queries into parallel interval set operations. This transformation reduces problems of multi-dimensional object relationships to simpler two-dimensional spatial intersection problems. Experimental results show that the new parallel approach presented in this paper has superior range query performance than R*-trees for handling multi-dimensional spatio-temporal data and multi-dimensional interval data. When the number of CPU cores is larger than that of the space dimensions, the insertion performance of this new approach is also superior to R*-trees. The proposed approach provides a potential parallel indexing solution for fast data retrieval of massive four-dimensional or higher dimensional spatio-temporal data.

  10. Macroscopic hotspots identification: A Bayesian spatio-temporal interaction approach.

    PubMed

    Dong, Ni; Huang, Helai; Lee, Jaeyoung; Gao, Mingyun; Abdel-Aty, Mohamed

    2016-07-01

    This study proposes a Bayesian spatio-temporal interaction approach for hotspot identification by applying the full Bayesian (FB) technique in the context of macroscopic safety analysis. Compared with the emerging Bayesian spatial and temporal approach, the Bayesian spatio-temporal interaction model contributes to a detailed understanding of differential trends through analyzing and mapping probabilities of area-specific crash trends as differing from the mean trend and highlights specific locations where crash occurrence is deteriorating or improving over time. With traffic analysis zones (TAZs) crash data collected in Florida, an empirical analysis was conducted to evaluate the following three approaches for hotspot identification: FB ranking using a Poisson-lognormal (PLN) model, FB ranking using a Bayesian spatial and temporal (B-ST) model and FB ranking using a Bayesian spatio-temporal interaction (B-ST-I) model. The results show that (a) the models accounting for space-time effects perform better in safety ranking than does the PLN model, and (b) the FB approach using the B-ST-I model significantly outperforms the B-ST approach in correctly identifying hotspots by explicitly accounting for the space-time variation in addition to the stable spatial/temporal patterns of crash occurrence. In practice, the B-ST-I approach plays key roles in addressing two issues: (a) how the identified hotspots have evolved over time and (b) the identification of areas that, whilst not yet hotspots, show a tendency to become hotspots. Finally, it can provide guidance to policy decision makers to efficiently improve zonal-level safety. PMID:27110645

  11. Contact process with temporal disorder.

    PubMed

    Barghathi, Hatem; Vojta, Thomas; Hoyos, José A

    2016-08-01

    We investigate the influence of time-varying environmental noise, i.e., temporal disorder, on the nonequilibrium phase transition of the contact process. Combining a real-time renormalization group, scaling theory, and large scale Monte-Carlo simulations in one and two dimensions, we show that the temporal disorder gives rise to an exotic critical point. At criticality, the effective noise amplitude diverges with increasing time scale, and the probability distribution of the density becomes infinitely broad, even on a logarithmic scale. Moreover, the average density and survival probability decay only logarithmically with time. This infinite-noise critical behavior can be understood as the temporal counterpart of infinite-randomness critical behavior in spatially disordered systems, but with exchanged roles of space and time. We also analyze the generality of our results, and we discuss potential experiments. PMID:27627250

  12. [Diagnostic evaluation of temporal paragangliomas].

    PubMed

    Szymańska, Anna; Gołabek, Wiesław; Szymański, Marcin; Morshed, Kamal; Trojanowska, Agnieszka

    2007-01-01

    Paragangliomas are rare tumours deriving from paraganglia--small bodies of neuroendocrine tissue. Approximately 3% of paragangliomas occur in the head and neck area accounting for about 0,6% of all tumours of this region. Head and neck paragangliomas are divided into two groups: neck tumours (carotid body tumor and vagal paraganglioma) and temporal paragangliomas (jugular bulb tumor and tympanic paraganglioma). Temporal paragangliomas arise from paraganglia located in the petrous part of the temporal bone. Radiological evaluation of these lesions is essential for confirming the diagnosis and surgery planning. Most useful methods are magnetic resonance imaging and computed tomography. These modalities deliver important information about tumour location, extension and the state of the surrounding structures. Carotid angiography is a second step diagnostic method, performed in patients with jugular bulb paraganglioma. It has a diagnostic value and allows palliative or preoperative embolization of the tumor. Ultrasonographic evaluation and scintigraphy also provide advantages in diagnostic management. PMID:18546938

  13. Contact process with temporal disorder

    NASA Astrophysics Data System (ADS)

    Barghathi, Hatem; Vojta, Thomas; Hoyos, José A.

    2016-08-01

    We investigate the influence of time-varying environmental noise, i.e., temporal disorder, on the nonequilibrium phase transition of the contact process. Combining a real-time renormalization group, scaling theory, and large scale Monte-Carlo simulations in one and two dimensions, we show that the temporal disorder gives rise to an exotic critical point. At criticality, the effective noise amplitude diverges with increasing time scale, and the probability distribution of the density becomes infinitely broad, even on a logarithmic scale. Moreover, the average density and survival probability decay only logarithmically with time. This infinite-noise critical behavior can be understood as the temporal counterpart of infinite-randomness critical behavior in spatially disordered systems, but with exchanged roles of space and time. We also analyze the generality of our results, and we discuss potential experiments.

  14. Processing Temporal Constraints: An ERP Study

    ERIC Educational Resources Information Center

    Baggio, Giosue

    2008-01-01

    This article investigates how linguistic expressions of time--in particular, temporal adverbs and verb tense morphemes--are used to establish temporal reference at the level of brain physiology. First, a formal semantic analysis of tense and temporal adverbs is outlined. It is argued that computing temporal reference amounts to solving a…

  15. Closed-Cycle, Frequency-Stable CO2 Laser Technology

    NASA Technical Reports Server (NTRS)

    Batten, Carmen E. (Editor); Miller, Irvin M. (Editor); Wood, George M., Jr. (Editor); Willetts, David V. (Editor)

    1987-01-01

    These proceedings contain a collection of papers and comments presented at a workshop on technology associated with long-duration closed-cycle operation of frequency-stable, pulsed carbon dioxide lasers. This workshop was held at the NASA Langley Research Center June 10 to 12, 1986. The workshop, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the Royal Signals and Radar Establishment (RSRE), was attended by 63 engineers and scientists from the United States and the United Kingdom. During the 2 1/2 days of the workshop, a number of issues relating to obtaining frequency-stable operation and to the catalytic control of laser gas chemistry were discussed, and specific recommendations concerning future activities were drafted.

  16. Detailed temporal structure of communication networks in groups of songbirds

    PubMed Central

    Clayton, David

    2016-01-01

    Animals in groups often exchange calls, in patterns whose temporal structure may be influenced by contextual factors such as physical location and the social network structure of the group. We introduce a model-based analysis for temporal patterns of animal call timing, originally developed for networks of firing neurons. This has advantages over cross-correlation analysis in that it can correctly handle common-cause confounds and provides a generative model of call patterns with explicit parameters for the influences between individuals. It also has advantages over standard Markovian analysis in that it incorporates detailed temporal interactions which affect timing as well as sequencing of calls. Further, a fitted model can be used to generate novel synthetic call sequences. We apply the method to calls recorded from groups of domesticated zebra finch (Taeniopygia guttata) individuals. We find that the communication network in these groups has stable structure that persists from one day to the next, and that ‘kernels’ reflecting the temporal range of influence have a characteristic structure for a calling individual's effect on itself, its partner and on others in the group. We further find characteristic patterns of influences by call type as well as by individual. PMID:27335223

  17. Detailed temporal structure of communication networks in groups of songbirds.

    PubMed

    Stowell, Dan; Gill, Lisa; Clayton, David

    2016-06-01

    Animals in groups often exchange calls, in patterns whose temporal structure may be influenced by contextual factors such as physical location and the social network structure of the group. We introduce a model-based analysis for temporal patterns of animal call timing, originally developed for networks of firing neurons. This has advantages over cross-correlation analysis in that it can correctly handle common-cause confounds and provides a generative model of call patterns with explicit parameters for the influences between individuals. It also has advantages over standard Markovian analysis in that it incorporates detailed temporal interactions which affect timing as well as sequencing of calls. Further, a fitted model can be used to generate novel synthetic call sequences. We apply the method to calls recorded from groups of domesticated zebra finch (Taeniopygia guttata) individuals. We find that the communication network in these groups has stable structure that persists from one day to the next, and that 'kernels' reflecting the temporal range of influence have a characteristic structure for a calling individual's effect on itself, its partner and on others in the group. We further find characteristic patterns of influences by call type as well as by individual. PMID:27335223

  18. Carrier-envelope-phase stable, high-contrast, double chirped-pulse-amplification laser system.

    PubMed

    Jullien, Aurélie; Ricci, Aurélien; Böhle, Frederik; Rousseau, Jean-Philippe; Grabielle, Stéphanie; Forget, Nicolas; Jacqmin, Hermance; Mercier, Brigitte; Lopez-Martens, Rodrigo

    2014-07-01

    We present the first carrier-envelope-phase stable chirped-pulse amplifier (CPA) featuring high temporal contrast for relativistic intensity laser-plasma interactions at 1 kHz repetition rate. The laser is based on a double-CPA architecture including cross-polarized wave (XPW) filtering technique and a high-energy grism-based compressor. The 8 mJ, 22 fs pulses feature 10⁻¹¹ temporal contrast at -20  ps and a carrier-envelope-phase drift of 240 mrad root mean square. PMID:24978734

  19. High Frequency Stable Oscillate boiling

    NASA Astrophysics Data System (ADS)

    Li, Fenfang; Gonzalez-Avila, Silvestre Roberto; Ohl, Claus Dieter

    2015-11-01

    We present an unexpected regime of resonant bubble oscillations on a thin metal film submerged in water, which is continuously heated with a focused CW laser. The oscillatory bubble dynamics reveals a remarkably stable frequency of several 100 kHz and is resolved from the side using video recordings at 1 million frames per second. The emitted sound is measured simultaneously and shows higher harmonics. Once the laser is switched on the water in contact with the metal layer is superheated and an explosively expanding cavitation bubble is generated. However, after the collapse a microbubble is nucleated from the bubble remains which displays long lasting oscillations. Generally, pinch-off from of the upper part of the microbubble is observed generating a continuous stream of small gas bubbles rising upwards. The cavitation expansion, collapse, and the jetting of gas bubbles are detected by the hydrophone and are correlated to the high speed video. We find the bubble oscillation frequency is dependent on the bubble size and surface tension. A preliminary model based on Marangoni flow and heat transfer can explain the high flow velocities observed, yet the origin of bubble oscillation is currently not well understood.

  20. Evolutionary routes to stable ownership.

    PubMed

    Hare, D; Reeve, H K; Blossey, B

    2016-06-01

    Ownership can evolve in potentially any species. Drawing on insights from across disciplines, we distinguish between possession and ownership and present species-neutral criteria for ownership, defined as respect for possession. We use a variant of the tug-of-war evolutionary game to demonstrate how ownership can evolve in the form of a new, biologically realistic strategy, Restraint With Retaliation (RWR). In our game, resource holding potential (RHP) is assumed to be equal between interactants, and resource holding asymmetry determines whether ownership is adaptive. RWR will be evolutionarily stable when the ratio of resource holdings between interactants is relatively low, but not when this ratio is sufficiently high. We offer RWR as one evolutionary route to ownership among many, and discuss how ownership unites previously described behavioural phenomena across taxa. We propose that some but not all mechanisms of territory formation and maintenance can be considered ownership, and show that territories are not the only resources that can be owned. We argue that ownership can be a powerful cooperative solution to tragedies of the commons and problems of collective action throughout the biological world. We advance recent scholarship that has begun to investigate the biological importance of ownership, and we call for a comprehensive account of its evolutionary logic and taxonomic distribution. We propose that ownership should be considered a fundamental, unifying biological phenomenon. PMID:26991035

  1. Stable microbial community composition on the Greenland Ice Sheet.

    PubMed

    Musilova, Michaela; Tranter, Martyn; Bennett, Sarah A; Wadham, Jemma; Anesio, Alexandre M

    2015-01-01

    The first molecular-based studies of microbes in snow and on glaciers have only recently been performed on the vast Greenland Ice Sheet (GrIS). Aeolian microbial seeding is hypothesized to impact on glacier surface community compositions. Localized melting of glacier debris (cryoconite) into the surface ice forms cryoconite holes, which are considered 'hot spots' for microbial activity on glaciers. To date, few studies have attempted to assess the origin and evolution of cryoconite and cryoconite hole communities throughout a melt season. In this study, a range of experimental approaches was used for the first time to study the inputs, temporal and structural transformations of GrIS microbial communities over the course of a whole ablation season. Small amounts of aeolian (wind and snow) microbes were potentially seeding the stable communities that were already present on the glacier (composed mainly of Proteobacteria, Cyanobacteria, and Actinobacteria). However, the dominant bacterial taxa in the aeolian samples (Firmicutes) did not establish themselves in local glacier surface communities. Cryoconite and cryoconite hole community composition remained stable throughout the ablation season following the fast community turnover, which accompanied the initial snow melt. The presence of stable communities in cryoconite and cryoconite holes on the GrIS will allow future studies to assess glacier surface microbial diversity at individual study sites from sampling intervals of short duration only. Aeolian inputs also had significantly different organic δ(13)C values (-28.0 to -27.0‰) from the glacier surface values (-25.7 to -23.6‰), indicating that in situ microbial processes are important in fixing new organic matter and transforming aeolian organic carbon. The continuous productivity of stable communities over one melt season makes them important contributors to biogeochemical nutrient cycling on glaciers. PMID:25852658

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

    PubMed Central

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

    2012-01-01

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

  3. A Structural Characterization of Temporal Dynamic Controllability

    NASA Technical Reports Server (NTRS)

    Morris, Paul

    2006-01-01

    An important issue for temporal planners is the ability to handle temporal uncertainty. Recent papers have addressed the question of how to tell whether a temporal network is Dynamically Controllable, i.e., whether the temporal requirements are feasible in the light of uncertain durations of some processes. Previous work has presented an O(N5) algorithm for testing this property. Here, we introduce a new analysis of temporal cycles that leads to an O(N4) algorithm.

  4. Infections on Temporal Networks—A Matrix-Based Approach

    PubMed Central

    Koher, Andreas; Lentz, Hartmut H. K.; Hövel, Philipp; Sokolov, Igor M.

    2016-01-01

    We extend the concept of accessibility in temporal networks to model infections with a finite infectious period such as the susceptible-infected-recovered (SIR) model. This approach is entirely based on elementary matrix operations and unifies the disease and network dynamics within one algebraic framework. We demonstrate the potential of this formalism for three examples of networks with high temporal resolution: networks of social contacts, sexual contacts, and livestock-trade. Our investigations provide a new methodological framework that can be used, for instance, to estimate the epidemic threshold, a quantity that determines disease parameters, for which a large-scale outbreak can be expected. PMID:27035128

  5. Infections on Temporal Networks--A Matrix-Based Approach.

    PubMed

    Koher, Andreas; Lentz, Hartmut H K; Hövel, Philipp; Sokolov, Igor M

    2016-01-01

    We extend the concept of accessibility in temporal networks to model infections with a finite infectious period such as the susceptible-infected-recovered (SIR) model. This approach is entirely based on elementary matrix operations and unifies the disease and network dynamics within one algebraic framework. We demonstrate the potential of this formalism for three examples of networks with high temporal resolution: networks of social contacts, sexual contacts, and livestock-trade. Our investigations provide a new methodological framework that can be used, for instance, to estimate the epidemic threshold, a quantity that determines disease parameters, for which a large-scale outbreak can be expected. PMID:27035128

  6. Psychosis and temporal lobe epilepsy-role of electroconvulsive therapy.

    PubMed

    Anderson, Naomi Mifflen; Gadit, Amin

    2012-01-01

    A 49-year-old female presented for admission with features of being withdrawn, inability to comprehend questions, auditory hallucinations and disorganised thoughts. She also had a previous diagnosis of temporal lobe epilepsy. She did not respond well to psychotropic medications. During her sleep deprived EEG, she had a brief episode of seizures. Following this, she showed improvement in psychosis for a day or so. Based on this finding, it was decided to initiate a course of electroconvulsive therapy. She improved remarkably on six treatments. At the time of discharge, she was in a stable condition. PMID:22729342

  7. Dynamics of temporal learning rules

    NASA Astrophysics Data System (ADS)

    Roberts, Patrick D.

    2000-09-01

    The changes of synaptic strength are analyzed on two time scales: the fast local field dynamics, and the slow synaptic modification dynamics. The fast dynamics are determined by the synaptic strengths and background noise in the system. The slow dynamics are determined by the functional form of a temporal learning rule. Temporal learning rules are defined to be functions yielding state dependent changes in synaptic strengths depending on the timing of pre- and postsynaptic states in the network. The evolution of local field dynamics that result from various learning rules are analyzed for a stochastic, discrete time neural model with no relative refractory period that receives a series of delayed adaptive inputs. A fixed point is found in the learning dynamics, and conditions for two types of instabilities are analyzed. Four universality classes of dynamics are found that are independent of the details of the temporal learning rules. Examples are given of biological systems in which these temporal learning rules have been identified, and their functional consequences are discussed.

  8. Temporal scaling in information propagation

    NASA Astrophysics Data System (ADS)

    Huang, Junming; Li, Chao; Wang, Wen-Qiang; Shen, Hua-Wei; Li, Guojie; Cheng, Xue-Qi

    2014-06-01

    For the study of information propagation, one fundamental problem is uncovering universal laws governing the dynamics of information propagation. This problem, from the microscopic perspective, is formulated as estimating the propagation probability that a piece of information propagates from one individual to another. Such a propagation probability generally depends on two major classes of factors: the intrinsic attractiveness of information and the interactions between individuals. Despite the fact that the temporal effect of attractiveness is widely studied, temporal laws underlying individual interactions remain unclear, causing inaccurate prediction of information propagation on evolving social networks. In this report, we empirically study the dynamics of information propagation, using the dataset from a population-scale social media website. We discover a temporal scaling in information propagation: the probability a message propagates between two individuals decays with the length of time latency since their latest interaction, obeying a power-law rule. Leveraging the scaling law, we further propose a temporal model to estimate future propagation probabilities between individuals, reducing the error rate of information propagation prediction from 6.7% to 2.6% and improving viral marketing with 9.7% incremental customers.

  9. Combining Simultaneous with Temporal Masking

    ERIC Educational Resources Information Center

    Hermens, Frouke; Herzog, Michael H.; Francis, Gregory

    2009-01-01

    Simultaneous and temporal masking are two frequently used techniques in psychology and vision science. Although there are many studies and theories related to each masking technique, there are no systematic investigations of their mutual relationship, even though both techniques are often applied together. Here, the authors show that temporal…

  10. Temporal resolution in fluorescence imaging

    PubMed Central

    Mondal, Partha Pratim

    2014-01-01

    Temporal resolution is a key factor for imaging rapidly occurring events in biology. In this feature article, I investigate an approximate estimate for determining the temporal resolution limit. The condition that led to this limit is, the time taken by the ensemble (99.9%) of excited molecules to relax to ground state, assuming all the emitted photons are detected. In a simplistic three-level system, the temporal resolution is, ≈3τp, where τp = (loge10)/(kf + knr) and, kf and knr are respectively the radiative and non-radiative emission rates. This further assumes the ideal condition that, the quantum efficiency of the detector is unity and there are no other loses. We discuss few state-of-art microscopy techniques that are capable of high temporal resolution. This includes techniques such as multifocal multiphoton microscopy (MMM), multifocal plane microscopy, multiple excitation spot optical microscopy (MESO), multiplane microscopy and multiple light-sheet microscopy (MLSM). PMID:25988152

  11. Temporal Processing Dysfunction in Schizophrenia

    ERIC Educational Resources Information Center

    Carroll, Christine A.; Boggs, Jennifer; O'Donnell, Brian F.; Shekhar, Anantha; Hetrick, William P.

    2008-01-01

    Schizophrenia may be associated with a fundamental disturbance in the temporal coordination of information processing in the brain, leading to classic symptoms of schizophrenia such as thought disorder and disorganized and contextually inappropriate behavior. Despite the growing interest and centrality of time-dependent conceptualizations of the…

  12. Temporal scaling in information propagation.

    PubMed

    Huang, Junming; Li, Chao; Wang, Wen-Qiang; Shen, Hua-Wei; Li, Guojie; Cheng, Xue-Qi

    2014-01-01

    For the study of information propagation, one fundamental problem is uncovering universal laws governing the dynamics of information propagation. This problem, from the microscopic perspective, is formulated as estimating the propagation probability that a piece of information propagates from one individual to another. Such a propagation probability generally depends on two major classes of factors: the intrinsic attractiveness of information and the interactions between individuals. Despite the fact that the temporal effect of attractiveness is widely studied, temporal laws underlying individual interactions remain unclear, causing inaccurate prediction of information propagation on evolving social networks. In this report, we empirically study the dynamics of information propagation, using the dataset from a population-scale social media website. We discover a temporal scaling in information propagation: the probability a message propagates between two individuals decays with the length of time latency since their latest interaction, obeying a power-law rule. Leveraging the scaling law, we further propose a temporal model to estimate future propagation probabilities between individuals, reducing the error rate of information propagation prediction from 6.7% to 2.6% and improving viral marketing with 9.7% incremental customers. PMID:24939414

  13. Advanced thermally stable jet fuels

    SciTech Connect

    Schobert, H.H.

    1999-01-31

    The Pennsylvania State University program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) Development of mechanisms of degradation and solids formation; (2) Quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) Characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) Elucidation of the role of additives in retarding the formation of carbonaceous solids; (5) Assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Future high-Mach aircraft will place severe thermal demands on jet fuels, requiring the development of novel, hybrid fuel mixtures capable of withstanding temperatures in the range of 400--500 C. In the new aircraft, jet fuel will serve as both an energy source and a heat sink for cooling the airframe, engine, and system components. The ultimate development of such advanced fuels requires a thorough understanding of the thermal decomposition behavior of jet fuels under supercritical conditions. Considering that jet fuels consist of hundreds of compounds, this task must begin with a study of the thermal degradation behavior of select model compounds under supercritical conditions. The research performed by The Pennsylvania State University was focused on five major tasks that reflect the objectives stated above: Task 1: Investigation of the Quantitative Degradation of Fuels; Task 2: Investigation of Incipient Deposition; Task 3: Characterization of Solid Gums, Sediments, and Carbonaceous Deposits; Task 4: Coal-Based Fuel Stabilization Studies; and Task 5: Exploratory Studies on the Direct Conversion of Coal to High Quality Jet Fuels. The major findings of each of these tasks are presented in this executive summary. A description of the sub-tasks performed under each of these tasks and the findings of those studies are provided in the remainder of this volume

  14. Leucine metabolism in stable cirrhosis.

    PubMed

    Mullen, K D; Denne, S C; McCullough, A J; Savin, S M; Bruno, D; Tavill, A S; Kalhan, S C

    1986-01-01

    Alterations in protein and amino acid metabolism have been postulated to explain the frequent observations of muscle wasting and decreased plasma branched-chain amino acid concentrations in cirrhosis. In order to investigate the changes in protein metabolism, we have measured the rates of leucine turnover and oxidation in six stable, biopsy-proven cirrhotics and six age and sex-matched healthy control subjects after an overnight fast, using [1-13C]leucine tracer. Following a primed constant-rate infusion of [1-13C]leucine, the 13C enrichments of plasma leucine and expired CO2 were used to estimate leucine turnover and oxidation, respectively. Fat-free body mass was estimated from the measurements of total body water as quantified by H2[18O] tracer dilution. The rates of CO2 production and oxygen consumption were measured hourly during the study period, using open-circuit respiratory calorimetry. Urinary urea, ammonia and total nitrogen excretion rates were quantified from timed urine samples. Even though the plasma leucine levels were lower in cirrhotics as compared with controls (100.5 +/- 17.1 vs. 138.3 +/- 20.4 mumoles per liter, mean +/- S.D., p less than 0.001), the rates of leucine turnover were not significantly different in the two groups (89.4 +/- 19.0 vs. 87.8 +/- 19.0 mumoles per kg X hr). In contrast, the rates of leucine oxidation were significantly reduced in cirrhosis (8.1 +/- 2.5 vs. 12.7 +/- 3.1 mumoles per kg X hr, p less than 0.01). When all subjects were considered, the leucine oxidation rate was correlated with plasma leucine concentration (r = 0.62, p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3089896

  15. Directional flow sensing by passively stable larvae.

    PubMed

    Fuchs, Heidi L; Christman, Adam J; Gerbi, Gregory P; Hunter, Elias J; Diez, F Javier

    2015-09-01

    Mollusk larvae have a stable, velum-up orientation that may influence how they sense and react to hydrodynamic signals applied in different directions. Directional sensing abilities and responses could affect how a larva interacts with anisotropic fluid motions, including those in feeding currents and in boundary layers encountered during settlement. Oyster larvae (Crassostrea virginica) were exposed to simple shear in a Couette device and to solid-body rotation in a single rotating cylinder. Both devices were operated in two different orientations, one with the axis of rotation parallel to the gravity vector, and one with the axis perpendicular. Larvae and flow were observed simultaneously with near-infrared particle-image velocimetry, and behavior was quantified as a response to strain rate, vorticity and centripetal acceleration. Only flows rotating about a horizontal axis elicited the diving response observed previously for oyster larvae in turbulence. The results provide strong evidence that the turbulence-sensing mechanism relies on gravity-detecting organs (statocysts) rather than mechanosensors (cilia). Flow sensing with statocysts sets oyster larvae apart from zooplankters such as copepods and protists that use external mechanosensors in sensing spatial velocity gradients generated by prey or predators. Sensing flow-induced changes in orientation, rather than flow deformation, would enable more efficient control of vertical movements. Statocysts provide larvae with a mechanism of maintaining their upward swimming when rotated by vortices and initiating dives toward the seabed in response to the strong turbulence associated with adult habitats. PMID:26333930

  16. Stable Isotope Database: present and past archives

    NASA Astrophysics Data System (ADS)

    Bolliet, Timothé

    2014-05-01

    Paleoclimate data provide benchmarks against which the realism of the processes simulated by climate models can be assessed. Within this framework, it is essential to avoid introducing uncertainties associated with transfer functions and therefore to operate with robust proxies. The implementation of stable isotopes of water or carbon inside climate models motivates a synthesis of available data. Supported by the LABEX L-IPSL and involving a team of climate modelers and paleoclimatologists, this project aims to establish a worldwide database of δ18O, δD δ17O and δ13C from oceanic microfossils, corals, ice cores, cave speleothems, lakes, tree rings, and vegetation leaves wax. The aim is to provide a global vision of the hydrological cycle during the LGM and other selected key periods (last 2000 years, Mid-Holocene, Dansgaard-Oeschger events, and the Eemian). It requires screening through hundreds of published oceanic and continental records, validating the selection of the data based on resolution and chronological information. We extracted ~900 dated δ18O records from 650 marine sediment cores, 65 δ18O records from 50 ice cores, ~200 δ18O speleothems records from 60 caves, and 540 δ13C records from 290 marine sediment cores. An additional aspect of this project consists in the construction of an online portal providing an intuitive and interactive platform allowing selecting, visualizing, and downloading of the records included in this database, thus improving the distribution and comparison of paleoclimatic records from various sites.

  17. Low energy stable plasma calibration facility

    NASA Astrophysics Data System (ADS)

    Frederick-Frost, K. M.; Lynch, K. A.

    2007-07-01

    We have designed and fabricated a low energy plasma calibration facility for testing and calibration of rocket-borne charged-particle detectors and for the investigation of plasma sheath formation in an environment with ionospheric plasma energies, densities, and Debye lengths. We describe the vacuum system and associated plasma source, which was modified from a Naval Research Laboratory design [Bowles et al. Rev. Sci. Instrum. 67, 455 (1996)]. Mechanical and electrical modifications to this cylindrical microwave resonant source are outlined together with a different method of operating the magnetron that achieves a stable discharge. This facility produces unmagnetized plasmas with densities from 1×103/cm3to6×105/cm3, electron temperatures from 0.1to1.7eV, and plasma potentials from 0.5to8V depending on varying input microwave power and neutral gas flow. For the range of input microwave power explored (350-600W), the energy density of the plasma remains constant because of an inverse relationship between density and temperature. This relationship allows a wide range of Debye lengths (0.3-8.4cm) to be investigated, which is ideal for simulating the ionospheric plasma sheaths we explore.

  18. Temporal Coding of Volumetric Imagery

    NASA Astrophysics Data System (ADS)

    Llull, Patrick Ryan

    'Image volumes' refer to realizations of images in other dimensions such as time, spectrum, and focus. Recent advances in scientific, medical, and consumer applications demand improvements in image volume capture. Though image volume acquisition continues to advance, it maintains the same sampling mechanisms that have been used for decades; every voxel must be scanned and is presumed independent of its neighbors. Under these conditions, improving performance comes at the cost of increased system complexity, data rates, and power consumption. This dissertation explores systems and methods capable of efficiently improving sensitivity and performance for image volume cameras, and specifically proposes several sampling strategies that utilize temporal coding to improve imaging system performance and enhance our awareness for a variety of dynamic applications. Video cameras and camcorders sample the video volume (x,y,t) at fixed intervals to gain understanding of the volume's temporal evolution. Conventionally, one must reduce the spatial resolution to increase the framerate of such cameras. Using temporal coding via physical translation of an optical element known as a coded aperture, the compressive temporal imaging (CACTI) camera emonstrates a method which which to embed the temporal dimension of the video volume into spatial (x,y) measurements, thereby greatly improving temporal resolution with minimal loss of spatial resolution. This technique, which is among a family of compressive sampling strategies developed at Duke University, temporally codes the exposure readout functions at the pixel level. Since video cameras nominally integrate the remaining image volume dimensions (e.g. spectrum and focus) at capture time, spectral (x,y,t,lambda) and focal (x,y,t,z) image volumes are traditionally captured via sequential changes to the spectral and focal state of the system, respectively. The CACTI camera's ability to embed video volumes into images leads to exploration

  19. Temporal judgments in multi-sensory space.

    PubMed

    Retsa, Chrysa; Naish, Peter; Bekinschtein, Tristan; Bak, Thomas H

    2016-07-29

    To successfully interact with the environment requires a combination of stimulus recognition as well as localization in both space and time, with information moreover coming from multiple senses. Several studies have shown that auditory stimuli last subjectively longer than visual ones of equal duration. Recently, it has also been suggested that stimulus position affects duration perception. The present study investigated how lateral spatial presentation influences sub-second visual and auditory duration judgments. Five experiments were conducted using the duration discrimination paradigm, wherein two stimuli are presented sequentially and participants are asked to judge whether the second stimulus (comparison) is shorter or longer in duration than the first (standard). The number of stimulus positions and the way in which different modality trials were presented (mixed or blocked) varied. Additionally, comparisons were made either within or across modalities. No stable effect of location itself was found. However, in mixed modality experiments there was a clear over-estimation of duration in visual trials when the location of the comparison was different from the standard. This effect was reversed in the same location trials. Auditory judgments were unaffected by location manipulations. Based on these results, we propose the existence of an error-mechanism, according to which a specific duration is added in order to compensate for the loss of duration perception caused by spatial attention shifts between different locations. This mechanism is revealed in spatial and modality-mixed circumstances wherein its over-activation results in a systematic temporal bias. PMID:26898372

  20. Temporal-kernel recurrent neural networks.

    PubMed

    Sutskever, Ilya; Hinton, Geoffrey

    2010-03-01

    A Recurrent Neural Network (RNN) is a powerful connectionist model that can be applied to many challenging sequential problems, including problems that naturally arise in language and speech. However, RNNs are extremely hard to train on problems that have long-term dependencies, where it is necessary to remember events for many timesteps before using them to make a prediction. In this paper we consider the problem of training RNNs to predict sequences that exhibit significant long-term dependencies, focusing on a serial recall task where the RNN needs to remember a sequence of characters for a large number of steps before reconstructing it. We introduce the Temporal-Kernel Recurrent Neural Network (TKRNN), which is a variant of the RNN that can cope with long-term dependencies much more easily than a standard RNN, and show that the TKRNN develops short-term memory that successfully solves the serial recall task by representing the input string with a stable state of its hidden units. PMID:19932002

  1. On Nonstable and Stable Population Momentum

    PubMed Central

    Olgiati, Analia S.; Levin, Simon A.

    2014-01-01

    This article decomposes total population momentum into two constituent and multiplicative parts: “nonstable” momentum and “stable” momentum. Nonstable momentum depends on deviations between a population’s current age distribution and its implied stable age distribution. Stable momentum is a function of deviations between a population’s implied stable and stationary age distributions. In general, the factorization of total momentum into the product of nonstable and stable momentum is a very good approximation. The factorization is exact, however, when the current age distribution is stable or when observed fertility is already at replacement. We provide numerical illustrations by calculating nonstable, stable, and total momentum for 176 countries, the world, and its major regions. In short, the article brings together disparate strands of the population momentum literature and shows how the various kinds of momentum fit together into a single unifying framework. PMID:21948106

  2. Spatio-temporal generation regimes in quasi-CW Raman fiber lasers.

    PubMed

    Tarasov, Nikita; Sugavanam, Srikanth; Churkin, Dmitry

    2015-09-21

    We present experimental measurements of intensity spatio-temporal dynamics in quasi-CW Raman fiber laser. Depending on the power, the laser operates in different spatio-temporal regimes varying from partial mode-locking near the generation threshold to almost stochastic radiation and a generation of short-lived pulses at high power. The transitions between the generation regimes are evident in intensity spatio-temporal dynamics. Two-dimensional auto-correlation functions provide an additional insight into temporal and spatial properties of the observed regimes. PMID:26406625

  3. Updating representations of temporal intervals.

    PubMed

    Danckert, James; Anderson, Britt

    2015-12-01

    Effectively engaging with the world depends on accurate representations of the regularities that make up that world-what we call mental models. The success of any mental model depends on the ability to adapt to changes-to 'update' the model. In prior work, we have shown that damage to the right hemisphere of the brain impairs the ability to update mental models across a range of tasks. Given the disparate nature of the tasks we have employed in this prior work (i.e. statistical learning, language acquisition, position priming, perceptual ambiguity, strategic game play), we propose that a cognitive module important for updating mental representations should be generic, in the sense that it is invoked across multiple cognitive and perceptual domains. To date, the majority of our tasks have been visual in nature. Given the ubiquity and import of temporal information in sensory experience, we examined the ability to build and update mental models of time. We had healthy individuals complete a temporal prediction task in which intervals were initially drawn from one temporal range before an unannounced switch to a different range of intervals. Separate groups had the second range of intervals switch to one that contained either longer or shorter intervals than the first range. Both groups showed significant positive correlations between perceptual and prediction accuracy. While each group updated mental models of temporal intervals, those exposed to shorter intervals did so more efficiently. Our results support the notion of generic capacity to update regularities in the environment-in this instance based on temporal information. The task developed here is well suited to investigations in neurological patients and in neuroimaging settings. PMID:26303026

  4. Temporal Stability of Genetic Variability and Differentiation in the Three-Spined Stickleback (Gasterosteus aculeatus)

    PubMed Central

    DeFaveri, Jacquelin; Merilä, Juha

    2015-01-01

    Temporal variation in allele frequencies, whether caused by deterministic or stochastic forces, can inform us about interesting demographic and evolutionary phenomena occurring in wild populations. In spite of the continued surge of interest in the genetics of three-spined stickleback (Gasterosteus aculeatus) populations, little attention has been paid towards the temporal stability of allele frequency distributions, and whether there are consistent differences in effective size (Ne) of local populations. We investigated temporal stability of genetic variability and differentiation in 15 microsatellite loci within and among eight collection sites of varying habitat type, surveyed twice over a six-year time period. In addition, Nes were estimated with the expectation that they would be lowest in isolated ponds, intermediate in larger lakes and largest in open marine sites. In spite of the marked differences in genetic variability and differentiation among the study sites, the temporal differences in allele frequencies, as well as measures of genetic diversity and differentiation, were negligible. Accordingly, the Ne estimates were temporally stable, but tended to be lower in ponds than in lake or marine habitats. Hence, we conclude that allele frequencies in putatively neutral markers in three-spined sticklebacks seem to be temporally stable – at least over periods of few generations – across a wide range of habitat types differing markedly in levels of genetic variability, effective population size and gene flow. PMID:25853707

  5. Ultraviolet and thermally stable polymer compositions

    NASA Technical Reports Server (NTRS)

    Adamson, M. J.; Gloria, H. R.; Goldsberry, R. E.; Reinisch, R. F.

    1972-01-01

    Copolymers, produced from aromatic substituted aromatic azine-siloxane compositions, are thermally stable, solar ultraviolet light non-degradable by wavelengths shorter than those reaching earth surface.

  6. Stable molecular configuration in crystalline carboxylic acids

    NASA Astrophysics Data System (ADS)

    Hayashi, Soichi; Umemura, Junzo; Nakamura, Ryoko

    1980-12-01

    The stable (lower enthalpy) molecular configurations of propionic, butyric, Jeric and lauric acids in the crystalline state have been examined via their atom-atom potentials. It was found that the cis configuration is more stable than the trans configuration for propionic, butyric and valeric acids, and that the trans configuration is more stable than the cis configuration for lauric acid, in accord with a previous IR spectral analysis. The potential energy of benzoic acid was recalculated using the positions of atoms given by Speakman, and indicates that the A form is more stable than the B form, in agreement with the results of previous work.

  7. Temporal motifs in time-dependent networks

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    Temporal networks are commonly used to represent systems where connections between elements are active only for restricted periods of time, such as telecommunication, neural signal processing, biochemical reaction and human social interaction networks. We introduce the framework of temporal motifs to study the mesoscale topological-temporal structure of temporal networks in which the events of nodes do not overlap in time. Temporal motifs are classes of similar event sequences, where the similarity refers not only to topology but also to the temporal order of the events. We provide a mapping from event sequences to coloured directed graphs that enables an efficient algorithm for identifying temporal motifs. We discuss some aspects of temporal motifs, including causality and null models, and present basic statistics of temporal motifs in a large mobile call network.

  8. Temporal shape analysis via the spectral signature.

    PubMed

    Bernardis, Elena; Konukoglu, Ender; Ou, Yangming; Metaxas, Dimitris N; Desjardins, Benoit; Pohl, Kilian M

    2012-01-01

    In this paper, we adapt spectral signatures for capturing morphological changes over time. Advanced techniques for capturing temporal shape changes frequently rely on first registering the sequence of shapes and then analyzing the corresponding set of high dimensional deformation maps. Instead, we propose a simple encoding motivated by the observation that small shape deformations lead to minor refinements in the spectral signature composed of the eigenvalues of the Laplace operator. The proposed encoding does not require registration, since spectral signatures are invariant to pose changes. We apply our representation to the shapes of the ventricles extracted from 22 cine MR scans of healthy controls and Tetralogy of Fallot patients. We then measure the accuracy score of our encoding by training a linear classifier, which outperforms the same classifier based on volumetric measurements. PMID:23286031

  9. Massive Cerebrospinal Fluid Leak of the Temporal Bone

    PubMed Central

    Manno, Alessandra; Pasqualitto, Emanuela; Ciofalo, Andrea; Angeletti, Diletta; Pasquariello, Benedetta

    2016-01-01

    Cerebrospinal fluid (CSF) leakage of the temporal bone region is defined as abnormal communications between the subarachnoidal space and the air-containing spaces of the temporal bone. CSF leak remains one of the most frequent complications after VS surgery. Radiotherapy is considered a predisposing factor for development of temporal bone CSF leak because it may impair dural repair mechanisms, thus causing inadequate dural sealing. The authors describe the case of a 47-year-old man with a massive effusion of CSF which extended from the posterior and lateral skull base to the first cervical vertebrae; this complication appeared after a partial enucleation of a vestibular schwannoma (VS) with subsequent radiation treatment and second operation with total VS resection. PMID:27597915

  10. Massive Cerebrospinal Fluid Leak of the Temporal Bone.

    PubMed

    Iannella, Giannicola; Manno, Alessandra; Pasqualitto, Emanuela; Ciofalo, Andrea; Angeletti, Diletta; Pasquariello, Benedetta; Magliulo, Giuseppe

    2016-01-01

    Cerebrospinal fluid (CSF) leakage of the temporal bone region is defined as abnormal communications between the subarachnoidal space and the air-containing spaces of the temporal bone. CSF leak remains one of the most frequent complications after VS surgery. Radiotherapy is considered a predisposing factor for development of temporal bone CSF leak because it may impair dural repair mechanisms, thus causing inadequate dural sealing. The authors describe the case of a 47-year-old man with a massive effusion of CSF which extended from the posterior and lateral skull base to the first cervical vertebrae; this complication appeared after a partial enucleation of a vestibular schwannoma (VS) with subsequent radiation treatment and second operation with total VS resection. PMID:27597915

  11. A semiparametric spatio-temporal model for solar irradiance data

    DOE PAGESBeta

    Patrick, Joshua D.; Harvill, Jane L.; Hansen, Clifford W.

    2016-03-01

    Here, we evaluate semiparametric spatio-temporal models for global horizontal irradiance at high spatial and temporal resolution. These models represent the spatial domain as a lattice and are capable of predicting irradiance at lattice points, given data measured at other lattice points. Using data from a 1.2 MW PV plant located in Lanai, Hawaii, we show that a semiparametric model can be more accurate than simple interpolation between sensor locations. We investigate spatio-temporal models with separable and nonseparable covariance structures and find no evidence to support assuming a separable covariance structure. These results indicate a promising approach for modeling irradiance atmore » high spatial resolution consistent with available ground-based measurements. Moreover, this kind of modeling may find application in design, valuation, and operation of fleets of utility-scale photovoltaic power systems.« less

  12. Stable processing with unstable plasmas?

    NASA Astrophysics Data System (ADS)

    Benjamin, Neil

    2004-09-01

    Plasmas are employed for materials processing over a very wide range of conditions. For typical etch applications, these include plasmas generated in various ways with RF at various frequencies and power levels ranging from 100W up to 10000W. Mixed gas chemistries are used, at pressures ranging from mTorr to Torr, with multiple, often electron-attaching species present in significant proportions. These complex conditions are typically produced in production reactors that are hardly optimal for diagnostic access, so this is not a recipe for a quiescent lab plasma that may be conveniently studied. Inevitably a range of plasma instabilities and other unstable conditions may be encountered, often without immediate detection, as one spans the operating space. These unstable conditions may range from internal well known linear and quasi-linear plasma instabilities1, 2 to gross non-linear relaxation oscillations3, 4, 5, parametric drifts and even plasma extinguishment. Many of these phenomena involve strong interactions with the materials being processed and the external hardware that supports the reactor module operation. We will discuss certain questions: how may one observe such conditions (if you can't see it, does it matter from the processing perspective?); is it advisable to continue processing regardless; what might the consequences be, good or bad, and how they may be controlled6? 1) T. H. Stix, Waves in Plasmas, American Institute of Physics, New York (1992), and The Theory of Plasma Waves, McGraw-Hill (1962). 2) N. Krall and A. Trivelpiece, Principles of Plasma Physics, McGraw-Hill (1973). 3) M. Tuszewski, J. App. Phys., 79 8967 (1996) 4) M. A. Lieberman et. al., Appl. Phys. Lett. 75, 3617 (1999) 5) A. M. Marakhtanov et..al., J. Vac. Sci. Tech. A, 21 1864 (2003) and references therein. 6) D.L.Goodman and N. M. P. Benjamin, J. Phys. D, 36 2845 (2003).

  13. Spatio-Temporal Oscillations in Predator-Prey Systems

    NASA Astrophysics Data System (ADS)

    Tomé, T.; de Carvalho, K. Cristina

    2005-10-01

    In recent years a particularly great effort has been made to understand the role of space given by a spatial structure and local interactions in the characterization of the dynamics of competing biological species. Irreversible stochastic lattice models have been studied to mimic predator-prey systems with Markovian local rules based in the Lotka-Volterra model. One of the problems being studied is the stability of the temporal oscillations of the population of two-species systems-whether they are synchronized. Here we study the temporal oscillations of a two-species system by considering two probabilistic cellular automata defined in regular lattices where each site can be in three states: empty, occupied by a prey, or occupied by a predator. One of them, the isotropic model, has local rules similar to those of the contact process and try to mimic the Lotka-Volterra model mechanisms. The other automaton, the anisotropic model, is based in rules that are similar to the isotropic model, but a anisotropic neighborhood is considered. This model was introduced to explore the effect of spatial anisotropy in temporal oscillations. In fact, it has been pointed out that temporally periodic states can be stable in spatial anisotropic irreversible systems whose anisotropy is exploited conveniently. We show Monte Carlo simulations performed on square lattices for both automata. Our results indicate that, in the thermodynamic limit, oscillations can occur only at a local level, even in the anisotropic model. We observe that for given sets of control parameters a spatio-temporal oscillation occurs in the system. These structures are analyzed.

  14. Connecting laboratory behavior to field function through stable isotope analysis.

    PubMed

    Glon, Mael G; Larson, Eric R; Pangle, Kevin L

    2016-01-01

    Inherent difficulties of tracking and observing organisms in the field often leave researchers with no choice but to conduct behavioral experiments under laboratory settings. However, results of laboratory experiments do not always translate accurately to natural conditions. A fundamental challenge in ecology is therefore to scale up from small area and short-duration laboratory experiments to large areas and long durations over which ecological processes generally operate. In this study, we propose that stable isotope analysis may be a tool that can link laboratory behavioral observations to past field interactions or function of individual organisms. We conducted laboratory behavioral assays to measure dominance of invasive rusty crayfish, Orconectes rusticus, and used stable isotope analysis to hindcast trophic positions of these crayfish under preceding natural conditions. We hypothesized that more dominant crayfish in our assays would have higher trophic positions if dominance were related to competitive ability or willingness to pursue high-risk, high-reward prey. We did not find a relationship between crayfish dominance and trophic position, and therefore infer that laboratory dominance of crayfish may not necessarily relate to their ecology in the field. However, this is to our knowledge the first attempt to directly relate laboratory behavior to field performance via stable isotope analysis. We encourage future studies to continue to explore a possible link between laboratory and field behavior via stable isotope analysis, and propose several avenues to do so. PMID:27077010

  15. Connecting laboratory behavior to field function through stable isotope analysis

    PubMed Central

    Larson, Eric R.; Pangle, Kevin L.

    2016-01-01

    Inherent difficulties of tracking and observing organisms in the field often leave researchers with no choice but to conduct behavioral experiments under laboratory settings. However, results of laboratory experiments do not always translate accurately to natural conditions. A fundamental challenge in ecology is therefore to scale up from small area and short-duration laboratory experiments to large areas and long durations over which ecological processes generally operate. In this study, we propose that stable isotope analysis may be a tool that can link laboratory behavioral observations to past field interactions or function of individual organisms. We conducted laboratory behavioral assays to measure dominance of invasive rusty crayfish, Orconectes rusticus, and used stable isotope analysis to hindcast trophic positions of these crayfish under preceding natural conditions. We hypothesized that more dominant crayfish in our assays would have higher trophic positions if dominance were related to competitive ability or willingness to pursue high-risk, high-reward prey. We did not find a relationship between crayfish dominance and trophic position, and therefore infer that laboratory dominance of crayfish may not necessarily relate to their ecology in the field. However, this is to our knowledge the first attempt to directly relate laboratory behavior to field performance via stable isotope analysis. We encourage future studies to continue to explore a possible link between laboratory and field behavior via stable isotope analysis, and propose several avenues to do so. PMID:27077010

  16. Relentful Strategic Reasoning in Alternating-Time Temporal Logic

    NASA Astrophysics Data System (ADS)

    Mogavero, Fabio; Murano, Aniello; Vardi, Moshe Y.

    Temporal logics are a well investigated formalism for the specification, verification, and synthesis of reactive systems. Within this family, alternating temporal logic, Atl *, has been introduced as a useful generalization of classical linear- and branching-time temporal logics by allowing temporal operators to be indexed by coalitions of agents. Classically, temporal logics are memoryless: once a path in the computation tree is quantified at a given node, the computation that has led to that node is forgotten. Recently, mCtl * has been defined as a memoryful variant of Ctl *, where path quantification is memoryful. In the context of multi-agent planning, memoryful quantification enables agents to "relent" and change their goals and strategies depending on their past history. In this paper, we define mAtl *, a memoryful extension of Atl *, in which a formula is satisfied at a certain node of a path by taking into account both the future and the past. We study the expressive power of mAtl *, its succinctness, as well as related decision problems. We also investigate the relationship between memoryful quantification and past modalities and show their equivalence. We show that both the memoryful and the past extensions come without any computational price; indeed, we prove that both the satisfiability and the model-checking problems are 2ExpTime-Complete, as they are for Atl *.

  17. Scaling of processes shaping the clonal dynamics and genetic mosaic of seagrasses through temporal genetic monitoring.

    PubMed

    Becheler, R; Benkara, E; Moalic, Y; Hily, C; Arnaud-Haond, S

    2014-02-01

    Theoretically, the dynamics of clonal and genetic diversities of clonal plant populations are strongly influenced by the competition among clones and rate of seedling recruitment, but little empirical assessment has been made of such dynamics through temporal genetic surveys. We aimed to quantify 3 years of evolution in the clonal and genetic composition of Zostera marina meadows, comparing parameters describing clonal architecture and genetic diversity at nine microsatellite markers. Variations in clonal structure revealed a decrease in the evenness of ramet distribution among genets. This illustrates the increasing dominance of some clonal lineages (multilocus lineages, MLLs) in populations. Despite the persistence of these MLLs over time, genetic differentiation was much stronger in time than in space, at the local scale. Contrastingly with the short-term evolution of clonal architecture, the patterns of genetic structure and genetic diversity sensu stricto (that is, heterozygosity and allelic richness) were stable in time. These results suggest the coexistence of (i) a fine grained (at the scale of a 20 × 30 m quadrat) stable core of persistent genets originating from an initial seedling recruitment and developing spatial dominance through clonal elongation; and (ii) a local (at the scale of the meadow) pool of transient genets subjected to annual turnover. This simultaneous occurrence of initial and repeated recruitment strategies highlights the different spatial scales at which distinct evolutionary drivers and mating systems (clonal competition, clonal growth, propagule dispersal and so on) operate to shape the dynamics of populations and the evolution of polymorphism in space and time. PMID:24022498

  18. Scaling of processes shaping the clonal dynamics and genetic mosaic of seagrasses through temporal genetic monitoring

    PubMed Central

    Becheler, R; Benkara, E; Moalic, Y; Hily, C; Arnaud-Haond, S

    2014-01-01

    Theoretically, the dynamics of clonal and genetic diversities of clonal plant populations are strongly influenced by the competition among clones and rate of seedling recruitment, but little empirical assessment has been made of such dynamics through temporal genetic surveys. We aimed to quantify 3 years of evolution in the clonal and genetic composition of Zostera marina meadows, comparing parameters describing clonal architecture and genetic diversity at nine microsatellite markers. Variations in clonal structure revealed a decrease in the evenness of ramet distribution among genets. This illustrates the increasing dominance of some clonal lineages (multilocus lineages, MLLs) in populations. Despite the persistence of these MLLs over time, genetic differentiation was much stronger in time than in space, at the local scale. Contrastingly with the short-term evolution of clonal architecture, the patterns of genetic structure and genetic diversity sensu stricto (that is, heterozygosity and allelic richness) were stable in time. These results suggest the coexistence of (i) a fine grained (at the scale of a 20 × 30 m quadrat) stable core of persistent genets originating from an initial seedling recruitment and developing spatial dominance through clonal elongation; and (ii) a local (at the scale of the meadow) pool of transient genets subjected to annual turnover. This simultaneous occurrence of initial and repeated recruitment strategies highlights the different spatial scales at which distinct evolutionary drivers and mating systems (clonal competition, clonal growth, propagule dispersal and so on) operate to shape the dynamics of populations and the evolution of polymorphism in space and time. PMID:24022498

  19. Temporal chaos in Boussinesq magnetoconvection

    SciTech Connect

    Bekki, Naoaki; Moriguchi, Hirofumi

    2007-01-15

    Two-dimensional Boussinesq magnetoconvection with idealized stress-free boundary conditions is numerically investigated in order to make clear the difference between chaos and turbulence. It is shown that the long-term behavior of magnetoconvection exhibits spatially coherent and temporally chaotic rolls in marked contrast to highly turbulent fluids. It is also shown that heat transport becomes larger anomalously when the polarity reversal of the magnetic field occurs intermittently in the case of temporally chaotic magnetoconvection. It is found that the Poincare return map of the relative maximum temperature fluctuation of partial differential equations as a function of the preceding maximum resembles the famous Lorenz plot in narrow rolls of magnetoconvection. The chaotic behavior of narrow rolls for individual parameter values robustly persists up to rolls about one fifth as wide as they are high near the codimension-two bifurcation point.

  20. Temporal order judgment in dyslexia.

    PubMed

    Jaśkowski, Piotr; Rusiak, Patrycja

    2008-01-01

    Hari et al. (Brain 174:1373-1380, 2001) demonstrated that dyslexics showed a sluggish attention capture in both visual hemifields. Additionally, they indicated a left-right asymmetry in the perception of temporal order of two visual stimuli (they performed worse than controls only if the stimulus in the left hemifield preceded that in right hemifield). They suggested that a left-sided minineglect is associated with dyslexia. We hypothesized that if a kind of neglect syndrome is responsible for the asymmetry they found, dyslexics should not only show a left-right asymmetry in temporal order judgment of two laterally presented stimuli but also perform equally well as controls when the stimuli are vertically aligned. Our results indicated that in both tasks dyslexics performed generally worse than normal readers. The results suggest that dyslexics suffer from a more general problem of order discrimination. PMID:17028891

  1. Stochastic spatio-temporal modelling with PCRaster Python

    NASA Astrophysics Data System (ADS)

    Karssenberg, D.; Schmitz, O.; de Jong, K.

    2012-04-01

    PCRaster Python is a software framework for building spatio-temporal models of land surface processes (Karssenberg, Schmitz, Salamon, De Jong, & Bierkens, 2010; PCRaster, 2012). Building blocks of models are spatial operations on raster maps, including a large suite of operations for water and sediment routing. These operations, developed in C++, are available to model builders as Python functions. Users create models by combining these functions in a Python script. As construction of large iterative models is often difficult and time consuming for non-specialists in programming, the software comes with a set of Python framework classes that provide control flow for static modelling, temporal modelling, stochastic modelling using Monte Carlo simulation, and data assimilation techniques including the Ensemble Kalman filter and the Particle Filter. A framework for integrating model components with different time steps and spatial discretization is currently available as a prototype (Schmitz, de Jong, & Karssenberg, in review). The software includes routines for visualisation of stochastic spatio-temporal data for prompt, interactive, visualisation of model inputs and outputs. Visualisation techniques include animated maps, time series, probability distributions, and animated maps with exceedance probabilities. The PCRaster Python software is used by researchers from a large range of disciplines, including hydrology, ecology, sedimentology, and land use change studies. Applications include global scale hydrological modelling and error propagation in large-scale land use change models. The software runs on MS Windows and Linux operating systems, and OS X (under development).

  2. Functional Connectome before and following Temporal Lobectomy in Mesial Temporal Lobe Epilepsy.

    PubMed

    Liao, Wei; Ji, Gong-Jun; Xu, Qiang; Wei, Wei; Wang, Jue; Wang, Zhengge; Yang, Fang; Sun, Kangjian; Jiao, Qing; Richardson, Mark P; Zang, Yu-Feng; Zhang, Zhiqiang; Lu, Guangming

    2016-01-01

    As mesial temporal lobe epilepsy (mTLE) has been recognized as a network disorder, a longitudinal connectome investigation may shed new light on the understanding of the underlying pathophysiology related to distinct surgical outcomes. Resting-state functional MRI data was acquired from mTLE patients before (n = 37) and after (n = 24) anterior temporal lobectomy. According to surgical outcome, patients were classified as seizure-free (SF, n = 14) or non-seizure-free (NSF, n = 10). First, we found higher network resilience to targeted attack on topologically central nodes in the SF group compared to the NSF group, preoperatively. Next, a two-way mixed analysis of variance with between-subject factor 'outcome' (SF vs. NSF) and within-subject factor 'treatment' (pre-operation vs. post-operation) revealed divergent dynamic reorganization in nodal topological characteristics between groups, in the temporoparietal junction and its connection with the ventral prefrontal cortex. We also correlated the network damage score (caused by surgical resection) with postsurgical brain function, and found that the damage score negatively correlated with postoperative global and local parallel information processing. Taken together, dynamic connectomic architecture provides vital information for selecting surgical candidates and for understanding brain recovery mechanisms following epilepsy surgery. PMID:27001417

  3. Functional Connectome before and following Temporal Lobectomy in Mesial Temporal Lobe Epilepsy

    PubMed Central

    Liao, Wei; Ji, Gong-Jun; Xu, Qiang; Wei, Wei; Wang, Jue; Wang, Zhengge; Yang, Fang; Sun, Kangjian; Jiao, Qing; Richardson, Mark P.; Zang, Yu-Feng; Zhang, Zhiqiang; Lu, Guangming

    2016-01-01

    As mesial temporal lobe epilepsy (mTLE) has been recognized as a network disorder, a longitudinal connectome investigation may shed new light on the understanding of the underlying pathophysiology related to distinct surgical outcomes. Resting-state functional MRI data was acquired from mTLE patients before (n = 37) and after (n = 24) anterior temporal lobectomy. According to surgical outcome, patients were classified as seizure-free (SF, n = 14) or non-seizure-free (NSF, n = 10). First, we found higher network resilience to targeted attack on topologically central nodes in the SF group compared to the NSF group, preoperatively. Next, a two-way mixed analysis of variance with between-subject factor ‘outcome’ (SF vs. NSF) and within-subject factor ‘treatment’ (pre-operation vs. post-operation) revealed divergent dynamic reorganization in nodal topological characteristics between groups, in the temporoparietal junction and its connection with the ventral prefrontal cortex. We also correlated the network damage score (caused by surgical resection) with postsurgical brain function, and found that the damage score negatively correlated with postoperative global and local parallel information processing. Taken together, dynamic connectomic architecture provides vital information for selecting surgical candidates and for understanding brain recovery mechanisms following epilepsy surgery. PMID:27001417

  4. Inflated Soft Actuators with Reversible Stable Deformations.

    PubMed

    Hines, Lindsey; Petersen, Kirstin; Sitti, Metin

    2016-05-01

    Most soft robotic systems are currently dependent on bulky compressors or pumps. A soft actuation method is presented combining hyperelastic membranes and dielectric elastomer actuators to switch between stable deformations of sealed chambers. This method is capable of large repeatable deformations, and has a number of stable states proportional to the number of actuatable membranes in the chamber. PMID:27008455

  5. Blood feeding behavior of the stable fly

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable fly is a fly that looks similar to a house fly but both sexes are blood feeders. Blood is required for successful fertilization and development of eggs. Bites are painful but there is usually no pain after the fly stops feeding. The stable fly is a persistent feeder and will continue trying t...

  6. Effective Visualization of Temporal Ensembles.

    PubMed

    Hao, Lihua; Healey, Christopher G; Bass, Steffen A

    2016-01-01

    An ensemble is a collection of related datasets, called members, built from a series of runs of a simulation or an experiment. Ensembles are large, temporal, multidimensional, and multivariate, making them difficult to analyze. Another important challenge is visualizing ensembles that vary both in space and time. Initial visualization techniques displayed ensembles with a small number of members, or presented an overview of an entire ensemble, but without potentially important details. Recently, researchers have suggested combining these two directions, allowing users to choose subsets of members to visualization. This manual selection process places the burden on the user to identify which members to explore. We first introduce a static ensemble visualization system that automatically helps users locate interesting subsets of members to visualize. We next extend the system to support analysis and visualization of temporal ensembles. We employ 3D shape comparison, cluster tree visualization, and glyph based visualization to represent different levels of detail within an ensemble. This strategy is used to provide two approaches for temporal ensemble analysis: (1) segment based ensemble analysis, to capture important shape transition time-steps, clusters groups of similar members, and identify common shape changes over time across multiple members; and (2) time-step based ensemble analysis, which assumes ensemble members are aligned in time by combining similar shapes at common time-steps. Both approaches enable users to interactively visualize and analyze a temporal ensemble from different perspectives at different levels of detail. We demonstrate our techniques on an ensemble studying matter transition from hadronic gas to quark-gluon plasma during gold-on-gold particle collisions. PMID:26529728

  7. Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry

    SciTech Connect

    Wilcox, R.; Byrd, J. M.; Doolittle, L.; Huang, G.; Staples, J. W.

    2010-01-02

    New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase.

  8. Temporal ecology in the Anthropocene.

    PubMed

    Wolkovich, E M; Cook, B I; McLauchlan, K K; Davies, T J

    2014-11-01

    Two fundamental axes - space and time - shape ecological systems. Over the last 30 years spatial ecology has developed as an integrative, multidisciplinary science that has improved our understanding of the ecological consequences of habitat fragmentation and loss. We argue that accelerating climate change - the effective manipulation of time by humans - has generated a current need to build an equivalent framework for temporal ecology. Climate change has at once pressed ecologists to understand and predict ecological dynamics in non-stationary environments, while also challenged fundamental assumptions of many concepts, models and approaches. However, similarities between space and time, especially related issues of scaling, provide an outline for improving ecological models and forecasting of temporal dynamics, while the unique attributes of time, particularly its emphasis on events and its singular direction, highlight where new approaches are needed. We emphasise how a renewed, interdisciplinary focus on time would coalesce related concepts, help develop new theories and methods and guide further data collection. The next challenge will be to unite predictive frameworks from spatial and temporal ecology to build robust forecasts of when and where environmental change will pose the largest threats to species and ecosystems, as well as identifying the best opportunities for conservation. PMID:25199649

  9. Visual adjustments to temporal blur

    NASA Astrophysics Data System (ADS)

    Bilson, Aaron C.; Mizokami, Yoko; Webster, Michael A.

    2005-10-01

    After observers have adapted to an edge that is spatially blurred or sharpened, a focused edge appears too sharp or blurred, respectively. These adjustments to blur may play an important role in calibrating spatial sensitivity. We examined whether similar adjustments influence the perception of temporal edges, by measuring the appearance of a step change in the luminance of a uniform field after adapting to blurred or sharpened transitions. Stimuli were square-wave alternations (at 1 to 8 Hz) filtered by changing the slope of the amplitude spectrum. A two-alternative-forced-choice task was used to adjust the slope until it appeared as a step change, or until it matched the perceived transitions in a reference stimulus. Observers could accurately set the waveform to a square wave, but only at the slower alternation rates. However, these settings were strongly biased by prior adaptation to filtered stimuli, or when the stimuli were viewed within temporally filtered surrounds. Control experiments suggest that the latter induction effects result directly from the temporal blur and are not simply a consequence of brightness induction in the fields. These results suggest that adaptation and induction adjust visual coding so that images are focused not only in space but also in time.

  10. Finding Mutual Exclusion Invariants in Temporal Planning Domains

    NASA Technical Reports Server (NTRS)

    Bernardini, Sara; Smith, David E.

    2011-01-01

    We present a technique for automatically extracting temporal mutual exclusion invariants from PDDL2.2 planning instances. We first identify a set of invariant candidates by inspecting the domain and then check these candidates against properties that assure invariance. If these properties are violated, we show that it is sometimes possible to refine a candidate by adding additional propositions and turn it into a real invariant. Our technique builds on other approaches to invariant synthesis presented in the literature, but departs from their limited focus on instantaneous discrete actions by addressing temporal and numeric domains. To deal with time, we formulate invariance conditions that account for both the entire structure of the operators (including the conditions, rather than just the effects) and the possible interactions between operators. As a result, we construct a technique that is not only capable of identifying invariants for temporal domains, but is also able to find a broader set of invariants for non-temporal domains than the previous techniques.

  11. Cubic map algebra functions for spatio-temporal analysis

    USGS Publications Warehouse

    Mennis, J.; Viger, R.; Tomlin, C.D.

    2005-01-01

    We propose an extension of map algebra to three dimensions for spatio-temporal data handling. This approach yields a new class of map algebra functions that we call "cube functions." Whereas conventional map algebra functions operate on data layers representing two-dimensional space, cube functions operate on data cubes representing two-dimensional space over a third-dimensional period of time. We describe the prototype implementation of a spatio-temporal data structure and selected cube function versions of conventional local, focal, and zonal map algebra functions. The utility of cube functions is demonstrated through a case study analyzing the spatio-temporal variability of remotely sensed, southeastern U.S. vegetation character over various land covers and during different El Nin??o/Southern Oscillation (ENSO) phases. Like conventional map algebra, the application of cube functions may demand significant data preprocessing when integrating diverse data sets, and are subject to limitations related to data storage and algorithm performance. Solutions to these issues include extending data compression and computing strategies for calculations on very large data volumes to spatio-temporal data handling.

  12. Spatial-temporal database model based on geodatabase

    NASA Astrophysics Data System (ADS)

    Zhu, Hongmei; Luo, Yu

    2009-10-01

    Entities in the real world have non-spatial attributes, as well as spatial and temporal features. A spatial-temporal data model aims at describing appropriately these intrinsic characteristics within the entities and model them on a conceptual level so that the model can present both static information and dynamic information that occurs over time. In this paper, we devise a novel spatial-temporal data model which is based on Geodatabase. The model employs object-oriented analysis method, combining object concept with event. The entity is defined as a feature class encapsulating attributes and operations. The operations detect change and store the changes automatically in a historic database in Geodatabase. Furthermore, the model takes advantage of the existing strengths of the relational database at the bottom level of Geodatabase, such as trigger and constraint, to monitor events on the attributes or locations and respond to the events correctly. A case of geographic database for Kunming municipal sewerage geographic information system is implemented by the model. The database reveals excellent performance on managing data and tracking the details of change. It provides a perfect data platform for querying, recurring history and predicting the trend of future. The instance demonstrates the spatial-temporal data model is efficient and practicable.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-04-01

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

  15. Finding temporal order in discharge summaries.

    PubMed

    Bramsen, Philip; Deshpande, Pawan; Lee, Yoong Keok; Barzilay, Regina

    2006-01-01

    A method for automatic analysis of time-oriented clinical narratives would be of significant practical import for medical decision making, data modeling and biomedical research. This paper proposes a robust corpus-based approach for temporal analysis of medical discharge summaries. We characterize temporal organization of clinical narratives in terms of temporal segments and their ordering. We consider a temporal segment to be a fragment of text that does not exhibit abrupt changes in temporal focus. Our method derives temporal order based on a range of linguistic and contextual features that are integrated in a supervised machine-learning framework. Our learning method achieves 83% F-measure in tempo-ral segmentation, and 78.3% accuracy in inferring pairwise temporal relations. PMID:17238307

  16. The Chronus II temporal database mediator.

    PubMed Central

    O'Connor, Martin J.; Tu, Samson W.; Musen, Mark A.

    2002-01-01

    Clinical databases typically contain a significant amount of temporal information. This information is often crucial in medical decision-support systems. Although temporal queries are common in clinical systems, the medical informatics field has no standard means for representing or querying temporal data. Over the past decade, the temporal database community has made a significant amount of progress in temporal systems. Much of this research can be applied to clinical database systems. This paper outlines a temporal database mediator called Chronus II. Chronus II extends the standard relational model and the SQL query language to support temporal queries. It provides an expressive general-purpose temporal query language that is tuned to the querying requirements of clinical decision support systems. This paper describes how we have used Chronus II to tackle a variety of clinical problems in decision support systems developed by our group. PMID:12474882

  17. Classification of battlespace detonations from temporally resolved multi-band imagery and mid-infrared spectra

    NASA Astrophysics Data System (ADS)

    Dills, Anthony N.

    The classification of battlespace detonations, specifically the determination of munitions type and size using temporal and spectral features, has been studied using near-infrared (NIR) and multi-color visible wavelength imagers. Key features from the time dependence of fireball size are identified for discriminating various types and sizes of detonation flashes. The five classes include three weights of trinitrotoluene (TNT) and two weights of an enhanced mixture, all of which are uncased and detonated with 10% C4. Using Fisher linear discriminant techniques, features are projected onto a line such that the projected points are maximally clustered for the different classes of detonations. Bayesian decision boundaries are then established on class-conditional probability densities. Feature saliency and stability are determined by selecting features that best discriminate while requiring low variations in class-conditional probability densities and high performance in independent testing. The most important and stable feature is the time to the maximum fireball area in the near-infrared wavelength band. Overall, the features related to the time to peak (tmp) of the fireball provide the best classification for each of three a priori conditions. This feature correctly discriminates between TNT and ENE about 90% of the time, whether weight is known or not. The associated class-conditional probability densities separate the two classes with a Fisher ratio of 2.9 and an area under the receiver operating characteristic, AROC, of 0.992. Also, tmp achieves approximately 60% success rate at discerning both weight and type.

  18. Temporal succession in carbon incorporation from macromolecules by particle-attached bacteria in marine microcosms.

    PubMed

    Mayali, Xavier; Stewart, Benjamin; Mabery, Shalini; Weber, Peter K

    2016-02-01

    We investigated bacterial carbon assimilation from stable isotope-labelled macromolecular substrates (proteins; lipids; and two types of polysaccharides, starch and cellobiose) while attached to killed diatom detrital particles during laboratory microcosms incubated for 17 days. Using Chip-SIP (secondary ion mass spectrometry analysis of RNA microarrays), we identified generalist operational taxonomic units (OTUs) from the Gammaproteobacteria, belonging to the genera Colwellia, Glaciecola, Pseudoalteromonas and Rheinheimera, and from the Bacteroidetes, genera Owenweeksia and Maribacter, that incorporated the four tested substrates throughout the incubation period. Many of these OTUs exhibited the highest isotope incorporation relative to the others, indicating that they were likely the most active. Additional OTUs from the Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria exhibited generally (but not always) lower activity and did not incorporate all tested substrates at all times, showing species succession in organic carbon incorporation. We also found evidence to suggest that both generalist and specialist OTUs changed their relative substrate incorporation over time, presumably in response to changing substrate availability as the particles aged. This pattern was demonstrated by temporal succession from relatively higher starch incorporation early in the incubations, eventually switching to higher cellobiose incorporation after 2 weeks. PMID:26525158

  19. Ground Operations

    NASA Technical Reports Server (NTRS)

    Eastman, Randy

    2000-01-01

    The contents include: 1) Integrated Space Transportation; 2) Fourth Generation Reusable Launch Vehicle (RLV) Research; 3) Ground Operations; 4) Ground Operations Technologies; 5) Sensors; and 6) Umbilicals. This paper is presented in viewgraph form.

  20. Your alliances are too stable.

    PubMed

    Ernst, David; Bamford, James

    2005-06-01

    A 2004 McKinsey survey of more than 30 companies reveals that at least 70% of them have major alliances that are underperforming and in need of restructuring. Moreover, JVs that broaden or otherwise adjust their scope have a 79% success rate, versus 33% for ventures that remain essentially unchanged. Yet most firms don't routinely evaluate the need to overhaul their alliances or intervene to correct performance problems. That means corporations are missing huge opportunities: By revamping just one large alliance, a company can generate 100 million dololars to 300 million dollars in extra income a year. Here's how to unlock more value from alliances: (1) Launch the process. Don't wait until your venture is in the middle of a crisis; regularly scan your major alliances to determine which need restructuring. Once you've targeted one, designate a restructuring team and find a senior sponsor to push the process along. Then delineate the scope of the team's work. (2) Diagnose performance. Evaluate the venture on the following performance dimensions: ownership and financials, strategy, operations, governance, and organization and talent. Identify the root causes of the venture's problems, not just the symptoms, and estimate how much each problem is costing the company. (3) Generate restructuring options. Based on the diagnosis, decide whether to fix, grow, or exit the alliance. Assuming the answer is fix or grow, determine whether fundamental or incremental changes are needed, using the five performance dimensions above as a framework. Then assemble three or four packages of restructuring options, test them with shareholders, and gain parents' approval. (4) Execute the changes. Embark on a widespread and consistent communication effort, building support among executives in the JV and the parent companies. So the process stays on track, assign accountability to certain groups or individuals. PMID:15938444

  1. Lateralized Temporal Order Judgement in Dyslexia

    ERIC Educational Resources Information Center

    Liddle, Elizabeth B.; Jackson, Georgina M.; Rorden, Chris; Jackson, Stephen R.

    2009-01-01

    Temporal and spatial attentional deficits in dyslexia were investigated using a lateralized visual temporal order judgment (TOJ) paradigm that allowed both sensitivity to temporal order and spatial attentional bias to be measured. Findings indicate that adult participants with a positive screen for dyslexia were significantly less sensitive to the…

  2. Temporal Phenomena in the Korean Conjunctive Constructions

    ERIC Educational Resources Information Center

    Kim, Dongmin

    2015-01-01

    The goal of this study is to characterize the temporal phenomena in the Korean conjunctive constructions. These constructions consist of three components: a verbal stem, a clause medial temporal suffix, and a clause terminal suffix. This study focuses on both the temporality of the terminal connective suffixes and the grammatical meanings of the…

  3. Environmental controls on stable isotope ratios in New Zealand Podocarpaceae: Implications for palaeoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Brett, Marianne J.; Baldini, James U. L.; Gröcke, Darren R.

    2014-09-01

    Stable isotope ratios of various proxies are widely used for palaeoclimate reconstruction, and it is often assumed that isotope ratios reflect vegetation abundance or type. However, very little research exists on the isotopic equilibration of extant biomes under variable environmental conditions. In this study, carbon and oxygen isotope ratios from leaves of various Podocarpaceae genera, endemic to New Zealand, are linked to environmental parameters from the Land Environments New Zealand model. The dominant influence on stable isotope ratios within the majority of Podocarpaceae studied here is vapour pressure deficit (VPD). A simple latitudinal trend does not exist, and neither temperature nor rainfall (decoupled from VPD) controls the stable isotope ratios. The results suggest that modern spatial heterogeneity in VPD affects the stable isotope values of vegetation, and that historic VPD variability would change the stable isotope ratios of Podocarpaceae without necessitating a change in vegetation type, density, or productivity. This represents an alternative model for temporal isotope change within geochemical proxies and reinforces the need for increased stable isotopic research in modern plant ecosystems to better understand modern, and eventually palaeoclimatic processes affecting the terrestrial biosphere.

  4. Temporal Stability of Genetic Structure in a Mesopelagic Copepod.

    PubMed

    Goetze, Erica; Andrews, Kimberly R; Peijnenburg, Katja T C A; Portner, Elan; Norton, Emily L

    2015-01-01

    Although stochasticity in oceanographic conditions is known to be an important driver of temporal genetic change in many marine species, little is known about whether genetically distinct plankton populations can persist in open ocean habitats. A prior study demonstrated significant population genetic structure among oceanic gyres in the mesopelagic copepod Haloptilus longicornis in both the Atlantic and Pacific Oceans, and we hypothesized that populations within each gyre represent distinct gene pools that persist over time. We tested this expectation through basin-scale sampling across the Atlantic Ocean in 2010 and 2012. Using both mitochondrial (mtCOII) and microsatellite markers (7 loci), we show that the genetic composition of populations was stable across two years in both the northern and southern subtropical gyres. Genetic variation in this species was partitioned among ocean gyres (FCT = 0.285, P < 0.0001 for mtCOII, FCT = 0.013, P < 0.0001 for microsatellites), suggesting strong spatial population structure, but no significant partitioning was found among sampling years. This temporal persistence of population structure across a large geographic scale was coupled with chaotic genetic patchiness at smaller spatial scales, but the magnitude of genetic differentiation was an order of magnitude lower at these smaller scales. Our results demonstrate that genetically distinct plankton populations persist over time in highly-dispersive open ocean habitats, and this is the first study to rigorously test for temporal stability of large scale population structure in the plankton. PMID:26302332

  5. Temporal Stability of Genetic Structure in a Mesopelagic Copepod

    PubMed Central

    Goetze, Erica; Andrews, Kimberly R.; Peijnenburg, Katja T. C. A.; Portner, Elan; Norton, Emily L.

    2015-01-01

    Although stochasticity in oceanographic conditions is known to be an important driver of temporal genetic change in many marine species, little is known about whether genetically distinct plankton populations can persist in open ocean habitats. A prior study demonstrated significant population genetic structure among oceanic gyres in the mesopelagic copepod Haloptilus longicornis in both the Atlantic and Pacific Oceans, and we hypothesized that populations within each gyre represent distinct gene pools that persist over time. We tested this expectation through basin-scale sampling across the Atlantic Ocean in 2010 and 2012. Using both mitochondrial (mtCOII) and microsatellite markers (7 loci), we show that the genetic composition of populations was stable across two years in both the northern and southern subtropical gyres. Genetic variation in this species was partitioned among ocean gyres (FCT = 0.285, P < 0.0001 for mtCOII, FCT = 0.013, P < 0.0001 for microsatellites), suggesting strong spatial population structure, but no significant partitioning was found among sampling years. This temporal persistence of population structure across a large geographic scale was coupled with chaotic genetic patchiness at smaller spatial scales, but the magnitude of genetic differentiation was an order of magnitude lower at these smaller scales. Our results demonstrate that genetically distinct plankton populations persist over time in highly-dispersive open ocean habitats, and this is the first study to rigorously test for temporal stability of large scale population structure in the plankton. PMID:26302332

  6. Rational temporal predictions can underlie apparent failures to delay gratification.

    PubMed

    McGuire, Joseph T; Kable, Joseph W

    2013-04-01

    An important category of seemingly maladaptive decisions involves failure to postpone gratification. A person pursuing a desirable long-run outcome may abandon it in favor of a short-run alternative that has been available all along. Here we present a theoretical framework in which this seemingly irrational behavior emerges from stable preferences and veridical judgments. Our account recognizes that decision makers generally face uncertainty regarding the time at which future outcomes will materialize. When timing is uncertain, the value of persistence depends crucially on the nature of a decision maker's prior temporal beliefs. Certain forms of temporal beliefs imply that a delay's predicted remaining length increases as a function of time already waited. In this type of situation, the rational, utility-maximizing strategy is to persist for a limited amount of time and then give up. We show empirically that people's explicit predictions of remaining delay lengths indeed increase as a function of elapsed time in several relevant domains, implying that temporal judgments offer a rational basis for limiting persistence. We then develop our framework into a simple working model and show how it accounts for individual differences in a laboratory task (the well-known "marshmallow test"). We conclude that delay-of-gratification failure, generally viewed as a manifestation of limited self-control capacity, can instead arise as an adaptive response to the perceived statistics of one's environment. PMID:23458085

  7. Rational temporal predictions can underlie apparent failures to delay gratification

    PubMed Central

    McGuire, Joseph T.; Kable, Joseph W.

    2013-01-01

    An important category of seemingly maladaptive decisions involves failure to postpone gratification. A person pursuing a desirable long-run outcome may abandon it in favor of a short-run alternative that has been available all along. Here we present a theoretical framework in which this seemingly irrational behavior emerges from stable preferences and veridical judgments. Our account recognizes that decision makers generally face uncertainty regarding the time at which future outcomes will materialize. When timing is uncertain, the value of persistence depends crucially on the nature of a decision-maker’s prior temporal beliefs. Certain forms of temporal beliefs imply that a delay’s predicted remaining length increases as a function of time already waited. In this type of situation, the rational, utility-maximizing strategy is to persist for a limited amount of time and then give up. We show empirically that people’s explicit predictions of remaining delay lengths indeed increase as a function of elapsed time in several relevant domains, implying that temporal judgments offer a rational basis for limiting persistence. We then develop our framework into a simple working model and show how it accounts for individual differences in a laboratory task (the well-known “marshmallow test”). We conclude that delay-of-gratification failure, generally viewed as a manifestation of limited self-control capacity, can instead arise as an adaptive response to the perceived statistics of one’s environment. PMID:23458085

  8. Vapor-deposited glasses of methyl-m-toluate: How uniform is stable glass transformation?

    NASA Astrophysics Data System (ADS)

    Tylinski, M.; Sepúlveda, A.; Walters, Diane M.; Chua, Y. Z.; Schick, C.; Ediger, M. D.

    2015-12-01

    AC chip nanocalorimetry is used to characterize vapor-deposited glasses of methyl-m-toluate (MMT). Physical vapor deposition can prepare MMT glasses that have lower heat capacity and significantly higher kinetic stability compared to liquid-cooled glasses. When heated, highly stable MMT glasses transform into the supercooled liquid via propagating fronts. We present the first quantitative analysis of the temporal and spatial uniformities of these transformation fronts. The front velocity varies by less than 4% over the duration of the transformation. For films 280 nm thick, the transformation rates at different spatial positions in the film differ by about 25%; this quantity may be related to spatially heterogeneous dynamics in the stable glass. Our characterization of the kinetic stability of MMT stable glasses extends previous dielectric experiments and is in excellent agreement with these results.

  9. Vapor-deposited glasses of methyl-m-toluate: How uniform is stable glass transformation?

    PubMed

    Tylinski, M; Sepúlveda, A; Walters, Diane M; Chua, Y Z; Schick, C; Ediger, M D

    2015-12-28

    AC chip nanocalorimetry is used to characterize vapor-deposited glasses of methyl-m-toluate (MMT). Physical vapor deposition can prepare MMT glasses that have lower heat capacity and significantly higher kinetic stability compared to liquid-cooled glasses. When heated, highly stable MMT glasses transform into the supercooled liquid via propagating fronts. We present the first quantitative analysis of the temporal and spatial uniformities of these transformation fronts. The front velocity varies by less than 4% over the duration of the transformation. For films 280 nm thick, the transformation rates at different spatial positions in the film differ by about 25%; this quantity may be related to spatially heterogeneous dynamics in the stable glass. Our characterization of the kinetic stability of MMT stable glasses extends previous dielectric experiments and is in excellent agreement with these results. PMID:26723694

  10. Tempered stable Lévy motion and transient super-diffusion

    NASA Astrophysics Data System (ADS)

    Baeumer, Boris; Meerschaert, Mark M.

    2010-03-01

    The space-fractional diffusion equation models anomalous super-diffusion. Its solutions are transition densities of a stable Lévy motion, representing the accumulation of power-law jumps. The tempered stable Lévy motion uses exponential tempering to cool these jumps. A tempered fractional diffusion equation governs the transition densities, which progress from super-diffusive early-time to diffusive late-time behavior. This article provides finite difference and particle tracking methods for solving the tempered fractional diffusion equation with drift. A temporal and spatial second-order Crank-Nicolson method is developed, based on a finite difference formula for tempered fractional derivatives. A new exponential rejection method for simulating tempered Lévy stables is presented to facilitate particle tracking codes.

  11. Turbulence and pollutant transport in urban street canyons under stable stratification: a large-eddy simulation

    NASA Astrophysics Data System (ADS)

    Li, X.

    2014-12-01

    Thermal stratification of the atmospheric surface layer has strong impact on the land-atmosphere exchange of turbulent, heat, and pollutant fluxes. Few studies have been carried out for the interaction of the weakly to moderately stable stratified atmosphere and the urban canopy. This study performs a large-eddy simulation of a modeled street canyon within a weakly to moderately stable atmosphere boundary layer. To better resolve the smaller eddy size resulted from the stable stratification, a higher spatial and temporal resolution is used. The detailed flow structure and turbulence inside the street canyon are analyzed. The relationship of pollutant dispersion and Richardson number of the atmosphere is investigated. Differences between these characteristics and those under neutral and unstable atmosphere boundary layer are emphasized.

  12. Chemodectomas arising in temporal bone structures

    SciTech Connect

    Dickens, W.J.; Million, R.R.; Cassisi, N.J.; Singleton, G.T.

    1982-02-01

    Eighteen patients with chemodectomas arising in temporal bone structures were evaluated and treated at the University of Florida. Seventeen patients have each been followed a minimum of 3 years. Patients were retrospectively staged as having ''local'' or ''advanced'' disease, depending on the presence or absence of bone destruction and/or cranial nerve involvement. Fourteen of the patients received radiation therapy as all or part of their therapy; 6 patients were treated with radiation therapy alone, 3 patients were irradiated immediately postoperatively for residual disease, and 5 patients had radiation therapy for recurrence after operation. They were treated with cobalt-60 radiation with doses ranging from 3760 to 5640 rad. All irradiated patients demonstrated evidence of tumor regression, and none have had tumor recurrence with followup of 3-12 years. Of the 8 patients with cranial nerve paralysis prior to therapy, 5 had return of function of 1 or more cranial nerves. One of 6 patients treated initially with radiation therapy had a complication, while 6 of 8 patients irradiated postoperatively had complications. None of the complications were fatal. Three patients treated by operation for early disease limited to the hypotympanum had the disease controlled for 11-12 years. Guidelines for the selection of initial therapy are discussed.

  13. A GRASS GIS based Spatio-Temporal Algebra for Raster-, 3D Raster- and Vector Time Series Data

    NASA Astrophysics Data System (ADS)

    Leppelt, Thomas; Gebbert, Sören

    2015-04-01

    Enhancing the well known and widely used map algebra proposed by Dr. Charles Dana Tomlin [1] with the time dimension is an ongoing research topic. The efficient processing of large time series of raster, 3D raster and vector datasets, e. g. raster datasets for temperature or precipitations on continental scale, requires a sophisticated spatio-temporal algebra that is capable of handling datasets with different temporal granularities and spatio-temporal extents. With the temporal enabled GRASS GIS [2] and the GRASS GIS Temporal Framework new spatio-temporal data types are available in GRASS GIS 7, called space time datasets. These space time datasets represent time series of raster, 3D raster and vector map layers. Furthermore the temporal framework provides a wide range of functionalities to support the implementation of a temporal algebra. While spatial capabilities of GRASS GIS are used to perform the spatial processing of the time stamped map layers that are registered in a space time dataset, the temporal processing is provided by the GRASS GIS temporal framework that supports time intervals and time instances. Mixing time instance and time intervals as well as gaps, overlapping or inclusion of intervals and instances is possible. Hence this framework allows an arbitrary layout of the time dimension. We implemented two ways to process space time datasets with arbitrary temporal layout, the temporal topology and the granularity based spatio-temporal algebra. The algebra provides the functionality to define complex spatio-temporal topological operators that process time and space in a single expression. The algebra includes methods to select map layers from space time datasets based on their temporal relations, to temporally shift time stamped map layers, to create temporal buffer and to snap time instances of time stamped map layers to create a valid temporal topology. In addition spatio-temporal operations can be evaluated within conditional statements. These

  14. Bi-stable optical element actuator device

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2002-01-01

    The present invention is a bistable optical element actuator device utilizing a powered means to move an actuation arm, to which an optical element is attached, between two stable positions. A non-powered means holds the actuation arm in either of the two stable positions. The optical element may be a electromagnetic (EM) radiation or particle source, an instrument, or EM radiation or particle transmissive reflective or absorptive elements. A bearing is used to transfer motion and smoothly transition the actuation arm between the two stable positions.

  15. GMRES and integral operators

    SciTech Connect

    Kelley, C.T.; Xue, Z.Q.

    1994-12-31

    Many discretizations of integral equations and compact fixed point problems are collectively compact and strongly convergent in spaces of continuous functions. These properties not only lead to stable and convergent approximations but also can be used in the construction of fast multilevel algorithms. Recently the GMRES algorithm has become a standard coarse mesh solver. The purpose of this paper is to show how the special properties of integral operators and their approximations are reflected in the performance of the GMRES iteration and how these properties can be used to strengthen the norm in which convergence takes place. The authors illustrate these ideas with composite Gauss rules for integral equations on the unit interval.

  16. Schwartz operators

    NASA Astrophysics Data System (ADS)

    Keyl, M.; Kiukas, J.; Werner, R. F.

    2016-05-01

    In this paper, we introduce Schwartz operators as a non-commutative analog of Schwartz functions and provide a detailed discussion of their properties. We equip them, in particular, with a number of different (but equivalent) families of seminorms which turns the space of Schwartz operators into a Fréchet space. The study of the topological dual leads to non-commutative tempered distributions which are discussed in detail as well. We show, in particular, that the latter can be identified with a certain class of quadratic forms, therefore making operations like products with bounded (and also some unbounded) operators and quantum harmonic analysis available to objects which are otherwise too singular for being a Hilbert space operator. Finally, we show how the new methods can be applied by studying operator moment problems and convergence properties of fluctuation operators.

  17. Improved Temporal Resolution of Ambient Seismic Noise Monitoring without the Green's Function

    NASA Astrophysics Data System (ADS)

    Hadziioannou, Céline; Larose, Eric; Baig, Adam; Campillo, Michel

    2010-05-01

    Ambient noise crosscorrelations have been used on several occasions to monitor temporal variations in seismic velocity. In particular, Brenguier et al. (Science, 2008) find coseismic and postseismic velocity changes around a fault zone in Parkfield, California. In this study, and in others, it was initially assumed that a correct reconstruction of the Green's function is as necessary for temporal monitoring as it is for imaging. We show through laboratory experiments that a stable waveform reconstruction is sufficient to retrieve relative temporal variations. Armed with this knowledge, we revisit the data from Parkfield. One way to obtain a stable waveform, with an acceptable signal to noise ratio, is to average the correlations over a long period of time. However, for the application to monitoring one wants the possibility of following short-term variations. How can we resolve this conflict and improve temporal resolution without sacrificing SNR? We show that by applying an adaptive filter (Baig et al, J. Geophys. Res., 2009) to the Parkfield dataset the temporal resolution can be increased from 30 days up to 1 day. With this, we show that the velocity drop observed is coseismic with the Parkfield earthquake.

  18. Stereoscopic video compression using temporal scalability

    NASA Astrophysics Data System (ADS)

    Puri, Atul; Kollarits, Richard V.; Haskell, Barry G.

    1995-04-01

    Despite the fact that human ability to perceive a high degree of realism is directly related to our ability to perceive depth accurately in a scene, most of the commonly used imaging and display technologies are able to provide only a 2D rendering of the 3D real world. Many current as well as emerging applications in areas of entertainment, remote operations, industrial and medicine can benefit from the depth perception offered by stereoscopic video systems which employ two views of a scene imaged under the constraints imposed by human visual system. Among the many challenges to be overcome for practical realization and widespread use of 3D/stereoscopic systems are efficient techniques for digital compression of enormous amounts of data while maintaining compatibility with normal video decoding and display systems. After a brief discussion on the relationship of digital stereoscopic 3DTV with digital TV and HDTV, we present an overview of tools in the MPEG-2 video standard that are relevant to our discussion on compression of stereoscopic video, which is the main topic of this paper. Next, we determine ways in which temporal scalability concepts can be applied to exploit redundancies inherent between the two views of a scene comprising stereoscopic video. Due consideration is given to masking properties of stereoscopic vision to determine bandwidth partitioning between the two views to realize an efficient coding scheme while providing sufficient quality. Simulations are performed on stereoscopic video of normal TV resolution to compare the performance of the two temporal scalability configurations with each other and with the simulcast solution. Preliminary results are quite promising and indicate that the configuration that exploits motion and disparity compensation significantly outperforms the one that exploits disparity compensation alone. Compression of both views of stereo video of normal TV resolution appears feasible in a total of 8 or 9 Mbit/s. Finally

  19. Temporal resolution enhancement from motion

    NASA Astrophysics Data System (ADS)

    Rollason, M. P.; Watson, G. H.; Strens, M. J. A.

    2009-09-01

    We describe progress in the third year of the EMRS DTC TEP theme project entitled "Temporal Resolution Enhancement from Motion". The aim is to develop algorithms that combine evidence over time from a sequence of images in order to improve spatial resolution and reduce unwanted artefacts. Years one and two of this project developed and demonstrated an efficient algorithm that provided good resolution enhancement of a scene viewed in the far field (approximately flat) [1]. This paper reports a new algorithm which is applicable to a three dimensional scene where substantial depth variation causes parallax within the imagery. The new algorithm is demonstrated using airborne infra-red imagery.

  20. Structured illumination temporal compressive microscopy

    PubMed Central

    Yuan, Xin; Pang, Shuo

    2016-01-01

    We present a compressive video microscope based on structured illumination with incoherent light source. The source-side illumination coding scheme allows the emission photons being collected by the full aperture of the microscope objective, and thus is suitable for the fluorescence readout mode. A 2-step iterative reconstruction algorithm, termed BWISE, has been developed to address the mismatch between the illumination pattern size and the detector pixel size. Image sequences with a temporal compression ratio of 4:1 were demonstrated. PMID:27231586

  1. Temporal pattern processing in songbirds.

    PubMed

    Comins, Jordan A; Gentner, Timothy Q

    2014-10-01

    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

  2. Modal and Temporal Argumentation Networks

    NASA Astrophysics Data System (ADS)

    Barringer, Howard; Gabbay, Dov M.

    The traditional Dung networks depict arguments as atomic and studies the relationships of attack between them. This can be generalised in two ways. One is to consider, for example, various forms of attack, support and feedback. Another is to add content to nodes and put there not just atomic arguments but more structure, for example, proofs in some logic or simply just formulas from a richer language. This paper offers to use temporal and modal language formulas to represent arguments in the nodes of a network. The suitable semantics for such networks is Kripke semantics. We also introduce a new key concept of usability of an argument.

  3. Temporal Variability of the Bioaerosol Background at a Subway Station: Concentration Level, Size Distribution, and Diversity of Airborne Bacteria

    PubMed Central

    Dybwad, Marius; Skogan, Gunnar

    2014-01-01

    Naturally occurring bioaerosol environments may present a challenge to biological detection-identification-monitoring (BIODIM) systems aiming at rapid and reliable warning of bioterrorism incidents. One way to improve the operational performance of BIODIM systems is to increase our understanding of relevant bioaerosol backgrounds. Subway stations are enclosed public environments which may be regarded as potential bioterrorism targets. This study provides novel information concerning the temporal variability of the concentration level, size distribution, and diversity of airborne bacteria in a Norwegian subway station. Three different air samplers were used during a 72-h sampling campaign in February 2011. The results suggested that the airborne bacterial environment was stable between days and seasons, while the intraday variability was found to be substantial, although often following a consistent diurnal pattern. The bacterial levels ranged from not detected to 103 CFU m−3 and generally showed increased levels during the daytime compared to the nighttime levels, as well as during rush hours compared to non-rush hours. The airborne bacterial levels showed rapid temporal variation (up to 270-fold) on some occasions, both consistent and inconsistent with the diurnal profile. Airborne bacterium-containing particles were distributed between different sizes for particles of >1.1 μm, although ∼50% were between 1.1 and 3.3 μm. Anthropogenic activities (mainly passengers) were demonstrated as major sources of airborne bacteria and predominantly contributed 1.1- to 3.3-μm bacterium-containing particles. Our findings contribute to the development of realistic testing and evaluation schemes for BIODIM equipment by providing information that may be used to simulate operational bioaerosol backgrounds during controlled aerosol chamber-based challenge tests with biological threat agents. PMID:24162566

  4. Effectiveness of Temporal Augmentation Using a Calvarial Onlay Graft during Pterional Craniotomy

    PubMed Central

    Kim, Yoon Soo; Yi, Hyung Suk; Kim, Han Kyu

    2016-01-01

    Temporal hollowing occurs to varying degrees after pterional craniotomy. The most common cause of temporal hollowing is a bony defect of the pterional and temporal regions due to the resection of the sphenoid ridge and temporal squama for adequate exposure without overhang. The augmentation of such bony defects is important in preventing craniofacial deformities and postoperative hollowness. Temporal cranioplasty has been performed using a range of materials, such as acrylics, porous polyethylene, bone cement, titanium, muscle flaps, and prosthetic dermis. These methods are limited by the risk of damage to adjacent tissue and infection, a prolonged preparation phase, the possibility of reabsorption, and cost inefficiency. We have developed a method of temporal augmentation using a calvarial onlay graft as a single-stage neurosurgical reconstructive operation in patients requiring craniotomy. In this report, we describe the surgical details and review our institutional outcomes. The patients were divided into pterional craniotomy and onlay graft groups. Clinical temporal hollowing was assessed using a visual analog scale (VAS). Temporal soft tissue thickness was measured on preoperative and postoperative computed tomography (CT) studies. Both the VAS and CT-based assessments were compared between the groups. Our review indicated that the use of an onlay graft was associated with a lower VAS score and left-right discrepancy in the temporal contour than were observed in patients undergoing pterional craniotomy without an onlay graft. PMID:27019813

  5. A System to Create Stable Nanoparticle Aerosols from Nanopowders.

    PubMed

    Ding, Yaobo; Riediker, Michael

    2016-01-01

    Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring minimal amounts of test materials (min. 200 mg), for studying powder aerosolization behavior and aerosol properties. The aerosolization procedure follows the concept of the fluidized-bed process, but occurs in the modified volume of a V-shaped aerosol generator. The airborne particle number concentration is adjustable by controlling the air flow rate. The system supplied stable aerosol generation rates and particle size distributions over long periods (0.5-2 hr and possibly longer), which are important, for example, to study aerosol behavior, but also for toxicological studies. Strict adherence to the operating procedures during the aerosolization experiments ensures the generation of reproducible test results. The critical steps in the standard protocol are the preparation of the material and setup, and the aerosolization operations themselves. The system can be used for experiments requiring stable aerosol concentrations and may also be an alternative method for testing dustiness. The controlled aerosolization made possible with this setup occurs using energy inputs (may be characterized by aerosolization air velocity) that are within the ranges commonly found in occupational environments where nanomaterial powders are handled. This setup and its operating protocol are thus helpful for human exposure and risk assessment. PMID:27501179

  6. Applications of stable isotopes in clinical pharmacology

    PubMed Central

    Schellekens, Reinout C A; Stellaard, Frans; Woerdenbag, Herman J; Frijlink, Henderik W; Kosterink, Jos G W

    2011-01-01

    This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the pharmacokinetic profile or mode of action of a drug substance. Secondly, stable isotopes may be used for the assessment of drug products or drug delivery systems by determination of parameters such as the bioavailability or the release profile. Thirdly, patients may be assessed in relation to patient-specific drug treatment; this concept is often called personalized medicine. In this article, the application of stable isotope technology in the aforementioned three areas is reviewed, with emphasis on developments over the past 25 years. The applications are illustrated with examples from clinical studies in humans. PMID:21801197

  7. Stable Isotope Signatures for Microbial Forensics

    SciTech Connect

    Kreuzer, Helen W.

    2012-01-03

    The isotopic distribution of the atoms composing the molecules of microorganisms is a function of the substrates used by the organisms. The stable isotope content of an organism is fixed so long as no further substrate consumption and biosynthesis occurs, while the radioactive isotopic content decays over time. The distribution of stable isotopes of C, N, O and H in heterotrophic microorganisms is a direct function of the culture medium, and therefore the stable isotope composition can be used to associate samples with potential culture media and also with one another. The 14C content depends upon the 14C content, and therefore the age, of the organic components of the culture medium, as well as on the age of the culture itself. Stable isotope signatures can thus be used for sample matching, to associate cultures with specific growth media, and to predict characteristics of growth media.

  8. DNA modifications: Another stable base in DNA

    NASA Astrophysics Data System (ADS)

    Brazauskas, Pijus; Kriaucionis, Skirmantas

    2014-12-01

    Oxidation of 5-methylcytosine has been proposed to mediate active and passive DNA demethylation. Tracking the history of DNA modifications has now provided the first solid evidence that 5-hydroxymethylcytosine is a stable epigenetic modification.

  9. Thermally Stable Piezoelectric and Pyroelectric Polymers

    NASA Technical Reports Server (NTRS)

    Simpson, Joycelyn O.; St. Clair, Terry L.

    2006-01-01

    A class of thermally stable piezoelectric and pyroelectric polymers, and an improved method of making them, have been invented. These polymers can be used as substrates for a wide variety of electromechanical transducers, sensors, and actuators.

  10. Computing Stable Outcomes in Hedonic Games

    NASA Astrophysics Data System (ADS)

    Gairing, Martin; Savani, Rahul

    We study the computational complexity of finding stable outcomes in symmetric additively-separable hedonic games. These coalition formation games are specified by an undirected edge-weighted graph: nodes are players, an outcome of the game is a partition of the nodes into coalitions, and the utility of a node is the sum of incident edge weights in the same coalition. We consider several natural stability requirements defined in the economics literature. For all of them the existence of a stable outcome is guaranteed by a potential function argument, so local improvements will converge to a stable outcome and all these problems are in PLS. The different stability requirements correspond to different local search neighbourhoods. For different neighbourhood structures, our findings comprise positive results in the form of polynomial-time algorithms for finding stable outcomes, and negative (PLS-completeness) results.

  11. Evolutionary origin of asymptotically stable consensus.

    PubMed

    Tang, Chang-Bing; Wu, Bin; Wang, Jian-Bo; Li, Xiang

    2014-01-01

    Consensus is widely observed in nature as well as in society. Up to now, many works have focused on what kind of (and how) isolated single structures lead to consensus, while the dynamics of consensus in interdependent populations remains unclear, although interactive structures are everywhere. For such consensus in interdependent populations, we refer that the fraction of population adopting a specified strategy is the same across different interactive structures. A two-strategy game as a conflict is adopted to explore how natural selection affects the consensus in such interdependent populations. It is shown that when selection is absent, all the consensus states are stable, but none are evolutionarily stable. In other words, the final consensus state can go back and forth from one to another. When selection is present, there is only a small number of stable consensus state which are evolutionarily stable. Our study highlights the importance of evolution on stabilizing consensus in interdependent populations. PMID:24699444

  12. Polymeric foams stable at high temperatures

    NASA Technical Reports Server (NTRS)

    Riccitiello, S. R.; Harrison, E. S.; Delano, C. B.

    1976-01-01

    Crosslinked poly(N-arylenebenzimidazoles) are stable up to 370 C. Polymers are made by mixing appropriate stoichiometric amounts of tetramine and aromatic dicarboxylic acid anhydride with phenol or alkyl-substituted phenol.

  13. Stable vector bundles and string theory

    SciTech Connect

    Gomez, Tomas L.; Sols, Ignacio; Lukic, Sergio

    2009-05-06

    In [4], Braun, He, Ovrut and Pantev proposed a model of string theory (based on the Calabi-Yau 3-fold X) whose low energy limit predicts certain properties of the Standard Model of particle Physics. This model depends on two vector bundles that have to be stable. We calculate the ample cone of X, and prove that one of them is stable, and the other one is not.

  14. Analysis of temporal jitter in a copper vapor laser system.

    PubMed

    Durga Praveen Kumar, D; Gantayet, L M; Singh, Sunita; Rawat, A S; Rana, Paramjit; Rajasree, V; Agarwalla, Sandeep K; Chakravarthy, D P

    2012-02-01

    Temporal jitter in a magnetic pulse compression based copper vapor laser (CVL) system is analyzed by considering ripple present in the input dc power supply and ripple present in the magnetic core resetting power supply. It is shown that the jitter is a function of the ratio of operating voltage to the designed voltage, percentage ripple, and the total propagation delay of the magnetic pulse compression circuit. Experimental results from a CVL system operating at a repetition rate of 9 kHz are presented. PMID:22380123

  15. A Stable and Conservative Interface Treatment of Arbitrary Spatial Accuracy

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Nordstrom, Jan; Gottlieb, David

    1998-01-01

    Stable and accurate interface conditions are derived for the linear advection-diffusion equation. The conditions are functionally independent of the spatial order of accuracy and rely only on the form of the discrete operator. We focus on high-order finite-difference operators that satisfy the summation-by-parts (SBP) property. We prove that stability is a natural consequence of the SBP operators used in conjunction with the new boundary conditions. In addition, we show that the interface treatments are conservative. New finite-difference operators of spatial accuracy up to sixth order are constructed: these operators satisfy the SBP property. Finite-difference operators are shown to admit design accuracy (p(sup th)-order global accuracy) when (p - 1)(sup th)-order stencil closures are used near the boundaries if the physical boundary conditions are implemented to at least p(sup th)-order accuracy. Stability and accuracy are demonstrated on the nonlinear Burgers' equation for an twelve-subdomain problem with randomly distributed interfaces.

  16. Temporal asynchrony and spatial perception

    PubMed Central

    Lev, Maria; Polat, Uri

    2016-01-01

    Collinear facilitation is an enhancement in the visibility of a target by laterally placed iso-oriented flankers in a collinear (COL) configuration. Iso-oriented flankers placed in a non-collinear configuration (side-by-side, SBS) produce less facilitation. Surprisingly, presentation of both configurations simultaneously (ISO-CROSS) abolishes the facilitation rather than increases it - a phenomenon that can’t be fully explained by the spatial properties of the target and flankers. Based on our preliminary data and recent studies, we hypothesized that there might be a novel explanation based on the temporal properties of the excitation and inhibition, resulting in asynchrony between the lateral inputs received from COL and SBS, leading to cancelation of the facilitatory component in ISO-CROSS. We explored this effect using a detection task in humans. The results replicated the previous results showing that the preferred facilitation for COL and SBS was abolished for the ISO-CROSS configuration. However, presenting the SBS flankers, but not the COL flankers 20 msec before ISO-CROSS restored the facilitatory effect. We propose a novel explanation that the perceptual advantage of collinear facilitation may be cancelled by the delayed input from the sides; thus, the final perception is determined by the overall spatial-temporal integration of the lateral interactions. PMID:27460532

  17. Management of temporal bone trauma.

    PubMed

    Patel, Alpen; Groppo, Eli

    2010-06-01

    The temporal bones are paired structures located on the lateral aspects of the skull and contribute to the skull base. Trauma is usually the result of blunt head injury and can result in damage to the brain and meninges, the middle and internal ear, and the facial nerve. Complications can include intracranial hemorrhage, cerebral contusion, CSF leak and meningitis, hearing loss, vertigo, and facial paralysis. To prevent these complications, diagnosis followed by appropriate medical and surgical management is critical. Diagnosis relies primarily on physical signs and symptoms as well as radiographic imaging. Emergent intervention is required in situations involving herniation of the brain into the middle ear cavity or hemorrhage of the intratemporal carotid artery. Patients with declining facial nerve function are candidates for early surgical intervention. Conductive hearing loss can be corrected surgically as an elective procedure, while sensorineural hearing loss carries a poor prognosis, regardless of management approach. Children generally recover from temporal bone trauma with fewer complications than adults and experience a markedly lower incidence of facial nerve paralysis. PMID:22110824

  18. Temporal structure in associative retrieval

    PubMed Central

    Kurth-Nelson, Zeb; Barnes, Gareth; Sejdinovic, Dino; Dolan, Ray; Dayan, Peter

    2015-01-01

    Electrophysiological data disclose rich dynamics in patterns of neural activity evoked by sensory objects. Retrieving objects from memory reinstates components of this activity. In humans, the temporal structure of this retrieved activity remains largely unexplored, and here we address this gap using the spatiotemporal precision of magnetoencephalography (MEG). In a sensory preconditioning paradigm, 'indirect' objects were paired with 'direct' objects to form associative links, and the latter were then paired with rewards. Using multivariate analysis methods we examined the short-time evolution of neural representations of indirect objects retrieved during reward-learning about direct objects. We found two components of the evoked representation of the indirect stimulus, 200 ms apart. The strength of retrieval of one, but not the other, representational component correlated with generalization of reward learning from direct to indirect stimuli. We suggest the temporal structure within retrieved neural representations may be key to their function. DOI: http://dx.doi.org/10.7554/eLife.04919.001 PMID:25615722

  19. Temporal Constraint Reasoning With Preferences

    NASA Technical Reports Server (NTRS)

    Khatib, Lina; Morris, Paul; Morris, Robert; Rossi, Francesca

    2001-01-01

    A number of reasoning problems involving the manipulation of temporal information can naturally be viewed as implicitly inducing an ordering of potential local decisions involving time (specifically, associated with durations or orderings of events) on the basis of preferences. For example. a pair of events might be constrained to occur in a certain order, and, in addition. it might be preferable that the delay between them be as large, or as small, as possible. This paper explores problems in which a set of temporal constraints is specified, where each constraint is associated with preference criteria for making local decisions about the events involved in the constraint, and a reasoner must infer a complete solution to the problem such that, to the extent possible, these local preferences are met in the best way. A constraint framework for reasoning about time is generalized to allow for preferences over event distances and durations, and we study the complexity of solving problems in the resulting formalism. It is shown that while in general such problems are NP-hard, some restrictions on the shape of the preference functions, and on the structure of the preference set, can be enforced to achieve tractability. In these cases, a simple generalization of a single-source shortest path algorithm can be used to compute a globally preferred solution in polynomial time.

  20. Awareness of Temporal Lag is Necessary for Motor–Visual Temporal Recalibration

    PubMed Central

    Tsujita, Masaki; Ichikawa, Makoto

    2016-01-01

    Consistent exposure to a temporal lag between observers' voluntary action and its visual feedback induced recalibration of temporal order perception between a motor action and a visual stimulus. It remains unclear what kinds of processing underlie this motor–visual temporal recalibration. This study examined the necessity of awareness of a temporal lag between a motor action and its visual feedback for motor–visual temporal recalibration. In Experiment 1, we allocated observers to either the multiple-step or single-step lag conditions. In the multiple-step lag condition, we first inserted a small temporal lag and subsequently increased it with progress of the adaptation period, to make observers unaware of the temporal lag during the adaptation period. In the single-step lag condition, we instructed observers about the temporal lag before adaptation, and inserted a substantial temporal lag from the beginning of the adaptation period to ensure that they were aware of the temporal lag. We found significant recalibration only in the single-step lag condition. In Experiment 2, we exposed all observers to a substantial temporal lag from the beginning of adaptation period with no instruction about insertion of the temporal lag. We asked observers at the end of the experiment whether they were aware of the temporal lag. We found significant recalibration for only observers who were aware of the lag. These results suggest that awareness of the temporal lag plays a crucial role in motor–visual temporal recalibration. PMID:26778983

  1. Tracing Cadmium in the Environment: an Evolving Stable Isotope Approach

    NASA Astrophysics Data System (ADS)

    Bullen, T. D.; Bouse, R. M.; Brown, C. L.; Croteau, M.; Luoma, S. N.; Topping, B. R.

    2005-05-01

    Cadmium (Cd) is a trace constituent in rocks and waters, and like many transition metals is an essential dietary nutrient at low levels but highly toxic in elevated doses. In many respects, cadmium behaves chemically like calcium (Ca) and thus substitutes for Ca in liquid-solid partitioning reactions and generally follows Ca through biogeochemical cycles and metabolic processes. Cd is comprised of 8 stable isotopes, and given the isotopic systematics of environmental Ca it is likely that variations in the stable isotope composition of Cd in natural materials will result from both inorganic and biologic processes. In order to assess the potential of Cd isotope variations to reveal information about sources, metabolic and biogeochemical pathways and fates of environmental Cd, we have initiated a broad study of the stable isotope composition of Cd in a variety of natural and anthropogenically-influenced systems. As an example, here we report the results of the first systematic study of the stable isotope composition of Cd in biologic materials. We focused on the isotopic variability of Cd in tissues of two species of clam collected from the San Francisco Bay estuary, Potamocorbula amurensis which resides in brackish water and Corbicula fluminea which resides in fresh and slightly brackish water. Both clam species concentrate Cd in their soft and hard tissues. During both low-flow conditions in August and high-flow conditions in April, δ116Cd of soft tissues of Potamocorbula was consistently negative and increased down-estuary with increasing salinity (δ116Cd is defined as the per mil difference of the 116Cd/110Cd ratio between a sample and our standard, igneous rock BIR-1). Samples collected in August were systematically displaced to higher δ116Cd than those collected in April. Soft tissues of Corbicula collected in both August and April from upstream, fully fresh-water sampling sites had identical δ116Cd, while soft tissues of Corbicula collected from our site at

  2. Apparatus to detect stable fractional charges on matter

    SciTech Connect

    Vanderspek, R.

    1980-04-01

    The construction of an apparatus designed to detect stable fractional charges on matter, if they exist, to the level of 10/sup -24/ per nucleon is reported and discussed. The charges on a stream of highly consistent droplets produced by the apparatus are determined by accurate measurement of the deflection of the droplets in falling through a static electric field. Maintenance of certain parameters of operation calculated to limit the random effects of electrical and aerodynamical disturbances on the droplets indicate a precision in the measurement of the charge on a droplet of 0.02e can be attained. 7 figures.

  3. Approach to inherently stable interfaces for ceramic matrix composites

    SciTech Connect

    Besmann, T.M.; Kupp, E.R.; Stinton, D.P.; Shanmugham, S.

    1996-09-01

    Virtually all ceramic matrix composites require and interface coating between the fibers and matrix to achieve the desired mechanical performance. To date, the most effective interface materials for non- oxide matrix composites have been carbon and boron nitride. They are, however, susceptible to oxidation at elevated temperatures, and thus under many envisioned operating environments they will fail, possibly allowing oxidation of the fibers as well, adversely affecting mechanical behavior. Current efforts are directed toward developing stable interface coating, which include oxides and silicon carbide with appropriate thermomechanical properties.

  4. Tracing amino acid exchange during host-pathogen interaction by combined stable-isotope time-resolved Raman spectral imaging

    NASA Astrophysics Data System (ADS)

    Naemat, Abida; Elsheikha, Hany M.; Boitor, Radu A.; Notingher, Ioan

    2016-02-01

    This study investigates the temporal and spatial interchange of the aromatic amino acid phenylalanine (Phe) between human retinal pigment epithelial cell line (ARPE-19) and tachyzoites of the apicomplexan protozoan parasite Toxoplasma gondii (T. gondii). Stable isotope labelling by amino acids in cell culture (SILAC) is combined with Raman micro-spectroscopy to selectively monitor the incorporation of deuterium-labelled Phe into proteins in individual live tachyzoites. Our results show a very rapid uptake of L-Phe(D8) by the intracellular growing parasite. T. gondii tachyzoites are capable of extracting L-Phe(D8) from host cells as soon as it invades the cell. L-Phe(D8) from the host cell completely replaces the L-Phe within T. gondii tachyzoites 7-9 hours after infection. A quantitative model based on Raman spectra allowed an estimation of the exchange rate of Phe as 0.5-1.6 × 104 molecules/s. On the other hand, extracellular tachyzoites were not able to consume L-Phe(D8) after 24 hours of infection. These findings further our understanding of the amino acid trafficking between host cells and this strictly intracellular parasite. In particular, this study highlights new aspects of the metabolism of amino acid Phe operative during the interaction between T. gondii and its host cell.

  5. Tracing amino acid exchange during host-pathogen interaction by combined stable-isotope time-resolved Raman spectral imaging

    PubMed Central

    Naemat, Abida; Elsheikha, Hany M.; Boitor, Radu A.; Notingher, Ioan

    2016-01-01

    This study investigates the temporal and spatial interchange of the aromatic amino acid phenylalanine (Phe) between human retinal pigment epithelial cell line (ARPE-19) and tachyzoites of the apicomplexan protozoan parasite Toxoplasma gondii (T. gondii). Stable isotope labelling by amino acids in cell culture (SILAC) is combined with Raman micro-spectroscopy to selectively monitor the incorporation of deuterium-labelled Phe into proteins in individual live tachyzoites. Our results show a very rapid uptake of l-Phe(D8) by the intracellular growing parasite. T. gondii tachyzoites are capable of extracting l-Phe(D8) from host cells as soon as it invades the cell. l-Phe(D8) from the host cell completely replaces the l-Phe within T. gondii tachyzoites 7–9 hours after infection. A quantitative model based on Raman spectra allowed an estimation of the exchange rate of Phe as 0.5–1.6 × 104 molecules/s. On the other hand, extracellular tachyzoites were not able to consume l-Phe(D8) after 24 hours of infection. These findings further our understanding of the amino acid trafficking between host cells and this strictly intracellular parasite. In particular, this study highlights new aspects of the metabolism of amino acid Phe operative during the interaction between T. gondii and its host cell. PMID:26857158

  6. NICMOS FOM Operation Test

    NASA Astrophysics Data System (ADS)

    Noll, Keith

    2001-07-01

    This test verifies the FOM's mechanical operation. A 7 x 1 grid of points will be made by moving the FOM in steps of 6.5 from -20 to +19 arcsec relative to the 0 position {-36 to +3 relative to the default NIC3 FOM position of +16 arcsec}. We also have an additional FOM position at the default NIC3 position. These exposures all use the F166N filter. At the end of this sequence we will take F222M exposures at three additional FOM positions, the default position {+16 arcsec relative to the center point of the FOM mechanical range} and +/- 2 arcsec. This is to test for vignetting. Prerequisites for this test are cool down to nominal operating temperature {cold and stable, near the expected final temperature set point, but not necessarily the final temperature set point} and the filter wheel minifunctional and the filter wheel tests {proposals 8944 and 8972}.

  7. Treating autism by targeting the temporal lobes.

    PubMed

    Chi, Richard P; Snyder, Allan W

    2014-11-01

    Compelling new findings suggest that an early core signature of autism is a deficient left anterior temporal lobe response to language and an atypical over-activation of the right anterior temporal lobe. Intriguingly, our recent results from an entirely different line of reasoning and experiments also show that applying cathodal stimulation (suppressing) at the left anterior temporal lobe together with anodal stimulation (facilitating) at the right anterior temporal lobe, by transcranial direct current stimulation (tDCS), can induce some autistic-like cognitive abilities in otherwise normal adults. If we could briefly induce autistic like cognitive abilities in healthy individuals, it follows that we might be able to mitigate some autistic traits by reversing the above stimulation protocol, in an attempt to restore the typical dominance of the left anterior temporal lobe. Accordingly, we hypothesize that at least some autistic traits can be mitigated, by applying anodal stimulation (facilitating) at the left anterior temporal lobe together with cathodal stimulation (suppressing) at the right anterior temporal lobe. Our hypothesis is supported by strong convergent evidence that autistic symptoms can emerge and later reverse due to the onset and subsequent recovery of various temporal lobe (predominantly the left) pathologies. It is also consistent with evidence that the temporal lobes (especially the left) are a conceptual hub, critical for extracting meaning from lower level sensory information to form a coherent representation, and that a deficit in the temporal lobes underlies autistic traits. PMID:25227333

  8. Spectro-Temporal Weighting of Loudness

    PubMed Central

    Oberfeld, Daniel; Heeren, Wiebke; Rennies, Jan; Verhey, Jesko

    2012-01-01

    Real-world sounds like speech or traffic noise typically exhibit spectro-temporal variability because the energy in different spectral regions evolves differently as a sound unfolds in time. However, it is currently not well understood how the energy in different spectral and temporal portions contributes to loudness. This study investigated how listeners weight different temporal and spectral components of a sound when judging its overall loudness. Spectral weights were measured for the combination of three loudness-matched narrowband noises with different center frequencies. To measure temporal weights, 1,020-ms stimuli were presented, which randomly changed in level every 100 ms. Temporal weights were measured for each narrowband noise separately, and for a broadband noise containing the combination of the three noise bands. Finally, spectro-temporal weights were measured with stimuli where the level of the three narrowband noises randomly and independently changed every 100 ms. The data consistently showed that (i) the first 300 ms of the sounds had a greater influence on overall loudness perception than later temporal portions (primacy effect), and (ii) the lowest noise band contributed significantly more to overall loudness than the higher bands. The temporal weights did not differ between the three frequency bands. Notably, the spectral weights and temporal weights estimated from the conditions with only spectral or only temporal variability were very similar to the corresponding weights estimated in the spectro-temporal condition. The results indicate that the temporal and the spectral weighting of the loudness of a time-varying sound are independent processes. The spectral weights remain constant across time, and the temporal weights do not change across frequency. The results are discussed in the context of current loudness models. PMID:23209670

  9. Spatio-temporal variation in European starling reproductive success at multiple small spatial scales

    PubMed Central

    Brickhill, Daisy; Evans, Peter GH; Reid, Jane M

    2015-01-01

    Understanding population dynamics requires spatio-temporal variation in demography to be measured across appropriate spatial and temporal scales. However, the most appropriate spatial scale(s) may not be obvious, few datasets cover sufficient time periods, and key demographic rates are often incompletely measured. Consequently, it is often assumed that demography will be spatially homogeneous within populations that lack obvious subdivision. Here, we quantify small-scale spatial and temporal variation in a key demographic rate, reproductive success (RS), within an apparently contiguous population of European starlings. We used hierarchical cluster analysis to define spatial clusters of nest sites at multiple small spatial scales and long-term data to test the hypothesis that small-scale spatio-temporal variation in RS occurred. RS was measured as the number of chicks alive ca. 12 days posthatch either per first brood or per nest site per breeding season (thereby incorporating multiple breeding attempts). First brood RS varied substantially among spatial clusters and years. Furthermore, the pattern of spatial variation was stable across years; some nest clusters consistently produced more chicks than others. Total seasonal RS also varied substantially among spatial clusters and years. However, the magnitude of variation was much larger and the pattern of spatial variation was no longer temporally consistent. Furthermore, the estimated magnitude of spatial variation in RS was greater at smaller spatial scales. We thereby demonstrate substantial spatial, temporal, and spatio-temporal variation in RS occurring at very small spatial scales. We show that the estimated magnitude of this variation depended on spatial scale and that spatio-temporal variation would not have been detected if season-long RS had not been measured. Such small-scale spatio-temporal variation should be incorporated into empirical and theoretical treatments of population dynamics. PMID:26380670

  10. Efficacy of petrosectomy in malignant invasion of the temporal bone.

    PubMed

    Wierzbicka, M; Kopeć, T; Szyfter, W; Buczkowska, A; Borucki, Ł

    2016-09-01

    We present the outcomes of lateral, subtotal, and total petrosectomies in patients with invasion of the temporal bone by specific primary cancers, with particular emphasis on survival in the advanced stages of disease. We made a retrospective study of 20 consecutive patients (squamous cell carcinoma of the temporal bone, n=11, and primary cancer of the parotid gland with infiltration of the lateral skull base, n=9) treated by total, subtotal, or lateral petrosectomy at the University Department of Otolaryngology, a tertiary referral centre, between June 2006 and December 2010. Fourteen of the 20 patients were alive at the time of analysis, and follow-up ranged from 36-60 months. Six of seven patients whose disease relapsed (4 local and 3 distant metastases) died. The three-year, disease-free survival was 65% and the overall survival 68%. Survival between those with temporal bone and parotid tumours did not differ significantly. The combined group survival was affected by involvement of invaded resection margins (n=6, p=0.03). Involved margins were significant in the development of recurrence (p=0.03). Tumour stage, nodal involvement, type of operation, sex, age, skin involvement, facial palsy, and previous history of disease had no impact on prognosis. There was a significant difference in the survival curves of patients with carcinoma of the temporal bone with and without facial paresis (n=6 compared with n=5; p=0.046). Two of 11 free flaps required revision of the anastomoses, but none was lost. PMID:27241556

  11. Spatio-Temporal Multiscale Denoising of Fluoroscopic Sequence.

    PubMed

    Amiot, Carole; Girard, Catherine; Chanussot, Jocelyn; Pescatore, Jeremie; Desvignes, Michel

    2016-06-01

    In the past 20 years, a wide range of complex fluoroscopically guided procedures have shown considerable growth. Biologic effects of the exposure (radiation induced burn, cancer) lead to reduce the dose during the intervention, for the safety of patients and medical staff. However, when the dose is reduced, image quality decreases, with a high level of noise and a very low contrast. Efficient restoration and denoising algorithms should overcome this drawback. We propose a spatio-temporal filter operating in a multi-scales space. This filter relies on a first order, motion compensated, recursive temporal denoising. Temporal high frequency content is first detected and then matched over time to allow for a strong denoising in the temporal axis. We study this filter in the curvelet domain and in the dual-tree complex wavelet domain, and compare those results to state of the art methods. Quantitative and qualitative analysis on both synthetic and real fluoroscopic sequences demonstrate that the proposed filter allows a great dose reduction. PMID:26812705

  12. CNTRO 2.0: A Harmonized Semantic Web Ontology for Temporal Relation Inferencing in Clinical Narratives

    PubMed Central

    Tao, Cui; Solbrig, Harold R.; Chute, Christopher G.

    2011-01-01

    The Clinical Narrative Temporal Relation Ontology (CNTRO) has been developed for the purpose of allowing temporal information of clinical data to be semantically annotated and queried, and using inference to expose new temporal features and relations based on the semantic assertions and definitions of the temporal aspects in the ontology. While CNTRO provides a formal semantic foundation to leverage the semantic-web techniques, it is still necessary to arrive at a shared set of semantics and operational rules with commonly used ontologies for the time domain. This paper introduces CNTRO 2.0, which tries to harmonize CNTRO 1.0 and a list of existing time ontologies or top-level ontologies into a unified model—an OWL based ontology of temporal relations for clinical research. PMID:22211182

  13. CNTRO 2.0: A Harmonized Semantic Web Ontology for Temporal Relation Inferencing in Clinical Narratives.

    PubMed

    Tao, Cui; Solbrig, Harold R; Chute, Christopher G

    2011-01-01

    The Clinical Narrative Temporal Relation Ontology (CNTRO) has been developed for the purpose of allowing temporal information of clinical data to be semantically annotated and queried, and using inference to expose new temporal features and relations based on the semantic assertions and definitions of the temporal aspects in the ontology. While CNTRO provides a formal semantic foundation to leverage the semantic-web techniques, it is still necessary to arrive at a shared set of semantics and operational rules with commonly used ontologies for the time domain. This paper introduces CNTRO 2.0, which tries to harmonize CNTRO 1.0 and a list of existing time ontologies or top-level ontologies into a unified model-an OWL based ontology of temporal relations for clinical research. PMID:22211182

  14. Warehousing Operations.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on warehousing operations is designed to provide instruction in the procedures used in warehousing operations. Introductory materials include specific information for MCI students and a study guide (guidelines to complete the course). The 22-hour…

  15. Operational Amplifiers.

    ERIC Educational Resources Information Center

    Foxcroft, G. E.

    1986-01-01

    Addresses the introduction of low cost equipment into high school and college physical science classes. Examines the properties of an "ideal" operational amplifier and discusses how it might be used under saturated and non-saturated conditions. Notes the action of a "real" operational amplifier. (TW)

  16. Operational efficiency

    NASA Technical Reports Server (NTRS)

    Bland, Dan; Davis, Tom; Griffin, Sandy

    1990-01-01

    Space transportation avionics technology operational efficiency issues are presented in viewgraph form. Information is given on ascent flight design, autonomous spacecraft control, operations management systems, advanced mission control, telerobotics/telepresence, advanced software integration, advanced test/checkout systems, advanced training systems, and systems monitoring.

  17. Business & Operations

    ERIC Educational Resources Information Center

    Agron, Joe

    2007-01-01

    This article presents an interview with John D. Musso, executive director of the Association of School Business Officials (ASBO) International. Musso talks about trends and issues that will most affect school business and operations in 2007 and beyond. Despite the challenges facing school operations, he believes that the key to being successful at…

  18. Temporal sensitivity. [time dependent human perception of visual stimuli

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.

    1986-01-01

    Human visual temporal sensitivity is examined. The stimuli used to measure temporal sensitivity are described and the linear systems theory is reviewed in terms of temporal sensitivity. A working model which represents temporal sensitivity is proposed. The visibility of a number of temporal wave forms, sinusoids, rectangular pulses, and pulse pairs, is analyzed. The relation between spatial and temporal effects is studied. Temporal variations induced by image motion and the effects of light adaptation on temporal sensitivity are considered.

  19. Development of a subway operation incident delay model using accelerated failure time approaches.

    PubMed

    Weng, Jinxian; Zheng, Yang; Yan, Xuedong; Meng, Qiang

    2014-12-01

    This study aims to develop a subway operational incident delay model using the parametric accelerated time failure (AFT) approach. Six parametric AFT models including the log-logistic, lognormal and Weibull models, with fixed and random parameters are built based on the Hong Kong subway operation incident data from 2005 to 2012, respectively. In addition, the Weibull model with gamma heterogeneity is also considered to compare the model performance. The goodness-of-fit test results show that the log-logistic AFT model with random parameters is most suitable for estimating the subway incident delay. First, the results show that a longer subway operation incident delay is highly correlated with the following factors: power cable failure, signal cable failure, turnout communication disruption and crashes involving a casualty. Vehicle failure makes the least impact on the increment of subway operation incident delay. According to these results, several possible measures, such as the use of short-distance and wireless communication technology (e.g., Wifi and Zigbee) are suggested to shorten the delay caused by subway operation incidents. Finally, the temporal transferability test results show that the developed log-logistic AFT model with random parameters is stable over time. PMID:25171521

  20. Multiobjective optimization of temporal processes.

    PubMed

    Song, Zhe; Kusiak, Andrew

    2010-06-01

    This paper presents a dynamic predictive-optimization framework of a nonlinear temporal process. Data-mining (DM) and evolutionary strategy algorithms are integrated in the framework for solving the optimization model. DM algorithms learn dynamic equations from the process data. An evolutionary strategy algorithm is then applied to solve the optimization problem guided by the knowledge extracted by the DM algorithm. The concept presented in this paper is illustrated with the data from a power plant, where the goal is to maximize the boiler efficiency and minimize the limestone consumption. This multiobjective optimization problem can be either transformed into a single-objective optimization problem through preference aggregation approaches or into a Pareto-optimal optimization problem. The computational results have shown the effectiveness of the proposed optimization framework. PMID:19900853

  1. Hourly temporal distribution of wind

    NASA Astrophysics Data System (ADS)

    Deligiannis, Ilias; Dimitriadis, Panayiotis; Koutsoyiannis, Demetris

    2016-04-01

    The wind process is essential for hydrometeorology and additionally, is one of the basic renewable energy resources. Most stochastic forecast models are limited up to daily scales disregarding the hourly scale which is significant for renewable energy management. Here, we analyze hourly wind timeseries giving emphasis on the temporal distribution of wind within the day. We finally present a periodic model based on statistical as well as hydrometeorological reasoning that shows good agreement with data. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  2. Temporal resolution enhancement from motion

    NASA Astrophysics Data System (ADS)

    Rollason, M. P.; Strens, M. J. A.; Gardner, A. P.

    2008-10-01

    We describe progress in the second year of the EMRS DTC TEP theme project entitled "Temporal Resolution Enhancement from Motion". The aim is to develop algorithms that combine evidence over time from a sequence of images in order to improve spatial resolution and reduce unwanted artefacts. A C++ implementation of an algorithm was developed in year one 1. Work in year two has improved the efficiency and extended the applicability of the algorithm. New schemes for information update and scene matching have substantially reduced the processing time and enabled application of the technique to imagery with more complicated viewing geometries. The new technique is demonstrated using airborne infra-red imagery datasets from a Wescam MX series turret on a helicopter.

  3. Seismic interferometry for temporal monitoring

    NASA Astrophysics Data System (ADS)

    Nakata, Norimitsu

    Seismic interferometry, where one computes coherency of waves between two or more receivers and averages over many sources, is a technique of signal processing to reconstruct wavefields. This technique is used in geophysics, especially exploration geophysics and seismology. After more than a half century from the first study related to seismic interferometry (although the name of seismic interferometry has been used for approximately the last 15 years), researchers have developed this technique for many aspects: using multiples for increasing illuminations, enhancement of survey areas, ambient-noise analysis, and removal of the imprint of a complicated overburden. In this dissertation, I focus on the advantages of seismic interferometry for time-lapse measurements. Measurements of temporal changes yield beneficial information of fluid flow, crustal deformation, temperature, and/or stress. Estimation of temporal changes using active sources is, however, technically and economically challenging. Because seismic interferometry reconstruct waves that would have been recorded with a repeatable active sources using only receivers, this technique is appropriate for temporal monitoring. With seismic interferometry, one obtains some advantages that include canceling the complexity of wave propagation to a virtual source, creating virtual shear-wave (S-wave) sources (active S sources are expensive), and using waves that are not usable for active sources (e.g., ambient noise and multiples). I seek applications of seismic interferometry in a variety of topics (i.e., seismology, structural engineering, and exploration geophysics), and develop and/or modify several techniques of seismic interferometry for each application. Some chapters focus on developing techniques of seismic interferometry, and other chapters aim to estimate and interpret temporal changes with the developed techniques. For passive seismic sources, deconvolution-based seismic interferometry has better

  4. Motor Activity Improves Temporal Expectancy

    PubMed Central

    Fautrelle, Lilian; Mareschal, Denis; French, Robert; Addyman, Caspar; Thomas, Elizabeth

    2015-01-01

    Certain brain areas involved in interval timing are also important in motor activity. This raises the possibility that motor activity might influence interval timing. To test this hypothesis, we assessed interval timing in healthy adults following different types of training. The pre- and post-training tasks consisted of a button press in response to the presentation of a rhythmic visual stimulus. Alterations in temporal expectancy were evaluated by measuring response times. Training consisted of responding to the visual presentation of regularly appearing stimuli by either: (1) pointing with a whole-body movement, (2) pointing only with the arm, (3) imagining pointing with a whole-body movement, (4) simply watching the stimulus presentation, (5) pointing with a whole-body movement in response to a target that appeared at irregular intervals (6) reading a newspaper. Participants performing a motor activity in response to the regular target showed significant improvements in judgment times compared to individuals with no associated motor activity. Individuals who only imagined pointing with a whole-body movement also showed significant improvements. No improvements were observed in the group that trained with a motor response to an irregular stimulus, hence eliminating the explanation that the improved temporal expectations of the other motor training groups was purely due to an improved motor capacity to press the response button. All groups performed a secondary task equally well, hence indicating that our results could not simply be attributed to differences in attention between the groups. Our results show that motor activity, even when it does not play a causal or corrective role, can lead to improved interval timing judgments. PMID:25806813

  5. Restoring Natural Streamflow Variability by Modifying Multi-purpose Reservoir Operation

    NASA Astrophysics Data System (ADS)

    Shiau, J.

    2010-12-01

    Multi-purpose reservoirs typically provide benefits of water supply, hydroelectric power, and flood mitigation. Hydroelectric power generations generally do not consume water. However, temporal distribution of downstream flows is highly changed due to hydro-peaking effects. Associated with offstream diversion of water supplies for municipal, industrial, and agricultural requirements, natural streamflow characteristics of magnitude, duration, frequency, timing, and rate of change is significantly altered by multi-purpose reservoir operation. Natural flow regime has long been recognized a master factor for ecosystem health and biodiversity. Restoration of altered flow regime caused by multi-purpose reservoir operation is the main objective of this study. This study presents an optimization framework that modifying reservoir operation to seeking balance between human and environmental needs. The methodology presented in this study is applied to the Feitsui Reservoir, located in northern Taiwan, with main purpose of providing stable water-supply and auxiliary purpose of electricity generation and flood-peak attenuation. Reservoir releases are dominated by two decision variables, i.e., duration of water releases for each day and percentage of daily required releases within the duration. The current releasing policy of the Feitsui Reservoir releases water for water-supply and hydropower purposes during 8:00 am to 16:00 pm each day and no environmental flows releases. Although greater power generation is obtained by 100% releases distributed within 8-hour period, severe temporal alteration of streamflow is observed downstream of the reservoir. Modifying reservoir operation by relaxing these two variables and reserve certain ratio of streamflow as environmental flow to maintain downstream natural variability. The optimal reservoir releasing policy is searched by the multi-criterion decision making technique for considering reservoir performance in terms of shortage ratio

  6. Improving the algorithm of temporal relation propagation

    NASA Astrophysics Data System (ADS)

    Shen, Jifeng; Xu, Dan; Liu, Tongming

    2005-03-01

    In the military Multi Agent System, every agent needs to analyze the temporal relationships among the tasks or combat behaviors, and it"s very important to reflect the battlefield situation in time. The temporal relation among agents is usually very complex, and we model it with interval algebra (IA) network. Therefore an efficient temporal reasoning algorithm is vital in battle MAS model. The core of temporal reasoning is path consistency algorithm, an efficient path consistency algorithm is necessary. In this paper we used the Interval Matrix Calculus (IMC) method to represent the temporal relation, and optimized the path consistency algorithm by improving the efficiency of propagation of temporal relation based on the Allen's path consistency algorithm.

  7. The accumulation of stable cytogenetic rearrangements with age-determined by chromosome painting

    SciTech Connect

    Ramsey, M.J.; Lee, D.A.; Senft, J.R.; Briner, J.F.; Moore, D.H. II; Tucker, J.D.

    1994-12-31

    Chromosome painting is a rapid method of quantifying structural chromosomal rearrangements. The method is particularly useful for detecting stable aberrations which are difficult and expensive to quantify with classical methods. Translocations, being inherently stable, can be used as a biodosimeter for chronic and temporally-displaced exposure to radiation. Translocations may also be useful for quantifying chronic exposure to environmentally related agents which may result in an accumulation of cytogenetic damage with age. Because most chemical exposures are low and chronic, conventional cytogenetic methods are not expected to be informative. To understand the extent that age and lifestyle factors impact the frequency of stable aberrations, we used chromosome painting in healthy individuals who have not been occupationally or accidentally exposed to radiation or chemicals, and who have not received chemo- or radiotherapy. To date we have analyzed 15 umbilical cord bloods as well as peripheral blood samples from 83 adults aged up to 77 years. Because stable aberrations are rare in unexposed people, we have scored large numbers of cells from each subject. Thus far we have analyzed the equivalent of more than 78,000 metaphases from these 83 people, and have observed an average of 0.75% of cells with translocations or stable insertions. A significant curvilinear relationship with age is apparent (R{sup 2} = 0.69, p <0.00001). No effect with smoking was seen.

  8. [Individual difference in making temporal comparisons: development of Temporal Comparison Orientation Scale].

    PubMed

    Namikawa, Tsutomu

    2011-02-01

    This study developed the Temporal Comparison Orientation Scale and investigated its reliability and validity. Study 1 (N = 481) examined the factor structure and correlations with other related scales (self-consciousness scale; revaluation tendency scale; self-esteem scale; depression scale; social comparison orientation scale). The results suggested that the Temporal Comparison Orientation Scale had good reliability and validity. Study 2 examined the relationship between temporal comparison orientation and affect generated by temporal comparisons. The results showed that individuals high in temporal comparison orientation experienced more negative affect after upward and downward comparisons than individuals low in temporal comparison orientation. The possible uses and limitations of the scale were discussed. PMID:21400863

  9. Compact, Highly Stable Ion Atomic Clock

    NASA Technical Reports Server (NTRS)

    Prestage, John

    2008-01-01

    A mercury-ion clock now at the breadboard stage of development (see figure) has a stability comparable to that of a hydrogen-maser clock: In tests, the clock exhibited an Allan deviation of between 2 x 10(exp -13) and 3 x 10(exp -13) at a measurement time of 1 second, averaging to about 10(exp -15) at 1 day. However, the clock occupies a volume of only about 2 liters . about a hundredth of the volume of a hydrogen-maser clock. The ion-handling parts of the apparatus are housed in a sealed vacuum tube, wherein only a getter pump is used to maintain the vacuum. Hence, this apparatus is a prototype of a generation of small, potentially portable high-precision clocks for diverse ground- and space-based navigation and radio science applications. Furthermore, this new ion-clock technology is about 100 times more stable and precise than the rubidium atomic clocks currently in use in the NAV STAR GPS Earth-orbiting satellites. In this clock, mercury ions are shuttled between a quadrupole and a 16-pole linear radio-frequency trap. In the quadrupole trap, the ions are tightly confined and optical state selection from a Hg-202 radio-frequency-discharge ultraviolet lamp is carried out. In the 16-pole trap, the ions are more loosely confined and atomic transitions resonant at frequency of about 40.507 GHz are interrogated by use of a microwave beam at that frequency. The trapping of ions effectively eliminates the frequency pulling caused by wall collisions inherent to gas-cell clocks. The shuttling of the ions between the two traps enables separation of the state-selection process from the clock microwave- resonance process, so that each of these processes can be optimized independently of the other. The basic ion-shuttling, two-trap scheme as described thus far is not new: it has been the basis of designs of prior larger clocks. The novelty of the present development lies in major redesigns of its physics package (the ion traps and the vacuum and optical subsystems) to effect

  10. Delayed-choice Measurement and Temporal Nonlocality

    NASA Astrophysics Data System (ADS)

    Kim, Ilki; Mahler, Günter

    2001-02-01

    We study for a composite quantum system with a quantum Turing architecture the temporal non-locality of quantum mechanics by using the temporal Bell inequality, which will be derived for a discretized network dynamics by identifying the subsystem indices with (discrete) parameter time. However, the direct "observation" of the quantum system will lead to no violation of the temporal Bell inequality and to consistent histories of any subsystem. Its violation can be demonstrated, though, for a delayedchoice measurement

  11. Stable water isotope and surface heat flux simulation using ISOLSM: Evaluation against in-situ measurements

    NASA Astrophysics Data System (ADS)

    Cai, Mick Y.; Wang, Lixin; Parkes, Stephen D.; Strauss, Josiah; McCabe, Matthew F.; Evans, Jason P.; Griffiths, Alan D.

    2015-04-01

    The stable isotopes of water are useful tracers of water sources and hydrological processes. Stable water isotope-enabled land surface modeling is a relatively new approach for characterizing the hydrological cycle, providing spatial and temporal variability for a number of hydrological processes. At the land surface, the integration of stable water isotopes with other meteorological measurements can assist in constraining surface heat flux estimates and discriminate between evaporation (E) and transpiration (T). However, research in this area has traditionally been limited by a lack of continuous in-situ isotopic observations. Here, the National Centre for Atmospheric Research stable isotope-enabled Land Surface Model (ISOLSM) is used to simulate the water and energy fluxes and stable water isotope variations. The model was run for a period of one month with meteorological data collected from a coastal sub-tropical site near Sydney, Australia. The modeled energy fluxes (latent heat and sensible heat) agreed reasonably well with eddy covariance observations, indicating that ISOLSM has the capacity to reproduce observed flux behavior. Comparison of modeled isotopic compositions of evapotranspiration (ET) against in-situ Fourier Transform Infrared spectroscopy (FTIR) measured bulk water vapor isotopic data (10 m above the ground), however, showed differences in magnitude and temporal patterns. The disparity is due to a small contribution from local ET fluxes to atmospheric boundary layer water vapor (∼1% based on calculations using ideal gas law) relative to that advected from the ocean for this particular site. Using ISOLSM simulation, the ET was partitioned into E and T with 70% being T. We also identified that soil water from different soil layers affected T and E differently based on the simulated soil isotopic patterns, which reflects the internal working of ISOLSM. These results highlighted the capacity of using the isotope-enabled models to discriminate

  12. Reclaimed mineland curve number response to temporal distribution of rainfall

    USGS Publications Warehouse

    Warner, R.C.; Agouridis, C.T.; Vingralek, P.T.; Fogle, A.W.

    2010-01-01

    The curve number (CN) method is a common technique to estimate runoff volume, and it is widely used in coal mining operations such as those in the Appalachian region of Kentucky. However, very little CN data are available for watersheds disturbed by surface mining and then reclaimed using traditional techniques. Furthermore, as the CN method does not readily account for variations in infiltration rates due to varying rainfall distributions, the selection of a single CN value to encompass all temporal rainfall distributions could lead engineers to substantially under- or over-size water detention structures used in mining operations or other land uses such as development. Using rainfall and runoff data from a surface coal mine located in the Cumberland Plateau of eastern Kentucky, CNs were computed for conventionally reclaimed lands. The effects of temporal rainfall distributions on CNs was also examined by classifying storms as intense, steady, multi-interval intense, or multi-interval steady. Results indicate that CNs for such reclaimed lands ranged from 62 to 94 with a mean value of 85. Temporal rainfall distributions were also shown to significantly affect CN values with intense storms having significantly higher CNs than multi-interval storms. These results indicate that a period of recovery is present between rainfall bursts of a multi-interval storm that allows depressional storage and infiltration rates to rebound. ?? 2010 American Water Resources Association.

  13. Spatio-Temporal Analysis of Surface Soil Moisture in Evaluating Ground Truth Monitoring Sites for Remotely Sensed Observations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil moisture is an intrinsic state variable that varies considerably in space and time. Although soil moisture is highly variable, repeated measurements of soil moisture at the field or small watershed scale can often reveal certain locations as being temporally stable and representative of the are...

  14. Temporal Processing Deficits in Middle Age

    PubMed Central

    Mamo, Sara K.; Buss, Emily; Hall, Joseph W.

    2015-01-01

    Purpose The purpose of this brief report is to provide a synopsis of recent work, primarily from the authors' laboratory, that points to the emergence of temporal processing deficits relatively early in the aging process. Method The approach taken was to provide a descriptive summary of selected published and current experiments focusing on the processing of temporal envelopes and fine structure. Conclusion Deficits in both temporal envelope and temporal fine structure processing are evident during middle age even while audiometric hearing sensitivity remains normal. PMID:25768652

  15. Temporal Lobe Epilepsy Surgery Failures: A Review

    PubMed Central

    Harroud, Adil; Bouthillier, Alain; Weil, Alexander G.; Nguyen, Dang Khoa

    2012-01-01

    Patients with temporal lobe epilepsy (TLE) are refractory to antiepileptic drugs in about 30% of cases. Surgical treatment has been shown to be beneficial for the selected patients but fails to provide a seizure-free outcome in 20–30% of TLE patients. Several reasons have been identified to explain these surgical failures. This paper will address the five most common causes of TLE surgery failure (a) insufficient resection of epileptogenic mesial temporal structures, (b) relapse on the contralateral mesial temporal lobe, (c) lateral temporal neocortical epilepsy, (d) coexistence of mesial temporal sclerosis and a neocortical lesion (dual pathology); and (e) extratemporal lobe epilepsy mimicking TLE or temporal plus epilepsy. Persistence of epileptogenic mesial structures in the posterior temporal region and failure to distinguish mesial and lateral temporal epilepsy are possible causes of seizure persistence after TLE surgery. In cases of dual pathology, failure to identify a subtle mesial temporal sclerosis or regions of cortical microdysgenesis is a likely explanation for some surgical failures. Extratemporal epilepsy syndromes masquerading as or coexistent with TLE result in incomplete resection of the epileptogenic zone and seizure relapse after surgery. In particular, the insula may be an important cause of surgical failure in patients with TLE. PMID:22934162

  16. High-Order Energy Stable WENO Schemes

    NASA Technical Reports Server (NTRS)

    Yamaleev, Nail K.; Carpenter, Mark H.

    2008-01-01

    A new third-order Energy Stable Weighted Essentially NonOscillatory (ESWENO) finite difference scheme for scalar and vector linear hyperbolic equations with piecewise continuous initial conditions is developed. The new scheme is proven to be stable in the energy norm for both continuous and discontinuous solutions. In contrast to the existing high-resolution shock-capturing schemes, no assumption that the reconstruction should be total variation bounded (TVB) is explicitly required to prove stability of the new scheme. A rigorous truncation error analysis is presented showing that the accuracy of the 3rd-order ESWENO scheme is drastically improved if the tuning parameters of the weight functions satisfy certain criteria. Numerical results show that the new ESWENO scheme is stable and significantly outperforms the conventional third-order WENO finite difference scheme of Jiang and Shu in terms of accuracy, while providing essentially nonoscillatory solutions near strong discontinuities.

  17. Stable Isotope Enrichment Capabilities at ORNL

    SciTech Connect

    Egle, Brian; Aaron, W Scott; Hart, Kevin J

    2013-01-01

    The Oak Ridge National Laboratory (ORNL) and the US Department of Energy Nuclear Physics Program have built a high-resolution Electromagnetic Isotope Separator (EMIS) as a prototype for reestablishing a US based enrichment capability for stable isotopes. ORNL has over 60 years of experience providing enriched stable isotopes and related technical services to the international accelerator target community, as well as medical, research, industrial, national security, and other communities. ORNL is investigating the combined use of electromagnetic and gas centrifuge isotope separation technologies to provide research quantities (milligram to several kilograms) of enriched stable isotopes. In preparation for implementing a larger scale production facility, a 10 mA high-resolution EMIS prototype has been built and tested. Initial testing of the device has simultaneously collected greater than 98% enriched samples of all the molybdenum isotopes from natural abundance feedstock.

  18. Concentration of stable elements in food products

    SciTech Connect

    Montford, M.A.; Shank, K.E.; Hendricks, C.; Oakes, T.W.

    1980-01-01

    Food samples were taken from commercial markets and analyzed for stable element content. The concentrations of most stable elements (Ag, Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, La, Mg, Mn, Mo, Na, Rb, Sb, Sc, Se, Sr, Ta, Th, Ti, V, Zn, Zr) were determined using multiple-element neutron activation analysis, while the concentrations of other elements (Cd, Hg, Ni, Pb) were determined using atomic absorption. The relevance of the concentrations found are noted in relation to other literature values. An earlier study was extended to include the determination of the concentration of stable elements in home-grown products in the vicinity of the Oak Ridge National Laboratory. Comparisons between the commercial and local food-stuff values are discussed.

  19. Stable isotope and elemental analysis in ants.

    PubMed

    Smith, Chris R; Tillberg, Chadwick V

    2009-07-01

    Over the past 20 yr, the use of stable isotopes to infer feeding ecology and the examination of how energetic and elemental exchanges are affected by and affect life (ecological stoichiometry) have gained momentum. The ecological diversity of ants makes them interesting models to explore dietary ecology and their role in food webs. Moreover, their ecological dominance in most habitats facilitates sampling. The protocol described here will produce samples adequate for submission to most labs that specialize in high-throughput analysis of stable isotopes; one should check with any particular lab for specific submission instructions. Note, however, that this protocol is designed specifically for the quantification of the natural abundance of stable isotopes; it does not cover the preparation of trace samples. PMID:20147207

  20. Low work function, stable thin films

    DOEpatents

    Dinh, Long N.; McLean, II, William; Balooch, Mehdi; Fehring, Jr., Edward J.; Schildbach, Marcus A.

    2000-01-01

    Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to 500.degree. C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.

  1. High-Order Energy Stable WENO Schemes

    NASA Technical Reports Server (NTRS)

    Yamaleev, Nail K.; Carpenter, Mark H.

    2009-01-01

    A third-order Energy Stable Weighted Essentially Non-Oscillatory (ESWENO) finite difference scheme developed by Yamaleev and Carpenter was proven to be stable in the energy norm for both continuous and discontinuous solutions of systems of linear hyperbolic equations. Herein, a systematic approach is presented that enables 'energy stable' modifications for existing WENO schemes of any order. The technique is demonstrated by developing a one-parameter family of fifth-order upwind-biased ESWENO schemes; ESWENO schemes up to eighth order are presented in the appendix. New weight functions are also developed that provide (1) formal consistency, (2) much faster convergence for smooth solutions with an arbitrary number of vanishing derivatives, and (3) improved resolution near strong discontinuities.

  2. The Temporal Configuration of Airline Networks

    NASA Technical Reports Server (NTRS)

    Burghouwt, Guillaume; deWit, Jaap

    2003-01-01

    The deregulation of US aviation in 1978 resulted in the reconfiguration of airline networks into hub-and-spoke systems, spatially concentrated around a small number of central airports or 'hubs' through which an airline operates a number of daily waves of flights. A hub-and-spoke network requires a concentration of traffic in both space and time. In contrast to the U.S. airlines, European airlines had entered the phase of spatial network concentration long before deregulation. Bilateral negotiation of traffic fights between governments forced European airlines to focus their networks spatially on small number of 'national' airports. In general, these star-shaped networks were not coordinated in time. Transfer opportunities at central airports were mostly created 'by accident'. With the deregulation of the EU air transport market from 1988 on, a second phase of airline network concentration started. European airlines concentrated their networks in time by adopting or intensifying wave-system structures in their flight schedules. Temporal concentration may increase the competitive position of the network in a deregulated market because of certain cost and demand advantages.

  3. Spiking neuron model for temporal sequence recognition.

    PubMed

    Byrnes, Sean; Burkitt, Anthony N; Grayden, David B; Meffin, Hamish

    2010-01-01

    A biologically inspired neuronal network that stores and recognizes temporal sequences of symbols is described. Each symbol is represented by excitatory input to distinct groups of neurons (symbol pools). Unambiguous storage of multiple sequences with common subsequences is ensured by partitioning each symbol pool into subpools that respond only when the current symbol has been preceded by a particular sequence of symbols. We describe synaptic structure and neural dynamics that permit the selective activation of subpools by the correct sequence. Symbols may have varying durations of the order of hundreds of milliseconds. Physiologically plausible plasticity mechanisms operate on a time scale of tens of milliseconds; an interaction of the excitatory input with periodic global inhibition bridges this gap so that neural events representing successive symbols occur on this much faster timescale. The network is shown to store multiple overlapping sequences of events. It is robust to variation in symbol duration, it is scalable, and its performance degrades gracefully with perturbation of its parameters. PMID:19842991

  4. Determining Spatio-Temporal Cadastral Data Requirement for Infrastructure of Ladm for Turkey

    NASA Astrophysics Data System (ADS)

    Alkan, M.; Polat, Z. A.

    2016-06-01

    Nowadays, the nature of land title and cadastral (LTC) data in the Turkey is dynamic from a temporal perspective which depends on the LTC operations. Functional requirements with respect to the characteristics are investigated based upon interviews of professionals in public and private sectors. These are; Legal authorities, Land Registry and Cadastre offices, Highway departments, Foundations, Ministries of Budget, Transportation, Justice, Public Works and Settlement, Environment and Forestry, Agriculture and Rural Affairs, Culture and Internal Affairs, State Institute of Statistics (SIS), execution offices, tax offices, real estate offices, private sector, local governments and banks. On the other hand, spatio-temporal LTC data very important component for creating infrastructure of Land Administration Model (LADM). For this reason, spatio-temporal LTC data needs for LADM not only updated but also temporal. The investigations ended up with determine temporal analyses of LTC data, traditional LTC system and tracing temporal analyses in traditional LTC system. In the traditional system, the temporal analyses needed by all these users could not be performed in a rapid and reliable way. The reason for this is that the traditional LTC system is a manual archiving system. The aims and general contents of this paper: (1) define traditional LTC system of Turkey; (2) determining the need for spatio-temporal LTC data and analyses for core domain model for LADM. As a results of temporal and spatio-temporal analysis LTC data needs, new system design is important for the Turkish LADM model. Designing and realizing an efficient and functional Temporal Geographic Information Systems (TGIS) is inevitable for the Turkish LADM core infrastructure. Finally this paper outcome is creating infrastructure for design and develop LADM for Turkey.

  5. Stable lithium electrodeposition in liquid and nanoporous solid electrolytes.

    PubMed

    Lu, Yingying; Tu, Zhengyuan; Archer, Lynden A

    2014-10-01

    Rechargeable lithium, sodium and aluminium metal-based batteries are among the most versatile platforms for high-energy, cost-effective electrochemical energy storage. Non-uniform metal deposition and dendrite formation on the negative electrode during repeated cycles of charge and discharge are major hurdles to commercialization of energy-storage devices based on each of these chemistries. A long-held view is that unstable electrodeposition is a consequence of inherent characteristics of these metals and their inability to form uniform electrodeposits on surfaces with inevitable defects. We report on electrodeposition of lithium in simple liquid electrolytes and in nanoporous solids infused with liquid electrolytes. We find that simple liquid electrolytes reinforced with halogenated salt blends exhibit stable long-term cycling at room temperature, often with no signs of deposition instabilities over hundreds of cycles of charge and discharge and thousands of operating hours. We rationalize these observations with the help of surface energy data for the electrolyte/lithium interface and impedance analysis of the interface during different stages of cell operation. Our findings provide support for an important recent theoretical prediction that the surface mobility of lithium is significantly enhanced in the presence of lithium halide salts. Our results also show that a high electrolyte modulus is unnecessary for stable electrodeposition of lithium. PMID:25108613

  6. Temporal Interactions between Cortical Rhythms

    PubMed Central

    Roopun, Anita K.; Kramer, Mark A.; Carracedo, Lucy M.; Kaiser, Marcus; Davies, Ceri H.; Traub, Roger D.; Kopell, Nancy J.; Whittington, Miles A.

    2008-01-01

    Multiple local neuronal circuits support different, discrete frequencies of network rhythm in neocortex. Relationships between different frequencies correspond to mechanisms designed to minimise interference, couple activity via stable phase interactions, and control the amplitude of one frequency relative to the phase of another. These mechanisms are proposed to form a framework for spectral information processing. Individual local circuits can also transform their frequency through changes in intrinsic neuronal properties and interactions with other oscillating microcircuits. Here we discuss a frequency transformation in which activity in two co-active local circuits may combine sequentially to generate a third frequency whose period is the concatenation sum of the original two. With such an interaction, the intrinsic periodicity in each component local circuit is preserved – alternate, single periods of each original rhythm form one period of a new frequency – suggesting a robust mechanism for combining information processed on multiple concurrent spatiotemporal scales. PMID:19225587

  7. Utilizing AI in Temporal, Spatial, and Resource Scheduling

    NASA Technical Reports Server (NTRS)

    Stottler, Richard; Kalton, Annaka; Bell, Aaron

    2006-01-01

    Aurora is a software system enabling the rapid, easy solution of complex scheduling problems involving spatial and temporal constraints among operations and scarce resources (such as equipment, workspace, and human experts). Although developed for use in the International Space Station Processing Facility, Aurora is flexible enough that it can be easily customized for application to other scheduling domains and adapted as the requirements change or become more precisely known over time. Aurora s scheduling module utilizes artificial-intelligence (AI) techniques to make scheduling decisions on the basis of domain knowledge, including knowledge of constraints and their relative importance, interdependencies among operations, and possibly frequent changes in governing schedule requirements. Unlike many other scheduling software systems, Aurora focuses on resource requirements and temporal scheduling in combination. For example, Aurora can accommodate a domain requirement to schedule two subsequent operations to locations adjacent to a shared resource. The graphical interface allows the user to quickly visualize the schedule and perform changes reflecting additional knowledge or alterations in the situation. For example, the user might drag the activity corresponding to the start of operations to reflect a late delivery.

  8. Stable Tricyclic Antitubercular Ozonides Derived from Artemisinin.

    PubMed

    Chaudhary, Sandeep; Sharma, Vashundhra; Jaiswal, Pradeep K; Gaikwad, Anil N; Sinha, Sudhir K; Puri, Sunil K; Sharon, Ashoke; Maulik, Prakas R; Chaturvedi, Vinita

    2015-10-16

    New, highly stable tricyclic antitubercular ozonides 9 and 10 derived from artemisinin are reported in 39 and 9% yields, respectively. The ozonide groups of 9 and 10 were found to be stable under strong basic and acidic conditions. The absolute configuration of ozonides 9 was confirmed by X-ray crystallography. Ozonide 10 shows promising antitubercular activity against M. tuberculosis H37Ra and M. tuberculosis H37Rv with MIC values of 0.39 and 3.12 μg/mL, respectively. PMID:26430796

  9. Stable isotopes in Lithuanian bioarcheological material

    NASA Astrophysics Data System (ADS)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger

  10. Stable isotope labeling methods for DNA.

    PubMed

    Nelissen, Frank H T; Tessari, Marco; Wijmenga, Sybren S; Heus, Hans A

    2016-08-01

    NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis. PMID:27573183

  11. Using consistent subcuts for detecting stable properties

    NASA Technical Reports Server (NTRS)

    Marzullo, Keith; Sabel, Laura

    1992-01-01

    We present a general protocol for detecting whether a property holds in a distributed system, where the property is a member of a subclass of stable properties we call the locally stable properties. Our protocol is based on a decentralized method for constructing a maximal subset of the local states that are mutually consistent, which in turn is based on a weakened version of vectored time stamps. The structure of our protocol lends itself to refinement, and we demonstrate its utility by deriving some specialized property-detection protocols, including two previously known protocols that are known to be effective.

  12. Temporal Cognition: A Key Ingredient of Intelligent Systems

    PubMed Central

    Maniadakis, Michail; Trahanias, Panos

    2011-01-01

    Experiencing the flow of time is an important capacity of biological systems that is involved in many ways in the daily activities of humans and animals. However, in the field of robotics, the key role of time in cognition is not adequately considered in contemporary research, with artificial agents focusing mainly on the spatial extent of sensory information, almost always neglecting its temporal dimension. This fact significantly obstructs the development of high-level robotic cognitive skills, as well as the autonomous and seamless operation of artificial agents in human environments. Taking inspiration from biological cognition, the present work puts forward time perception as a vital capacity of artificial intelligent systems and contemplates the research path for incorporating temporal cognition in the repertoire of robotic skills. PMID:21954384

  13. Temporal cognition: a key ingredient of intelligent systems.

    PubMed

    Maniadakis, Michail; Trahanias, Panos

    2011-01-01

    Experiencing the flow of time is an important capacity of biological systems that is involved in many ways in the daily activities of humans and animals. However, in the field of robotics, the key role of time in cognition is not adequately considered in contemporary research, with artificial agents focusing mainly on the spatial extent of sensory information, almost always neglecting its temporal dimension. This fact significantly obstructs the development of high-level robotic cognitive skills, as well as the autonomous and seamless operation of artificial agents in human environments. Taking inspiration from biological cognition, the present work puts forward time perception as a vital capacity of artificial intelligent systems and contemplates the research path for incorporating temporal cognition in the repertoire of robotic skills. PMID:21954384

  14. Temporal variability of particulate organic carbon in the lower Changjiang (Yangtze River) in the post-Three Gorges Dam period: Links to anthropogenic and climate impacts

    NASA Astrophysics Data System (ADS)

    Wu, Ying; Bao, Hongyan; Yu, Hao; Zhang, Jing; Kattner, Gerhard

    2015-11-01

    Suspended particles from the lower Changjiang were collected monthly from 2003 to 2011, which corresponds to the three construction periods of the Three Gorges Dam. Organic carbon (%OC), organic carbon to total nitrogen molar ratio, stable carbon isotope, and terrestrial biomarkers were examined. Rating curve studies were applied for the temporal trend analysis. The composition of particulate lignin phenols exhibited clear annual and periodic variations but only minor seasonal changes. Lignin phenol ratios (vanillyl/syringyl and cinnamyl/vanillyl) indicated that the terrigenous organic matter (OM) was primarily composed of woody and nonwoody tissue derived from angiosperm plants. The low-lignin phenol yields (Λ8) in combination with higher acid to aldehyde ratios reflected a substantial contribution from soil OM to the particle samples or modifications during river transport. The temporal shift of the lignin phenol vegetation index with the sediment load during the flood seasons revealed particulate organic matter (POM) erosion from soils and the impact of hydrodynamic processes. The dam operations affected the seasonal variability of terrigenous OM fluxes, although the covariation of lignin and sediment loads with discharged water implies that unseasonal extreme conditions and climate change most likely had larger influences, because decreases in the sediment load and lignin flux alter the structure and composition of particulate OM (POM) on interannual time scales, indicating that they may be driven by climate variability. The modification of the composition and structure of POM will have significant impacts on regional carbon cycles and marine ecosystems.

  15. An inverter-based capacitive trans-impedance amplifier readout with offset cancellation and temporal noise reduction for IR focal plane array

    NASA Astrophysics Data System (ADS)

    Chen, Hsin-Han; Hsieh, Chih-Cheng

    2013-09-01

    This paper presents a readout integrated circuit (ROIC) with inverter-based capacitive trans-impedance amplifier (CTIA) and pseudo-multiple sampling technique for infrared focal plane array (IRFPA). The proposed inverter-based CTIA with a coupling capacitor [1], executing auto-zeroing technique to cancel out the varied offset voltage from process variation, is used to substitute differential amplifier in conventional CTIA. The tunable detector bias is applied from a global external bias before exposure. This scheme not only retains stable detector bias voltage and signal injection efficiency, but also reduces the pixel area as well. Pseudo-multiple sampling technique [2] is adopted to reduce the temporal noise of readout circuit. The noise reduction performance is comparable to the conventional multiple sampling operation without need of longer readout time proportional to the number of samples. A CMOS image sensor chip with 55×65 pixel array has been fabricated in 0.18um CMOS technology. It achieves a 12um×12um pixel size, a frame rate of 72 fps, a power-per-pixel of 0.66uW/pixel, and a readout temporal noise of 1.06mVrms (16 times of pseudo-multiple sampling), respectively.

  16. Plant diversity increases spatio-temporal niche complementarity in plant-pollinator interactions.

    PubMed

    Venjakob, Christine; Klein, Alexandra-Maria; Ebeling, Anne; Tscharntke, Teja; Scherber, Christoph

    2016-04-01

    Ongoing biodiversity decline impairs ecosystem processes, including pollination. Flower visitation, an important indicator of pollination services, is influenced by plant species richness. However, the spatio-temporal responses of different pollinator groups to plant species richness have not yet been analyzed experimentally. Here, we used an experimental plant species richness gradient to analyze plant-pollinator interactions with an unprecedented spatio-temporal resolution. We observed four pollinator functional groups (honeybees, bumblebees, solitary bees, and hoverflies) in experimental plots at three different vegetation strata between sunrise and sunset. Visits were modified by plant species richness interacting with time and space. Furthermore, the complementarity of pollinator functional groups in space and time was stronger in species-rich mixtures. We conclude that high plant diversity should ensure stable pollination services, mediated via spatio-temporal niche complementarity in flower visitation. PMID:27069585

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  18. Towards operational multisensor registration

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J. M.; Kwok, Ronald; Curlander, John C.

    1991-01-01

    To use data from a number of different remote sensors in a synergistic manner, a multidimensional analysis of the data is necessary. However, prior to this analysis, processing to correct for the systematic geometric distortion characteristic of each sensor is required. Furthermore, the registration process must be fully automated to handle a large volume of data and high data rates. A conceptual approach towards an operational multisensor registration algorithm is presented. The performance requirements of the algorithm are first formulated given the spatially, temporally, and spectrally varying factors that influence the image characteristics and the science requirements of various applications. Several registration techniques that fit within the structure of this algorithm are also presented. Their performance was evaluated using a multisensor test data set assembled from LANDSAT TM, SEASAT, SIR-B, Thermal Infrared Multispectral Scanner (TIMS), and SPOT sensors.

  19. Temporal Ontologies for Geoscience: Alignment Challenges

    NASA Astrophysics Data System (ADS)

    Cox, S. J. D.

    2014-12-01

    Time is a central concept in geoscience. Geologic histories are composed of sequences of geologic processes and events. Calibration of their timing ties a local history into a broader context, and enables correlation of events between locations. The geologic timescale is standardized in the International Chronostratigraphic Chart, which specifies interval names, and calibrations for the ages of the interval boundaries. Time is also a key concept in the world at large. A number of general purpose temporal ontologies have been developed, both stand-alone and as parts of general purpose or upper ontologies. A temporal ontology for geoscience should apply or extend a suitable general purpose temporal ontology. However, geologic time presents two challenges: Geology involves greater spans of time than in other temporal ontologies, inconsistent with the year-month-day/hour-minute-second formalization that is a basic assumption of most general purpose temporal schemes; The geologic timescale is a temporal topology. Its calibration in terms of an absolute (numeric) scale is a scientific issue in its own right supporting a significant community. In contrast, the general purpose temporal ontologies are premised on exact numeric values for temporal position, and do not allow for temporal topology as a primary structure. We have developed an ontology for the geologic timescale to account for these concerns. It uses the ISO 19108 distinctions between different types of temporal reference system, also linking to an explicit temporal topology model. Stratotypes used in the calibration process are modelled as sampling-features following the ISO 19156 Observations and Measurements model. A joint OGC-W3C harmonization project is underway, with standardization of the W3C OWL-Time ontology as one of its tasks. The insights gained from the geologic timescale ontology will assist in development of a general ontology capable of modelling a richer set of use-cases from geoscience.

  20. Spatio-temporal coherence of free-electron laser radiation in the extreme ultraviolet determined by a Michelson interferometer

    SciTech Connect

    Hilbert, V.; Rödel, C.; Zastrau, U.; Brenner, G.; Düsterer, S.; Dziarzhytski, S.; Harmand, M.; Przystawik, A.; Redlin, H.; Toleikis, S.; Döppner, T.; Ma, T.; Fletcher, L.; Förster, E.; Glenzer, S. H.; Lee, H. J.; Hartley, N. J.; Kazak, L.; Komar, D.; Skruszewicz, S.; and others

    2014-09-08

    A key feature of extreme ultraviolet (XUV) radiation from free-electron lasers (FELs) is its spatial and temporal coherence. We measured the spatio-temporal coherence properties of monochromatized FEL pulses at 13.5 nm using a Michelson interferometer. A temporal coherence time of (59±8) fs has been determined, which is in good agreement with the spectral bandwidth given by the monochromator. Moreover, the spatial coherence in vertical direction amounts to about 15% of the beam diameter and about 12% in horizontal direction. The feasibility of measuring spatio-temporal coherence properties of XUV FEL radiation using interferometric techniques advances machine operation and experimental studies significantly.

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  2. Large-eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Zhou, Bowen

    and reconstruction LES framework. The DRM is a mixed model that consists of subgrid scale (SGS) and resolved subfilter scale (RSFS) components. The RSFS portion is represented by a scale-similarity model that allows for backscatter of energy from the SFS to the mean flow. Compared to conventional closures, the DRM is able to sustain resolved turbulence under moderate stability at coarser resolution (thus saving computational resources). The DRM performs equally well at fine resolution. Under strong stability, the DRM simulates an intermittently turbulent SBL, whereas conventional closures predict false laminar flows. The improved simulation methodology of the SBL has many potential applications in the area of wind energy, numerical weather prediction, pollution modeling and so on. The SBL is first simulated over idealized flat terrain with prescribed forcings and periodic lateral boundaries. A wide range of stability regimes, from weakly to strongly stable conditions, is tested to evaluate model performance. Under strongly stable conditions, intermittency due to mean shear and turbulence interactions is simulated and analyzed. Furthermore, results of the strongly stable SBL are used to improve wind farm siting and nighttime operations. Moving away from the idealized setting, the SBL is simulated over relatively flat terrain at a Kansas site over the Great Plains, where the Cooperative Atmospheric-Surface Exchange Study -- 1999 (CASES-99) took place. The LES obtains realistic initial and lateral boundary conditions from a meso-scale model reanalysis through a grid nesting procedure. Shear-instability induced intermittency observed on the night of Oct 5th during CASES-99 is reproduced to good temporal and magnitude agreement. The LES locates the origin of the shear-instability waves in a shallow upwind valley, and uncovers the intermittency mechanism to be wave breaking over a standing wave (formed over a stagnant cold-air bubble) across the valley. Finally, flow over

  3. Exact simulation of max-stable processes

    PubMed Central

    Dombry, Clément; Engelke, Sebastian; Oesting, Marco

    2016-01-01

    Max-stable processes play an important role as models for spatial extreme events. Their complex structure as the pointwise maximum over an infinite number of random functions makes their simulation difficult. Algorithms based on finite approximations are often inexact and computationally inefficient. We present a new algorithm for exact simulation of a max-stable process at a finite number of locations. It relies on the idea of simulating only the extremal functions, that is, those functions in the construction of a max-stable process that effectively contribute to the pointwise maximum. We further generalize the algorithm by Dieker & Mikosch (2015) for Brown–Resnick processes and use it for exact simulation via the spectral measure. We study the complexity of both algorithms, prove that our new approach via extremal functions is always more efficient, and provide closed-form expressions for their implementation that cover most popular models for max-stable processes and multivariate extreme value distributions. For simulation on dense grids, an adaptive design of the extremal function algorithm is proposed. PMID:27279659

  4. UNCERTAINTY IN SOURCE PARTITIONING USING STABLE ISOTOPES

    EPA Science Inventory

    Stable isotope analyses are often used to quantify the contribution of multiple sources to a mixture, such as proportions of food sources in an animal's diet, C3 vs. C4 plant inputs to soil organic carbon, etc. Linear mixing models can be used to partition two sources with a sin...

  5. Substitution of stable isotopes in Chlorella

    NASA Technical Reports Server (NTRS)

    Flaumenhaft, E.; Katz, J. J.; Uphaus, R. A.

    1969-01-01

    Replacement of biologically important isotopes in the alga Chlorella by corresponding heavier stable isotopes produces increasingly greater deviations from the normal cell size and changes the quality and distribution of certain cellular components. The usefulness of isotopically altered organisms increases interest in the study of such permuted organisms.

  6. Stable Fly Project in Campo Grande, Brazil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Andrew Li, Jerry Hogsette, and Adalberto Pérez de León, all USDA-ARS, and Lane Foil, LSU, are collaborating as consultants on an Embrapa-funded research project for the control of large stable fly populations associated with sugar cane production in Brazil. Our Brazilian counterpart, Dr. Paulo Cança...

  7. Dynamically stable magnetic suspension/bearing system

    DOEpatents

    Post, Richard F.

    1996-01-01

    A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw's Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements.

  8. Dynamically stable magnetic suspension/bearing system

    DOEpatents

    Post, R.F.

    1996-02-27

    A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements. 32 figs.

  9. Correlated Temporal and Spectral Variability

    NASA Technical Reports Server (NTRS)

    Swank, Jean H.

    2007-01-01

    The variability of neutron star and black hole X-ray sources has several dimensions, because of the roles played by different important time-scales. The variations on time scales of hours, weeks, and months, ranging from 50% to orders of magnitude, arise out of changes in the flow in the disk. The most important driving forces for those changes are probably various possible instabilities in the disk, though there may be effects with other dominant causes. The changes in the rate of flow appear to be associated with changes in the flow's configuration, as the accreting material approaches the compact object, for there are generally correlated changes in both the Xray spectra and the character of the faster temporal variability. There has been a lot of progress in tracking these correlations, both for Z and Atoll neutron star low-mass X-ray binaries, and for black hole binaries. I will discuss these correlations and review briefly what they tell us about the physical states of the systems.

  10. Retinal pathways influence temporal niche

    PubMed Central

    Doyle, Susan E.; Yoshikawa, Tomoko; Hillson, Holly; Menaker, Michael

    2008-01-01

    In mammals, light input from the retina entrains central circadian oscillators located in the suprachiasmatic nuclei (SCN). The phase of circadian activity rhythms with respect to the external light:dark cycle is reversed in diurnal and nocturnal species, although the phase of SCN rhythms relative to the light cycle remains unchanged. Neural mechanisms downstream from the SCN are therefore believed to determine diurnality or nocturnality. Here, we report a switch from nocturnal to diurnal entrainment of circadian activity rhythms in double-knockout mice lacking the inner-retinal photopigment melanopsin (OPN4) and RPE65, a key protein used in retinal chromophore recycling. These mice retained only a small amount of rod function. The change in entrainment phase of Rpe65−/−;Opn4−/− mice was accompanied by a reversal of the rhythm of clock gene expression in the SCN and a reversal in acute masking effects of both light and darkness on activity, suggesting that the nocturnal to diurnal switch is due to a change in the neural response to light upstream from the SCN. A switch from nocturnal to diurnal activity rhythms was also found in wild-type mice transferred from standard intensity light:dark cycles to light:dark cycles in which the intensity of the light phase was reduced to scotopic levels. These results reveal a novel mechanism by which changes in retinal input can mediate acute temporal-niche switching. PMID:18695249

  11. Dynamic simulation of stable water isotopes during the last interglacial

    NASA Astrophysics Data System (ADS)

    Gierz, P.; Lohmann, G.; Brocas, W.; Felis, T.

    2014-12-01

    Using the novel isotope module of the global fully coupled climate model COSMOS, we simulate the climate of the last interglacial for three time slices at 120, 125, and 130 kiloyears before present. The inclusion of stable water isotopes allows us to not only have a comprehensive picture of the climate state during a warm interglacial, but also allows for a direct comparison with climate proxy records. We compare our simulation with isotope data gathered from fossilized corals, which have an excellent temporal resolution and well constrained dating. A model data comparison allows us to see that there was an enhanced seasonality of both temperature and rainfall during the Eemian. While the data tends to produce a stronger winter cooling than the model, we suggest that this may be due to an incomplete climatology, as the measurements taken from the coral only encompasses a few decades. If the data happens to fall during an usually cool decade, the mismatch could be rectified. Alternatively, the data may include the cooling signal associated with centennial scale cold stadials during the Eemian. We test this by performing a freshwater perturbation experiment during the peak interglacial, which causes a pronounced cooling at the core site while the ocean circulation is depressed.

  12. Operational experience with the SLD CRID at the SLC

    NASA Astrophysics Data System (ADS)

    Abe, K.; Aston, D.; Baird, K.; Baltay, C.; Ben-David, R.; Bienz, T.; Caldwell, D. O.; Cavalli-Sforza, M.; Coller, J.; Coyne, D.; Dima, M.; d'Oliveira, A.; Hallewell, G.; Hasegawa, Y.; Huber, J.; Iwasaki, Y.; Jacques, P.; Johnson, R. A.; Kalelkar, M.; Kawahara, H.; Leith, D. W. G. S.; Liu, X.; Lu, A.; Manly, S.; Meadows, B.; Müller, G.; Muller, D.; Nagamine, T.; Narita, S.; Nussbaum, M.; Pavel, T. J.; Plano, R.; Ratcliff, B.; Rensing, P.; Sen, S.; Shank, J. T.; Shapiro, S.; Simopoulos, C.; Snyder, J.; Stamer, P.; Suekane, F.; Turk, J.; Va'vra, J.; Whitaker, J. S.; Williams, D. A.; Williams, S. H.; Willocq, S.; Wilson, R. J.; Word, G.; Yellin, S.; Yuta, H.

    1996-02-01

    We highlight some problems encountered and lessons learned in obtaining stable operation of the SLD CRID for the past four years. During the 1994-1995 run of the SLC, we achieved stable operation of liquid (C 6F 14) and gas ( {85% C 5F 12}/{15% N 2}) radiators with good UV transparency, and we regularly operate the TPCs with excellent drift lifetimes and good single photo-electron detection efficiency.

  13. Evaluation of Operationally Derived Aerosol Optical Depth from MSG-SEVIRI over Central Europe

    NASA Astrophysics Data System (ADS)

    Popp, C.; Riffler, M.; Emili, E.; Petitta, M.; Wunderle, S.

    2009-04-01

    Aerosol parameters derived from geostationary remote sensing instruments can complement those obtained from polar orbiting sensors (e.g. MODIS, MERIS, or AVHRR). The high scanning frequency of the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) on-board the Meteosat Second Generation (MSG) satellites of 15 minutes significantly broadens the potential diurnal coverage over Europe and Africa. Therefore, these data allow to better account for the occasionally high spatial and temporal variabilities of atmospheric aerosols, for instance in cases such as desert dust outbreaks, forest fires, or the evolution of high particulate matter concentrations during stable weather conditions. The aim of this study is to evaluate operationally derived aerosol optical depth maps based on imagery acquired by MSG-SEVIRI between December 2007 and November 2008. A one-channel multi-temporal approach is used in order to daily estimate aerosol optical depth for each slot between 6:12 and 18:12 UTC. The resulting SEVIRI AOD values are related to Sun photometer measurements from the Aerosol Robotic Network (AERONET). 22 AERONET sites within the study area of central Europe provide cloud-screened level1.5 data for the investigation period. Overall, nearly ten thousand instantaneous SEVIRI and Sun photometer AOD values are compared and a correlation of 0.75 as well as a root-mean-square-error of 0.07 is found. Further, about 75% of all SEVIRI AOD values fall within the MODIS expected error over land of +/-(0.05+0.15*AOD). Finally, the computed statistical parameters for each individual season do not vary strongly. Taken together, the performance of the operational SEVIRI AOD estimation is comparable to the ones based on data from sensors on-board polar orbiting satellites. Therefore, these aerosol information of high temporal frequency can be of great interest e.g. for tracking pollutant transport, for comparisons with aerosol modelling results, or for synergistic use with additional

  14. Temporal Processing, Attention, and Learning Disorders

    ERIC Educational Resources Information Center

    Landerl, Karin; Willburger, Edith

    2010-01-01

    In a large sample (N = 439) of literacy impaired and unimpaired elementary school children the predictions of the temporal processing theory of dyslexia were tested while controlling for (sub)clininal attentional deficits. Visual and Auditory Temporal Order Judgement were administered as well as three subtests of a standardized attention test. The…

  15. The Generative Temporality of Teaching under Revision

    ERIC Educational Resources Information Center

    Eacott, Scott; Hodges, Kimbalee

    2014-01-01

    What we have come to understand as education has a temporal dimension: the school year, progression based on time, timetables, and so on. Similarly, our understanding of teaching is framed by temporality, primarily through salary structures and an implicit coupling of performance with time in the field. We argue that this underlying generative…

  16. A Temporal Ratio Model of Memory

    ERIC Educational Resources Information Center

    Brown, Gordon D. A.; Neath, Ian; Chater, Nick

    2007-01-01

    A model of memory retrieval is described. The model embodies four main claims: (a) temporal memory--traces of items are represented in memory partly in terms of their temporal distance from the present; (b) scale-similarity--similar mechanisms govern retrieval from memory over many different timescales; (c) local distinctiveness--performance on a…

  17. Spatial and temporal variation in evapotranspiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial and temporal variation in evapotranspiration occurs at multiple scales as the result of several different spatial and temporal patterns in precipitation, soil water holding capacity, cloudiness (available energy), types of crops, and residue and tillage management practices. We have often as...

  18. Human Performance on the Temporal Bisection Task

    ERIC Educational Resources Information Center

    Kopec, Charles D.; Brody, Carlos D.

    2010-01-01

    The perception and processing of temporal information are tasks the brain must continuously perform. These include measuring the duration of stimuli, storing duration information in memory, recalling such memories, and comparing two durations. How the brain accomplishes these tasks, however, is still open for debate. The temporal bisection task,…

  19. Delay synchronization of temporal Boolean networks

    NASA Astrophysics Data System (ADS)

    Wei, Qiang; Xie, Cheng-jun; Liang, Yi; Niu, Yu-jun; Lin, Da

    2016-01-01

    This paper investigates the delay synchronization between two temporal Boolean networks base on semi-tensor product method, which improve complete synchronization. Necessary and sufficient conditions for delay synchronization are drawn base on algebraic expression of temporal Boolean networks. A example is presented to show the effectiveness of theoretical analysis.

  20. Preschoolers' Understanding of Temporal and Causal Relations.

    ERIC Educational Resources Information Center

    Sharp, Kay Colby

    1982-01-01

    Two experiments investigated psychological factors determining preschoolers' success or failure on a sequence-completion task involving temporal and causal ordering of events. Overall findings demonstrate that while preschoolers do understand temporal/causal relationships, their abilities are dependent on process variables demanded by the task…