Science.gov

Sample records for complex transient events

  1. Analyses Of Transient Events In Complex Valve and Feed Systems

    NASA Technical Reports Server (NTRS)

    Ahuja, Vineet; Hosangadi, Ashvin; Cavallo, Peter; Daines, Russell

    2005-01-01

    Valve systems in rocket propulsion systems and testing facilities are constantly subject to dynamic events resulting from the timing of valve motion leading to unsteady fluctuations in pressure and mass flow. Such events can also be accompanied by cavitation, resonance, system vibration leading to catastrophic failure. High-fidelity dynamic computational simulations of valve operation can yield important information of valve response to varying flow conditions. Prediction of transient behavior related to valve motion can serve as guidelines for valve scheduling, which is of crucial importance in engine operation and testing. In this paper, we present simulations of the diverse unsteady phenomena related to valve and feed systems that include valve stall, valve timing studies as well as cavitation instabilities in components utilized in the test loop.

  2. Transient complex peroxisomal interactions

    PubMed Central

    Bonekamp, Nina A.; Schrader, Michael

    2012-01-01

    Mitochondria and peroxisomes are ubiquitous subcellular organelles that fulfill essential metabolic functions, rendering them indispensable for human development and health. Both are highly dynamic organelles that can undergo remarkable changes in morphology and number to accomplish cellular needs. While mitochondrial dynamics are also regulated by frequent fusion events, the fusion of mature peroxisomes in mammalian cells remained a matter of debate. In our recent study, we clarified systematically that there is no complete fusion of mature peroxisomes analogous to mitochondria. Moreover, in contrast to key division components such as DLP1, Fis1 or Mff, mitochondrial fusion proteins were not localized to peroxisomes. However, we discovered and characterized novel transient, complex interactions between individual peroxisomes which may contribute to the homogenization of the often heterogeneous peroxisomal compartment, e.g., by distribution of metabolites, signals or other “molecular information” via interperoxisomal contact sites. PMID:23336019

  3. Studying transient events with Athena

    NASA Astrophysics Data System (ADS)

    O'Brien, Paul

    2016-07-01

    Athena is the second large mission selected in the ESA Cosmic Vision plan. With its large collecting area, high spectral-energy resolution (X-IFU instrument) and impressive grasp (WFI instrument), Athena will truly revolutionise X-ray astronomy. The most prodigious sources of high-energy photons are often transitory in nature. Athena will provide the sensitivity and spectral resolution coupled with rapid response to enable the study of the dynamic sky. Potential sources include: distant Gamma-Ray Bursts to probe the reionisation epoch and find 'missing' baryons in the cosmic web; tidal disruption events to reveal dormant supermassive and intermediate-mass black holes; and supernova explosions to understand progenitors and their environments. I will illustrate Athena's capabilities and show how it will be able to constrain the nature of explosive events.

  4. Complex Event Recognition Architecture

    NASA Technical Reports Server (NTRS)

    Fitzgerald, William A.; Firby, R. James

    2009-01-01

    Complex Event Recognition Architecture (CERA) is the name of a computational architecture, and software that implements the architecture, for recognizing complex event patterns that may be spread across multiple streams of input data. One of the main components of CERA is an intuitive event pattern language that simplifies what would otherwise be the complex, difficult tasks of creating logical descriptions of combinations of temporal events and defining rules for combining information from different sources over time. In this language, recognition patterns are defined in simple, declarative statements that combine point events from given input streams with those from other streams, using conjunction, disjunction, and negation. Patterns can be built on one another recursively to describe very rich, temporally extended combinations of events. Thereafter, a run-time matching algorithm in CERA efficiently matches these patterns against input data and signals when patterns are recognized. CERA can be used to monitor complex systems and to signal operators or initiate corrective actions when anomalous conditions are recognized. CERA can be run as a stand-alone monitoring system, or it can be integrated into a larger system to automatically trigger responses to changing environments or problematic situations.

  5. Single Event Transients in Linear Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Buchner, Stephen; McMorrow, Dale

    2005-01-01

    On November 5, 2001, a processor reset occurred on board the Microwave Anisotropy Probe (MAP), a NASA mission to measure the anisotropy of the microwave radiation left over from the Big Bang. The reset caused the spacecraft to enter a safehold mode from which it took several days to recover. Were that to happen regularly, the entire mission would be compromised, so it was important to find the cause of the reset and, if possible, to mitigate it. NASA assembled a team of engineers that included experts in radiation effects to tackle the problem. The first clue was the observation that the processor reset occurred during a solar event characterized by large increases in the proton and heavy ion fluxes emitted by the sun. To the radiation effects engineers on the team, this strongly suggested that particle radiation might be the culprit, particularly when it was discovered that the reset circuit contained three voltage comparators (LM139). Previous testing revealed that large voltage transients, or glitches appeared at the output of the LM139 when it was exposed to a beam of heavy ions [NI96]. The function of the reset circuit was to monitor the supply voltage and to issue a reset command to the processor should the voltage fall below a reference of 2.5 V [PO02]. Eventually, the team of engineers concluded that ionizing particle radiation from the solar event produced a negative voltage transient on the output of one of the LM139s sufficiently large to reset the processor on MAP. Fortunately, as of the end of 2004, only two such resets have occurred. The reset on MAP was not the first malfunction on a spacecraft attributed to a transient. That occurred shortly after the launch of NASA s TOPEX/Poseidon satellite in 1992. It was suspected, and later confirmed, that an anomaly in the Earth Sensor was caused by a transient in an operational amplifier (OP-15) [KO93]. Over the next few years, problems on TDRS, CASSINI, [PR02] SOHO [HA99,HA01] and TERRA were also attributed

  6. Lightcurve Based Classification Of Transients Events

    NASA Astrophysics Data System (ADS)

    Donalek, Ciro; Graham, M. J.; Mahabal, A.; Djorgovski, S. G.; Drake, A. J.; Moghaddam, B.; Turmon, M.; Chen, Y.; Sharma, N.

    2012-01-01

    In many scientific fields, a new generation of instruments is generating exponentially growing data streams, that may enable significant new discoveries. The requirement to perform the analysis rapidly and objectively, coupled with the huge amount of data available, implies a need for an automated event detection, classification, and decision making. In astronomy, this is the case with the new generation of synoptic sky surveys, that discover an ever increasing number of transient events. However, not all of them are equally interesting and worthy of a follow-up with limited resources. This presents some unusual classification challenges: the data are sparse, heterogeneous and incomplete; evolving in time; and most of the relevant information comes from a variety of archival data and contextual information. We are exploring a variety of machine learning techniques, using the ongoing CRTS sky survey as a testbed: Bayesian Network, [dm,dt] histograms, Decision Trees, Neural Networks, Symbolic Regression. In this work we focus on the lightcurve based classification using an hierarchical approach where some astrophysically motivated major features are used to separate different groups of classes. Proceeding down the classification hierarchy every node uses those classifiers that are demonstrated to work best for that particular task.

  7. Structure determination of transient transcription complexes.

    PubMed

    Cramer, Patrick

    2016-08-15

    The determination of detailed 3D structures of large and transient multicomponent complexes remains challenging. Here I describe the approaches that were used and developed by our laboratory to achieve structure solution of eukaryotic transcription complexes. I hope this collection serves as a resource for structural biologists seeking solutions for difficult structure determination projects. PMID:27528766

  8. A space-based radio frequency transient event classifier

    SciTech Connect

    Moore, K.R.; Blain, P.C.; Caffrey, M.P.; Franz, R.C.; Henneke, K.M.; Jones, R.G.

    1996-12-31

    The FORTE (Fast On-Orbit Recording of Transient Events) satellite will record RF transients in space. These transients will be classified onboard the spacecraft with an Event Classifier--specialized hardware that performs signal preprocessing and neural network classification. The authors describe the Event Classifier, future directions, and implications for telecommunications satellites. Telecommunication satellites are susceptible to damage from environmental factors such as deep dielectric charging and surface discharges. The event classifier technology the authors are developing is capable of sensing the surface discharges and could be useful for mitigating their effects. In addition, the techniques they are using for processing weak signals in noisy environments are relevant to telecommunications.

  9. A transient auroral event on the dayside

    SciTech Connect

    Heikkila, W.J. ); Jorgensen, T.S. ); Lanzerotti, L.J.; Maclennan, C.G. )

    1989-10-01

    On December 5, 1986, high-latitude magnetometer stations in Greenland, as well as Iqaluit and the South Pole, showed a strong perturbation lasting for about 10 min beginning at 0930 UT in an otherwise quiet period. A pair of field aligned currents separated in the east-west sense and moving westward (tailward) at 4--5 km/s is consistent with the data, producing a twin vortex pattern of Hall currents. Similar perturbations, but with reduced intensity, were also recorded on the afternoon side of Svalbard, Heiss Island, and several locations in northern Siberia. The perturbation was also observed with the incoherent scatter radar at Sondrestrom, these data agreeing with the twin vortex pattern. The perturbation was accompanied by auroral forms overhead at Sondrestrom that also traveled westward. Meridian scanning photometer recordings at the radar site showed the cleft, located about 3{degree} to 5{degree} poleward in latitude; the cleft did not move from the far northern sky for several hours, even while the disturbance was observed. Viking and Polar Bear satellites passed just before the disturbance over Greenland and DMSP encountered the disturbance near Baffin Island a few minutes later; these spacecraft observations increased our confidence in the interpretation of the data. ISEE 1/2 and IMP 8 recorded a magnetic disturbance in the solar wind, the likely cause of this event. Similar observations by others have been associated with flux transfer events. However, since the observed event occurred on closed field lines, our interpretation is quite different; it is that an impulsive penetration of solar wind plasma on an interplanetary magnetic flux tube took place through the magnetopause, ending up in the low latitude boundary layer. Some efficient mechanism is required to feed the boundary layer with the total amount observed. Other events reported in the literature may have a similar explanation.

  10. A transient auroral event on the dayside

    SciTech Connect

    Heikkila, W.J. ); Jorgensen, T.S. ); Lanzerotti, L.J.; Maclennan, C.G. )

    1989-11-01

    On December 5, 1986, high-latitude magnetometer stations in Greenland, as well as Iqaluit and the South Pole, showed a strong perturbation lasting for about 10 min beginning at 0930 UT in an otherwise quiet period. A pair of field aligned currents separated in the east-west sense and moving westward (tailward) at 4--5 km/s is consistent with the data, producing a twin vortex pattern of Hall currents. Similar perturbations, but with reduced intensity, were also recorded on the afternoon side at Svalbard, Heiss Island, and several locations in northern Siberia. The perturbation was also observed with the incoherent scatter radar at Sondrestrom, these data agreeing with the twin vortex pattern. The perturbation was accompanied by auroral forms overhead at Sondrestrom that also traveled westward. Meridian scanning photometer recordings at the radar site showed the cleft, located about 3{degree} to 5{degree} poleward in latitude; the cleft did not move from the far northern sky for several hours, even while the disturbance was observed. Viking and Polar Bear satellites passed just before the disturbance over Greenland and DMSP encountered the disturbance near Baffin Island a few minutes later; these spacecraft observations increased our confidence in the interpretation of the data. ISEE 1/2 and IMP 8 recorded a magnetic disturbance in the solar wind, the likely cause of this event. Similar observations by others have been associated with flux transfer events. However, since the observed event occurred on closed field lines, our interpretation is quite different; it is that an impulsive penetration of solar wind plasma on an interplanetary magnetic flux tube took place through the magnetopause, ending up in the low latitude boundary layer. Some efficient mechanism is required to feed the boundary layer with the total amount observed. Other events reported in the literature may have a similar explanation.

  11. Bounds on Transient Instability for Complex Ecosystems.

    PubMed

    Caravelli, Francesco; Staniczenko, Phillip P A

    2016-01-01

    Stability is a desirable property of complex ecosystems. If a community of interacting species is at a stable equilibrium point then it is able to withstand small perturbations to component species' abundances without suffering adverse effects. In ecology, the Jacobian matrix evaluated at an equilibrium point is known as the community matrix, which describes the population dynamics of interacting species. A system's asymptotic short- and long-term behaviour can be determined from eigenvalues derived from the community matrix. Here we use results from the theory of pseudospectra to describe intermediate, transient dynamics. We first recover the established result that the transition from stable to unstable dynamics includes a region of 'transient instability', where the effect of a small perturbation to species' abundances-to the population vector-is amplified before ultimately decaying. Then we show that the shift from stability to transient instability can be affected by uncertainty in, or small changes to, entries in the community matrix, and determine lower and upper bounds to the maximum amplitude of perturbations to the population vector. Of five different types of community matrix, we find that amplification is least severe when predator-prey interactions dominate. This analysis is relevant to other systems whose dynamics can be expressed in terms of the Jacobian matrix. PMID:27327511

  12. Bounds on Transient Instability for Complex Ecosystems

    PubMed Central

    2016-01-01

    Stability is a desirable property of complex ecosystems. If a community of interacting species is at a stable equilibrium point then it is able to withstand small perturbations to component species’ abundances without suffering adverse effects. In ecology, the Jacobian matrix evaluated at an equilibrium point is known as the community matrix, which describes the population dynamics of interacting species. A system’s asymptotic short- and long-term behaviour can be determined from eigenvalues derived from the community matrix. Here we use results from the theory of pseudospectra to describe intermediate, transient dynamics. We first recover the established result that the transition from stable to unstable dynamics includes a region of ‘transient instability’, where the effect of a small perturbation to species’ abundances—to the population vector—is amplified before ultimately decaying. Then we show that the shift from stability to transient instability can be affected by uncertainty in, or small changes to, entries in the community matrix, and determine lower and upper bounds to the maximum amplitude of perturbations to the population vector. Of five different types of community matrix, we find that amplification is least severe when predator-prey interactions dominate. This analysis is relevant to other systems whose dynamics can be expressed in terms of the Jacobian matrix. PMID:27327511

  13. Reevaluation of core damage frequency in light of the occurrence of complex transients at B and W plants

    SciTech Connect

    Youngblood, R.; Hsu, C.J.; Fitzpatrick, R.; Amico, P.

    1989-01-01

    This paper presents a unified treatment of ''complex transients'' and core damage events, with the aim of relating the frequencies if the two types of events to each other and to the frequencies of their constituent events. This framework provides a basis for relating the observed frequency of certain transient types to core damage frequency, and deciding whether the occurrence of complex transients means that core damage frequency is higher than it was previously believed to be. 5 refs.

  14. Conjugate observations of traveling convection vortices associated with transient events at the magnetopause

    NASA Astrophysics Data System (ADS)

    Kim, H.; Clauer, C. R.; Engebretson, M. J.; Matzka, J.; Sibeck, D. G.; Singer, H. J.; Stolle, C.; Weimer, D. R.; Xu, Z.

    2015-03-01

    Traveling convection vortices (TCVs) are generally produced by field-aligned currents (FACs) at high latitudes associated with transient changes of the magnetopause. This paper presents multipoint conjugate observations of transient events at the magnetopause measured in space and on the ground. The transient events showing radial fluctuation of the magnetopause in association with sudden increases in solar wind dynamic pressure were detected by both the Time History of Events and Macroscale Interactions during Substorms and the Geostationary Operational Environmental Satellite spacecraft. Geomagnetic signatures seen as TCVs in response to the transient events were observed by the ground magnetometer array in Greenland and Canada and their conjugate locations in Antarctica including recently developed Antarctic magnetometers, mostly located along the 40° magnetic meridian. This new conjugate network provides a unique opportunity to observe geomagnetic field signatures over a relatively large region in both hemispheres. This study focuses mainly on the spatial and temporal features of the TCVs in the conjugate hemispheres in relation to the transient events at the magnetopause. The TCV events are characterized by their single or twin vortex, of which the centers are located approximately at 72°-76° magnetic latitude, propagating either dawnward or duskward away from local noon. While interhemispheric conjugacy is expected with an assumption that TCV signatures are created by FACs directed in both hemispheres, our observations suggest that there might be more complex mechanisms contributing the asymmetrical features, perhaps due to field line mapping and/or conductivity differences.

  15. A space-based radio frequency transient event classifier

    SciTech Connect

    Moore, K.R.; Blain, C.P.; Caffrey, M.P.; Franz, R.C.; Henneke, K.M.; Jones, R.G.

    1998-03-01

    The Department of Energy is currently investigating economical and reliable techniques for space-based nuclear weapon treaty verification. Nuclear weapon detonations produce RF transients that are signatures of illegal nuclear weapons tests. However, there are many other sources of RF signals, both natural and man-made. Direct digitization of RF signals requires rates of 300 MSamples per second and produces 10{sup 13} samples per day of data to analyze. it is impractical to store and downlink all digitized RF data from such a satellite without a prohibitively expensive increase in the number and capacities of ground stations. Reliable and robust data processing and information extraction must be performed onboard the spacecraft in order to reduce downlinked data to a reasonable volume. The FORTE (Fast On-Orbit Recording of Transient Events) satellite records RF transients in space. These transients will be classified onboard the spacecraft with an Event Classifier specialized hardware that performs signal preprocessing and neural network classification. The authors describe the Event Classifier requirements, scientific constraints, design and implementation.

  16. An Android application for receiving notifications of astrophysical transient events

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Bond, I. A.; Sweatman, W. L.

    2014-10-01

    We describe an application written for the Android platform for receiving real-time notifications of astrophysical transient events. The key feature of our application is the use of message oriented middleware as a message broker, with the messages in VOEvent format. We describe the design features and implementation details of our application. In particular, it was necessary to implement support for the Simple Text Oriented Messaging Protocol (STOMP) to allow communication with the broker. Our application is designed around VOEvent alerts from the Microlensing Observations in Astrophysics (MOA) project, but could easily be adapted for other surveys that issue VOEvent notices of astrophysical transients.

  17. Analysis and RHBD technique of single event transients in PLLs

    NASA Astrophysics Data System (ADS)

    Zhiwei, Han; Liang, Wang; Suge, Yue; Bing, Han; Shougang, Du

    2015-11-01

    Single-event transient susceptibility of phase-locked loops has been investigated. The charge pump is the most sensitive component of the PLL to SET, and it is hard to mitigate this effect at the transistor level. A test circuit was designed on a 65 nm process using a new system-level radiation-hardening-by-design technique. Heavy-ion testing was used to evaluate the radiation hardness. Analyses and discussion of the feasibility of this method are also presented.

  18. Transient Events in Archival VLA Observations of the Galactic Center

    NASA Astrophysics Data System (ADS)

    Chiti, Anirudh; Chatterjee, S.; Wharton, R.; Cordes, J. M.; Lazio, J.; Kaplan, D. L.; Bower, G. C.; Croft, S.

    2014-01-01

    A number of different classes of stars, sub-stellar objects, and stellar remnants exhibit variability at radio wavelengths on time scales ranging from sub-seconds to hours. The direction toward the Galactic center not only has the highest stellar densities in the Galaxy, but also appears to have a range of interstellar scattering properties that may aid in the detection of new, radio-selected transient events. We have examined all archival VLA observations of the Galactic center field from 1985 to 2005 at 5 GHz and 8.4 GHz for a total of 214 hours of integration time, spanning 99 observations at 5 GHz with a typical area of 4.41E-4 square degrees and 116 observations at 8.4 GHz with a typical area of 8E-4 square degrees. We used a pipeline to search for transient events down to the shortest time scales allowed by the data (typically 10 seconds) by generating model-subtracted visibility data for each observation and then imaging the residual visibilities over short time intervals to search for outlier events. We present one radio transient event and at least 7 other promising candidates with significances ranging from 5.6 to 10.2 sigma that have passed all our tests, and discuss the possible source classes for these candidates and the event rate implications. We acknowledge support from the National Science Foundation for this work. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  19. Solar transient events and their importance for coronal heating.

    PubMed

    Doyle, J Gerry; Madjarska, Maria S

    2004-01-01

    Over the last decade, the uninterrupted high resolution coverage of the Sun both from the excellent range of telescopes aboard many spacecrafts and from ground-based instruments has led to a wealth of observations of small-scale dynamic events observed from the chromosphere to the transition region and corona. Since many of these events were observed with different instruments they show different properties from one another. It is suggested that many of these phenomena result from small-scale reconnection events due to the continually evolving magnetic fields as seen at the photospheric level, although waves are thought to play an important heating role as well. Nowadays, there is a general consensus that the key to understanding how the solar plasma is accelerated and heated may well be found in the study of these small-scale dynamic events. Here we give a brief review of the range of observed transient features and suggest that these small-scale events may well have broad implications for the mass and energy balance of the whole upper atmosphere of the Sun and the solar wind. PMID:15782773

  20. Event extraction with complex event classification using rich features.

    PubMed

    Miwa, Makoto; Saetre, Rune; Kim, Jin-Dong; Tsujii, Jun'ichi

    2010-02-01

    Biomedical Natural Language Processing (BioNLP) attempts to capture biomedical phenomena from texts by extracting relations between biomedical entities (i.e. proteins and genes). Traditionally, only binary relations have been extracted from large numbers of published papers. Recently, more complex relations (biomolecular events) have also been extracted. Such events may include several entities or other relations. To evaluate the performance of the text mining systems, several shared task challenges have been arranged for the BioNLP community. With a common and consistent task setting, the BioNLP'09 shared task evaluated complex biomolecular events such as binding and regulation.Finding these events automatically is important in order to improve biomedical event extraction systems. In the present paper, we propose an automatic event extraction system, which contains a model for complex events, by solving a classification problem with rich features. The main contributions of the present paper are: (1) the proposal of an effective bio-event detection method using machine learning, (2) provision of a high-performance event extraction system, and (3) the execution of a quantitative error analysis. The proposed complex (binding and regulation) event detector outperforms the best system from the BioNLP'09 shared task challenge. PMID:20183879

  1. Heavy Ion and Proton Induced Single Event Transients in Linear Devices

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Coss, J. R.; Miyahira, T.; Schwartz, H. R.

    1996-01-01

    This paper presents a display of heavy-ion and proton-induced single event transients for selected linear devices. The transient vital signs are serious; low LET threshold, high voltage amplitude and extended pulse duration (microsecs.).

  2. Event oriented dictionary learning for complex event detection.

    PubMed

    Yan, Yan; Yang, Yi; Meng, Deyu; Liu, Gaowen; Tong, Wei; Hauptmann, Alexander G; Sebe, Nicu

    2015-06-01

    Complex event detection is a retrieval task with the goal of finding videos of a particular event in a large-scale unconstrained Internet video archive, given example videos and text descriptions. Nowadays, different multimodal fusion schemes of low-level and high-level features are extensively investigated and evaluated for the complex event detection task. However, how to effectively select the high-level semantic meaningful concepts from a large pool to assist complex event detection is rarely studied in the literature. In this paper, we propose a novel strategy to automatically select semantic meaningful concepts for the event detection task based on both the events-kit text descriptions and the concepts high-level feature descriptions. Moreover, we introduce a novel event oriented dictionary representation based on the selected semantic concepts. Toward this goal, we leverage training images (frames) of selected concepts from the semantic indexing dataset with a pool of 346 concepts, into a novel supervised multitask lp -norm dictionary learning framework. Extensive experimental results on TRECVID multimedia event detection dataset demonstrate the efficacy of our proposed method. PMID:25794390

  3. Sensor Webs: Autonomous Rapid Response to Monitor Transient Science Events

    NASA Technical Reports Server (NTRS)

    Mandl, Dan; Grosvenor, Sandra; Frye, Stu; Sherwood, Robert; Chien, Steve; Davies, Ashley; Cichy, Ben; Ingram, Mary Ann; Langley, John; Miranda, Felix

    2005-01-01

    To better understand how physical phenomena, such as volcanic eruptions, evolve over time, multiple sensor observations over the duration of the event are required. Using sensor web approaches that integrate original detections by in-situ sensors and global-coverage, lower-resolution, on-orbit assets with automated rapid response observations from high resolution sensors, more observations of significant events can be made with increased temporal, spatial, and spectral resolution. This paper describes experiments using Earth Observing 1 (EO-1) along with other space and ground assets to implement progressive mission autonomy to identify, locate and image with high resolution instruments phenomena such as wildfires, volcanoes, floods and ice breakup. The software that plans, schedules and controls the various satellite assets are used to form ad hoc constellations which enable collaborative autonomous image collections triggered by transient phenomena. This software is both flight and ground based and works in concert to run all of the required assets cohesively and includes software that is model-based, artificial intelligence software.

  4. Controlling extreme events on complex networks

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Zhong; Huang, Zi-Gang; Lai, Ying-Cheng

    2014-08-01

    Extreme events, a type of collective behavior in complex networked dynamical systems, often can have catastrophic consequences. To develop effective strategies to control extreme events is of fundamental importance and practical interest. Utilizing transportation dynamics on complex networks as a prototypical setting, we find that making the network ``mobile'' can effectively suppress extreme events. A striking, resonance-like phenomenon is uncovered, where an optimal degree of mobility exists for which the probability of extreme events is minimized. We derive an analytic theory to understand the mechanism of control at a detailed and quantitative level, and validate the theory numerically. Implications of our finding to current areas such as cybersecurity are discussed.

  5. Global distributions and occurrence rates of transient luminous events

    NASA Astrophysics Data System (ADS)

    Chen, Alfred B.; Kuo, Cheng-Ling; Lee, Yi-Jen; Su, Han-Tzong; Hsu, Rue-Ron; Chern, Jyh-Long; Frey, Harald U.; Mende, Stephen B.; Takahashi, Yukihiro; Fukunishi, Hiroshi; Chang, Yeou-Shin; Liu, Tie-Yue; Lee, Lou-Chuang

    2008-08-01

    We report the global transient luminous event (TLE) distributions and rates based on the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) experiment onboard the FORMOSAT-2 satellite. ISUAL observations cover 45°S to 25°N latitude during the northern summer and 25°S to 45°N latitude during the northern winter. From July 2004 to June 2007, ISUAL recorded 5,434 elves, 633 sprites, 657 halos, and 13 gigantic jets. Surprisingly, elve is the dominant type of TLEs, while sprites/halos are a distant second. Elve occurrence rate jumps as the sea surface temperature exceeds 26 degrees Celsius, manifesting an ocean-atmosphere-ionosphere coupling. In the ISUAL survey, elves concentrate over the Caribbean Sea, South China Sea, east Indian Ocean, central Pacific Ocean, west Atlantic Ocean, and southwest Pacific Ocean; while sprites congregate over central Africa, Japan Sea, and west Atlantic Ocean. The ISUAL experiment observed global rates of 3.23, 0.50, 0.39, and 0.01 events per minute for elves, sprites, halos, and gigantic jets, respectively. Taking the instrumental detection sensitivity and the restricted survey area into account, the corrected global occurrence rates for sprites and elves likely are a factor of two and an order of magnitude higher, respectively. ISUAL observations also indicate that the relative frequency of high peak current lightning (>80 kA) is 10 times higher over the oceans than over the land. On the basis of the corrected ISUAL elve global occurrence rate, the total electron content at the lower ionosphere above elve hot zones was computed to be elevated by more than 5%.

  6. Production of Nitrogen Oxides by Laboratory Simulated Transient Luminous Events

    NASA Astrophysics Data System (ADS)

    Peterson, H.; Bailey, M.; Hallett, J.; Beasley, W.

    2007-12-01

    Restoration of the polar stratospheric ozone layer has occurred at rates below those originally expected following reductions in chlorofluorocarbon (CFC) usage. Additional reactions affecting ozone depletion now must also be considered. This research examines nitrogen oxides (NOx) produced in the middle atmosphere by transient luminous events (TLEs), with NOx production in this layer contributing to the loss of stratospheric ozone. In particular, NOx produced by sprites in the mesosphere would be transported to the polar stratosphere via the global meridional circulation and downward diffusion. A pressure-controlled vacuum chamber was used to simulate middle atmosphere pressures, while a power supply and in-chamber electrodes were used to simulate TLEs in the pressure controlled environment. Chemiluminescence NOx analyzers were used to sample NOx produced by the chamber discharges- originally a Monitor Labs Model 8440E, later a Thermo Environment Model 42. Total NOx production for each discharge as well as NOx per ampere of current and NOx per Joule of discharge energy were plotted. Absolute NOx production was greatest for discharge environments with upper tropospheric pressures (100-380 torr), while NOx/J was greatest for discharge environments with stratospheric pressures (around 10 torr). The different production efficiencies in NOx/J as a function of pressure pointed to three different production regimes, each with its own reaction mechanisms: one for tropospheric pressures, one for stratospheric pressures, and one for upper stratospheric to mesospheric pressures (no greater than 1 torr).

  7. Application of Pellet Injection to Mitigate Transient Events in ITER

    NASA Astrophysics Data System (ADS)

    Baylor, Larry

    2015-11-01

    The injection of cryogenic pellets has been shown to be useful for mitigation of ELMs and disruptions, which are potentially damaging transient events that can to lead to reduced operating time in ITER. The triggering of small ELMs by pellets has been demonstrated as a method to prevent large ELMs that can erode plasma facing components. D2 pellets <3mm in size are planned for ITER to trigger ELMs at higher rates than they will naturally occur. Injection of multiple large pellets >25mm in size of neon, argon, and D2 mixtures are planned to mitigate disruptions. Shattered pellets have been shown to successfully mitigate thermal and current quenches in DIII-D with higher assimilation than massive gas injection. A flexible multi-barrel system for shattered pellet injection is now being designed for disruption mitigation in ITER. The technology and the physics of the pellet plasma interactions for these systems on ITER will be discussed. This work supported by the Oak Ridge National Laboratory, managed by UT-Battelle, LLC for the US DOE under DE-AC05-00OR22725.

  8. Waves associated to COMPLEX EVENTS observed by STEREO

    NASA Astrophysics Data System (ADS)

    Siu Tapia, A. L.; Blanco-Cano, X.; Kajdic, P.; Aguilar-Rodriguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.

    2012-12-01

    Complex Events are formed by two or more large-scale solar wind structures which interact in space. Typical cases are interactions of: (i) a Magnetic Cloud/Interplanetary Coronal Mass Ejection (MC/ICME) with another MC/ICME transient; and (ii) an ICME followed by a Stream Interaction Region (SIR). Complex Events are of importance for space weather studies and studying them can enhance our understanding of collisionless plasma physics. Some of these structures can produce or enhance southward magnetic fields, a key factor in geomagnetic storm generation. Using data from the STEREO mission during the years 2006-2011, we found 17 Complex Events preceded by a shock wave. We use magnetic field and plasma data to study the micro-scale structure of the shocks, and the waves associated to these shocks and within Complex Events structures. To determine wave characteristics we perform Power Spectra and Minimum Variance Analysis. We also use PLASTIC WAP protons data to study foreshock extensions and the relationship between Complex Regions and particle acceleration to suprathermal energies.

  9. Magnetic Resonance Access to Transiently Formed Protein Complexes**

    PubMed Central

    Sára, Tomáš; Schwarz, Thomas C; Kurzbach, Dennis; Wunderlich, Christoph H; Kreutz, Christoph; Konrat, Robert

    2014-01-01

    Protein–protein interactions are of utmost importance to an understanding of biological phenomena since non-covalent and therefore reversible couplings between basic proteins leads to the formation of complex regulatory and adaptive molecular systems. Such systems are capable of maintaining their integrity and respond to external stimuli, processes intimately related to living organisms. These interactions, however, span a wide range of dissociation constants, from sub-nanomolar affinities in tight complexes to high-micromolar or even millimolar affinities in weak, transiently formed protein complexes. Herein, we demonstrate how novel NMR and EPR techniques can be used for the characterization of weak protein–protein (ligand) complexes. Applications to intrinsically disordered proteins and transiently formed protein complexes illustrate the potential of these novel techniques to study hitherto unobserved (and unobservable) higher-order structures of proteins. PMID:25050230

  10. Underlying mechanisms of transient luminous events: a review

    NASA Astrophysics Data System (ADS)

    Surkov, V. V.; Hayakawa, M.

    2012-08-01

    Transient luminous events (TLEs) occasionally observed above a strong thunderstorm system have been the subject of a great deal of research during recent years. The main goal of this review is to introduce readers to recent theories of electrodynamics processes associated with TLEs. We examine the simplest versions of these theories in order to make their physics as transparent as possible. The study is begun with the conventional mechanism for air breakdown at stratospheric and mesospheric altitudes. An electron impact ionization and dissociative attachment to neutrals are discussed. A streamer size and mobility of electrons as a function of altitude in the atmosphere are estimated on the basis of similarity law. An alternative mechanism of air breakdown, runaway electron mechanism, is discussed. In this section we focus on a runaway breakdown field, characteristic length to increase avalanche of runaway electrons and on the role played by fast seed electrons in generation of the runaway breakdown. An effect of thunderclouds charge distribution on initiation of blue jets and gigantic jets is examined. A model in which the blue jet is treated as upward-propagating positive leader with a streamer zone/corona on the top is discussed. Sprite models based on streamer-like mechanism of air breakdown in the presence of atmospheric conductivity are reviewed. To analyze conditions for sprite generation, thunderstorm electric field arising just after positive cloud-to-ground stroke is compared with the thresholds for propagation of positively/negatively charged streamers and with runway breakdown. Our own estimate of tendril's length at the bottom of sprite is obtained to demonstrate that the runaway breakdown can trigger the streamer formation. In conclusion we discuss physical mechanisms of VLF (very low frequency) and ELF (extremely low frequency) phenomena associated with sprites.

  11. Development of transient initiating event frequencies for use in probabilistic risk assessments

    SciTech Connect

    Mackowiak, D.P.; Gentillon, C.D.; Smith, K.L.

    1985-05-01

    Transient initiating event frequencies are an essential input to the analysis process of a nuclear power plant probabilistic risk assessment. These frequencies describe events causing or requiring scrams. This report documents an effort to validate and update from other sources a computer-based data file developed by the Electric Power Research Institute (EPRI) describing such events at 52 United States commercial nuclear power plants. Operating information from the United States Nuclear Regulatory Commission on 24 additional plants from their date of commercial operation has been combined with the EPRI data, and the entire data base has been updated to add 1980 through 1983 events for all 76 plants. The validity of the EPRI data and data analysis methodology and the adequacy of the EPRI transient categories are examined. New transient initiating event frequencies are derived from the expanded data base using the EPRI transient categories and data display methods. Upper bounds for these frequencies are also provided. Additional analyses explore changes in the dominant transients, changes in transient outage times and their impact on plant operation, and the effects of power level and scheduled scrams on transient event frequencies. A more rigorous data analysis methodology is developed to encourage further refinement of the transient initiating event frequencies derived herein. Updating the transient event data base resulted in approx.2400 events being added to EPRI's approx.3000-event data file. The resulting frequency estimates were in most cases lower than those reported by EPRI, but no significant order-of-magnitude changes were noted. The average number of transients per year for the combined data base is 8.5 for pressurized water reactors and 7.4 for boiling water reactors.

  12. Controlling extreme events on complex networks

    PubMed Central

    Chen, Yu-Zhong; Huang, Zi-Gang; Lai, Ying-Cheng

    2014-01-01

    Extreme events, a type of collective behavior in complex networked dynamical systems, often can have catastrophic consequences. To develop effective strategies to control extreme events is of fundamental importance and practical interest. Utilizing transportation dynamics on complex networks as a prototypical setting, we find that making the network “mobile” can effectively suppress extreme events. A striking, resonance-like phenomenon is uncovered, where an optimal degree of mobility exists for which the probability of extreme events is minimized. We derive an analytic theory to understand the mechanism of control at a detailed and quantitative level, and validate the theory numerically. Implications of our finding to current areas such as cybersecurity are discussed. PMID:25131344

  13. Controlling extreme events on complex networks.

    PubMed

    Chen, Yu-Zhong; Huang, Zi-Gang; Lai, Ying-Cheng

    2014-01-01

    Extreme events, a type of collective behavior in complex networked dynamical systems, often can have catastrophic consequences. To develop effective strategies to control extreme events is of fundamental importance and practical interest. Utilizing transportation dynamics on complex networks as a prototypical setting, we find that making the network "mobile" can effectively suppress extreme events. A striking, resonance-like phenomenon is uncovered, where an optimal degree of mobility exists for which the probability of extreme events is minimized. We derive an analytic theory to understand the mechanism of control at a detailed and quantitative level, and validate the theory numerically. Implications of our finding to current areas such as cybersecurity are discussed. PMID:25131344

  14. Applying Machine Learning Tools to the Identification of Foreshock Transient Events

    NASA Astrophysics Data System (ADS)

    Beyene, F.; Murr, D.

    2015-12-01

    Our previous research attempted to establish the relationship between foreshock transient events and transients in the ionosphere observed with ground magnetometers. This earlier work relied on foreshock transient event lists that were generated by a visual survey of the THEMIS data near the bowshock/foreshock. Our aim is to extend our earlier work, and the overall understanding of foreshock transients, by employing machine learning tools to identify foreshock transient events. Successful application of these tools would allow use to survey much more data. We first present results of automated classification of THEMIS data into the three primary regions of solar wind, magnetosheath, and magnetosphere. We then present our initial results of training an SVM classifier using the human generated event list and applying it to a more extensive data set.

  15. Transient luminous events above two mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Lang, Timothy; Rutledge, Steve; Lyons, Walt; Cummer, Steve; Li, Jingbo; Macgorman, Don

    2010-05-01

    Two warm-season mesoscale convective systems (MCSs) were analyzed with respect to production of transient luminous events (TLEs), mainly sprites. Sprites were documented over the lightning mapping array (LMA) network in Oklahoma, USA, using highly sensitive optical cameras operated at Yucca Ridge in Ft. Collins, Colorado, as part of our Sprites 2007 field campaign. Information about charge moment changes in lightning flashes was obtained by the National Charge Moment Change Network (CMCN). Cloud-to-ground lightning data were obtained from the National Lightning Detection Network (NLDN). The 20 June 2007 symmetric MCS produced 282 observed TLEs over a 4-h period, during which time the storm's intense convection weakened and its stratiform region strengthened. In contrast to previous sprite studies, the stratiform charge layer involved in producing the TLE-parent positive cloud-to-ground (+CG) lightning flash was situated at upper levels as opposed to near the melting level. This layer was physically connected to an even higher upper-level convective positive charge region via a downward-sloping pathway. The average altitude discharged by TLE-parent flashes during TLE activity was 8.2 km above mean sea level (MSL; -25 °C). The 9 May 2007 asymmetric MCS produced 25 observed TLEs over a 2-h period, during which the storm's convection rapidly weakened before recovering later. The 9 May storm best fit the conventional model of low-altitude positive charge playing the dominant role in sprite production; however, the average altitude discharged during the TLE phase of flashes still was higher than the melting level: 6.1 km MSL (-15 °C). The average TLE-parent +CG flash in the symmetric 20 June case initiated at higher altitude, discharged a substantially larger area, had a larger peak current, and tapped positive charge at higher altitude compared to the asymmetric 9 May case. Analysis of full charge moment change (CMC) data from TLE-parent +CGs in these two cases

  16. On transient events in the upper atmosphere generated away of thunderstorm regions

    NASA Astrophysics Data System (ADS)

    Morozenko, V.; Garipov, G.; Khrenov, B.; Klimov, P.; Panasyuk, M.; Sharakin, S.; Zotov, M.

    2011-12-01

    Experimental data on transient events in UV and Red-IR ranges obtained in the MSU missions "Unversitetsky-Tatiana" (wavelengths 300-400 nm) and "Unversitetsky-Tatiana-2" (wavelengths 300-400 nm and 600-800 nm), published by Garipov et al, in 2010 at COSPAR session http://www.cospar2010.org, at TEPA conference http://www.aragats.am/Conferences/tepa2010 and in 2011 by Sadovnichy et al, Solar System Research, 45, #1, 3-29 (2011); Vedenkin et al, JETP, v. 140, issue 3(9), 1-11 (2011) demonstrated existence of transients at large distances (up to thousands km) away of cloud thunderstorm regions. Those "remote" transients are short (1-5 msec) and are less luminous than the transients above thunderstorm regions. The ratio of Red-IR to UV photon numbers in those transients indicates high altitude of their origin (~70 km). Important observation facts are also: 1. a change of the exponent in transient distribution on luminosity Q ("-1" for photon numbers Q=1020 -1023 to "-2" for Q>1023), 2. a change of global distribution of transient with their luminosity (transients with Q>1023 are concentrated in equatorial range above continents, while transients with low luminosity are distributed more uniformly), 3. a phenomenon of transient sequences in one satellite orbit which is close to geomagnetic meridian. In the present paper phenomenological features of transients are explained in assumption that the observed transients have to be divided in two classes: 1. transients related to local, lower in the atmosphere, lightning at distance not more than hundreds km from satellite detector field of view in the atmosphere and 2. transients generated by far away lightning. Local transients are luminous and presumably are events called "transient luminous events" (TLE). In distribution on luminosity those events have some threshold Q~1023 and their differential luminosity distribution is approximated by power law exponent "-2". Remote transients have to be considered separately. Their

  17. Using GPS to Rapidly Detect and Model Earthquakes and Transient Deformation Events

    NASA Astrophysics Data System (ADS)

    Crowell, Brendan W.

    The rapid modeling and detection of earthquakes and transient deformation is a problem of extreme societal importance for earthquake early warning and rapid hazard response. To date, GPS data is not used in earthquake early warning or rapid source modeling even in Japan or California where the most extensive geophysical networks exist. This dissertation focuses on creating algorithms for automated modeling of earthquakes and transient slip events using GPS data in the western United States and Japan. First, I focus on the creation and use of high-rate GPS and combined seismogeodetic data for applications in earthquake early warning and rapid slip inversions. Leveraging data from earthquakes in Japan and southern California, I demonstrate that an accurate magnitude estimate can be made within seconds using P wave displacement scaling, and that a heterogeneous static slip model can be generated within 2-3 minutes. The preliminary source characterization is sufficiently robust to independently confirm the extent of fault slip used for rapid assessment of strong ground motions and improved tsunami warning in subduction zone environments. Secondly, I investigate the automated detection of transient slow slip events in Cascadia using daily positional estimates from GPS. Proper geodetic characterization of transient deformation is necessary for studies of regional interseismic, coseismic and postseismic tectonics, and miscalculations can affect our understanding of the regional stress field. I utilize the relative strength index (RSI) from financial forecasting to create a complete record of slow slip from continuous GPS stations in the Cascadia subduction zone between 1996 and 2012. I create a complete history of slow slip across the Cascadia subduction zone, fully characterizing the timing, progression, and magnitude of events. Finally, using a combination of continuous and campaign GPS measurements, I characterize the amount of extension, shear and subsidence in the

  18. THEMIS Observations of Unusual Bow Shock Motion, Attending a Transient Magnetospheric Event

    NASA Technical Reports Server (NTRS)

    Korotova, Galina; Sibeck, David; Omidi, N.; Angelopoulos, V.

    2013-01-01

    We present a multipoint case study of solar wind and magnetospheric observations during a transient magnetospheric compression at 2319 UT on October 15, 2008. We use high-time resolution magnetic field and plasma data from the THEMIS and GOES-11/12 spacecraft to show that this transient event corresponded to an abrupt rotation in the IMF orientation, a change in the location of the foreshock, and transient outward bow shock motion. We employ results from a global hybrid code model to reconcile the observations indicating transient inward magnetopause motion with the outward bow shock motion.

  19. A very long-term transient event preceding the 2011 Tohoku earthquake.

    PubMed

    Yokota, Yusuke; Koketsu, Kazuki

    2015-01-01

    Geodetic transients have been observed in various subduction zones. The 2011 Tohoku earthquake occurred in one of the most active subduction zones globally, the Japan Trench subduction zone (JTSZ). However, no geodetic transient (except afterslip and so on) had been reported in the JTSZ before the Tohoku earthquake. Here we show that a large transient event, with duration longer than any reported previously, occurred in the JTSZ preceding the Tohoku earthquake. We calculate tectonic deformations at Global Positioning System stations along the JTSZ by removing the effects of nearby M(w) 6-8 earthquakes. We identify temporal changes in these deformations, deriving 9-year deviation records from regular deformations due to slip deficit at the plate boundary. We perform an inversion of the deviations to obtain the source model of their root event. The relationship between the obtained transient event and Tohoku earthquake is shown through Coulomb stress change and seismic supercycle simulation. PMID:25562609

  20. Transient events at the magnetopause and bipolar magnetic signatures

    NASA Astrophysics Data System (ADS)

    Kruparova, O.; Šafránková, J.; Němeček, Z.; Přech, L.

    2015-09-01

    Bipolar signatures in the magnetic field component perpendicular to a nominal magnetopause surface accompanied with an increase of the magnetic field strength are regularly attributed to flux transfer events (FTEs) crossing the spacecraft. The detailed analysis of one such event shows that the magnetic signatures are consistent with the FTE but the timing of multipoint observations and the interpretation of changes of plasma parameters in terms of FTEs requires additional assumptions. We argue that although the event exhibits clear FTE signatures, an explanation of the observations as a local magnetopause surface deformation associated with a change of the magnetosheath density better fits to the data. The deformation caused by this density depression at the magnetopause is associated with a rotation of the magnetosheath magnetic field.

  1. Toward an Intelligent Event Broker: Automated Transient Classificaiton

    NASA Astrophysics Data System (ADS)

    Wozniak, P.

    In order to succeed, the massive time-domain surveys of the future must automatically identify actionable information from the torrent of imaging data, classify emerging events, and optimize the follow-up strategy. To address this challenge, we are developing a fully autonomous, distributed event broker that will integrate cutting edge machine learning algorithms with high performance computing infrastructure. The talk will give an overview of this work and recent progress on image level variability detection and spectral classification using low resolution spectra.

  2. A transient digitiser for fast air shower events

    NASA Technical Reports Server (NTRS)

    Wild, N. R.; Clay, R. W.

    1985-01-01

    Air shower structure are often measured on time scales of a few nanoseconds. Longitudinal disk structure near the core is of the order of meters in dimension, air Cerenkov pulses have full widths at half maximum of the order of tens of nanoseconds, and fast timing over typical arrays is usually measured to nanosecond accuracy. oscilloscopes can be used but have very limited dynamic range and are expensive if measurements down to a few nanoseconds are to be made. For the fast Cerenkov work, an instrument with better dynamic range than an oscilloscope and with a time resolution sufficient to allow measurements limited only by system risetime of a few nanoseconds is needed. A 16/32 channel, 8 bit, fast transient digitizer was designed and built which runs at sample intervals down to approx. 1 nanosecond per channel.

  3. Biomagnetic localization from transient quasi-static events

    SciTech Connect

    Mosher, J.C.; Leahy, R.M.; Lewis, P.S. University of Southern California, Los Angeles, CA . Signal and Image Processing Inst.)

    1993-01-01

    Sensory stimuli, such as auditory, visual, or somatosensory, evoke neural responses in very localized regions of the brain. A SQUID biomagnetometer can measure the very weak fields that are generated outside of the head by this response. A simple source and head model of current dipoles inside a conducting sphere is typically used to interpret these magnetic field measurements or magnetoencephalogram (MEG). Locating dipole sources using data recorded from an array of biomagnetic sensors is distinguished from conventional array source localization techniques by the quasi-static transient nature of the data. Here, the basic MEG model is reviewed, then a localization example is given to motivate the need for partitioning the data to improve estimator performance. Tune-eigenspectrum analysis is introduced as a means of partitioning and interpreting spatio-temporal biomagnetic data. Examples using both simulated and somatosensory data are presented.

  4. Biomagnetic localization from transient quasi-static events

    SciTech Connect

    Mosher, J.C.; Leahy, R.M.; Lewis, P.S. |

    1993-02-01

    Sensory stimuli, such as auditory, visual, or somatosensory, evoke neural responses in very localized regions of the brain. A SQUID biomagnetometer can measure the very weak fields that are generated outside of the head by this response. A simple source and head model of current dipoles inside a conducting sphere is typically used to interpret these magnetic field measurements or magnetoencephalogram (MEG). Locating dipole sources using data recorded from an array of biomagnetic sensors is distinguished from conventional array source localization techniques by the quasi-static transient nature of the data. Here, the basic MEG model is reviewed, then a localization example is given to motivate the need for partitioning the data to improve estimator performance. Tune-eigenspectrum analysis is introduced as a means of partitioning and interpreting spatio-temporal biomagnetic data. Examples using both simulated and somatosensory data are presented.

  5. Peculiar transient events in the Schumann resonance band and their possible explanation

    NASA Astrophysics Data System (ADS)

    Ondrásková, Adriena; Bór, József; S[Breve]Evcík, Sebastián; Kostecký, Pavel; Rosenberg, Ladislav

    2008-04-01

    Superimposed on the continuous Schumann resonance (SR) background in the extremely low frequency (ELF) band, transient signals (e.g. bursts) can be observed, which originate from intense lightning discharges occurring at different locations on the globe. From the many transients that were observed at the Astronomical and Geophysical Observatory (AGO) of Comenius University near Modra, western Slovakia, in the vertical electric field component mainly during May and June of 2006, a peculiar group of events could be recognized. According to the waveform analysis, these peculiar events in most cases consist of two overlapping transients with a characteristic time difference of 0.13-0.15 s between the onsets. On the other hand, the spectrum of these peculiar transients showed discernible SR peaks for higher modes as well (n>7). The same events could be found in the records of the Széchenyi István Geophysical Observatory of the Geodetic and Geophysical Research Institute of the Hungarian Academy of Sciences near Nagycenk, Hungary (NCK). The natural origin of the peculiar events was verified from the NCK data and the source location was determined from the second transient. The results suggest that the two consecutive transients originated in the same thunderstorm. Furthermore, the phase spectrum analysis indicates that the sources have coherently excited the Earth-ionosphere cavity. These findings seem to support the idea that electromagnetic waves orbiting the Earth might trigger lightning discharges. The possibility that electromagnetic waves may trigger discharges was first considered by Nikola Tesla.

  6. First Light with the NRAO Transient Event Capture Hardware

    NASA Astrophysics Data System (ADS)

    Langston, Glen; Rumberg, B.; Brandt, P.

    2007-12-01

    The design, implementation and testing of the first NRAO Event Capture data acquisition system is presented. The NRAO in Green Bank is developing a set of new data acquisition systems based on the U.C. Berkeley CASPER IBOB/ADC/BEE2 hardware. We describe the hardware configuration and initial experiences with the development system. We present first astronomical tests of the Event Capture system, using the 43m telescope (140ft). These observations were carried out at 900 MHz. The observations were made on 2007 July 8 and 9 towards the Crab pulsar, the galactic center, the Moon and two test observations while the 43m was pointed at Zenith (straight up). The Event Capture is one of several on-going FPGA based data acquisition projects being implemented for the Robert C. Byrd Green Bank Telescope (GBT) and for the 43m telescopes. The NRAO Configurable Instrument Collaboration for Agile Data Acquisition (CICADA) program is described at: http://wikio.nrao.edu/bin/view/CICADA

  7. Preliminary report on the CTS transient event counter performance through the 1976 spring eclipse season

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.; Lovell, R. R.; Klinect, V. W.

    1977-01-01

    The transient event counter is described, defining its operational characteristics, and presenting the preliminary results obtained through the first 90 days of operation including the Spring 1976 eclipse season. The results show that the CTS was charged to the point where discharges have occurred. The discharge induced transients have not caused any anomalous events in spacecraft operation. The data indicate that discharges can occur at any time during the day without preference to any local time quadrant. The number of discharges occurring in the 1 sec sample interval are greater than anticipated.

  8. Application of linker technique to trap transiently interacting protein complexes for structural studies

    PubMed Central

    Reddy Chichili, Vishnu Priyanka; Kumar, Veerendra; Sivaraman, J.

    2016-01-01

    Protein-protein interactions are key events controlling several biological processes. We have developed and employed a method to trap transiently interacting protein complexes for structural studies using glycine-rich linkers to fuse interacting partners, one of which is unstructured. Initial steps involve isothermal titration calorimetry to identify the minimum binding region of the unstructured protein in its interaction with its stable binding partner. This is followed by computational analysis to identify the approximate site of the interaction and to design an appropriate linker length. Subsequently, fused constructs are generated and characterized using size exclusion chromatography and dynamic light scattering experiments. The structure of the chimeric protein is then solved by crystallization, and validated both in vitro and in vivo by substituting key interacting residues of the full length, unlinked proteins with alanine. This protocol offers the opportunity to study crucial and currently unattainable transient protein interactions involved in various biological processes. PMID:26985443

  9. Multi-wavelength Observations of a Subarcsecond Penumbral Transient Brightening Event

    NASA Astrophysics Data System (ADS)

    Bai, X. Y.; Su, J. T.; Cao, W. D.; Liu, S. Q.; Deng, Y. Y.; Priya, T. G.

    2016-05-01

    We report a subarcsecond penumbral transient brightening event with the high-spatial resolution observations from the 1.6 m New Solar Telescope (NST), Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamics Observatory. The transient brightening, whose thermal energy is in the range of nanoflares, has signatures in the chromosphere, the transient region, and the corona. NST's Hα channel reveals the fine structure of the event with a width as narrow as 101 km (0.″14), which is much smaller than the width from the previous observation. The transient brightening lasts for about 3 minutes. It is associated with a redshift of about 17 km s‑1, found in the Si iv 1402.77 Å line and exhibits an inward motion to the umbra with a speed of 87 km s‑1. The small-scale energy released from the event has a multi-temperature component. Spectral analysis of the brightening region from IRIS shows that not only the transition region lines such as Si iv 1402.77 Å and C ii 1334.53 Å, but also the chromospheric Mg ii k 2796.35 Å line are significantly enhanced and broadened. In addition, the event can be found in all the extreme-ultraviolet passbands of the Atmospheric Imaging Assembly and the derived differential emission measure profile increases between 4 and 15 MK (or 6.6 ≤ log T ≤ 7.2) in the transient brightening phase. It is possible that the penumbral transient brightening event is caused by magnetic reconnection.

  10. Modeling and analysis of single-event transients in charge pumps

    NASA Astrophysics Data System (ADS)

    Zhenyu, Zhao; Junfeng, Li; Minxuan, Zhang; Shaoqing, Li

    2009-05-01

    It has been shown that charge pumps (CPs) dominate single-event transient (SET) responses of phase-locked loops (PLLs). Using a pulse to represent a single event hit on CPs, the SET analysis model is established and the characteristics of SET generation and propagation in PLLs are revealed. An analysis of single event transients in PLLs demonstrates that the settling time of the voltage-controlled oscillators (VCOs) control voltage after a single event strike is strongly dependent on the peak control voltage deviation, the SET pulse width, and the settling time constant. And the peak control voltage disturbance decreases with the SET strength or the filter resistance. Furthermore, the analysis in the proposed PLL model is confirmed by simulation results using MATLAB and HSPICE, respectively.

  11. Earth Crossing Asteroid Characterization by Transient Tidal Events

    NASA Astrophysics Data System (ADS)

    Movshovitz, N.; Asphaug, E. I.

    2011-12-01

    Most, if not all asteroids larger than a few hundred meters in diameter are rubble-piles - aggregates of small fragments, held together by self-gravity with virtually no tensile strength. These strenghless bodies are, ironically, very resistant to disruption by collisions, as density discontinuities in their interiors make it impossible for a shock front to propagate far from the impact point. Rubble-piles are, however, very susceptible to disruption by tidal forces. An Earth-Crossing asteroid (ECA) will experience a strong tidal force for a relatively short time, when its orbit brings it deep enough in the Earth's gravitational field. Before there is an asteroid collision with the Earth, we are likely to observe a number of tidal collisions - that is, events which cause observable changes to the asteroid. In addition, new high-resolution maps of the Moon by HiRISE record clear imprints of tidally disrupted asteroids (V. Bray, pers. comm.) So there are and will be data whereby we can understand the bulk asteroid geophysical properties that are so notoriously difficult (and expensive) to measure. Analytical expressions exist for the minimum circular orbit at which a fluid body can retain an equilibrium shape; this is the classic Roche limit. Similar expressions exist for ideal parabolic encounters by non-rotating liquid spheres (Sridhar and Tremaine, 1992). But a rubble-pile ECA will not behave like a fluid body; inter-particle forces and dilatation can prevent it from deforming. Every asteroid tidal encounter with the Earth is unique, so we need good models with the best physics, capable of exploring a wide parameter space. Richardson et al. (1998) explored the sensitivity of tidal disruption of Earth-crossing rubble-piles to the orbit periapse, encounter velocity, spin period, and deviation from sphericity; and found all four highly important in determining the extent of disruption of the progenitor body. They used an N-body code with energy dissipating collisions

  12. Limits on the Event Rates of Fast Radio Transients from the V-FASTR Experiment

    NASA Astrophysics Data System (ADS)

    Wayth, Randall B.; Tingay, Steven J.; Deller, Adam T.; Brisken, Walter F.; Thompson, David R.; Wagstaff, Kiri L.; Majid, Walid A.

    2012-07-01

    We present the first results from the V-FASTR experiment, a commensal search for fast transient radio bursts using the Very Long Baseline Array (VLBA). V-FASTR is unique in that the widely spaced VLBA antennas provide a discriminant against non-astronomical signals and a mechanism for the localization and identification of events that is not possible with single dishes or short baseline interferometers. Thus, far V-FASTR has accumulated over 1300 hr of observation time with the VLBA, between 90 cm and 3 mm wavelength (327 MHz-86 GHz), providing the first limits on fast transient event rates at high radio frequencies (>1.4 GHz). V-FASTR has blindly detected bright individual pulses from seven known pulsars but has not detected any single-pulse events that would indicate high-redshift impulsive bursts of radio emission. At 1.4 GHz, V-FASTR puts limits on fast transient event rates comparable with the PALFA survey at the Arecibo telescope, but generally at lower sensitivities, and comparable to the "fly's eye" survey at the Allen Telescope Array, but with less sky coverage. We also illustrate the likely performance of the Phase 1 SKA dish array for an incoherent fast transient search fashioned on V-FASTR.

  13. LIMITS ON THE EVENT RATES OF FAST RADIO TRANSIENTS FROM THE V-FASTR EXPERIMENT

    SciTech Connect

    Wayth, Randall B.; Tingay, Steven J.; Deller, Adam T.; Brisken, Walter F.; Thompson, David R.; Wagstaff, Kiri L.; Majid, Walid A.

    2012-07-10

    We present the first results from the V-FASTR experiment, a commensal search for fast transient radio bursts using the Very Long Baseline Array (VLBA). V-FASTR is unique in that the widely spaced VLBA antennas provide a discriminant against non-astronomical signals and a mechanism for the localization and identification of events that is not possible with single dishes or short baseline interferometers. Thus, far V-FASTR has accumulated over 1300 hr of observation time with the VLBA, between 90 cm and 3 mm wavelength (327 MHz-86 GHz), providing the first limits on fast transient event rates at high radio frequencies (>1.4 GHz). V-FASTR has blindly detected bright individual pulses from seven known pulsars but has not detected any single-pulse events that would indicate high-redshift impulsive bursts of radio emission. At 1.4 GHz, V-FASTR puts limits on fast transient event rates comparable with the PALFA survey at the Arecibo telescope, but generally at lower sensitivities, and comparable to the 'fly's eye' survey at the Allen Telescope Array, but with less sky coverage. We also illustrate the likely performance of the Phase 1 SKA dish array for an incoherent fast transient search fashioned on V-FASTR.

  14. Extra-galactic high-energy transients: event rate density and luminosity function

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Li, Zhuo

    2015-08-01

    Several types of extra-galactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with a relativistic jet. In this paper, we apply a unified method to systematically study the reshift-dependent event rate densities and luminosity functions of these extra-galactic high-energy transients. We consider star formation history as the tracer of the redshift distribution for long GRBs and SBOs. For short GRBs, we consider the compact star merger model to introduce several possible merger delay time distribution models. For TDEs, we consider the mass distribution of supermassive black holes as a function of redshift. We derive some empirical formulae for the redshift-dependent event rate density for different types of transients. Based on the observed events, we derive the local specific event rate density, ρ0,L ∝ dρ0/dL for each type of transient, which represents its luminosity function. All the transients are consistent with having a single power law luminosity function, except the high luminosity long GRBs (HL-lGRBs), whose luminosity function can be well described by a broken power law. The total event rate density for a particular transient depends on the luminosity threshold, and we obtain the following values in units of Gpc-3 yr-1: 2.82^{+0.41}_{-0.36} for HL-lGRBs above 4×1049 erg s-1 218^{+130}_{-86} for low luminosity long GRBs above 6×1046 erg s-1 3.18^{+0.88}_{-0.70}, 2.87^{+0.80}_{-0.64}, and 6.25^{+1.73}_{-1.38} above 5×1049 erg s-1 for short GRBs with three different merger delay models (Gaussian, log-normal, and power law); 2.0^{+2.6}_{-1.3}×104 above 9×1043 erg s-1 for SBOs, 3.0^{+1.0}_{-0.8}×105 for normal TDEs above 1042 erg s-1 and 6.2^{+8.2}_{-4.0} above 3×1047 erg s-1for TDE jets as discovered by Swift. Intriguingly, the global specific event rate densities

  15. Extragalactic High-energy Transients: Event Rate Densities and Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Li, Zhuo

    2015-10-01

    Several types of extragalactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with an associated relativistic jet. In this paper, we apply a unified method to systematically study the redshift-dependent event rate densities and the global luminosity functions (GLFs; ignoring redshift evolution) of these transients. We introduce some empirical formulae for the redshift-dependent event rate densities for different types of transients and derive the local specific event rate density, which also represents its GLF. Long GRBs (LGRBs) have a large enough sample to reveal features in the GLF, which is best charaterized as a triple power law (PL). All the other transients are consistent with having a single-power-law (SPL) LF. The total event rate density depends on the minimum luminosity, and we obtain the following values in units of Gpc-3 yr-1: {0.8}-0.1+0.1 for high-luminosity LGRBs above 1050 erg s-1 {164}-65+98 for low-luminosity LGRBs above 5 × 1046 erg s-1 {1.3}-0.3+0.4, {1.2}-0.3+0.4, and {3.3}-0.8+1.0 above 1050 erg s-1 for short GRBs with three different merger delay models (Gaussian, lognormal, and PL); {1.9}-1.2+2.4× {10}4 above 1044 erg s-1 for SBOs, {4.8}-2.1+3.2× {10}2 for normal TDEs above 1044 erg s-1 and {0.03}-0.02+0.04 above 1048 erg s-1 for TDE jets as discovered by Swift. Intriguingly, the GLFs of different kinds of transients, which cover over 12 orders of magnitude, are consistent with an SPL with an index of -1.6.

  16. Extragalactic High-energy Transients: Event Rate Densities and Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Li, Zhuo

    2015-10-01

    Several types of extragalactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with an associated relativistic jet. In this paper, we apply a unified method to systematically study the redshift-dependent event rate densities and the global luminosity functions (GLFs; ignoring redshift evolution) of these transients. We introduce some empirical formulae for the redshift-dependent event rate densities for different types of transients and derive the local specific event rate density, which also represents its GLF. Long GRBs (LGRBs) have a large enough sample to reveal features in the GLF, which is best charaterized as a triple power law (PL). All the other transients are consistent with having a single-power-law (SPL) LF. The total event rate density depends on the minimum luminosity, and we obtain the following values in units of Gpc‑3 yr‑1: {0.8}-0.1+0.1 for high-luminosity LGRBs above 1050 erg s‑1 {164}-65+98 for low-luminosity LGRBs above 5 × 1046 erg s‑1 {1.3}-0.3+0.4, {1.2}-0.3+0.4, and {3.3}-0.8+1.0 above 1050 erg s‑1 for short GRBs with three different merger delay models (Gaussian, lognormal, and PL); {1.9}-1.2+2.4× {10}4 above 1044 erg s‑1 for SBOs, {4.8}-2.1+3.2× {10}2 for normal TDEs above 1044 erg s‑1 and {0.03}-0.02+0.04 above 1048 erg s‑1 for TDE jets as discovered by Swift. Intriguingly, the GLFs of different kinds of transients, which cover over 12 orders of magnitude, are consistent with an SPL with an index of ‑1.6.

  17. A study of the equatorial signatures of long period transient events (600 - 7200 s)

    NASA Astrophysics Data System (ADS)

    Santos, J.; Dutra, S.; Trivedi, N.; Vieira, L.; Echer, E.; Schuch, N.

    Transient variations in the H magnetic field component of magnetograms at high latitude are a common feature. They are associated with energy transference from solar wind to the magnetosphere. Abrupt changes in the solar wind generate Alfvén and fast mode waves through the magnetosphere. The Alfvén wave doesn't propagate in the direction perpendicular to the geomagnetic field, so equatorial signatures are probably caused by fast mode waves. On the other hand, complicated signatures observed at high latitudes represent a composition of Alfvén and fast mode waves. A second suggested propagation mechanism to low latitudes is the Earth-ionosphere wave-guide. In this work, geomagnetic data from the Brazilian magnetic stations at Belém (BLM), Eusébio (EUS), Ji-Paraná (JIP), São luis (SLZ) and São Martinho da Serra (SMS), all located near the geomagnetic equator, are used to look for equatorial signatures of transient events with periods of 600 - 7200s. This period range includes two special types of transient variations named Traveling convection vortices (TCV) and DP2 fluctuations. We try to identify their morphological characteristics and compare with the high latitude phenomena's characteristics. Satellite data (WIND, ACE and GOES) are used to see magnetosphere signatures and solar wind and interplanetary magnetic field (IMF) conditions during the events. The main objective is try to find the contribution of each propagation mechanism of these transient events arriving at the equatorial latitudes.

  18. An analog cell to detect single event transients in voltage references

    NASA Astrophysics Data System (ADS)

    Franco, F. J.; Palomar, C.; Izquierdo, J. G.; Agapito, J. A.

    2015-01-01

    A reliable voltage reference is mandatory in mixed-signal systems. However, this family of components can undergo very long single event transients when operating in radiation environments such as space and nuclear facilities due to the impact of heavy ions. The purpose of the present paper is to demonstrate how a simple cell can be used to detect these transients. The cell was implemented with typical COTS components and its behavior was verified by SPICE simulations and in a laser facility. Different applications of the cell are explored as well.

  19. Method and apparatus for acquisition and tracking of light sources in a transient event rich environment

    NASA Technical Reports Server (NTRS)

    Kissh, Frank (Inventor); Flynn, David (Inventor); Fowski, Walter (Inventor); Abreu, Rene (Inventor); Miklus, Kenneth (Inventor); Bolin, Kenneth (Inventor)

    1993-01-01

    A method and apparatus for tracking a light source in a transient event rich environment locks on to a light source incident on a field-of-view 1 of a charge-coupled-device (CCD) array 6, validates the permanence of said light source and transmits data relating to the brilliance and location of said light source if said light source is determined to be permanent.

  20. Swift Follow-up Observations of Candidate Gravitational-wave Transient Events

    NASA Astrophysics Data System (ADS)

    Evans, P. A.; Fridriksson, J. K.; Gehrels, N.; Homan, J.; Osborne, J. P.; Siegel, M.; Beardmore, A.; Handbauer, P.; Gelbord, J.; Kennea, J. A.; Smith, M.; Zhu, Q.; LIGO Scientific Collaboration; Virgo Collaboration; Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Ast, S.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballardin, G.; Ballmer, S.; Bao, Y.; Barayoga, J. C. B.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Beck, D.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Benacquista, M.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bhadbade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bond, C.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet-Castell, J.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chalermsongsak, T.; Charlton, P.; Chassande-Mottin, E.; Chen, W.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Clayton, J. H.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colacino, C. N.; Colla, A.; Colombini, M.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Coulon, J.-P.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, R. M.; Dahl, K.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Dent, T.; Dergachev, V.; DeRosa, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Emilio, M. Di Paolo; Di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorsher, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Eikenberry, S.; Endrőczi, G.; Engel, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Farr, B. F.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M. A.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P. J.; Fyffe, M.; Gair, J.; Galimberti, M.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gáspár, M. E.; Gelencser, G.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Heefner, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Hough, J.; Howell, E. J.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Izumi, K.; Jacobson, M.; James, E.; Jang, Y. J.; Jaranowski, P.; Jesse, E.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Keitel, D.; Kelley, D.; Kells, W.; Keppel, D. G.; Keresztes, Z.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, H.; Kim, K.; Kim, N.; Kim, Y. M.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Lam, P. K.; Landry, M.; Langley, A.; Lantz, B.; Lastzka, N.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leong, J. R.; Leonor, I.; Leroy, N.; Letendre, N.; Lhuillier, V.; Li, J.; Li, T. G. F.; Lindquist, P. E.; Litvine, V.; Liu, Y.; Liu, Z.; Lockerbie, N. A.; Lodhia, D.; Logue, J.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McDaniel, P.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menéndez, D. F.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morgia, A.; Mori, T.; Morriss, S. R.; Mosca, S.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nash, T.; Naticchioni, L.; Necula, V.; Nelson, J.; Neri, I.; Newton, G.; Nguyen, T.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Oldenberg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Penn, S.; Perreca, A.; Persichetti, G.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pihlaja, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Poggiani, R.; Pöld, J.; Postiglione, F.; Poux, C.; Prato, M.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, M.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sankar, S.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R. L.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Somiya, K.; Sorazu, B.; Speirits, F. C.; Sperandio, L.; Stefszky, M.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S. E.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Taffarello, L.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Vahlbruch, H.; Vajente, G.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vitale, S.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Wallace, L.; Wan, Y.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wiesner, K.; Wilkinson, C.; Willems, P. A.; Williams, L.; Williams, R.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Wittel, H.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.

    2012-12-01

    We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.

  1. Swift Follow-Up Observations of Candidate Gravitational-Wave Transient Events

    NASA Technical Reports Server (NTRS)

    Evans, P. A.; Fridriksson, J. K.; Gehrels, N.; Homan, J.; Osborne, J. P.; Siegel, M.; Beardmore, A.; Handbauer, P.; Gelbord, J.; Kennea, J. A.; Smith, M.; Zhu, Q.; Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Blackburn, J. K.; Camp, J. B.; Kanner, J. B.

    2012-01-01

    We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.

  2. Observations of a transient event in the subsolar magnetosheath during strongly northward IMF

    NASA Astrophysics Data System (ADS)

    Dias Silveira, M. V.; Sibeck, D. G.; Gonzalez, W. D.; Koga, D.

    2013-12-01

    We present multipoint THEMIS observation of a transient event in the subsolar magnetosheath on July 10, 2007. The event exhibits some features of a flux transfer event, such as a bipolar variation in the magnetic field component normal to the nominal magnetopause centered on a peak in the total magnetic field strength. Four THEMIS spacecraft were in the magnetosheath and one in the magnetosphere. Timing analysis and the absence of flow perturbation suggest that the event is a small scale structure (~0.12 Re in the direction of the flow) moving with the background magnetosheath flow. Despite the inferred small size of the event, THC and THD both observed large amplitude (~40 nT) bipolar magnetic field signatures normal to the nominal magnetopause. Nearby spacecraft THE (only 0.2 Re further outward in the Xgsm direction) observed no significant magnetic field perturbation. Neither did THB or THA, located further away in the magnetosheath and magnetosphere, respectively. During the event, the IMF was strongly northward (approximately 20nT), which does not favor subsolar magnetic reconnection. Inside the structure, the magnetic field briefly rotates 90° away from northward to dawnward. Ions stream antiparallel to the magnetic field in the magnetosheath, parallel to the magnetic field in the event.

  3. SAS 3 observations of two X-ray transient events with precursors

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.; Lewin, W. H. G.; Doty, J.; Jernigan, J. G.; Haney, M.; Richardson, J. A.

    1978-01-01

    SAS 3 has observed two unusual fast transient X-ray events from different sources, one lasting about 150 s and one, approximately 1500 s. Both events were preceded by precursor pulses which lasted a few seconds and which rose and fell in less than 0.4 s. The precursors were separated from the 'main' events by several seconds, during which no X-rays were detected. There are similarities between the two main events and X-ray bursts in both their temporal and spectral evolution. The spectra of the main events started out much softer than the spectra of the precursors, became harder as they approached maximum intensity, and softened as they decayed. In the 1500-s event, X-rays with energies greater than 10 keV were delayed by about 80 s compared with 1.5-6-keV X-rays. A blackbody fit to the spectral data of the main event of approximately 1500-s duration gives a maximum temperature of 29 million K and a radius for the emitting region of at least about 9 km (at a distance of 10 kpc); this is similar to the temperature and sizes found for several X-ray burst sources.

  4. Statistics and properties of transient luminous events found in the 1999 Sprites Balloon Campaign

    NASA Astrophysics Data System (ADS)

    Bhusal, L.; Bering, E. A., III; Benbrook, J. R.; Garrett, J. A.; Paredes, A. M.; Wescott, E. M.; Moudry, D. R.; Sentman, D. D.; Stenbaek-Nielsen, H. C.; Lyons, W. A.

    2004-01-01

    Historically, the process of transient luminous event (TLE) detection has required an alert human observer on a low light level television (LLTV) monitor, either in real time or playback. The 1999 Sprites Balloon Campaign payloads had all-sky upward looking photometers not sensitive to events below the balloons. The photometer data was examined at the time of National Lightning Detection Network (NLDN) lightening strokes to find TLEs that were missed visually. 3602 events were analyzed in 4.1 h of storm time. Threshold current moments of ˜50 kA km for the positive cloud to ground (+CG) TLEs and ˜-5 kA km for negative cloud to ground (-CG) TLEs are found.

  5. Transient Astronomical Events as Inspiration Sources of Medieval and Renaissance Art

    NASA Astrophysics Data System (ADS)

    Incerti, M.; Bònoli, F.; Polcaro, V. F.

    2011-06-01

    It is known long since that a number of exceptional and highly impressive astronomical events have been represented in Medieval artworks. We just remember the Bayeux Tapestry and Giotto's The Adoration of the Magi in the Scrovegni Chapel in Padua, representing the P/Halley comet transits of 1067 and 1301, respectively, while The Apparition of Star to Magi fresco in the San Pietro in Valle Abbey in Ferentillo (1182) has been suggested to represent the 1181 supernova. However, no systematic survey of figurative Medieval and Renaissance art has been performed to date, in order to analyzing the role of transient astronomical events as inspiration sources of artworks in these epochs. In this work, we analyze a significant number of artworks, dated between the 9th and 16th century and representing figurative elements in some way connected with astronomy, in order to evaluate if they have been influenced by coeval extraordinary astronomical events.

  6. Possible transient creep events in a brittle-ductile continental crust: observations, experiments and potential models.

    NASA Astrophysics Data System (ADS)

    Lavier, Luc

    2016-04-01

    In a given tectonic province and over thousands to millions of years, slip on faults is believed to be constant and approximately equal to the local tectonic rate in agreement with rigid plate tectonic theory. In this model the ductile lower crust flows in response to this steady plate motion. Moreover brittle and ductile behaviors interact only at a sharp boundary defined as the brittle ductile transition (BDT). However in the continental lithosphere brittle and ductile behavior may coexist over a large range of pressure and temperature conditions for different mineral compositions. This generates heterogeneities in the brittle and ductile crust that are often ignored in models of shear zones. We hypothesize that the interaction between brittle (elastic) and ductile (viscous) behavior may cause deviations from steady-state slip and generates transient creep events on shear zones that release many meters of creep over years to thousands of years marked by a single period of tectonic activity followed by quiescence. We present a set of numerical and analytical models, analogue experiments as well as some observations in nature that may support this hypothesis. In this presentation we extend an analytic formulation to model creep events within shear zones at the transition between brittle and ductile behavior in the crust. We assume that creep events are triggered by a set of interconnected fractures modeled as propagating dislocations. The amount of connectivity controls the nature and the intensity of the transient creep events. The shear zone behaves as a forced damped oscillator that can release strain accumulated during jammed/locked periods. The creep can be over-, critically-, or under-damped. The time scale of the events may vary between seconds to thousands of years depending on the viscous, elastic and plastic (fractures) properties of the shear zone.

  7. Variability in the 2MASS calibration fields: a search for transient obscuration events

    NASA Astrophysics Data System (ADS)

    Quillen, Alice C.; Ciocca, Marco; Carlin, Jeffrey L.; Bell, Cameron P. M.; Meng, Zeyang

    2014-07-01

    We searched the light curves of over 40 000 stars in the Two Micron All Sky Survey (2MASS) calibration data base, spanning approximately 4 yr, for objects that have significant day-long dimming events. We also searched the multi-colour light curves for red-dimming events that could be due to transient extinction. In the colour-independent sigma-limited search, we found 46 previously unrecognized eclipsing binaries, 6 previously unrecognized periodic variable stars likely to be intrinsic pulsators and 21 young stellar objects in the ρ Ophiuchus star formation region previously studied by Parks et al. An additional 11 objects exhibited dimming events, and most of these are unclassified. The search for red-dimming events primarily reveals a population of low-luminosity active galaxies that become bluer when they are brighter, and variable young stellar objects exhibiting high cross-correlation coefficients between colour and brightness. The young stellar objects primarily exhibit brightness and colour variations in the direction of interstellar extinction whereas the active galaxies can have a bowed distribution in colour and magnitude with reduced variation in colour when the object is brightest. Among the objects that are usually quiescent (not strongly variable), we failed to find any dimming events deeper than 0.2 mag and lasting longer than a day. Two of the young stellar objects, however, dimmed by 0.2 mag for longer than a day without strong colour variation.

  8. Mechanism of single-event transient pulse quenching between dummy gate isolated logic nodes

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Jun; Chi, Ya-Qing; Liang, Bin

    2015-01-01

    As integrated circuits scale down in size, a single high-energy ion strike often affects multiple adjacent logic nodes. The so-called single-event transient (SET) pulse quenching induced by single-event charge sharing collection has been widely studied. In this paper, SET pulse quenching enhancement is found in dummy gate isolated adjacent logic nodes compared with that isolated by the common shallow trench isolation (STI). The physical mechanism is studied in depth and this isolation technique is explored for SET mitigation in combinational standard cells. Three-dimensional (3D) technology computer-aided design simulation (TCAD) results show that this technique can achieve efficient SET mitigation. Project supported by the National Natural Science Foundation of China (Grant No. 61376109) and the Opening Project of National Key Laboratory of Science and Technology on Reliability Physics and Application Technology of Electrical Component, China (Grant No. ZHD201202).

  9. Total Dose Effects on Single Event Transients in Digital CMOS and Linear Bipolar Circuits

    NASA Technical Reports Server (NTRS)

    Buchner, S.; McMorrow, D.; Sibley, M.; Eaton, P.; Mavis, D.; Dusseau, L.; Roche, N. J-H.; Bernard, M.

    2009-01-01

    This presentation discusses the effects of ionizing radiation on single event transients (SETs) in circuits. The exposure of integrated circuits to ionizing radiation changes electrical parameters. The total ionizing dose effect is observed in both complementary metal-oxide-semiconductor (CMOS) and bipolar circuits. In bipolar circuits, transistors exhibit grain degradation, while in CMOS circuits, transistors exhibit threshold voltage shifts. Changes in electrical parameters can cause changes in single event upset(SEU)/SET rates. Depending on the effect, the rates may increase or decrease. Therefore, measures taken for SEU/SET mitigation might work at the beginning of a mission but not at the end following TID exposure. The effect of TID on SET rates should be considered if SETs cannot be tolerated.

  10. Modeling and analysis of transient vehicle underhood thermo- hydrodynamic events using computational fluid dynamics and high performance computing.

    SciTech Connect

    Tentner, A.; Froehle, P.; Wang, C.; Nuclear Engineering Division

    2004-01-01

    This work has explored the preliminary design of a Computational Fluid Dynamics (CFD) tool for the analysis of transient vehicle underhood thermo-hydrodynamic events using high performance computing platforms. The goal of this tool will be to extend the capabilities of an existing established CFD code, STAR-CD, allowing the car manufacturers to analyze the impact of transient operational events on the underhood thermal management by exploiting the computational efficiency of modern high performance computing systems. In particular, the project has focused on the CFD modeling of the radiator behavior during a specified transient. The 3-D radiator calculations were performed using STAR-CD, which can perform both steady-state and transient calculations, on the cluster computer available at ANL in the Nuclear Engineering Division. Specified transient boundary conditions, based on experimental data provided by Adapco and DaimlerChrysler were used. The possibility of using STAR-CD in a transient mode for the entire period of time analyzed has been compared with other strategies which involve the use of STAR-CD in a steady-state mode at specified time intervals, while transient heat transfer calculations would be performed for the rest of the time. The results of these calculations have been compared with the experimental data provided by Adapco/DaimlerChrysler and recommendations for future development of an optimal strategy for the CFD modeling of transient thermo-hydrodynamic events have been made. The results of this work open the way for the development of a CFD tool for the transient analysis of underhood thermo-hydrodynamic events, which will allow the integrated transient thermal analysis of the entire cooling system, including both the engine block and the radiator, on high performance computing systems.

  11. Modeling and analysis of transient vehicle underhood thermo - hydrodynamic events using computational fluid dynamics and high performance computing.

    SciTech Connect

    Froehle, P.; Tentner, A.; Wang, C.

    2003-09-05

    This work has explored the preliminary design of a Computational Fluid Dynamics (CFD) tool for the analysis of transient vehicle underhood thermo-hydrodynamic events using high performance computing platforms. The goal of this tool will be to extend the capabilities of an existing established CFD code, STAR-CD, allowing the car manufacturers to analyze the impact of transient operational events on the underhood thermal management by exploiting the computational efficiency of modern high performance computing systems. In particular, the project has focused on the CFD modeling of the radiator behavior during a specified transient. The 3-D radiator calculations were performed using STAR-CD, which can perform both steady-state and transient calculations, on the cluster computer available at ANL in the Nuclear Engineering Division. Specified transient boundary conditions, based on experimental data provided by Adapco and DaimlerChrysler were used. The possibility of using STAR-CD in a transient mode for the entire period of time analyzed has been compared with other strategies which involve the use of STAR-CD in a steady-state mode at specified time intervals, while transient heat transfer calculations would be performed for the rest of the time. The results of these calculations have been compared with the experimental data provided by Adapco/DaimlerChrysler and recommendations for future development of an optimal strategy for the CFD modeling of transient thermo-hydrodynamic events have been made. The results of this work open the way for the development of a CFD tool for the transient analysis of underhood thermo-hydrodynamic events, which will allow the integrated transient thermal analysis of the entire cooling system, including both the engine block and the radiator, on high performance computing systems.

  12. Possible Detection of Volcanic Activity on Europa: Analysis of An Optical Transient Event

    NASA Astrophysics Data System (ADS)

    de La Fuente Marcos, R.; Nissar, A.

    2002-06-01

    Europa's low crater density suggests that geological activity has continued to the present epoch, leading to the possibility that current resurfacing events might be detectable. CCD observations were carried out with a ST-6 camera at the 0.5 m Mons Cassegrain telescope (Izaña Observatory, Tenerife,Canary Islands, Spain) during the night between 2 3 October 1999. Our images show a transient bright feature on the Galilean satellite. These images are analyzed here with the purpose of understanding the nature of the transient phenomena as it could be the result of explosive venting on the surface of the Jovian satellite. By comparison, we use NASA Infrared Telescope Facility images of two Io hot spots taken on12 October 1990. Although we mainly restrict our discussion on apossible eruptive nature of the observed spots, we also consider other alternative mechanisms able to produce bright events. In particular, an interaction between charged material being ejected from Europa and the Jovian magnetosphere cannot be entirely ruled out. If confirmed, this result would lend support for the existence of active resurfacing in Europa.

  13. Migration of seismic scatterers associated with the 1993 Parkfield aseismic transient event.

    PubMed

    Niu, Fenglin; Silver, Paul G; Nadeau, Robert M; McEvilly, Thomas V

    2003-12-01

    The time-varying deformation field within a fault zone, particularly at depths where earthquakes occur, is important for understanding fault behaviour and its relation to earthquake occurrence. But detection of this temporal variation has been extremely difficult, although laboratory studies have long suggested that certain structural changes, such as the properties of crustal fractures, should be seismically detectable. Here we present evidence that such structural changes are indeed observable. In particular, we find a systematic temporal variation in the seismograms of repeat microearthquakes that occurred on the Parkfield segment of the San Andreas fault over the decade 1987-97. Our analysis reveals a change of the order of 10 m in the location of scatterers which plausibly lie within the fault zone at a depth of approximately 3 km. The motion of the scatterers is coincident, in space and time, with the onset of a well documented aseismic transient (deformation event). We speculate that this structural change is the result of a stress-induced redistribution of fluids in fluid-filled fractures caused by the transient event. PMID:14654837

  14. Very-high energy observation of the peculiar transient event Swift J1644+57 with the MAGIC telescopes

    NASA Astrophysics Data System (ADS)

    Lombardi, S.; Carosi, A.; Antonelli, L. A.; de Almeida, U. Barres; Covino, S.; Persic, M.; Tavecchio, F.; MAGIC Collaboration

    2012-12-01

    On March 28th 2011, the Burst Alert Telescope (BAT) on board the Swift satellite detected a new transient event at first hand classified as a Gamma Ray Burst (GRB). However, the unusual X-ray flaring activity observed from a few hours up to days after the onset of the event pointed to a different nature for it. The long lasting activity in the X-ray band and the complex light curve behaviour with significant source re-brightening observed both in the near-infrared (near-IR) and radio band suggested its interpretation as a tidal disruption event "switching on" a dormant black hole in the nucleus of the host galaxy and giving start to an outflowing jet of relativistic matter. MAGIC observations started nearly 2.5 days after the trigger time and were carried on for about 18 days, collecting a total of 28 hours of data during dark time at a mean zenith angle of 35° No clear evidence for emission above an energy threshold of ~ 100 GeV was found.

  15. Transient haemodynamic events in neurologically compromised infants: a simultaneous EEG and diffuse optical imaging study.

    PubMed

    Cooper, R J; Hebden, Jeremy C; O'Reilly, H; Mitra, S; Michell, A W; Everdell, N L; Gibson, A P; Austin, T

    2011-04-15

    We describe a series of novel simultaneous EEG and diffuse optical imaging studies of newborn infants. These experiments provide evidence of large, transient haemodynamic events which occur repeatedly and consistently within and across several infants with neurological damage, all of whom were diagnosed with seizures. A simple but independent process of rejecting artifacts and identifying events within diffuse optical imaging data is described, and this process is applied to data from 4 neurologically damaged neonates and from 19 healthy, age-matched controls. This method results in the consistent identification of events in three out of four of the neurologically damaged infant group which are dominated by a slow (>30s) and significant increase in oxyhaemoglobin concentration, followed by a rapid and significant decrease before a slow return to baseline. No comparable events are found in any of our control data sets. The importance and physiological implications of our findings are discussed, as is the suitability of a combined EEG and diffuse optical imaging approach to the study and monitoring of neonatal brain injury. PMID:21255658

  16. Transient ischaemic attacks: which patients are at high (and low) risk of serious vascular events?

    PubMed Central

    Hankey, G J; Slattery, J M; Warlow, C P

    1992-01-01

    The aims of this study were to determine the important prognostic factors at presentation which identify patients with transient ischaemic attacks (TIA) who are at high risk (and low risk) of serious vascular events and to derive a prediction model (equation) for each of the major vascular outcome events. A cohort of 469 TIA patients referred to a University hospital, without prior stroke, were evaluated prospectively and followed up over a mean period of 4.1 years (range 1-10 years). The major outcome events of interest were 1) stroke 2) coronary event and 3) stroke, myocardial infarction or vascular death (whichever occurred first). Prognostic factors and their hazard ratios were identified by means of the Cox proportional hazards multiple regression analysis. The significant adverse prognostic factors (in order of strength of association) for stroke were an increasing number of TIAs in the three months before presentation, increasing age, peripheral vascular disease, left ventricular hypertrophy and TIAs of the brain (compared with the eye); the prognostic factors for coronary event were increasing age, ischaemic heart disease, male sex, and a combination of carotid and vertebrobasilar TIAs at presentation; and for stroke, myocardial infarction or vascular death they were increasing age, peripheral vascular disease, increasing number of TIAs in the three months before presentation, male sex, a combination of carotid and vertebrobasilar TIAs at presentation, TIAs of the brain (compared with the eye), left ventricular hypertrophy and the eye), left ventricular hypertrophy and the eye), left ventricular hypertrophy and the presence of residual neurological signs after the TIA. Prediction models (equations) of both the relative risk and absolute risk of each of the major outcome events were produced, based on the presence or level of the significant prognostic factors and their hazard. Before it can be concluded that our equations accurately predict prognosis and

  17. Spatiotemporal evolution of a transient slip event on the San Andreas fault near Parkfield, California

    USGS Publications Warehouse

    Murray, J.R.; Segall, P.

    2005-01-01

    In 1993 several baselines of the two-color electronic distance meter (EDM) network at Parkfield, California, deviated from their long-term rates, coincident with anomalous observations from nearby strain meters and a creep meter, as well as an increase in microseismicity. Between October 1992 and December 1994, three M ??? 4.5 earthquakes occurred beneath Middle Mountain, near the hypocenter of the 1934 and 1966 Parkfield M6 events. We analyzed the two-color EDM data using a Kalman-filtering based technique to image the spatiotemporal evolution of slip on the fault at Parkfield between the mid-1980s and 2003. This method accounts for localized random walk motion of the geodetic monuments and a prominent seasonal signal that affects many baselines. We find that a slip rate increase occurred between January 1993 and July 1996 on the upper 8 km of the fault near Middle Mountain. The peak estimated slip rate during this time was 49 mm/yr, which exceeds the long-term geologic rate of ???35 mm/yr. The slip rate evolution appears episodic, with an initial modest increase after the M4.3 earthquake and a much larger jump following the shallower M4.7 event in December 1994. This temporal correlation between inferred slip and seismicity suggests that the moderate earthquakes triggered the aseismic fault slip. The EDM data cannot resolve whether transient slip propagated across the nucleation zone of the 1934 and 1966 M6 Parkfield earthquakes. However, transient slip and its associated stress release in the hypocentral area of previous Parkfield events is consistent with the nucleation of the 2004 M6 Parkfield earthquake elsewhere on the fault. Copyright 2005 by the American Geophysical Union.

  18. Sedimentological Signatures of Transient Depositional Events in the Cariaco Basin, Venezuela

    NASA Astrophysics Data System (ADS)

    Elmore, A. C.; Thunell, R. C.; Black, D. E.; Murray, R. W.; Martinez, N. C.

    2004-12-01

    The varved sediments that have accumulated in the Cariaco Basin throughout the Holocene provide a detailed archive of the region's climatic history, and act as a historical record for the occurrence of phenomena such as earthquakes and coastal flooding. In this study we compare the sedimentological characteristics of lithogenic material collected from the water column during transient depositional events to those of normal hemipelagic sedimentation in the basin. Specifically, we have examined the clay mineralogy and grain size distribution of detrital material delivered to the basin by the July 9, 1997 earthquake near Cumana, Venezuela and the coastal flooding of Venezuela in late 1999. The sample material used in our study was collected as part of an ongoing sediment trap time series in the Cariaco Basin. The sedimentological signatures associated with these two events are distinctive from the typical lithogenic input to the basin. Preliminary data for biweekly samples collected from 1997-1999 shows a tri-modal particle size distribution, with peaks at 3, 22, and 80 im. However, material collected from the deep basin immediately following the 1997 earthquake is characterized by a particle diameter distribution at 6 and 22 im with a smaller than normal peak at 80 im; this variance suggests an alternate source of material was delivered to the basin via a turbidity flow induced by the earthquake. Supporting this theory, the clay mineralogy of the same sediment trap samples shows a higher than average ratio of kaolinite to quartz for sediments delivered to the basin following both the earthquake and flooding. We hope to extend the use of these sedimentological methods to identify past transient depositional events in Cariaco Basin cores.

  19. EVENT84 user's manual: a computer code for analyzing explosion-induced gas-dynamic transients in flow networks

    SciTech Connect

    Martin, R.A.; Wilson, T.L.

    1984-12-01

    This manual supports the computer code EVENT84, which can predict explosion-induced gas-dynamic transients in flow networks. The code can model transients in any arbitrarily designated network of building rooms and ventilation systems. A lumped-parameter formulation is used. EVENT84 was designed to provide a safety analysis tool for he nuclear, chemical, and mining industries. It is particularly suitable for calculating the detailed effects of explosions in the far field using a parametric representation of the explosive event. The code input and a sample problem that illustrates its capabilities are provided.

  20. Complex event extraction at PubMed scale

    PubMed Central

    Björne, Jari; Ginter, Filip; Pyysalo, Sampo; Tsujii, Jun'ichi; Salakoski, Tapio

    2010-01-01

    Motivation: There has recently been a notable shift in biomedical information extraction (IE) from relation models toward the more expressive event model, facilitated by the maturation of basic tools for biomedical text analysis and the availability of manually annotated resources. The event model allows detailed representation of complex natural language statements and can support a number of advanced text mining applications ranging from semantic search to pathway extraction. A recent collaborative evaluation demonstrated the potential of event extraction systems, yet there have so far been no studies of the generalization ability of the systems nor the feasibility of large-scale extraction. Results: This study considers event-based IE at PubMed scale. We introduce a system combining publicly available, state-of-the-art methods for domain parsing, named entity recognition and event extraction, and test the system on a representative 1% sample of all PubMed citations. We present the first evaluation of the generalization performance of event extraction systems to this scale and show that despite its computational complexity, event extraction from the entire PubMed is feasible. We further illustrate the value of the extraction approach through a number of analyses of the extracted information. Availability: The event detection system and extracted data are open source licensed and available at http://bionlp.utu.fi/. Contact: jari.bjorne@utu.fi PMID:20529932

  1. Transient analysis of a flywheel battery containment during a full rotor burst event.

    SciTech Connect

    Hsieh, B. J.

    1998-04-17

    Flywheels are being developed for use in an Advanced Locomotive Propulsion System (ALPS) targeted for use in high speed passenger rail service. The ALPS combines high performance, high speed gas turbines, motor/generators and flywheels to provide a light-weight, fuel-efficient power system. Such a system is necessary to avoid the high cost of railway electrification, as is currently done for high speed rail service (>100mph) since diesels are too heavy. The light-weight flywheel rotors are made from multilayered composite materials, and are operated at extremely high energy levels. Metal containment structures have been designed to enclose the rotors and provide encapsulation of the rotor during postulated failure events. One such event is a burst mode failure of the rotor in which the composite rim is assumed to burst into debris that impacts against the containment. This paper presents a finite element simulation of the transient structural response of a subscale metal flywheel containment structure to a rotor burst event.

  2. Neural mechanisms of evoked oscillations: stability and interaction with transient events.

    PubMed

    Moratti, Stephan; Clementz, Brett A; Gao, Yuan; Ortiz, Tomás; Keil, Andreas

    2007-12-01

    There is increasing evidence that early event-related potentials are a result of phase alignment of ongoing background oscillations of the electroencephalogram rather than additive amplitude modulation. Steady state visual-evoked potentials (ssVEPs) can be recorded using an intensity modulated stimulus, resulting in an evoked brain response at a known frequency, i.e. the stimulation frequency. Given this property, the ssVEP is ideally suited for examining the relationship between single-trial fluctuations in phase/amplitude and the evoked brain potential resulting from averaging across trials. To address this issue, the current study investigated the contribution of single trial power and intertrial phase locking to ssVEP generation by presenting a peripheral flicker. Further, transient stimuli were presented during flicker and at three increasing latency lags following flicker offset to examine (1) to what extent a stimulus can disturb the ssVEP oscillation and (2) how phase alignment during P1-N1-P2 time windows is affected during presence of evoked oscillations. The former assessment evaluates the stability of ssVEPs and the latter the phase alignment processes to transient stimuli under experimentally induced background oscillations. We observed that ssVEPs are a result of phase alignment rather than single trial amplitude modulation. In addition, ssVEP oscillations were not disturbed by transient stimuli. Finally, phase alignment in P1-N1-P2 time windows was distorted during and shortly after steady state stimulation. We conclude that ssVEPs represent strongly phase locked oscillations sharing the same generation mechanisms as early evoked potentials. PMID:17274017

  3. Studies on the high-energy follow-up of gravitational wave transient events

    NASA Astrophysics Data System (ADS)

    Razzano, Massimiliano; Patricelli, Barbara; Cella, Giancarlo; Fidecaro, Francesco; Pian, Elena; Stamerra, Antonio; Branchesi, Marica

    2016-05-01

    Second-generation gravitational wave interferometers, such as Advanced LIGO and Advanced Virgo, will soon reach sensitivities sufficient to first detect gravitational waves and open a new era in the multi-messenger investigations of the cosmos. The most violent and energetic astrophysical phenomena, including the mergers of compact objects or the core collapse of massive stars, are promising sources of gravitational waves, and are thought to be connected with transient phenomena such as Gamma Ray Bursts and supernovae. Combined observations of gravitational and electromagnetic signals from these events will thus provide a unique opportunity to unveil their progenitors and study the physics of compact objects. In particular, gamma-ray ground-based and space observatories such as Fermi or the Air Cherenkov Telescopes will be crucial to observe the high-energy electromagnetic counterparts of transient gravitational wave signals and provide a robust identification based on a precise sky localization. We will report on our studies of possible joint observation strategies carried on by gravitational interferometers and gamma-ray telescopes, with particular attention to the high-energy follow-up of Gamma Ray Bursts.

  4. Single Event Transients in Voltage Regulators for FPGA Power Supply Applications

    NASA Technical Reports Server (NTRS)

    Poivey, Christian; Sanders, Anthony; Kim, Hak; Phan, Anthony; Forney, Jim; LaBel, Kenneth A.; Karsh, Jeremy; Pursley, Scott; Kleyner, Igor; Katz, Richard

    2006-01-01

    As with other bipolar analog devices, voltage regulators are known to be sensitive to single event transients (SET). In typical applications, large output capacitors are used to provide noise immunity. Therefore, since SET amplitude and duration are generally small, they are often of secondary importance due to this capacitance filtering. In low voltage applications, however, even small SET are a concern. Over-voltages may cause destructive conditions. Under-voltages may cause functional interrupts and may also trigger electrical latchup conditions. In addition, internal protection circuits which are affected by load as well as internal thermal effects can also be triggered from heavy ions, causing dropouts or shutdown ranging from milliseconds to seconds. In the case of FPGA power supplies applications, SETS are critical. For example, in the case of Actel FPGA RTAX family, core power supply voltage is 1.5V. Manufacturer specifies an absolute maximum rating of 1.6V and recommended operating conditions between 1.425V and 1.575V. Therefore, according to the manufacturer, any transient of amplitude greater than 75 mV can disrupt normal circuit functions, and overvoltages greater than 100 mV may damage the FPGA. We tested five low dropout voltage regulators for SET sensitivity under a large range of circuit application conditions.

  5. High-energy follow-up studies of gravitational wave transient events

    NASA Astrophysics Data System (ADS)

    Razzano, Massimiliano; Branchesi, Marica; Cella, Giancarlo; Fidecaro, Francesco; Mapelli, Michela; Patricelli, Barbara; Pian, Elena; Stamerra, Antonio

    2015-08-01

    Second-generation gravitational interferometers, such as Advanced LIGO and Advanced Virgo, will soon reach sensitivities sufficient to first detect gravitational waves and open a new era in the multimessenger investigations of the cosmos. The most violent and energetic astrophysical phenomena, including the mergers of compact objects or the core collapse of massive stars, are promising sources of gravitational waves, and are thought to be connected with transient phenomena such as Gamma Ray Bursts and supernovae. Combined observations of gravitational and electromagnetic signals from these events will thus provide an unique opportunity to unveil their progenitors and study the physics of compact objects. In particular, gamma-ray ground-based and space observatories such as Fermi or the Air Cherenkov Telescopes will be crucial to observe the high-energy electromagnetic counterparts of transient gravitational wave signals and provide a robust identification based on a precise sky localization. We will report on our studies of possible joint observation strategies carried on by gravitational interferometers and gamma-ray telescopes, with particular attention on the high-energy follow-up of Gamma Ray Bursts.

  6. Characteristics of Thunderstorms and Lightning Flashes Which Produce Mesospheric Transient Luminous Events

    NASA Technical Reports Server (NTRS)

    Lyons, W. A.; Nelson, T. E.; Armstrong, R. A.; Williams, E. R.; Suszcynsky, D. M.; Strabley, R.; Taylor, M.; Gardner, L.

    1999-01-01

    A six year record of optical observations of lightning-induced mesospheric transient luminous events (TLEs) is available from the Yucca Ridge Field Station (YRFS) near Ft. Collins, CO. Climatological analyses reveal sprites and elves occur in a variety of convective storm types, but principally mesoscale convective systems (MCSs) and squall lines. Severe supercell storms rarely produce TLEs, except during their dissipating stage. Few TLEs are observed during storms with radar echo areas <7,500 sq km. Above this size there is a modest correlation with radar areal coverage. A typical High Plains storm produces 45 TLEs over a 143 interval. Sprites and most elves are associated with +CGs. The probability of a TLE increases with peak current. In six storms, 5.1% of +CGs produced TLEs, the number increasing to 32% of +CGs with >75 kA and 52% of +CGs with >100 kA peak current.

  7. Towards an Automated Classification of Transient Events in Synoptic Sky Surveys

    NASA Technical Reports Server (NTRS)

    Djorgovski, S. G.; Donalek, C.; Mahabal, A. A.; Moghaddam, B.; Turmon, M.; Graham, M. J.; Drake, A. J.; Sharma, N.; Chen, Y.

    2011-01-01

    We describe the development of a system for an automated, iterative, real-time classification of transient events discovered in synoptic sky surveys. The system under development incorporates a number of Machine Learning techniques, mostly using Bayesian approaches, due to the sparse nature, heterogeneity, and variable incompleteness of the available data. The classifications are improved iteratively as the new measurements are obtained. One novel featrue is the development of an automated follow-up recommendation engine, that suggest those measruements that would be the most advantageous in terms of resolving classification ambiguities and/or characterization of the astrophysically most interesting objects, given a set of available follow-up assets and their cost funcations. This illustrates the symbiotic relationship of astronomy and applied computer science through the emerging disciplne of AstroInformatics.

  8. First Ground-based Observation of Transient Luminous Events over Southern Africa

    NASA Astrophysics Data System (ADS)

    Nnadih, Ogechukwu; Kosch, Michael; Martinez, Peter

    2016-07-01

    We present the first ground-based observations in southern Africa of Transient Luminous Events (TLEs) in the summer of 2015/16 over convective thunderstorms. For the months of December to February, South Africa has one of the highest lightning stroke rates in the world. This was part of the AfriSprite campaign initiated by the South African National Space Agency. These observations show a variety of fine structures such as tree-like shaped, carrot, angel and jellyfish-shaped sprites. The South African Weather Service array of VLF receivers is used to locate and quantify the magnitude and polarity of the lightning strikes associated with TLEs. We plan to make bi-static as well as multi-wavelength observations in future.

  9. Transient News Events Test: feasibility in assessment of post-temporal lobectomy remote memory deficits.

    PubMed

    Leeman, Beth A; Macklin, Eric A; Schomer, Donald L; O'Connor, Margaret G

    2009-09-01

    Although anterograde memory deficits are well documented in patients with epilepsy, the extent to which remote memory deficits occur is less clear. This is due in part to a lack of reliable methods for assessment. The present study examined the feasibility of using the Transient News Events Test (TNET) to assess remote memory in subjects status post anterior temporal lobectomy (ATL) for the treatment of refractory seizures. Results indicated significantly poorer performance of the patient group compared to healthy controls. The decrement in performance within the patient group was evident only for items from more recent time periods. Reasons for an apparent stability of the most remote memories with ATL and implications regarding hippocampal function are reviewed. In conclusion, the TNET provides a feasible method for assessment of remote memory function in patients with epilepsy, with decrements in performance noted in comparison to a healthy control group in this retrospective study. PMID:19643674

  10. Investigations on heavy ion induced Single-Event Transients (SETs) in highly-scaled FinFETs

    NASA Astrophysics Data System (ADS)

    Gaillardin, M.; Raine, M.; Paillet, P.; Adell, P. C.; Girard, S.; Duhamel, O.; Andrieu, F.; Barraud, S.; Faynot, O.

    2015-12-01

    We investigate Single-Event Transients (SET) in different designs of multiple-gate devices made of FinFETs with various geometries. Heavy ion experimental results are explained by using a thorough charge collection analysis of fast transients measured on dedicated test structures. Multi-level simulations are performed to get new insights into the charge collection mechanisms in multiple-gate devices. Implications for multiple-gate device design hardening are finally discussed.

  11. Vapor shielding models and the energy absorbed by divertor targets during transient events

    NASA Astrophysics Data System (ADS)

    Skovorodin, D. I.; Pshenov, A. A.; Arakcheev, A. S.; Eksaeva, E. A.; Marenkov, E. D.; Krasheninnikov, S. I.

    2016-02-01

    The erosion of divertor targets caused by high heat fluxes during transients is a serious threat to ITER operation, as it is going to be the main factor determining the divertor lifetime. Under the influence of extreme heat fluxes, the surface temperature of plasma facing components can reach some certain threshold, leading to an onset of intense material evaporation. The latter results in formation of cold dense vapor and secondary plasma cloud. This layer effectively absorbs the energy of the incident plasma flow, turning it into its own kinetic and internal energy and radiating it. This so called vapor shielding is a phenomenon that may help mitigating the erosion during transient events. In particular, the vapor shielding results in saturation of energy (per unit surface area) accumulated by the target during single pulse of heat load at some level Emax. Matching this value is one of the possible tests to verify complicated numerical codes, developed to calculate the erosion rate during abnormal events in tokamaks. The paper presents three very different models of vapor shielding, demonstrating that Emax depends strongly on the heat pulse duration, thermodynamic properties, and evaporation energy of the irradiated target material. While its dependence on the other shielding details such as radiation capabilities of material and dynamics of the vapor cloud is logarithmically weak. The reason for this is a strong (exponential) dependence of the target material evaporation rate, and therefore the "strength" of vapor shield on the target surface temperature. As a result, the influence of the vapor shielding phenomena details, such as radiation transport in the vapor cloud and evaporated material dynamics, on the Emax is virtually completely masked by the strong dependence of the evaporation rate on the target surface temperature. However, the very same details define the amount of evaporated particles, needed to provide an effective shielding to the target, and

  12. A case and statistical study of transient magnetic field events at geosynchronous orbit and their solar wind origin

    SciTech Connect

    Borodkova, N.L.; Zastenker, G.N.; Sibeck, D.G.

    1995-04-01

    The authors present a statistical survey of Prognoz 10 solar wind observations at the times of transient (step function and impulsive) variations in the dayside magnetospheric magnetic field strength measured by the GOES 5 and 6 geosynchronous satellites. The results indicate that 51% of the transient magnetospheric events can be associated with corresponding variations in the solar wind dynamic pressure. A further 17% of the events can be associated with fluctuations in the interplanetary magnetic field orientation in the sense previously associated with foreshock pressure pulses. The authors find no tendency for impulsive events at dayside geosynchronous orbit to be associated with north/south fluctuations in the interplanetary magnetic field (IMF) orientation, nor for the events to occur primarily during intervals of southward IMF. The success rate for associating transient events at dayside geosynchronous orbit with solar wind features decreases as Prognoz 10 moves farther from the Earth-Sun line. The observations indicate that variations in the solar wind dynamic pressure and foreshock pressure pulses associated with variations in the IMF cone angle are the predominant causes of large-amplitude transient events observed at dayside geosynchronous orbit. 65 refs., 5 figs., 2 tabs.

  13. Identifying the occurrence of lightning and transient luminous events by nadir spectrophotometric observation

    NASA Astrophysics Data System (ADS)

    Adachi, Toru; Sato, Mitsuteru; Ushio, Tomoo; Yamazaki, Atsushi; Suzuki, Makoto; Kikuchi, Masayuki; Takahashi, Yukihiro; Inan, Umran S.; Linscott, Ivan; Hobara, Yasuhide; Frey, Harald U.; Mende, Stephen B.; Chen, Alfred B.; Hsu, Rue-Ron; Kusunoki, Kenichi

    2016-07-01

    We propose a new technique to identify the occurrence of lightning and transient luminous events (TLEs) using multicolor photometric data obtained by space borne nadir measurements. We estimate the spectral characteristics of lightning and TLEs by converting the optical data obtained by the ISUAL limb experiment to the GLIMS nadir geometry. We find that the estimated spectral shapes of TLE-accompanied lightning are clearly different from those of pure lightning. The obtained results show that (1) the intensity of FUV signals and (2) the ratio of 337/red (609-753 nm) spectral irradiance are useful to identify the occurrence of TLEs. The occurrence probabilities of TLEs are 10%, 40%, 80%, in the case of lightning events having the 337/red spectral irradiance ratio of 0.95, 2.95, 14.79, respectively. By using the 60% criterion of the 337/red ratio and the existence of FUV emissions, we classify the 1039 GLIMS-observed lightning events into 828 pure lightning and 211 TLE-accompanied lightning. Since the GLIMS trigger level is adjusted to observe extremely-bright events, the occurrence probability of TLEs obtained here most probably reflects the characteristics of energetic lightning. The estimated global map is consistent with previously determined distributions: the highest activities of lightning and TLEs are found over the North/South American continents, African continent, and Asian maritime regions. While the absolute occurrence number of pure lightning and TLE-accompanied lightning are found to maximize in the equatorial region, the occurrence probability of TLEs possibly increase somewhat in the mid-latitude region. Since the occurrence probabilities of TLEs are higher over the ocean than over land, it is likely that the GLIMS-observed TLEs are due primarily to elves which tends to occur more frequently over the ocean.

  14. Single event transient modeling and mitigation techniques for mixed-signal delay locked loop (DLL) and clock circuits

    NASA Astrophysics Data System (ADS)

    Maillard, Pierre

    The purpose of this PhD work has been to investigate, model, test, develop and provide hardening techniques and guidelines for the mitigation of single event transients (SETs) in analog mixed-signal (AMS) delay locked loops (DLLs) for radiation-hardened applications. Delay-locked-loops (DLLs) are circuit substructures that are present in complex ASIC and system-on-a-chip designs. These circuits are widely used in on-chip clock distribution systems to reduce clock skew, to reduce jitter noise, and to recover clock signals at regional points within a global clock distribution system. DLLs are critical to the performance of many clock distribution systems, and in turn, the overall performance of the associated integrated system; as such, complex systems often employ multiple DLLs for clock deskew and distribution tasks. In radiation environments such as on-orbit, these critical circuits represent at-risk points of malfunction for large sections of integrated circuits due to vulnerabilities to radiation-generated transients (i.e. single event transients) that fan out across the system. The analysis of single event effects in analog DLLs has shown that each DLL sub-circuit primitive is vulnerable to single event transients. However, we have identified the voltage controlled delay line (VCDL) sub-circuit as the most sensitive to radiation-induced single event effects generating missing clock pulses that increase with the operating frequency of the circuit. This vulnerability increases with multiple instantiation of DLLs as clock distribution nodes throughout an integrated system on a chip. To our knowledge, no complete work in the rad-hard community regarding the hardening of mixed-signal DLLs against single event effects (missing pulses) has been developed. Most of the work present in the literature applies the "brute force" and well-established digital technique of triple modular redundancy (TMR) to the digital subcomponents. We have developed two novel design

  15. Transient paralysis during acupuncture therapy: a case report of an adverse event.

    PubMed

    Beable, Anne

    2013-09-01

    A patient with apparently well-controlled epilepsy with a painful musculoskeletal condition was treated successfully with two sessions of acupuncture. However, 4 h after the first treatment and during the second, an adverse event involving impairment of consciousness occurred. The patient subsequently experienced an increased frequency of complex partial seizures resulting in the loss of his driving licence. A detailed retrospective review of the past medical history indicated that the patient probably had comorbidities in the form of rapid eye movement sleep behaviour disorder and dysfunctional somatosensory/vestibular processing. Acupuncture may have triggered the adverse event via shared neurosubstrates. This adverse event raises possible implications regarding safe clinical acupuncture practice. PMID:23660010

  16. Transient Galactic Cosmic-ray Modulation during Solar Cycle 24: A Comparative Study of Two Prominent Forbush Decrease Events

    NASA Astrophysics Data System (ADS)

    Zhao, L.-L.; Zhang, H.

    2016-08-01

    Forbush decrease (FD) events are of great interest for transient galactic cosmic-ray (GCR) modulation study. In this study, we perform comparative analysis of two prominent Forbush events during cycle 24, occurring on 2012 March 8 (Event 1) and 2015 June 22 (Event 2), utilizing the measurements from the worldwide neutron monitor (NM) network. Despite their comparable magnitudes, the two Forbush events are distinctly different in terms of evolving GCR energy spectrum and energy dependence of the recovery time. The recovery time of Event 1 is strongly dependent on the median energy, compared to the nearly constant recovery time of Event 2 over the studied energy range. Additionally, while the evolutions of the energy spectra during the two FD events exhibit similar variation patterns, the spectrum of Event 2 is significantly harder, especially at the time of deepest depression. These difference are essentially related to their associated solar wind disturbances. Event 1 is associated with a complicated shock-associated interplanetary coronal mass ejection (ICME) disturbance with large radial extent, probably formed by the merging of multiple shocks and transient flows, and which delivered a glancing blow to Earth. Conversely, Event 2 is accompanied by a relatively simple halo ICME with small radial extent that hit Earth more head-on.

  17. Optimal control of transient dynamics in balanced networks supports generation of complex movements.

    PubMed

    Hennequin, Guillaume; Vogels, Tim P; Gerstner, Wulfram

    2014-06-18

    Populations of neurons in motor cortex engage in complex transient dynamics of large amplitude during the execution of limb movements. Traditional network models with stochastically assigned synapses cannot reproduce this behavior. Here we introduce a class of cortical architectures with strong and random excitatory recurrence that is stabilized by intricate, fine-tuned inhibition, optimized from a control theory perspective. Such networks transiently amplify specific activity states and can be used to reliably execute multidimensional movement patterns. Similar to the experimental observations, these transients must be preceded by a steady-state initialization phase from which the network relaxes back into the background state by way of complex internal dynamics. In our networks, excitation and inhibition are as tightly balanced as recently reported in experiments across several brain areas, suggesting inhibitory control of complex excitatory recurrence as a generic organizational principle in cortex. PMID:24945778

  18. The complex correspondence between families and collisional events

    NASA Astrophysics Data System (ADS)

    Milani Comparetti, Andrea

    2015-08-01

    Asteroid families are identified as statistically significant concentrations of asteroids in the space of proper elements. The purpose of family classifications is meant to be the identification of the largest collisional events occurred during the history of the asteroid main belt. However, are the families as found in 1-1 correspondence with ancient collisional events? A recent analysis of larger classifications, based on larger and more accurate datasets of proper elements, indicates that this is not the case. There are multiple cratering events on the same parent body. There are collisional families split into two by the YORP effect. There are subfamilies arising from secondary collisions after the one forming a larger family, and this is not limited to recent events. There are families overlapping in proper elements space but with composition incompatible with a common parent body. There are cases not yet understood, but pointing to a complex collisional history. In total at least 10 cases of complex correpondence between families and collisional events have been identified, more are suspected but not yet supported by enough evidence. The disentagling of these complex collisional histories is an essential step towards the understanding of the asteroid collisional evolution.

  19. Extreme events and natural hazards: The complexity perspective

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-10-01

    Advanced societies have become quite proficient at defending against moderate-size earthquakes, hurricanes, floods, or other natural assaults. What still pose a significant threat, however, are the unknowns, the extremes, the natural phenomena encompassed by the upper tail of the probability distribution. Alongside the large or powerful events, truly extreme natural disasters are those that tie different systems together: an earthquake that causes a tsunami, which leads to flooding, which takes down a nuclear reactor. In the geophysical monograph Extreme Events and Natural Hazards: The Complexity Perspective, editors A. Surjalal Sharma, Armin Bunde, Vijay P. Dimro, and Daniel N. Baker present a lens through which such multidisciplinary phenomena can be understood. In this interview, Eos talks to Sharma about complexity science, predicting extreme events and natural hazards, and the push for "big data."

  20. Ten-year transient luminous events and Earth observations of FORMOSAT-2

    NASA Astrophysics Data System (ADS)

    Chern, Rock Jeng-Shing; Lin, Shin-Fa; Wu, An-Ming

    2015-07-01

    The purpose of this paper is to summarize the enormous contributions of FS2 (FORMOSAT-2 or Formosa satellite #2) in both Earth and transient luminous events (TLEs) observations in 10 years. As a small satellite operated for 10 years (20 May 2004 to 20 May 2014) in orbit, FS2 keeps its two unique characteristics: (1) to orbit 14 revolutions around the Earth per day with daily revisit capability, and (2) to provide the capabilities of Earth observation in sunlight time and TLEs observation in eclipsed time every day. It carries two payloads: the remote sensing instrument (RSI) for Earth imaging in satellite's day time and the imager of sprites and upper atmospheric lightning instrument (ISUAL) for scientific observations in satellite's night time, respectively. Daily revisit capability provides changes of events on Earth in either short time (several days) or long term (several years). Examples include: Indian Ocean earthquake and tsunami (December 2004), disintegration of Wilkins Ice Shelf in Antarctica region (2006-2014, long term), Sichuan earthquake (May 2008), Tohoku earthquake and tsunami (March 2011), polar regions (2006-2014, long term), etc. In the TLEs observation, ISUAL had recorded more than 35,000 events in 10 years with 73.93% elves, 6.54% red sprites, 5.81% halos, 13.42% blue jets and 0.30% gigantic jets. Major contributions of FS2 in this specific scientific area are presented. In particular, current and future research topics on TLEs are discussed. Also, major contributions of FS2's RSI to the United Nations Institute for Training and Research (UNITAR) Operational Satellite Applications Programme (UNOSAT) and Group of Earth Observation System of Systems (GEOSS) are summarized. This paper also addresses briefly the health status of FS2 after working 10 years in orbit.

  1. Transient suppression of heart rate complexity in concussed athletes.

    PubMed

    La Fountaine, Michael F; Heffernan, Kevin S; Gossett, James D; Bauman, William A; De Meersman, Ronald E

    2009-06-15

    Heart rate variability (HRV) and complexity (HRC) were calculated at rest and during an isometric hand grip test (IHGT) within 48-hours (48 h) and two weeks (Week Two) of a concussion in athletes (CG) and control subjects. No differences were present at rest or in HRV during IGHT. HRC was significantly lower in the CG compared to controls at 48 h during IHGT. In CG at Week Two during IHGT, HRC was significantly greater than 48 h observations and not significantly different than controls. The findings suggest that HRC may have utility in detecting efferent cardiac autonomic anomalies within two weeks of concussion. PMID:19303821

  2. A LUMINOUS, FAST RISING UV-TRANSIENT DISCOVERED BY ROTSE: A TIDAL DISRUPTION EVENT?

    SciTech Connect

    Vinkó, J.; Wheeler, J. C.; Chatzopoulos, E.; Marion, G. H.; Yuan, F.; Akerlof, C.; Quimby, R. M.; Ramirez-Ruiz, E.; Guillochon, J.

    2015-01-01

    We present follow-up observations of an optical transient (OT) discovered by ROTSE on 2009 January 21. Photometric monitoring was carried out with ROTSE-IIIb in the optical and Swift in the UV up to +70 days after discovery. The light curve showed a fast rise time of ∼10 days followed by a steep decline over the next 60 days, which was much faster than that implied by {sup 56}Ni—{sup 56}Co radioactive decay. The Sloan Digital Sky Survey Data Release 10 database contains a faint, red object at the position of the OT, which appears slightly extended. This and other lines of evidence suggest that the OT is of extragalactic origin, and this faint object is likely the host galaxy. A sequence of optical spectra obtained with the 9.2 m Hobby-Eberly Telescope between +8 and +45 days after discovery revealed a hot, blue continuum with no visible spectral features. A few weak features that appeared after +30 days probably originated from the underlying host. Fitting synthetic templates to the observed spectrum of the host galaxy revealed a redshift of z = 0.19. At this redshift, the peak magnitude of the OT is close to –22.5, similar to the brightest super-luminous supernovae; however, the lack of identifiable spectral features makes the massive stellar death hypothesis less likely. A more plausible explanation appears to be the tidal disruption of a Sun-like star by the central supermassive black hole. We argue that this transient likely belongs to a class of super-Eddington tidal disruption events.

  3. Total Dose Effects on Single Event Transients in Linear Bipolar Systems

    NASA Technical Reports Server (NTRS)

    Buchner, Stephen; McMorrow, Dale; Bernard, Muriel; Roche, Nicholas; Dusseau, Laurent

    2008-01-01

    Single Event Transients (SETs) originating in linear bipolar integrated circuits are known to undermine the reliability of electronic systems operating in the radiation environment of space. Ionizing particle radiation produces a variety of SETs in linear bipolar circuits. The extent to which these SETs threaten system reliability depends on both their shapes (amplitude and width) and their threshold energies. In general, SETs with large amplitudes and widths are the most likely to propagate from a bipolar circuit's output through a subsystem. The danger these SET pose is that, if they become latched in a follow-on circuit, they could cause an erroneous system response. Long-term exposure of linear bipolar circuits to particle radiation produces total ionizing dose (TID) and/or displacement damage dose (DDD) effects that are characterized by a gradual degradation in some of the circuit's electrical parameters. For example, an operational amplifier's gain-bandwidth product is reduced by exposure to ionizing radiation, and it is this reduction that contributes to the distortion of the SET shapes. In this paper, we compare SETs produced in a pristine LM124 operational amplifier with those produced in one exposed to ionizing radiation for three different operating configurations - voltage follower (VF), inverter with gain (IWG), and non-inverter with gain (NIWG). Each configuration produces a unique set of transient shapes that change following exposure to ionizing radiation. An important finding is that the changes depend on operating configuration; some SETs decrease in amplitude, some remain relatively unchanged, some become narrower and some become broader.

  4. Transient Creep Events and the Transition from Aseismic to Seismic Faulting Observed in Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Schubnel, A.; Brantut, N.; Fortin, J.; Gueguen, Y.

    2008-12-01

    Dry triaxial compression experiments performed on Carrara marble and Volterra Gypsum at confining pressures ranging from 10 to 100MPa revealed an important dependence of the strain rate on the confining stress. At constant shear stress, transient exponential increases in axial strain, similar to transient creep events observed on the field, were observed for small decreases of the confining pressure (1-10MPa), which could eventually lead to ductile failure nucleation. In such case, rupture propagation was silent and slow (several hundreds of seconds), although accompanied by stress drops of the order of several tens of MPas and millimetric slips. However, as the slip velocity increased during failure propagation, continuous acoustic waveform recordings enabled us to illustrate the transition from aseismic to seismic faulting. These experiments provide a clear experimental case of silent, slow localized failure in rocks as a result of an interplay between intragranular plasticity and microcracking. In the case of ductile failure as in the marble, dislocation and twin accumulation is such that cracks propagation steps are small and/or slow, and thus the radiated energy release rate remains small at early stages of rupture and increases with rupture speed. This last observation clearly highlights the dependence of radiated acoustic (and microseismic?) energy during crack propagation not only on the rupture propagation speed and the slip velocity but most importantly on the rock's lithology and rheology. This could have important implications as carbonates are prevalent within sedimentary basins. At even at shallower depths and prevalent within fault gouges, clay minerals are also expected to behave in a similar way.

  5. A statistical survey of 5-MeV proton events at transient interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Kallenrode, May-Britt

    1996-11-01

    Between 1974 and 1985 the two Helios spacecraft observed 351 transient interplanetary shocks. For 5-MeV protons the particle events associated with these shocks can be divided into three groups: (1) events without intensity increase above quiet time or increased background (47%), (2) solar and interplanetary particle (SIP) events consisting of particles accelerated on or close to the Sun (solar or near-Sun component) as well as at the interplanetary shock (24%), and (3) pure interplanetary particle (PIP) events (29%) which consist of particles accelerated at the shock in interplanetary space but do not show evidence for significant or even excess particle acceleration on the Sun. This classification shows that (1) only about half of the shocks accelerate MeV protons in interplanetary space and (2) MeV protons accelerated on the Sun are neither a necessary nor a sufficient condition for the acceleration of MeV protons in interplanetary space. Shock parameters such as speed or shock strength alone do not give an indication for the class of the associated particle event, because in the parameter range which covers most of the shocks, all three classes are distributed rather evenly. However, the shocks strongest in these parameters tend to accelerate particles. The intensity at the time of shock-passage, which can be used as a crude measure for the local acceleration efficiency, is correlated with the local shock speed and the magnetic compression. The correlation coefficients are small but statistically significant, indicating that (1) the correlations are real and (2) the intensity is influenced by additional parameters, which are not necessarily shock inherent. As an example I will show that the local acceleration at the shock decreases roughly symmetrically with increasing distance from the nose of the shock with a median e-folding angle of 10°. Occasionally, larger e-folding angles are observed close to the nose of the shock. The question of how the shock

  6. Complex events in a fault model with interacting asperities

    NASA Astrophysics Data System (ADS)

    Dragoni, Michele; Tallarico, Andrea

    2016-08-01

    The dynamics of a fault with heterogeneous friction is studied by employing a discrete fault model with two asperities of different strengths. The average values of stress, friction and slip on each asperity are considered and the state of the fault is described by the slip deficits of the asperities as functions of time. The fault has three different slipping modes, corresponding to the asperities slipping one at a time or simultaneously. Any seismic event produced by the fault is a sequence of n slipping modes. According to initial conditions, seismic events can be different sequences of slipping modes, implying different moment rates and seismic moments. Each event can be represented geometrically in the state space by an orbit that is the union of n damped Lissajous curves. We focus our interest on events that are sequences of two or more slipping modes: they show a complex stress interchange between the asperities and a complex temporal pattern of slip rate. The initial stress distribution producing these events is not uniform on the fault. We calculate the stress drop, the moment rate and the frequency spectrum of the events, showing how these quantities depend on initial conditions. These events have the greatest seismic moments that can be produced by fault slip. As an example, we model the moment rate of the 1992 Landers, California, earthquake that can be described as the consecutive failure of two asperities, one of which has a double strength than the other, and evaluate the evolution of stress distribution on the fault during the event.

  7. Deep Fusion of Multiple Semantic Cues for Complex Event Recognition.

    PubMed

    Zhang, Xishan; Zhang, Hanwang; Zhang, Yongdong; Yang, Yang; Wang, Meng; Luan, Huanbo; Li, Jintao; Chua, Tat-Seng

    2016-03-01

    We present a deep learning strategy to fuse multiple semantic cues for complex event recognition. In particular, we tackle the recognition task by answering how to jointly analyze human actions (who is doing what), objects (what), and scenes (where). First, each type of semantic features (e.g., human action trajectories) is fed into a corresponding multi-layer feature abstraction pathway, followed by a fusion layer connecting all the different pathways. Second, the correlations of how the semantic cues interacting with each other are learned in an unsupervised cross-modality autoencoder fashion. Finally, by fine-tuning a large-margin objective deployed on this deep architecture, we are able to answer the question on how the semantic cues of who, what, and where compose a complex event. As compared with the traditional feature fusion methods (e.g., various early or late strategies), our method jointly learns the essential higher level features that are most effective for fusion and recognition. We perform extensive experiments on two real-world complex event video benchmarks, MED'11 and CCV, and demonstrate that our method outperforms the best published results by 21% and 11%, respectively, on an event recognition task. PMID:26780785

  8. A case and statistical study of transient magnetic field events at geosynchronous orbit and their solar wind origin

    NASA Technical Reports Server (NTRS)

    Borodkova, N. L.; Zastenker, G. N.; Sibeck, D. G.

    1995-01-01

    We present a statisical survey of Prognoz 10 solar wind observations at the times of transient (step function and impulsive) variations in the dayside magnetospheric magnetic field strength measured by the GOES 5 and 6 geosynchronous satellites. The results indicate that 51% of the magnetospheric events can be associated with corresponding variations in the solar wind dynamic pressure. A further 17% of the events can be associated with fluctuations in the interplanetary magnetic field orientation in the sense previously associated with foreshock pressure pulses. We find no tendency for impulsive events at dayside geosynchronous orbit to be associated with north/south fluctuations in the interplanetary magnetic field (IMF) orientation, nor for the events to occur primarily during intervals of southward IMF. The success rate for associating transient events at dayside geosynchronous orbit with solar wind features decreases as Prognoz 10 moves farther from the Earth-Sun line. The observations indicate that variations in the solar wind dynamic pressure and foreshock pressure pulses associated with variations in the IMF cone angle are the predominant causes of large-amplitude transient events observed at dayside geosynchronous orbit.

  9. A case and statistical study of transient magnetic field events at geosynchronous orbit and their solar wind origin

    NASA Astrophysics Data System (ADS)

    Borodkova, N. L.; Zastenker, G. N.; Sibeck, D. G.

    1995-04-01

    We present a statisical survey of Prognoz 10 solar wind observations at the times of transient (step function and impulsive) variations in the dayside magnetospheric magnetic field strength measured by the GOES 5 and 6 geosynchronous satellites. The results indicate that 51% of the magnetospheric events can be associated with corresponding variations in the solar wind dynamic pressure. A further 17% of the events can be associated with fluctuations in the interplanetary magnetic field orientation in the sense previously associated with foreshock pressure pulses. We find no tendency for impulsive events at dayside geosynchronous orbit to be associated with north/south fluctuations in the interplanetary magnetic field (IMF) orientation, nor for the events to occur primarily during intervals of southward IMF. The success rate for associating transient events at dayside geosynchronous orbit with solar wind features decreases as Prognoz 10 moves farther from the Earth-Sun line. The observations indicate that variations in the solar wind dynamic pressure and foreshock pressure pulses associated with variations in the IMF cone angle are the predominant causes of large-amplitude transient events observed at dayside geosynchronous orbit.

  10. Single-Event Transient Testing of the Crane Aerospace and Electronics SMHF2812D Dual DC-DC Converter

    NASA Technical Reports Server (NTRS)

    Casey, Megan

    2015-01-01

    The purpose of this testing was to characterize the Crane Aerospace & Electronics (Crane) Interpoint SMHF2812D for single-event transient (SET) susceptibility. These data shall be used for flight lot evaluation, as well as qualification by similarity of the SMHF family of converters, all of which use the same active components.

  11. New Space Shuttle Observations of Transient Luminous Events During the MEIDEX

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Price, C.; Israelevitch, P.; Devir, A.; Moalem, M.; Ziv, B.; Levin, Z.; Joseph, J.

    2003-12-01

    The Mediterranean Israeli Dust Experiment (MEIDEX) was conducted on-board the space shuttle Columbia during its last mission in January 2003. Nocturnal observations with a multispectral CCD video camera were targeted above thunderstorms near the Earth's limb, with the aim or recording Transient Luminous Events (TLEs) in the mesosphere. Most of our nighttime observations were conducted in the SE-Pacific (Australia and Papua-New Guinea), equatorial Africa, the southern Indian Ocean and South America. Relevant inputs and information on the active storms during a specific orbit were uplinked to the crew daily. The necessary shuttle attitude maneuvers were deduced based on the use of (almost) real-time IR satellite images and VLF lightning location data that were available on the Internet. In order to enhance the probability of success of each observation, the astronauts were instructed to visually observe lightning activity (easily discernable from the shuttle) and to direct the gimbaled camera toward these regions. A total of more than 8 hours of video obtained during the MEIDEX was saved, and it includes a considerable amount of new sprite data. Most events were captured at ranges 1600-1900 km from the shuttle, using the red filter (665nm). The results suggest the occurrence rate of sprites and elves over oceanic and continental storms may be higher than earlier estimates. Strong enhancements of the brightness of the airglow layer above lightning flashes were observed, with lateral dimensions on the order of 400-500 km. It is assumed that these may be Elves observed edge-on, though it may also be a new type of airglow enhancement. The calculated brightness of these events is in the range 2.2-8.8 MR. This phenomena seems to be widespread and is probably a manifestation of the interaction between lightning EMP and QE fields and the lower nocturnal ionosphere. A unique observation from space of the Congo basin in Africa caught a chain of events where in the span of less

  12. Electrostatic Rate Enhancement and Transient Complex of Protein-Protein Association

    PubMed Central

    Alsallaq, Ramzi; Zhou, Huan-Xiang

    2012-01-01

    The association of two proteins is bounded by the rate at which they, via diffusion, find each other while in appropriate relative orientations. Orientational constraints restrict this rate to ~105 – 106 M−1s−1. Proteins with higher association rates generally have complementary electrostatic surfaces; proteins with lower association rates generally are slowed down by conformational changes upon complex formation. Previous studies (Zhou, Biophys. J. 1997;73:2441–2445) have shown that electrostatic enhancement of the diffusion-limited association rate can be accurately modeled by kD = kD0 exp(−*/ kBT), where kD and kD0 are the rates in the presence and absence of electrostatic interactions, respectively, * is the average electrostatic interaction energy in a “transient-complex” ensemble, and kBT is thermal energy. The transient-complex ensemble separates the bound state from the unbound state. Predictions of the transient-complex theory on four protein complexes were found to agree well with experiment when the electrostatic interaction energy was calculated with the linearized Poisson-Boltzmann (PB) equation (Alsallaq and Zhou, Structure 2007, 15:215–224). Here we show that the agreement is further improved when the nonlinear PB equation is used. These predictions are obtained with the dielectric boundary defined as the protein van der Waals surface. When the dielectric boundary is instead specified as the molecular surface, electrostatic interactions in the transient complex become repulsive and are thus predicted to retard association. Together these results demonstrate that the transient-complex theory is predictive of electrostatic rate enhancement and can help parameterize PB calculations. PMID:17932929

  13. Computer program simplifies transient and steady-state temperature prediction for complex body shapes

    NASA Technical Reports Server (NTRS)

    Giebler, K. N.

    1966-01-01

    Computer program evaluates heat transfer modes and calculates either the transient or steady-state temperature distributions throughout an object of complex shape when heat sources are applied to specified points on the object. It uses an electrothermal model to simulate the conductance, heat capacity, and temperature potential of the object.

  14. Line-edge roughness induced single event transient variation in SOI FinFETs

    NASA Astrophysics Data System (ADS)

    Weikang, Wu; Xia, An; Xiaobo, Jiang; Yehua, Chen; Jingjing, Liu; Xing, Zhang; Ru, Huang

    2015-11-01

    The impact of process induced variation on the response of SOI FinFET to heavy ion irradiation is studied through 3-D TCAD simulation for the first time. When FinFET biased at OFF state configuration (Vgs = 0, Vds = Vdd) is struck by a heavy ion, the drain collects ionizing charges under the electric field and a current pulse (single event transient, SET) is consequently formed. The results reveal that with the presence of line-edge roughness (LER), which is one of the major variation sources in nano-scale FinFETs, the device-to-device variation in terms of SET is observed. In this study, three types of LER are considered: type A has symmetric fin edges, type B has irrelevant fin edges and type C has parallel fin edges. The results show that type A devices have the largest SET variation while type C devices have the smallest variation. Further, the impact of the two main LER parameters, correlation length and root mean square amplitude, on SET variation is discussed as well. The results indicate that variation may be a concern in radiation effects with the down scaling of feature size.

  15. Lightning-driven electric fields measured in the lower ionosphere: Implications for transient luminous events

    NASA Astrophysics Data System (ADS)

    Thomas, Jeremy N.; Barnum, Benjamin H.; Lay, Erin; Holzworth, Robert H.; Cho, Mengu; Kelley, Michael C.

    2008-12-01

    Transient luminous events above thunderstorms such as sprites, halos, and elves require large electric fields in the lower ionosphere. Yet very few in situ measurements in this region have been successfully accomplished, since it is typically too low in altitude for rockets and satellites and too high for balloons. In this article, we present some rare examples of lightning-driven electric field changes obtained at 75-130 km altitude during a sounding rocket flight from Wallops Island, Virginia, in 1995. We summarize these electric field changes and present a few detailed case studies. Our measurements are compared directly to a 2D numerical model of lightning-driven electromagnetic fields in the middle and upper atmosphere. We find that the in situ electric field changes are smaller than predicted by the model, and the amplitudes of these fields are insufficient for elve production when extrapolated to a 100 kA peak current stroke. This disagreement could be due to lightning-induced ionospheric conductivity enhancement, or it might be evidence of flaws in the electromagnetic pulse mechanism for elves.

  16. Consolidation of Complex Events via Reinstatement in Posterior Cingulate Cortex.

    PubMed

    Bird, Chris M; Keidel, James L; Ing, Leslie P; Horner, Aidan J; Burgess, Neil

    2015-10-28

    It is well-established that active rehearsal increases the efficacy of memory consolidation. It is also known that complex events are interpreted with reference to prior knowledge. However, comparatively little attention has been given to the neural underpinnings of these effects. In healthy adults humans, we investigated the impact of effortful, active rehearsal on memory for events by showing people several short video clips and then asking them to recall these clips, either aloud (Experiment 1) or silently while in an MRI scanner (Experiment 2). In both experiments, actively rehearsed clips were remembered in far greater detail than unrehearsed clips when tested a week later. In Experiment 1, highly similar descriptions of events were produced across retrieval trials, suggesting a degree of semanticization of the memories had taken place. In Experiment 2, spatial patterns of BOLD signal in medial temporal and posterior midline regions were correlated when encoding and rehearsing the same video. Moreover, the strength of this correlation in the posterior cingulate predicted the amount of information subsequently recalled. This is likely to reflect a strengthening of the representation of the video's content. We argue that these representations combine both new episodic information and stored semantic knowledge (or "schemas"). We therefore suggest that posterior midline structures aid consolidation by reinstating and strengthening the associations between episodic details and more generic schematic information. This leads to the creation of coherent memory representations of lifelike, complex events that are resistant to forgetting, but somewhat inflexible and semantic-like in nature. PMID:26511235

  17. Simulating an Extreme Wind Event in a Topographically Complex Region

    NASA Astrophysics Data System (ADS)

    Lennard, Christopher

    2014-07-01

    Complex topography modifies local weather characteristics such as air temperature, rainfall and airflow within a larger regional extent. The Cape Peninsula around Cape Town, South Africa, is a complex topographical feature responsible for the modification of rainfall and wind fields largely downstream of the Peninsula. During the passage of a cold front on 2 October 2002, an extreme wind event associated with tornado-like damage occurred in the suburb of Manenberg, however synoptic conditions did not indicate convective activity typically associated with a tornado. A numerical regional climate model was operated at very high horizontal resolution (500 m) to investigate the dynamics of the event. The model simulated an interaction between the topography of the peninsula and an airflow direction change associated with the passage of the cold front. A small region of cyclonic circulation was simulated over Manenberg that was embedded in an area of negative vorticity and a leeward gravity wave. The feature lasted 14 min and moved in a north to south direction. Vertically, it was not evident above 220 m. The model assessment describes this event as a shallow but intense cyclonic vortex generated in the lee of the peninsula through an interaction between the peninsula and a change in wind direction as the cold front made landfall. The model did not simulate wind speeds associated with the observed damage suggesting that the horizontal grid resolution ought to be at the scale of the event to more completely understand such microscale airflow phenomena.

  18. A pilot ASKAP survey of radio transient events in the region around the intermittent pulsar PSR J1107-5907

    NASA Astrophysics Data System (ADS)

    Hobbs, G.; Heywood, I.; Bell, M. E.; Kerr, M.; Rowlinson, A.; Johnston, S.; Shannon, R. M.; Voronkov, M. A.; Ward, C.; Banyer, J.; Hancock, P. J.; Murphy, Tara; Allison, J. R.; Amy, S. W.; Ball, L.; Bannister, K.; Bock, D. C.-J.; Brodrick, D.; Brothers, M.; Brown, A. J.; Bunton, J. D.; Chapman, J.; Chippendale, A. P.; Chung, Y.; DeBoer, D.; Diamond, P.; Edwards, P. G.; Ekers, R.; Ferris, R. H.; Forsyth, R.; Gough, R.; Grancea, A.; Gupta, N.; Harvey-Smith, L.; Hay, S.; Hayman, D. B.; Hotan, A. W.; Hoyle, S.; Humphreys, B.; Indermuehle, B.; Jacka, C. E.; Jackson, C. A.; Jackson, S.; Jeganathan, K.; Joseph, J.; Kendall, R.; Kiraly, D.; Koribalski, B.; Leach, M.; Lenc, E.; MacLeod, A.; Mader, S.; Marquarding, M.; Marvil, J.; McClure-Griffiths, N.; McConnell, D.; Mirtschin, P.; Neuhold, S.; Ng, A.; Norris, R. P.; O'Sullivan, J.; Pearce, S.; Phillips, C. J.; Popping, A.; Qiao, R. Y.; Reynolds, J. E.; Roberts, P.; Sault, R. J.; Schinckel, A. E. T.; Serra, P.; Shaw, R.; Shimwell, T. W.; Storey, M.; Sweetnam, A. W.; Tzioumis, A.; Westmeier, T.; Whiting, M.; Wilson, C. D.

    2016-03-01

    We use observations from the Boolardy Engineering Test Array (BETA) of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope to search for transient radio sources in the field around the intermittent pulsar PSR J1107-5907. The pulsar is thought to switch between an `off' state in which no emission is detectable, a weak state and a strong state. We ran three independent transient detection pipelines on two-minute snapshot images from a 13 h BETA observation in order to (1) study the emission from the pulsar, (2) search for other transient emission from elsewhere in the image and (3) to compare the results from the different transient detection pipelines. The pulsar was easily detected as a transient source and, over the course of the observations, it switched into the strong state three times giving a typical time-scale between the strong emission states of 3.7 h. After the first switch it remained in the strong state for almost 40 min. The other strong states lasted less than 4 min. The second state change was confirmed using observations with the Parkes radio telescope. No other transient events were found and we place constraints on the surface density of such events on these time-scales. The high sensitivity Parkes observations enabled us to detect individual bright pulses during the weak state and to study the strong state over a wide observing band. We conclude by showing that future transient surveys with ASKAP will have the potential to probe the intermittent pulsar population.

  19. Consolidation of Complex Events via Reinstatement in Posterior Cingulate Cortex

    PubMed Central

    Keidel, James L.; Ing, Leslie P.; Horner, Aidan J.

    2015-01-01

    It is well-established that active rehearsal increases the efficacy of memory consolidation. It is also known that complex events are interpreted with reference to prior knowledge. However, comparatively little attention has been given to the neural underpinnings of these effects. In healthy adults humans, we investigated the impact of effortful, active rehearsal on memory for events by showing people several short video clips and then asking them to recall these clips, either aloud (Experiment 1) or silently while in an MRI scanner (Experiment 2). In both experiments, actively rehearsed clips were remembered in far greater detail than unrehearsed clips when tested a week later. In Experiment 1, highly similar descriptions of events were produced across retrieval trials, suggesting a degree of semanticization of the memories had taken place. In Experiment 2, spatial patterns of BOLD signal in medial temporal and posterior midline regions were correlated when encoding and rehearsing the same video. Moreover, the strength of this correlation in the posterior cingulate predicted the amount of information subsequently recalled. This is likely to reflect a strengthening of the representation of the video's content. We argue that these representations combine both new episodic information and stored semantic knowledge (or “schemas”). We therefore suggest that posterior midline structures aid consolidation by reinstating and strengthening the associations between episodic details and more generic schematic information. This leads to the creation of coherent memory representations of lifelike, complex events that are resistant to forgetting, but somewhat inflexible and semantic-like in nature. SIGNIFICANCE STATEMENT Memories are strengthened via consolidation. We investigated memory for lifelike events using video clips and showed that rehearsing their content dramatically boosts memory consolidation. Using MRI scanning, we measured patterns of brain activity while

  20. An infrastructure for accurate characterization of single-event transients in digital circuits.

    PubMed

    Savulimedu Veeravalli, Varadan; Polzer, Thomas; Schmid, Ulrich; Steininger, Andreas; Hofbauer, Michael; Schweiger, Kurt; Dietrich, Horst; Schneider-Hornstein, Kerstin; Zimmermann, Horst; Voss, Kay-Obbe; Merk, Bruno; Hajek, Michael

    2013-11-01

    We present the architecture and a detailed pre-fabrication analysis of a digital measurement ASIC facilitating long-term irradiation experiments of basic asynchronous circuits, which also demonstrates the suitability of the general approach for obtaining accurate radiation failure models developed in our FATAL project. Our ASIC design combines radiation targets like Muller C-elements and elastic pipelines as well as standard combinational gates and flip-flops with an elaborate on-chip measurement infrastructure. Major architectural challenges result from the fact that the latter must operate reliably under the same radiation conditions the target circuits are exposed to, without wasting precious die area for a rad-hard design. A measurement architecture based on multiple non-rad-hard counters is used, which we show to be resilient against double faults, as well as many triple and even higher-multiplicity faults. The design evaluation is done by means of comprehensive fault injection experiments, which are based on detailed Spice models of the target circuits in conjunction with a standard double-exponential current injection model for single-event transients (SET). To be as accurate as possible, the parameters of this current model have been aligned with results obtained from 3D device simulation models, which have in turn been validated and calibrated using micro-beam radiation experiments at the GSI in Darmstadt, Germany. For the latter, target circuits instrumented with high-speed sense amplifiers have been used for analog SET recording. Together with a probabilistic analysis of the sustainable particle flow rates, based on a detailed area analysis and experimental cross-section data, we can conclude that the proposed architecture will indeed sustain significant target hit rates, without exceeding the resilience bound of the measurement infrastructure. PMID:24748694

  1. An infrastructure for accurate characterization of single-event transients in digital circuits☆

    PubMed Central

    Savulimedu Veeravalli, Varadan; Polzer, Thomas; Schmid, Ulrich; Steininger, Andreas; Hofbauer, Michael; Schweiger, Kurt; Dietrich, Horst; Schneider-Hornstein, Kerstin; Zimmermann, Horst; Voss, Kay-Obbe; Merk, Bruno; Hajek, Michael

    2013-01-01

    We present the architecture and a detailed pre-fabrication analysis of a digital measurement ASIC facilitating long-term irradiation experiments of basic asynchronous circuits, which also demonstrates the suitability of the general approach for obtaining accurate radiation failure models developed in our FATAL project. Our ASIC design combines radiation targets like Muller C-elements and elastic pipelines as well as standard combinational gates and flip-flops with an elaborate on-chip measurement infrastructure. Major architectural challenges result from the fact that the latter must operate reliably under the same radiation conditions the target circuits are exposed to, without wasting precious die area for a rad-hard design. A measurement architecture based on multiple non-rad-hard counters is used, which we show to be resilient against double faults, as well as many triple and even higher-multiplicity faults. The design evaluation is done by means of comprehensive fault injection experiments, which are based on detailed Spice models of the target circuits in conjunction with a standard double-exponential current injection model for single-event transients (SET). To be as accurate as possible, the parameters of this current model have been aligned with results obtained from 3D device simulation models, which have in turn been validated and calibrated using micro-beam radiation experiments at the GSI in Darmstadt, Germany. For the latter, target circuits instrumented with high-speed sense amplifiers have been used for analog SET recording. Together with a probabilistic analysis of the sustainable particle flow rates, based on a detailed area analysis and experimental cross-section data, we can conclude that the proposed architecture will indeed sustain significant target hit rates, without exceeding the resilience bound of the measurement infrastructure. PMID:24748694

  2. An estimate of the impact of transient luminous events on the atmospheric temperature

    NASA Astrophysics Data System (ADS)

    Arnone, E.; Berg, P.; Arnold, N. F.; Christiansen, B.; Thejll, P.

    2008-09-01

    We present an order of magnitude estimate of the impact of sprites and other transient luminous events (TLEs) on the atmospheric temperature via ozone changes. To address the effects of expected TLE-ozone changes of at most a few percent, we first study the linearity of the radiatively driven response of a stratosphere-mesosphere model and of a general circulation model (GCM) to a range of uniform climatological ozone perturbations. The study is limited to Northern Hemisphere winter conditions, when planetary wave activity is high and the non linear stratosphere-troposphere coupling can be strong. Throughout most of the middle atmosphere of both models, the radiatively driven temperature response to uniform 5% to 20% ozone perturbations shows a close-to linear relationship with the magnitude of the perturbation. A mid-latitude stratopause ozone perturbation is then imposed as an idealised experiment that mimics local temperature gradients introduced by the latitudinal dependence of TLEs. An unrealistically high 20% magnitude is adopted for the regional ozone perturbation to obtain statistical significance in the model response. The local linearity of the radiatively driven response is used to infer a first order estimate of TLE-induced temperature changes of the order of 0.015 K under typical conditions, and less than a peak temperature change of 0.3 K at 60 70 km height in coincidence of extraordinarily active TLE-producing thunderstorms before horizontal mixing quickly occurs. In the latter case, dedicated mesoscale modelling is needed to study the relevance of regional non linear processes which are expected to impact these radiatively driven responses.

  3. Transient Finite Element Analyses Developed to Model Fan Containment Impact Events

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael

    1997-01-01

    Research is underway to establish an increased level of confidence in existing numerical techniques for predicting transient behavior when the fan of a jet engine is released and impacts the fan containment system. To evaluate the predictive accuracy that can currently be obtained, researchers at the NASA Lewis Research Center used the DYNA 3D computer code to simulate large-scale subcomponent impact tests that were conducted at the University of Dayton Research Institute (UDRI) Impact Physics Lab. In these tests, 20- by 40-in. flat metal panels, contoured to the shape of a typical fan case, were impacted by the root section of a fan blade. The panels were oriented at an angle to the path of the projectile that would simulate the conditions in an actual blade-out event. The metal panels were modeled in DYNA 3D using a kinematic hardening model with the strain rate dependence of the yield stress governed by the Cowper-Simons rule. Failure was governed by the effective plastic strain criterion. The model of the fan blade and case just after impact is shown. By varying the maximum effective plastic strain, we obtained good qualitative agreement between the model and the experiments. Both the velocity required to penetrate the case and the deflection during impact compared well. This indicates that the failure criterion and constitutive model may be appropriate, but for DYNA 3D to be useful as a predictive tool, methods to determine accurate model parameters must be established. Simple methods for measuring model parameters are currently being developed. In addition, alternative constitutive models and failure criteria are being investigated.

  4. Radiation hardness evaluations of 65 nm fully depleted silicon on insulator and bulk processes by measuring single event transient pulse widths and single event upset rates

    NASA Astrophysics Data System (ADS)

    Furuta, Jun; Sonezaki, Eiji; Kobayashi, Kazutoshi

    2015-04-01

    We measure single event transient (SET) pulse widths on inverter chains and single event upset (SEU) rates on flip-flops (FFs) fabricated in 65 nm fully depleted silicon on insulator (FD-SOI) and bulk processes. The layout designs of test chips are strictly identical between their processes besides buried oxide (BOX) layers. Experimental results show that neutron-induced SEU and SET rates in the FD-SOI process are 230× and 450× lower than those in the bulk process, respectively.

  5. Transient Luminous Events and the 9 May 2007 Oklahoma Mesoscale Convective System

    NASA Astrophysics Data System (ADS)

    Lang, T. J.; Rutledge, S. A.; Lyons, W.; Cummer, S.; Meyer, J.; Holzworth, R.; Macgorman, D.

    2008-12-01

    On 9 May 2007 an asymmetric mesoscale convective system (MCS) passed through the domain of the Oklahoma Lightning Mapping Array while producing 26 transient luminous events (TLEs) in a 2-hour period, which were observed at the Yucca Ridge Field Station in northeastern Colorado. During the observation period (03-05 UTC), the MCS consisted of a short NW-SE-oriented line with a stratiform region to its north. This stratiform region also contained intense embedded convection, and rotated cyclonically as a mesoscale convective vortex. The MCS was dominated by negative cloud-to-ground (CG) lightning, with 95% of the 3037 detected National Lightning Detection Network (NLDN) strokes being negative, and total flash rate sometimes exceeded 100 flashes per minute. Twenty-four of the 26 TLEs observed in this case coincided with parent positive CG strokes detected by the NLDN (the other two likely were associated with undetected positive CGs). Eighteen of these events had valid impulse charge moment change (iCMC) retrievals by the National Charge Moment Change Network. Thirteen of these had iCMC values in excess of 100 C km, roughly consistent with past studies that suggest iCMC values ~100 C km or greater are favorable for generating TLEs. Fifty-eight percent of the TLE- producing positive CG strokes also were detected by the World Wide Lightning Location Network, which suggests that this global network may have promising utility in TLE research studies. Both convective regions (southern convective line, and embedded convection in the stratiform region) produced TLE parent flashes, although most TLE producers initiated in the stratiform-embedded convection. TLE parent flashes initiated around 5.7 km MSL in the embedded convection, but slightly higher (7.5 km) in the southern convective line. Both sets of TLE parent flashes tended to propagate near 6 km MSL in the stratiform region while producing their TLEs. In general, TLE flash altitudes were lower (by ~2 km or more) and

  6. Multi-Point Observations of Transient Phenomena at the Magnetopause Associated With Solar Wind Dynamic Pressure Impulse Events

    NASA Astrophysics Data System (ADS)

    Kim, H.; Clauer, C. R.; Lessard, M.; Engebretson, M. J.; Matzka, J.; Sibeck, D. G.; Singer, H. J.; Stolle, C.; Hartinger, M.; Weimer, D. R.; Xu, Z.

    2015-12-01

    We report multi-point conjugate observations of transient phenomena at the magnetopause using datasets from the Time History of Events and Macroscale Interactions during Substorms (THEMIS), Cluster, Geostationary Operational Environmental Satellite (GOES) spacecraft and interhemispheric ground magnetometer array. Simultaneous with the inward displacement of the magnetopause produced by an increase in solar wind dynamic pressure, we observe the generation of a pair of traveling convection vortices (TCVs) in both polar ionospheres. The TCV events are characterized by their single or twin vortex, of which the centers are located approximately at 72-76 degrees magnetic latitudes, propagating either dawnward or duskward away from local noon. ULF Pc1 waves identified as electromagnetic ion cyclotron (EMIC) waves in association with the initiation of the TCVs were also observed on the ground. It appears that the waves are generated by the increased instability caused by the compression of the magnetosphere during the transient events. We discuss the spatiotemporal structures of the transient phenomena near the magnetopause and their magnetospheric and ionospheric responses, concluding that the signatures are closely associated with the sudden increase of solar wind dynamic pressure.

  7. How the Structure of Mesoscale Precipitation Systems Affects their Production of Transient Luminous Events

    NASA Astrophysics Data System (ADS)

    Lang, T. J.; Lyons, W.; Rutledge, S. A.; Cummer, S. A.; MacGorman, D. R.

    2011-12-01

    Recently, Lang et al. (2010) analyzed the parent lightning of transient luminous events (TLEs) in the context of the structure and evolution of two mesoscale convective systems (MCSs). These two MCSs were very different - one a giant symmetric leading-line/trailing stratiform storm, and one a small asymmetric MCS that contained a mesoscale convective vortex. These structural differences were associated with substantially different TLE-parent lightning structure as well as TLE production. The results suggested that TLE (especially sprite) production, and TLE-parent positive charge altitude, depend on MCS morphology. Current work is focused on analyzing the structure, evolution, lightning behavior, and TLE production of additional MCSs over various regions of the United States. Several additional TLE-producing MCS cases already have been identified for the years 2008-2010, featuring a variety of organizational modes (symmetric, asymmetric, and other more exotic varieties) in different meteorological regimes (including some cold-season cases). More cases will be incorporated as they occur and are observed. Data sources include geostationary satellite imagery, Doppler radar, three-dimensional lightning mapping networks, ground-strike detection networks, charge moment change measurements, and low-light video observations. The ultimate goal is to further test the hypothesis that MCS structure affects TLE production, and if so to quantify its impact. Research on two Oklahoma case studies, a multicellular system that occurred on 24 March 2009 and a classic bow-echo MCS that occurred on 19 August 2009, is ongoing. Over a 2.5-h period, the March case produced 23 observed TLEs (all sprites) whose parent flashes occurred within 175 km of the Oklahoma Lightning Mapping Array (OKLMA). The median altitude of LMA sources during the TLEs was 5.9 km above Mean Sea Level (MSL), or -19.2 °C. The August storm produced, in 2.5 hours, 34 TLEs (all sprites) with 32 of those having parent

  8. Imaging Parameters and Recurrent Cerebrovascular Events in Patients With Minor Stroke or Transient Ischemic Attack

    PubMed Central

    Yaghi, Shadi; Rostanski, Sara K.; Boehme, Amelia K.; Martin-Schild, Sheryl; Samai, Alyana; Silver, Brian; Blum, Christina A.; Jayaraman, Mahesh V.; Siket, Matthew S.; Khan, Muhib; Furie, Karen L.; Elkind, Mitchell S. V.; Marshall, Randolph S.; Willey, Joshua Z.

    2016-01-01

    IMPORTANCE Neurological worsening and recurrent stroke contribute substantially to morbidity associated with transient ischemic attacks and strokes (TIA-S). OBJECTIVE To determine predictors of early recurrent cerebrovascular events (RCVEs) among patients with TIA-S and National Institutes of Health Stroke Scale scores of 0 to 3. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort study was conducted at 2 tertiary care centers (Columbia University Medical Center, New York, New York, and Tulane University Medical Center, New Orleans, Louisiana) between January 1, 2010, and December 31, 2014. All patients with neurologist-diagnosed TIA-S with a National Institutes of Health Stroke Scale score of 0 to 3 who presented to the emergency department were included. MAIN OUTCOMES AND MEASURES The primary outcome (adjudicated by 3 vascular neurologists) was RCVE: neurological deterioration in the absence of a medical explanation or recurrent TIA-S during hospitalization. RESULTS Of the 1258 total patients, 1187 had no RCVEs and 71 had RCVEs; of this group, 750 patients (63.2%) and 39 patients (54.9%), respectively, were aged 60 years or older. There were 505 patients with TIA-S at Columbia University; 31 (6.1%) had RCVEs (15 patients had neurological deterioration only, 11 had recurrent TIA-S only, and 5 had both). The validation cohort at Tulane University consisted of 753 patients; 40 (5.3%) had RCVEs (24 patients had neurological deterioration only and 16 had both). Predictors of RCVE in multivariate models in both cohorts were infarct on neuroimaging (computed tomographic scan or diffusion-weighted imaging sequences on magnetic resonance imaging) (Columbia University: not applicable and Tulane University: odds ratio, 1.75; 95% CI, 0.82–3.74; P = .15) and large-vessel disease etiology (Columbia University: odds ratio, 6.69; 95% CI, 3.10–14.50 and Tulane University: odds ratio, 8.13; 95% CI, 3.86–17.12; P < .001). There was an increase in the percentage of

  9. Transient Luminous Events: optical emissions from high altitudes to probe the Earth's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Luque, A.; Gordillo-Vázquez, F. J.

    2012-04-01

    Transient Luminous Events are short but intense optical emissions from the upper terrestrial atmosphere, driven by the electric fields generated by a tropospheric electric storm. They were first observed in 1989 [1] but they had been predicted by C.T.R. Wilson already in 1925 [2]. Wilson argued that the electric field needed to initiate a discharge (the breakdown field) is proportional to the atmospheric density and therefore decreases exponentially with altitude; meanwhile the electric field created by a charged cloud is roughly dipolar and decays slower. Therefore there exists an altitude where the cloud field surpasses the breakdown field and an electric discharge is initiated. The combination of modeling and observations of TLEs allows us to quantify their influence in the global atmospheric chemistry and the global electric circuit that connects the surface of the Earth with the ionosphere. But, equally importantly, TLEs serve as natural probes to remotely investigate the atmosphere that surrounds them. In this talk we will survey some recent results on the modelling of TLEs. 1. Sprite beads provide an example of a possible use of TLEs to remotely probe the Earth's mesosphere. Sprites are filamentary discharges, some tens of kilometers wide, appearing at altitudes from about 50 to about 85 km. Sometimes, in the wake of a sprite, luminous spots (beads) persist much longer than the main emissions. These sprite beads reveal underlying inhomogeneities in the atmospheric conductivity [4] whose precise origin is still uncertain. 2. Another path to investigate the mesosphere through TLE observations is to compare observed spectra with kinetic models [5] combined with electrodynamic simulations [6]. For that purpose, we have modeled emissions from terrestrial TLEs: we calculated the expected emissions in the ultraviolet (Lyman-Birge-Hopfield band of molecular nitrogen), in the near UV and visible blue (second positive system of N2) and in the red and near infrared

  10. A study of the nature of lightning that produces transient luminous events such as sprites

    NASA Astrophysics Data System (ADS)

    Lang, T. J.; Cummer, S. A.; Lyons, W. A.; Rutledge, S. A.; Li, J.

    2010-12-01

    Continuing research on transient luminous events (TLEs) above two mesoscale convective systems (MCSs) in range of the Oklahoma Lightning Mapping Array (LMA) is discussed. The 20 June 2007 MCS was a massive leading-line/trailing-stratiform storm that produced 282 observed TLEs over a 4-h period, while the 9 May 2007 storm was an asymmetric MCS that produced 25 confirmed TLEs during a 2-h period. Interestingly, despite the smaller number the 9 May storm was a more efficient producer of TLEs (which were mainly sprites in both storms), as 13.7% of positive cloud-to-ground (+CG) strokes were associated with TLEs, compared to only 3.6% of +CGs on 20 June. However, 20 June TLE-parent +CGs discharged electrical layers that were 37% higher in altitude than on 9 May, suggesting that total charge moment changes (charge times altitude; CMC) for +CG strokes on 20 June should have been higher for a given amount of charge. As large CMC values have been implicated in the production of TLEs such as sprites, one possibility is that 20 June +CGs neutralized less charge on average than 9 May, thereby reducing total CMC values despite the altitude advantage on 20 June. This hypothesis is examined via analysis of total CMC retrievals on TLE-producing flashes from both storms. As part of this work, flash volumes will be estimated using LMA data, and approximate charge densities in flashing regions will be retrieved. Also, analysis of CMC data from energetic but non-TLE-producing +CG strokes on 20 June will be presented, and contrasted with that of TLE-parent strokes. Approximate azimuths to TLEs from the video cameras trained on these storms will be exploited to estimate spatial offsets between parent lightning and TLE positions. Analyses from other cases over the Oklahoma LMA, from 2008-10, will be contrasted to the 2007 cases, if possible. The ultimate goal of this work is to better understand the nature of TLE-parent lightning - what distinguishes it from lightning that produces no

  11. Comparison of Single Event Transients Generated by Short Pulsed X-Rays, Lasers and Heavy Ions

    SciTech Connect

    Cardoza, David; LaLumondiere, Stephen D.; Tockstein, Michael A.; Brewe, Dale L.; Wells, Nathan P.; Koga, Rokutaro; Gaab, K. M.; Lotshaw, William T.; Moss, Steven C.

    2014-12-01

    We report an experimental study of the transients generated by pulsed x-rays, heavy ions, and different laser wavelengths in a Si p-i-n photodiode. We compare the charge collected by all of the excitation methods to determine the equivalent LET for pulsed x-rays relative to heavy ions. Our comparisons show that pulsed x-rays from synchrotron sources can generate a large range of equivalent LET and generate transients similar to those excited by laser pulses and heavy ion strikes. We also look at how the pulse width of the transients changes for the different excitation methods. We show that the charge collected with pulsed x-rays is greater than expected as the x-ray photon energy increases. Combined with their capability of focusing to small spot sizes and of penetrating metallization, pulsed x-rays are a promising new tool for high resolution screening of SEE susceptibility

  12. A new software on TUG-T60 autonomous telescope for astronomical transient events

    NASA Astrophysics Data System (ADS)

    Dindar, Murat; Helhel, Selçuk; Esenoğlu, Hasan; Parmaksızoğlu, Murat

    2015-03-01

    Robotic telescopes usually run under the control of a scheduler, which provides high-level control by selecting astronomical targets for observation. TÜBİTAK (Scientific and Technological Research Council of Turkey) National Observatory (TUG)-T60 Robotic Telescope is controlled by open-source OCAAS software, formally named Talon. This study introduces new software which was designed for Talon to catch GRB, GAIA and transient alerts. The new GRB software module (daemon process) alertd is running with all other modules of Talon such as telescoped; focus, dome; camerad and telrun. Maximum slew velocity and acceleration limits of the T60 telescope are enough fast for the GRB and transient observations.

  13. NMR analysis of the transient complex between membrane photosystem I and soluble cytochrome c6.

    PubMed

    Díaz-Moreno, Irene; Díaz-Quintana, Antonio; Molina-Heredia, Fernando P; Nieto, Pedro M; Hansson, Orjan; De la Rosa, Miguel A; Karlsson, B Göran

    2005-03-01

    A structural analysis of the surface areas of cytochrome c(6), responsible for the transient interaction with photosystem I, was performed by NMR transverse relaxation-optimized spectroscopy. The hemeprotein was titrated by adding increasing amounts of the chlorophyllic photosystem, and the NMR spectra of the free and bound protein were analyzed in a comparative way. The NMR signals of cytochrome c(6) residues located at the hydrophobic and electrostatic patches, which both surround the heme cleft, were specifically modified by binding. The backbones of internal residues close to the hydrophobic patch of cytochrome c(6) were also affected, a fact that is ascribed to the conformational changes taking place inside the hemeprotein when interacting with photosystem I. To the best of our knowledge, this is the first structural analysis by NMR spectroscopy of a transient complex between soluble and membrane proteins. PMID:15611120

  14. The Diagnostic Potential of Transition Region Lines Undergoing Transient Ionization in Dynamic Events

    NASA Astrophysics Data System (ADS)

    Doyle, J. G.; Giunta, A.; Singh, A.; Madjarska, M. S.; Summers, H.; Kellett, B. J.; O'Mullane, M.

    2012-09-01

    We discuss the diagnostic potential of high cadence UV spectral data when transient ionization is considered. For this we use high cadence UV spectra taken during the impulsive phase of a solar flare (observed with instruments on-board the Solar Maximum Mission) which showed excellent correspondence with hard X-ray pulses. The ionization fraction of the transition region ion O v and, in particular, the contribution function for the O v 1371 Å line are computed within the Atomic Data and Analysis Structure, which is a collection of fundamental and derived atomic data and codes to manipulate them. Due to transient ionization, the O v 1371 Å line is enhanced in the first fraction of a second with the peak in the line contribution function occurring initially at a higher electron temperature than in ionization equilibrium. The rise time and enhancement factor depend mostly on the electron density. The fractional increase in the O v 1371 Å emissivity due to transient ionization can reach a factor of two-four and can explain the fast response in the line flux of transition regions ions during the impulsive phase of flares solely as a result of transient ionization. This technique can be used to diagnose the electron temperature and density of solar flares observed with the forthcoming Interface Region Imaging Spectrograph.

  15. Transient extracellular glutamate events in the basolateral amygdala track reward seeking actions

    PubMed Central

    Wassum, KM; Tolosa, VM; Tseng, TC; Balleine, BW; Monbouquette, HG; Maidment, NT

    2012-01-01

    The ability to make rapid, informed decisions about whether or not to engage in a sequence of actions to earn reward is essential for survival. Modeling in rodents has demonstrated a critical role for the basolateral amygdala (BLA) in such reward-seeking actions, but the precise neurochemical underpinnings are not well understood. Taking advantage of recent advancements in biosensor technologies, we made spatially discrete near-real time extracellular recordings of the major excitatory transmitter, glutamate, in the BLA of rats performing a self-paced lever-pressing sequence task for sucrose reward. This allowed us to detect rapid transient fluctuations in extracellular BLA glutamate time-locked to action performance. These glutamate transients tended to precede lever pressing actions and were markedly increased in frequency when rats were engaged in such reward seeking actions. Based on muscimol and tetrodotoxin microinfusions these glutamate transients appeared to originate from the terminals of neurons with cell bodies in the orbital frontal cortex. Importantly, glutamate transient amplitude and frequency fluctuated with the value of the earned reward and positively predicted lever pressing rate. Such novel rapid glutamate recordings during instrumental performance identify a role for glutamatergic signaling within the BLA in instrumental reward-seeking actions. PMID:22357857

  16. Transient crustal movement in the northern Izu-Bonin arc starting in 2004: A large slow slip event or a slow back-arc rifting event?

    NASA Astrophysics Data System (ADS)

    Arisa, Deasy; Heki, Kosuke

    2016-07-01

    The Izu-Bonin arc lies along the convergent boundary where the Pacific Plate subducts beneath the Philippine Sea Plate. Horizontal velocities of continuous Global Navigation Satellite System stations on the Izu Islands move eastward by up to ~ 1 cm/year relative to the stable part of the Philippine Sea Plate suggesting active back-arc rifting behind the northern part of the arc. Here, we report that such eastward movements transiently accelerated in the middle of 2004 resulting in ~ 3 cm extra movements in 3 years. We compare three different mechanisms possibly responsible for this transient movement, i.e. (1) postseismic movement of the 2004 September earthquake sequence off the Kii Peninsula far to the west, (2) a temporary activation of the back-arc rifting to the west dynamically triggered by seismic waves from a nearby earthquake, and (3) a large slow slip event in the Izu-Bonin Trench to the east. By comparing crustal movements in different regions, the first possibility can be shown unlikely. It is difficult to rule out the second possibility, but current evidence support the third possibility, i.e. a large slow slip event with moment magnitude of ~ 7.5 may have occurred there.

  17. Transient structures of the human fetal brain: subplate, thalamic reticular complex, ganglionic eminence.

    PubMed

    Ulfig, N; Neudörfer, F; Bohl, J

    2000-07-01

    Morphological features of the subplate, the thalamic reticular complex and the ganglionic eminence, which represent three major transient structures of the human fetal forebrain, are summarized with special reference to their functional roles. The subplate harboring various neuronal types is an outstandingly wide zone subjacent to the cortical plate in the human fetal brain. Within the subplate various cortical afferents establish synaptic contacts for a prolonged period before entering the cortical plate. Therefore, the subplate is regarded as a "waiting compartment" which is required for the formation of mature cortical connections. Next to the thalamic reticular nucleus, within the fibers of internal capsule, the perireticular nucleus is located which has been established as a distinct entity during development. Its various neuronal types express a number of different neuroactive substances. Perinatally, the perireticular nucleus is drastically reduced in size. It is involved in the guidance of corticofugal and thalamocortical fibers. The ganglionic eminence is a conspicuous proliferative area that persists throughout nearly the entire fetal period. In the human fetal brain it extends medially upon the dorsal thalamic nuclei which receive precursor cells from the ganglionic eminence. Postmitotic cells in the marginal zone of the ganglionic eminence serve as an intermediate target for growing axons. On the whole, all three structures establish transient neural circuitries that may be essential for the formation of adult projections. The characteristics of the three transient structures are particularly relevant for developmental neuropathology as these structures may be damaged in disorders that preferentially occur in preterm infants. PMID:10963122

  18. Modeling from Local to Subsystem Level Effects in Analog and Digital Circuits Due to Space Induced Single Event Transients

    NASA Technical Reports Server (NTRS)

    Perez, Reinaldo J.

    2011-01-01

    Single Event Transients in analog and digital electronics from space generated high energetic nuclear particles can disrupt either temporarily and sometimes permanently the functionality and performance of electronics in space vehicles. This work first provides some insights into the modeling of SET in electronic circuits that can be used in SPICE-like simulators. The work is then directed to present methodologies, one of which was developed by this author, for the assessment of SET at different levels of integration in electronics, from the circuit level to the subsystem level.

  19. Single Event Transient Analysis of an SOI Operational Amplifier for Use in Low-Temperature Martian Exploration

    NASA Technical Reports Server (NTRS)

    Laird, Jamie S.; Scheik, Leif; Vizkelethy, Gyorgy; Mojarradi, Mohammad M; Chen, Yuan; Miyahira, Tetsuo; Blalock, Benjamin; Greenwell, Robert; Doyle, Barney

    2006-01-01

    The next generation of Martian rover#s to be launched by JPL are to examine polar regions where temperatures are extremely low and the absence of an earth-like atmosphere results in high levels of cosmic radiation at ground level. Cosmic rays lead to a plethora of radiation effects including Single Event Transients (SET) which can severely degrade microelectronic functionality. As such, a radiation-hardened, temperature compensated CMOS Single-On-Insulator (SOI) Operational Amplifier has been designed for JPL by the University of Tennessee and fabricated by Honeywell using the SOI V process. SOI technology has been shownto be far less sensitive to transient effects than both bulk and epilayer Si. Broad beam heavy-ion tests at the University of Texas A&M using Kr and Xebeams of energy 25MeV/amu were performed to ascertain the duration and severity of the SET for the op-amp configured for a low and high gain application. However, some ambiguity regarding the location of transient formation required the use of a focused MeV ion microbeam. A 36MeV O6(+) microbeam. the Sandia National Laboratory (SNL) was used to image and verify regions of particular concern. This is a viewgraph presentation

  20. Transient surface modifications during singular heating events at diode laser facets

    NASA Astrophysics Data System (ADS)

    Hempel, Martin; Tomm, Jens W.; Bachmann, Alexander; Lauer, Christian; Furitsch, Michael; Strauß, Uwe; Elsaesser, Thomas

    2016-05-01

    Surface morphology changes and transient reflectance changes at diode laser facets are monitored during the catastrophic optical damage (COD) process in a single pulse operation. Time-resolved micro-reflectance spectroscopy with a streak-camera (time resolution ˜20 ns) allows us to observe the creation sequence of up to four distinct degradation seed points at a device facet within <300 ns. The shape of the COD seeds is created within <30-40 ns. Creation of non-planar facet areas by local melting represents the main mechanism behind the observed reflectivity changes. Subsequently the surface temperature decreases within the pulse which caused the COD.

  1. High-Speed Single-Event Current Transient Measurements in SiGe HBTs

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Reed, R.A.; McMorrow, D.; Vizkelethy, G.; Ferlet-Cavrois, V.; Baggio, J.; Paillet, P.; Duhamel, O.; Phillips, S.D.; Sutton, A.K.; Diestelhorst, R.M.; Cressler, J.D.; Dodd, P.E.; Pate, N.D.; Alles, M.L.; Schrimpf, R.D.; Marshall, P.W.; LaBel, K.A.

    2009-01-01

    Time-resolved ion beam induced charge reveals heavy ion response of IBM 5AM SiGe HBT: 1) Position correlation. 2) Unique response for different bias schemes. 3) Similarities to TPA pulsed-laser data. Heavy ion broad-beam transients provide more realistic device response: 1) Feedback using microbeam data 2) Overcome existing issues of LET and ion range with microbeam Both micro- and broad-beam data sets yield valuable input for TCAD simulations. Uncover detailed mechanisms for SiGe HBTs and other devices fabricated on lightly-doped substrates.

  2. A transient event in AD 775 reported by al-Tabarı: A bolide - not a nova, supernova, or kilonova

    NASA Astrophysics Data System (ADS)

    Neuhäuser, R.; Kunitzsch, P.

    2014-11-01

    Given that the cause for the strong increase in 14C in AD 774/5 in Japanese and German trees is still a matter of debate (e.g. short gamma-ray burst or solar super-flare), we have searched in Arabic chronicles for reports about unusual transient celestial events. In the History of al-Tabarı we found two (almost identical) reports about such an event. The group around caliph al-Mansūr observed a transient event while on the way from Baghdad to Mecca on AD 775 Augusst 29 - September 1 (Julian calendar). A celestial object (kawkab) was seen to fall or set (inqadda), and its trace (atharuhu) was seen for at least tens of minutes (up to 70-90 min) during morning twilight. The reports use the Arabic words kawkab and athar(uhu), which were also used in the known Arabic reports about supernovae SN 1006 and 1054, so that one might consider an interpretation as a nova-like event. The kawkab (celestial object) was observed only during the morning twilight at a brightness of probably between about -3 and 0 mag. Such a brightness and time-scale would be expected for optical kilonovae (at {˜ 3} to 9 kpc) in the context of short gamma-ray bursts. There are no similar reports from eastern Asia for this time. However, the short reports are fully consistent with a bolide: The word kawkab can be used for meteor, the verb inqadda normally means falling down, the word atharuhu can mean its trace. We therefore prefer the interpretation as bolide. We discuss in detail how to convert the Muslim calendar date to a date in the Julian calendar using first the calculated Islamic calendar and then considering the time when the crescent new moon could be visible at the given location.

  3. Characterization of lightning with ISUAL data in order to identify the Transient Luminous Events for the future TARANIS mission

    NASA Astrophysics Data System (ADS)

    Offroy, Marc; Farges, Thomas; Kuo, Cheng-Ling; Bing-Chih Chen, Alfred; Hsu, Rue-Ron; Su, Han-Tzong; Takahashi, Yukihiro; Mende, Stephen B.; Frey, Harald U.

    2014-05-01

    The main objective of the TARANIS (Tool for the Analysis of RAdiation from ligntNing and Sprites) satellite is to understand transient event energetic mechanisms that generate transient luminous emissions (TLEs) and gamma ray flashes (TGFs) in the terrestrial atmosphere above thunderstorm areas. These emissions are a manifestation of a coupling between atmosphere, ionosphere and magnetosphere. However, as the TARANIS microsatellite will observe from nadir, TLE identification is not easy using only images because TLEs and lightning are superposed. On board triggering using photometers is set up to further TLEs recording. It is necessary to take into account the temporal and spectral characteristics of lightning and TLEs. For this purpose, a dataset from a previous space mission called ISUAL is used. ISUAL is dedicated to the study of sprites from limb observation on the FORMOSAT-2 satellite. We have access to photometric and also imaging data. A database only dedicated on lightning was made. Several information was identified, such as the photometric responses, the number of photons emitted or the duration of different events analyzed. The main objective of the presented work is to show that a better knowledge about lightning signal is an asset for TLEs recognition.

  4. Transient, reversible apnoea following ablation of the pre-Bötzinger complex in rats

    PubMed Central

    St-Jacques, René; St-John, Walter M

    1999-01-01

    In some anaesthetized preparations, eupnoea is eliminated following a blockade or destruction of neurons in a rostral medullary pre-Bötzinger complex.Neurons in this region might underlie the neurogenesis of eupnoea, or be the source of an input which is necessary for eupnoea to be expressed. If the latter, any apnoea following ablation of the pre-Bötzinger complex might be reversed by an augmentation in ‘tonic input.’ Contrariwise, this apnoea should be permanent if the neuronal activities of the pre- Bötzinger complex are an exclusive generator of the eupnoeic rhythm.Decerebrate, vagotomized, paralysed and ventilated adult rats were studied. Efferent activity of the phrenic nerve was recorded as an index of ventilatory activity.Blockade or destruction of neuronal activities of the pre-Bötzinger complex by unilateral and/or bilateral injections of muscimol or kainic acid eliminated eupnoea only transiently. Eupnoea returned following activation of the peripheral chemoreceptors and spontaneously over time.Results do not support the concept that neuronal activities of the pre-Bötzinger complex play an exclusive role in the neurogenesis of eupnoea in vivo. Rather, these neuronal activities appear to provide a tonic input to the ponto-medullary circuit which generates eupnoea and/or appear to be one component of this circuit. PMID:10517821

  5. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    SciTech Connect

    Black, Dolores A.; Robinson, William H.; Limbrick, Daniel B.; Black, Jeffrey D.; Wilcox, Ian Z.

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. An accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventional model based on one double-exponential source can be incomplete. A small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. Furthermore, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.

  6. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    DOE PAGESBeta

    Black, Dolores A.; Robinson, William H.; Limbrick, Daniel B.; Black, Jeffrey D.; Wilcox, Ian Z.

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. An accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventional modelmore » based on one double-exponential source can be incomplete. A small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. Furthermore, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.« less

  7. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    SciTech Connect

    Black, Dolores Archuleta; Robinson, William H.; Wilcox, Ian Zachary; Limbrick, Daniel B.; Black, Jeffrey D.

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. Likewise, an accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventional model based on one double-exponential source can be incomplete. Furthermore, a small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. As a result, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.

  8. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    DOE PAGESBeta

    Black, Dolores Archuleta; Robinson, William H.; Wilcox, Ian Zachary; Limbrick, Daniel B.; Black, Jeffrey D.

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. Likewise, an accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventionalmore » model based on one double-exponential source can be incomplete. Furthermore, a small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. As a result, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.« less

  9. Crystal structures of the HypCD complex and the HypCDE ternary complex: transient intermediate complexes during [NiFe] hydrogenase maturation.

    PubMed

    Watanabe, Satoshi; Matsumi, Rie; Atomi, Haruyuki; Imanaka, Tadayuki; Miki, Kunio

    2012-12-01

    [NiFe] hydrogenase maturation represents one of the most dynamic and sophisticated processes in metallocenter assembly. The Fe(CN)(2)CO moiety of [NiFe] hydrogenases is assembled via unknown transient interactions among specific maturation proteins HypC (metallochaperone), HypD (redox protein), and HypE (cyanide synthesis/donor). Here, we report the structures of the HypC-HypD and HypC-HypD-HypE complexes, providing a view of the transient interactions that take place during the maturation process. HypC binds to the conserved region of HypD through extensive hydrophobic interactions. The ternary complex formation between HypE and the HypCD complex involves both HypC and HypD, rendering the HypE conformation favorable for cyanide transfer. In the complex, the conserved cysteines of HypC and HypD form an Fe binding site. The conserved C-terminal cysteine of HypE can access the thiol redox cascade of HypD. These results provide structural insights into the Fe atom cyanation in the HypCDE complex. PMID:23123111

  10. Complex Dynamic Scene Perception: Effects of Attentional Set on Perceiving Single and Multiple Event Types

    ERIC Educational Resources Information Center

    Sanocki, Thomas; Sulman, Noah

    2013-01-01

    Three experiments measured the efficiency of monitoring complex scenes composed of changing objects, or events. All events lasted about 4 s, but in a given block of trials, could be of a single type (single task) or of multiple types (multitask, with a total of four event types). Overall accuracy of detecting target events amid distractors was…

  11. Sound Exposure Calculations for Transient Events and Other Improvements to an Acoustical Tactical Decision Aid

    NASA Astrophysics Data System (ADS)

    Wilson, D. K.; Nguyen, V. A.; Srour, Nassy; Noble, John

    2002-08-01

    Recent enhancements to an acoustical tactical decision aid, called the Acoustic Battlefield Aid (ABFA), are described. ABFA predicts the effects of the atmosphere and local terrain on the performance of acoustical sensors, using advanced sound propagation models. Among the enhancements are: (1) sound-exposure and detection calculations for moving and transient sources, (2) new display capabilities including loading of vector-map features from CDs, (3) an interactive menu for entering and managing acoustical and meteorological ground properties, (4) initialization of runs from field trials stored in the U.S. Army Research Laboratory's Automatic Target Recognition Acoustic Database, (5) a Java-based interface to numerical weather forecast data over the Internet, and (6) creation of a Windows executable version using the MATLAB compiler.

  12. Potential of mean force and transient states in polyelectrolyte pair complexation

    NASA Astrophysics Data System (ADS)

    Xu, Xiao; Kanduč, Matej; Wu, Jianzhong; Dzubiella, Joachim

    2016-07-01

    The pair association between two polyelectrolytes (PEs) of the same size but opposite charge is systematically studied in terms of the potential of mean force (PMF) along their center-of-mass reaction coordinate via coarse-grained, implicit-solvent, explicit-salt computer simulations. The focus is set on the onset and the intermediate transient stages of complexation. At conditions above the counterion-condensation threshold, the PE association process exhibits a distinct sliding-rod-like behavior where the polymer chains approach each other by first stretching out at a critical distance close to their contour length, then "shaking hand" and sliding along each other in a parallel fashion, before eventually folding into a neutral complex. The essential part of the PMF for highly charged PEs can be very well described by a simple theory based on sliding charged "Debye-Hückel" rods with renormalized charges in addition to an explicit entropy contribution owing to the release of condensed counterions. Interestingly, at the onset of complex formation, the mean force between the PE chains is found to be discontinuous, reflecting a bimodal structural behavior that arises from the coexistence of interconnected-rod and isolated-coil states. These two microstates of the PE complex are balanced by subtle counterion release effects and separated by a free-energy barrier due to unfavorable stretching entropy.

  13. Potential of mean force and transient states in polyelectrolyte pair complexation.

    PubMed

    Xu, Xiao; Kanduč, Matej; Wu, Jianzhong; Dzubiella, Joachim

    2016-07-21

    The pair association between two polyelectrolytes (PEs) of the same size but opposite charge is systematically studied in terms of the potential of mean force (PMF) along their center-of-mass reaction coordinate via coarse-grained, implicit-solvent, explicit-salt computer simulations. The focus is set on the onset and the intermediate transient stages of complexation. At conditions above the counterion-condensation threshold, the PE association process exhibits a distinct sliding-rod-like behavior where the polymer chains approach each other by first stretching out at a critical distance close to their contour length, then "shaking hand" and sliding along each other in a parallel fashion, before eventually folding into a neutral complex. The essential part of the PMF for highly charged PEs can be very well described by a simple theory based on sliding charged "Debye-Hückel" rods with renormalized charges in addition to an explicit entropy contribution owing to the release of condensed counterions. Interestingly, at the onset of complex formation, the mean force between the PE chains is found to be discontinuous, reflecting a bimodal structural behavior that arises from the coexistence of interconnected-rod and isolated-coil states. These two microstates of the PE complex are balanced by subtle counterion release effects and separated by a free-energy barrier due to unfavorable stretching entropy. PMID:27448900

  14. Sex Differences in Infants' Ability to Represent Complex Event Sequences

    ERIC Educational Resources Information Center

    Schweinle, Amy; Wilcox, Teresa

    2004-01-01

    Prior research suggests that when very simple event sequences are used, 4.5-month-olds demonstrate the ability to individuate objects based on the continuity or disruption of their speed of motion (Wilcox & Schweinle, 2003). However, infants demonstrate their ability to individuate objects in an event-monitoring task (i.e., infants must keep track…

  15. Using the concept of transient complex for affinity predictions in CAPRI rounds 20-27 and beyond.

    PubMed

    Qin, Sanbo; Zhou, Huan-Xiang

    2013-12-01

    Predictions of protein-protein binders and binding affinities have traditionally focused on features pertaining to the native complexes. In developing a computational method for predicting protein-protein association rate constants, we introduced the concept of transient complex after mapping the interaction energy surface. The transient complex is located at the outer boundary of the bound-state energy well, having near-native separation and relative orientation between the subunits but not yet formed most of the short-range native interactions. We found that the width of the binding funnel and the electrostatic interaction energy of the transient complex are among the features predictive of binders and binding affinities. These ideas were very promising for the five affinity-related targets (T43-45, 55, and 56) of CAPRI rounds 20-27. For T43, we ranked the single crystallographic complex as number 1 and were one of only two groups that clearly identified that complex as a true binder; for T44, we ranked the only design with measurable binding affinity as number 4. For the nine docking targets, continuing on our success in previous CAPRI rounds, we produced 10 medium-quality models for T47 and acceptable models for T48 and T49. We conclude that the interaction energy landscape and the transient complex in particular will complement existing features in leading to better prediction of binding affinities. PMID:23873496

  16. Transient cerebral hypoperfusion and hypertensive events during atrial fibrillation: a plausible mechanism for cognitive impairment

    PubMed Central

    Anselmino, Matteo; Scarsoglio, Stefania; Saglietto, Andrea; Gaita, Fiorenzo; Ridolfi, Luca

    2016-01-01

    Atrial fibrillation (AF) is associated with an increased risk of dementia and cognitive decline, independent of strokes. Several mechanisms have been proposed to explain this association, but altered cerebral blood flow dynamics during AF has been poorly investigated: in particular, it is unknown how AF influences hemodynamic parameters of the distal cerebral circulation, at the arteriolar and capillary level. Two coupled lumped-parameter models (systemic and cerebrovascular circulations, respectively) were here used to simulate sinus rhythm (SR) and AF. For each simulation 5000 cardiac cycles were analyzed and cerebral hemodynamic parameters were calculated. With respect to SR, AF triggered a higher variability of the cerebral hemodynamic variables which increases proceeding towards the distal circulation, reaching the maximum extent at the arteriolar and capillary levels. This variability led to critical cerebral hemodynamic events of excessive pressure or reduced blood flow: 303 hypoperfusions occurred at the arteriolar level, while 387 hypertensive events occurred at the capillary level during AF. By contrast, neither hypoperfusions nor hypertensive events occurred during SR. Thus, the impact of AF per se on cerebral hemodynamics candidates as a relevant mechanism into the genesis of AF-related cognitive impairment/dementia. PMID:27334559

  17. Suppression of Transient Events by Levitation (STABLE): Results From the USML-2 Mission. Experiment 38

    NASA Technical Reports Server (NTRS)

    Nurre, Gerald S.; Edberg, Donald L.

    1998-01-01

    Microgravity science payloads can be extremely sensitive to vibrations from machinery, acoustics, ventilation, and crew activity. Suppression of Transient Acceleration by Levitation (STABLE) is an active vibration isolation system designed to protect payloads from these disturbances. This paper gives an account of results from the flight demonstration of the STABLE microgravity isolation system, which was developed and successfully flight tested in orbit during USML-2, with the participation of Astronaut Fred Leslie. Following a very brief description of the operational principles, the hardware and software design, and performance criteria, results of the analysis of measured flight data are presented to provide an evaluation of system performance parameters, including acceleration attenuation, assessment of sway space, system power consumption, and other factors critical to the performance of an isolation system. Lessons learned and potential design improvements and evolutions are discussed. Data reduction by Robert Boucher of McDonnell Douglas Aerospace (MDA) was substantially assisted by Kenneth Hrovat of Tal-Cut, Inc., under support from National Aeronautics and Space Administration/Lewis Research Center (LeRC), Cleveland, OH.

  18. CH Bond Activation of Methane by a Transient η(2)-Cyclopropene/Metallabicyclobutane Complex of Niobium.

    PubMed

    Li, Chen; Dinoi, Chiara; Coppel, Yannick; Etienne, Michel

    2015-10-01

    This study challenges the problem of the activation of a CH bond of methane by soluble transition metal complexes. High pressure solution NMR, isotopic labeling studies, and kinetic analyses of the degenerate exchange of methane in the methyl complex [Tp(Me2)NbCH3(c-C3H5)(MeCCMe)] (1) are reported. Stoichiometric methane activation by the mesitylene complex [Tp(Me2)Nb(CH2-3,5-C6H3Me2)(c-C3H5) (MeCCMe)] (2) giving 1 is also realized. Evidence is provided that these reactions proceed via an intramolecular abstraction of a β-H of the cyclopropyl group to form either methane or mesitylene from 1 or 2, respectively, yielding the transient unsaturated η(2)-cyclopropene/metallabicyclobutane intermediate [Tp(Me2)Nb(η(2)-c-C3H4) (MeCCMe)] A. This is followed by its mechanistic reverse 1,3-CH bond addition of methane yielding the product. PMID:26374390

  19. Transient Spectroscopic Characterization of the Genesis of a Ruthenium Complex Catalyst Supported on Zeolite Y

    SciTech Connect

    Ogino, Isao; Gates, Bruce C.

    2010-01-12

    A mononuclear ruthenium complex anchored to dealuminated zeolite HY, Ru(acac)(C{sub 2}H{sub 4}){sup 2+} (acac = acetylacetonate, C{sub 5}H{sub 7}O{sup 2}{sup -}), was characterized in flow reactors by transient infrared (IR) spectroscopy and Ru K edge X-ray absorption spectroscopy. The combined results show how the supported complex was converted into a form that catalyzes ethene conversion to butene. The formation of these species resulted from the removal of acac ligands from the ruthenium (as shown by IR and extended X-ray absorption fine structure (EXAFS) spectra) and the simultaneous decrease in the symmetry of the ruthenium complex, with the ruthenium remaining mononuclear and its oxidation state remaining essentially unchanged (as shown by EXAFS and X-ray absorption near-edge structure spectra). The removal of anionic acac ligands from the ruthenium was evidently compensated by the bonding of other anionic ligands, such as hydride from H2 in the feed stream, to form species suggested to be Ru(H)(C{sub 2}H{sub 4}){sub 2}{sup +}, which is coordinatively unsaturated and inferred to react with ethene, leading to the observed formation of butene in a catalytic process.

  20. Extreme events in multilayer, interdependent complex networks and control

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Zhong; Huang, Zi-Gang; Zhang, Hai-Feng; Eisenberg, Daniel; Seager, Thomas P.; Lai, Ying-Cheng

    2015-11-01

    We investigate the emergence of extreme events in interdependent networks. We introduce an inter-layer traffic resource competing mechanism to account for the limited capacity associated with distinct network layers. A striking finding is that, when the number of network layers and/or the overlap among the layers are increased, extreme events can emerge in a cascading manner on a global scale. Asymptotically, there are two stable absorption states: a state free of extreme events and a state of full of extreme events, and the transition between them is abrupt. Our results indicate that internal interactions in the multiplex system can yield qualitatively distinct phenomena associated with extreme events that do not occur for independent network layers. An implication is that, e.g., public resource competitions among different service providers can lead to a higher resource requirement than naively expected. We derive an analytical theory to understand the emergence of global-scale extreme events based on the concept of effective betweenness. We also articulate a cost-effective control scheme through increasing the capacity of very few hubs to suppress the cascading process of extreme events so as to protect the entire multi-layer infrastructure against global-scale breakdown.

  1. Mediterranean circulation perturbations over the last five centuries: Relevance to past Eastern Mediterranean Transient-type events.

    PubMed

    Incarbona, Alessandro; Martrat, Belen; Mortyn, P Graham; Sprovieri, Mario; Ziveri, Patrizia; Gogou, Alexandra; Jordà, Gabriel; Xoplaki, Elena; Luterbacher, Juerg; Langone, Leonardo; Marino, Gianluca; Rodríguez-Sanz, Laura; Triantaphyllou, Maria; Di Stefano, Enrico; Grimalt, Joan O; Tranchida, Giorgio; Sprovieri, Rodolfo; Mazzola, Salvatore

    2016-01-01

    The Eastern Mediterranean Transient (EMT) occurred in the Aegean Sea from 1988 to 1995 and is the most significant intermediate-to-deep Mediterranean overturning perturbation reported by instrumental records. The EMT was likely caused by accumulation of high salinity waters in the Levantine and enhanced heat loss in the Aegean Sea, coupled with surface water freshening in the Sicily Channel. It is still unknown whether similar transients occurred in the past and, if so, what their forcing processes were. In this study, sediments from the Sicily Channel document surface water freshening (SCFR) at 1910 ± 12, 1812 ± 18, 1725 ± 25 and 1580 ± 30 CE. A regional ocean hindcast links SCFR to enhanced deep-water production and in turn to strengthened Mediterranean thermohaline circulation. Independent evidence collected in the Aegean Sea supports this reconstruction, showing that enhanced bottom water ventilation in the Eastern Mediterranean was associated with each SCFR event. Comparison between the records and multi-decadal atmospheric circulation patterns and climatic external forcings indicates that Mediterranean circulation destabilisation occurs during positive North Atlantic Oscillation (NAO) and negative Atlantic Multidecadal Oscillation (AMO) phases, reduced solar activity and strong tropical volcanic eruptions. They may have recurrently produced favourable deep-water formation conditions, both increasing salinity and reducing temperature on multi-decadal time scales. PMID:27412622

  2. Mediterranean circulation perturbations over the last five centuries: Relevance to past Eastern Mediterranean Transient-type events

    NASA Astrophysics Data System (ADS)

    Incarbona, Alessandro; Martrat, Belen; Mortyn, P. Graham; Sprovieri, Mario; Ziveri, Patrizia; Gogou, Alexandra; Jordà, Gabriel; Xoplaki, Elena; Luterbacher, Juerg; Langone, Leonardo; Marino, Gianluca; Rodríguez-Sanz, Laura; Triantaphyllou, Maria; di Stefano, Enrico; Grimalt, Joan O.; Tranchida, Giorgio; Sprovieri, Rodolfo; Mazzola, Salvatore

    2016-07-01

    The Eastern Mediterranean Transient (EMT) occurred in the Aegean Sea from 1988 to 1995 and is the most significant intermediate-to-deep Mediterranean overturning perturbation reported by instrumental records. The EMT was likely caused by accumulation of high salinity waters in the Levantine and enhanced heat loss in the Aegean Sea, coupled with surface water freshening in the Sicily Channel. It is still unknown whether similar transients occurred in the past and, if so, what their forcing processes were. In this study, sediments from the Sicily Channel document surface water freshening (SCFR) at 1910 ± 12, 1812 ± 18, 1725 ± 25 and 1580 ± 30 CE. A regional ocean hindcast links SCFR to enhanced deep-water production and in turn to strengthened Mediterranean thermohaline circulation. Independent evidence collected in the Aegean Sea supports this reconstruction, showing that enhanced bottom water ventilation in the Eastern Mediterranean was associated with each SCFR event. Comparison between the records and multi-decadal atmospheric circulation patterns and climatic external forcings indicates that Mediterranean circulation destabilisation occurs during positive North Atlantic Oscillation (NAO) and negative Atlantic Multidecadal Oscillation (AMO) phases, reduced solar activity and strong tropical volcanic eruptions. They may have recurrently produced favourable deep-water formation conditions, both increasing salinity and reducing temperature on multi-decadal time scales.

  3. Mediterranean circulation perturbations over the last five centuries: Relevance to past Eastern Mediterranean Transient-type events

    PubMed Central

    Incarbona, Alessandro; Martrat, Belen; Mortyn, P. Graham; Sprovieri, Mario; Ziveri, Patrizia; Gogou, Alexandra; Jordà, Gabriel; Xoplaki, Elena; Luterbacher, Juerg; Langone, Leonardo; Marino, Gianluca; Rodríguez-Sanz, Laura; Triantaphyllou, Maria; Di Stefano, Enrico; Grimalt, Joan O.; Tranchida, Giorgio; Sprovieri, Rodolfo; Mazzola, Salvatore

    2016-01-01

    The Eastern Mediterranean Transient (EMT) occurred in the Aegean Sea from 1988 to 1995 and is the most significant intermediate-to-deep Mediterranean overturning perturbation reported by instrumental records. The EMT was likely caused by accumulation of high salinity waters in the Levantine and enhanced heat loss in the Aegean Sea, coupled with surface water freshening in the Sicily Channel. It is still unknown whether similar transients occurred in the past and, if so, what their forcing processes were. In this study, sediments from the Sicily Channel document surface water freshening (SCFR) at 1910 ± 12, 1812 ± 18, 1725 ± 25 and 1580 ± 30 CE. A regional ocean hindcast links SCFR to enhanced deep-water production and in turn to strengthened Mediterranean thermohaline circulation. Independent evidence collected in the Aegean Sea supports this reconstruction, showing that enhanced bottom water ventilation in the Eastern Mediterranean was associated with each SCFR event. Comparison between the records and multi-decadal atmospheric circulation patterns and climatic external forcings indicates that Mediterranean circulation destabilisation occurs during positive North Atlantic Oscillation (NAO) and negative Atlantic Multidecadal Oscillation (AMO) phases, reduced solar activity and strong tropical volcanic eruptions. They may have recurrently produced favourable deep-water formation conditions, both increasing salinity and reducing temperature on multi-decadal time scales. PMID:27412622

  4. System level latchup mitigation for single event and transient radiation effects on electronics

    SciTech Connect

    Kimbrough, J.R.; Colella, N.J.

    1994-12-31

    A `blink` technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection means, power dump logic means, and energy limiting measures with autonomous recovery. The event detection means includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The current sensing means is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation. The power dump means includes power dump logic means having a first input terminal connected to the output terminal of the ionizing radiation pulse detection means and having a second input terminal connected to the output terminal of the current sensing means. The power dump logic means provides an output signal to the input terminal of the means for opening the power bus and the means for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting mean with autonomous recovery includes means for opening the power bus and means for shorting the power bus to a ground potential. The means for opening the power bus and means for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements.

  5. System level latchup mitigation for single event and transient radiation effects on electronics

    DOEpatents

    Kimbrough, J.R.; Colella, N.J.

    1997-09-30

    A ``blink`` technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection circuitry, power dump logic circuitry, and energy limiting measures with autonomous recovery. The event detection circuitry includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation. The current sensing circuitry is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The power dump circuitry includes power dump logic circuitry having a first input terminal connected to the output terminal of the ionizing radiation pulse detection circuitry and having a second input terminal connected to the output terminal of the current sensing circuitry. The power dump logic circuitry provides an output signal to the input terminal of the circuitry for opening the power bus and the circuitry for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting circuitry with autonomous recovery includes circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential. The circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements. 18 figs.

  6. System level latchup mitigation for single event and transient radiation effects on electronics

    DOEpatents

    Kimbrough, Joseph Robert; Colella, Nicholas John

    1997-01-01

    A "blink" technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection circuitry, power dump logic circuitry, and energy limiting measures with autonomous recovery. The event detection circuitry includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation. The current sensing circuitry is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The power dump circuitry includes power dump logic circuitry having a first input terminal connected to the output terminal of the ionizing radiation pulse detection circuitry and having a second input terminal connected to the output terminal of the current sensing circuitry. The power dump logic circuitry provides an output signal to the input terminal of the circuitry for opening the power bus and the circuitry for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting circuitry with autonomous recovery includes circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential. The circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements.

  7. High time resolution observation of the transient event of 5 March 1979

    NASA Technical Reports Server (NTRS)

    Weisskopf, M. C.; Darbro, W.; Ghosh, P.; Sutherland, P. G.; Grindlay, J.

    1980-01-01

    The detection of an intense gamma ray burst with the monitor proportional counter on the HEAO 2 spacecraft is discussed with particular emphasis on the measurement of the time of onset of the event. Based on the mean observed counting rate in the burst and assuming a sharp rise, the uncertainty in the burst onset is found to be + or - 220 microseconds. The time of occurrence was 57124.826908 + or - 0.000220 s UT on March 5, 1979, and the location of the HEAO 2 satellite at this time was latitude 22.15 deg, longitude -27.60 deg at an altitude of 525.0 km.

  8. The ultraviolet-bright, slowly declining transient PS1-11af as a partial tidal disruption event

    SciTech Connect

    Chornock, R.; Berger, E.; Zauderer, B. A.; Kamble, A.; Soderberg, A. M.; Czekala, I.; Dittmann, J.; Drout, M.; Foley, R. J.; Fong, W.; Kirshner, R. P.; Lunnan, R.; Marion, G. H.; Narayan, G.; Gezari, S.; Rest, A.; Riess, A. G.; Chomiuk, L.; Huber, M. E.; Lawrence, A.; and others

    2014-01-01

    We present the Pan-STARRS1 discovery of the long-lived and blue transient PS1-11af, which was also detected by Galaxy Evolution Explorer with coordinated observations in the near-ultraviolet (NUV) band. PS1-11af is associated with the nucleus of an early type galaxy at redshift z = 0.4046 that exhibits no evidence for star formation or active galactic nucleus activity. Four epochs of spectroscopy reveal a pair of transient broad absorption features in the UV on otherwise featureless spectra. Despite the superficial similarity of these features to P-Cygni absorptions of supernovae (SNe), we conclude that PS1-11af is not consistent with the properties of known types of SNe. Blackbody fits to the spectral energy distribution are inconsistent with the cooling, expanding ejecta of a SN, and the velocities of the absorption features are too high to represent material in homologous expansion near a SN photosphere. However, the constant blue colors and slow evolution of the luminosity are similar to previous optically selected tidal disruption events (TDEs). The shape of the optical light curve is consistent with models for TDEs, but the minimum accreted mass necessary to power the observed luminosity is only ∼0.002 M {sub ☉}, which points to a partial disruption model. A full disruption model predicts higher bolometric luminosities, which would require most of the radiation to be emitted in a separate component at high energies where we lack observations. In addition, the observed temperature is lower than that predicted by pure accretion disk models for TDEs and requires reprocessing to a constant, lower temperature. Three deep non-detections in the radio with the Very Large Array over the first two years after the event set strict limits on the production of any relativistic outflow comparable to Swift J1644+57, even if off-axis.

  9. NREM sleep transient events in fronto-temporal dementia: beyond sleep stage architecture.

    PubMed

    Maestri, Michelangelo; Carnicelli, Luca; Economou, Nicholas-Tiberio; Bonakis, Anastasios; Paparrigopoulos, Thomas; Papageorgiou, Sokratis T; Giorgi, Filippo Sean; Di Coscio, Elisa; Tognoni, Gloria; Ferri, Raffaele; Bonuccelli, Ubaldo; Bonanni, Enrica

    2015-01-01

    Frontotemporal dementia (FTD) is increasingly becoming recognized as a major cause of early onset (<65 years) neurodegenerative dementia. Although sleep disorders significantly impair patients' and caregivers' quality of life in neurodegenerative diseases, polysomnographic data in FTD patients are scarce in literature. Aim of our study was to investigate sleep microstructure in FTD, by means of Cyclic Alternating Pattern (CAP), in a group of ten behavioral variant FTD patients (6 M, 4 F; mean age 61.2±7.3 years; disease duration: 1.4±0.7 years) and to compare them with cognitively intact healthy elderly. Sleep in FTD patients was altered at different levels, involving not only the conventional sleep stage architecture parameters (total sleep time, single stage percentage, NREM/REM cycle organization), but also microstructure. FTD subjects showed CAP disruption with decreased slow wave activity related phases (A1 index, n/h:14.5±6.8 vs 38.8±6.6; p<.001) and increased arousal-related fast CAP components (A2 index 22.9±8.2 vs 11.6±3.7; p=.006; A3 index 41.9±20.7 vs 13.0±6.5; p=.002). Several correlations between sleep variables and neuropsychological tests were found. Sleep impairment in FTD may be specifically related to the specific frontal lobe involvement in the neurodegenerative process. The pattern of alterations seems somewhat peculiar, probably due to the anatomical distribution of the neurodegenerative process with a major impact on frontal lobe generated sleep transients, and a substantial sparing of phenomena related to the posterior cortex. PMID:26742675

  10. A transient heating event in the history of a highlands troctolite from Apollo 12 soil 12033

    NASA Astrophysics Data System (ADS)

    Marvin, U. B.; Walker, D.

    1985-02-01

    A 2-mm particle, consisting of a troctolite clast attached to a small amount of glassy soil breccia, was found in a thin section of grains from Apollo 12 sample 12033,66. A description is given of the evolutionary history of the troctolite, taking into account the unique texture. It appears that the particle was broken from its parent rock and projected to Oceanus Procellarum from a source area in the highlands. Before, during, or after the flight, the troctolite was welded to a soil breccia by a minor amount of melting along the contact. It is argued that two separate heating events may be involved. The hypothesis is considered that the partial remelting and quenching of the troctolite took place very rapidly. Attention is given to melting experiments which test and confirm this hypothesis.

  11. Modeling Non-Steady Isotopic Effects Caused by Biological Kinetic Transient Complexation During Denitrification in Soils

    NASA Astrophysics Data System (ADS)

    Maggi, F.; Riley, W. J.

    2008-12-01

    The composition and location of 15N atoms on N2O molecules has been used to characterize soil biological N cycling and N2O surface emissions. Besides the complexity of the processes related to N2O transformations and movements (e.g., chain-like denitrification reaction, soil moisture and temperature dynamics, aqueous and gaseous advection and diffusion) which make interpretation of the isotopic N2O composition very difficult, a theoretical aspect has been overlooked. The theoretical formulation of biological kinetic reactions in isotopic applications makes common use of first-order and quasi steady-state assumptions, according to which the rates of change of the concentration of intermediate complexes can be neglected. When isotopically-labeled reactants are used, these assumptions are not necessarily accurate since isotopic effects during complexation occur at orders of magnitude that compare with the truncation used under first-order and quasi steady-state conditions. Both assumptions, in fact, always lead to a constant fractionation factor and may therefore yield incorrect estimates of the isotopic effect and a misleading interpretation of the reaction signature. We have analyzed the isotopic signature of denitrification in biogeochemical soil systems reported by Menyailo and Hungate (2006), where high 15N2O enrichment during N2O production and inverse isotope fractionation during N2O consumption could not be explained with first-order kinetics and the Rayleigh equation, or with quasi steady-state Monod kinetics. When the quasi steady-state assumption was relaxed, transient Monod kinetics accounting for isotopic effect occurring at the complexes accurately reproduced the observations and aided in interpretation of experimental isotopic signatures. These results may imply a substantial revision in using the Rayleigh equation for interpretation and in modeling biological kinetic isotope fractionation with first-order kinetics or quasi steady state Monod kinetics.

  12. Self-Complexity, Daily Events, and Perceived Quality of Life.

    ERIC Educational Resources Information Center

    Kardash, CarolAnne M.; Okun, Morris A.

    Recent research has demonstrated that self-cognitions can play an important role in physical and emotional well-being. One important aspect of self-cognition concerns the complexity of self-representations. This study tested the hypothesis that self-complexity, as assessed by Linville's self-trait sorting task, would moderate the effects of…

  13. Transient receptor potential channel 1 (TRPC1) reduces calcium permeability in heteromeric channel complexes.

    PubMed

    Storch, Ursula; Forst, Anna-Lena; Philipp, Maximilian; Gudermann, Thomas; Mederos y Schnitzler, Michael

    2012-01-27

    Specific biological roles of the classical transient receptor potential channel 1 (TRPC1) are still largely elusive. To investigate the function of TRPC1 proteins in cell physiology, we studied heterologously expressed TRPC1 channels and found that recombinant TRPC1 subunits do not form functional homomeric channels. Instead, by electrophysiological analysis TRPC1 was shown to form functional heteromeric, receptor-operated channel complexes with TRPC3, -4, -5, -6, and -7 indicating that TRPC1 proteins can co-assemble with all members of the TRPC subfamily. In all TRPC1-containing heteromers, TRPC1 subunits significantly decreased calcium permeation. The exchange of select amino acids in the putative pore-forming region of TRPC1 further reduced calcium permeability, suggesting that TRPC1 subunits contribute to the channel pore. In immortalized immature gonadotropin-releasing hormone neurons endogenously expressing TRPC1, -2, -5, and -6, down-regulation of TRPC1 resulted in increased calcium permeability and elevated basal cytosolic calcium concentrations. We did not observe any involvement of TRPC1 in store-operated cation influx. Notably, TRPC1 suppressed the migration of gonadotropin-releasing hormone neurons without affecting cell proliferation. Conversely, in TRPC1 knockdown neurons, specific migratory properties like distance covered, locomotion speed, and directionality were increased. These findings suggest a novel regulatory mechanism relying on the expression of TRPC1 and the subsequent formation of heteromeric TRPC channel complexes with reduced calcium permeability, thereby fine-tuning neuronal migration. PMID:22157757

  14. Transient Receptor Potential Channel 1 (TRPC1) Reduces Calcium Permeability in Heteromeric Channel Complexes

    PubMed Central

    Storch, Ursula; Forst, Anna-Lena; Philipp, Maximilian; Gudermann, Thomas; Mederos y Schnitzler, Michael

    2012-01-01

    Specific biological roles of the classical transient receptor potential channel 1 (TRPC1) are still largely elusive. To investigate the function of TRPC1 proteins in cell physiology, we studied heterologously expressed TRPC1 channels and found that recombinant TRPC1 subunits do not form functional homomeric channels. Instead, by electrophysiological analysis TRPC1 was shown to form functional heteromeric, receptor-operated channel complexes with TRPC3, -4, -5, -6, and -7 indicating that TRPC1 proteins can co-assemble with all members of the TRPC subfamily. In all TRPC1-containing heteromers, TRPC1 subunits significantly decreased calcium permeation. The exchange of select amino acids in the putative pore-forming region of TRPC1 further reduced calcium permeability, suggesting that TRPC1 subunits contribute to the channel pore. In immortalized immature gonadotropin-releasing hormone neurons endogenously expressing TRPC1, -2, -5, and -6, down-regulation of TRPC1 resulted in increased calcium permeability and elevated basal cytosolic calcium concentrations. We did not observe any involvement of TRPC1 in store-operated cation influx. Notably, TRPC1 suppressed the migration of gonadotropin-releasing hormone neurons without affecting cell proliferation. Conversely, in TRPC1 knockdown neurons, specific migratory properties like distance covered, locomotion speed, and directionality were increased. These findings suggest a novel regulatory mechanism relying on the expression of TRPC1 and the subsequent formation of heteromeric TRPC channel complexes with reduced calcium permeability, thereby fine-tuning neuronal migration. PMID:22157757

  15. Rapid processing of chemosensor transients in a neuromorphic implementation of the insect macroglomerular complex

    PubMed Central

    Pearce, Timothy C.; Karout, Salah; Rácz, Zoltán; Capurro, Alberto; Gardner, Julian W.; Cole, Marina

    2012-01-01

    We present a biologically-constrained neuromorphic spiking model of the insect antennal lobe macroglomerular complex that encodes concentration ratios of chemical components existing within a blend, implemented using a set of programmable logic neuronal modeling cores. Depending upon the level of inhibition and symmetry in its inhibitory connections, the model exhibits two dynamical regimes: fixed point attractor (winner-takes-all type), and limit cycle attractor (winnerless competition type) dynamics. We show that, when driven by chemosensor input in real-time, the dynamical trajectories of the model's projection neuron population activity accurately encode the concentration ratios of binary odor mixtures in both dynamical regimes. By deploying spike timing-dependent plasticity in a subset of the synapses in the model, we demonstrate that a Hebbian-like associative learning rule is able to organize weights into a stable configuration after exposure to a randomized training set comprising a variety of input ratios. Examining the resulting local interneuron weights in the model shows that each inhibitory neuron competes to represent possible ratios across the population, forming a ratiometric representation via mutual inhibition. After training the resulting dynamical trajectories of the projection neuron population activity show amplification and better separation in their response to inputs of different ratios. Finally, we demonstrate that by using limit cycle attractor dynamics, it is possible to recover and classify blend ratio information from the early transient phases of chemosensor responses in real-time more rapidly and accurately compared to a nearest-neighbor classifier applied to the normalized chemosensor data. Our results demonstrate the potential of biologically-constrained neuromorphic spiking models in achieving rapid and efficient classification of early phase chemosensor array transients with execution times well beyond biological timescales. PMID

  16. Transient Events and Landscape Response in Boulder Creek, Colorado Front Range (Invited)

    NASA Astrophysics Data System (ADS)

    Anderson, S. P.; Duehnforth, M.; Anderson, R. S.; Berlin, M. M.; Dethier, D. P.; Tucker, G. E.; Wobus, C. W.; Blum, A.; Leopold, M.; Williams, M. W.; Befus, K. M.; Sheehan, A. F.

    2009-12-01

    Climate affects the tempo and style of erosion and weathering processes, which together shape the Critical Zone. Here we examine how interplay between these processes over the Quaternary and longer timescales are reflected in the landscape of the Colorado Front Range. Boulder Creek watershed contains widely differing landscapes that arise from climatically controlled late Cenozoic events inscribed on what was probably a slowly evolving post-Laramide landscape. Although large tracts of the rolling, post-Laramide upland still exist, Pleistocene glaciation carved the headwaters of the range, and late Pliocene-Pleistocene fluvial downcutting sliced into the mountain front and adjoining plains (and continues to the present). Landscapes in the headwaters and mountain front continue to respond to these events. In the headwaters, Quaternary glacial erosion removed regolith, and its interglacial inventory of cosmogenic radionuclides, leaving behind a stepped, unweathered bedrock valley floor. Post-glacial modifications have been relatively minor in the ~15-13 ka since glacial retreat. Talus accumulations, with or without interstitial ice, dominate the mobile debris on the valley walls and floor. Soils are developed on deposits, such as under talus or on pockets of till, and contain important dust additions. In contrast, the upstream migration of a fluvial knickpoint into the crystalline rocks of the mountain front formed Boulder Canyon (and other Front Range canyons) and incited ongoing landscape adjustment over the last few million years. At the knickpoint, the canyon is narrow, defined by steep bedrock walls with up to 300 m of local relief, cut into a high, low relief landscape. Downstream of the knickpoint, two processes broaden and open up the canyon. The inclinations of channel-bounding hillslopes decline downstream of the knickpoint. In addition, canyon walls are dissected by the generation and extension of tributary channels that cut into the rolling upland; the

  17. ADELE sensitivity to high-energy radiation from transient luminous events during the Hurricane and Severe Storm Sentinels campaigns

    NASA Astrophysics Data System (ADS)

    Bowers, G.; Smith, D. M.; Dwyer, J. R.; Cummer, S. A.; Martinez-Mckinney, F.; Kelley, N. A.; Harris, C. B.; Buzbee, P.

    2012-12-01

    In the summers of 2013 and 2014, UCSC will fly the Airborne Detector for Energetic Lightning Emissions (ADELE) instrument on board one of the Global Hawk aircraft of the NASA Hurricane and Severe Storm Sentinels (HS3) campaign over storms in the Atlantic. In addition to Terrestrial Gamma-ray Flashes (TGFs), which have been observed at gamma-ray energies by satellites such as RHESSI and FERMI, ADELE will also search for high-energy radiation from Transient Luminous Events (TLEs, i.e. elves, gigantic jets, blue jets, sprites, and sprite halos). High-energy radiation is plausible as a byproduct of stepped leaders in jets, streamers in sprites, and acceleration of electrons in the electromagnetic pulse (EMP) that produces elves. Because ADELE will fly at low altitudes, the intensity of radiation from these events could be orders of magnitude higher at ADELE than at satellites in low earth orbit. We will consider the high energy spectra that might be produced by TLEs and estimate to what extent these phenomena can be observed by ADELE on HS3.

  18. Scale invariance of temporal order discrimination using complex, naturalistic events

    PubMed Central

    Kwok, Sze Chai; Macaluso, Emiliano

    2015-01-01

    Recent demonstrations of scale invariance in cognitive domains prompted us to investigate whether a scale-free pattern might exist in retrieving the temporal order of events from episodic memory. We present four experiments using an encoding-retrieval paradigm with naturalistic stimuli (movies or video clips). Our studies show that temporal order judgement retrieval times were negatively correlated with the temporal separation between two events in the movie. This relation held, irrespective of whether temporal distances were on the order of tens of minutes (Exp 1−2) or just a few seconds (Exp 3−4). Using the SIMPLE model, we factored in the retention delays between encoding and retrieval (delays of 24 h, 15 min, 1.5–2.5 s, and 0.5 s for Exp 1–4, respectively) and computed a temporal similarity score for each trial. We found a positive relation between similarity and retrieval times; that is, the more temporally similar two events, the slower the retrieval of their temporal order. Using Bayesian analysis, we confirmed the equivalence of the RT/similarity relation across all experiments, which included a vast range of temporal distances and retention delays. These results provide evidence for scale invariance during the retrieval of temporal order of episodic memories. PMID:25909581

  19. Scale invariance of temporal order discrimination using complex, naturalistic events.

    PubMed

    Kwok, Sze Chai; Macaluso, Emiliano

    2015-07-01

    Recent demonstrations of scale invariance in cognitive domains prompted us to investigate whether a scale-free pattern might exist in retrieving the temporal order of events from episodic memory. We present four experiments using an encoding-retrieval paradigm with naturalistic stimuli (movies or video clips). Our studies show that temporal order judgement retrieval times were negatively correlated with the temporal separation between two events in the movie. This relation held, irrespective of whether temporal distances were on the order of tens of minutes (Exp 1-2) or just a few seconds (Exp 3-4). Using the SIMPLE model, we factored in the retention delays between encoding and retrieval (delays of 24 h, 15 min, 1.5-2.5 s, and 0.5 s for Exp 1-4, respectively) and computed a temporal similarity score for each trial. We found a positive relation between similarity and retrieval times; that is, the more temporally similar two events, the slower the retrieval of their temporal order. Using Bayesian analysis, we confirmed the equivalence of the RT/similarity relation across all experiments, which included a vast range of temporal distances and retention delays. These results provide evidence for scale invariance during the retrieval of temporal order of episodic memories. PMID:25909581

  20. Affective and Cardiovascular Responding to Unpleasant Events from Adolescence to Old Age: Complexity of Events Matters

    ERIC Educational Resources Information Center

    Wrzus, Cornelia; Muller, Viktor; Wagner, Gert G.; Lindenberger, Ulman; Riediger, Michaela

    2013-01-01

    Two studies investigated the "overpowering hypothesis" as a possible explanation for the currently inconclusive empirical picture on age differences in affective responding to unpleasant events. The overpowering hypothesis predicts that age differences in affective responding are particularly evident in highly resource-demanding situations that…

  1. Short relaxation times but long transient times in both simple and complex reaction networks.

    PubMed

    Henry, Adrien; Martin, Olivier C

    2016-07-01

    When relaxation towards an equilibrium or steady state is exponential at large times, one usually considers that the associated relaxation time τ, i.e. the inverse of the decay rate, is the longest characteristic time in the system. However, that need not be true, other times such as the lifetime of an infinitesimal perturbation can be much longer. In the present work, we demonstrate that this paradoxical property can arise even in quite simple systems such as a linear chain of reactions obeying mass action (MA) kinetics. By mathematical analysis of simple reaction networks, we pin-point the reason why the standard relaxation time does not provide relevant information on the potentially long transient times of typical infinitesimal perturbations. Overall, we consider four characteristic times and study their behaviour in both simple linear chains and in more complex reaction networks taken from the publicly available database 'Biomodels'. In all these systems, whether involving MA rates, Michaelis-Menten reversible kinetics, or phenomenological laws for reaction rates, we find that the characteristic times corresponding to lifetimes of tracers and of concentration perturbations can be significantly longer than τ. PMID:27411726

  2. Transient and persistent pain induced connectivity alterations in pediatric complex regional pain syndrome.

    PubMed

    Linnman, Clas; Becerra, Lino; Lebel, Alyssa; Berde, Charles; Grant, P Ellen; Borsook, David

    2013-01-01

    Evaluation of pain-induced changes in functional connectivity was performed in pediatric complex regional pain syndrome (CRPS) patients. High field functional magnetic resonance imaging was done in the symptomatic painful state and at follow up in the asymptomatic pain free/recovered state. Two types of connectivity alterations were defined: (1) Transient increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb vs. unaffected limb in the CRPS state, but with normalized connectivity patterns in the recovered state; and (2) Persistent increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb as compared to the unaffected limb that persisted also in the recovered state (recovered affected limb versus recovered unaffected limb). The data support the notion that even after symptomatic recovery, alterations in brain systems persist, particularly in amygdala and basal ganglia systems. Connectivity analysis may provide a measure of temporal normalization of different circuits/regions when evaluating therapeutic interventions for this condition. The results add emphasis to the importance of early recognition and management in improving outcome of pediatric CRPS. PMID:23526938

  3. Transient and Persistent Pain Induced Connectivity Alterations in Pediatric Complex Regional Pain Syndrome

    PubMed Central

    Linnman, Clas; Becerra, Lino; Lebel, Alyssa; Berde, Charles; Grant, P. Ellen; Borsook, David

    2013-01-01

    Evaluation of pain-induced changes in functional connectivity was performed in pediatric complex regional pain syndrome (CRPS) patients. High field functional magnetic resonance imaging was done in the symptomatic painful state and at follow up in the asymptomatic pain free/recovered state. Two types of connectivity alterations were defined: (1) Transient increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb vs. unaffected limb in the CRPS state, but with normalized connectivity patterns in the recovered state; and (2) Persistent increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb as compared to the unaffected limb that persisted also in the recovered state (recovered affected limb versus recovered unaffected limb). The data support the notion that even after symptomatic recovery, alterations in brain systems persist, particularly in amygdala and basal ganglia systems. Connectivity analysis may provide a measure of temporal normalization of different circuits/regions when evaluating therapeutic interventions for this condition. The results add emphasis to the importance of early recognition and management in improving outcome of pediatric CRPS. PMID:23526938

  4. Short relaxation times but long transient times in both simple and complex reaction networks

    PubMed Central

    Henry, Adrien; Martin, Olivier C.

    2016-01-01

    When relaxation towards an equilibrium or steady state is exponential at large times, one usually considers that the associated relaxation time τ, i.e. the inverse of the decay rate, is the longest characteristic time in the system. However, that need not be true, other times such as the lifetime of an infinitesimal perturbation can be much longer. In the present work, we demonstrate that this paradoxical property can arise even in quite simple systems such as a linear chain of reactions obeying mass action (MA) kinetics. By mathematical analysis of simple reaction networks, we pin-point the reason why the standard relaxation time does not provide relevant information on the potentially long transient times of typical infinitesimal perturbations. Overall, we consider four characteristic times and study their behaviour in both simple linear chains and in more complex reaction networks taken from the publicly available database ‘Biomodels’. In all these systems, whether involving MA rates, Michaelis–Menten reversible kinetics, or phenomenological laws for reaction rates, we find that the characteristic times corresponding to lifetimes of tracers and of concentration perturbations can be significantly longer than τ. PMID:27411726

  5. Management of a Complex Open Channel Network During Flood Events

    NASA Astrophysics Data System (ADS)

    Franchini, M.; Valiani, A.; Schippa, L.; Mascellani, G.

    2003-04-01

    Most part of the area around Ferrara (Italy) is below the mean sea level and an extensive drainage system combined with several pump stations allows the use of this area for both urban development and industrial and agricultural activities. The three main channels of this hydraulic system constitute the Ferrara Inland Waterway (total length approximately 70 km), which connects the Po river near Ferrara to the sea. Because of the level difference between the upstream and dowstream ends of the waterway, three locks are located along it, each of them combined with a set of gates to control the water levels. During rainfall events, most of the water of the basin flows into the waterway and heavy precipitations sometimes cause flooding in several areas. This is due to the insufficiency of the channel network dimensions and an inadequate manual operation of the gates. This study presents a hydrological-hydraulic model for the entire Ferrara basin and a system of rules in order to operate the gates. In particular, their opening is designed to be regulated in real time by monitoring the water level in several sections along the channels. Besides flood peak attenuation, this operation strategy contributes also to the maintenance of a constant water level for irrigation and fluvial navigation during the dry periods. With reference to the flood event of May 1996, it is shown that this floodgate operation policy, unlike that which was actually adopted during that event, would lead to a significant flood peak attenuation, avoiding flooding in the area upstream of Ferrara.

  6. Transient-state kinetic analysis of complex formation between photoprotein clytin and GFP from jellyfish Clytia gregaria.

    PubMed

    Eremeeva, Elena V; van Berkel, Willem J H; Vysotski, Eugene S

    2016-02-01

    Luminous organisms use different protein-mediated strategies to modulate light emission color. Here, we report the transient-state kinetic studies of the interaction between photoprotein clytin from Clytia gregaria and its antenna protein, cgreGFP. We propose that cgreGFP forms a transient complex with Ca(2+)-bound clytin before the excited singlet state of the coelenteramide product is formed. From the spectral distribution and donor-acceptor separation distance, we infer that clytin reaction intermediates may interact only with the middle side part of cgreGFP. PMID:26867648

  7. Simulation of the infrared signature of transient luminous events in the middle atmosphere for a limb line of sight

    NASA Astrophysics Data System (ADS)

    Romand, Frédéric; Croizé, Laurence; Payan, Sébastien; Huret, Nathalie

    2016-04-01

    Transient Luminous Events (TLE) are electrical and optical events which occurs above thunderstorms. Visual signatures are reported since the beginning of the 20th century but the first picture is accidentally recorded from a television camera in 1989. Their occurrence is closely linked with the lightning activity below thunderstorms. TLEs are observed from the base of the stratosphere to the thermosphere (15 - 110 km). They are a very brief phenomenon which lasts from 1 to 300 milliseconds. At a worldwide scale, four TLEs occur each minute. The energy deposition, about some tenth of megajoules, is able to ionize, dissociate and excite the molecules of the atmosphere. Atmospheric discharges in the troposphere are important sources of NO and NO2. TLEs might have the same effects at higher altitudes, in the stratosphere. NOx then can affect the concentration of O3 and OH. Consequently, TLEs could be locally important contributors to the chemical budget of the middle atmosphere. The perturbation of the atmospheric chemistry induced by TLEs has the consequence to locally modify the radiations in the infrared during the minutes following the event. The interest of studying the infrared signature of a TLE is twofold. For the atmospheric sciences it allows to link the perturbed composition to the resulting infrared spectrum. Then, some Defense systems like detection and guiding devices are equipped with airborne infrared sensors so that the TLE infrared signature might disturb them. We want to obtain a quantitative and kinetic evaluation of the infrared signature of the atmosphere locally perturbed by a TLE. In order to do so we must model three phenomena. 1) The plasma/chemistry coupling, which describes how the different energetic levels of atmospheric molecules are populated by the energetic deposition of the TLE. This step lasts the time of the lightning itself. 2) The chemical kinetics which describes how these populations will evolve in the following minutes. 3) The

  8. Robot traders can prevent extreme events in complex stock markets

    NASA Astrophysics Data System (ADS)

    Suhadolnik, Nicolas; Galimberti, Jaqueson; Da Silva, Sergio

    2010-11-01

    If stock markets are complex, monetary policy and even financial regulation may be useless to prevent bubbles and crashes. Here, we suggest the use of robot traders as an anti-bubble decoy. To make our case, we put forward a new stochastic cellular automata model that generates an emergent stock price dynamics as a result of the interaction between traders. After introducing socially integrated robot traders, the stock price dynamics can be controlled, so as to make the market more Gaussian.

  9. Hydraulic Transients in the Long Diversion-Type Hydropower Station with a Complex Differential Surge Tank

    PubMed Central

    Yu, Xiaodong; Zhang, Jian

    2014-01-01

    Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results show that successive load rejection is critical for calculating the maximum pressure in spiral case and the maximum rotating speed of runner when the bifurcated pipe is converging under the surge tank in a diversion-type hydropower station; the pressure difference between two sides of breast wall is large during transient conditions, and it would be more serious when simultaneous load rejections happen after load acceptance; the reasonable arrangement of PROs on breast wall can effectively decrease the pressure difference. PMID:25133213

  10. Moonquakes and Transient Events

    ERIC Educational Resources Information Center

    Middlehurst, Barbara M.

    1973-01-01

    Reviews short term lunar surface changes gathered during the last decade and their relations to the seismic data from the four seismographs placed on the Moon. Indicates that such a continued consideration may give rise to a new insight into the structure of the Moon. (CC)

  11. Enhancing Complex System Performance Using Discrete-Event Simulation

    SciTech Connect

    Allgood, Glenn O; Olama, Mohammed M; Lake, Joe E

    2010-01-01

    In this paper, we utilize discrete-event simulation (DES) merged with human factors analysis to provide the venue within which the separation and deconfliction of the system/human operating principles can occur. A concrete example is presented to illustrate the performance enhancement gains for an aviation cargo flow and security inspection system achieved through the development and use of a process DES. The overall performance of the system is computed, analyzed, and optimized for the different system dynamics. Various performance measures are considered such as system capacity, residual capacity, and total number of pallets waiting for inspection in the queue. These metrics are performance indicators of the system's ability to service current needs and respond to additional requests. We studied and analyzed different scenarios by changing various model parameters such as the number of pieces per pallet ratio, number of inspectors and cargo handling personnel, number of forklifts, number and types of detection systems, inspection modality distribution, alarm rate, and cargo closeout time. The increased physical understanding resulting from execution of the queuing model utilizing these vetted performance measures identified effective ways to meet inspection requirements while maintaining or reducing overall operational cost and eliminating any shipping delays associated with any proposed changes in inspection requirements. With this understanding effective operational strategies can be developed to optimally use personnel while still maintaining plant efficiency, reducing process interruptions, and holding or reducing costs.

  12. Electrostatic interactions in the binding pathway of a transient protein complex studied by NMR and isothermal titration calorimetry.

    PubMed

    Meneses, Erick; Mittermaier, Anthony

    2014-10-01

    Much of our knowledge of protein binding pathways is derived from extremely stable complexes that interact very tightly, with lifetimes of hours to days. Much less is known about weaker interactions and transient complexes because these are challenging to characterize experimentally. Nevertheless, these types of interactions are ubiquitous in living systems. The combination of NMR relaxation dispersion Carr-Purcell-Meiboom-Gill (CPMG) experiments and isothermal titration calorimetry allows the quantification of rapid binding kinetics for complexes with submillisecond lifetimes that are difficult to study using conventional techniques. We have used this approach to investigate the binding pathway of the Src homology 3 (SH3) domain from the Fyn tyrosine kinase, which forms complexes with peptide targets whose lifetimes are on the order of about a millisecond. Long range electrostatic interactions have been shown to play a critical role in the binding pathways of tightly binding complexes. The role of electrostatics in the binding pathways of transient complexes is less well understood. Similarly to previously studied tight complexes, we find that SH3 domain association rates are enhanced by long range electrostatics, whereas short range interactions are formed late in the docking process. However, the extent of electrostatic association rate enhancement is several orders of magnitudes less, whereas the electrostatic-free basal association rate is significantly greater. Thus, the SH3 domain is far less reliant on electrostatic enhancement to achieve rapid association kinetics than are previously studied systems. This suggests that there may be overall differences in the role played by electrostatics in the binding pathways of extremely stable versus transient complexes. PMID:25122758

  13. Electrostatic Interactions in the Binding Pathway of a Transient Protein Complex Studied by NMR and Isothermal Titration Calorimetry*

    PubMed Central

    Meneses, Erick; Mittermaier, Anthony

    2014-01-01

    Much of our knowledge of protein binding pathways is derived from extremely stable complexes that interact very tightly, with lifetimes of hours to days. Much less is known about weaker interactions and transient complexes because these are challenging to characterize experimentally. Nevertheless, these types of interactions are ubiquitous in living systems. The combination of NMR relaxation dispersion Carr–Purcell–Meiboom–Gill (CPMG) experiments and isothermal titration calorimetry allows the quantification of rapid binding kinetics for complexes with submillisecond lifetimes that are difficult to study using conventional techniques. We have used this approach to investigate the binding pathway of the Src homology 3 (SH3) domain from the Fyn tyrosine kinase, which forms complexes with peptide targets whose lifetimes are on the order of about a millisecond. Long range electrostatic interactions have been shown to play a critical role in the binding pathways of tightly binding complexes. The role of electrostatics in the binding pathways of transient complexes is less well understood. Similarly to previously studied tight complexes, we find that SH3 domain association rates are enhanced by long range electrostatics, whereas short range interactions are formed late in the docking process. However, the extent of electrostatic association rate enhancement is several orders of magnitudes less, whereas the electrostatic-free basal association rate is significantly greater. Thus, the SH3 domain is far less reliant on electrostatic enhancement to achieve rapid association kinetics than are previously studied systems. This suggests that there may be overall differences in the role played by electrostatics in the binding pathways of extremely stable versus transient complexes. PMID:25122758

  14. DISCOVERY OF AN ULTRASOFT X-RAY TRANSIENT SOURCE IN THE 2XMM CATALOG: A TIDAL DISRUPTION EVENT CANDIDATE

    SciTech Connect

    Lin Dacheng; Webb, Natalie A.; Barret, Didier; Carrasco, Eleazar R.; Farrell, Sean A.

    2011-09-01

    We have discovered an ultrasoft X-ray transient source, 2XMMi J184725.1-631724, which was detected serendipitously in two XMM-Newton observations in the direction of the center of the galaxy IC 4765-f01-1504 at a redshift of 0.0353. These two observations were separated by 211 days, with the 0.2-10 keV absorbed flux increasing by a factor of about nine. Their spectra are best described by a model dominated by a thermal disk or a single-temperature blackbody component (contributing {approx}>80% of the flux) plus a weak power-law component. The thermal emission has a temperature of a few tens of eV, and the weak power-law component has a photon index of {approx}3.5. Similar to the black hole X-ray binaries in the thermal state, our source exhibits an accretion disk whose luminosity appears to follow the L{proportional_to}T {sup 4} relation. This would indicate that the black hole mass is about 10{sup 5}-10{sup 6} M{sub sun} using the best-fitting inner disk radius. Both XMM-Newton observations show variability of about 21% on timescales of hours, which can be explained as due to fast variations in the mass accretion rate. The source was not detected by ROSAT in an observation in 1992, indicating a variability factor of {approx}>64 over longer timescales. The source was not detected again in X-rays in a Swift observation in 2011 February, implying a flux decrease by a factor of {approx}>12 since the last XMM-Newton observation. The transient nature, in addition to the extreme softness of the X-ray spectra and the inactivity of the galaxy implied by the lack of strong optical emission lines, makes it a candidate tidal disruption event. If this is the case, the first XMM-Newton observation would have been in the rising phase and the second one in the decay phase.

  15. Complex dynamic scene perception: effects of attentional set on perceiving single and multiple event types.

    PubMed

    Sanocki, Thomas; Sulman, Noah

    2013-04-01

    Three experiments measured the efficiency of monitoring complex scenes composed of changing objects, or events. All events lasted about 4 s, but in a given block of trials, could be of a single type (single task) or of multiple types (multitask, with a total of four event types). Overall accuracy of detecting target events amid distractors was higher for single event types relative to multiple types. Multiple event types were processed reasonably well when each event type was restricted to its own region, and much worse when event types were mixed in location. In most task conditions, observers reached an optimal level of performance (optimal attentional set). After one target was identified, performance for other targets dropped markedly and then recovered to optimal levels. However, set was not optimized when task locations were intermixed. The results support the idea that attentional set determines the efficiency of event perception in complex scenes. Although single event set was most efficient, there can be a reasonably efficient set for multiple event types. PMID:23181683

  16. Semantic Complex Event Processing over End-to-End Data Flows

    SciTech Connect

    Zhou, Qunzhi; Simmhan, Yogesh; Prasanna, Viktor K.

    2012-04-01

    Emerging Complex Event Processing (CEP) applications in cyber physical systems like SmartPower Grids present novel challenges for end-to-end analysis over events, flowing from heterogeneous information sources to persistent knowledge repositories. CEP for these applications must support two distinctive features - easy specification patterns over diverse information streams, and integrated pattern detection over realtime and historical events. Existing work on CEP has been limited to relational query patterns, and engines that match events arriving after the query has been registered. We propose SCEPter, a semantic complex event processing framework which uniformly processes queries over continuous and archived events. SCEPteris built around an existing CEP engine with innovative support for semantic event pattern specification and allows their seamless detection over past, present and future events. Specifically, we describe a unified semantic query model that can operate over data flowing through event streams to event repositories. Compile-time and runtime semantic patterns are distinguished and addressed separately for efficiency. Query rewriting is examined and analyzed in the context of temporal boundaries that exist between event streams and their repository to avoid duplicate or missing results. The design and prototype implementation of SCEPterare analyzed using latency and throughput metrics for scenarios from the Smart Grid domain.

  17. Long-term transients and complex dynamics of a stage-structured population with time delay and the Allee effect.

    PubMed

    Morozov, A Yu; Banerjee, M; Petrovskii, S V

    2016-05-01

    Traditionally, mathematical modeling in population ecology is mainly focused on asymptotic behavior of the model, i.e. as given by the system attractors. Recently, however, transient regimes and especially long-term transients have been recognized as playing a crucial role in the dynamics of ecosystems. In particular, long-term transients are a potential explanation of ecological regime shifts, when an apparently healthy population suddenly collapses and goes extinct. In this paper, we show that the interplay between delay in maturation and a strong Allee effect can result in long-term transients in a single species system. We first derive a simple 'conceptual' model of the population dynamics that incorporates both a strong Allee effect and maturation delay. Unlike much of the previous work, our approach is not empirical since our model is derived from basic principles. We show that the model exhibits a high complexity in its asymptotic dynamics including multi-periodic and chaotic attractors. We then show the existence of long-term transient dynamics in the system, when the population size oscillates for a long time between locally stable stationary states before it eventually settles either at the persistence equilibrium or goes extinct. The parametric space of the model is found to have a complex structure with the basins of attraction corresponding to the persistence and extinction states being of a complicated shape. This impedes the prediction of the eventual fate of the population, as a small variation in the maturation delay or the initial population size can either bring the population to extinction or ensure its persistence. PMID:26921467

  18. Improving the extraction of complex regulatory events from scientific text by using ontology-based inference

    PubMed Central

    2011-01-01

    Background The extraction of complex events from biomedical text is a challenging task and requires in-depth semantic analysis. Previous approaches associate lexical and syntactic resources with ontologies for the semantic analysis, but fall short in testing the benefits from the use of domain knowledge. Results We developed a system that deduces implicit events from explicitly expressed events by using inference rules that encode domain knowledge. We evaluated the system with the inference module on three tasks: First, when tested against a corpus with manually annotated events, the inference module of our system contributes 53.2% of correct extractions, but does not cause any incorrect results. Second, the system overall reproduces 33.1% of the transcription regulatory events contained in RegulonDB (up to 85.0% precision) and the inference module is required for 93.8% of the reproduced events. Third, we applied the system with minimum adaptations to the identification of cell activity regulation events, confirming that the inference improves the performance of the system also on this task. Conclusions Our research shows that the inference based on domain knowledge plays a significant role in extracting complex events from text. This approach has great potential in recognizing the complex concepts of such biomedical ontologies as Gene Ontology in the literature. PMID:22166672

  19. An extended grammar system for learning and recognizing complex visual events.

    PubMed

    Zhang, Zhang; Tan, Tieniu; Huang, Kaiqi

    2011-02-01

    For a grammar-based approach to the recognition of visual events, there are two major limitations that prevent it from real application. One is that the event rules are predefined by domain experts, which means huge manual cost. The other is that the commonly used grammar can only handle sequential relations between subevents, which is inadequate to recognize more complex events involving parallel subevents. To solve these problems, we propose an extended grammar approach to modeling and recognizing complex visual events. First, motion trajectories as original features are transformed into a set of basic motion patterns of a single moving object, namely, primitives (terminals) in the grammar system. Then, a Minimum Description Length (MDL) based rule induction algorithm is performed to discover the hidden temporal structures in primitive stream, where Stochastic Context-Free Grammar (SCFG) is extended by Allen's temporal logic to model the complex temporal relations between subevents. Finally, a Multithread Parsing (MTP) algorithm is adopted to recognize interesting complex events in a given primitive stream, where a Viterbi-like error recovery strategy is also proposed to handle large-scale errors, e.g., insertion and deletion errors. Extensive experiments, including gymnastic exercises, traffic light events, and multi-agent interactions, have been executed to validate the effectiveness of the proposed approach. PMID:21193807

  20. High-speed observations of Transient Luminous Events and Lightning (The 2008/2009 Ebro Valley campaign)

    NASA Astrophysics Data System (ADS)

    Montanyà, Joan; van der Velde, Oscar; Soula, Serge; Romero, David; Pineda, Nicolau; Solà, Glòria; March, Víctor

    2010-05-01

    The future ASIM mission will provide x/y rays detections from space to investigate the origins of the Terrestrial Gamma-ray Flashes and its possible relation with transient luminous events (TLE). In order to support the future space observations we are setting up some ground infrastructure located at the Ebro Valley region (Northeast of Spain). At the end of 2008 and during 2009 we carried out our first observation campaign in order to acquire experience to support the future ASIM mission. From January 2008 to February 2009 we focused on the observation of TLE's with our intensified high-speed camera system. We recorded 14 sprites, 19 elves and, in three sprites, we observed also halos (Montanyà et al. 2009). Unfortunately no high-speed records of TLEs where observed in the range of the (XDDE) VHF network. However, we have recorded several tens of TLEs at normal frame rate (25 fps) which are in the XDDE range (Van der Velde et al., 2009). Additionally, in August 2009 we installed our first camera for TLE observation in the Caribean. The camera is located in San Andrés Isl. (Colombia). From June 2009 to October 2009 we focused all of our efforts to record lightning at high-speed (10000 fps), vertical close electric fields and x-ray emissions from lightning. We recorded around 60 lightning flashes but we only clearly evidenced high energy detections in only one flash. The detections were produced during the leader phase of a cloud-to-ground flash. The leader signature on the recorded electric field was very short (around 1 ms) and, during this period, a burst of high energy emissions where detected. Then, few detections where produced just after the return stroke. The experience of this preliminary campaign has given us the basis for the future campaigns where we plan to count with two high-speed cameras and a Lightning Mapping Array. References Montanyà et al. (2009). High-Speed Intensified Video Recordings of Sprites and Elves over the Western Mediterranean Sea

  1. Complex active regions as the main source of extreme and large solar proton events

    NASA Astrophysics Data System (ADS)

    Ishkov, V. N.

    2013-12-01

    A study of solar proton sources indicated that solar flare events responsible for ≥2000 pfu proton fluxes mostly occur in complex active regions (CARs), i.e., in transition structures between active regions and activity complexes. Different classes of similar structures and their relation to solar proton events (SPEs) and evolution, depending on the origination conditions, are considered. Arguments in favor of the fact that sunspot groups with extreme dimensions are CARs are presented. An analysis of the flare activity in a CAR resulted in the detection of "physical" boundaries, which separate magnetic structures of the same polarity and are responsible for the independent development of each structure.

  2. Statistical searches for microlensing events in large, non-uniformly sampled time-domain surveys: A test using palomar transient factory data

    SciTech Connect

    Price-Whelan, Adrian M.; Agüeros, Marcel A.; Fournier, Amanda P.; Street, Rachel; Ofek, Eran O.; Covey, Kevin R.; Levitan, David; Sesar, Branimir; Laher, Russ R.; Surace, Jason

    2014-01-20

    Many photometric time-domain surveys are driven by specific goals, such as searches for supernovae or transiting exoplanets, which set the cadence with which fields are re-imaged. In the case of the Palomar Transient Factory (PTF), several sub-surveys are conducted in parallel, leading to non-uniform sampling over its ∼20,000 deg{sup 2} footprint. While the median 7.26 deg{sup 2} PTF field has been imaged ∼40 times in the R band, ∼2300 deg{sup 2} have been observed >100 times. We use PTF data to study the trade off between searching for microlensing events in a survey whose footprint is much larger than that of typical microlensing searches, but with far-from-optimal time sampling. To examine the probability that microlensing events can be recovered in these data, we test statistics used on uniformly sampled data to identify variables and transients. We find that the von Neumann ratio performs best for identifying simulated microlensing events in our data. We develop a selection method using this statistic and apply it to data from fields with >10 R-band observations, 1.1 × 10{sup 9} light curves, uncovering three candidate microlensing events. We lack simultaneous, multi-color photometry to confirm these as microlensing events. However, their number is consistent with predictions for the event rate in the PTF footprint over the survey's three years of operations, as estimated from near-field microlensing models. This work can help constrain all-sky event rate predictions and tests microlensing signal recovery in large data sets, which will be useful to future time-domain surveys, such as that planned with the Large Synoptic Survey Telescope.

  3. Complex Rotating Waves and Long Transients in a Ring Network of Electrochemical Oscillators with Sparse Random Cross-Connections.

    PubMed

    Sebek, Michael; Tönjes, Ralf; Kiss, István Z

    2016-02-12

    We perform experiments and phase model simulations with a ring network of oscillatory electrochemical reactions to explore the effect of random connections and nonisochronicity of the interactions on the pattern formation. A few additional links facilitate the emergence of the fully synchronized state. With larger nonisochronicity, complex rotating waves or persistent irregular phase dynamics can derail the convergence to global synchronization. The observed long transients of irregular phase dynamics exemplify the possibility of a sudden onset of hypersynchronous behavior without any external stimulus or network reorganization. PMID:26919024

  4. Effects of Grammaticality and Morphological Complexity on the P600 Event-Related Potential Component

    PubMed Central

    Wampler, Emma K.; Valentine, Geoffrey D.; Osterhout, Lee

    2015-01-01

    We investigated interactions between morphological complexity and grammaticality on electrophysiological markers of grammatical processing during reading. Our goal was to determine whether morphological complexity and stimulus grammaticality have independent or additive effects on the P600 event-related potential component. Participants read sentences that were either well-formed or grammatically ill-formed, in which the critical word was either morphologically simple or complex. Results revealed no effects of complexity for well-formed stimuli, but the P600 amplitude was significantly larger for morphologically complex ungrammatical stimuli than for morphologically simple ungrammatical stimuli. These findings suggest that some previous work may have inadequately characterized factors related to reanalysis during morphosyntactic processing. Our results show that morphological complexity by itself does not elicit P600 effects. However, in ungrammatical circumstances, overt morphology provides a more robust and reliable cue to morphosyntactic relationships than null affixation. PMID:26488893

  5. Everyday Matters in Science and Mathematics: Studies of Complex Classroom Events

    ERIC Educational Resources Information Center

    Nemirovsky, Ricardo, Ed.; Rosebery, Ann S., Ed.; Solomon, Jesse, Ed.; Warren, Beth, Ed.

    2005-01-01

    This book re-examines the dichotomy between the everyday and the disciplinary in mathematics and science education, and explores alternatives to this opposition from points of view grounded in the close examination of complex classroom events. It makes the case that students' everyday experience and knowledge in their entire manifold forms matter…

  6. Single Event Testing on Complex Devices: Test Like You Fly Versus Test-Specific Design Structures

    NASA Technical Reports Server (NTRS)

    Berg, Melanie D.; Label, Kenneth

    2016-01-01

    We present a mechanism for evaluating complex digital systems targeted for harsh radiation environments such as space. Focus is limited to analyzing the single event upset (SEU) susceptibility of designs implemented inside Field Programmable Gate Array (FPGA) devices. Tradeoffs are provided between application-specific versus test-specific test structures.

  7. The role of auditory transient and deviance processing in distraction of task performance: a combined behavioral and event-related brain potential study.

    PubMed

    Berti, Stefan

    2013-01-01

    Distraction of goal-oriented performance by a sudden change in the auditory environment is an everyday life experience. Different types of changes can be distracting, including a sudden onset of a transient sound and a slight deviation of otherwise regular auditory background stimulation. With regard to deviance detection, it is assumed that slight changes in a continuous sequence of auditory stimuli are detected by a predictive coding mechanisms and it has been demonstrated that this mechanism is capable of distracting ongoing task performance. In contrast, it is open whether transient detection-which does not rely on predictive coding mechanisms-can trigger behavioral distraction, too. In the present study, the effect of rare auditory changes on visual task performance is tested in an auditory-visual cross-modal distraction paradigm. The rare changes are either embedded within a continuous standard stimulation (triggering deviance detection) or are presented within an otherwise silent situation (triggering transient detection). In the event-related brain potentials, deviants elicited the mismatch negativity (MMN) while transients elicited an enhanced N1 component, mirroring pre-attentive change detection in both conditions but on the basis of different neuro-cognitive processes. These sensory components are followed by attention related ERP components including the P3a and the reorienting negativity (RON). This demonstrates that both types of changes trigger switches of attention. Finally, distraction of task performance is observable, too, but the impact of deviants is higher compared to transients. These findings suggest different routes of distraction allowing for the automatic processing of a wide range of potentially relevant changes in the environment as a pre-requisite for adaptive behavior. PMID:23874278

  8. Event-triggered synchronization strategy for complex dynamical networks with the Markovian switching topologies.

    PubMed

    Wang, Aijuan; Dong, Tao; Liao, Xiaofeng

    2016-02-01

    This paper concerns the synchronization problem of complex networks with the random switching topologies. By modeling the switching of network topologies as a Markov process, a novel event-triggered synchronization strategy is proposed. Unlike the existing strategies, the event detection of this strategy only works at the network topology switching time instant, which can significantly decrease the communication frequency between nodes and save the network resources. Under this strategy, the synchronization problem of complex network is equivalently converted to the stability of a class of Markovian jump systems with a time-varying delay. By using the Lyapunov-Krasovskii functional method and the weak infinitesimal operation, a sufficient condition for the mean square synchronization of the complex networks subject to Markovian switching topologies is established. Finally, a numerical simulation example is provided to demonstrate the theoretical results. PMID:26650712

  9. Transient suppression of broadband gamma power in the default-mode network is correlated with task complexity and subject performance.

    PubMed

    Ossandón, Tomas; Jerbi, Karim; Vidal, Juan R; Bayle, Dimitri J; Henaff, Marie-Anne; Jung, Julien; Minotti, Lorella; Bertrand, Olivier; Kahane, Philippe; Lachaux, Jean-Philippe

    2011-10-12

    Task performance is associated with increased brain metabolism but also with prominent deactivation in specific brain structures known as the default-mode network (DMN). The role of DMN deactivation remains enigmatic in part because its electrophysiological correlates, temporal dynamics, and link to behavior are poorly understood. Using extensive depth electrode recordings in humans, we provide first electrophysiological evidence for a direct correlation between the dynamics of power decreases in the DMN and individual subject behavior. We found that all DMN areas displayed transient suppressions of broadband gamma (60-140 Hz) power during performance of a visual search task and, critically, we show for the first time that the millisecond range duration and extent of the transient gamma suppressions are correlated with task complexity and subject performance. In addition, trial-by-trial correlations revealed that spatially distributed gamma power increases and decreases formed distinct anticorrelated large-scale networks. Beyond unraveling the electrophysiological basis of DMN dynamics, our results suggest that, rather than indicating a mere switch to a global exteroceptive mode, DMN deactivation encodes the extent and efficiency of our engagement with the external world. Furthermore, our findings reveal a pivotal role for broadband gamma modulations in the interplay between task-positive and task-negative networks mediating efficient goal-directed behavior and facilitate our understanding of the relationship between electrophysiology and neuroimaging studies of intrinsic brain networks. PMID:21994368

  10. Complex Biological Event Extraction from Full Text using Signatures of Linguistic and Semantic Features

    SciTech Connect

    McGrath, Liam R.; Domico, Kelly O.; Corley, Courtney D.; Webb-Robertson, Bobbie-Jo M.

    2011-06-24

    Building on technical advances from the BioNLP 2009 Shared Task Challenge, the 2011 challenge sets forth to generalize techniques to other complex biological event extraction tasks. In this paper, we present the implementation and evaluation of a signature-based machine-learning technique to predict events from full texts of infectious disease documents. Specifically, our approach uses novel signatures composed of traditional linguistic features and semantic knowledge to predict event triggers and their candidate arguments. Using a leave-one out analysis, we report the contribution of linguistic and shallow semantic features in the trigger prediction and candidate argument extraction. Lastly, we examine evaluations and posit causes for errors of infectious disease track subtasks.

  11. Determination of transport and reaction swarm coefficients from the analysis of complex transient pulses from the pulsed Townsend experiment

    NASA Astrophysics Data System (ADS)

    Bekstein, A.; de Urquijo, J.; Ducasse, O.; Rodríguez-Luna, J. C.; Juárez, A. M.

    2012-06-01

    We present in this paper the interpretation and analysis of transient pulses from a pulsed Townsend experiment by solving the continuity equations of the charged carriers (electrons and ions) involved in the avalanche. The set of second order partial differential equations is solved by SIMAV, a simulator designed specifically for the pulsed Townsend avalanche. Complex situations involving processes such as electron detachment, ion-molecule reactions, Penning ionization and secondary electron emission from ion impact at the cathode, virtually impossible to solve analytically, are discussed here to illustrate the capability of the simulator to help explain the various reaction processes involved in the avalanche, and also to derive some of the transport and reaction coefficients.

  12. Characterization of Complex Systems Using the Design of Experiments Approach: Transient Protein Expression in Tobacco as a Case Study

    PubMed Central

    Buyel, Johannes Felix; Fischer, Rainer

    2014-01-01

    Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the additional advantage of short development and production times, but expression levels can vary significantly between batches thus giving rise to regulatory concerns in the context of good manufacturing practice. We used a design of experiments (DoE) approach to determine the impact of major factors such as regulatory elements in the expression construct, plant growth and development parameters, and the incubation conditions during expression, on the variability of expression between batches. We tested plants expressing a model anti-HIV monoclonal antibody (2G12) and a fluorescent marker protein (DsRed). We discuss the rationale for selecting certain properties of the model and identify its potential limitations. The general approach can easily be transferred to other problems because the principles of the model are broadly applicable: knowledge-based parameter selection, complexity reduction by splitting the initial problem into smaller modules, software-guided setup of optimal experiment combinations and step-wise design augmentation. Therefore, the methodology is not only useful for characterizing protein expression in plants but also for the investigation of other complex systems lacking a mechanistic description. The predictive equations describing the interconnectivity between parameters can be used to establish mechanistic models for other complex systems. PMID:24514765

  13. Self-Structures, Negative Events, and Adolescent Depression: Clarifying the Role of Self-Complexity in a Prospective, Multiwave Study

    ERIC Educational Resources Information Center

    Cohen, Joseph R.; Spiegler, Kevin M.; Young, Jami F.; Hankin, Benjamin L.; Abela, John R. Z.

    2014-01-01

    The purpose of this multiwave longitudinal study was to examine the structure of self-complexity and its relation to depressive symptoms in 276 adolescents (M = 12.55; SD = 1.04). Self-complexity, depressive symptoms, and negative events were assessed during a laboratory assessment at baseline, and then depressive symptoms and negative events were…

  14. Psychological distress and stressful life events in pediatric complex regional pain syndrome

    PubMed Central

    Wager, Julia; Brehmer, Hannah; Hirschfeld, Gerrit; Zernikow, Boris

    2015-01-01

    BACKGROUND: There is little knowledge regarding the association between psychological factors and complex regional pain syndrome (CRPS) in children. Specifically, it is not known which factors precipitate CRPS and which result from the ongoing painful disease. OBJECTIVES: To examine symptoms of depression and anxiety as well as the experience of stressful life events in children with CRPS compared with children with chronic primary headaches and functional abdominal pain. METHODS: A retrospective chart study examined children with CRPS (n=37) who received intensive inpatient pain treatment between 2004 and 2010. They were compared with two control groups (chronic primary headaches and functional abdominal pain; each n=37), who also received intensive inpatient pain treatment. Control groups were matched with the CRPS group with regard to admission date, age and sex. Groups were compared on symptoms of depression and anxiety as well as stressful life events. RESULTS: Children with CRPS reported lower anxiety and depression scores compared with children with abdominal pain. A higher number of stressful life events before and after the onset of the pain condition was observed for children with CRPS. CONCLUSIONS: Children with CRPS are not particularly prone to symptoms of anxiety or depression. Importantly, children with CRPS experienced more stressful life events than children with chronic headaches or abdominal pain. Prospective long-term studies are needed to further explore the potential role of stressful life events in the etiology of CRPS. PMID:26035287

  15. Field in a complex cylindrical/coaxial cavity subject to time-harmonic and transient excitation

    NASA Astrophysics Data System (ADS)

    Bopp, Charles L.; Butler, Chalmers M.

    2004-12-01

    A coupled integral-equation method for calculating fields in complex cavities is developed and is applied to cavities comprising multiple cascaded and overlapping coaxial and circular-cylindrical regions or sections. The field in a section is related to the fields in apertures of planar conducting surfaces, which bound the section. Laboratory cavities are constructed, and their fields are computed from numerical solutions of the integral equations. The results are compared with data obtained through measurements in both the frequency and time domains. The accuracy of the method is also verified by comparison of measured and calculated values of the current and charge on cavity walls. The tools developed are used to investigate the salient features of a sine burst that passes through the complex cavity.

  16. Comparison of Single-Event Transients Induced in an Operational Amplifier (LM124) by Pulsed Laser Light and a Broad Beam of Heavy Ions

    NASA Technical Reports Server (NTRS)

    Buchner, Steve; McMorrow, Dale; Poivey, Christian; Howard, James, Jr.; Pease, Rom; Savage, Mark; Boulghassoul, Younis; Massengill, Lloyd

    2003-01-01

    A comparison of transients from heavy-ion and pulsed-laser testing shows good agreement for many different voltage configurations. The agreement is illustrated by comparing directly individual transients and plots of transient amplitude versus width.

  17. A numerical approach for pressure transient analysis of a vertical well with complex fractures

    NASA Astrophysics Data System (ADS)

    Wan, Yizhao; Liu, Yuewu; Liu, Wenchao; Han, Guofeng; Niu, Congcong

    2016-05-01

    A new well test model for a vertical fractured well is developed based on a discrete-fracture model in which the fractures are discretized as one dimensional (1-D) entities. The model overcomes the weakness of complex meshing, a large number of grids, and instability in conventional stripe-fracture models. Then, the discrete-fracture model is implemented using a hybrid element finite-element method. Triangular elements are used for matrix and line elements for the fractures. The finite element formulation is validated by comparing with the semi-analytical solution of a single vertical fractured well. The accuracy of the approach is shown through several examples with different fracture apertures, fracture conductivity, and fracture amount. Results from the discrete-fracture model agree reasonably well with the stripe-fracture model and the analytic solutions. The advantages of the discrete-fracture model are presented in mesh generation, computational improvement, and abilities to handle complex fractures like wedge-shaped fractures and fractures with branches. Analytical results show that the number of grids in the discrete-fracture model is 10 % less than stripe-fracture model, and computational efficiency increases by about 50 %. The more fractures there are, the more the computational efficiency increases.

  18. Ligand-induced formation of a transient tryptophan synthase complex with αββ subunit stoichiometry.

    PubMed

    Ehrmann, Alexander; Richter, Klaus; Busch, Florian; Reimann, Julia; Albers, Sonja-Verena; Sterner, Reinhard

    2010-12-28

    The prototypical tryptophan synthases form a stable heterotetrameric αββα complex in which the constituting TrpA and TrpB1 subunits activate each other in a bidirectional manner. The hyperthermophilic archaeon Sulfolobus solfataricus does not contain a TrpB1 protein but instead two members of the phylogenetically distinct family of TrpB2 proteins, which are encoded within (sTrpB2i) and outside (sTrpB2a) the tryptophan operon. It has previously been shown that sTrpB2a does not functionally or structurally interact with sTrpA, whereas sTrpB2i substantially activates sTrpA in a unidirectional manner. However, in the absence of catalysis, no physical complex between sTrpB2i and sTrpA could be detected. In order to elucidate the structural requirements for complex formation, we have analyzed the interaction between sTrpA (α-monomer) and sTrpB2i (ββ-dimer) by means of spectroscopy, analytical gel filtration, and analytical ultracentrifugation, as well as isothermal titration calorimetry. In the presence of the TrpA ligand glycerol 3-phosphate (GP) and the TrpB substrate l-serine, sTrpA and sTrpB2i formed a physical complex with a thermodynamic dissociation constant of about 1 μM, indicating that the affinity between the α- and ββ-subunits is weaker by at least 1 order of magnitude than the affinity between the corresponding subunits of prototypical tryptophan synthases. The observed stoichiometry of the complex was 1 subunit of sTrpA per 2 subunits of sTrpB2i, which corresponds to a αββ quaternary structure and testifies to a strong negative cooperativity for the binding of the α-monomers to the ββ-dimer. The analysis of the interaction between sTrpB2i and sTrpA in the presence of several substrate, transition state, and product analogues suggests that the αββ complex remains stable during the whole catalytic cycle and disintegrates into α- and ββ-subunits upon the release of the reaction product tryptophan. The formation of a transient tryptophan

  19. Complex Events Initiated by Individual Spikes in the Human Cerebral Cortex

    PubMed Central

    Komlósi, Gergely; Füle, Miklós; Szabadics, János; Varga, Csaba; Barzó, Pál; Tamás, Gábor

    2008-01-01

    Synaptic interactions between neurons of the human cerebral cortex were not directly studied to date. We recorded the first dataset, to our knowledge, on the synaptic effect of identified human pyramidal cells on various types of postsynaptic neurons and reveal complex events triggered by individual action potentials in the human neocortical network. Brain slices were prepared from nonpathological samples of cortex that had to be removed for the surgical treatment of brain areas beneath association cortices of 58 patients aged 18 to 73 y. Simultaneous triple and quadruple whole-cell patch clamp recordings were performed testing mono- and polysynaptic potentials in target neurons following a single action potential fired by layer 2/3 pyramidal cells, and the temporal structure of events and underlying mechanisms were analyzed. In addition to monosynaptic postsynaptic potentials, individual action potentials in presynaptic pyramidal cells initiated long-lasting (37 ± 17 ms) sequences of events in the network lasting an order of magnitude longer than detected previously in other species. These event series were composed of specifically alternating glutamatergic and GABAergic postsynaptic potentials and required selective spike-to-spike coupling from pyramidal cells to GABAergic interneurons producing concomitant inhibitory as well as excitatory feed-forward action of GABA. Single action potentials of human neurons are sufficient to recruit Hebbian-like neuronal assemblies that are proposed to participate in cognitive processes. PMID:18767905

  20. Inhibition of selective signaling events in natural killer cells recognizing major histocompatibility complex class I.

    PubMed Central

    Kaufman, D S; Schoon, R A; Robertson, M J; Leibson, P J

    1995-01-01

    Many studies have characterized the transmembrane signaling events initiated after T-cell antigen receptor recognition of major histocompatibility complex (MHC)-bound peptides. Yet, little is known about signal transduction from a set of MHC class I recognizing receptors on natural killer (NK) cells whose ligation dramatically inhibits NK cell-mediated killing. In this study we evaluated the influence of MHC recognition on the proximal signaling events in NK cells binding tumor targets. We utilized two experimental models where NK cell-mediated cytotoxicity was fully inhibited by the recognition of specific MHC class I molecules. NK cell binding to either class I-deficient or class I-transfected target cells initiated rapid protein tyrosine kinase activation. In contrast, whereas NK cell binding to class I-deficient targets led to inositol phosphate release and increased intracellular free calcium ([Ca2+]i), NK recognition of class I-bearing targets did not induce the activation of these phospholipase C-dependent signaling events. The recognition of class I by NK cells clearly had a negative regulatory effect since blocking this interaction using anti-class I F(ab')2 fragments increased inositol 1,4,5-trisphosphate release and [Ca2+]i and increased the lysis of the targets. These results suggest that one of the mechanisms by which NK cell recognition of specific MHC class I molecules can block the development of cell-mediated cytotoxicity is by inhibiting specific critical signaling events. Images Fig. 2 Fig. 4 PMID:7604018

  1. Peclet number as affected by molecular diffusion controls transient anomalous transport in alluvial aquifer-aquitard complexes.

    PubMed

    Zhang, Yong; Green, Christopher T; Tick, Geoffrey R

    2015-01-01

    This study evaluates the role of the Peclet number as affected by molecular diffusion in transient anomalous transport, which is one of the major knowledge gaps in anomalous transport, by combining Monte Carlo simulations and stochastic model analysis. Two alluvial settings containing either short- or long-connected hydrofacies are generated and used as media for flow and transport modeling. Numerical experiments show that 1) the Peclet number affects both the duration of the power-law segment of tracer breakthrough curves (BTCs) and the transition rate from anomalous to Fickian transport by determining the solute residence time for a given low-permeability layer, 2) mechanical dispersion has a limited contribution to the anomalous characteristics of late-time transport as compared to molecular diffusion due to an almost negligible velocity in floodplain deposits, and 3) the initial source dimensions only enhance the power-law tail of the BTCs at short travel distances. A tempered stable stochastic (TSS) model is then applied to analyze the modeled transport. Applications show that the time-nonlocal parameters in the TSS model relate to the Peclet number, Pe. In particular, the truncation parameter in the TSS model increases nonlinearly with a decrease in Pe due to the decrease of the mean residence time, and the capacity coefficient increases with an increase in molecular diffusion which is probably due to the increase in the number of immobile particles. The above numerical experiments and stochastic analysis therefore reveal that the Peclet number as affected by molecular diffusion controls transient anomalous transport in alluvial aquifer-aquitard complexes. PMID:26001981

  2. Peclet number as affected by molecular diffusion controls transient anomalous transport in alluvial aquifer-aquitard complexes

    USGS Publications Warehouse

    Zhang, Yong; Green, Christopher T.; Tick, Geoffrey R.

    2015-01-01

    This study evaluates the role of the Peclet number as affected by molecular diffusion in transient anomalous transport, which is one of the major knowledge gaps in anomalous transport, by combining Monte Carlo simulations and stochastic model analysis. Two alluvial settings containing either short- or long-connected hydrofacies are generated and used as media for flow and transport modeling. Numerical experiments show that 1) the Peclet number affects both the duration of the power-law segment of tracer breakthrough curves (BTCs) and the transition rate from anomalous to Fickian transport by determining the solute residence time for a given low-permeability layer, 2) mechanical dispersion has a limited contribution to the anomalous characteristics of late-time transport as compared to molecular diffusion due to an almost negligible velocity in floodplain deposits, and 3) the initial source dimensions only enhance the power-law tail of the BTCs at short travel distances. A tempered stable stochastic (TSS) model is then applied to analyze the modeled transport. Applications show that the time-nonlocal parameters in the TSS model relate to the Peclet number, Pe. In particular, the truncation parameter in the TSS model increases nonlinearly with a decrease in Pe due to the decrease of the mean residence time, and the capacity coefficient increases with an increase in molecular diffusion which is probably due to the increase in the number of immobile particles. The above numerical experiments and stochastic analysis therefore reveal that the Peclet number as affected by molecular diffusion controls transient anomalous transport in alluvial aquifer–aquitard complexes.

  3. Acoustic properties of the full spectrum of stick-slip events from stable sliding to dynamic rupture: insights on the mechanics of slow earthquakes and transient fault slip.

    NASA Astrophysics Data System (ADS)

    Scuderi, M. M.; Marone, C.; Tinti, E.; Di Stefano, G.; Collettini, C.

    2015-12-01

    Seismic and geodetic observations show that fault slip occurs via a spectrum of behaviors that include slow earthquakes and tectonic tremor. These phenomena have been observed in a variety of tectonic environments worldwide, however the underlying processes are poorly understood. Here we report on lab experiments on simulated fault gouge. We used the double direct shear configuration and varied the loading system stiffness (k) to produce the full spectrum of stick-slip behaviors, with durations ranging from 10-3 to 1 second. We measured frictional rheology and elastic wave properties throughout the stick-slip cycle for slow and fast events. When the loading stiffness is greater than the fault zone critical rheologic stiffness (kc) we observe stable frictional sliding. For k≈kc we document emergent slow-slip events from steady shear. When kc>k we observe audible stick-slip. Stick slip stress drop and event duration vary systematically as a function of the ratio k/kc. For slow-slip events, p-wave velocity (Vp) begins to decrease prior to the stress drop and the maximum slip velocity during failure coincides with the largest drop in Vp. Dynamic stick-slip events do not show precursory changes in Vp prior to failure. We find that fault creep and precursory changes in wave properties vary systematically with stick-slip event duration, with slower events showing larger precursory changes. In general, Vp begins to decrease prior to failure and drops abruptly as slip velocity accelerates to a peak value. The drop in Vp appears to be larger during dynamic stick-slip than for slow-slip events. Our results suggest that slow earthquakes and transient fault slip are governed by the same frictional processes as dynamic stick-slip and represent a continuum in the spectrum of fault slip. We show that fault gouge elastic properties evolve during the pre-seismic stage of slow-slip, which could provide an important means of assessing short term seismic hazard.

  4. Computed Tomography Imaging Spectrometer (CTIS) with 2D Reflective Grating for Ultraviolet to Long-Wave Infrared Detection Especially Useful for Surveying Transient Events

    NASA Technical Reports Server (NTRS)

    Wilson, Daniel W. (Inventor); Maker, Paul D. (Inventor); Muller, Richard E. (Inventor); Mouroulis, Pantazis Z. (Inventor)

    2003-01-01

    The optical system of this invention is an unique type of imaging spectrometer, i.e. an instrument that can determine the spectra of all points in a two-dimensional scene. The general type of imaging spectrometer under which this invention falls has been termed a computed-tomography imaging spectrometer (CTIS). CTIS's have the ability to perform spectral imaging of scenes containing rapidly moving objects or evolving features, hereafter referred to as transient scenes. This invention, a reflective CTIS with an unique two-dimensional reflective grating, can operate in any wavelength band from the ultraviolet through long-wave infrared. Although this spectrometer is especially useful for events it is also for investigation of some slow moving phenomena as in the life sciences.

  5. Computed tomography imaging spectrometer (CTIS) with 2D reflective grating for ultraviolet to long-wave infrared detection especially useful for surveying transient events

    NASA Technical Reports Server (NTRS)

    Wilson, Daniel W. (Inventor); Maker, Paul D. (Inventor); Muller, Richard E. (Inventor); Mouroulis, Pantazis Z. (Inventor)

    2003-01-01

    The optical system of this invention is an unique type of imaging spectrometer, i.e. an instrument that can determine the spectra of all points in a two-dimensional scene. The general type of imaging spectrometer under which this invention falls has been termed a computed-tomography imaging spectrometer (CTIS). CTIS's have the ability to perform spectral imaging of scenes containing rapidly moving objects or evolving features, hereafter referred to as transient scenes. This invention, a reflective CTIS with an unique two-dimensional reflective grating, can operate in any wavelength band from the ultraviolet through long-wave infrared. Although this spectrometer is especially useful for rapidly occurring events it is also useful for investigation of some slow moving phenomena as in the life sciences.

  6. Transient attenuation of the amplitude of the QRS complexes in the diagnosis of Takotsubo syndrome

    PubMed Central

    2014-01-01

    Background and objectives: Currently, there are no specific diagnostic electrocardiogram (ECG) signs for Takotsubo syndrome (TTS) to differentiate it from acute coronary syndromes (ACS). Myocardial oedema has been detected by cardiac magnetic resonance imaging in patients with TTS. Recently it has been postulated that myocardial oedema may be the cause of low QRS voltage (LQRSV) in the admission ECG and attenuation of the amplitude of the QRS complexes (AAQRS) in serial ECGs, noted in a few published cases of patients with TTS. The objective of this study was to evaluate whether the admission ECG of patients with documented TTS reveals LQRSV and whether AAQRS is found when serial ECGs are compared in such patients. Methods: This study evaluated the prevalence of LQRSV in the admission ECG and AAQRS in serial ECGs in patients with TTS. ECGs of 368 patients with TTS from published reports in the international literature were evaluated for LQRSV (≤5 mm in limb leads and/or ≤10 mm in precordial leads) and AAQRS in serial ECGs. Results: LQRSV was seen in 91.5% of 200 patients with TTS and one ECG, with a distribution of 49.0, 42.8, 51.0, 52.0, and 46.9%, in lead aVR, and inferior, anterior, lateral, and high lateral ECG lead groups, respectively. AAQRS was seen in 93.5% of 168 patients with TTS and two or more ECGs, with a distribution of 78.3, 74.5, 60.1, 70.7, and 74.5% in lead aVR, and inferior, anterior, lateral, and high lateral ECG lead groups, respectively. Conclusions: LQRSV and AAQRS are highly prevalent ECG signs in patients with TTS, and should be useful in aiding in its diagnosis and differentiation from ACS, on first contact with the patient on admission to the hospital, and the ensuing 24 hours, in conjunction with echocardiography and coronary arteriography. PMID:24562801

  7. POP-ART: thermodynamically correct activated event sampling in complex materials

    NASA Astrophysics Data System (ADS)

    Chubynsky, M. V.; Vocks, Henk; Mousseau, Normand; Barkema, G. T.

    2006-03-01

    Dynamics of complex systems with a rugged energy landscape can be represented as a sequence of rare activated events during which the system jumps between different potential energy minima. The activation-relaxation technique (ART) [1] is an efficient method of sampling such events; however, because of an unknown bias in selecting these events it cannot easily provide thermodynamical information. We present a modification of ART, the properly obeying probability ART (POP-ART) [2]. POP-ART combines short molecular dynamics runs with ART-like activated moves, with an additional accept/reject step designed to satisfy detailed balance and thus reproduce correct thermodynamics. Both correctness and efficiency of the method have been tested using a variety of systems. We mention briefly some ways of extending the approach to obtain correct dynamics as well.[1] G.T. Barkema and N. Mousseau, Phys. Rev. Lett. 77, 4358 (1996)[2] H. Vocks, M.V. Chubynsky, G.T. Barkema and N. Mousseau, J. Chem. Phys., accepted

  8. Spectral signatures of penumbral transients

    SciTech Connect

    Reardon, K.; Tritschler, A.

    2013-12-20

    In this work we investigate the properties of penumbral transients observed in the upper photospheric and chromospheric region above a sunspot penumbra using two-dimensional spectroscopic observations of the Ca II 854.21 nm line with a 5 s cadence. In our 30 minutes of observations, we identify several penumbral-micro jets (PMJs) with cotemporal observations from Dunn Solar Telescope/IBIS and Hinode/SOT. We find that the line profiles of these PMJ events show emission in the two wings of the line (±0.05 nm), but little modification of the line core. These are reminiscent of the line profiles of Ellerman bombs observed in plage and network regions. Furthermore, we find evidence that some PMJ events have a precursor phase starting 1 minute prior to the main brightening that might indicate initial heating of the plasma prior to an acoustic or bow shock event. With the IBIS data, we also find several other types of transient brightenings with timescales of less than 1 minute that are not clearly seen in the Hinode/SOT data. The spectral profiles and other characteristics of these events are significantly different from those of PMJs. The different appearances of all these transients are an indicator of the general complexity of the chromospheric magnetic field and underscore the highly dynamic behavior above sunspots. It also highlights the care that is needed in interpreting broadband filter images of chromospheric lines, which may conceal very different spectral profiles, and the underlying physical mechanisms at work.

  9. Expression and cellular distribution of transient receptor potential vanilloid 4 in cortical tubers of the tuberous sclerosis complex.

    PubMed

    Chen, Xin; Yang, Meihua; Sun, Feiji; Liang, Chao; Wei, Yujia; Wang, Lukang; Yue, Jiong; Chen, Bing; Li, Song; Liu, Shiyong; Yang, Hui

    2016-04-01

    Cortical tubers in patients with tuberous sclerosis complex (TSC) are highly associated with intractable epilepsy. Recent evidence has shown that transient receptor potential vanilloid 4 (TRPV4) has direct effects on both neurons and glial cells. To understand the role of TRPV4 in pathogenesis of cortical tubers, we investigated the expression patterns of TRPV4 in cortical tubers of TSC compared with normal control cortex (CTX). We found that TRPV4 was clearly up-regulated in cortical tubers at the protein levels. Immunostaining indicated that TRPV4 was specially distributed in abnormal cells, including dysplastic neurons (DNs) and giant cells (GCs). In addition, double immunofluorescent staining revealed that TRPV4 was localized on neurofilament proteins (NF200) positive neurons and glial fibrillary acidic portein (GFAP) positive reactive astrocytes. Moreover, TRPV4 co-localized with both glutamatergic and GABAergic neurons. Furthermore, protein levels of protein kinase C (PKC), but not protein kinase A (PKA), the important upstream factors of the TRPV4, were significantly increased in cortical tubers. Taken together, the overexpression and distribution patterns of TRPV4 may be linked with the intractable epilepsy caused by TSC. PMID:26874068

  10. Comparative research on “high currents” induced by single event latch-up and transient-induced latch-up

    NASA Astrophysics Data System (ADS)

    Chen, Rui; Han, Jian-Wei; Zheng, Han-Sheng; Yu, Yong-Tao; Shangguang, Shi-Peng; Feng, Guo-Qiang; Ma, Ying-Qi

    2015-04-01

    By using the pulsed laser single event effect facility and electro-static discharge (ESD) test system, the characteristics of the “high current”, relation with external stimulus and relevance to impacted modes of single event latch-up (SEL) and transient-induced latch-up (TLU) are studied, respectively, for a 12-bit complementary metal-oxide semiconductor (CMOS) analog-to-digital converter. Furthermore, the sameness and difference in physical mechanism between “high current” induced by SEL and that by TLU are disclosed in this paper. The results show that the minority carrier diffusion in the PNPN structure of the CMOS device which initiates the active parasitic NPN and PNP transistors is the common reason for the “high current” induced by SEL and for that by TLU. However, for SEL, the minority carrier diffusion is induced by the ionizing radiation, and an underdamped sinusoidal voltage on the supply node (the ground node) is the cause of the minority carrier diffusion for TLU. Project supported by the National Natural Science Foundation of China (Grant No. 41304148).

  11. The background rate of false positives: Combining simulations of gravitational wave events with an unsupervised algorithm for transient identification in crowded image-subtracted data

    NASA Astrophysics Data System (ADS)

    Ackley, Kendall; Eikenberry, Stephen; Klimenko, Sergey; LIGO Collaboration

    2016-03-01

    We are now entering the era of multimessenger gravitational wave (GW) astronomy with the completion of the first observing run of Advanced LIGO. Multiwavelength electromagnetic (EM) emission is expected to accompany gravitational radiation from compact object binary mergers, such as those between neutron stars and stellar-mass black holes, where Advanced LIGO is most sensitive to their detection. Attempting to perform EM follow-up over the 10-100s deg2 error regions will be faced with many challenges, including the identification and removal of O (105) false positive transients that appear as a commotion of background events and as image artifacts in crowded image-subtracted fields. We present an update to our automated unsupervised algorithm including how our pipeline uses the existing coherent WaveBurst pipeline in an attempt to develop optimized EM follow-up schema. Our end-to-end pipeline combines simulated GW events with actual observational data from a number of ground-based optical observatories, including PTF, ROTSE, and DECam. Our performance is reported both in terms of the number of coincident false positives as well as the efficiency of recovery.

  12. Prenatal complex rhythmic music sound stimulation facilitates postnatal spatial learning but transiently impairs memory in the domestic chick.

    PubMed

    Kauser, H; Roy, S; Pal, A; Sreenivas, V; Mathur, R; Wadhwa, S; Jain, S

    2011-01-01

    Early experience has a profound influence on brain development, and the modulation of prenatal perceptual learning by external environmental stimuli has been shown in birds, rodents and mammals. In the present study, the effect of prenatal complex rhythmic music sound stimulation on postnatal spatial learning, memory and isolation stress was observed. Auditory stimulation with either music or species-specific sounds or no stimulation (control) was provided to separate sets of fertilized eggs from day 10 of incubation. Following hatching, the chicks at age 24, 72 and 120 h were tested on a T-maze for spatial learning and the memory of the learnt task was assessed 24 h after training. In the posthatch chicks at all ages, the plasma corticosterone levels were estimated following 10 min of isolation. The chicks of all ages in the three groups took less (p < 0.001) time to navigate the maze over the three trials thereby showing an improvement with training. In both sound-stimulated groups, the total time taken to reach the target decreased significantly (p < 0.01) in comparison to the unstimulated control group, indicating the facilitation of spatial learning. However, this decline was more at 24 h than at later posthatch ages. When tested for memory after 24 h of training, only the music-stimulated chicks at posthatch age 24 h took a significantly longer (p < 0.001) time to traverse the maze, suggesting a temporary impairment in their retention of the learnt task. In both sound-stimulated groups at 24 h, the plasma corticosterone levels were significantly decreased (p < 0.001) and increased thereafter at 72 h (p < 0.001) and 120 h which may contribute to the differential response in spatial learning. Thus, prenatal auditory stimulation with either species-specific or complex rhythmic music sounds facilitates spatial learning, though the music stimulation transiently impairs postnatal memory. PMID:21212638

  13. Reactions of Highly Uniform Zeolite H-Supported Rhodium Complexes: Transient Characterization by Infrared and X-ray Absorption Spectroscopies

    SciTech Connect

    Ogino, I.; Gates, B

    2010-01-01

    A zeolite H-{beta}-supported mononuclear rhodium diethene complex (Rh(C{sub 2}H{sub 4}){sub 2}{l_brace}O{sub 2}Al{r_brace}, where the braces indicate a part of the zeolite) was formed by the reaction of Rh(acac)({eta}{sub 2}-C{sub 2}H{sub 4}){sub 2} (acac = acetylacetonate, C{sub 5}H{sub 7}O{sub 2}{sup -}) with the zeolite. Transient characterization of the sample by X-ray absorption near edge structure (XANES) and infrared (IR) spectroscopies (combined with mass spectrometry of the effluent gas) while the sample was in contact with flowing CO indicates a simple stoichiometric conversion of the supported metal complex into another species, identified by the spectra as the zeolite-supported rhodium gem-dicarbonyl (Rh(CO){sub 2}{l_brace}O{sub 2}Al{r_brace}). The sharpness of the v{sub CO} bands in the IR spectrum indicates a high degree of uniformity of the supported rhodium gem-dicarbonyl, and isosbestic points in the XANES spectra as the transformation was occurring imply that the rhodium diethene complex was also highly uniform. Spectra similarly show that treatment of the supported rhodium gem-dicarbonyl with flowing C{sub 2}H{sub 4} resulted in another stoichiometrically simple transformation, giving a species suggested to be Rh(C{sub 2}H{sub 4})(CO){sub 2}{l_brace}O{sub 2}Al{r_brace}. The intermediate was ultimately transformed when the sample was purged with helium into another highly uniform supported species, inferred on the basis of IR spectra to be Rh(C{sub 2}H{sub 4})(CO){l_brace}O{sub 2}Al{r_brace}. Extended X-ray absorption fine structure spectra characterizing the supported rhodium diethene complex and the species formed from it show how the Rh-O bond distance at the Rh-support interface varied in response to the changes in the ligands bonded to the rhodium.

  14. The transient variation in the complexes of the low-latitude ionosphere within the equatorial ionization anomaly region of Nigeria

    NASA Astrophysics Data System (ADS)

    Rabiu, A. B.; Ogunsua, B. O.; Fuwape, I. A.; Laoye, J. A.

    2015-09-01

    The quest to find an index for proper characterization and description of the dynamical response of the ionosphere to external influences and its various internal irregularities has led to the study of the day-to-day variations of the chaoticity and dynamical complexity of the ionosphere. This study was conducted using Global Positioning System (GPS) total electron content (TEC) time series, measured in the year 2011, from five GPS receiver stations in Nigeria, which lies within the equatorial ionization anomaly region. The non-linear aspects of the TEC time series were obtained by detrending the data. The detrended TEC time series were subjected to various analyses to obtain the phase space reconstruction and to compute the chaotic quantifiers, which are Lyapunov exponents LE, correlation dimension, and Tsallis entropy, for the study of dynamical complexity. Considering all the days of the year, the daily/transient variations show no definite pattern for each month, but day-to-day values of Lyapunov exponents for the entire year show a wavelike semiannual variation pattern with lower values around March, April, September and October. This can be seen from the correlation dimension with values between 2.7 and 3.2, with lower values occurring mostly during storm periods, demonstrating a phase transition from higher dimension during the quiet periods to lower dimension during storms for most of the stations. The values of Tsallis entropy show a similar variation pattern to that of the Lyapunov exponent, with both quantifiers correlating within the range of 0.79 to 0.82. These results show that both quantifiers can be further used together as indices in the study of the variations of the dynamical complexity of the ionosphere. The presence of chaos and high variations in the dynamical complexity, even in quiet periods in the ionosphere, may be due to the internal dynamics and inherent irregularities of the ionosphere which exhibit non-linear properties. However, this

  15. Stochastic spontaneous calcium release events trigger premature ventricular complexes by overcoming electrotonic load

    PubMed Central

    Campos, Fernando O.; Shiferaw, Yohannes; Prassl, Anton J.; Boyle, Patrick M.; Vigmond, Edward J.; Plank, Gernot

    2015-01-01

    Aims Premature ventricular complexes (PVCs) due to spontaneous calcium (Ca) release (SCR) events at the cell level can precipitate ventricular arrhythmias. However, the mechanistic link between SCRs and PVC formation remains incompletely understood. The aim of this study was to investigate the conditions under which delayed afterdepolarizations resulting from stochastic subcellular SCR events can overcome electrotonic source–sink mismatch, leading to PVC initiation. Methods and results A stochastic subcellular-scale mathematical model of SCR was incorporated in a realistic model of the rabbit ventricles and Purkinje system (PS). Elevated levels of diastolic sarcoplasmic reticulum Ca2+ (CaSR) were imposed until triggered activity was observed, allowing us to compile statistics on probability, timing, and location of PVCs. At CaSR≥ 1500 µmol/L PVCs originated in the PS. When SCR was incapacitated in the PS, PVCs also emerged in the ventricles, but at a higher CaSR (≥1550 µmol/L) and with longer waiting times. For each model configuration tested, the probability of PVC occurrence increased from 0 to 100% within a well-defined critical CaSR range; this transition was much more abrupt in organ-scale models (∼50 µmol/L CaSR range) than in the tissue strand (∼100 µmol/L) or single-cell (∼450 µmol/L) models. Among PVCs originating in the PS, ∼68% were located near Purkinje-ventricular junctions (<1 mm). Conclusion SCR events overcome source–sink mismatch to trigger PVCs at a critical CaSR threshold. Above this threshold, PVCs emerge due to increased probability and reduced variability in timing of SCR events, leading to significant diastolic depolarization. Sites of lower electronic load, such as the PS, are preferential locations for triggering. PMID:25969391

  16. Event attribution using data assimilation in an intermediate complexity atmospheric model

    NASA Astrophysics Data System (ADS)

    Metref, Sammy; Hannart, Alexis; Ruiz, Juan; Carrassi, Alberto; Bocquet, Marc; Ghil, Michael

    2016-04-01

    A new approach, coined DADA (Data Assimilation for Detection and Attribution) has been recently introduced by Hannart et al. 2015, and is potentially useful for near real time, systematic causal attribution of weather and climate-related events The method is purposely designed to allow its operability at meteorological centers by synergizing causal attribution with Data Assimilation (DA) methods usually designed to deal with large nonlinear models. In Hannart et al. 2015, the DADA proposal is illustrated in the context of a low-order nonlinear model (forced three-variable Lorenz model) that is of course not realistic to represent the events considered. As a continuation of this stream of work, we therefore propose an implementation of the DADA approach in a realistic intermediate complexity atmospheric model (ICTP AGCM, nicknamed SPEEDY). The SPEEDY model is based on a spectral dynamical core developed at the Geophysical Fluid Dynamics Laboratory (see Held and Suarez 1994). It is a hydrostatic, r-coordinate, spectral-transform model in the vorticity-divergence form described by Bourke (1974). A synthetic dataset of observations of an extreme precipitation event over Southeastern South America is extracted from a long SPEEDY simulation under present climatic conditions (i.e. factual conditions). Then, following the DADA approach, observations of this event are assimilated twice in the SPEEDY model: first in the factual configuration of the model and second under its counterfactual, pre-industrial configuration. We show that attribution can be performed based on the likelihood ratio as in Hannart et al. 2015, but we further extend this result by showing that the likelihood can be split in space, time and variables in order to help identify the specific physical features of the event that bear the causal signature. References: Hannart A., A. Carrassi, M. Bocquet, M. Ghil, P. Naveau, M. Pulido, J. Ruiz, P. Tandeo (2015) DADA: Data assimilation for the detection and

  17. Heart Rate Deceleration as a Function of Viewing Complex Visual Events in Eighteen-Month-Old Infants.

    ERIC Educational Resources Information Center

    Gilmore, Lowry M.; And Others

    This research project assessed: (1) the practicality of recording heart rate in 18-month-old infants as they watched events filmed on color, silent motion picture films; and (2) the validity and sensitivity of heart rate change as an index of differential attention arousal elicited by changes within and between complex visual events. The research…

  18. Downscaling 20th century flooding events in complex terrain (Switzerland) using the WRF regional climate model

    NASA Astrophysics Data System (ADS)

    Heikkilä, Ulla; Gómez Navarro, Juan Jose; Franke, Jörg; Brönnimann, Stefan; Cattin, Réne

    2016-04-01

    Switzerland has experienced a number of severe precipitation events during the last few decades, such as during the 14-16 November of 2002 or during the 21-22 August of 2005. Both events, and subsequent extreme floods, caused fatalities and severe financial losses, and have been well studied both in terms of atmospheric conditions leading to extreme precipitation, and their consequences [e.g. Hohenegger et al., 2008, Stucki et al., 2012]. These examples highlight the need to better characterise the frequency and severity of flooding in the Alpine area. In a larger framework we will ultimately produce a high-resolution data set covering the entire 20th century to be used for detailed hydrological studies including all atmospheric parameters relevant for flooding events. In a first step, we downscale the aforementioned two events of 2002 and 2005 to assess the model performance regarding precipitation extremes. The complexity of the topography in the Alpine area demands high resolution datasets. To achieve a sufficient detail in resolution we employ the Weather Research and Forecasting regional climate model (WRF). A set of 4 nested domains is used with a 2-km resolution horizontal resolution over Switzerland. The NCAR 20th century reanalysis (20CR) with a horizontal resolution of 2.5° serves as boundary condition [Compo et al., 2011]. First results of the downscaling the 2002 and 2005 extreme precipitation events show that, compared to station observations provided by the Swiss Meteorological Office MeteoSwiss, the model strongly underestimates the strength of these events. This is mainly due to the coarse resolution of the 20CR data, which underestimates the moisture fluxes during these events. We tested driving WRF with the higher-resolved NCEP reanalysis and found a significant improvement in the amount of precipitation of the 2005 event. In a next step we will downscale the precipitation and wind fields during a 6-year period 2002-2007 to investigate and

  19. Very high energy gamma-ray observation of the peculiar transient event Swift J1644+57 with the MAGIC telescopes and AGILE

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Backes, M.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnefoy, S.; Bonnoli, G.; Borla Tridon, D.; Bretz, T.; Carmona, E.; Carosi, A.; Carreto Fidalgo, D.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; Delgado Mendez, C.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadamek, A.; Hadasch, D.; Herrero, A.; Hose, J.; Hrupec, D.; Idec, W.; Jankowski, F.; Kadenius, V.; Klepser, S.; Knoetig, M. L.; Krähenbühl, T.; Krause, J.; Kushida, J.; La Barbera, A.; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Masbou, J.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nowak, N.; Orito, R.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Partini, S.; Persic, M.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zandanel, F.; Zanin, R.; Longo, F.; Lucarelli, F.; Pittori, C.; Verrecchia, F.

    2013-04-01

    Context. On March 28, 2011, the BAT instrument on board the Swift satellite detected a new transient event that in the very beginning was classified as a gamma ray burst (GRB). However, the unusual X-ray flaring activity observed from a few hours up to days after the onset of the event made a different nature seem to be more likely. The long-lasting activity in the X-ray band, followed by a delayed brightening of the source in infrared and radio activity, suggested that it is better interpreted as a tidal disruption event that triggered a dormant black hole in the nucleus of the host galaxy and generated an outflowing jet of relativistic matter. Aims: Detecting a very high energy emission component from such a peculiar object would be enable us to constrain the dynamic of the emission processes and the jet model by providing information on the Doppler factor of the relativistic ejecta . Methods: The MAGIC telescopes observed the peculiar source Swift J1644+57 during the flaring phase, searching for gamma-ray emission at very-high energy (VHE, E > 100 GeV), starting observations nearly 2.5 days after the trigger time. MAGIC collected a total of 28 h of data during 12 nights. The source was observed in wobble mode during dark time at a mean zenith angle of 35°. Data were reduced using a new image-cleaning algorithm, the so-called sum-cleaning, which guarantees a better noise suppression and a lower energy threshold than the standard analysis procedure. Results: No clear evidence for emission above the energy threshold of 100 GeV was found. MAGIC observations permit one to constrain the emission from the source down to 100 GeV, which favors models that explain the observed lower energy variable emission. Data analysis of simultaneous observations from AGILE, Fermi and VERITAS also provide negative detection, which additionally constrain the self-Compton emission component.

  20. Complex networks identify spatial patterns of extreme rainfall events of the South American Monsoon System

    NASA Astrophysics Data System (ADS)

    Boers, Niklas; Bookhagen, Bodo; Marwan, Norbert; Kurths, Jürgen; Marengo, José

    2013-08-01

    We investigate the spatial characteristics of extreme rainfall synchronicity of the South American Monsoon System (SAMS) by means of Complex Networks (CN). By introducing a new combination of CN measures and interpreting it in a climatic context, we investigate climatic linkages and classify the spatial characteristics of extreme rainfall synchronicity. Although our approach is based on only one variable (rainfall), it reveals the most important features of the SAMS, such as the main moisture pathways, areas with frequent development of Mesoscale Convective Systems (MCS), and the major convergence zones. In addition, our results reveal substantial differences between the spatial structures of rainfall synchronicity above the 90th and above the 95th percentiles. Most notably, events above the 95th percentile contribute stronger to MCS in the La Plata Basin.

  1. Words Analysis of Online Chinese News Headlines about Trending Events: A Complex Network Perspective

    PubMed Central

    Li, Huajiao; Fang, Wei; An, Haizhong; Huang, Xuan

    2015-01-01

    Because the volume of information available online is growing at breakneck speed, keeping up with meaning and information communicated by the media and netizens is a new challenge both for scholars and for companies who must address public relations crises. Most current theories and tools are directed at identifying one website or one piece of online news and do not attempt to develop a rapid understanding of all websites and all news covering one topic. This paper represents an effort to integrate statistics, word segmentation, complex networks and visualization to analyze headlines’ keywords and words relationships in online Chinese news using two samples: the 2011 Bohai Bay oil spill and the 2010 Gulf of Mexico oil spill. We gathered all the news headlines concerning the two trending events in the search results from Baidu, the most popular Chinese search engine. We used Simple Chinese Word Segmentation to segment all the headlines into words and then took words as nodes and considered adjacent relations as edges to construct word networks both using the whole sample and at the monthly level. Finally, we develop an integrated mechanism to analyze the features of words’ networks based on news headlines that can account for all the keywords in the news about a particular event and therefore track the evolution of news deeply and rapidly. PMID:25807376

  2. Words analysis of online Chinese news headlines about trending events: a complex network perspective.

    PubMed

    Li, Huajiao; Fang, Wei; An, Haizhong; Huang, Xuan

    2015-01-01

    Because the volume of information available online is growing at breakneck speed, keeping up with meaning and information communicated by the media and netizens is a new challenge both for scholars and for companies who must address public relations crises. Most current theories and tools are directed at identifying one website or one piece of online news and do not attempt to develop a rapid understanding of all websites and all news covering one topic. This paper represents an effort to integrate statistics, word segmentation, complex networks and visualization to analyze headlines' keywords and words relationships in online Chinese news using two samples: the 2011 Bohai Bay oil spill and the 2010 Gulf of Mexico oil spill. We gathered all the news headlines concerning the two trending events in the search results from Baidu, the most popular Chinese search engine. We used Simple Chinese Word Segmentation to segment all the headlines into words and then took words as nodes and considered adjacent relations as edges to construct word networks both using the whole sample and at the monthly level. Finally, we develop an integrated mechanism to analyze the features of words' networks based on news headlines that can account for all the keywords in the news about a particular event and therefore track the evolution of news deeply and rapidly. PMID:25807376

  3. Sentiment Diffusion of Public Opinions about Hot Events: Based on Complex Network.

    PubMed

    Hao, Xiaoqing; An, Haizhong; Zhang, Lijia; Li, Huajiao; Wei, Guannan

    2015-01-01

    To study the sentiment diffusion of online public opinions about hot events, we collected people's posts through web data mining techniques. We calculated the sentiment value of each post based on a sentiment dictionary. Next, we divided those posts into five different orientations of sentiments: strongly positive (P), weakly positive (p), neutral (o), weakly negative (n), and strongly negative (N). These sentiments are combined into modes through coarse graining. We constructed sentiment mode complex network of online public opinions (SMCOP) with modes as nodes and the conversion relation in chronological order between different types of modes as edges. We calculated the strength, k-plex clique, clustering coefficient and betweenness centrality of the SMCOP. The results show that the strength distribution obeys power law. Most posts' sentiments are weakly positive and neutral, whereas few are strongly negative. There are weakly positive subgroups and neutral subgroups with ppppp and ooooo as the core mode, respectively. Few modes have larger betweenness centrality values and most modes convert to each other with these higher betweenness centrality modes as mediums. Therefore, the relevant person or institutes can take measures to lead people's sentiments regarding online hot events according to the sentiment diffusion mechanism. PMID:26462230

  4. A Validation System for the Complex Event Processing Directives of the ATLAS Shifter Assistant Tool

    NASA Astrophysics Data System (ADS)

    Santos, A.; Anders, G.; Avolio, G.; Kazarov, A.; Lehmann Miotto, G.; Soloviev, I.

    2015-12-01

    Complex Event Processing (CEP) is a methodology that combines data from many sources in order to identify events or patterns that need particular attention. It has gained a lot of momentum in the computing world in the past few years and is used in ATLAS to continuously monitor the behaviour of the data acquisition system, to trigger corrective actions and to guide the experiment's operators. This technology is very powerful, if experts regularly insert and update their knowledge about the system's behaviour into the CEP engine. Nevertheless, writing or modifying CEP rules is not trivial since the used programming paradigm is quite different with respect to what developers are normally familiar with. In order to help experts verify that the rules work as expected, we have thus developed a complete testing and validation environment. This system consists of three main parts: the first is the data reader from existing storage of all relevant data streams that are produced during data taking, the second is a playback tool that allows to re-inject data of specific data taking sessions from the past into the CEP engine, and the third is a reporting tool that shows the output that the rules loaded into the engine would have produced in the live system. In this paper we describe the design and implementation of this validation system, highlight its strengths and shortcomings and indicate how such a system could be reused in similar projects.

  5. Sentiment Diffusion of Public Opinions about Hot Events: Based on Complex Network

    PubMed Central

    Hao, Xiaoqing; An, Haizhong; Zhang, Lijia; Li, Huajiao; Wei, Guannan

    2015-01-01

    To study the sentiment diffusion of online public opinions about hot events, we collected people’s posts through web data mining techniques. We calculated the sentiment value of each post based on a sentiment dictionary. Next, we divided those posts into five different orientations of sentiments: strongly positive (P), weakly positive (p), neutral (o), weakly negative (n), and strongly negative (N). These sentiments are combined into modes through coarse graining. We constructed sentiment mode complex network of online public opinions (SMCOP) with modes as nodes and the conversion relation in chronological order between different types of modes as edges. We calculated the strength, k-plex clique, clustering coefficient and betweenness centrality of the SMCOP. The results show that the strength distribution obeys power law. Most posts’ sentiments are weakly positive and neutral, whereas few are strongly negative. There are weakly positive subgroups and neutral subgroups with ppppp and ooooo as the core mode, respectively. Few modes have larger betweenness centrality values and most modes convert to each other with these higher betweenness centrality modes as mediums. Therefore, the relevant person or institutes can take measures to lead people’s sentiments regarding online hot events according to the sentiment diffusion mechanism. PMID:26462230

  6. Hydrogen-Bound Complexes of Tropolone: Gateways for the Interrogation of Multiple Proton-Transfer Events

    NASA Astrophysics Data System (ADS)

    Nemchick, Deacon J.; Chew, Kathryn; Wolff, John E.; Vaccaro, Patrick H.

    2011-06-01

    Tropolone (TrOH) serves as a model system for the study of coherent proton-transfer processes, where a potential barrier of finite height hinders the symmetric exchange of a lone hydron between hydroxylic (proton-donating) and ketonic (proton-accepting) oxygen centers. This talk will discuss ongoing efforts to build upon the known structural and dynamical properties of tropolone so as to explore related multiple proton-transfer events that are mediated by successive formation and breaking of several hydrogen bonds. Of particular interest are weakly-bound complexes created in situ under ``cold'' molecular-beam conditions by docking amphoteric ligands (e.g., HF and HCOOH) into the reaction cleft of the TrOH substrate. Such species have the tantalizing possibility of undergoing double proton transfer, with resulting tunneling-induced bifurcation of rovibronic features reflecting the intrinsic vibrational and/or electronic specificity of the attendant unimolecular transformation. Spectroscopic studies of several hydrogen-bound TrOH complexes through use of the richly structured tilde{A}1B2-tilde{X}1A1 (π *← π ) absorption system will be presented, with complementary quantum-chemical calculations serving to guide the assignment and interpretation of observed spectral patterns. L. A. Burns, D. Murdock, and P. H. Vaccaro, Mol. Phys., 108, 1171 (2010).

  7. Effect of supply voltage and body-biasing on single-event transient pulse quenching in bulk fin field-effect-transistor process

    NASA Astrophysics Data System (ADS)

    Jun-Ting, Yu; Shu-Ming, Chen; Jian-Jun, Chen; Peng-Cheng, Huang; Rui-Qiang, Song

    2016-04-01

    Charge sharing is becoming an important topic as the feature size scales down in fin field-effect-transistor (FinFET) technology. However, the studies of charge sharing induced single-event transient (SET) pulse quenching with bulk FinFET are reported seldomly. Using three-dimensional technology computer aided design (3DTCAD) mixed-mode simulations, the effects of supply voltage and body-biasing on SET pulse quenching are investigated for the first time in bulk FinFET process. Research results indicate that due to an enhanced charge sharing effect, the propagating SET pulse width decreases with reducing supply voltage. Moreover, compared with reverse body-biasing (RBB), the circuit with forward body-biasing (FBB) is vulnerable to charge sharing and can effectively mitigate the propagating SET pulse width up to 53% at least. This can provide guidance for radiation-hardened bulk FinFET technology especially in low power and high performance applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61376109, 61434007, and 61176030).

  8. Design and performances of microcameras and photometers instruments on TARANIS satellite for an advanced characterization of Transient Luminous Event in the upper atmosphere

    NASA Astrophysics Data System (ADS)

    Le Mer-Dachard, Fanny; Cansot, Elodie; Hébert, Philippe; Farges, Thomas; Ravel, Karen; Gaillac, Stéphanie

    2015-10-01

    The TARANIS mission aims at studying upper atmosphere coupling with a scientific nadir-pointing microsatellite - CNES Myriade family - at a low-altitude orbit (700 km). The main objectives are to measure the occurrence of Transient Luminous Event (TLE), impulsive energetic optical phenomena generated by storms according to recently discovered process, and Terrestrial Gamma-ray Flash (TGF), their emissions and trigger factors. TARANIS instruments are currently in manufacturing, assembly, integration and testing phase. The MicroCameras and Photometers instruments (MCP) are in charge of the remote sensing of the sprites and the lightning in optical wavelengths. MicroCameras instrument [MCP-MC] is an imager in the visible and Photometers instrument [MCP-PH] is a radiometer with four bands from UV to NIR, able to detect TLEs on-board and to trigger the whole payload. The satellite will provide a complete survey of the atmosphere in low resolution together with a high resolution data of sites of interest automatically detected on board. For MC and PH instruments, CEA defined scientific needs and is in charge of processing data and providing scientific results. CNES described the technical requirements of these two instruments and will run in-flight commissioning. Design, manufacturing and testing is under responsibility of Sodern for MicroCameras and Bertin Technologies for Photometers. This article shortly describes physical characteristics of TLEs and presents the final design of these instruments and first measured performances.

  9. Collaborative-Comparison Learning for Complex Event Detection Using Distributed Hierarchical Graph Neuron (DHGN) Approach in Wireless Sensor Network

    NASA Astrophysics Data System (ADS)

    Muhamad Amin, Anang Hudaya; Khan, Asad I.

    Research trends in existing event detection schemes using Wireless Sensor Network (WSN) have mainly focused on routing and localisation of nodes for optimum coordination when retrieving sensory information. Efforts have also been put in place to create schemes that are able to provide learning mechanisms for event detection using classification or clustering approaches. These schemes entail substantial communication and computational overheads owing to the event-oblivious nature of data transmissions. In this paper, we present an event detection scheme that has the ability to distribute detection processes over the resource-constrained wireless sensor nodes and is suitable for events with spatio-temporal characteristics. We adopt a pattern recognition algorithm known as Distributed Hierarchical Graph Neuron (DHGN) with collaborative-comparison learning for detecting critical events in WSN. The scheme demonstrates good accuracy for binary classification and offers low-complexity and high-scalability in terms of its processing requirements.

  10. Radiochemical data collected on events from which radioactivity escaped beyond the borders of the Nevada test range complex. [NONE

    SciTech Connect

    Hicks, H.G.

    1981-02-12

    This report identifies all nuclear events in Nevada that are known to have sent radioactivity beyond the borders of the test range complex. There have been 177 such tests, representing seven different types: nuclear detonations in the atmosphere, nuclear excavation events, nuclear safety events, underground nuclear events that inadvertently seeped or vented to the atmosphere, dispersion of plutonium and/or uranium by chemical high explosives, nuclear rocket engine tests, and nuclear ramjet engine tests. The source term for each of these events is given, together with the data base from which it was derived (except where the data are classified). The computer programs used for organizing and processing the data base and calculating radionuclide production are described and included, together with the input and output data and details of the calculations. This is the basic formation needed to make computer modeling studies of the fallout from any of these 177 events.

  11. Complex Negative Regulation of TLR9 by Multiple Proteolytic Cleavage Events.

    PubMed

    Sinha, Siddhartha S; Cameron, Jody; Brooks, James C; Leifer, Cynthia A

    2016-08-15

    TLR9 is an innate immune receptor important for recognizing DNA of host and foreign origin. A mechanism proposed to prevent excessive response to host DNA is the requirement for proteolytic cleavage of TLR9 in endosomes to generate a mature form of the receptor (TLR9(471-1032)). We previously described another cleavage event in the juxtamembrane region of the ectodomain that generated a dominant-negative form of TLR9. Thus, there are at least two independent cleavage events that regulate TLR9. In this study, we investigated whether an N-terminal fragment of TLR9 could be responsible for regulation of the mature or negative-regulatory form. We show that TLR9(471-1032), corresponding to the proteolytically cleaved form, does not function on its own. Furthermore, activity is not rescued by coexpression of the N-terminal fragment (TLR9(1-440)), inclusion of the hinge region (TLR9(441-1032)), or overexpression of UNC93B1, the last of which is critical for trafficking and cleavage of TLR9. TLR9(1-440) coimmunoprecipitates with full-length TLR9 and TLR9(471-1032) but does not rescue the native glycosylation pattern; thus, inappropriate trafficking likely explains why TLR9(471-1032) is nonfunctional. Lastly, we show that TLR9(471-1032) is also a dominant-negative regulator of TLR9 signaling. Together, these data provide a new perspective on the complexity of TLR9 regulation by proteolytic cleavage and offer potential ways to inhibit activity through this receptor, which may dampen autoimmune inflammation. PMID:27421483

  12. Strategy for introduction of rainwater management facility considering rainfall event applied on new apartment complex

    NASA Astrophysics Data System (ADS)

    KIM, H.; Lee, D. K.; Yoo, S.

    2014-12-01

    As regional torrential rains become frequent due to climate change, urban flooding happens very often. That is why it is necessary to prepare for integrated measures against a wide range of rainfall. This study proposes introduction of effective rainwater management facilities to maximize the rainwater runoff reductions and recover natural water circulation for unpredictable extreme rainfall in apartment complex scale. The study site is new apartment complex in Hanam located in east of Seoul, Korea. It has an area of 7.28ha and is analysed using the EPA-SWMM and STORM model. First, it is analyzed that green infrastructure(GI) had efficiency of flood reduction at the various rainfall events and soil characteristics, and then the most effective value of variables are derived. In case of rainfall event, Last 10 years data of 15 minutes were used for analysis. A comparison between A(686mm rainfall during 22days) and B(661mm/4days) knew that soil infiltration of A is 17.08% and B is 5.48% of the rainfall. Reduction of runoff after introduction of the GI of A is 24.76% and B is 6.56%. These results mean that GI is effective to small rainfall intensity, and artificial rainwater retarding reservoir is needed at extreme rainfall. Second, set of target year is conducted for the recovery of hydrological cycle at the predevelopment. And an amount of infiltration, evaporation, surface runoff of the target year and now is analysed on the basis of land coverage, and an arrangement of LID facilities. Third, rainwater management scenarios are established and simulated by the SWMM-LID. Rainwater management facilities include GI(green roof, porous pavement, vegetative swale, ecological pond, and raingarden), and artificial rainwater. Design scenarios are categorized five type: 1)no GI, 2)conventional GI design(current design), 3)intensive GI design, 4)GI design+rainwater retarding reservoir 5)maximized rainwater retarding reservoir. Intensive GI design is to have attribute value to

  13. Error Analysis of Satellite Precipitation-Driven Modeling of Complex Terrain Flood Events

    NASA Astrophysics Data System (ADS)

    Mei, Y.; Nikolopoulos, E. I.; Anagnostou, E. N.; Zoccatelli, D.; Borga, M., Sr.

    2015-12-01

    The error characteristics of satellite precipitation driven flood event simulations over mountainous basins are evaluated in this study for eight different global satellite products. A methodology is devised to match the observed records of the flood events with the corresponding satellite and reference rainfall and runoff simulations. The flood events are sorted according to flood type (i.e. rain flood and flash flood) and basin's antecedent conditions represented by the event's runoff-to-precipitation ratio. The satellite precipitation products and runoff simulations are evaluated based on systematic and random error metrics applied on the matched event pairs and basin scale event properties (i.e. cumulative volume, timing and shape). Overall satellite-driven event runoff exhibits better error metrics than the satellite precipitation. Better error metrics are also shown for the rain flood events relative to the flash flood events. The event timing and shape from satellite-derived precipitation agreed well with the reference; the cumulative volume is mostly underestimated. In terms of error propagation, the study shows dampening effect in both systematic and random error components of the satellite-driven runoff time series relative to the satellite-retrieved event precipitation. This error dampening effect is less pronounced for the flash flood events and the rain flood events with high runoff coefficients. This study provides for a first time flood event characteristics of the satellite precipitation error propagation in flood modeling, which has implications on the Global Precipitation Measurement application in mountain flood hydrology.

  14. Quartz veins deformed by diffusion creep-accommodated grain boundary sliding during a transient, high strain-rate event in the Southern Alps, New Zealand

    NASA Astrophysics Data System (ADS)

    Wightman, Ruth H.; Prior, David J.; Little, Timothy A.

    2006-05-01

    The crystallographic preferred orientations (CPOs) and microstructures of deformed quartz veins were measured for four samples in the hanging-wall of the Alpine Fault in the Southern Alps, New Zealand. Their deformation and exhumation has occurred since 4 Ma. The quartz veins have been ductilely sheared to finite shear-strains of 5-15 in late Cenozoic shear zones at 450±50 °C, 310±90 MPa and strain-rates between 2×10 -11 and 2×10 -9 s -1. The sheared veins have a polygonal microstructure with few subgrains and an average grain-size of ˜100 μm. The CPO of the veins is random to very weak within the shear zones. We suggest that dislocation creep accommodated initial shear deformation, at high stresses and strain-rates. The deformation must have created a strong CPO and concomitant dynamic recrystallization reduced the grain-size significantly. Dissipation of stresses during initial deformation lead to a stress and strain-rate drop required for a switch to diffusion creep-accommodated grain boundary sliding (GBS). Continued shearing accommodated by GBS destroyed the CPO. Post-deformational grain growth gave rise to a final polygonal microstructure with a similar grain size in veins and in the wall rocks. Analysis of existing experimental data suggest that this sequence of events is possible in the time available. Rates of all processes may have been enhanced by the presence of a water-rich fluid within the shear zones. These observations of naturally deformed rocks provide a model for the processes that may occur during short-lived deformation at transiently-high stresses at mid-crustal depths or deeper.

  15. Complex Parts, Complex Data: Why You Need to Understand What Radiation Single Event Testing Data Does and Doesn't Show and the Implications Thereof

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Berg, Melanie D.

    2015-01-01

    Electronic parts (integrated circuits) have grown in complexity such that determining all failure modes and risks from single particle event testing is impossible. In this presentation, the authors will present why this is so and provide some realism on what this means. Its all about understanding actual risks and not making assumptions.

  16. Complex Parts, Complex Data: Why You Need to Understand What Radiation Single Event Testing Data Does and Doesn't Show and the Implications Thereof

    NASA Technical Reports Server (NTRS)

    Label, Kenneth A.; Berg, Melanie D.

    2016-01-01

    Electronic parts (integrated circuits) have grown in complexity such that determining all failure modes and risks from single particle event testing is impossible. In this presentation, the authors will present why this is so and provide some realism on what this means. Its all about understanding actual risks and not making assumptions.

  17. World, We Have Problems: Simulation for Large Complex, Risky Projects, and Events

    NASA Technical Reports Server (NTRS)

    Elfrey, Priscilla

    2010-01-01

    Prior to a spacewalk during the NASA STS/129 mission in November 2009, Columbia Broadcasting System (CBS) correspondent William Harwood reported astronauts, "were awakened again", as they had been the day previously. Fearing something not properly connected was causing a leak, the crew, both on the ground and in space, stopped and checked everything. The alarm proved false. The crew did complete its work ahead of schedule, but the incident reminds us that correctly connecting hundreds and thousands of entities, subsystems and systems, finding leaks, loosening stuck valves, and adding replacements to very large complex systems over time does not occur magically. Everywhere major projects present similar pressures. Lives are at - risk. Responsibility is heavy. Large natural and human-created disasters introduce parallel difficulties as people work across boundaries their countries, disciplines, languages, and cultures with known immediate dangers as well as the unexpected. NASA has long accepted that when humans have to go where humans cannot go that simulation is the sole solution. The Agency uses simulation to achieve consensus, reduce ambiguity and uncertainty, understand problems, make decisions, support design, do planning and troubleshooting, as well as for operations, training, testing, and evaluation. Simulation is at the heart of all such complex systems, products, projects, programs, and events. Difficult, hazardous short and, especially, long-term activities have a persistent need for simulation from the first insight into a possibly workable idea or answer until the final report perhaps beyond our lifetime is put in the archive. With simulation we create a common mental model, try-out breakdowns of machinery or teamwork, and find opportunity for improvement. Lifecycle simulation proves to be increasingly important as risks and consequences intensify. Across the world, disasters are increasing. We anticipate more of them, as the results of global warming

  18. Modelling of a Zonda wind event in a complex terrain region using WRF

    NASA Astrophysics Data System (ADS)

    Fernandez, R. P.; Cremades, P. G.; Lakkis, G.; Allende, D. G.; Santos, R.; Puliafito, S. E.

    2012-04-01

    The air quality modeling in a regional scale requires the coupling to Numerical Weather Prediction (NWP) models, mainly when a high spatial and temporal resolution is required, such as in those cases related to large pollutants emissions episodes or extreme weather events. The Weather Research and Forecasting (WRF) is a last generation NWP model which computes temperature, pressure, humidity and wind fields in high spatial and temporal resolution. In order to perform simulations in complex terrain regions, WRF must be locally configured to obtain a proper representation of the physical processes, and an independent validation must be performed, both under common and extreme conditions. Once the local configuration is obtained, a full atmospheric chemistry modeling can be performed by means of WRF-Chem. In this work a mesoescale event of Zonda wind (similar to Foehn and Chinook winds) affecting the topographically complex mountainous region of Mendoza (Argentina) on February 15th, 2007 is represented using WRF. The model results are compared to the Argentine National Weather Service (SMN) observations at "El Plumerillo" station (WMO #87418), showing a good performance. A description of the local model configuration and most important physical parameterizations selected for the simulations is given, including the improvement of the default resolution of land use and land cover (LULC) fields. The high resolution modeling domain considered is centered at the city of Mendoza (32° 53' South, 68° 50' West), it extends 200 km N/S × 160 km E/W and includes a 3-nested domain downscaling of 36, 12 and 4 km resolution, respectively. The results for the Zonda wind episode show a very good performance of the model both in spatial and temporal scales. The temporal dew point variation (the physical variable that best describes the Zonda wind) shows a good agreement with the measured values, with a sharp decrease of 20 °C (from 16 °C to -4 °C) in 3 hours. A full 3-D regional

  19. Modulation of flash-induced photosystem II fluorescence by events occurring at the water oxidizing complex.

    PubMed

    Putrenko, I I; Vasil'ev, S; Bruce, D

    1999-08-17

    The mechanism of flash-induced changes with a periodicity of four in photosystem II (PSII) fluorescence was investigated with the aim of further using fluorescence measurements as an approach to studying the structural and functional organization of the water-oxidizing complex (WOC). The decay of the flash-induced high fluorescence state of PSII was measured with pulse amplitude modulated fluorometry in thylakoids and PSII enriched membrane fragments. Calculated QA- decay was well described by three exponential decay components, reflecting QA- reoxidation with halftimes of 450 and 860 micros, 2 and 7.6 ms, and 111 and 135 ms in thylakoids and PSII membranes, respectively. The effect of modification of the PSII donor side by changing pH or by removal of the extrinsic 17 and 24 kDa proteins on period four oscillations in both maximum fluorescence yield and the relative contribution of QA- reoxidation reactions was compared to flash-induced oxygen yield. The four-step oxidation of the manganese cluster of the WOC was found to be necessary but not sufficient to produce modulation of PSII fluorescence. The capacity of the WOC to generate molecular oxygen was also required to observe a period four in the fluorescence; however, direct quenching by oxygen was not responsible for the modulation. Potential mechanisms responsible for the periodicity of four in both maximum fluorescence yield pattern and flash-dependent changes in proportion of centers with different QA- reoxidation rates are discussed with respect to intrinsic deprotonation events occurring at the WOC. PMID:10451357

  20. Offside Decisions by Expert Assistant Referees in Association Football: Perception and Recall of Spatial Positions in Complex Dynamic Events

    ERIC Educational Resources Information Center

    Gilis, Bart; Helsen, Werner; Catteeuw, Peter; Wagemans, Johan

    2008-01-01

    This study investigated the offside decision-making process in association football. The first aim was to capture the specific offside decision-making skills in complex dynamic events. Second, we analyzed the type of errors to investigate the factors leading to incorrect decisions. Federation Internationale de Football Association (FIFA; n = 29)…

  1. Monte Carlo model for analysis of thermal runaway electrons in streamer tips in transient luminous events and streamer zones of lightning leaders

    NASA Astrophysics Data System (ADS)

    Moss, Gregory D.; Pasko, Victor P.; Liu, Ningyu; Veronis, Georgios

    2006-02-01

    Streamers are thin filamentary plasmas that can initiate spark discharges in relatively short (several centimeters) gaps at near ground pressures and are also known to act as the building blocks of streamer zones of lightning leaders. These streamers at ground pressure, after 1/N scaling with atmospheric air density N, appear to be fully analogous to those documented using telescopic imagers in transient luminous events (TLEs) termed sprites, which occur in the altitude range 40-90 km in the Earth's atmosphere above thunderstorms. It is also believed that the filamentary plasma structures observed in some other types of TLEs, which emanate from the tops of thunderclouds and are termed blue jets and gigantic jets, are directly linked to the processes in streamer zones of lightning leaders. Acceleration, expansion, and branching of streamers are commonly observed for a wide range of applied electric fields. Recent analysis of photoionization effects on the propagation of streamers indicates that very high electric field magnitudes ˜10 Ek, where Ek is the conventional breakdown threshold field defined by the equality of the ionization and dissociative attachment coefficients in air, are generated around the tips of streamers at the stage immediately preceding their branching. This paper describes the formulation of a Monte Carlo model, which is capable of describing electron dynamics in air, including the thermal runaway phenomena, under the influence of an external electric field of an arbitrary strength. Monte Carlo modeling results indicate that the ˜10 Ek fields are able to accelerate a fraction of low-energy (several eV) streamer tip electrons to energies of ˜2-8 keV. With total potential differences on the order of tens of MV available in streamer zones of lightning leaders, it is proposed that during a highly transient negative corona flash stage of the development of negative stepped leader, electrons with energies 2-8 keV ejected from streamer tips near

  2. Deciphering landscape complexity to predict (non)linear responses to extreme climatic events

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extreme events are increasing in frequency and magnitude for many landscapes globally. Ecologically, most of the focus on extreme climatic events has been on effects of either short-term pulses (floods, freezes) or long-term drought. Multi-year increases in precipitation are also occurring with litt...

  3. An event generator for simulations of complex β-decay experiments

    NASA Astrophysics Data System (ADS)

    Jordan, D.; Algora, A.; Tain, J. L.

    2016-08-01

    This article describes a Monte Carlo event generator for the design, optimization and performance characterization of beta decay spectroscopy experimental set-ups. The event generator has been developed within the Geant4 simulation architecture and provides new features and greater flexibility in comparison with the current available decay generator.

  4. Effects of serum immunoglobulins from patients with complex regional pain syndrome (CRPS) on depolarisation-induced calcium transients in isolated dorsal root ganglion (DRG) neurons.

    PubMed

    Reilly, Joanne M; Dharmalingam, Backialakshmi; Marsh, Stephen J; Thompson, Victoria; Goebel, Andreas; Brown, David A

    2016-03-01

    Complex regional pain syndrome (CRPS) is thought to have an auto-immune component. One such target recently proposed from the effects of auto-immune IgGs on Ca(2+) transients in cardiac myocytes and cell lines is the α1-adrenoceptor. We have tested whether such IgGs exerted comparable effects on nociceptive sensory neurons isolated from rat dorsal root ganglia. Depolarisation-induced [Ca(2+)]i transients were generated by applying 30 mM KCl for 2 min and monitored by Fura-2 fluorescence imaging. No IgGs tested (including 3 from CRPS patients) had any significant effect on these [Ca(2+)]i transients. However, IgG from one CRPS patient consistently and significantly reduced the K(+)-induced response of cells that had been pre-incubated for 24h with a mixture of inflammatory mediators (1 μM histamine, 5-hydroxytryptamine, bradykinin and PGE2). Since this pre-incubation also appeared to induce a comparable inhibitory response to the α1-agonist phenylephrine, this is compatible with the α1-adrenoceptor as a target for CRPS auto-immunity. A mechanism whereby this might enhance pain is suggested. PMID:26708558

  5. Transient DNA / RNA-protein interactions.

    PubMed

    Blanco, Francisco J; Montoya, Guillermo

    2011-05-01

    The great pace of biomolecular structure determination has provided a plethora of protein structures, but not as many structures of nucleic acids or of their complexes with proteins. The recognition of DNA and RNA molecules by proteins may produce large and relatively stable assemblies (such as the ribosome) or transient complexes (such as DNA clamps sliding through the DNA). These transient interactions are most difficult to characterize, but even in 'stable' complexes captured in crystal structures, the dynamics of the whole or part of the assembly pose great technical difficulties in understanding their function. The development and refinement of powerful experimental and computational tools have made it possible to learn a great deal about the relevance of these fleeting events for numerous biological processes. We discuss here the most recent findings and the challenges that lie ahead in the quest for a better understanding of protein-nucleic acid interactions. PMID:21410646

  6. Development of a microwave transmission setup for time-resolved measurements of the transient complex conductivity in bulk samples

    NASA Astrophysics Data System (ADS)

    Schins, J. M.; Prins, P.; Grozema, F. C.; Abellón, R. D.; de Haas, M. P.; Siebbeles, L. D. A.

    2005-08-01

    We describe and characterize a microwave transmission setup for the measurement of radiation-induced transient conductivities in the frequency range between 26 and 38GHz (Q band). This technique combines the virtues of two already existing techniques. On one hand, the microwave transmission technique is well established for the determination of (quasi)static conductivities, but requires adaptations to be suitable to the determination of transient conductivities with 1ns temporal resolution. On the other hand, the transient conductivity technique is well established, too, but in its present form (using a reflection configuration) it suffers from a poor signal to noise ratio due to unwanted interferences. These interferences are due to the circulator, which diverts part of the incoming microwave flux directly to the detector. We characterized the transmission setup by measuring the real and imaginary components of the conductivity of pulse irradiated CO2 gas at different pressures, and compared these results to predictions of the Drude model. CO2 was chosen as a test sample because of its well characterized behavior when irradiated with MeV electron pulses, and the fact that a wide range of the ratios of imaginary to real components of the conductivity are obtainable by just controlling the pressure. For intrinsic bulk isolators (either powders or in solution) pulse-induced conductivity changes as small as 10-8S /m can be measured with nanosecond time resolution. The ratio of the imaginary to real part of the conductivity can be measured in the range from 0.084 to 28, which means that the dynamic range has been increased more than 100-fold with respect to the customary reflection setup.

  7. Chemotaxis Control of Transient Cell Aggregation

    PubMed Central

    2015-01-01

    Chemotaxis affords motile cells the ability to rapidly respond to environmental challenges by navigating cells to niches favoring growth. Such a property results from the activities of dedicated signal transduction systems on the motility apparatus, such as flagella, type IV pili, and gliding machineries. Once cells have reached a niche with favorable conditions, they often stop moving and aggregate into complex communities termed biofilms. An intermediate and reversible stage that precedes commitment to permanent adhesion often includes transient cell-cell contacts between motile cells. Chemotaxis signaling has been implicated in modulating the transient aggregation of motile cells. Evidence further indicates that chemotaxis-dependent transient cell aggregation events are behavioral responses to changes in metabolic cues that temporarily prohibit permanent attachment by maintaining motility and chemotaxis. This minireview discusses a few examples illustrating the role of chemotaxis signaling in the initiation of cell-cell contacts in bacteria moving via flagella, pili, or gliding. PMID:26216846

  8. Usefulness of Fragmented QRS Complex to Predict Arrhythmic Events and Cardiovascular Mortality in Patients With Noncompaction Cardiomyopathy.

    PubMed

    Cetin, Mehmet Serkan; Ozcan Cetin, Elif Hande; Canpolat, Ugur; Cay, Serkan; Topaloglu, Serkan; Temizhan, Ahmet; Aydogdu, Sinan

    2016-05-01

    We aimed to evaluate the prevalence and prognostic role of fragmented QRS complex (fQRS) in predicting arrhythmic events and cardiovascular mortality in patients with noncompaction cardiomyopathy (NCC). A total of 88 patients (64.8% men, mean age 38.6 ± 17.7 years) with the diagnosis of NCC were enrolled. Median follow-up time was 42.4 months. The fQRS was defined as the presence of ≥1 additional R wave (R') or notch on the R/S waves in ≥2 contiguous leads representing anterior (V1 to V5), inferior (II, III, and aVF), or lateral (I, aVL, and V6) myocardial segments. Compared to patients without fQRS group, patients with fQRS (fQRS (+) group) showed higher rates for total arrhythmic events, ventricular tachycardia, bradyarrhythmia requiring pacemaker, sudden cardiac death, cardiovascular mortality, and all-cause mortality. The cut-off point of ≥3 leads for the fQRS was the optimal point discriminating an arrhythmic event and cardiovascular mortality. In Kaplan-Meier survival analysis, total arrhythmic events and cardiovascular mortality occurred more frequently in the fQRS (+) group. In multivariate Cox proportional hazard regression analysis, after adjusting for other confounding factors, the presence of fQRS were found to be as an independent predictor of arrhythmic events (hazard ratio 3.850, 95% CI 1.062 to 9.947, p = 0.002) and cardiovascular mortality (hazard ratio 2.719, 95% CI 1.494 to 9.262, p = 0.005). In conclusion, the presence of fQRS complex, as a simple and feasible electrocardiographic marker, seems to be a novel predictor of arrhythmic events and cardiovascular mortality in patients with NCC. This simple parameter may be used in identifying patients at high risk for arrhythmic events and so individualization of specific therapies can be applied. PMID:26979479

  9. Homologous Solar Events on 2011 January 27: Build-up and Propagation in a Complex Coronal Environment

    NASA Astrophysics Data System (ADS)

    Pick, M.; Stenborg, G.; Démoulin, P.; Zucca, P.; Lecacheux, A.

    2016-05-01

    In spite of the wealth of imaging observations at the extreme-ultraviolet (EUV), X-ray, and radio wavelengths, there are still relatively few cases where all of the imagery is available to study the full development of a coronal mass ejection (CME) event and its associated shock. The aim of this study is to contribute to the understanding of the role of the coronal environment in the development of CMEs and the formation of shocks, and their propagation. We have analyzed the interactions of a couple of homologous CME events with ambient coronal structures. Both events were launched in a direction far from the local vertical, and exhibited a radical change in their direction of propagation during their progression from the low corona into higher altitudes. Observations at EUV wavelengths from the Atmospheric Imaging Assembly instrument on board the Solar Dynamic Observatory were used to track the events in the low corona. The development of the events at higher altitudes was followed by the white-light coronagraphs on board the Solar and Heliospheric Observatory. Radio emissions produced during the development of the events were well recorded by the Nançay solar instruments. Thanks to their detection of accelerated electrons, the radio observations are an important complement to the EUV imaging. They allowed us to characterize the development of the associated shocks, and helped to unveil the physical processes behind the complex interactions between the CMEs and ambient medium (e.g., compression, reconnection).

  10. Transient Astronomical Events as Inspiration Sources of Medieval Art. III: the 13th and 14th Centuries, and the case of the French "Ordre de L'Étoile"

    NASA Astrophysics Data System (ADS)

    Bònoli, F.; Incerti, M.; Polcaro, V. F.

    2015-05-01

    Going ahead in our long-term project of analysis of the role of transient astronomical events as inspirational sources of medieval art, we extend our interest towards the 13th and 14th centuries, epochs of strong changes either in society, art or science. It is our aim to verify if the relationship we found in the 11th century between the number of artworks where a star is represented, and astonishing transient astronomical events was, in this new situation, still valid. Moreover, in order to check the influence of astronomical events on the 14th-century social and cultural environment, we focus on the case of the Ordre de l'Étoile, a chivalrous society founded by John II of France (Jan le Bon, roi de France) at the end of 1351, looking in ancient chronicles for some relevant contemporary astronomical event as an inspiration source for the "star" in the Order's name, in the garb of its knights and in its motto.

  11. Complex effusive events at Kilauea as documented by the GOES satellite and remote video cameras

    USGS Publications Warehouse

    Harris, A.J.L.; Thornber, C.R.

    1999-01-01

    GOES provides thermal data for all of the Hawaiian volcanoes once every 15 min. We show how volcanic radiance time series produced from this data stream can be used as a simple measure of effusive activity. Two types of radiance trends in these time series can be used to monitor effusive activity: (a) Gradual variations in radiance reveal steady flow-field extension and tube development. (b) Discrete spikes correlate with short bursts of activity, such as lava fountaining or lava-lake overflows. We are confident that any effusive event covering more than 10,000 m2 of ground in less than 60 min will be unambiguously detectable using this approach. We demonstrate this capability using GOES, video camera and ground-based observational data for the current eruption of Kilauea volcano (Hawai'i). A GOES radiance time series was constructed from 3987 images between 19 June and 12 August 1997. This time series displayed 24 radiance spikes elevated more than two standard deviations above the mean; 19 of these are correlated with video-recorded short-burst effusive events. Less ambiguous events are interpreted, assessed and related to specific volcanic events by simultaneous use of permanently recording video camera data and ground-observer reports. The GOES radiance time series are automatically processed on data reception and made available in near-real-time, so such time series can contribute to three main monitoring functions: (a) automatically alerting major effusive events; (b) event confirmation and assessment; and (c) establishing effusive event chronology.

  12. A Model of Spontaneous Complex Tremor Migration Patterns and Background Slow-Slip Events via Interaction of Brittle Asperities and a Ductile Matrix

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Ampuero, J. P.

    2014-12-01

    Slow-slip events (SSE) and tectonic tremors offer a unique window into a broad spectrum of earthquake behavior and fault mechanics at the bottom of seismogenic zones. Our previous heterogeneous fault models composed of brittle asperities embedded in a matrix with velocity weakening-to-strengthening transition reproduced tremor migration patterns observed in the Cascadia subduction zone including forward tremor propagation and Rapid Tremor Reversals (RTRs). Tremors were driven by a background SSE whose existence did not require tremors. Here we assess the importance of feedback between tremors and SSE by considering a ductile (pure velocity-strengthening) background matrix. In this new model complex tremor swarms and SSE result solely from the interaction between brittle asperity failures via intervening transient creep. In particular, in the absence of tremor asperities the model produces no SSE. The new model is less complicated than our previous one and matches some observations better. It reproduces the scale and recurrence interval of large tremor episodes and the migration speed and distance of RTR observed in Cascadia, and the ratio of RTR to forward migration speeds spans a wider range. Observations of tremor-genic and tremor-less slow slip occurring in a same segment of the Cascadia subduction zone suggest that natural faults are in between these two end-member models. We study the tremor-driven SSE model through numerical simulations of heterogeneous rate-and-state faults with mixed velocity-weakening (VW) and velocity-strengthening (VS) materials. We find that the (b-a)*sigma value (effectively the frictional properties and pore pressure) of the VW fault portions determine the criticalness of the whole fault (i.e. its ability to produce spontaneous transient events). A combined analytical and numerical study of fault criticalness as a function of density of VW material and contrast of (b-a)*sigma values reveals subcritical-to-supercritical transitions

  13. Detection of Unusual Events and Trends in Complex Non-Stationary Data Streams

    SciTech Connect

    Perez, Rafael B; Protopopescu, Vladimir A; Worley, Brian Addison; Perez, Cristina

    2006-01-01

    The search for unusual events and trends hidden in multi-component, nonlinear, non-stationary, noisy signals is extremely important for a host of different applications, ranging from nuclear power plant and electric grid operation to internet traffic and implementation of non-proliferation protocols. In the context of this work, we define an unusual event as a local signal disturbance and a trend as a continuous carrier of information added to and different from the underlying baseline dynamics. The goal of this paper is to investigate the feasibility of detecting hidden intermittent events inside non-stationary signal data sets corrupted by high levels of noise, by using the Hilbert-Huang empirical mode decomposition method.

  14. Prediction of the most extreme rainfall events in the South American Andes: A statistical forecast based on complex networks

    NASA Astrophysics Data System (ADS)

    Boers, Niklas; Bookhagen, Bodo; Barbosa, Henrique; Marwan, Norbert; Kurths, Jürgen; Marengo, Jose

    2015-04-01

    During the monsoon season, the subtropical Andes in South America are exposed to spatially extensive extreme rainfall events that frequently lead to flashfloods and landslides with severe socio-economic impacts. Since dynamical weather forecast has substantial problems with predicting the most extreme events (above the 99th percentile), alternative forecast methods are called for. Based on complex network theory, we developed a general mathematical framework for statistical prediction of extreme events in significantly interrelated time series. The key idea of our approach is to make the internal synchronization structure of extreme events mathematically accessible in terms of the topology of a network which is constructed from measuring the synchronization of extreme events at different locations. The application of our method to high-spatiotemporal resolution rainfall data (TRMM 3B42) reveals a migration pattern of large convective systems from southeastern South America towards the Argentinean and Bolivian Andes, against the direction of the northwesterly low-level moisture flow from the Amazon Basin. Once these systems reach the Andes, they lead to spatially extensive extreme events up to elevations above 4000m, leading to substantial risks of associated natural hazards. Based on atmospheric composites, we could identify an intricate interplay of frontal systems approaching from the South, low-level moisture flow from the Amazon Basin to the North, and the Andean orography as responsible climatic mechanism. These insights allow to formulate a simple forecast rule predicting 60% (90% during El Niño conditions) of extreme rainfall events at the eastern slopes of the subtropical Andes. The rule can be computed from readily available rainfall and pressure data and is already being tested by local institutions for disaster preparation.

  15. Synthesis of Diversely Functionalized Oxindoles Enabled by Migratory Insertion of Isocyanide to a Transient σ-Alkylpalladium(II) Complex.

    PubMed

    Kong, Wangqing; Wang, Qian; Zhu, Jieping

    2016-08-01

    Palladium-catalyzed intramolecular carbopalladation of N-aryl acrylamides followed by migratory insertion of an isocyanide-coordinated C(sp(3) )-Pd intermediate afforded an alkylimidoyl-Pd(II) complex, which can be intercepted by a nucleophile, including heteroarenes. In addition to amides, the alkylimidoyl-Pd(II) complex was successfully converted into esters, ketones, and bis-heterocyclic compounds. An unprecedented palladium-catalyzed enantioselective domino process involving isocyanide was also documented. PMID:27356093

  16. Transient Absorption and Time-Resolved Fluorescence Studies of Solvated Ruthenium Di-Bipyridine Pseudo-Halide Complexes

    NASA Astrophysics Data System (ADS)

    Compton, R.; Weidinger, D.; Owrutsky, J. C.

    2012-06-01

    Time-resolved IR and fluorescence measurements were performed to probe the vibrational and electronic properties, respectively, of ruthenium di-bipyridine pseudo-halide (Ru(Bpy){_2}(X){_2} (where X = CN, N{_3} or NCS)) complexes. Vibrational energy relaxation (VER) times were determined for the complexes dissolved in dimethyl sulfoxide (DMSO) with a trend in VER time of NCS > CN > N{_3}. A similar trend and comparable absolute rates for NCS- and N3- were previously observed by our group and others for simple inorganic anions in solution, suggesting a minimal contribution due to complexation. Measurements of the VER time of the CN complex in various solvents provide VER times in ethanol (42.3 ps) and DMSO (53.3 ps), which shows that protic solvents promote the relaxation. Time-resolved fluorescence measurements indicate a strong ligand dependence, with a factor of five decrease in the excited electronic state decay time from the CN (215 ns) to the NCS (39 ns) complex. A solvent dependence of the CN complex reveals a nearly 3-fold increase in the fluorescence decay time from acetonitrile (70 ns) to DMSO (215 ns).

  17. Transient behavior in the Lorenz model

    NASA Astrophysics Data System (ADS)

    Kravtsov, S.; Sugiyama, N.; Tsonis, A. A.

    2014-12-01

    Dynamical systems like the one described by the three-variable Lorenz model may serve as metaphors for complexity in nature. When natural systems are perturbed by external forcing factors, they tend to relax back to their equilibrium conditions after the forcing has shut off. Here we investigate the behavior of such transients in the Lorenz model by studying its trajectories initialized far away from the asymptotic attractor. Perhaps somewhat surprisingly, these transient trajectories exhibit complex routes and, among other things, sensitivity to initial conditions akin to that of the asymptotic behavior on the attractor. Thus, similar extreme events may lead to widely different variations before the perturbed system returns back to its statistical equilibrium.

  18. Cluster synchronization of complex networks via event-triggered strategy under stochastic sampling

    NASA Astrophysics Data System (ADS)

    Hu, Aihua; Cao, Jinde; Hu, Manfeng; Guo, Liuxiao

    2015-09-01

    This paper is concerned with the issue of mean square cluster synchronization of non-identical nodes connected by a directed network. Suppose that the nodes possess nonlinear dynamics and split into several clusters, then an event-triggered control scheme is proposed for synchronization based on the information from stochastic sampling. Meanwhile, an equilibrium is considered to be the synchronization state or the virtual leader for each cluster, which can apply pinning control to the following nodes. Assume that a spanning tree exists in the subgraph consisting of the nodes belonging to the same cluster and the corresponding virtual leader, and the instants for updating controllers are determined by the given event-triggered strategy, then some sufficient conditions for cluster synchronization are presented according to the Lyapunov stability theory and linear matrix inequality technique. Finally, a specific numerical example is shown to demonstrate the effectiveness of the theoretical results.

  19. Transient 120,000-year response of the large regional flow system at Yucca Mountain, Nevada to complex cyclical variability in paleoclimate

    NASA Astrophysics Data System (ADS)

    Park, Y.; Schwartz, F. W.; Sudicky, E. A.; McLaren, R. G.; Huber, M.; Apted, M.

    2009-12-01

    A regional flow model is used to explore the transient behavior of a flow system at Yucca Mountain due to a significant variability in Pleistocene and Holocene climates. Simulations involve a 39 km slice of the Death Valley Flow System through Yucca Mountain toward the Amargosa Desert. The long time scale over which infiltration has changed (tens-of-thousands of years) is matched by the large physical extent of the flow system (many tens-of-kilometers). Paleo-infiltration rates were estimated using a juniper pollen percentage that extends from the last interglacial period (approximately 120 ka BP) to present. Flow and 14C transport simulations show that the flow system changes markedly as a function of paleoclimate. At the last glacial maximum (20 ka BP), the recharge to the flow system was about an order-of-magnitude higher than present and water table was more than 100 meters higher. With large basin time constants, flow is complicated because hydraulic heads at a given location reflect conditions of the past, but at another location the flow may reflect present conditions. This complexity is also manifested by processes that depend on flow, for example 14C transport. Without a model that accounts for the historical transients in recharge for at least the last 20,000 years, there is no simple way to deconvolve the 14C dates to explain patterns of flow.

  20. Nonlinear Transient Analysis and Design of Complex Engineering Structures for Worst Case Accidents : Experience from Industrial and Military Applications

    NASA Astrophysics Data System (ADS)

    Ibrahimbegovic, Adnan; Brancherie, D.; Colliat, J.-B.; Davenne, L.; Dominguez, N.; Herve, G.; Villon, P.

    In this work we address some of the present threats posed to engineering structures in placing them under extreme loading conditions. The common ground for the problems studied herein from the viewpoint of structural integrity is their transient nature characterized by different time scales and the need to evaluate the consequence for a high level of uncertainty in quantifying the cause. The pertinent issues are studied in detail for three different model problems: i) the worstcase scenario of system functioning failure accident in a nuclear power plant causing the loss of cooling liquid, ii) the terrorist attacks brought explosion and impact of large aeroplane on a massive structure, iii) devastating fire and sustained high temperatures effects on massive cellular structures. By using these case studies, we discuss the issues related to multi-scale modelling of inelastic damage mechanisms for massive structures, as well as the issues pertaining to the time integration schemes in presence of different scales in time variation of different sub-problems brought by a particular nature of loading (both for a very short and a very long loading duration) and finally the issues related to model reduction seeking to provide an efficient and yet sufficiently reliable basis for parametric studies employed within the framework of a design procedure. Several numerical simulations are presented in order to further illustrate the approaches proposed herein. Concluding remarks are stated regarding the current and future research in this domain.

  1. A computer code for multiphase all-speed transient flows in complex geometries. MAST version 1.0

    NASA Technical Reports Server (NTRS)

    Chen, C. P.; Jiang, Y.; Kim, Y. M.; Shang, H. M.

    1991-01-01

    The operation of the MAST code, which computes transient solutions to the multiphase flow equations applicable to all-speed flows, is described. Two-phase flows are formulated based on the Eulerian-Lagrange scheme in which the continuous phase is described by the Navier-Stokes equation (or Reynolds equations for turbulent flows). Dispersed phase is formulated by a Lagrangian tracking scheme. The numerical solution algorithms utilized for fluid flows is a newly developed pressure-implicit algorithm based on the operator-splitting technique in generalized nonorthogonal coordinates. This operator split allows separate operation on each of the variable fields to handle pressure-velocity coupling. The obtained pressure correction equation has the hyperbolic nature and is effective for Mach numbers ranging from the incompressible limit to supersonic flow regimes. The present code adopts a nonstaggered grid arrangement; thus, the velocity components and other dependent variables are collocated at the same grid. A sequence of benchmark-quality problems, including incompressible, subsonic, transonic, supersonic, gas-droplet two-phase flows, as well as spray-combustion problems, were performed to demonstrate the robustness and accuracy of the present code.

  2. Using rain-on-snow events to evaluate the quality of bias correction to represent complex inter-variable dependencies

    NASA Astrophysics Data System (ADS)

    Rössler, Ole; Bosshard, Thomas; Weingartner, Rolf

    2016-04-01

    A key issue for adaptation planning is the information of projections about changes of extremes. Climate projections of meteorological extremes and their downscaling are a challenge on their own. Yet - at least in hydrology - meteorological extremes are not necessarily hydrological extremes. These can also result from a sequence of days with only moderate meteorological conditions, too. This sequences are called "storylines". In climate change impact assess studies it is relevant to know, whether these meteorological storylines are represented in regional climate models, and how well can bias correction preserve or improve the representation. One storyline leading to hydrological extremes are rain-on-snow events, and more specifically rain-on-snowfall events. These events challenge the regional climate model and the bias correction in terms of representing absolute values and inter-variable dependences. This study makes use of the rain-on-snow-storylines to evaluate the performance of regional climate models and a bias correction method in reproducing complex inter-variable dependencies. At first, we applied a hydrological model to a mesoscale catchment in Switzerland that is known to be effected by rain-on-snow events. At second, the ERA-Interim driven regional climate model RCA4.5 - developed at SMHI - with a spatial resolution of 0.11 * 0.11 degree was used to drive the hydrological model. At third, bias-correction of the RCM was done applying the distribution based scaling (DBS) bias-correction method (Yang et al., 2010) developed at the SMHI. The bias-corrected data then also served as driving input data to the hydrological model. Based on the simulated runoff, as well as simulated precipitation, temperature, and snow pack data, an algorithm to detect rain-on-snow events was applied. Finally, the presence or absents of rain-on-snow events for the three different climate input data, ERA.RCA4.5, DBS corrected ERA.RC4 and observed climate, are evaluated within

  3. Determining the Total Volume of the 2.05 Ga Bushveld Magmatic Event: Correlation of the Molopo Farms Complex, Botswana

    NASA Astrophysics Data System (ADS)

    Escobar, E.; Gates, M.; Pitcavage, E.; Bybee, G. M.; Feineman, M. D.

    2015-12-01

    The Bushveld Igneous Complex (BIC) in South Africa, erupted 2.05 billion years ago, is the world's largest layered intrusion in the range of 710-1060 x 103 km3 conservatively. However, the total volume of the magmatic event that produced the BIC remains poorly known. Several other intrusions occurred approximately contemporaneously with the BIC, but a clear relationship between these multiple intrusions is yet to be determined. The Molopo Farms Complex (MFC) is a layered igneous complex of similar age 2.044 Ga ­± 24 Ma located in Botswana, 200km west of the far western limb of the BIC, with a total volume of 1300 km2. Using trace element analysis, this study makes an attempt to find a correlation between the magma that emplaced the Molopo Farms Complex with the Bushveld Igneous Complex. The MFC is related to the BIC and is located under approximately 200m of Kalahari sands, which prevents any direct sampling or observation. Unlike the BIC, the MFC is poorly studied creating a lack of information for the complex. Drill core samples from the MFC were analyzed to determine the trace element composition using an inductively coupled plasma mass spectrometer (ICP-MS). Using previously reported values for the BIC; a comparison can be made on both complexes to find possible correlations. The comparison of trace element schematics in the MFC and the BIC suggest that both complexes are derived from the same parental magma, often referred to as the "B1" magma. These comparisons allow for an assumption that the initial parental magma of the BIC may have also emplaced the MFC.

  4. Extensive complex odontoma in the maxillary sinus pushing 3rd molar near the orbital floor causing transient diplopia and chronic sinusitis: a rare presentation and surgical management.

    PubMed

    Gupta, Monika; Das, Debdutta

    2015-03-01

    Odontoma is a mixed odontogenic hamartoma involving both epithelial and mesenchymal tissues. If left untreated, it can lead to complications in certain conditions. Here is a rare presentation of an extensive complex odontoma in maxillary sinus pushing third molar near the orbital floor causing transient diplopia in upward gaze occasionally and chronic sinusitis. Although odontomata are not uncommon and are familiar to practitioners, but some aggressive cases may cause problematic sequelae. Even postoperative complications may result if oral surgeons are not aware of the potential pitfalls associated with the surgical removal of large maxillary antrum odontomata. This article reports a rare presentation which can be considered unique because when obstruction of sinus drainage is evident, serious complications such as orbital infections, epidural and subdural empyema, meningitis, cerebritis, cavernous sinus thrombosis, brain abscess and death can occur. It also addresses points and pitfalls concerning surgery to remove odontoma. PMID:25848139

  5. METEOROLOGICAL EVENTS THAT PRODUCED THE HIGHEST GROUND-LEVEL CONCENTRATIONS DURING COMPLEX TERRAIN FIELD EXPERIMENTS

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) is sponsoring the Complex Terrain Model Development project, a multi-year study to develop improved models for calculating ground-level air pollutant concentrations that result from large emission sources located in mountainous terra...

  6. Incorporating Love- and Rayleigh-wave magnitudes, unequal earthquake and explosion variance assumptions and interstation complexity for improved event screening

    SciTech Connect

    Anderson, Dale N; Bonner, Jessie L; Stroujkova, Anastasia; Shumway, Robert

    2009-01-01

    Our objective is to improve seismic event screening using the properties of surface waves, We are accomplishing this through (1) the development of a Love-wave magnitude formula that is complementary to the Russell (2006) formula for Rayleigh waves and (2) quantifying differences in complexities and magnitude variances for earthquake and explosion-generated surface waves. We have applied the M{sub s} (VMAX) analysis (Bonner et al., 2006) using both Love and Rayleigh waves to events in the Middle East and Korean Peninsula, For the Middle East dataset consisting of approximately 100 events, the Love M{sub s} (VMAX) is greater than the Rayleigh M{sub s} (VMAX) estimated for individual stations for the majority of the events and azimuths, with the exception of the measurements for the smaller events from European stations to the northeast. It is unclear whether these smaller events suffer from magnitude bias for the Love waves or whether the paths, which include the Caspian and Mediterranean, have variable attenuation for Love and Rayleigh waves. For the Korean Peninsula, we have estimated Rayleigh- and Love-wave magnitudes for 31 earthquakes and two nuclear explosions, including the 25 May 2009 event. For 25 of the earthquakes, the network-averaged Love-wave magnitude is larger than the Rayleigh-wave estimate. For the 2009 nuclear explosion, the Love-wave M{sub s} (VMAX) was 3.1 while the Rayleigh-wave magnitude was 3.6. We are also utilizing the potential of observed variances in M{sub s} estimates that differ significantly in earthquake and explosion populations. We have considered two possible methods for incorporating unequal variances into the discrimination problem and compared the performance of various approaches on a population of 73 western United States earthquakes and 131 Nevada Test Site explosions. The approach proposes replacing the M{sub s} component by M{sub s} + a* {sigma}, where {sigma} denotes the interstation standard deviation obtained from the

  7. Horizontal Gene Transfers from Bacteria to Entamoeba Complex: A Strategy for Dating Events along Species Divergence.

    PubMed

    Romero, Miguel; Cerritos, R; Ximenez, Cecilia

    2016-01-01

    Horizontal gene transfer has proved to be relevant in eukaryotic evolution, as it has been found more often than expected and related to adaptation to certain niches. A relatively large list of laterally transferred genes has been proposed and evaluated for the parasite Entamoeba histolytica. The goals of this work were to elucidate the importance of lateral gene transfer along the evolutionary history of some members of the genus Entamoeba, through identifying donor groups and estimating the divergence time of some of these events. In order to estimate the divergence time of some of the horizontal gene transfer events, the dating of some Entamoeba species was necessary, following an indirect dating strategy based on the fossil record of plausible hosts. The divergence between E. histolytica and E. nuttallii probably occurred 5.93 million years ago (Mya); this lineage diverged from E. dispar 9.97 Mya, while the ancestor of the latter separated from E. invadens 68.18 Mya. We estimated times for 22 transferences; the most recent occurred 31.45 Mya and the oldest 253.59 Mya. Indeed, the acquisition of genes through lateral transfer may have triggered a period of adaptive radiation, thus playing a major role in the evolution of the Entamoeba genus. PMID:27239333

  8. Horizontal Gene Transfers from Bacteria to Entamoeba Complex: A Strategy for Dating Events along Species Divergence

    PubMed Central

    Romero, Miguel; Ximenez, Cecilia

    2016-01-01

    Horizontal gene transfer has proved to be relevant in eukaryotic evolution, as it has been found more often than expected and related to adaptation to certain niches. A relatively large list of laterally transferred genes has been proposed and evaluated for the parasite Entamoeba histolytica. The goals of this work were to elucidate the importance of lateral gene transfer along the evolutionary history of some members of the genus Entamoeba, through identifying donor groups and estimating the divergence time of some of these events. In order to estimate the divergence time of some of the horizontal gene transfer events, the dating of some Entamoeba species was necessary, following an indirect dating strategy based on the fossil record of plausible hosts. The divergence between E. histolytica and E. nuttallii probably occurred 5.93 million years ago (Mya); this lineage diverged from E. dispar 9.97 Mya, while the ancestor of the latter separated from E. invadens 68.18 Mya. We estimated times for 22 transferences; the most recent occurred 31.45 Mya and the oldest 253.59 Mya. Indeed, the acquisition of genes through lateral transfer may have triggered a period of adaptive radiation, thus playing a major role in the evolution of the Entamoeba genus. PMID:27239333

  9. Origin of chaotic transients in excitatory pulse-coupled networks.

    PubMed

    Zou, Hai-Lin; Li, Menghui; Lai, Choy-Heng; Lai, Ying-Cheng

    2012-12-01

    We develop an approach to understanding long chaotic transients in networks of excitatory pulse-coupled oscillators. Our idea is to identify a class of attractors, sequentially active firing (SAF) attractors, in terms of the temporal event structure of firing and receipt of pulses. Then all attractors can be classified into two groups: SAF attractors and non-SAF attractors. We establish that long transients typically arise in the transitional region of the parameter space where the SAF attractors are collectively destabilized. Bifurcation behavior of the SAF attractors is analyzed to provide a detailed understanding of the long irregular transients. Although demonstrated using pulse-coupled oscillator networks, our general methodology may be useful in understanding the origin of transient chaos in other types of networked systems, an extremely challenging problem in nonlinear dynamics and complex systems. PMID:23368031

  10. DNA acts as a nucleation site for transient cavitation in the ultrasonic nebulizer.

    PubMed

    Lentz, Y K; Anchordoquy, T J; Lengsfeld, C S

    2006-03-01

    Several new technologies based upon ultrasound technology have been proposed as a method to enhance the delivery of genetic therapeutics. Using ultrasonic nebulization and a well-established method to quantitatively monitor transient cavitation, this study investigates the extent and factors influencing the degradation of DNA. Results from our studies show that the presence of DNA greatly enhances cavitation, and that the number of transient cavitation events also increases with the hydrodynamic diameter and number of DNA molecules in solution. More importantly, removing saturated gases from the plasmid DNA solutions resulted in a decrease in transient cavitation events but not degradation rate, suggesting that the cavitation event responsible for degradation occurs locally at the DNA molecule. Finally, complexing plasmid DNA with the cationic polymer polyethylenimine protected the native structure by reducing the molecule's potential to act as a heterogeneous nucleation site for transient cavitation. PMID:16432878

  11. Heinrich events modeled with a coupled complex ice sheet-climate model

    NASA Astrophysics Data System (ADS)

    Ziemen, Florian; Rodehacke, Christian; Mikolajewicz Mikolajewicz, Uwe

    2013-04-01

    We investigate glacial climate variability with a coupled ice sheet model (ISM) - atmosphere-ocean-vegetation general circulation model (AOVGCM) system, focusing on one of the most prominent features of glacial climate variability, the Heinrich events. Modeling past climates and periods of past climate change is an important test of the capability of climate models to correctly represent future climate changes. Only if we can correctly represent past climates and climate changes, we can be confident about our predictions of future climate changes. We show results from two experiments: (1) a steady-state LGM experiment where the ice sheet model is accelerated by a factor of 10 compared to the climate model covering 30 kyrs in the ISM (3 kyrs in the AOVGCM) and (2) a synchronously coupled experiment focusing in on one ice sheet collapse covering 3.2 kyrs in both models. For the experiments, we coupled a modified version of the Parallel Ice Sheet Model (mPISM) bidirectionally with the AOVGCM ECHAM5/MPIOM/LPJ. ECHAM5 and LPJ were run in T31 resolution (~ 3.75°), MPIOM on a grid with a nominal resolution of 3° and poles over Greenland and Antarctica, mPISM on a 20 km grid covering most of the northern hemisphere. In the models, as well as in the coupling, no flux correction or anomaly maps are applied. The ice sheet surface mass balance is computed using a positive degree day scheme with lapse rate correction and height desertification effect. In the experiments, the surges of the Hudson Strait Ice Stream reach discharge rates of 60000 m3/s and show a typical recurrence interval of 7 kyrs, matching the basic characteristics for Heinrich events inferred from proxy data. The surges are consequences of an internal instability mechanism suggested by MacAyeal (1993) and various parts of the ice sheets show repeated surging. The large ice discharge during a surge of the Hudson Strait Ice Stream causes an expansion of the sea ice cover in the Labrador Sea and the adjacent

  12. Structural dynamics of nitrosylruthenium isomeric complexes studied with steady-state and transient pump-probe infrared spectroscopies.

    PubMed

    Zhao, Yan; Yang, Fan; Wang, Jianru; Yu, Pengyun; Pan, Huifen; Wang, Hongfei; Wang, Jianping

    2016-09-01

    The characteristic nitrosyl stretching (NO) in the region of 1800-1900cm(-1) was used to study the geometric and ligand effect on two nitrosylruthenium complexes, namely [Ru(OAc)(2QN)2NO] (QN=2-chloro-8-quinolinol (H2cqn) or QN=2-methyl-8-quinolinol (H2mqn)). The NO stretching frequency (νNO) was found in the following order: νcis-1 (2cqn)>νcis-2 (2cqn)>νcis-1 (2mqn)>νtrans (2mqn). The results exhibited a spectral sensitivity of the NO mode to both charge distribution and ligand arrangement, which was supported by ab initio computations and natural bond orbital (NBO) analyses. Further, the vibrational population of the vibrationally excited NO stretching mode was found to relax on the order of 7-10ps, showing less than 30% variation from one isomer to another, which were explained on the basis of NO local structures and solute-solvent interactions in these isomeric nitrosylruthenium complexes. PMID:27209490

  13. Structural dynamics of nitrosylruthenium isomeric complexes studied with steady-state and transient pump-probe infrared spectroscopies

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Yang, Fan; Wang, Jianru; Yu, Pengyun; Pan, Huifen; Wang, Hongfei; Wang, Jianping

    2016-09-01

    The characteristic nitrosyl stretching (NO) in the region of 1800-1900 cm- 1 was used to study the geometric and ligand effect on two nitrosylruthenium complexes, namely [Ru(OAc)(2QN)2NO] (QN = 2-chloro-8-quinolinol (H2cqn) or QN = 2-methyl-8-quinolinol (H2mqn)). The NO stretching frequency (νNO) was found in the following order: νcis-1 (2cqn) > νcis-2 (2cqn) > νcis-1 (2mqn) > νtrans (2mqn). The results exhibited a spectral sensitivity of the NO mode to both charge distribution and ligand arrangement, which was supported by ab initio computations and natural bond orbital (NBO) analyses. Further, the vibrational population of the vibrationally excited NO stretching mode was found to relax on the order of 7-10 ps, showing less than 30% variation from one isomer to another, which were explained on the basis of NO local structures and solute-solvent interactions in these isomeric nitrosylruthenium complexes.

  14. Early Oligocene geomagnetic field behavior from ODP Site 1128: Complex records of short-period polarity events

    NASA Astrophysics Data System (ADS)

    Molina-Garza, R. S.; Fuller, M. D.

    2001-12-01

    At Site 1128, in the Great Australian Bight, Leg 182 of the Ocean Drilling Program recovered a thick (~350 m) section of Upper Eocene and Lower Oligocene marine calcareous clays. Shipboard measurements established a magnetostratigraphy that can unambiguously be correlated to chrons C13n to C10n of the global polarity time scale (GPTS), and a less complete record of chrons C17n to C15r (due to poor core recovery). Correlation to the GPTS is further supported by available biostratigraphic data. For the Lower Oligocene sequence, average sedimentation rate is estimated at ~4 cm/kyr. The sediments recovered thus allow to test for the completeness and reliability of the geomagnetic field polarity during the Early Oligocene. The original shipboard long-core measurements suggested the presence of additional short polarity events or geomagnetic field excursions during chrons C13n, C12r, C11r, and C11n. In order to examine the reliability of the record and the nature of possible short-polarity events, we obtained discrete samples from the entire sequence at ~1 m intervals, with a closer sample spacing in critical intervals (~10 cm). The natural remanence of these sediments is normally simple. After removing a small soft overprint, the magnetization decays towards the origin with distributed coercivities and distributed unblocking temperatures. Demagnetization behavior and other rock magnetic data indicate that the remanence resides primarily in a cubic phase such as magnetite or maghemite, with a small contribution from hematite. Discrete samples from chron C12r did not reproduce the long-core record for two of the supposed events, single samples suggest the presence of short events or cryptochrons near the base of both C13n and C12r, and multiple samples suggest the existence of short-period normal polarity events during C11r and near the top of C12r. The records of these events are, however, complex. Demagnetization results indicate that the magnetization consists of an

  15. Bézier curve string method for the study of rare events in complex chemical systems

    NASA Astrophysics Data System (ADS)

    Bellucci, Michael A.; Trout, Bernhardt L.

    2014-08-01

    We present a new string method for finding the most probable transition pathway and optimal reaction coordinate in complex chemical systems. Our approach evolves an analytic parametric curve, known as a Bézier curve, to the most probable transition path between metastable regions in configuration space. In addition, we demonstrate that the geometric properties of the Bézier curve can be used to construct the optimal reaction coordinate near the most probable reaction path, and can further be used to devise a ranking vector capable of identifying precisely which collective variables are most important for governing the transition between metastable states. We discuss the algorithmic details of the Bézier curve string method, analyze its stability, accuracy and efficiency, and illustrate its capabilities using model potential energy functions. In particular, we use the degree elevation property of Bézier curves to develop an algorithm that adaptively learns the degree polynomial necessary to accurately represent the most probable transition path. Subsequently, we apply our method to the isomerization of alanine dipeptide, and demonstrate that the reaction coordinate obtained from the Bézier curve string method is in excellent agreement with the optimal reaction coordinate constructed from an aimless shooting and maximum likelihood procedure. Finally, we apply our method to a large complex system and study the homogenous nucleation of benzene from the melt. In these two examples, we illustrate that the ranking vector correctly identifies which collective variables govern these chemical transitions.

  16. Tripeptide-copper complex GHK-Cu (II) transiently improved healing outcome in a rat model of ACL reconstruction.

    PubMed

    Fu, Sai-Chuen; Cheuk, Yau-Chuk; Chiu, Wai-Yin Vivien; Yung, Shu-Hang; Rolf, Christer G; Chan, Kai-Ming

    2015-07-01

    After anterior cruciate ligament reconstruction (ACLR), the biological healing of the graft is a rate-limiting step which can contribute to graft failure. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu(II) (GHK-Cu) is a well-known activator of tissue remodeling. We investigated whether GHK-Cu can improve graft healing following ACLR. Seventy-two rats underwent unilateral ACLR were randomized to saline, 0.3 or 3 mg/ml GHK-Cu groups (n = 24). Post-operational intra-articular injections were given from week 2, once a week, for 4 weeks. Gait analysis was performed pre-injury and at harvesting time. At 6 or 12 weeks post-operation, knee specimens were harvested for knee laxity test, graft pull-out test, and histology. At 6 weeks post-ACLR, GHK-Cu groups resulted in a smaller side-to-side difference in knee laxity as compared to the saline group (p = 0.009), but there was no significant difference at 12 weeks post-operation. The graft complex in the 0.3 mg/ml GHK-Cu group had higher stiffness than saline group at 6 weeks post-operation (p = 0.026), but there was no significant difference in ultimate load, gait parameters, and histological scores among treatment groups. All grafts failed mid-substance during pull-out test. Intra-articular supplementation with a bioactive small molecule GHK-Cu improved graft healing following ACLR in rat, but the beneficial effects could not last as treatment discontinued. PMID:25731775

  17. Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

    PubMed Central

    Fidler, Andrew F.; Singh, Ved P.; Long, Phillip D.; Dahlberg, Peter D.; Engel, Gregory S.

    2013-01-01

    Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex. PMID:24160544

  18. Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

    SciTech Connect

    Fidler, Andrew F.; Singh, Ved P.; Engel, Gregory S.; Long, Phillip D.; Dahlberg, Peter D.

    2013-10-21

    Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

  19. TP53 mutations are early events in chronic lymphocytic leukemia disease progression and precede evolution to complex karyotypes.

    PubMed

    Lazarian, Gregory; Tausch, Eugen; Eclache, Virginie; Sebaa, Amel; Bianchi, Vincent; Letestu, Remi; Collon, Jean-Francois; Lefebvre, Valerie; Gardano, Laura; Varin-Blank, Nadine; Soussi, Thierry; Stilgenbauer, Stephen; Cymbalista, Florence; Baran-Marszak, Fanny

    2016-10-15

    TP53 abnormalities lead to resistance to purine analogues and are found in over 40% of patients with refractory chronic lymphocytic leukemia (CLL). At diagnosis, no more than 5% of patients carry the 17p deletion, most cases harbour mutations within the other TP53 allele. The incidence of a TP53 mutation as the only alteration is approximately 5%, but this depends on the sensitivity of the technique. Recently, having a complex karyotype has been considered a strong adverse prognostic factor. However, there are no longitudinal studies simultaneously examining the presence of the 17p deletion, TP53 mutations and karyotype abnormalities. We conducted a retrospective longitudinal study of 31 relapsed/refractory CLL patients. Two to six blood samples per patient were analyzed, with a median follow-up of 8 years. In this report, we assessed the sequence of events of TP53 clonal evolution and correlated the presence of TP53 abnormalities to genetic instability during progression and treatment. Next-generation sequencing allowed the early detection of TP53 mutated clones and was able to be performed on a routine basis, demonstrating an excellent correlation between the Illumina and Ion Torrent technologies. We concluded that TP53 mutations are early events and precede clonal evolution to complex karyotypes. We strongly recommend the early and iterated detection of TP53 mutations in progressive cases. PMID:27270786

  20. Complex Socio-Ecological Dynamics driven by extreme events in the Amazon

    NASA Astrophysics Data System (ADS)

    Pinho, P. F.

    2015-12-01

    Several years with extreme floods or droughts in the past decade have caused human suffering in remote communities of the Brazilian Amazon. Despite documented local knowledge and practices for coping with the high seasonal variability characteristic of the region's hydrology (e.g. 10m change in river levels between dry and flood seasons), and despite 'civil Defense' interventions by various levels of government, the more extreme years seem to have exceeded the coping capacity of the community. In this paper, we explore whether there is a real increase in variability, whether the community perceives that recent extreme events are outside the experience which shapes their responses to 'normal' levels of variability, and what science-based policy could contribute to greater local resilience. Hydrological analyses suggest that variability is indeed increasing, in line with expectations from future climate change. However, current measures of hydrological regimes do not predict years with social hardship very well. Interviewees in two regions are able to express their strategies for dealing with 'normal' variability very well, but also identify ways in which abnormal years exceed their ability to cope. Current Civil Defense arrangements struggle to deliver emergency assistance in a sufficiently timely and locally appropriate fashion. Combining these insights in the context of social-ecological change, we suggest how better integration of science, policy and local knowledge could improve resilience to future trends, and identify some contributions science could make into such an arrangement.

  1. The event-related brain potential as an index of attention allocation in complex displays

    NASA Technical Reports Server (NTRS)

    Wickens, C. D.; Heffley, E. F.; Kramer, A. F.; Donchin, E.

    1980-01-01

    The advantages of employing the event-related brain potential (ERP) in the assessment of allocation of attention in dynamic environments are discussed. Three experiments are presented in which the P300 component of the ERP is demonstrated to be a useful index of subjects' locus of attention. The first two experiments were concerned with the allocation of attention during discrete and continuous visual monitoring tasks. The results indicated that a P300 was elicited only by stimuli to which the subject had to attend in order to perform successfully the task. The third experiment was conducted to assess the sensitivity of P300 to the manner in which attention is allocated to different aspects of a display during the performance of a 3-dimensional target acquisition task. The amplitude of the P300 was found to reflect differences between two levels of workload, as well as the task relevance of the stimuli. The results of the experiments are discussed in terms of their utility in the evaluation of the design of man-machine systems as well as in the study of the allocation of attention in operational environments.

  2. Dynamic studies of H-Ras•GTPγS interactions with nucleotide exchange factor Sos reveal a transient ternary complex formation in solution

    PubMed Central

    Vo, Uybach; Vajpai, Navratna; Embrey, Kevin J.; Golovanov, Alexander P.

    2016-01-01

    The cycling between GDP- and GTP- bound forms of the Ras protein is partly regulated by the binding of Sos. The structural/dynamic behavior of the complex formed between activated Sos and Ras at the point of the functional cycle where the nucleotide exchange is completed has not been described to date. Here we show that solution NMR spectra of H-Ras∙GTPγS mixed with a functional fragment of Sos (SosCat) at a 2:1 ratio are consistent with the formation of a rather dynamic assembly. H-Ras∙GTPγS binding was in fast exchange on the NMR timescale and retained a significant degree of molecular tumbling independent of SosCat, while SosCat also tumbled largely independently of H-Ras. Estimates of apparent molecular weight from both NMR data and SEC-MALS revealed that, at most, only one H-Ras∙GTPγS molecule appears stably bound to Sos. The weak transient interaction between Sos and the second H-Ras∙GTPγS may provide a necessary mechanism for complex dissociation upon the completion of the native GDP → GTP exchange reaction, but also explains measurable GTP → GTP exchange activity of Sos routinely observed in in vitro assays that use fluorescently-labelled analogs of GTP. Overall, the data presents the first dynamic snapshot of Ras functional cycle as controlled by Sos. PMID:27412770

  3. Dynamic studies of H-Ras•GTPγS interactions with nucleotide exchange factor Sos reveal a transient ternary complex formation in solution.

    PubMed

    Vo, Uybach; Vajpai, Navratna; Embrey, Kevin J; Golovanov, Alexander P

    2016-01-01

    The cycling between GDP- and GTP- bound forms of the Ras protein is partly regulated by the binding of Sos. The structural/dynamic behavior of the complex formed between activated Sos and Ras at the point of the functional cycle where the nucleotide exchange is completed has not been described to date. Here we show that solution NMR spectra of H-Ras∙GTPγS mixed with a functional fragment of Sos (Sos(Cat)) at a 2:1 ratio are consistent with the formation of a rather dynamic assembly. H-Ras∙GTPγS binding was in fast exchange on the NMR timescale and retained a significant degree of molecular tumbling independent of Sos(Cat), while Sos(Cat) also tumbled largely independently of H-Ras. Estimates of apparent molecular weight from both NMR data and SEC-MALS revealed that, at most, only one H-Ras∙GTPγS molecule appears stably bound to Sos. The weak transient interaction between Sos and the second H-Ras∙GTPγS may provide a necessary mechanism for complex dissociation upon the completion of the native GDP → GTP exchange reaction, but also explains measurable GTP → GTP exchange activity of Sos routinely observed in in vitro assays that use fluorescently-labelled analogs of GTP. Overall, the data presents the first dynamic snapshot of Ras functional cycle as controlled by Sos. PMID:27412770

  4. An evaluation of the PENCURV model for penetration events in complex targets.

    SciTech Connect

    Broyles, Todd P.

    2004-07-01

    Three complex target penetration scenarios are run with a model developed by the U. S. Army Engineer Waterways Experiment Station, called PENCURV. The results are compared with both test data and a Zapotec model to evaluate PENCURV's suitability for conducting broad-based scoping studies on a variety of targets to give first order solutions to the problem of G-loading. Under many circumstances, the simpler, empirically based PENCURV model compares well with test data and the much more sophisticated Zapotec model. The results suggest that, if PENCURV were enhanced to include rotational acceleration in its G-loading computations, it would provide much more accurate solutions for a wide variety of penetration problems. Data from an improved PENCURV program would allow for faster, lower cost optimization of targets, test parameters and penetration bodies as Sandia National Laboratories continues in its evaluation of the survivability requirements for earth penetrating sensors and weapons.

  5. The Transient Universe

    NASA Astrophysics Data System (ADS)

    Shappee, Benjamin John

    When one looks at the night sky, one usually gets the impression of a static and constant universe. Quite apart from appearances, the sky is teeming with violent, variable, and transient events that shape our universe. These capricious objects are not only penetrating probes into physical conditions too extreme for earthbound laboratories, but they are also useful tools to measure the universe. In this dissertation, I investigate the observational and theoretical properties of three classes of transient/variable objects: thermonuclear supernovae, Cepheid variable stars, and active galactic nuclei.

  6. The nature of the longest transients detected by Swift

    NASA Astrophysics Data System (ADS)

    Starling, Rhaana

    2012-10-01

    We propose rapid XMM-Newton observations of the next exceptionally long Swift BAT triggered transient, in order to understand the nature of these anomalous systems. XMM is able to disentangle the complex spectra and track the evolution of early thermal emission at times when the sources become too faint for similar analysis with Swift XRT. These events are reshaping our view of the transient high energy Universe, and may be the first examples of Ic supernova shock breakout and rare stellar mergers. Yet to firmly establish their origins we must probe the central engines with deeper X-ray spectral coverage.

  7. Ligand-specific, transient interaction between integrins and calreticulin during cell adhesion to extracellular matrix proteins is dependent upon phosphorylation/dephosphorylation events.

    PubMed Central

    Coppolino, M G; Dedhar, S

    1999-01-01

    As transmembrane heterodimers, integrins bind to both extracellular ligands and intracellular proteins. We are currently investigating the interaction between integrins and the intracellular protein calreticulin. A prostatic carcinoma cell line (PC-3) was used to demonstrate that calreticulin can be found in the alpha3 immunoprecipitates of cells plated on collagen type IV, but not when plated on vitronectin. Conversely, alphav immunoprecipitates contained calreticulin only when cells were plated on vitronectin, i. e. not when plated on collagen IV. The interactions between these integrins and calreticulin were independent of actin cytoskeleton assembly and were transient, being maximal approx. 10-30 min after the cells came into contact with the substrates prior to complete cell spreading and formation of firm adhesive contacts. We demonstrate that okadaic acid, an inhibitor of intracellular serine/threonine protein phosphatases, inhibited the alpha3beta1-mediated adhesion of PC-3 cells to collagen IV and the alpha2beta1-mediated attachment of Jurkat cells to collagen I. This inhibition by okadaic acid was accompanied by inhibition of the ligand-specific interaction of calreticulin with the respective integrins in the two cell types. Additionally, we found that pharmacological inhibition of mitogen-activated protein kinase kinase (MEK) resulted in prolongation of the calreticulin-integrin interaction, and enhancement of PC-3 cell attachment to collagen IV. We conclude that calreticulin interacts transiently with integrins during cell attachment and spreading. This interaction depends on receptor occupation, is ligand-specific, and can be modulated by protein phosphatase and MEK activity. PMID:10229657

  8. Ultrastructural midgut events in Culicidae larvae fed with Bacillus sphaericus 2297 spore/crystal complex.

    PubMed

    Charles, J F

    1987-01-01

    Ingestion of Bacillus sphaericus 2297 spore/crystal complex by Culicidae larvae Anopheles stephensi, Culex pipiens subsp. pipiens and Aedes aegypti was rapidly followed by a dissolution of the protein crystalline inclusions inside the anterior stomach of the three species. During the first day of intoxication, B. sphaericus spores germinated within the midgut lumen, and were in a vegetative stage between 36-48 h after ingestion when the larvae began to die. Ultrastructural observations focused on larval midgut showed alterations which differed according to the mosquito species, being localized mainly in the gastric caeca and posterior stomach. With the bacterial concentration used, neither general cell swelling nor complete breakdown of the midgut epithelium was recorded before larval death. In A. stephensi larval midgut epithelium large low-electron-density areas appeared, rough endoplasmic reticula formed numerous concentrical structures and mitochondria swelled. Large vacuoles (of unknown origin) appeared early on in the C. pipiens midgut cells, and rough endoplasmic reticula broke into small vesicles. Midgut epithelial cells of A. aegypti showed mitochondria swelling except in the anterior stomach, and a vacuolisation of smooth reticula: these aspects remained unchanged until the larvae died. PMID:3663390

  9. The Development of Narrative Productivity, Syntactic Complexity, Referential Cohesion and Event Content in Four- to Eight-Year-Old Finnish Children

    ERIC Educational Resources Information Center

    Mäkinen, Leena; Loukusa, Soile; Nieminen, Lea; Leinonen, Eeva; Kunnari, Sari

    2014-01-01

    This study focuses on the development of narrative structure and the relationship between narrative productivity and event content. A total of 172 Finnish children aged between four and eight participated. Their picture-elicited narrations were analysed for productivity, syntactic complexity, referential cohesion and event content. Each measure…

  10. Complex source mechanisms of mining-induced seismic events - implications for surface effects

    NASA Astrophysics Data System (ADS)

    Orlecka-Sikora, B.; Cesca, S.; Lasocki, S.; Rudzinski, L.; Lizurek, L.; Wiejacz, P.; Urban, P.; kozlowska, M.

    2012-04-01

    The seismicity of Legnica-Głogów Copper District (LGCD) is induced by mining activities in three mines: Lubin, Rudna and Polkowice-Sieroszowice. Ground motion caused by strong tremors might affect local infrastructure. "Żelazny Most" tailings pond, the biggest structure of this type in Europe, is here under special concern. Due to surface objects protection, Rudna Mine has been running ground motion monitoring for several years. From June 2010 to June 2011 unusually strong and extensive surface impact has been observed for 6 mining tremors induced in one of Rudna mining sections. The observed peak ground acceleration (PGA) for both horizontal and vertical component were in or even beyond 99% confidence interval for prediction. The aim of this paper is analyze the reason of such unusual ground motion. On the basis of registrations from Rudna Mine mining seismological network and records from Polish Seismological Network held by the Institute of Geophysics Polish Academy of Sciences (IGF PAN), the source mechanisms of these 6 tremors were calculated using a time domain moment tensor inversion. Furthermore, a kinematic analysis of the seismic source was performed, in order to determine the rupture planes orientations and rupture directions. These results showed that in case of the investigated tremors, point source models and shear fault mechanisms, which are most often assumed in mining seismology, are invalid. All analyzed events indicate extended sources with non-shear mechanism. The rapture planes have small dip angles and the rupture starts at the tremors hypocenter and propagates in the direction opposite to the plane dip. The tensional component plays here also big role. These source mechanisms well explain such observed strong ground motion, and calculated synthetic PGA values well correlates with observed ones. The relationship between mining tremors were also under investigation. All subsequent tremors occurred in the area of increased stress due to

  11. Transient performance

    NASA Astrophysics Data System (ADS)

    Curnock, Barry

    Gas turbine engine transient behavior, that which is concerned with the changes in engine parameters during acceleration or decceleration of an engine from one steady state point to a different steady state point, is considered. An engine can also experience cyclic aerodynamic phenomena which occur at a nominally steady condition; examples are compressor rotator stall and intake or afterburner buzz. The following are discussed: certification requirements; mechanism of acceleration; compressor working lines and surge; and some important factors (pressure level, moment of inertia, heat soakage, clearances, measurement of transients, thrust reversal, and transient maneuvers which involve significant changes to the shaft speeds of the engine). A set of graphics illustrating transient performance is presented.

  12. Complex Sedimentary and Tectonic Events Captured in Stable Sulfur Isotope Profiles from the IODP Expedition 344

    NASA Astrophysics Data System (ADS)

    Gott, C.; Riedinger, N.; Torres, M. E.; Solomon, E. A.; Bates, S. M.; Lyons, T. W.

    2014-12-01

    The impact of dynamic sedimentary and tectonic systems on biogeochemical processes, particularly the sulfur cycle, is poorly understood. To better elucidate these relationships, analyses were conducted on sediments collected during Integrated Ocean Drilling Project (IODP) Expedition 344. A primary goal of the CRISP (Costa Rica Seismogenesis Project) expedition is to explore diagenetic processes, e.g. fluid flow; relating to the complex sedimentary and tectonic environments along the Costa Rica margin. Samples collected from sites U1381C, U1413B, and U1414A record non-steady state conditions in both the solid phase and the pore water profiles, although it is most pronounced in the latter. The penetration depth of pore water sulfate at these sites varies strongly with depth between 100, 15 and several hundreds of meters, respectively. The corresponding hydrogen sulfide concentrations are >400 μM at Holes U1381C, and U1413B while they are <4 μM at Hole U1414A. The measured concentrations of iron sulfides in the sediments indicate that pyrite is the main sulfur-bearing mineral, with concentrations of 2-3 wt. % at sites U1413B and U1414A. Recorded in the sulfur isotope signal is the likely origin of the heterogeneity between sites. At Site U1414, the 34S isotopically enriched sulfate (δ34S>+60 ‰) is reflected in the δ34S profile of the in situ iron sulfides. We interpret these data as being indicative of fluid flow, potentially along fracture zones, seeps and/or pockmark features seen elsewhere in this region.

  13. Complexity of Arsenic Biogeochemistry in Surface Water Systems as Influenced by a Hydrologic Event

    NASA Astrophysics Data System (ADS)

    Markley, C. T.; Herbert, B. E.

    2006-12-01

    The arsenic cycle in oxic, surface water environments is often controlled by oxy-hydroxide minerals through sorption/desorption and precipitation/dissolution reactions. However, there are numerous instances where these minerals are found in low concentrations and/or are minimally reactive with respect to aqueous arsenic species. The presence of other anions may competitively inhibit arsenic sorption to oxy-hydroxide surfaces, thus increasing the bioavailability of arsenic and the potential toxic impacts. Microbe-mediated reactions can further impact arsenic fate and transport through accumulation and biotransformation. Arsenic biotransformation via reduction and/or methylation may result in an increased proportion of thermodynamically unfavorable arsenic species such as arsenite and methylated arsenicals in oxic surface waters. The reduced arsenic species, arsenite, is considered more mobile and toxic than the oxic species, arsenate while methylated arsenicals are often considered less toxic species. The complexity of these biogeochemical characteristics highlights the importance of studying arsenic in surface water environments. Particulate and aqueous phase metals (Fe, Mn, Al) and anions (As, P, S) were measured in surface water samples collected from the outflow creek of an arsenic-contaminated lake at high and low flow rates. Arsenic speciation, quantified via HPLC-ICP-MS, was dominated by methylated arsenicals at concentrations up to 82.7 μg/l. The common oxide-forming elements, Fe, Mn and Al were measured via ICP-AES at concentrations up to 2.4 mg/l, 0.88 mg/l and 3.3 mg/l, respectively. However, arsenic was not associated with the particulate phase mineralogy, being approximately 100% in the aqueous (< 0.2 μm ) phase, indicating high arsenic bioavailability. High alkalinity, phosphorous and sulfur concentrations up to 516 mgHCO3/meq, 2.0mg/l and 50 mg/l, respectively, likely out-competed arsenic for sorption to these oxide mineral surfaces. Geochemical

  14. Interaction of Strong Transient Interplanetary Disturbances with the Dayside Magnetosphere

    NASA Technical Reports Server (NTRS)

    Berchem, Jean

    2004-01-01

    The objective of the investigation was to gain an understanding of the complex response of the magnetosphere to strong transient interplanetary disturbances. Because the project was only funded for a year, the investigation focused on only one of the three topics proposed in the original three year proposal. We investigated the response of the dayside auroral region to strong transient interplanetary disturbances. The method of the investigation was to use three-dimensional magnetohydrodynamic (MHD) simulations that employ measurements of the solar wind conditions upstream the bow shock to model actual events and then to compare the simulation results with observations from spacecraft located at downstream locations. We modeled an event that occurred on July 14,2000, for which both CLUSTER and IMAGE simultaneous observations were available. The event was marked by high solar wind dynamic pressure and a strong IMF By component. Comparisons showed a very good agreement between intensifications in the auroral emissions measured by IMAGE

  15. Very High Resolution Numerical Weather Prediction of Wind Shear Event in the Complex Terrain Around Juneau Alaska

    NASA Astrophysics Data System (ADS)

    Morton, D.; Arnold, D.; Schicker, I.; Dierking, C.; Harrison, K.

    2011-12-01

    Juneau International Airport is surrounded by complex terrain, often presenting challenging conditions to departing aircraft. General aviation departure procedures for Runway 08 include a 180-degree right turn "as soon as practical" in order to avoid steeply rising terrain. Under strong wind conditions characterized by post-frontal topographically enhanced wind shear, aircraft following these procedures may encounter turbulence or wind shear classified as severe. In January 1993, a Boeing 727 aircraft at a 30-degree bank encountered extreme crosswinds resulting in departure from controlled flight, with successful recovery occurring within only 50 meters of the ground. In this work, we focus on a similar event at Juneau from December 2009. This case has been modeled with WRF at very high resolutions down to 111 m horizontal, with mixed results. The focus of this work is to investigate in more detail the problems, costs and benefits of using very high resolution topography and model runs in a high-wind event in complex terrain. Several model runs will be performed, and results will be compared with each other and station observations available through the Juneau Airport Wind System (JAWS). Two high resolution topographies - the USGS National Elevation Dataset (NED) and the Shuttle Radar Topography Mission (SRTM) - will be compared with the USGS 30s topography in their ability to match the real topography and their influence on forecast winds. Additionally, an attempt will be made to push the model into the realm of Large Eddy Simulation (LES) with a 50 m horizontal resolution in a limited region.

  16. Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igneous Complex, South Africa

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; Vakkari, V.; Tiitta, P.; Manninen, H. E.; Gagné, S.; Laakso, H.; Kulmala, M.; Mirme, A.; Mirme, S.; Mabaso, D.; Beukes, J. P.; Laakso, L.

    2012-05-01

    South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring and being processed in a large geological structure termed the Bushveld Igneous Complex (BIC). The area is also highly populated by informal, semi-formal and formal residential developments. However, knowledge of air quality and research related to the atmosphere is still very limited in the area. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distributions and number concentrations, together with meteorological parameters, trace gases and particulate matter (PM) were measured for over two years at Marikana in the heart of the western BIC. The observations showed that trace gas (i.e. SO2, NOx, CO) and black carbon concentrations were relatively high, but in general within the limits of local air quality standards. The area was characterised by very high condensation sink due to background aerosol particles, PM10 and O3 concentration. The results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO2-based nucleation followed by the growth by condensation of vapours from industrial, residential and natural sources was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. The air mass back trajectory and wind direction analyses showed that the secondary particle formation was influenced both by local and regional pollution and vapour sources. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during nucleation events were similar to results previously published for a semi

  17. Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igeneous Complex, South Africa

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; Vakkari, V.; Tiitta, P.; Manninen, H. E.; Gagné, S.; Laakso, H.; Kulmala, M.; Mirme, A.; Mirme, S.; Mabaso, D.; Beukes, J. P.; Laakso, L.

    2012-01-01

    South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring in a large geological structure termed the Bushveld Igeneous Complex (BIC). The majority of the world's platinum group metals (PGMs) and chromium originate from the BIC. Considering the importance of PGMs in the manufacturing of automotive catalytic converters, as well as the relatively poor current state of air quality and the general lack of atmospheric research in the BIC, atmospheric related research in this geographical area is of local (South African) and of international interest. The western limb of the BIC is the most exploited, with at least eleven pyrometallurgical smelters occurring within a 55 km radius. Due to the lure of employment in the industrialised BIC, the area is populated by informal, semi-formal and formal residential developments. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distribution and concentration measurements were conducted for over two years at Marikana in the heart of the western BIC. Our results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO2-based nucleation (from industrial emissions) was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. Secondary particle formation was influenced both by local pollution sources and regional ambient conditions. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during nucleation events were similar to the results from a semi-clean savannah site in South Africa.

  18. Complex network analysis of high rainfall events during the northeast monsoon over south peninsular India and Sri Lanka

    NASA Astrophysics Data System (ADS)

    Martin, P.; Malik, N.; Marwan, N.; Kurths, J.

    2012-04-01

    The Indian Summer monsoon (ISM) accounts for a large part of the annual rainfall budget across most of the Indian peninsula; however, the coastal regions along the southeast Indian peninsula, as well as Sri Lanka, receive 50% or more of their annual rainfall budget during the northeast monsoon (NEM), or winter monsoon, during the months from October through December. In this study, we investigate the behavior of the NEM over the last 60 years using complex network theory. The network is constructed according to a method previously developed for the ISM, using event synchronization of extreme rainfall events as a correlation measure to create directed and undirected links between geographical locations, which represent potential pathways of moisture transport. Network measures, such as degree centrality and closeness centrality, are then used to illuminate the dynamics of the NEM rainfall over the relevant regions, and to examine the spatial distribution and temporal evolution of the rainfall. Understanding the circulation of the monsoon cycle as a whole, i.e. the NEM together with the ISM, is vital for the agricultural industry and thus the population of the affected areas.

  19. SOLA-PTS: a transient, three-dimensional algorithm for fluid-thermal mixing and wall heat transfer in complex geometries

    SciTech Connect

    Daly, B.J.; Torrey, M.D.

    1984-07-01

    The SOLA-PTS computer code has been developed to analyze fluid-thermal mixing in the cold legs and downcomer of pressurized water reactors in support of the pressurized thermal shock study. SOLA-PTS is a transient, three-dimensional code with the capability of resolving complex geometries using variable cell noding in the three coordinate directions. The computational procedure is second-order accurate and utilizes a state-of-the-art iteration method that allows rapid convergence to an accurate solution for the pressure field. Two different turbulence models are used in the code, a two-equation k-epsilon model that is used in the cold leg pipe away from the HPI inlet and a three-equation k-epsilon-T'/sup 2/ model for use near the HPI inlet and in the downcomer. The physical modeling and the numerical procedure used in SOLA-PTS are described in this report. Applications of the method to two Creare 1/5th-scale experiments are also presented. Two appendices are included which provides a comparison of the two- and three-equation turbulence models, and instructions for setting up and running a problem with SOLA-PTS.

  20. Evolutionary site-number changes of ribosomal DNA loci during speciation: complex scenarios of ancestral and more recent polyploid events

    PubMed Central

    Rosato, Marcela; Moreno-Saiz, Juan C.; Galián, José A.; Rosselló, Josep A.

    2015-01-01

    Several genome duplications have been identified in the evolution of seed plants, providing unique systems for studying karyological processes promoting diversification and speciation. Knowledge about the number of ribosomal DNA (rDNA) loci, together with their chromosomal distribution and structure, provides clues about organismal and molecular evolution at various phylogenetic levels. In this work, we aim to elucidate the evolutionary dynamics of karyological and rDNA site-number variation in all known taxa of subtribe Vellinae, showing a complex scenario of ancestral and more recent polyploid events. Specifically, we aim to infer the ancestral chromosome numbers and patterns of chromosome number variation, assess patterns of variation of both 45S and 5S rDNA families, trends in site-number change of rDNA loci within homoploid and polyploid series, and reconstruct the evolutionary history of rDNA site number using a phylogenetic hypothesis as a framework. The best-fitting model of chromosome number evolution with a high likelihood score suggests that the Vellinae core showing x = 17 chromosomes arose by duplication events from a recent x = 8 ancestor. Our survey suggests more complex patterns of polyploid evolution than previously noted for Vellinae. High polyploidization events (6x, 8x) arose independently in the basal clade Vella castrilensis–V. lucentina, where extant diploid species are unknown. Reconstruction of ancestral rDNA states in Vellinae supports the inference that the ancestral number of loci in the subtribe was two for each multigene family, suggesting that an overall tendency towards a net loss of 5S rDNA loci occurred during the splitting of Vellinae ancestors from the remaining Brassiceae lineages. A contrasting pattern for rDNA site change in both paleopolyploid and neopolyploid species was linked to diversification of Vellinae lineages. This suggests dynamic and independent changes in rDNA site number during speciation processes and a

  1. Proliferative events experimentally induced by a transient cold shock in the brain of adult terrestrial heterothermic vertebrates: preliminary analysis of PCNA expression in Podarcis sicula.

    PubMed

    Margotta, Vito

    2014-01-01

    In past studies on the encephalic regenerative phenomena some authors adopted a pre-surgi- cal stratagem (drastic, sudden, transient thermal stimulus) to adult brain-injured newts to limit death rate upon surgery and with this method, unexpected tissue reparation was obtained. This procedure became a routine technicality also in frog and lizard to stimulate an increase in the neurogenesis, attributable to putative stem cells which appear either in clusters ("matrix areas" or "matrix zones"), mostly at or near the telencephalic ventricular surfaces, or scattered ("matrix cells") within other cerebral districts. On the basis of this literature background, planning an immunocytochemical re-evaluation of the survival of latent proliferative properties in these adult cold shocked organisms, as already studied in Triturus carnifex, the actual investigation was carried out on the brain of Podarcis sicula not subjected to cerebral injury. The immunohistochem- ical expression of the proliferating cell nuclear antigen (PCNA) seemed moderate only in those encephalic portions better provided with cells in stand-by: the olfactory peduncles and the telen- cephalic zonae germinativae ventrales. This scenario appeared rather disappointed and inadequate with respect to the unexpected, widespread restoration of the removed portions observed by previous authors. These findings could be due both to a small effectiveness of a relatively mild thermal stress, depending on the difference between the applied temperature and seasonal one, to the lack of other experimental conditions (surgical trauma, encephalic injury) adopted in the past, and to the interspecific differences in sensitivity, since lacertilian Reptiles are less endowed with proliferative/regenerative power than Amphibians, mainly Urodela, and Teleosts. PMID:25665278

  2. Assessing the Influence of an Individual Event in Complex Fault Spreading Network Based on Dynamic Uncertain Causality Graph.

    PubMed

    Dong, Chunling; Zhao, Yue; Zhang, Qin

    2016-08-01

    Identifying the pivotal causes and highly influential spreaders in fault propagation processes is crucial for improving the maintenance decision making for complex systems under abnormal and emergency situations. A dynamic uncertain causality graph-based method is introduced in this paper to explicitly model the uncertain causalities among system components, identify fault conditions, locate the fault origins, and predict the spreading tendency by means of probabilistic reasoning. A new algorithm is proposed to assess the impacts of an individual event by investigating the corresponding node's time-variant betweenness centrality and the strength of global causal influence in the fault propagation network. The algorithm does not depend on the whole original and static network but on the real-time spreading behaviors and dynamics, which makes the algorithm to be specifically targeted and more efficient. Experiments on both simulated networks and real-world systems demonstrate the accuracy, effectiveness, and comprehensibility of the proposed method for the fault management of power grids and other complex networked systems. PMID:27101619

  3. Transient Observations with LSST

    NASA Astrophysics Data System (ADS)

    Walkowicz, Lucianne

    2010-12-01

    In the coming decade, LSST';s combination of all-sky coverage, consistent long-term monitoring, and flexible criteria for event identification will revolutionize studies of a wide variety of astrophysical phenomena. The umbrella of time domain science with LSST encompasses objects both familiar and exotic, from classical variables within our Galaxy to explosive cosmological events. LSST will make localization for gravity wave events possible, identify counterparts to GRBs and X-ray flashes, and discover new supernovae. Increased sample sizes of known-but-rare observational phenomena will quantify their distributions for the first time, thus challenging existing theory. Perhaps most excitingly, LSST will provide the opportunity to sample previously untouched regions of parameter space, where transient events are expected on theoretical grounds, but have not yet been observed. LSST will generate "alerts" within 60 seconds of detecting a new transient, permitting the community t o follow up unusual events in greater detail. Here, I highlight some of the scientific opportunities LSST will provide, as well as the challenges we face and opportunities for community involvement.

  4. Scanning mass spectrometry probe: a scanning probe electrospray ion source for imaging mass spectrometry of submerged interfaces and transient events in solution.

    PubMed

    Kottke, Peter A; Degertekin, F Levent; Fedorov, Andrei G

    2010-01-01

    The scanning mass spectrometry (SMS) probe is a new electrospray ion source. Motivated by the need for untargeted chemical imaging of dynamic events in solution, we have exploited an approach to electrospray ionization (ESI) that allows continuous sampling from a highly localized volume (approximately picoliters) in a liquid environment, softly ionizes molecules in the sample to render them amenable for mass spectrometric analysis, and sends the ions to the mass spectrometer. The key underlying concepts for our approach are (1) treating the electrospray capillary inlet as a chemical scanning probe and (2) locating the electrospray point as close as possible to the sampling point, thus providing the shortest response time possible. This approach enables chemical monitoring or imaging of submerged interfaces, providing access to details of spatial heterogeneity and temporal changes within liquid samples. It also permits direct access to liquid/ liquid interfaces for ESI-MS analysis. In this letter we report the first demonstrations of these capabilities of the SMS probe and describe some of the probe's basic characteristics. PMID:19904914

  5. Transient receptor potential canonical 3 (TRPC3) is required for IgG immune complex-induced excitation of the rat dorsal root ganglion neurons

    PubMed Central

    Qu, Lintao; Li, Yumei; Pan, Xinghua; Zhang, Pu; LaMotte, Robert H.; Ma, Chao

    2012-01-01

    Chronic pain may accompany immune-related disorders with an elevated level of serum IgG immune complex (IgG-IC) but the underlying mechanisms are obscure. We previously demonstrated that IgG-IC directly excited a subpopulation of dorsal root ganglion (DRG) neurons through the neuronal Fc-gamma receptor I (FcγRI). This might be a mechanism linking IgG-IC to pain and hyperalgesia. The purpose of this study was to investigate the signaling pathways and transduction channels activated downstream of IgG-IC and FcγRI. In whole-cell recordings, IgG-IC induced a non-selective cation current (IIC) in the rat DRG neurons, carried by Ca2+ and Na+. The IIC was potentiated or attenuated by respectively lowering or increasing the intracellular Ca2+ buffering capacity, suggesting that this current was regulated by intracellular calcium. Single-cell RT-PCR revealed that transient receptor potential canonical 3 (TRPC3) mRNA was always coexpressed with FcγRI mRNA in the same DRG neuron. Moreover, ruthenium red (a general TRP channel blocker), BTP2 (a general TRPC channel inhibitor) or pyrazole-3 (a selective TRPC3 blocker), each potently inhibited the IIC. Specific knockdown of TRPC3 using small interfering RNA attenuated the IgG-IC-induced Ca2+ response and the IIC. Additionally, the IIC was blocked by the tyrosine kinase Syk inhibitor OXSI-2, the phospholipase C (PLC) inhibitor neomycin, or either the IP3 receptor antagonist 2-aminoethyldiphenylborinate or heparin. These results indicated that the activation of neuronal FcγRI triggers TRPC channels through the Syk-PLC-IP3 pathway, and that TRPC3 is a key molecular target for the excitatory effect of IgG-IC on DRG neurons. PMID:22787041

  6. Peach Bottom Transients Analysis with TRAC/BF1-VALKIN

    SciTech Connect

    Verdu, G.; Miro, R.; Sanchez, A.M.; Rosello, O.; Ginestar, D.; Vidal, V.

    2004-10-15

    The TRAC/BF1-VALKIN code is a new time domain analysis code for studying transients in a boiling water reactor. This code uses the best-estimate code TRAC/BF1 to give an account of the heat transfer and thermal-hydraulic processes and a three-dimensional neutronics module. This module has two options: the MODKIN option that makes use of a modal method based on the assumption that the neutronic flux can be approximately expanded in terms of the dominant lambda modes associated with a static configuration of the reactor core, and the NOKIN option that uses a one-step backward discretization of the neutron diffusion equation. To check the performance of the TRAC/BF1-VALKIN code, the Peach Bottom turbine trip transient has been simulated, because this transient is a dynamically complex event where neutron kinetics is coupled with thermal hydraulics in the reactor primary system, and reactor variables change very rapidly.

  7. Using Complex Event Processing (CEP) and vocal synthesis techniques to improve comprehension of sonified human-centric data

    NASA Astrophysics Data System (ADS)

    Rimland, Jeff; Ballora, Mark

    2014-05-01

    The field of sonification, which uses auditory presentation of data to replace or augment visualization techniques, is gaining popularity and acceptance for analysis of "big data" and for assisting analysts who are unable to utilize traditional visual approaches due to either: 1) visual overload caused by existing displays; 2) concurrent need to perform critical visually intensive tasks (e.g. operating a vehicle or performing a medical procedure); or 3) visual impairment due to either temporary environmental factors (e.g. dense smoke) or biological causes. Sonification tools typically map data values to sound attributes such as pitch, volume, and localization to enable them to be interpreted via human listening. In more complex problems, the challenge is in creating multi-dimensional sonifications that are both compelling and listenable, and that have enough discrete features that can be modulated in ways that allow meaningful discrimination by a listener. We propose a solution to this problem that incorporates Complex Event Processing (CEP) with speech synthesis. Some of the more promising sonifications to date use speech synthesis, which is an "instrument" that is amenable to extended listening, and can also provide a great deal of subtle nuance. These vocal nuances, which can represent a nearly limitless number of expressive meanings (via a combination of pitch, inflection, volume, and other acoustic factors), are the basis of our daily communications, and thus have the potential to engage the innate human understanding of these sounds. Additionally, recent advances in CEP have facilitated the extraction of multi-level hierarchies of information, which is necessary to bridge the gap between raw data and this type of vocal synthesis. We therefore propose that CEP-enabled sonifications based on the sound of human utterances could be considered the next logical step in human-centric "big data" compression and transmission.

  8. Gaia transient detection efficiency: hunting for nuclear transients

    NASA Astrophysics Data System (ADS)

    Blagorodnova, N.; Van Velzen, S.; Harrison, D. L.; Koposov, S.; Mattila, S.; Campbell, H.; Walton, N. A.; Wyrzykowski, Ł.

    2016-01-01

    We present a study of the detectability of transient events associated with galaxies for the Gaia European Space Agency astrometric mission. We simulated the on-board detections, and on-ground processing for a mock galaxy catalogue to establish the properties required for the discovery of transient events by Gaia, specifically tidal disruption events (TDEs) and supernovae (SNe). Transients may either be discovered by the on-board detection of a new source or by the brightening of a previously known source. We show that Gaia transients can be identified as new detections on-board for offsets from the host galaxy nucleus of 0.1-0.5 arcsec, depending on magnitude and scanning angle. The Gaia detection system shows no significant loss of SNe at close radial distances to the nucleus. We used the detection efficiencies to predict the number of transients events discovered by Gaia. For a limiting magnitude of 19, we expect around 1300 SNe per year: 65 per cent SN Ia, 28 per cent SN II and 7 per cent SN Ibc, and ˜20 TDEs per year.

  9. Early folding events during light harvesting complex II assembly in vitro monitored by pulsed electron paramagnetic resonance.

    PubMed

    Fehr, Niklas; García-Rubio, Inés; Jeschke, Gunnar; Paulsen, Harald

    2016-06-01

    Efficient energy transfer in the major light harvesting complex II (LHCII) of green plants is facilitated by the precise alignment of pigments due to the protein matrix they are bound to. Much is known about the import of the LHCII apoprotein into the chloroplast via the TOC/TIC system and its targeting to the thylakoid membrane but information is sparse about when and where the pigments are bound and how this is coordinated with protein folding. In vitro, the LHCII apoprotein spontaneously folds and binds its pigments if the detergent-solubilized protein is combined with a mixture of chlorophylls a and b and carotenoids. In the present work, we employed this approach to study apoprotein folding and pigment binding in a time-resolved manner by using pulsed electron paramagnetic resonance (EPR). Intra-molecular distances were measured before folding, after 255 ms and 40 s folding time in the absence of cryoprotectant, and in the fully folded and assembled LHCII. In accordance with earlier results, the most of the folding of the three membrane-spanning alpha helices precedes their apposition into the final tertiary structure. However, their formation follows different kinetics, partially extending into the final phase of LHCII formation during which much of the condensation of the pigment-protein structure occurs, presumably governed by the binding of chlorophyll b. A rough timetable is proposed to sort partial events into the LHCII formation process. PMID:27063475

  10. Heater drain system transient monitoring

    SciTech Connect

    Voll, B.J.; Farsaci, C.D.

    1995-12-01

    Feedwater heater drain systems are susceptible to unstable, two phase flow conditions. These instabilities are difficult to predict and are dependent on plant-specific system designs and operating conditions. Therefore, significant vibrations and transient events can occur that the systems are not specifically designed for. This paper describes how heater drain system responses due to unanticipated transient events at a nuclear plant were captured and quantified using a digital data acquisition system. The setup of the data acquisition system, including the determination of what parameters to monitor and how to effectively capture potential transient events, is discussed. This paper also discusses the monitoring results and their relevance to system modification evaluations and root cause evaluations.

  11. ON DETECTING TRANSIENT PHENOMENA

    SciTech Connect

    Belanger, G.

    2013-08-10

    Transient phenomena are interesting and potentially highly revealing of details about the processes under observation and study that could otherwise go unnoticed. It is therefore important to maximize the sensitivity of the method used to identify such events. In this article, we present a general procedure based on the use of the likelihood function for identifying transients which is particularly suited for real-time applications because it requires no grouping or pre-processing of the data. The method makes use of all the information that is available in the data throughout the statistical decision-making process, and is suitable for a wide range of applications. Here we consider those most common in astrophysics, which involve searching for transient sources, events or features in images, time series, energy spectra, and power spectra, and demonstrate the use of the method in the case of a weak X-ray flare in a time series and a short-lived quasi-periodic oscillation in a power spectrum. We derive a fit statistic that is ideal for fitting arbitrarily shaped models to a power density distribution, which is of general interest in all applications involving periodogram analysis.

  12. Searching for Low-Frequency Radio Transients from Supernovae

    NASA Astrophysics Data System (ADS)

    Tsai-Wei, Jr.; Cutchin, Sean; Kothari, Manthan; Schmitt, Christian; Kavic, Michael; Simonetti, John

    2011-10-01

    Supernovae events may be accompanied by prompt emission of a low-frequency electromagnetic transient. These transient events are created by the interaction of a shock wave of charged particles created by SN core-collapse with a stars ambient magnetic field. Such events can be detected in low-frequency radio array. Here we discuss an ongoing search for such events using two radio arrays: the Long Wavelength Array (LWA) and Eight-meter-wavelength Transient Array (ETA).

  13. Reactor System Transient Code.

    Energy Science and Technology Software Center (ESTSC)

    1999-07-14

    RELAP3B describes the behavior of water-cooled nuclear reactors during postulated accidents or power transients, such as large reactivity excursions, coolant losses or pump failures. The program calculates flows, mass and energy inventories, pressures, temperatures, and steam qualities along with variables associated with reactor power, reactor heat transfer, or control systems. Its versatility allows one to describe simple hydraulic systems as well as complex reactor systems.

  14. The VAO Transient Facility

    NASA Astrophysics Data System (ADS)

    Graham, Matthew J.; Djorgovski, S. G.; Drake, Andrew; Mahabal, Ashish; Williams, Roy; Seaman, Rob

    2012-04-01

    The time-domain community wants robust and reliable tools to enable the production of, and subscription to, community-endorsed event notification packets (VOEvent). The Virtual Astronomical Observatory (VAO) Transient Facility (VTF) is being designed to be the premier brokering service for the community, both collecting and disseminating observations about time-critical astronomical transients but also supporting annotations and the application of intelligent machine-learning to those observations. Two types of activity associated with the facility can therefore be distinguished: core infrastructure, and user services. We review the prior art in both areas, and describe the planned capabilities of the VTF. In particular, we focus on scalability and quality-of-service issues required by the next generation of sky surveys such as LSST and SKA.

  15. Initiation of a coronal transient

    SciTech Connect

    Low, B.C.; Munro, R.H.; Fisher, R.R.

    1982-03-01

    This paper analyzes the coronal transient/eruptive prominence event of 1980 August 5 observed by the Mauna Loa experiment system. This event yielded data on the early development of the transient in the low corona between 1.2 R/sub sun/ and 2.2 R/sub sun/, information which was not available when earlier attempts were made to explain transient phenomena. The transient's initial appearance in the form of a rising density-depleted structure, prior to the eruption of the associated prominence, can be explained as an effect of magnetic buoyancy. The data indicate that this transient has a density depletion of 17% to 33% relative to an undisturbed corona which is approximately isothermal with a temperature of 1.5 x 10/sup 6/ K and a coronal density of 1.0 x 10/sup 9/ cm/sup -3/ at the base of the corona. The height versus base length relationship of the evolving transient resembles, remarkably well, the theoretical predictions obtained from a quasi-static model of a margnetically buoyant loop system. By matching this relationship with the theoretical model, we estimate the magnetic field at the base of the transient to be between 2 and 3 gauss. It is also shown that the initial, nearly constant speed of the top of the transient, 80 +- 20 km s/sup -1/, is consistent with a theoretical estimate calculated from the quasi-static model. These results suggest that some transients are not initiated impulsively, the initial stage of the development being driven by a quasi-static response to a slow change in magnetic field conditions at the base of the corona.

  16. A Multiple-Channel Sub-Band Transient Detection System

    SciTech Connect

    David A. Smith

    1998-11-01

    We have developed a unique multiple-channel sub-band transient detection system to record transient electromagnetic signals in carrier-dominated radio environments; the system has been used to make unique observations of weak, transient HF signals. The detection system has made these observations possible through improved sensitivity compared to conventional broadband transient detection systems; the sensitivity improvement is estimated to be at least 20 dB. The increase in sensitivity has been achieved through subdivision of the band of interest (an 18 MHz tunable bandwidth) into eight sub-band independent detection channels, each with a 400 kHz bandwidth and its own criteria. The system generates a system trigger signal when a predetermined number of channels (typically five) trigger within a predetermined window of time (typically 100 ~s). Events are recorded with a broadband data acquisition system sampling at 50 or 100 Msample/s, so despite the fact that the detection system operates on portions of the signal confined to narrow bands, data acquisition is broadband. Between May and September of 1994, the system was used to detect and record over six thousand transient events in the frequency band from 3 to 30 MHz. Approximately 500 of the events have been characterized as paired bursts of radio noise with individual durations of 2 to 10 ps and separations between the bursts of 5 to 160 ps. The paired transients are typically 5 to 40 dB brighter than the background electromagnetic spectrum between carrier signals. We have termed these events SubIonospheric Pulse Pairs (SIPPS) and presently have no explanation as to their source. Our observations of SIPPS resemble observations of TransIonospheric Pulse Pairs (TIPPs) recorded by the Blackboard instrument on the ALEXIS satellite; the source of TIPP events is also unknown. Most of the recorded SIPP events do not exhibit frequency dispersion, implying propagation along a line-of-sight (groundwave) path; but seven of

  17. Ultrafast transient absorption studies of environment influence on the photolysis of B12 complexes and the subsequent recombination and escape of caged radicals

    NASA Astrophysics Data System (ADS)

    Stickrath, Andrew B.

    Femtosecond to nanosecond transient absorption experiments were performed on a series of B12 complexes to assess the influence of the solvent environment on the excited state electronic structure and resulting dynamics. A series of alkylcobalamins (adenosyl-, ethyl, methyl, and propylcobalamin), all of which are known to undergo cobalt-carbon bond homolysis in response to excitation at 400nm were studied in a variety of surroundings. Measurements on adenosylcobalamin (coenzyme B12) bound to glutamate mutase demonstrate a metal-to-ligand-charge-transfer (MLCT) state en route to bond homolysis, supported by protein influence on the excited state electronic structure. This charge transfer intermediate, which is similar to that reported in the literature for methylcobalamin, is not observed for free adenosylcobalamin. Measurements on methylcobalamin probe solvent influence on the MLCT state and characterize it by a large charge density transfer. This result is in contrast to studies on cyanocobalamin, which is not observed to undergo homolysis, where the solvent dependent lifetime of an intermediate ligand-to-metal-charge-transfer (LMCT) state is characterized by a modest transfer of charge density. Such a LMCT intermediate is observed for adenosylcobalamin in water leading to bond homolysis. The protein has greatly altered the photochemical pathway to homolysis, which is expected to be representative of influence on thermolysis. Upon homolysis the photoinduced alkyl and cob(II)alamin radicals may recombine or escape the solvent cage to form solvent separated radical pairs which do not recombine in the bulk by the 9ns time limit of these experiments. Recombination can be monitored directly via the oxidation state of the cobalt atom. The neutral alkyl radical is a paradigm for small particle escape and diffusive motion in a liquid. The escape behavior is similar for adenosyl, ethyl, and propyl radicals indicating that hydrogen bonding with the solvent is not a major

  18. (Nitro)Iron(III) Porphyrins. EPR Detection of a Transient Low-Spin Iron(III) Complex and Structural Characterization of an O Atom Transfer Product.

    PubMed

    Munro, Orde Q.; Scheidt, W. Robert

    1998-05-01

    The reaction of BF(3).OEt(2) with the bis(nitro) complex of iron(III) picket-fence porphyrin, [K(18C6)(OH(2))][Fe(TpivPP)(NO(2))(2)], leads to the formation of a transient porphyrin intermediate, assigned on the basis of its rhombic low-spin EPR spectrum as the five-coordinate N-bound mono(nitro) iron(III) derivative, [Fe(TpivPP)(NO(2))]. This species is reactive and readily undergoes oxygen atom transfer to form [Fe(III)(TpivPP)(NO(3))] and [Fe(II)(TpivPP)(NO)]. The reactions have been followed by EPR and IR spectroscopy. [Fe(TpivPP)(NO(2))] has a rhombic EPR spectrum (g = 2.60, 2.35, and 1.75) in chlorobenzene and CH(2)Cl(2) and is spectroscopically distinct from the bis(nitro) starting material (g = 2.70, 2.50, and 1.57). Oxidation of the nitrosyl species to [Fe(TpivPP)(NO(3))] proceeds via an intermediate assigned as [Fe(TpivPP)(NO(2))] on the basis of its EPR spectrum. The crystal structure of one of the reaction products, [Fe(TpivPP)(NO(3))], has been determined. The nitrate ion of [Fe(TpivPP)(NO(3))] is bound to the iron(III) ion in a "symmetric" bidentate fashion within the ligand-binding pocket of the porphyrin pickets. Individual Fe-O distances are 2.123(3) and 2.226(3) Å. The dihedral angle between the plane of the nitrate ion and the closest N(p)-Fe-N(p) plane is 10.0 degrees. The Fe-N(p) bonds (and trans N(p)-Fe-N(p) angles) perpendicular and parallel to the plane of the axial ligand average to 2.060(5) Å (154.84(9) degrees ) and 2.083(3) Å (146.14(9) degrees ), respectively. Crystal data for [Fe(TpivPP)(NO(3))]: a = 23.530(2) Å, b = 10.0822(5) Å, c = 48.748(3) Å, beta = 92.145(5) degrees, monoclinic, space group I2/a, V = 11556.4(14) Å(3), Z = 8, FeN(9)O(7)C(64)H(64), 8798 observed data, R(1) = 0.0606, wR(2) = 0.1313, all observations at 127(2) K. PMID:11670389

  19. The transient pore formed by homologous terminal complement complexes functions as a bidirectional route for the transport of autocrine and paracrine signals across human cell membranes.

    PubMed Central

    Acosta, J. A.; Benzaquen, L. R.; Goldstein, D. J.; Tosteson, M. T.; Halperin, J. A.

    1996-01-01

    BACKGROUND: We have previously shown that the membrane attack complex (MAC) of complement stimulates cell proliferation and that insertion of homologous MAC into the membranes of endothelial cells results in the release of potent mitogens, including basic fibroblast growth factor (bFGF). The mechanism of secretion of bFGF and other polypeptides devoid of signal peptides, such as interleukin 1 (IL-1) is still an open problem in cell biology. We have hypothesized that the homologous MAC pore itself could constitute a transient route for the diffusion of biologically active macromolecules in and out of the target cells. MATERIALS AND METHODS: Human red blood cell ghosts and artificial lipid vesicles were loaded with labeled growth factors, cytokines and IgG, and exposed to homologous MAC. The release of the 125I-macromolecules was followed as a function of time. The incorporation of labeled polypeptides and fluorescent dextran (MW: 10,000) was measured in MAC-impacted human red blood cells and human umbilical endothelial cells (HUVEC), respectively. RESULTS: Homologous MAC insertion into HUVEC resulted in the massive uptake of 10-kD dextran and induced the release of bFGF, in the absence of any measurable lysis. Red blood cell ghosts preloaded with bFGF, IL-1 beta, and the alpha-chain of interferon-gamma (IFN-gamma) released the polypeptides upon MAC insertion, but they did not release preloaded IgG. MAC-impacted ghosts took up radioactive IFN-gamma from the extracellular medium. Vesicles loaded with IL-I released the polypeptide when exposed to MAC. CONCLUSIONS: The homologous MAC pore in its nonlytic form allows for the export of cytosolic proteins devoid of signal peptides that are not secreted through the classical endoplasmic reticulum/Golgi exocytotic pathways. Our results suggest that the release, and perhaps the uptake, of biologically active macromolecules through the homologous MAC pore is a novel biological function of the complement system in mammals

  20. Leadership within Emergent Events in Complex Systems: Micro-Enactments and the Mechanisms of Organisational Learning and Change

    ERIC Educational Resources Information Center

    Hazy, James K.; Silberstang, Joyce

    2009-01-01

    One tradition within the complexity paradigm considers organisations as complex adaptive systems in which autonomous individuals interact, often in complex ways with difficult to predict, non-linear outcomes. Building upon this tradition, and more specifically following the complex systems leadership theory approach, we describe the ways in which…

  1. Studies of Transient Meteor Activity

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter M. M.

    2002-01-01

    Meteoroids bombard Earth's atmosphere daily, but occasionally meteor rates increase to unusual high levels when Earth crosses the relatively fresh ejecta of comets. These transient events in meteor activity provide clues about the whereabouts of Earth-threatening long-period comets, the mechanisms of large-grain dust ejection from comets, and the particle composition and size distribution of the cometary ejecta. Observations of these transient events provide important insight in natural processes that determine the large grain dust environment of comets, in natural phenomena that were prevalent during the time of the origin of life, and in processes that determine the hazard of civilizations to large impacts and of man-made satellites to the periodic blizzard of small meteoroids. In this proposal, three tasks form a coherent program aimed at elucidating various aspects of meteor outbursts, with special reference to planetary astronomy and astrobiology. Task 1 was a ground-based effort to observe periods of transient meteor activity. This includes: (1) stereoscopic imaging of meteors during transient meteor events for measurements of particle size distribution, meteoroid orbital dispersions and fluxes; and (2) technical support for Global-MS-Net, a network of amateur-operated automatic counting stations for meteor reflections from commercial VHF radio and TV broadcasting stations, keeping a 24h vigil on the level of meteor activity for the detection of new meteor streams. Task 2 consisted of ground-based and satellite born spectroscopic observations of meteors and meteor trains during transient meteor events for measurements of elemental composition, the presence of organic matter in the meteoroids, and products generated by the interaction of the meteoroid with the atmosphere. Task 3 was an airborne effort to explore the 2000 Leonid meteor outbursts, which are anticipated to be the most significant of transient meteor activity events in the remainder of the

  2. Quarterly progress report for Q2 FY06 for Complex Transient Events in Materials Studied Using Ultrafast Electron Probes and Terascale Simulation (FWP SCW0289)

    SciTech Connect

    Campbell, G H

    2006-03-29

    In this quarter (Q2 FY06), the DTEM underwent a substantial reconfiguration of its laser systems. The cathode laser system was changed to provide greater numbers of electrons per pulse by lengthening the time duration of the pulse to 30 ns. The greater number of electrons per pulse has allowed us to acquire high quality pulsed images and diffraction patterns. The spatial resolution in the single pulsed image has been measured at better than 20 nm. The diffraction patterns are now more comparable to conventional electron microscope operation. Examples are found in the body of the report. We summarize important achievements in the following list: (1) Instrument performance and design improvements--(A) The laser system was changed for the cathode photoemission system (75 ns at 1053 nm wavelength converted to 30ns at 211 nm wavelength) to give longer electron pulses at the same current to yield more electrons per pulse. (B) New specimen drive laser constructed. (C) New computer monitored and controlled alignment systems installed for both laser systems to facilitate laser alignment through a user friendly computer interface. (2) Experimental Progress--(A) The spatial resolution of pulsed images was tested by imaging a cross-section of multilayer thin foils with 30 nm and 20 nm periods. Single pulse images were observed to have spatial resolution better than 20 nm. This combination of 20 nm spatial and 30 ns temporal resolution is thought to be highest combined spatial and temporal measurement ever made. (B) The quality of single pulse electron diffraction patterns have been improved to the point where differentiating the HCP from BCC patterns in Ti is substantially easier. The spatial coherence of the electron illumination on the specimen was improved to give much smaller diffraction spots in the pattern.

  3. A transient auroral event on the dayside

    NASA Technical Reports Server (NTRS)

    Heikkila, Walter J.; Jorgensen, T. Stockflet T.; Lanzerotti, Louis J.; Maclennan, Carol G.

    1989-01-01

    A strong perturbation lasting about 10 min, beginning at 0930 UT on December 5, 1986, was recorded by high-latitude magnetometer stations in Greenland, Iqaluit, and the South Pole. Viking and Polar Bear satellite observations of the perturbation and observations of similar perturbations on the afternoon side in Svalbard, Heiss Island, and northern Siberia are also reported. It is suggested that the likely source of the perturbation is a magnetic disturbance in the solar wind observed by ISEE 1/2 and IMP 8. The perturbation is interpreted as an impulsive penetration of solar wind plasma on an interplanetary magnetic flux tube occurring through the magnetopause, ending in the low latitude boundary layer.

  4. Identification and characterization of kinetically competent carbinolamine and alpha-iminoglutarate complexes in the glutamate dehydrogenase-catalyzed oxidation of L-glutamate using a multiwavelength transient state approach.

    PubMed

    Maniscalco, S J; Saha, S K; Fisher, H F

    1998-10-13

    A highly constrained and heavily overdetermined multiwavelength transient state kinetic approach has been used to study the oxidative deamination of L-glutamate catalyzed by beef liver glutamate dehydrogenase. Spectra generated using the known enzyme-reduced coenzyme-substrate spectrum served as models for deconvolution of kinetic scan data. Deconvolution of the multiwavelength time course array shows formation of three distinguishable intermediates in the reaction sequence, an ultrablue-shifted complex, an ultrared-shifted complex, and a blue-shifted complex. The ultrablue-shifted entity is identified as the enzyme-NADPH-alpha-iminoglutarate complex (ERI) and the ultrared as the enzyme-NADPH-alpha-carbinolamine complex (ERC). The blue-shifted complex is characterized as the E-NADPH-ketoglutarate species (ERK). The location of these species along the reaction coordinate has been determined and their kinetic competency in the reaction sequence has been established by fitting the concentration time courses of the components for both the alpha-deuterio- and the alpha-protio-L-glutamate reactions to the now highly constrained differential equations derived from a kinetic scheme involving the sequential formation of alpha-iminoglutarate, alpha-carbinolamine, and alpha-ketoglutarate-reduced coenzyme complexes, following the formation of two prehydride transfer complexes. PMID:9772187

  5. Detection of Radio Transients from Supernovae

    NASA Astrophysics Data System (ADS)

    Schmitt, Christian

    2011-05-01

    A core-collapse supernova (SN) would produce an expanding shell of charged particles which interact with the surrounding magnetic field of the progenitor star producing a transient radio pulse. Approximately one supernova event per century is expected in a galaxy. The radio waves emitted are detectable by a new generation of low-frequency radio telescope arrays. We present details of an ongoing search for such events by the Eight-meter-wavelength Transient Array (ETA) and the Long Wavelength Array (LWA).

  6. Members of the NODE (Nanog and Oct4-associated deacetylase) complex and SOX-2 promote the initiation of a natural cellular reprogramming event in vivo

    PubMed Central

    Kagias, Konstantinos; Ahier, Arnaud; Fischer, Nadine; Jarriault, Sophie

    2012-01-01

    Differentiated cells can be forced to change identity, either to directly adopt another differentiated identity or to revert to a pluripotent state. Direct reprogramming events can also occur naturally. We recently characterized such an event in Caenorhabditis elegans, in which a rectal cell switches to a neuronal cell. Here we have used this single-cell paradigm to investigate the molecular requirements of direct cell-type conversion, with a focus on the early steps. Our genetic analyses revealed the requirement of sem-4/Sall, egl-27/Mta, and ceh-6/Oct, members of the NODE complex recently identified in embryonic stem (ES) cells, and of the OCT4 partner sox-2, for the initiation of this natural direct reprogramming event. These four factors have been shown to individually impact on ES cell pluripotency; however, whether they act together to control cellular potential during development remained an open question. We further found that, in addition to acting at the same time, these factors physically associate, suggesting that they could act together as a NODE-like complex during this in vivo process. Finally, we have elucidated the functional domains in EGL-27/MTA that mediate its reprogramming activity in this system and have found that modulation of the posterior HOX protein EGL-5 is a downstream event to allow the initiation of Y identity change. Our data reveal unique in vivo functions in a natural direct reprogramming event for these genes that impact on ES cells pluripotency and suggest that conserved nuclear events could be shared between different cell plasticity phenomena across phyla. PMID:22493276

  7. Members of the NODE (Nanog and Oct4-associated deacetylase) complex and SOX-2 promote the initiation of a natural cellular reprogramming event in vivo.

    PubMed

    Kagias, Konstantinos; Ahier, Arnaud; Fischer, Nadine; Jarriault, Sophie

    2012-04-24

    Differentiated cells can be forced to change identity, either to directly adopt another differentiated identity or to revert to a pluripotent state. Direct reprogramming events can also occur naturally. We recently characterized such an event in Caenorhabditis elegans, in which a rectal cell switches to a neuronal cell. Here we have used this single-cell paradigm to investigate the molecular requirements of direct cell-type conversion, with a focus on the early steps. Our genetic analyses revealed the requirement of sem-4/Sall, egl-27/Mta, and ceh-6/Oct, members of the NODE complex recently identified in embryonic stem (ES) cells, and of the OCT4 partner sox-2, for the initiation of this natural direct reprogramming event. These four factors have been shown to individually impact on ES cell pluripotency; however, whether they act together to control cellular potential during development remained an open question. We further found that, in addition to acting at the same time, these factors physically associate, suggesting that they could act together as a NODE-like complex during this in vivo process. Finally, we have elucidated the functional domains in EGL-27/MTA that mediate its reprogramming activity in this system and have found that modulation of the posterior HOX protein EGL-5 is a downstream event to allow the initiation of Y identity change. Our data reveal unique in vivo functions in a natural direct reprogramming event for these genes that impact on ES cells pluripotency and suggest that conserved nuclear events could be shared between different cell plasticity phenomena across phyla. PMID:22493276

  8. A Case of Transient Global Amnesia

    PubMed Central

    Mccroskey, Aidan L.; Deyerle, Branden A.

    2016-01-01

    Transient global amnesia is a clinical syndrome characterized by the sudden onset of anterograde amnesia, accompanied by repetitive questioning, sometimes with a retrograde component, lasting up to 24 hours, without compromise of other neurologic function. Neuroimaging after an acutetransient global amnesia event often shows transient perturbation of specific hippocampal circuits that are involved in memory processing. Critical clinical distinctions, such as between transient global amnesia and other forms of transient amnesic episodes, as well as important clues to the underlying pathophysiologies are herein reviewed. Finally, we discuss the role of hippocampal insufficiency in the neurobiology of delusions. PMID:27354927

  9. Complex Networks Approach for Analyzing the Correlation of Traditional Chinese Medicine Syndrome Evolvement and Cardiovascular Events in Patients with Stable Coronary Heart Disease

    PubMed Central

    Gao, Zhuye; Li, Siwei; Jiao, Yang; Zhou, Xuezhong; Fu, Changgeng; Shi, Dazhuo; Chen, Keji

    2015-01-01

    This is a multicenter prospective cohort study to analyze the correlation of traditional Chinese medicine (TCM) syndrome evolvement and cardiovascular events in patients with stable coronary heart disease (CHD). The impact of syndrome evolvement on cardiovascular events during the 6-month and 12-month follow-up was analyzed using complex networks approach. Results of verification using Chi-square test showed that the occurrence of cardiovascular events was positively correlated with syndrome evolvement when it evolved from toxic syndrome to Qi deficiency, blood stasis, or sustained toxic syndrome, when it evolved from Qi deficiency to blood stasis, toxic syndrome, or sustained Qi deficiency, and when it evolved from blood stasis to Qi deficiency. Blood stasis, Qi deficiency, and toxic syndrome are important syndrome factors for stable CHD. There are positive correlations between cardiovascular events and syndrome evolution from toxic syndrome to Qi deficiency or blood stasis, from Qi deficiency to blood stasis, or toxic syndrome and from blood stasis to Qi deficiency. These results indicate that stable CHD patients with pathogenesis of toxin consuming Qi, toxin leading to blood stasis, and mutual transformation of Qi deficiency and blood stasis are prone to recurrent cardiovascular events. PMID:25821500

  10. A quasi steady state method for solving transient Darcy flow in complex 3D fractured networks accounting for matrix to fracture flow

    NASA Astrophysics Data System (ADS)

    Nœtinger, B.

    2015-02-01

    Modeling natural Discrete Fracture Networks (DFN) receives more and more attention in applied geosciences, from oil and gas industry, to geothermal recovery and aquifer management. The fractures may be either natural, or artificial in case of well stimulation. Accounting for the flow inside the fracture network, and accounting for the transfers between the matrix and the fractures, with the same level of accuracy is an important issue for calibrating the well architecture and for setting up optimal resources recovery strategies. Recently, we proposed an original method allowing to model transient pressure diffusion in the fracture network only [1]. The matrix was assumed to be impervious. A systematic approximation scheme was built, allowing to model the initial DFN by a set of N unknowns located at each identified intersection between fractures. The higher N, the higher the accuracy of the model. The main assumption was using a quasi steady state hypothesis, that states that the characteristic diffusion time over one single fracture is negligible compared with the characteristic time of the macroscopic problem, e.g. change of boundary conditions. In that context, the lowest order approximation N = 1 has the form of solving a transient problem in a resistor/capacitor network, a so-called pipe network. Its topology is the same as the network of geometrical intersections between fractures. In this paper, we generalize this approach in order to account for fluxes from matrix to fractures. The quasi steady state hypothesis at the fracture level is still kept. Then, we show that in the case of well separated time scales between matrix and fractures, the preceding model needs only to be slightly modified in order to incorporate these fluxes. The additional knowledge of the so-called matrix to fracture transfer function allows to modify the mass matrix that becomes a time convolution operator. This is reminiscent of existing space averaged transient dual porosity models.

  11. Time domain signal-averaged electrocardiogram in predicting arrhythmic events after myocardial infarction: role of the duration of the filtered QRS complex.

    PubMed

    Bruna, C; Vado, A; Rossetti, G; Racca, E; Borello, V; Cherasco, E; Isoardi, D; Uslenghi, E

    1996-12-01

    Several studies showed that time domain analysis of the signal-averaged ECG may identify groups of patients with low and high risk for arrhythmic events after myocardial infarction (MI). However, the signal averaging methods were not uniform and the definition of abnormal signal-averaged ECG was empiric. To identify the best quantitative signal-averaged variable in predicting arrhythmic events (sustained ventricular tachycardia, ventricular fibrillation and witnessed, instantaneous death) 262 patients surviving acute MI were prospectively evaluated. Twelve clinical variables, left ventricular ejection fraction (LVEF), complex ventricular arrhythmias (CVA) on Holter monitoring and three conventional signal-averaged variables (either at 25-250 or 40-250 Hz) were entered in a Cox proportional hazards regression model. During a mean follow-up of 20.3 +/- 13.7 months 16 (6.1%) patients had arrhythmic events. All six signal-averaged variables were independent predictors of arrhythmic events and the filtered QRS duration (fQRSD) > or = 120 ms at 40 Hz high pass filtering resulted the most predictive. In a regression analysis, including the best signal-averaged variable, LVEF and CVA, only fQRSD > or = 120 ms at 40 Hz and LVEF independently predicted arrhythmic events. Sensitivity, specificity, positive predictive value and odds ratio for fQRSD > or = 120 ms at 40 Hz were 63, 90, 29 and 11%, respectively, and for the combination of fQRSD > or = 120 ms at 40 Hz and LVEF < 40%, were 73, 95, 47 and 39%, respectively. In conclusion, the fQRSD > or = 120 ms at 40 Hz best predicts arrhythmic events in the post-infarction period. The combination of signal-averaged ECG and LVEF is recommended to stratify patients at risk of arrhythmic events after MI. PMID:9031532

  12. Evolutionary History of the Live-Bearing Endemic Allotoca diazi Species Complex (Actinopterygii, Goodeinae): Evidence of Founder Effect Events in the Mexican Pre-Hispanic Period.

    PubMed

    Corona-Santiago, Diushi Keri; Doadrio, Ignacio; Domínguez-Domínguez, Omar

    2015-01-01

    The evolutionary history of Mexican ichthyofauna has been strongly linked to natural events, and the impact of pre-Hispanic cultures is little known. The live-bearing fish species Allotoca diazi, Allotoca meeki and Allotoca catarinae occur in areas of biological, cultural and economic importance in central Mexico: Pátzcuaro basin, Zirahuén basin, and the Cupatitzio River, respectively. The species are closely related genetically and morphologically, and hypotheses have attempted to explain their systematics and biogeography. Mitochondrial DNA and microsatellite markers were used to investigate the evolutionary history of the complex. The species complex shows minimal genetic differentiation. The separation of A. diazi and A. meeki was dated to 400-7000 years ago, explained by geological and climate events. A bottleneck and reduction of genetic diversity in Allotoca diazi was detected, attributed to recent climate fluctuations and anthropogenic activity. The isolation of A. catarinae occurred ~1900 years ago. No geological events are documented in the area during this period, but the date is contemporary with P'urhépecha culture settlements. This founder effect represents the first evidence of fish species translocation by a pre-Hispanic culture of Mexico. The response of the complex to climate fluctuation, geological changes and human activity in the past and the future according to the ecological niches predictions indicates areas of vulnerability and important information for conservation. The new genetic information showed that the Allotoca diazi complex consist of two genetic groups with an incomplete lineage sorting pattern: Pátzcuaro and Zirahuén lakes, and an introduced population in the Cupatitzio River. PMID:25946217

  13. Evolutionary History of the Live-Bearing Endemic Allotoca diazi Species Complex (Actinopterygii, Goodeinae): Evidence of Founder Effect Events in the Mexican Pre-Hispanic Period

    PubMed Central

    Corona-Santiago, Diushi Keri; Doadrio, Ignacio; Domínguez-Domínguez, Omar

    2015-01-01

    The evolutionary history of Mexican ichthyofauna has been strongly linked to natural events, and the impact of pre-Hispanic cultures is little known. The live-bearing fish species Allotoca diazi, Allotoca meeki and Allotoca catarinae occur in areas of biological, cultural and economic importance in central Mexico: Pátzcuaro basin, Zirahuén basin, and the Cupatitzio River, respectively. The species are closely related genetically and morphologically, and hypotheses have attempted to explain their systematics and biogeography. Mitochondrial DNA and microsatellite markers were used to investigate the evolutionary history of the complex. The species complex shows minimal genetic differentiation. The separation of A. diazi and A. meeki was dated to 400–7000 years ago, explained by geological and climate events. A bottleneck and reduction of genetic diversity in Allotoca diazi was detected, attributed to recent climate fluctuations and anthropogenic activity. The isolation of A. catarinae occurred ~1900 years ago. No geological events are documented in the area during this period, but the date is contemporary with P’urhépecha culture settlements. This founder effect represents the first evidence of fish species translocation by a pre-Hispanic culture of Mexico. The response of the complex to climate fluctuation, geological changes and human activity in the past and the future according to the ecological niches predictions indicates areas of vulnerability and important information for conservation. The new genetic information showed that the Allotoca diazi complex consist of two genetic groups with an incomplete lineage sorting pattern: Pátzcuaro and Zirahuén lakes, and an introduced population in the Cupatitzio River. PMID:25946217

  14. X33 Transient Liftoff Analysis

    NASA Technical Reports Server (NTRS)

    Peck, Jeff; Brunty, Joseph

    2000-01-01

    The successful design of a launch vehicle requires the careful characterization of the various loads the structure will experience over its lifetime. Many of the most demanding load environments occur during the launch/ascent phase of a mission, typically defined as the point of engine start through engine cut off. One of the critical events during the launch phase is the liftoff event. This event imparts high loads on the vehicle due to transient events such as thrust build-up and vehicle release. This paper describes the theory and procedures used to calculate structural loads due to the liftoff event for the Lockheed-Martin X33 technology demonstrator vehicle. These procedures were developed at NASA's Marshall Space Flight Center and verified previously on other advanced launch system concepts and the Space Shuttle system.

  15. Single Event Effects (SEE) for Power Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)

    NASA Technical Reports Server (NTRS)

    Lauenstein, Jean-Marie

    2011-01-01

    Single-event gate rupture (SEGR) continues to be a key failure mode in power MOSFETs. (1) SEGR is complex, making rate prediction difficult SEGR mechanism has two main components: (1) Oxide damage-- Reduces field required for rupture (2) Epilayer response -- Creates transient high field across the oxide.

  16. ATP Depletion Via Mitochondrial F1F0 Complex by Lethal Factor is an Early Event in B. Anthracis-Induced Sudden Cell Death.

    PubMed

    Woodberry, Mitchell W; Aguilera-Aguirre, Leopoldo; Bacsi, Attila; Chopra, Ashok K; Kurosky, Alexander; Peterson, Johnny W; Boldogh, Istvan

    2009-01-01

    Bacillus anthracis' primary virulence factor is a tripartite anthrax toxin consisting of edema factor (EF), lethal factor (LF) and protective antigen (PA). In complex with PA, EF and LF are internalized via receptor-mediated endocytosis. EF is a calmodulin-dependent adenylate cyclase that induces tissue edema. LF is a zinc-metalloprotease that cleaves members of mitogen-activated protein kinase kinases. Lethal toxin (LT: PA plus LF)-induced death of macrophages is primarily attributed to expression of the sensitive Nalp1b allele, inflammasome formation and activation of caspase-1, but early events that initiate these processes are unknown. Here we provide evidence that an early essential event in pyroptosis of alveolar macrophages is LF-mediated depletion of cellular ATP. The underlying mechanism involves interaction of LF with F1F0-complex gamma and beta subunits leading to increased ATPase activity in mitochondria. In support, mitochondrial DNA-depleted MH-S cells have decreased F1F0 ATPase activity due to the lack of F06 and F08 polypeptides and show increased resistance to LT. We conclude that ATP depletion is an important early event in LT-induced sudden cell death and its prevention increases survival of toxin-sensitive cells. PMID:26124678

  17. Implementing a Real-time Complex Event Stream Processing System to Help Identify Potential Participants in Clinical and Translational Research Studies.

    PubMed

    Weber, Susan; Lowe, Henry J; Malunjkar, Sanjay; Quinn, James

    2010-01-01

    Event Stream Processing is a computational approach to the problem of how to infer the occurrence of an event from a data stream in real time without reference to a database. This paper describes how we implemented this technology on the STRIDE platform to address the challenge of real time notification of patients presenting in the Emergency Department (ED) who potentially meet eligibility criteria for a clinical study. The system was evaluated against a standalone legacy alerting system and found to perform adequately. While our initial use of this technology was focused on relatively simple alerts, the system is extensible and has the potential to provide enterprise-level research alerting services supporting more complex scenarios. PMID:21347023

  18. News CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events

    NASA Astrophysics Data System (ADS)

    2010-09-01

    CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events

  19. Complex life histories of fishes revealed through natural information storage devices: case studies of diadromous events as recorded by otoliths

    NASA Astrophysics Data System (ADS)

    Elfman, M.; Limburg, K. E.; Kristiansson, P.; Svedäng, H.; Westin, L.; Wickström, H.; Malmqvist, K.; Pallon, J.

    2000-03-01

    Diadromous fishes - species that move across salinity gradients as part of their life repertoire - form a major part of coastal and inland fisheries. Conventional mark-recapture techniques have long been used to track their movements, but give incomplete information at best. On the other hand, otoliths (ear-stones) of fishes can provide a complete record of major life history events, as reflected both in their microstructure and elemental composition. Strontium, which substitutes for calcium in the aragonite matrix of otoliths, is a powerful tracer of salinity histories in many migratory fishes. We measured Sr and Ca with a nuclear microprobe (PIXE) and show examples (eel, Anguilla anguilla; brown trout, Salmo trutta; American shad, Alosa sapidissima) of how the technique has solved several mysteries within fisheries biology.

  20. Transient competitive complexation in biological kinetic isotope fractionation explains non-steady isotopic effects: Theory and application to denitrification in soils

    SciTech Connect

    Maggi, F.M.; Riley, W.J.

    2009-06-01

    The theoretical formulation of biological kinetic reactions in isotopic applications often assume first-order or Michaelis-Menten-Monod kinetics under the quasi-steady-state assumption to simplify the system kinetics. However, isotopic e ects have the same order of magnitude as the potential error introduced by these simpli cations. Both formulations lead to a constant fractionation factor which may yield incorrect estimations of the isotopic effect and a misleading interpretation of the isotopic signature of a reaction. We have analyzed the isotopic signature of denitri cation in biogeochemical soil systems by Menyailo and Hungate [2006], where high {sup 15}N{sub 2}O enrichment during N{sub 2}O production and inverse isotope fractionation during N{sub 2}O consumption could not be explained with first-order kinetics and the Rayleigh equation, or with the quasi-steady-state Michaelis-Menten-Monod kinetics. When the quasi-steady-state assumption was relaxed, transient Michaelis-Menten-Monod kinetics accurately reproduced the observations and aided in interpretation of experimental isotopic signatures. These results may imply a substantial revision in using the Rayleigh equation for interpretation of isotopic signatures and in modeling biological kinetic isotope fractionation with first-order kinetics or quasi-steady-state Michaelis-Menten-Monod kinetics.

  1. Transient voltage oscillations in coils

    SciTech Connect

    Chowdhuri, P.

    1985-01-01

    Magnet coils may be excited into internal voltage oscillations by transient voltages. Such oscillations may electrically stress the magnet's dielectric components to many times its normal stress. This may precipitate a dielectric failure, and the attendant prolonged loss of service and costly repair work. Therefore, it is important to know the natural frequencies of oscillations of a magnet during the design stage, and to determine whether the expected switching transient voltages can excite the magnet into high-voltage internal oscillations. The series capacitance of a winding significantly affects its natural frequencies. However, the series capacitance is difficult to calculate, because it may comprise complex capacitance network, consisting of intra- and inter-coil turn-to-turn capacitances of the coil sections. A method of calculating the series capacitance of a winding is proposed. This method is rigorous but simple to execute. The time-varying transient voltages along the winding are also calculated.

  2. A stable isotope approach for source apportionment of chlorinated ethene plumes at a complex multi-contamination events urban site.

    PubMed

    Nijenhuis, Ivonne; Schmidt, Marie; Pellegatti, Eleonora; Paramatti, Enrico; Richnow, Hans Hermann; Gargini, Alessandro

    2013-10-01

    The stable carbon isotope composition of chlorinated aliphatic compounds such as chlorinated methanes, ethanes and ethenes was examined as an intrinsic fingerprint for apportionment of sources. A complex field site located in Ferrara (Italy), with more than 50years history of use of chlorinated aliphatic compounds, was investigated in order to assess contamination sources. Several contamination plumes were found in a complex alluvial sandy multi-aquifer system close to the river Po; sources are represented by uncontained former industrial and municipal dump sites as well as by spills at industrial areas. The carbon stable isotope signature allowed distinguishing 2 major sources of contaminants. One source of chlorinated aliphatic contaminants was strongly depleted in ¹³C (<-60‰) suggesting production lines which have used depleted methane for synthesis. The other source had typical carbon isotope compositions of >-40‰ which is commonly observed in recent production of chlorinated solvents. The degradation processes in the plumes could be traced interpreting the isotope enrichment and depletion of parent and daughter compounds, respectively. We demonstrate that, under specific production conditions, namely when highly chlorinated ethenes are produced as by-product during chloromethanes production, ¹³C depleted fingerprinting of contaminants can be obtained and this can be used to track sources and address the responsible party of the pollution in urban areas. PMID:24077332

  3. Temporal evolution of a hydrothermal system in Kusatsu-Shirane Volcano, Japan, inferred from the complex frequencies of long-period events

    USGS Publications Warehouse

    Kumagai, H.; Chouet, B.A.; Nakano, M.

    2002-01-01

    We present a detailed description of temporal variations in the complex frequencies of long-period (LP) events observed at Kusatsu-Shirane Volcano. Using the Sompi method, we analyze 35 LP events that occurred during the period from August 1992 through January 1993. The observed temporal variations in the complex frequencies can be divided into three periods. During the first period the dominant frequency rapidly decreases from 5 to 1 Hz, and Q of the dominant spectral peak remains roughly constant with an average value near 100. During the second period the dominant frequency gradually increases up to 3 Hz, and Q gradually decreases from 160 to 30. During the third period the dominant frequency increases more rapidly from 3 to 5 Hz, and Q shows an abrupt increase at the beginning of this period and then remains roughly constant with an average value near 100. Such temporal variations can be consistently explained by the dynamic response of a hydrothermal crack to a magmatic heat pulse. During the first period, crack growth occurs in response to the overall pressure increase in the hydrothermal system caused by the heat pulse. Once crack formation is complete, heat gradually changes the fluid in the crack from a wet misty gas to a dry gas during the second period. As heating of the hydrothermal system gradually subsides, the overall pressure in this system starts to decrease, causing the collapse of the crack during the third period.

  4. Study of magnetic transient variations signature at equatorial region

    NASA Astrophysics Data System (ADS)

    Santos, J.; Trivedi, N.; Dutra, S.

    Transient variations in the H magnetic field component of magnetograms at high latitude are a common feature. They are associated with interaction process between solar wind and Earth's magnetic field. Abrupt changes in the solar wind interacting with Earth's magnetic field generate Alfvén and fast mode waves. The Alfvén wave doesn't propagate in the direction perpendicular to the geomagnetic field, so equatorial signatures are probably caused by fast mode waves. On the other hand, complex signatures observed at high latitudes represent a composition of Alfvén and fast mode waves. A second suggested propagation mechanism to low latitudes is the Earth-ionosphere wave-guide. In this work, geomagnetic data from the Brazilian magnetic stations at Belém/Tatuoca (BLM), Eusébio (EUS), Ji-Paraná (JIP), São luis (SLZ) and São Martinho da Serra (SMS) were used to look for equatorial signatures of magnetic transient events. We identified their morphological characteristics and time occurrence distribution. Satellite data (ACE and GOES) were used to see magnetosphere signatures and solar wind and interplanetary magnetic field conditions that increase the probability of occurrence for the equatorial events. Trivedi et al. (2002a) present evidence for corresponding signatures of TCV at Belém, São Luis, and Terezina and other stations under or nearby the equatorial electrojet. The conclusions of Trivedi et al. (2002a) are that equatorial signatures differ greatly from event to event; when the high-latitude transient events exhibited clear, strong, isolated signatures corresponding to TCVs, they generally detected isolated bipolar compressional signatures at geosynchronous orbit and transient impulses in equatorial ground magnetograms; when high-latitude events were quasiperiodic, weaker, spatially limited, or did not exhibit clear TCV signatures the equatorial signatures are difficult to identify; the equatorial signatures cannot be simply result from remote

  5. Interaction of DPP10a with Kv4.3 channel complex results in a sustained current component of human transient outward current Ito.

    PubMed

    Turnow, K; Metzner, K; Cotella, D; Morales, M J; Schaefer, M; Christ, T; Ravens, U; Wettwer, E; Kämmerer, S

    2015-03-01

    The sustained component of the K(+) outward current in human atrial myocytes is believed to be due to the slowly inactivating ultra-rapid potassium current I Kur and not to the fast inactivating transient outward current Ito. Here we provide evidence for contribution of Ito to this late current due to the effects of dipeptidyl peptidase-like protein (DPP) 10 (DPP10a) interacting with Kv4.3 channels. We studied the late current component of Ito in human atrial myocytes and CHO cells co-expressing Kv4.3 or Kv4.3/KChIP2 (control) and DPP proteins using voltage-clamp technique and a pharmacological approach. A voltage dependent and slowly inactivating late current (43% of peak amplitude) could be observed in atrial myocytes. We found a similar current in CHO cells expressing Kv4.3/KChIP2 + DPP10a, but not in cells co-expressing Kv4.3 + DPP or Kv4.3/KChIP2 + DPP6-S. Assuming that DPP10a influences atrial Ito, we detected DPP10 expression of three alternatively spliced mRNAs, DPP10 protein and colocalization of Kv4.3 and DPP10 proteins in human atrial myocytes. DPP10a did not affect properties of expressed Kv1.5 excluding a contribution to the sustained IKur in atrial cells. To test for the contribution of Kv4-based Ito on sustained K(+) outward currents in human atrial myocytes, we used 4-AP to block IKur, in combination with Heteropoda toxin 2 to block Kv4 channels. We could clearly separate an Ito fraction of about 19% contributing to the late current in atrial myocytes. Thus, the interaction of DPP10a, expressed in human atrium, with Kv4.3 channels generates a sustained current component of Ito, which may affect late repolarization phase of atrial action potentials. PMID:25600224

  6. Extracting mineral system event histories from geophysical and geochemical data in geologically complex terrain - an example from the southeastern Fennoscandian Shield.

    NASA Astrophysics Data System (ADS)

    Sorjonen-Ward, Peter; Kontinen, Asko; Lerssi, Jouni; Mertanen, Satu; Molnar, Ferenc; O'Brien, Hugh; Pohjolainen, Esa; Halla, Jaana; Korhonen, Fawna; Mattila, Jussi

    2015-04-01

    The mineral systems concept is intended to extend and inform exploration capability, through understanding processes of metal extraction, transport and precipitation within a well-defined architectural framework, as opposed to simple - or even sophisticated - targeting of geophysical or geochemical anomalies. Given that geophysical and geochemical data represent a summation of all events and processes that have affected a body of rock, the use of advanced inversion techniques could be impeded unless we can extract an accurate event history and derive a comprehensive understanding of the history of hydrothermal events and their structural framework, even in a qualitative sense. In ideal cases, we may be able to place age constraints using isotopes or paleomagnetism, if hydrothermal mineral reactions enhance (or disperse) geochemical and geophysical signals. Given a the tendency for deformation in the brittle regime to occur preferentially by reactivation of existing zones of weakness, we might also expect a progressive linear enhancement or dilution of anomalies, where fluid-flow is focused within permeable fault zones. We illustrate these issues through an analysis of event histories and their relationship to diverse mineralization styles and episodes in the southeastern part of the Fennoscandian Shield, where the oldest mineral systems are represented by orogenic gold deposits in Neoarchean greenstone belts and the youngest events are recorded locally by Paleozoic crystallization of uraninite in repeatedly reactivated fault zones. The Neoarchean Karelian craton was subjected to thermal reworking as the foreland terrain to the 1.9-1.8 Ga Svecofennian Orogeny, as demonstrated by resetting of K-Ar, Ar-Ar, Rb-Sr and locally Pb-Pb isotopic systems in feldspars and pyrite, both within gold deposits, and regionally. However, retention of Archean strain patterns and observations of the strain state of Proterozoifc dyke swarms indicate an essentially brittle response, with

  7. Out of Arabia: a complex biogeographic history of multiple vicariance and dispersal events in the gecko genus Hemidactylus (Reptilia: Gekkonidae).

    PubMed

    Smíd, Jiří; Carranza, Salvador; Kratochvíl, Lukáš; Gvoždík, Václav; Nasher, Abdul Karim; Moravec, Jiří

    2013-01-01

    The geological history of the Arabian Peninsula has played a crucial role in shaping current diversity and distribution patterns of many Arabian and African faunal elements. The gecko genus Hemidactylus is not an exception. In this study, we provide an insight into the phylogeny and systematics of 45 recognized species of the so-called Arid clade of the genus Hemidactylus from Arabia, the Horn of Africa, the Levant and Iran. The material comprises 358 specimens sequenced for up to two mitochondrial (12S rRNA, cytochrome b) and four nuclear (mc1r, cmos, rag1, rag2) genes with 4766 bp of the concatenated alignment length. A robust calibrated phylogeny and reconstruction of historical biogeography are inferred. We link the history of this genus with major geological events that occurred in the region within the last 30 million years. Two basal divergences correspond with the break-ups of the Arabian and African landmasses and subsequent separation of Socotra from the Arabian mainland, respectively, segregating the genus by means of vicariance. Formation of the Red Sea led to isolation and subsequent radiation in the Arabian Peninsula, which was followed by multiple independent expansions: 13.1 Ma to Iran; 9.8 Ma to NE Africa; 8.2 to Socotra Archipelago; 7-7.3 Ma two colonizations to the Near East; 5.9 Ma to NE Africa; and 4.1 to Socotra. Moreover, using multiple genetic markers we detected cryptic diversity within the genus, particularly in south-western Arabia and the Ethiopian highlands, and confirmed the existence of at least seven new species in the area. These findings highlight the role of Arabia and the Horn of Africa as an important Hemidactylus diversity hotspot. PMID:23724016

  8. Out of Arabia: A Complex Biogeographic History of Multiple Vicariance and Dispersal Events in the Gecko Genus Hemidactylus (Reptilia: Gekkonidae)

    PubMed Central

    Šmíd, Jiří; Carranza, Salvador; Kratochvíl, Lukáš; Gvoždík, Václav; Nasher, Abdul Karim; Moravec, Jiří

    2013-01-01

    The geological history of the Arabian Peninsula has played a crucial role in shaping current diversity and distribution patterns of many Arabian and African faunal elements. The gecko genus Hemidactylus is not an exception. In this study, we provide an insight into the phylogeny and systematics of 45 recognized species of the so-called Arid clade of the genus Hemidactylus from Arabia, the Horn of Africa, the Levant and Iran. The material comprises 358 specimens sequenced for up to two mitochondrial (12S rRNA, cytochrome b) and four nuclear (mc1r, cmos, rag1, rag2) genes with 4766 bp of the concatenated alignment length. A robust calibrated phylogeny and reconstruction of historical biogeography are inferred. We link the history of this genus with major geological events that occurred in the region within the last 30 million years. Two basal divergences correspond with the break-ups of the Arabian and African landmasses and subsequent separation of Socotra from the Arabian mainland, respectively, segregating the genus by means of vicariance. Formation of the Red Sea led to isolation and subsequent radiation in the Arabian Peninsula, which was followed by multiple independent expansions: 13.1 Ma to Iran; 9.8 Ma to NE Africa; 8.2 to Socotra Archipelago; 7–7.3 Ma two colonizations to the Near East; 5.9 Ma to NE Africa; and 4.1 to Socotra. Moreover, using multiple genetic markers we detected cryptic diversity within the genus, particularly in south-western Arabia and the Ethiopian highlands, and confirmed the existence of at least seven new species in the area. These findings highlight the role of Arabia and the Horn of Africa as an important Hemidactylus diversity hotspot. PMID:23724016

  9. Off-fault damage and acoustic emission distributions during the evolution of structurally complex faults over series of stick-slip events

    NASA Astrophysics Data System (ADS)

    Goebel, T. H. W.; Becker, T. W.; Sammis, C. G.; Dresen, G.; Schorlemmer, D.

    2014-06-01

    Variations in fault structure, for example, surface roughness and deformation zone width, influence the location and dynamics of large earthquakes as well as the distribution of small seismic events. In nature, changes in fault roughness and seismicity characteristics can rarely be studied simultaneously, so that little is known about their interaction and evolution. Here, we investigate the connection between fault structure and near-fault distributions of seismic events over series of stick-slip cycles in the laboratory. We conducted a set of experiments on rough faults that developed from incipient fracture surfaces. We monitored stress and seismic activity which occurred in the form of acoustic emissions (AEs). We determined AE density distributions as a function of fault normal distance based on high-accuracy hypocentre locations during subsequent interslip periods. The characteristics of these distributions were closely connected to different structural units of the faults, that is, the fault core, off-fault and background damage zone. The core deformation zone was characterized by consistently high seismic activity, whereas the off-fault damage zone displayed a power-law decay of seismic activity with increasing distance from the fault core. The exponents of the power-law-distributed off-fault activity increased with successive stick-slip events so that later interslip periods showed a more rapid spatial decay of seismic activity from the fault. The increase in exponents was strongest during the first one to three interslip periods and reached approximately constant values thereafter. The relatively rapid spatial decay of AE events during later interslip periods is likely an expression of decreasing fault zone complexity and roughness. Our results indicate a close relationship between fault structure, stress and seismic off-fault activity. A more extensive mapping of seismic off-fault activity-decay has the potential to significantly advance the

  10. Response of a hydrothermal system to magmatic heat inferred from temporal variations in the complex frequencies of long-period events at Kusatsu-Shirane Volcano, Japan

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.

    2005-01-01

    We investigate temporal variations in the complex frequencies (frequency and quality factor Q) of long-period (LP) events that occurred at Kusatsu-Shirane Volcano, central Japan. We analyze LP waveforms observed at this volcano in the period between 1988 and 1995, which covers a seismically active period between 1989 and 1993. Systematic temporal variations in the complex frequencies are observed in October-November 1989, July-October 1991, and September 1992-January 1993. We use acoustic properties of a crack filled with hydrothermal fluids to interpret the observed temporal variations in the complex frequencies. The temporal variations in October-November 1989 can be divided into two periods, which are explained by a gradual decrease and increase of a gas-volume fraction in a water-steam mixture in a crack, respectively. The temporal variations in July-October 1991 can be also divided into two periods. These variations in the first and second periods are similar to those observed in November 1989 and in September-November 1992, respectively, and are interpreted as drying of a water-steam mixture and misty gas in a crack, respectively. The repeated nature of the temporal variations observed in similar seasons between July and November suggests the existence of seasonality in the occurrence of LP events. This may be caused by a seasonally variable meteoritic water supply to a hydrothermal system, which may have been heated by the flux of volcanic gases from magma beneath this volcano. ?? 2005 Elsevier B.V. All rights reserved.

  11. Study of the thermal internal boundary layer during sea-breeze events in the complex coastal area of Marseille

    NASA Astrophysics Data System (ADS)

    Calmet, Isabelle; Mestayer, Patrice

    2016-02-01

    A revisit of two sea-breeze episodes is presented, based on higher spatial resolution large eddy simulations (LES) of the lower atmosphere over the coastal area of Marseille and measurements obtained during the June 2001 experimental campaign UBL-ESCOMPTE. The focus is on the development of thermal internal boundary layers (TIBL) over a complex topography: the dynamic and thermal mechanisms that contribute to the TIBL growth and its further degeneration into a convective mixed layer, the respective influences of the coast shape, the large-scale flow above and the local low-level slope flows. The high-resolution LES permits exploring the potential temperature and turbulent kinetic energy fields in relation with the evolution of TIBL depth and heat fluxes along representative streamlines. Several theoretical TIBL depth models are further compared to the LES-deduced inversion height and other parameters, leading to a discussion of the relationships between the values of these parameters, the respective influences of the governing physical phenomena, and the TIBL behaviour. A threshold value of 0.35 is proposed for the friction velocity to convective velocity scale ratio u */ w * between the two regimes where the TIBL is either dominated by dynamical kinetic energy production or controlled by buoyancy.

  12. Transient tachypnea - newborn

    MedlinePlus

    TTN; Wet lungs - newborns; Retained fetal lung fluid; Transient RDS; Prolonged transition; Neonatal - transient tachypnea ... As the baby grows in the womb, the lungs make a special fluid. This fluid fills the ...

  13. Transient drainage summary report

    SciTech Connect

    1996-09-01

    This report summarizes the history of transient drainage issues on the Uranium Mill Tailings Remedial Action (UMTRA) Project. It defines and describes the UMTRA Project disposal cell transient drainage process and chronicles UMTRA Project treatment of the transient drainage phenomenon. Section 4.0 includes a conceptual cross section of each UMTRA Project disposal site and summarizes design and construction information, the ground water protection strategy, and the potential for transient drainage.

  14. Probing the many energy-transfer processes in the photosynthetic light-harvesting complex II at 77 K using energy-selective sub-picosecond transient absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Visser, H. M.; Kleima, F. J.; van Stokkum, I. H. M.; van Grondelle, R.; van Amerongen, H.

    1996-10-01

    The dynamics of energy equilibration in the main plant light-harvesting complex, LHCII, at a temperature of 77 K was probed using sub-picosecond excitation pulses at 649, 661, 672 and 682 nm and detection of the resulting difference absorption spectra from 630 to 700 nm. We find three distinct chlorophyll b to chlorophyll a (Chl a) transfer times, of < 0.3, 0.6 and 4-9 ps, respectively. From a comparison of the amplitudes of the bleaching signal, a plausible scheme for the Chl b to Chl a transfer in the LHCII complex is proposed. Two Chl b molecules transfer energy to Chl a in less than 0.3 ps, two Chl b molecules transfer with 0.6 ps and one Chl b has a transfer time of 4-9 ps. In the Chl a absorption region, a 2.4 ps energy-transfer process from a pigment absorbing around 661 nm, and a 0.4 ps process from a pigment absorbing around 672 nm is found. Furthermore, evidence is found for slow, 10-20 ps energy-transfer processes between some of the Chl a molecules. The data are compared to model calculations using the 3.4 Å LHCII monomer structure (containing 5 Chl b and 7 Chl a molecules) and Förster energy transfer. We conclude that the observed energy-transfer rates are consistent with both the preliminary assignment of the Chl identities ( a or b) of Kühlbrandt et al. and a recent proposal for the arrangement of some of the transition dipole moments (Gülen et al.). Singlet-singlet and singlet-triplet annihilation processes are observed in two different experiments, and both these processes occur with time constants of 2-3 and 12-20 ps, suggesting that both annihilation pathways are at least partly limited by slow energy transfer. The wide range of observed time constants in the equilibration, from < 0.3 to ˜ 20 ps, most likely reflects the irregular arrangement of the pigments in the complex, which shows much less symmetry than the recently obtained structure of the peripheral antenna complex of purple bacteria, LH-II (McDermott et al.).

  15. Role of shielding in modulating the effects of solar particle events: Monte Carlo calculation of absorbed dose and DNA complex lesions in different organs

    NASA Technical Reports Server (NTRS)

    Ballarini, F.; Biaggi, M.; De Biaggi, L.; Ferrari, A.; Ottolenghi, A.; Panzarasa, A.; Paretzke, H. G.; Pelliccioni, M.; Sala, P.; Scannicchio, D.; Zankl, M.; Townsend, L. W. (Principal Investigator)

    2004-01-01

    Distributions of absorbed dose and DNA clustered damage yields in various organs and tissues following the October 1989 solar particle event (SPE) were calculated by coupling the FLUKA Monte Carlo transport code with two anthropomorphic phantoms (a mathematical model and a voxel model), with the main aim of quantifying the role of the shielding features in modulating organ doses. The phantoms, which were assumed to be in deep space, were inserted into a shielding box of variable thickness and material and were irradiated with the proton spectra of the October 1989 event. Average numbers of DNA lesions per cell in different organs were calculated by adopting a technique already tested in previous works, consisting of integrating into "condensed-history" Monte Carlo transport codes--such as FLUKA--yields of radiobiological damage, either calculated with "event-by-event" track structure simulations, or taken from experimental works available in the literature. More specifically, the yields of "Complex Lesions" (or "CL", defined and calculated as a clustered DNA damage in a previous work) per unit dose and DNA mass (CL Gy-1 Da-1) due to the various beam components, including those derived from nuclear interactions with the shielding and the human body, were integrated in FLUKA. This provided spatial distributions of CL/cell yields in different organs, as well as distributions of absorbed doses. The contributions of primary protons and secondary hadrons were calculated separately, and the simulations were repeated for values of Al shielding thickness ranging between 1 and 20 g/cm2. Slight differences were found between the two phantom types. Skin and eye lenses were found to receive larger doses with respect to internal organs; however, shielding was more effective for skin and lenses. Secondary particles arising from nuclear interactions were found to have a minor role, although their relative contribution was found to be larger for the Complex Lesions than for the

  16. E-photosynthesis: a comprehensive modeling approach to understand chlorophyll fluorescence transients and other complex dynamic features of photosynthesis in fluctuating light.

    PubMed

    Nedbal, Ladislav; Cervený, Jan; Rascher, Uwe; Schmidt, Henning

    2007-01-01

    Plants are exposed to a temporally and spatially heterogeneous environment, and photosynthesis is well adapted to these fluctuations. Understanding of the complex, non-linear dynamics of photosynthesis in fluctuating light requires novel-modeling approaches that involve not only the primary light and dark biochemical reactions, but also networks of regulatory interactions. This requirement exceeds the capacity of the existing molecular models that are typically reduced to describe a partial process, dynamics of a specific complex or its particular dynamic feature. We propose a concept of comprehensive model that would represent an internally consistent, integral framework combining information on the reduced models that led to its construction. This review explores approaches and tools that exist in engineering, mathematics, and in other domains of biology that can be used to develop a comprehensive model of photosynthesis. Equally important, we investigated techniques by which one can rigorously reduce such a comprehensive model to models of low dimensionality, which preserve dynamic features of interest and, thus, contribute to a better understanding of photosynthesis under natural and thus fluctuating conditions. The web-based platform www.e-photosynthesis.org is introduced as an arena where these concepts and tools are being introduced and tested. PMID:17492490

  17. Communication: Transient anion states of phenol…(H{sub 2}O){sub n} (n = 1, 2) complexes: Search for microsolvation signatures

    SciTech Connect

    Oliveira, Eliane M. de; Lima, Marco A. P.; Freitas, Thiago C.; Coutinho, Kaline; Varella, Márcio T. do N; Canuto, Sylvio; Bettega, Márcio H. F.

    2014-08-07

    We report on the shape resonance spectra of phenol-water clusters, as obtained from elastic electron scattering calculations. Our results, along with virtual orbital analysis, indicate that the well-known indirect mechanism for hydrogen elimination in the gas phase is significantly impacted on by microsolvation, due to the competition between vibronic couplings on the solute and solvent molecules. This fact suggests how relevant the solvation effects could be for the electron-driven damage of biomolecules and the biomass delignification [E. M. de Oliveira et al., Phys. Rev. A 86, 020701(R) (2012)]. We also discuss microsolvation signatures in the differential cross sections that could help to identify the solvated complexes and access the composition of gaseous admixtures of these species.

  18. Transient astronomy with the Gaia satellite.

    PubMed

    Hodgkin, Simon T; Wyrzykowski, Łukasz; Blagorodnova, Nadejda; Koposov, Sergey

    2013-06-13

    Gaia is a cornerstone European Space Agency astrometry space mission and a successor to the Hipparcos mission. Gaia will observe the whole sky for 5 years, providing a serendipitous opportunity for the discovery of large numbers of transient and anomalous events, e.g. supernovae, novae and microlensing events, gamma-ray burst afterglows, fallback supernovae, as well as theoretical or unexpected phenomena. In this paper, we discuss our preparations to use Gaia to search for transients at optical wavelengths, and briefly describe the early detection, classification and prompt publication of anomalous sources. PMID:23630374

  19. Evaluation of 2B31 TRMM-product rain estimates for single precipitation events over a region with complex topographic features

    NASA Astrophysics Data System (ADS)

    Montero-MartíNez, Guillermo; Zarraluqui-Such, VíCtor; GarcíA-GarcíA, Fernando

    2012-01-01

    An evaluation of precipitation estimations on the ground for individual rainfall events was carried out by comparing the 2B31 Tropical Rainfall Measuring Mission (TRMM) product versus a high-density, rain gauge network deployed at the ground over a small (about 1000 km2) study area in a continental region characterized by complex topography and high altitude. This comparison, using categorical analysis, showed a good agreement for several skill parameters most frequently used in works of this type. In this paper, it is concluded that Odds Ratio Skill Score (ORSS) is a more reliable measure of skill for categorical statistics than other scores because it better reflects the agreement between the two data sets. Furthermore, ORSS allows one to test the significance of the results so it is possible to discriminate whether the resulting skill is due to pure chance (ORSS was significant in 70% of the cases studied). Although variance and mean analyses generally showed differences between data sets for both the amount and the distribution of rainfall rate over the study area, least squares fits indicate a very high and quite linear correlation for both the mean rainfall rate (r2 = 0.90) and the maximum amount of precipitation at a given point (r2 = 0.74). It is concluded that 2B31 TRMM data can be used in weather applications for the area studied here and others with complex orographical characteristics and also as a tool in the diagnosis of individual rain events in other regions where there are no other data sources available.

  20. Radio Counterparts to SXR Transients

    NASA Astrophysics Data System (ADS)

    Gary, D. E.

    1999-12-01

    By now several studies have been done on small-scale brightenings seen at radio, UV, EUV, and soft X-ray wavelengths. These are to be reviewed by Kundu in these proceedings. In this talk we concentrate on the radio counterpart of a particular type of brightening---the soft X-ray transient brightenings of Shimizu. These brightenings are associated with active regions, and a study of radio counterparts by White et al. (1995) using Nobeyama data found an excellent correspondence between the 17 GHz and SXR brightenings, both spatially and temporally. However, this study found that both the SXR and microwave emissions could be satisfactorily explained as purely thermal emission, and a search of BATSE hard X-ray data showed no nonthermal counterpart. White et al. (1995) were forced to conclude that the events may be different from flares. A more sensitive search for nonthermal emission was needed, in particular using lower frequency microwaves where the influence of nonthermal electrons would be more easily detected. Gary, Hartl and Shimizu (1997) found 34 SXR transient brightenings over a 10-day period in May 1992, for which OVRO (1-18 GHz) total power data were available. A comparison of the data showed a number of clear nonthermal signatures. In addition, one of the events was seen in the lowest energy (6-9.3 keV) channel of the BATSE SPEC detector, suggesting a connection between the microflares discovered in hard X-rays by Lin et al. (1984). The evidence that SXR transient brightenings are microflares is reviewed in this talk. We also attempt to place other small-scale brightenings in context with regard to SXR transient brightenings and microflares.

  1. 2D dry granular free-surface transient flow over complex topography with obstacles. Part II: Numerical predictions of fluid structures and benchmarking

    NASA Astrophysics Data System (ADS)

    Juez, C.; Caviedes-Voullième, D.; Murillo, J.; García-Navarro, P.

    2014-12-01

    Dense granular flows are present in geophysics and in several industrial processes, which has lead to an increasing interest for the knowledge and understanding of the physics which govern their propagation. For this reason, a wide range of laboratory experiments on gravity-driven flows have been carried out during the last two decades. The present work is focused on geomorphological processes and, following previous work, a series of laboratory studies which constitute a further step in mimicking natural phenomena are described and simulated. Three situations are considered with some common properties: a two-dimensional configuration, variable slope of the topography and the presence of obstacles. The setup and measurement technique employed during the development of these experiments are deeply explained in the companion work. The first experiment is based on a single obstacle, the second one is performed against multiple obstacles and the third one studies the influence of a dike on which overtopping occurs. Due to the impact of the flow against the obstacles, fast moving shocks appear, and a variety of secondary waves emerge. In order to delve into the physics of these types of phenomena, a shock-capturing numerical scheme is used to simulate the cases. The suitability of the mathematical models employed in this work has been previously validated. Comparisons between computed and experimental data are presented for the three cases. The computed results show that the numerical tool is able to predict faithfully the overall behavior of this type of complex dense granular flow.

  2. Disentangling the complex evolutionary history of the Western Palearctic blue tits (Cyanistes spp.) - phylogenomic analyses suggest radiation by multiple colonization events and subsequent isolation.

    PubMed

    Stervander, Martin; Illera, Juan Carlos; Kvist, Laura; Barbosa, Pedro; Keehnen, Naomi P; Pruisscher, Peter; Bensch, Staffan; Hansson, Bengt

    2015-05-01

    Isolated islands and their often unique biota continue to play key roles for understanding the importance of drift, genetic variation and adaptation in the process of population differentiation and speciation. One island system that has inspired and intrigued evolutionary biologists is the blue tit complex (Cyanistes spp.) in Europe and Africa, in particular the complex evolutionary history of the multiple genetically distinct taxa of the Canary Islands. Understanding Afrocanarian colonization events is of particular importance because of recent unconventional suggestions that these island populations acted as source of the widespread population in mainland Africa. We investigated the relationship between mainland and island blue tits using a combination of Sanger sequencing at a population level (20 loci; 12 500 nucleotides) and next-generation sequencing of single population representatives (>3 200 000 nucleotides), analysed in coalescence and phylogenetic frameworks. We found (i) that Afrocanarian blue tits are monophyletic and represent four major clades, (ii) that the blue tit complex has a continental origin and that the Canary Islands were colonized three times, (iii) that all island populations have low genetic variation, indicating low long-term effective population sizes and (iv) that populations on La Palma and in Libya represent relicts of an ancestral North African population. Further, demographic reconstructions revealed (v) that the Canary Islands, conforming to traditional views, hold sink populations, which have not served as source for back colonization of the African mainland. Our study demonstrates the importance of complete taxon sampling and an extensive multimarker study design to obtain robust phylogeographical inferences. PMID:25753616

  3. AN INTERMEDIATE LUMINOSITY TRANSIENT IN NGC 300: THE ERUPTION OF A DUST-ENSHROUDED MASSIVE STAR

    SciTech Connect

    Berger, E.; Soderberg, A. M.; Foley, R. J.; Dupree, A. K.; Chevalier, R. A.; Fransson, C.; Leonard, D. C.; Debes, J. H.; Diamond-Stanic, A. M.; Tremonti, C. A.; Ivans, I. I.; Thompson, I. B.; Simmerer, J.

    2009-07-10

    We present multi-epoch high-resolution optical spectroscopy, UV/radio/X-ray imaging, and archival Hubble and Spitzer observations of an intermediate luminosity optical transient recently discovered in the nearby galaxy NGC 300. We find that the transient (NGC 300 OT2008-1) has a peak absolute magnitude of M{sub bol} {approx} -11.8 mag, intermediate between novae and supernovae, and similar to the recent events M85 OT2006-1 and SN 2008S. Our high-resolution spectra, the first for this event, are dominated by intermediate velocity ({approx}200-1000 km s{sup -1}) hydrogen Balmer lines and Ca II emission and absorption lines that point to a complex circumstellar environment, reminiscent of the yellow hypergiant IRC+10420. In particular, we detect asymmetric Ca II H and K absorption with a broad red wing extending to {approx}10{sup 3} km s{sup -1}, indicative of gas inflow at high velocity (possibly the wind of a massive binary companion). The low luminosity, intermediate velocities, and overall similarity to a known eruptive star indicate that the event did not result in a complete disruption of the progenitor. We identify the progenitor in archival Spitzer observations, with deep upper limits from Hubble data. The spectral energy distribution points to a dust-enshrouded star with a luminosity of about 6 x 10{sup 4} L{sub sun}, indicative of a {approx}10-20 M{sub sun} progenitor (or binary system). This conclusion is in good agreement with our interpretation of the outburst and circumstellar properties. The lack of significant extinction in the transient spectrum indicates that the dust surrounding the progenitor was cleared by the outburst. We thus predict that the progenitor should be eventually visible with Hubble if the transient event marks an evolutionary transition to a dust-free state, or with Spitzer if the event marks a cyclical process of dust formation.

  4. Observations of Solar Radio Transients

    NASA Astrophysics Data System (ADS)

    Paige, Giorla

    2011-05-01

    A low frequency radio telescope has been recently been constructed on the campus of the The College of New Jersey (TCNJ) and has begun conducting observations at 20MHz as part of NASA'a Radio Jove program. This instrument is capable of observations of solar radio emission including strong prompt radio emission associated with solar burst events. We will discuss solar observations conducted with this instrument as well as an effort to conduct coincident observations with the Eight-meter-wavelength Transient Array (ETA) and the Long Wavelength Array (LWA).

  5. Light Echoes of Historic Transients

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Sinnott, B.; Welch, D. L.; Prieto, J. L.; Bianco, F.

    2014-01-01

    Light echoes, light from a variable source scattered off dust, have been observed for over a century. The recent discovery of light echoes around centuries-old supernovae in the Milky Way and the Large Magellanic Cloud have allowed the spectroscopic characterization of these events, even without contemporaneous photometry and spectroscopy using modern instrumentation. Here we review the recent scientific advances using light echoes of ancient and historic transients, and focus on our latest work on SN 1987A's and Eta Carinae's light echoes.

  6. CRTS: An Open Optical Transient Survey.

    NASA Astrophysics Data System (ADS)

    Drake, Andrew J.; Djorgovski, S. G.; Mahabal, A.; Williams, R.; Graham, M. J.; Donalek, C.; Prieto, J. L.; Catelan, M.; Beshore, E.; Larson, S.; Christensen, E.

    2011-01-01

    The Catalina Real-time Transient Survey (CRTS) is an open optical transient survey that covers 3/4 of the entire sky in a search of transient astrophysical phenomena occurring on timescales of minutes to years. Observational data is derived from the three telescopes of the Catalina Sky Survey which cover up to 2,500 square degrees of sky each night. CRTS has so far discovered more that 2000 transient sources including 600 supernovae, 500 dwarf novae and more than 100 Blazars and UV Ceti variables. All data is processed within minutes of observation and discoveries are openly distributed using SkyAlert and VOEvent technologies as well as iPhone, html tables, RSS and Twitter feeds. Events are classified utilizing data from virtual observatory enabled archives, machine learning, and collaborative Citizen science.

  7. Transient Alerts in LSST

    NASA Astrophysics Data System (ADS)

    Kantor, J.

    During LSST observing, transient events will be detected and alerts generated at the LSST Archive Center at NCSA in Champaign-Illinois. As a very high rate of alerts is expected, approaching ˜ 10 million per night, we plan for VOEvent-compliant Distributor/Brokers (http://voevent.org) to be the primary end-points of the full LSST alert streams. End users will then use these Distributor/Brokers to classify and filter events on the stream for those fitting their science goals. These Distributor/Brokers are envisioned to be operated as a community service by third parties who will have signed MOUs with LSST. The exact identification of Distributor/Brokers to receive alerts will be determined as LSST approaches full operations and may change over time, but it is in our interest to identify and coordinate with them as early as possible. LSST will also operate a limited Distributor/Broker with a filtering capability at the Archive Center, to allow alerts to be sent directly to a limited number of entities that for some reason need to have a more direct connection to LSST. This might include, for example, observatories with significant follow-up capabilities whose observing may temporarily be more directly tied to LSST observing. It will let astronomers create simple filters that limit what alerts are ultimately forwarded to them. These user defined filters will be possible to specify using an SQL-like declarative language, or short snippets of (likely Python) code. We emphasize that this LSST-provided capability will be limited, and is not intended to satisfy the wide variety of use cases that a full-fledged public Event Distributor/Broker could. End users will not be able to subscribe to full, unfiltered, alert streams coming directly from LSST. In this session, we will discuss anticipated LSST data rates, and capabilities for alert processing and distribution/brokering. We will clarify what the LSST Observatory will provide versus what we anticipate will be a

  8. Optical & NIR Transient Surveys

    NASA Astrophysics Data System (ADS)

    Cross, Nicholas J. G.; Djorgovski, S. G.

    2012-04-01

    A workshop on Optical & Near Infrared Transients took place during the first afternoon of the Symposium. It ran for two sessions. The first was given over to talks about various current optical and near-infrared transient surveys, focussing on the Vista surveys, the Catalina Real-Time Transient Survey, Pan-STARRS, Gaia, TAOS and TAOS2. The second session was a panel-led discussion about coordinating multi-wavelength surveys and associated follow-ups.

  9. Coronal transient--eruptive prominence of 1980 August 5

    SciTech Connect

    Fisher, R.; Garcia, C.J.; Seagraves, P.

    1981-06-15

    A coronal transient was observed in association with an eruptive prominence event using the Mauna Loa experiment system. The transient, a rarefaction, formed before the acceleration of the eruptive prominence. Upward velocities of various features, as seen in the plane of the sky, show a marked difference as a function of time between the transient and the eruptive prominence. A region of enhanced electron density formed slowly in front of the rarefaction.

  10. Classification of Transient Phenomena in Distribution System using wavelet Transform

    NASA Astrophysics Data System (ADS)

    Sedighi, Alireza

    2014-05-01

    An efficient procedure for classification of transient phenomena in distribution systems is proposed in this paper. The proposed method has been applied to classify some transient phenomena such as inrush current, load switching, capacitor switching and single phase to ground fault. The new scheme is based on wavelet transform algorithm. All of the events for feature extraction and test are simulated using Electro Magnetic Transient Program (EMTP). Results show high accuracy of proposed method.

  11. Exploring the transient sky: from surveys to simulations

    NASA Astrophysics Data System (ADS)

    Carbone, Dario

    2016-01-01

    The transient sky is very important to study the dynamics of the Universe on human timescales. Transient sources are seen in every band of the electromagnetic spectrum, from low radio frequencies to gamma-ray energies, and produced by nearby flare stars to cosmological gamma-ray bursts.We have performed a transient survey of four different fields with the LOw Frequency Array (LOFAR) at 150 MHz. LOFAR is a new generation radio interferometer which is observing at very low radio frequencies, a so far relatively unexplored frequency domain for transient searches. No credible transients were detected in our survey, but we were able to set stringent upper limits on the transient surface density using three new statistical methods. We also calculated the transient surface density as a function of the timescale of the transients, and established that the upper limits we can set vary up to two orders of magnitude for different timescales.We have explored the complex relation between flux density, timescale and transient surface density, and developed a simulation method to calculate the transient rate as a function of both the flux and the duration of transients for different shapes of their lightcurves and for a given observing strategy. This method is independent of the nature of transient sources, and the instrument or the frequency of the observations. Therefore, this provides a tool for transient surveys carried out by current and future observatories across the electromagnetic spectrum.

  12. Transient Response in LMFBR System.

    Energy Science and Technology Software Center (ESTSC)

    1999-04-26

    SSC-L (the Super System Code) calculates the thermohydraulic response of loop-type liquid metal fast breeder reactor (LMFBR) systems during operational, incidental, and accidental transients, especially natural circulation events. Modules simulated and parameters calculated include: core flow rates and temperatures, loop flow rates and temperatures, pump performance, and heat exchanger operation. Additionally, SSC-L accounts for all plant protection and plant control systems. Although the primary emphasis is on transients for safety analysis, SSC-L can be usedmore » for many other applications, such as scoping analysis for plant design and specification of various components. Any number of user-specified loops, pipes, and nodes are permitted. Both single- and two-phase thermal-hydraulics are used in a multi-channel core representation. Inter-assembly flow redistribution is accounted for using a detailed fuel pin model. The heat transport system geometry is user-specified. SSC-L provides steady-state and transient options and a restart capability. Input is free format in a modular structure that makes use of abstract data management techniques.« less

  13. Regulatory Analysis of Reactivity Transients

    SciTech Connect

    Beyer, Carl E.; Clifford, Paul M.; Geelhood, Kenneth J.; Voglewede, John C.

    2009-08-01

    This paper will describe modifications made to the FRAPCON-3 and FRAPTRAN fuel performance codes and models that impact reactivity initiated accident (RIA) analyses. The modified models include an upper bound empirical and best estimate release models for fast transients, and a revised fuel failure model that accounts for ductile and brittle failure. Because experimental data exists for discrete test conditions, the codes and models are used to interpolate and to some extent, to extrapolate these test conditions. An upper bound empirical model for release is used to establish new recommended release fractions for long-lived and short lived (radioactive) isotopes for RIA events in Regulatory Guide 1.183. A best estimate release model is used in FRAPTRAN 1.4 based on grain boundary gas concentrations from FRAPCON-3.4 to predict release for RIA events. Code and model predictions will be compared to failure and release data from RIA tests to demonstrate accuracy.

  14. VOEventNet: Event Messaging for Astronomy

    NASA Astrophysics Data System (ADS)

    Drake, Andrew J.; Djorgovski, G.; Graham, M.; Williams, R.; Mahabal, A.; Donalek, C.; Glikman, E.; Bloom, J.; Vastrand, T.; White, R.; Rabinowitz, D.; Baltay, C.

    2006-12-01

    The time domain remains one of the the least explored areas in modern astronomy. In the near future the next generation of large synoptic sky surveys (Pan-STARRs, Skymapper, LSST) will probe the time dependent nature of the sky by detecting hundreds of thousands of astronomical transients (variable stars, asteroids, GRBs, lensing events). A global event distribution and follow-up network is required to characterize the nature of these transients. For over a year the VOEventNet project has been in the process of implementing a transient event follow-up network which distributes crafted structured data packets called VOEvents. These packets have been designed to be general enough to contain metadata for transients seen at all wavelengths, yet interpretable by robotic telescope systems (which are already automatically responding with follow-up observations). The VOEventNet project currently has transient event follow-up with the Palomar 60 and 200in (Caltech), RAPTOR (LANL), PARITEL and KAIT (UCB) as well as UK telescopes. VOEventNet transient event streams are publicly available. The subscription, publication and reception of VOEvents is implimented with a number of open source software clients. The software and details of how to receive streams of events are available from http://www.voeventnet.org. Current event streams include OGLE microlensing events, SDSS Supernovae, GCN GRBs, Raptor and Palomar-Quest optical transients. In the near future, many additional streams of VOEvents will be available, including optical transients from the ESSENCE, Planet and MOA projects, as well as those from UKIRT and JCMT telescopes. We also expect that transient event alerts will be available from Solar, X-ray and Radio telescopes.

  15. Perception of acoustic transients

    NASA Astrophysics Data System (ADS)

    Howard, J. H., Jr.

    1984-01-01

    The research investigates the role of knowledge based or top-down processing in the perception of nonlinguistic, transient signals. The experiments address issues in transient pattern classification, target observation, attentional focusing, auditory induction, and computer based performance aids. The theoretical significance and naval relevance of the research is considered.

  16. Complex dynamics of small-moderate volcanic events: the example of the 2011 rhyolitic Cordón Caulle eruption, Chile

    NASA Astrophysics Data System (ADS)

    Pistolesi, Marco; Cioni, Raffaello; Bonadonna, Costanza; Elissondo, Manuela; Baumann, Valerie; Bertagnini, Antonella; Chiari, Laura; Gonzales, Rafael; Rosi, Mauro; Francalanci, Lorella

    2015-01-01

    dispersal of the main tephra layers with satellite images, showing that most of the tephra was emitted during the first 72 h of the event. The analyzed juvenile material tightly clusters within the rhyolitic field, with negligible chemical variations through the eruptive sequence. Textural observations reveal that changes in eruption intensity (and consequently in magma ascent velocity within the conduit) and complex interactions between gas-rich and gas-depleted magma portions during ascent resulted in vesicular clasts with variable degrees of shear localization, and possibly in the large heterogeneity of the juvenile material.

  17. Optimized Uncertainty Quantification Algorithm Within a Dynamic Event Tree Framework

    SciTech Connect

    J. W. Nielsen; Akira Tokuhiro; Robert Hiromoto

    2014-06-01

    Methods for developing Phenomenological Identification and Ranking Tables (PIRT) for nuclear power plants have been a useful tool in providing insight into modelling aspects that are important to safety. These methods have involved expert knowledge with regards to reactor plant transients and thermal-hydraulic codes to identify are of highest importance. Quantified PIRT provides for rigorous method for quantifying the phenomena that can have the greatest impact. The transients that are evaluated and the timing of those events are typically developed in collaboration with the Probabilistic Risk Analysis. Though quite effective in evaluating risk, traditional PRA methods lack the capability to evaluate complex dynamic systems where end states may vary as a function of transition time from physical state to physical state . Dynamic PRA (DPRA) methods provide a more rigorous analysis of complex dynamic systems. A limitation of DPRA is its potential for state or combinatorial explosion that grows as a function of the number of components; as well as, the sampling of transition times from state-to-state of the entire system. This paper presents a method for performing QPIRT within a dynamic event tree framework such that timing events which result in the highest probabilities of failure are captured and a QPIRT is performed simultaneously while performing a discrete dynamic event tree evaluation. The resulting simulation results in a formal QPIRT for each end state. The use of dynamic event trees results in state explosion as the number of possible component states increases. This paper utilizes a branch and bound algorithm to optimize the solution of the dynamic event trees. The paper summarizes the methods used to implement the branch-and-bound algorithm in solving the discrete dynamic event trees.

  18. Acute transient deafness representing a negative epileptic phenomenon.

    PubMed

    Shahar, Eli; Ravid, Sarit; Genizi, Jacob; Schif, Aharon

    2010-07-01

    We report herein 2 children who presented with acute deafness heralding an epileptic event manifesting thereafter by loss of consciousness and tonic generalized posturing, possibly reflecting a negative epileptic phenomenon. The first previously healthy male had 2 paroxysmal episodes 7 months apart, starting with acute deafness lasting for a few minutes followed by loss of consciousness and generalized tonic posturing for 10 minutes. Electroencephalography (EEG) during the second episodes demonstrated generalized epileptiform discharges. The second with previously controlled partial complex seizures presented with episodes of complete deafness lasting for a few minutes followed by loss of consciousness and focal tonic posturing lasting 10 minutes. Such acute deafness represented an aura of a focal seizure substantiated by right focal temporal epileptic discharges within the region of the primary auditory cortex. Therefore, EEG should be performed in any case of acute transient deafness, even in the absence of accompanying overt clinical seizures. PMID:20042694

  19. High-energy transients.

    PubMed

    Gehrels, Neil; Cannizzo, John K

    2013-06-13

    We present an overview of high-energy transients in astrophysics, highlighting important advances over the past 50 years. We begin with early discoveries of γ-ray transients, and then delve into physical details associated with a variety of phenomena. We discuss some of the unexpected transients found by Fermi and Swift, many of which are not easily classifiable or in some way challenge conventional wisdom. These objects are important insofar as they underscore the necessity of future, more detailed studies. PMID:23630376

  20. Transient nucleation in glasses

    NASA Technical Reports Server (NTRS)

    Kelton, K. F.

    1991-01-01

    Nucleation rates in condensed systems are frequently not at their steady state values. Such time dependent (or transient) nucleation is most clearly observed in devitrification studies of metallic and silicate glasses. The origin of transient nucleation and its role in the formation and stability of desired phases and microstructures are discussed. Numerical models of nucleation in isothermal and nonisothermal situations, based on the coupled differential equations describing cluster evolution within the classical theory, are presented. The importance of transient nucleation in glass formation and crystallization is discussed.

  1. Spatial and temporal characteristics of transient anomalies on cGPS time series in Taiwan

    NASA Astrophysics Data System (ADS)

    Kuanhsiang Chen, Sean; Hsu, Ya-Ju; Wu, Yih-Min; Chan, Yu-Chang

    2015-04-01

    Transient anomaly on geodetic time series is a key constraint to understand physical behavior and mechanism of natural hazards. We first identify overall transient anomalies in Taiwan recorded by continuous GPS (cGPS) networks. Sparse estimation techniques is applied to estimate quantity of transient signals from cGPS time series. Systematic classification on transients for isolating each signal is established by weighting empirical trigger factors and criterion. Spatial and temporal characteristics of transient anomalies show contribution of seismic events, landslides, and slow slips. Seismic-related transients are sensitive to earthquakes on land (Mw > 5.5) in particular shallow source depths. Landslide-related transients in the Central Range are induced by typhoons and episodic heavy rainfalls. Slow-slip transients show remote triggering of surrounding great earthquakes. Preliminary linking between geodetic transient signals and natural hazards of Taiwan is well described. Unknown transients reveal surface and tectonic process may play important role in crustal deformation.

  2. High energy transients

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.

    1984-01-01

    A meeting was convened on the campus of the University of California at Santa Cruz during the two-week interval July 11 through July 22, 1983. Roughly 100 participants were chosen so as to give broad representation to all aspects of high energy transients. Ten morning review sessions were held in which invited speakers discussed the current status of observations and theory of the above subjects. Afternoon workshops were also held, usually more than one per day, to informally review various technical aspects of transients, confront shortcomings in theoretical models, and to propose productive courses for future research. Special attention was also given to the instrumentation used to study high energy transient and the characteristics and goals of a dedicated space mission to study transients in the next decade were determined. A listing of articles written by various members of the workshop is included.

  3. Gamma ray transients

    NASA Technical Reports Server (NTRS)

    Cline, Thomas L.

    1987-01-01

    The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients.

  4. Probabilistic Hazard for Seismically-Induced Tsunamis in Complex Tectonic Contexts: Event Tree Approach to Seismic Source Variability and Practical Feasibility of Inundation Maps

    NASA Astrophysics Data System (ADS)

    Lorito, Stefano; Selva, Jacopo; Basili, Roberto; Romano, Fabrizio; Tiberti, Mara Monica; Piatanesi, Alessio

    2014-05-01

    Probabilistic Tsunami Hazard Analysis (PTHA) rests on computationally demanding numerical simulations of the tsunami generation and propagation up to the inundated coastline. We here focus on tsunamis generated by the co-seismic sea floor displacement, which constitute the vast majority of the observed tsunami events, i.e. on Seismic PTHA (SPTHA). For incorporating the full expected seismic source variability, aiming at a complete SPTHA, a very large number of numerical tsunami scenarios is typically needed, especially for complex tectonic contexts, where SPTHA is not dominated by large subduction earthquakes only. Here, we propose a viable approach for reducing the number of simulations for a given set of input earthquakes representing the modelled aleatory uncertainties of the seismic rupture parameters. Our approach is based on a preliminary analysis of the SPTHA of maximum offshore wave height (HMax) at a given target location, and assuming computationally cheap linear propagation. We start with defining an operational SPTHA framework in which we then introduce a simplified Event Tree approach, combined with a Green's functions approach, for obtaining a first controlled sampling and reduction of the effective source parameter space size. We then apply a two-stage filtering procedure to the 'linear' SPTHA results. The first filter identifies and discards all the sources producing a negligible contribution at the target location, for example the smallest earthquakes or those directing most of tsunami energy elsewhere. The second filter performs a cluster analysis aimed at selecting groups of source parameters producing comparable HMax profiles for each earthquake magnitude at the given test site. We thus select a limited set of sources that is subsequently used for calculating 'nonlinear' probabilistic inundation maps at the target location. We find that the optimal subset of simulations needed for inundation calculations can be obtained basing on just the

  5. PRISMATIC CORE COUPLED TRANSIENT BENCHMARK

    SciTech Connect

    J. Ortensi; M.A. Pope; G. Strydom; R.S. Sen; M.D. DeHart; H.D. Gougar; C. Ellis; A. Baxter; V. Seker; T.J. Downar; K. Vierow; K. Ivanov

    2011-06-01

    The Prismatic Modular Reactor (PMR) is one of the High Temperature Reactor (HTR) design concepts that have existed for some time. Several prismatic units have operated in the world (DRAGON, Fort St. Vrain, Peach Bottom) and one unit is still in operation (HTTR). The deterministic neutronics and thermal-fluids transient analysis tools and methods currently available for the design and analysis of PMRs have lagged behind the state of the art compared to LWR reactor technologies. This has motivated the development of more accurate and efficient tools for the design and safety evaluations of the PMR. In addition to the work invested in new methods, it is essential to develop appropriate benchmarks to verify and validate the new methods in computer codes. The purpose of this benchmark is to establish a well-defined problem, based on a common given set of data, to compare methods and tools in core simulation and thermal hydraulics analysis with a specific focus on transient events. The benchmark-working group is currently seeking OECD/NEA sponsorship. This benchmark is being pursued and is heavily based on the success of the PBMR-400 exercise.

  6. Picosecond spectroscopy of charge-transfer processes. Photochemistry of anthracene-tetranitromethane EDA complexes

    NASA Astrophysics Data System (ADS)

    Masnovi, J. M.; Huffman, J. C.; Kochi, J. K.; Hilinski, E. F.; Rentzepis, P. M.

    1984-04-01

    The temporal sequence of events that follow 532 nm excitation of electron donor-acceptor, EDA, complexes of several substituted anthracenes with tetranitromethane is monitored by means of picosecond spectroscopy. Excitation of the charge-transfer band of these EDA complexes produces high yields of 1 : 1 adducts. Absorption spectra and kinetics of the transient species involved in these photochemical reactions provide the basis for elucidation of the reaction mechanism following charge-transfer excitation to the ion pairs.

  7. Fluid dynamics beneath a wet volcano inferred from the complex frequencies of long-period (LP) events: An example from Papandayan volcano, West Java, Indonesia during the 2011 seismic unrest

    NASA Astrophysics Data System (ADS)

    Kamil Syahbana, Devy; Caudron, Corentin; Jousset, Philippe; Lecocq, Thomas; Camelbeeck, Thierry; Bernard, Alain; Surono, Surono

    2014-05-01

    We present results of our study aiming at understanding the dynamics of fluids beneath a wet volcano through the analysis of swarms of long-period (LP) events accompanying the 2011 seismic unrest at Papandayan volcano, West Java, Indonesia. Prior to this unrest, we measured a large amount (100%) of CO2 in the ground at the summit crater, however with very low value of SO2 (less than 10 tons/day). Increase in volcanic activity was also observed from the records of a tiltmeter. A long-term inflation was followed by an abrupt deflation which was concurrent with the swarms of LP events. Hereafter, swarms of volcano-tectonic (VT) and local-tectonic (LT) earthquakes started. We focus here on analyzing the LP events with the following manner. First, we estimate the source location of LP events by applying a non-linear hypocenter algorithm including topography. We then study the waveforms and spectral characteristics of LP events and investigate whether or not these events are due to source effect. We compute the complex frequencies (f and Q) for the coda of the LP events using the Sompi method and subsequently, we estimate the physical processes related to the observed temporal variations in the complex frequencies by following the fluid-filled crack model. We divide the swarms of LP events into two periods. The first period occurred between June and July 2011 (48 LP events) while the second period started from September to October 2011 (36 LP events). The dominant frequencies (f) of LP events observed during these periods range between 1.1 and 6.2 Hz while the attenuation factors (Q) are widely scattered between 20 and 400. We estimate the compositions of fluids inside the crack during both periods as either water foam (mixtures of water and H2O gas/steam) or misty gas (mixtures of water droplets and H2O gas/steam). We finally suggest that if an eruption would have taken place following the 2011 unrest, it would have been in phreatic style rather than magmatic style. The

  8. Concurrent detection of transient faults in microprocessors

    SciTech Connect

    Khan, M.Z.

    1989-01-01

    A large number of errors in digital systems are due to the presence of transient faults. This is especially true of microprocessor-based systems working in a radiation environment that experience transient faults due to single event upsets. These upsets cause a temporary change in the state of the system without any permanent damage. Because of their random and non-recurring nature, transient faults are difficult to detect and isolate, hence they become a source of major concern, especially in critical real-time application areas. Concurrent detection of these errors is necessary for real-time operation. Most existing fault tolerance schemes either use redundancy to mask effects of transient faults or monitor the system for abnormal operations and then perform recovery operation. Although very effective, redundancy schemes incur substantial overhead that makes them unsuitable for small systems. Most monitoring schemes, on the other hand, only detect control flow errors. A new approach called Concurrent Processor Monitoring for on-line detection of transient faults is proposed that attempts to achieve higher error coverage with small error detection latency. The concept of the execution profile of an instruction is defined and is used for detecting control flow and execution errors. To implement this scheme, a watchdog processor is designed for monitoring operations of the main processor. The effectiveness of this technique is demonstrated through computer simulations.

  9. The LOFAR Transients Pipeline

    NASA Astrophysics Data System (ADS)

    Swinbank, John D.; Staley, Tim D.; Molenaar, Gijs J.; Rol, Evert; Rowlinson, Antonia; Scheers, Bart; Spreeuw, Hanno; Bell, Martin E.; Broderick, Jess W.; Carbone, Dario; Garsden, Hugh; van der Horst, Alexander J.; Law, Casey J.; Wise, Michael; Breton, Rene P.; Cendes, Yvette; Corbel, Stéphane; Eislöffel, Jochen; Falcke, Heino; Fender, Rob; Grießmeier, Jean-Mathias; Hessels, Jason W. T.; Stappers, Benjamin W.; Stewart, Adam J.; Wijers, Ralph A. M. J.; Wijnands, Rudy; Zarka, Philippe

    2015-06-01

    Current and future astronomical survey facilities provide a remarkably rich opportunity for transient astronomy, combining unprecedented fields of view with high sensitivity and the ability to access previously unexplored wavelength regimes. This is particularly true of LOFAR, a recently-commissioned, low-frequency radio interferometer, based in the Netherlands and with stations across Europe. The identification of and response to transients is one of LOFAR's key science goals. However, the large data volumes which LOFAR produces, combined with the scientific requirement for rapid response, make automation essential. To support this, we have developed the LOFAR Transients Pipeline, or TraP. The TraP ingests multi-frequency image data from LOFAR or other instruments and searches it for transients and variables, providing automatic alerts of significant detections and populating a lightcurve database for further analysis by astronomers. Here, we discuss the scientific goals of the TraP and how it has been designed to meet them. We describe its implementation, including both the algorithms adopted to maximize performance as well as the development methodology used to ensure it is robust and reliable, particularly in the presence of artefacts typical of radio astronomy imaging. Finally, we report on a series of tests of the pipeline carried out using simulated LOFAR observations with a known population of transients.

  10. Solar transients in the outer heliosphere and interstellar medium

    NASA Astrophysics Data System (ADS)

    Richardson, John

    2016-07-01

    The Voyager spacecraft have observed the evolution of solar transients throughout the heliosphere and now into the interstellar medium. The original idea that the heliospheric radio emission was cause by large solar events now seems confirmed. Plasma and radio waves in the interstellar medium are associated with shocks observed in the magnetic field data and changes in the cosmic ray intensities and anisotropies. Voyager 2 has observed MIRs in the heliosheath which may drive these events at V1. We show the Voyager data from the heliosheath and interstellar medium and try to relate observed transients to events observed at the sun and in the inner heliosphere.

  11. A New Type of X-ray Transient?

    NASA Astrophysics Data System (ADS)

    Bauer, Franz E.; CDFS Transient Team

    2016-01-01

    During an extension of the Chandra Deep Field-South (CDF-S) survey to 7Ms, a relatively bright transient event in a region with no previous X-ray emission. The X-ray light curve of the event is significantly fainter than the X-ray afterglows associated with known Gamma-ray Bursts (GRBs). Several deep optical follow-up constraints rule out a variety of possible explanations (known supernovae, GRBs, most Galactic transients). Although the implied rates are uncertain, similar events could potentially be more common than currently observable GRBs.

  12. Estimating Transient Pressure Surges in Cryogenic Systems

    NASA Technical Reports Server (NTRS)

    Pfister, P.; Gunnerson, F.; Hosler, E.

    1986-01-01

    Potentially-damaging pressure waves anticipated and, therefore, avoided. Mathematical model developed for prediction of pressure behavior in single-and two-phase cryogenic systems. Transient liquid-flow analysis modified to incorporate behavior of vapor bubbles and used to predict maximum pressure in cryogenic transfer systems consisting of complex pipe and valve arrangements under both steady-state and transient conditions. Simulation compared favorably with data obtained during transfer of liquid oxygen from ground storage tanks to Space Shuttle orbiter external tanks. Program written in FORTRAN 77 for batch execution.

  13. Fluid dynamics inside a "wet" volcano inferred from the complex frequencies of long-period (LP) events: An example from Papandayan volcano, West Java, Indonesia, during the 2011 seismic unrest

    NASA Astrophysics Data System (ADS)

    Syahbana, Devy; Caudron, Corentin; Jousset, Philippe; Lecocq, Thomas; Camelbeck, Thierry; Bernard, Alain; Surono, Surono

    2015-04-01

    We present results of our study aimed at understanding the dynamics of fluids inside a "wet" volcano through the analysis of swarms of long-period (LP) events accompanying the 2011 seismic unrest at Papandayan volcano, West Java, Indonesia. Prior to this unrest, we measured an extremely high percentage (100 %) of CO2 in the ground at the summit crater, however with a very low value of SO2 flux (~6 tons/day). Increase in volcanic activity was also observed from the records of a tiltmeter. A long-term inflation was followed by an abrupt deflation that took place concurrently with the swarms of LP events. Thereafter, swarms of local-tectonic (LT) and volcano-tectonic (VT) earthquakes started. We focus here on analyzing the LP events in the following manner. First, we estimate the source location of LP events by applying a 3-D non-linear hypocenter localization algorithm which includes topography. We then study the waveforms and spectral characteristics of LP events recorded at different stations and investigate whether or not these characteristics are due to source effects. Subsequently, we compute the oscillation frequencies (f) and the decay characteristics (Q factor) in the complex frequency domain of the coda part of the LP events by using the Sompi method which is based on a homogeneous auto-regressive (AR) equation. The rectangular fluid-filled crack model is used to estimate the physical processes related to the observed temporal variations in the complex frequencies. We divide the swarms of LP events into two intervals. The first interval occurred between June and July 2011 (48 LP events), while the second interval extended from september to October 2011 (36 LP events). The frequencies of LP events observed during these intervals range between 1.1 and 6.2 Hz while the Q factors are widely scattered between 20 and 400. We estimate the compositions of fluids inside the crack during both intervals as either water foam (mixtures of water and H2O gas/steam) or

  14. Fluid dynamics inside a "wet" volcano inferred from the complex frequencies of long-period (LP) events: An example from Papandayan volcano, West Java, Indonesia, during the 2011 seismic unrest

    NASA Astrophysics Data System (ADS)

    Syahbana, Devy Kamil; Caudron, Corentin; Jousset, Philippe; Lecocq, Thomas; Camelbeeck, Thierry; Bernard, Alain; Surono

    2014-06-01

    We present results of our study aimed at understanding the dynamics of fluids inside a "wet" volcano through the analysis of swarms of long-period (LP) events accompanying the 2011 seismic unrest at Papandayan volcano, West Java, Indonesia. Prior to this unrest, we measured an extremely high percentage (100 %) of CO2 in the ground at the summit crater, however with a very low value of SO2 flux (~ 6 tons/day). Increase in volcanic activity was also observed from the records of a tiltmeter. A long-term inflation was followed by an abrupt deflation that took place concurrently with the swarms of LP events. Thereafter, swarms of local-tectonic (LT) and volcano-tectonic (VT) earthquakes started. We focus here on analyzing the LP events in the following manner. First, we estimate the source location of LP events by applying a 3-D non-linear hypocenter localization algorithm which includes topography. We then study the waveforms and spectral characteristics of LP events recorded at different stations and investigate whether or not these characteristics are due to source effects. Subsequently, we compute the oscillation frequencies (f) and the decay characteristics (Q factor) in the complex frequency domain of the coda part of the LP events by using the Sompi method which is based on a homogeneous auto-regressive (AR) equation. The rectangular fluid-filled crack model is used to estimate the physical processes related to the observed temporal variations in the complex frequencies. We divide the swarms of LP events into two intervals. The first interval occurred between June and July 2011 (48 LP events), while the second interval extended from September to October 2011 (36 LP events). The frequencies of LP events observed during these intervals range between 1.1 and 6.2 Hz while the Q factors are widely scattered between 20 and 400. We estimate the compositions of fluids inside the crack during both intervals as either water foam (mixtures of water and H2O gas/steam) or

  15. Transient spatiotemporal chaos in reaction-diffusion networks

    NASA Astrophysics Data System (ADS)

    Wackerbauer, Renate

    2010-03-01

    Complex transient dynamics is reported in various extended systems, including transient turbulence in shear flows, transient spatiotemporal chaos in reaction- diffusion models, and non-chaotic irregular transient dynamics in neural networks. The asymptotic stability is difficult to determine since the transient lifetime typically increases exponentially with the system size. Our studies show that transient spatiotemporal chaos is extensive in various reaction- diffusion systems; the Lyapunov dimension increases linearly with the network size. A master stability analysis provides insight into the asymptotic stability in the Baer- Eiswirth and the Gray-Scott systems. The asymptotic state is characterized by negative transverse Lyapunov exponents on the attractor of the invariant synchronization manifold. The average lifetime depends on the number of transverse directions that are unstable along a typical excitation cycle.

  16. Transient Uncoupling Induces Synchronization

    NASA Astrophysics Data System (ADS)

    Schröder, Malte; Mannattil, Manu; Dutta, Debabrata; Chakraborty, Sagar; Timme, Marc

    2015-07-01

    Finding conditions that support synchronization is a fertile and active area of research with applications across multiple disciplines. Here we present and analyze a scheme for synchronizing chaotic dynamical systems by transiently uncoupling them. Specifically, systems coupled only in a fraction of their state space may synchronize even if fully coupled they do not. While for many standard systems coupling strengths need to be bounded to ensure synchrony, transient uncoupling removes this bound and thus enables synchronization in an infinite range of effective coupling strengths. The presented coupling scheme therefore opens up the possibility to induce synchrony in (biological or technical) systems whose parameters are fixed and cannot be modified continuously.

  17. Transient Uncoupling Induces Synchronization.

    PubMed

    Schröder, Malte; Mannattil, Manu; Dutta, Debabrata; Chakraborty, Sagar; Timme, Marc

    2015-07-31

    Finding conditions that support synchronization is a fertile and active area of research with applications across multiple disciplines. Here we present and analyze a scheme for synchronizing chaotic dynamical systems by transiently uncoupling them. Specifically, systems coupled only in a fraction of their state space may synchronize even if fully coupled they do not. While for many standard systems coupling strengths need to be bounded to ensure synchrony, transient uncoupling removes this bound and thus enables synchronization in an infinite range of effective coupling strengths. The presented coupling scheme therefore opens up the possibility to induce synchrony in (biological or technical) systems whose parameters are fixed and cannot be modified continuously. PMID:26274420

  18. Transient magnetic field signatures at high latitudes

    SciTech Connect

    Sibeck, D.G. )

    1993-01-01

    We survey GOES 2/5/6 geosynchronous and Huancayo, Peru, ground magnetometer observations at the times of 70 transient (2-10 min) events recorded at South Pole Station, Antarctica. The simultaneous observations indicate that most South Pole events correspond to sudden sharp variations in the equatorial magnetospheric and low-latitude ground magnetic field. The exceptions occur when the South Pole events have weak amplitudes and/or Huancayo and GOES 2/5/6 are far from local noon. The corresponding features observed at GOES 5 and GOES 6 are generally similar, with a lag indicating antisunward motion. A similar antisunward motion may be inferred from the ground observations themselves. On a case-by-case and statistical basis, the characteristics of the events observed in South Pole ground magnetograms resemble those previously interpreted as sudden impulse and sudden storm commencement signatures at other high-latitude stations. These observations suggest that the transient events at South Pole form part of the magnetospheric and ionospheric response to a sudden change in the fraction of the solar wind dynamic pressure applied to the magnetosphere. 57 refs., 14 figs.

  19. Observations of large transient magnetospheric electric fields

    NASA Technical Reports Server (NTRS)

    Aggson, T. L.; Heppner, J. P.

    1977-01-01

    Transient electric field events were observed with the long, double probe instrumentation carried by the IMP-6 satellite. Nine, clearly defined, exceptionally large amplitude events are presented here. The events are observed in the midnight sector at geocentric distances 3.5 to .5.5 R sub e at middle latitudes within a magnetic L-shell range of 4.8 to 7.5. They usually have a total duration of one to several minutes, with peak power spectra amplitudes occurring at a frequency of about 0.3 Hz. The events occur under magnetically disturbed conditions, and in most cases they can be associated with negative dH/dt excursions at magnetic observatories located near the foot of the magnetic field line intersecting IMP-6. The magnetospheric motions calculated for these electric fields indicated a quasi-stochastical diffusive process rather than the general inward magnetospheric collapsing motion expected during the expansive phases of auroral substorm activity.

  20. Radar observations of a tornado-spawning storm complex in Southeast Brazil and Meso-Eta forecasts of this extreme event

    NASA Astrophysics Data System (ADS)

    Held, Gerhard; Gomes, Jorge Luis; Gomes, Ana Maria

    2014-05-01

    During the early afternoon of 22 September 2013, severe storms, accompanied by large hail, damaging winds, heavy precipitation and intense lightning activity, devastated a region in the southeast State of São Paulo. Several extremely intense storm cells moved at up to 80 km/h east-southeastwards, ahead of a strong cold front approaching through Paraná, which created extremely unstable conditions that led to deep convection and overshooting towers up to 18 km. At least one of theses cells spawned a tornado when it reached the town of Taquarituba. The tornado traversed the town from south-southwest to north-northeast and was responsible for 63 people injured and two fatalities. Based on the damage reported, it was at least an F3 according to the Fujita scale. The objective of the present study is to characterize this severe thunderstorm event, using different types of data, and to evaluate the forecasts provided by the Meso-Eta model centered over Bauru. The pre-frontal and frontal convective cells were tracked throughout their life-time by IPMet's Doppler radars, which cover the western and central regions of the State São Paulo, as well as northern Paraná State. Radar volume scans, generated every 7,5 min, were processed with the TITAN (Thunderstorm Identification, Tracking, Analysis and Nowcasting) Software, yielding the following preliminary results: as the storm complex traversed the Paranapanema River, which forms the border between the two states, the cells intensified drastically and shortly before reaching the town of Taquarituba, that particular cell displayed extremely strong radial shear just above the cloud base (about -20 to +35 m/s), which led to the formation of a deep meso-cyclone, from which the tornado spawned and touched down at around 14:30 LT (LT=UT-3h). Cell properties calculated by TITAN showed a drastic increase of VIL (Vertically Integrated Liquid water content) from 13:52 LT (7,9 kg/m2) to a maximum of 61,8 kg/m2 at 14:15 LT. From 14

  1. Signature of transient boundary layer processes observed with Viking

    SciTech Connect

    Woch, J.; Lundin, R. )

    1992-02-01

    Transient penetration of plasma with magnetosheath origin is frequently observed with the hot plasma experiment on board the Viking satellite at auroral latitudes in the dayside magnetosphere. The injected magnetosheath ions exhibit a characteristic pitch angle/energy dispersion pattern earlier reported for solar wind ions accessing the magnetosphere in the cusp regions. In contrast to the continuous plasma entry in the cusp, the events discussed here show temporal features which suggest a connection to transient processes at or in the vicinity of the magnetospheric boundary. A single event study confirms previously published observations that the injected ions flow essentially tailward with a velocity comparable to the magnetosheath flow and that the energy spectra inferred for the source population resemble magnetosheath spectra. Based on a statistical study, it is found that these events are predominantly observed around 0800 and 1600 MLT, in a region populated by both rung current/plasma sheet particles and by particles whose source is the magnetosheath plasma. Magnetic field line tracing based on the Tsyganenko magnetic field model yields a scatter of the source locations around the mid-latitude region of the magnetospheric boundary. The probability for these events to occur is highest when the interplanetary magnetic field (IMF) is confined to the ecliptic plane. The connection of the events to transient impulsive solar wind/magnetosphere interaction processes, such as transient reconnection (FTE), impulsive plasma transfer, Kelvin Helmholtz instabilities, and solar wind pressure pulses, is discussed. A relation with transient reconnection can be excluded.

  2. Measuring Transient Memory Load

    ERIC Educational Resources Information Center

    Wanner, Eric; Shiner, Sandra

    1976-01-01

    Two experiments are reported in which subjects performed simple mental arithmetic problems which were presented visually in a sequential fashion. At some point in the presentation of each problem, the sequential display was interrupted and a memory task introduced. The purpose was to validate a measure of transient memory load. (Author/RM)

  3. Rotor transient analysis

    NASA Technical Reports Server (NTRS)

    Allaire, P. E.; Choy, K. C.; Gunter, E. J.

    1980-01-01

    Undamped modes approximate dynamic behavior of rotors and bearings. Application of modal analysis to uncouple equations of motion simplifies stability, steady-state unbalance response, and transient response analysis of system; nonlinear stability is predicted from calculated frequency spectra. Analysis provides designers with complete information without involving large-scale computational costs. Programs are written in FORTRAN IV for use on CDC 6600 computer.

  4. A new type of ion injection event observed by Viking

    SciTech Connect

    Yamauchi, M.; Lundin, R.; Woch, J. ); Shapshak, M. ); Elphinstone, R. )

    1993-05-07

    The authors report on the observation of a new type of ion injection event observed by Viking spacecraft several degrees equatorward of the cusp. Its signature seems considerably different than previously reported events such as flux transfer events or impulsive or transient magnetosheath plasma injection events. It consists of low energy ions, as the pattern drops sharply above 100 to 200 eV.

  5. Scrophularia arguta, a widespread annual plant in the Canary Islands: a single recent colonization event or a more complex phylogeographic pattern?

    PubMed

    Valtueña, Francisco Javier; López, Josefa; Álvarez, Juan; Rodríguez-Riaño, Tomás; Ortega-Olivencia, Ana

    2016-07-01

    Many studies have addressed evolution and phylogeography of plant taxa in oceanic islands, but have primarily focused on endemics because of the assumption that in widespread taxa the absence of morphological differentiation between island and mainland populations is due to recent colonization. In this paper, we studied the phylogeography of Scrophularia arguta, a widespread annual species, in an attempt to determine the number and spatiotemporal origins of dispersal events to Canary Islands. Four different regions, ITS and ETS from nDNA and psbA-trnH and psbJ-petA from cpDNA, were used to date divergence events within S. arguta lineages and determine the phylogenetic relationships among populations. A haplotype network was obtained to elucidate the phylogenetic relationships among haplotypes. Our results support an ancient origin of S. arguta (Miocene) with expansion and genetic differentiation in the Pliocene coinciding with the aridification of northern Africa and the formation of the Mediterranean climate. Indeed, results indicate for Canary Islands three different events of colonization, including two ancient events that probably happened in the Pliocene and have originated the genetically most divergent populations into this species and, interestingly, a recent third event of colonization of Gran Canaria from mainland instead from the closest islands (Tenerife or Fuerteventura). In spite of the great genetic divergence among populations, it has not implied any morphological variation. Our work highlights the importance of nonendemic species to the genetic richness and conservation of island flora and the significance of the island populations of widespread taxa in the global biodiversity. PMID:27386073

  6. Photonic nonlinear transient computing with multiple-delay wavelength dynamics.

    PubMed

    Martinenghi, Romain; Rybalko, Sergei; Jacquot, Maxime; Chembo, Yanne K; Larger, Laurent

    2012-06-15

    We report on the experimental demonstration of a hybrid optoelectronic neuromorphic computer based on a complex nonlinear wavelength dynamics including multiple delayed feedbacks with randomly defined weights. This neuromorphic approach is based on a new paradigm of a brain-inspired computational unit, intrinsically differing from Turing machines. This recent paradigm consists in expanding the input information to be processed into a higher dimensional phase space, through the nonlinear transient response of a complex dynamics excited by the input information. The computed output is then extracted via a linear separation of the transient trajectory in the complex phase space. The hyperplane separation is derived from a learning phase consisting of the resolution of a regression problem. The processing capability originates from the nonlinear transient, resulting in nonlinear transient computing. The computational performance is successfully evaluated on a standard benchmark test, namely, a spoken digit recognition task. PMID:23004274

  7. Photonic Nonlinear Transient Computing with Multiple-Delay Wavelength Dynamics

    NASA Astrophysics Data System (ADS)

    Martinenghi, Romain; Rybalko, Sergei; Jacquot, Maxime; Chembo, Yanne K.; Larger, Laurent

    2012-06-01

    We report on the experimental demonstration of a hybrid optoelectronic neuromorphic computer based on a complex nonlinear wavelength dynamics including multiple delayed feedbacks with randomly defined weights. This neuromorphic approach is based on a new paradigm of a brain-inspired computational unit, intrinsically differing from Turing machines. This recent paradigm consists in expanding the input information to be processed into a higher dimensional phase space, through the nonlinear transient response of a complex dynamics excited by the input information. The computed output is then extracted via a linear separation of the transient trajectory in the complex phase space. The hyperplane separation is derived from a learning phase consisting of the resolution of a regression problem. The processing capability originates from the nonlinear transient, resulting in nonlinear transient computing. The computational performance is successfully evaluated on a standard benchmark test, namely, a spoken digit recognition task.

  8. The Athena X-ray Observatory: observing luminous extragalactic transients

    NASA Astrophysics Data System (ADS)

    O'Brien, P. T.; Jonker, Peter G

    2014-08-01

    The ESA Athena X-ray observatory will combine exceptionally high throughout with high spectral-energy resolution. Athena will revolutionize many aspects of high-energy astrophysics. Here we concentrate on the subject of time-domain astronomy. Many of the most powerful transient sources, including gamma-ray bursts and tidal disruptions events, are bright X-ray sources. Athena will be designed to have a fast-response capability, permitting efficient observations of many transients. We will summarize the proposed capability of the mission and illustrate science programs to study transients ranging from the most distant GRBs to nuclear activity in nearby galaxies.

  9. Explorer for Transient Astrophysics: an X-ray transient mission for the 2020s

    NASA Astrophysics Data System (ADS)

    Camp, Jordan

    2016-04-01

    Explorer for Transient Astrophysics (ETA) is a wide-field X-ray transient mission proposed for flight starting in 2023. Through its unique imaging X-ray optics that allow a 30 deg by 20 deg FoV in three separate modules, a 1 arc min position resolution and a 10-11 erg/(sec cm2) sensitivity in 2000 sec, ETA will observe numerous events per year of X-ray transients related to compact objects, including: tidal disruptions of stars, supernova shock breakouts, neutron star bursts and superbursts, high redshift Gamma-Ray Bursts, and perhaps most exciting, X-ray counterparts of gravitational wave detections involving stellar mass and possibly supermassive black holes. The mission includes an IR Telescope that allows on-board redshift determination of gamma-ray bursts, and a small gamma-ray burst monitor to be contributed by the Technion (Israel Institute of Technology.)

  10. Transient and Variable Star Science with LSST

    NASA Astrophysics Data System (ADS)

    Walkowicz, Lucianne M.; Transients, LSST; Variable Stars Science Collaboration

    2011-01-01

    The time resolution and high etendue of LSST will revolutionize studies of a wide variety of astrophysical phenomena. The umbrella of time domain science with LSST encompasses objects both familiar and exotic, from classical variables within our Galaxy to explosive cosmological events. Within our Galaxy, LSST observations of variable stars will allow the mapping of the stellar halo in new detail, determination of the global Galactic cool star flare rate, and detection of rare evolved binary populations. Beyond the Milky Way, LSST will probe the distant Universe for the most luminous events. LSST will make localization for gravity wave events possible, identify counterparts to GRBs and X-ray flashes, and discover new supernovae. Increased sample sizes of known-but-rare observational phenomena will quantify their distributions for the first time, thus challenging existing theory. Perhaps most excitingly, LSST will provide the opportunity to sample previously untouched regions of parameter space, where transient events are expected on theoretical grounds, but have not yet been observed. In this talk, I will highlight some of the interesting scientific possibilities LSST will bring to transient and variable star science, as well as the challenges we face and opportunities for community involvement.

  11. Transient Microphonic Effects In Superconducting Cavities

    SciTech Connect

    Thomas Powers; G. Davis; Lawrence King

    2005-07-10

    A number of experiments were performed on an installed and operational 5-cell CEBAF cavity to determine the minimum time required to reestablish stable gradient after a cavity window arc trip. Once it was determined that gradient could be reestablished within 10 ms by applying constant power RF signal in and a voltage controlled Oscillator-phase locked loop based system (VCO-PLL), a second experiment was performed to determine if stable gradient could be reestablished using a fixed frequency RF system with a simple gradient based closed loop control system. During this test, instabilities were observed in the cavity forward power signal, which were determined to be microphonic in nature. These microphonic effects were quantified using a cavity resonance monitor and a VCO{_}PLL RF system. Two types of microphonic effects were observed depending on the type of arc event. If the arc occurred in the vacuum space between the warm and cold windows, the transient frequency shift was about 75 Hz peak-to-peak. If the arc occurred on the cavity side of the cold window the transient frequency shift was about 400 Hz peak-to-peak. The background microphonics level for the tested cavity was approximately 30 Hz peak-to-peak. Experimental results, analysis of the resultant klystron power transients, the decay time of the transients, and the implications with respect to fast reset algorithms will be presented.

  12. Transient neonatal zinc deficiency.

    PubMed

    Krieger, I; Alpern, B E; Cunnane, S C

    1986-06-01

    We report an infant who developed clinical manifestations of zinc deficiency during the first month of life although the diet was adequate for zinc and no other causes could be ascertained. The diagnosis was confirmed by low plasma-zinc concentrations and a positive response to zinc treatment. The fatty acid profile of plasma phospholipids was typical of zinc deficiency (ie, arachidonic acid was markedly decreased). The transient nature of this disorder was evident when no relapse occurred after cessation of zinc therapy and plasma-zinc and arachidonic acid concentrations remained normal. Several explanations for the development of transient neonatal zinc deficiency are offered. The observation demonstrates that occasional infants may have requirements for zinc that are beyond the intakes of the conventional RDA. PMID:3717070

  13. Transient infrared emission spectroscopy

    SciTech Connect

    Jones, R.W.; McClelland, J.F.

    1989-04-01

    Transient infrared emission spectroscopy (TIRES) is a new method that produces analytically useful emission spectra from optically thick, solid samples by greatly reducing self-absorption of emitted radiation. The method reduces self-absorption by creating a thin, short-lived, heated layer at the sample surface and collecting the transient emission from this layer. The technique requires no sample preparation and may be applied to both moving and stationary samples. The single-ended, noncontact TIRES measurement geometry is ideal for on-line and other remote-sensing applications. TIRES spectra acquired via a Fourier transform infrared spectrometer on moving samples of coal, plastic, and paint are presented and compared to photoacoustic absorption spectra of these materials. The TIRES and photoacoustic results are in close agreement as predicted by Kirchhoff's law.

  14. Event Perception

    PubMed Central

    Radvansky, Gabriel; Zacks, Jeffrey M.

    2012-01-01

    Events are central elements of human experience. Formally, they can be individuated in terms of the entities that compose them, the features of those entities, and the relations amongst entities. Psychologically, representations of events capture their spatiotemporal location, the people and objects involved, and the relations between these elements. Here, we present an account of the nature of psychological representations of events and how they are constructed and updated. Event representations are like images in that they are isomorphic to the situations they represent. However, they are like models or language in that they are constructed of components rather than being holistic. Also, they are partial representations that leave out some elements and abstract others. Representations of individual events are informed by schematic knowledge about general classes of events. Event representations are constructed in a process that segments continuous activity into discrete events. The construction of a series of event representations forms a basis for predicting the future, planning for that future, and imagining alternatives. PMID:23082236

  15. Two Transients discovered by PSST

    NASA Astrophysics Data System (ADS)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-08-01

    Two transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  16. Bright Transients discovered by PSST

    NASA Astrophysics Data System (ADS)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-08-01

    Six bright transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  17. Bright Transients discovered by PSST

    NASA Astrophysics Data System (ADS)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Denneau, L.; Stalder, B.; Heinze, A.; Sherstyuk, A.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-04-01

    Seven bright transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  18. The shape of dementia: new measures of morphological complexity in event-related potentials (ERP) and its application to the detection of Alzheimer's disease.

    PubMed

    Jimenez-Rodríguez, A; Rodríguez-Sotelo, J L; Osorio-Forero, A; Medina, J M; de Mejía, F Restrepo

    2015-09-01

    In this paper, we address the problem of quantifying the commonly observed disorganization of the stereotyped wave form of the ERP associated with the P300 component in patients with Alzheimer's disease. To that extent, we propose two new measures of complexity which relate the spectral content of the signal with its temporal waveform: the spectral matching coefficient and the spectral matching entropy. We show by means of experiments that those measures effectively measure complexity and are related to the shape in an intuitive way. Those indexes are compared with commonly used measures of complexity when comparing AD patients against age-matched healthy controls. The results indicate that AD ERP signals are, indeed, more complex in the shape than that of controls, and this result is evidenced mainly by means of our new measures which have a better performance compared to similar ones. Finally, we try to explain this increase in complexity in light of the communication through coherence hypothesis framework, relating commonly found changes in the EEG with our own results. PMID:25868458

  19. Advanced PFBC transient analysis

    SciTech Connect

    White, J.S.; Bonk, D.L.

    1997-05-01

    Transient modeling and analysis of advanced Pressurized Fluidized Bed Combustion (PFBC) systems is a research area that is currently under investigation by the US Department of Energy`s Federal Energy Technology Center (FETC). The object of the effort is to identify key operating parameters that affect plant performance and then quantify the basic response of major sub-systems to changes in operating conditions. PC-TRAX{trademark}, a commercially available dynamic software program, was chosen and applied in this modeling and analysis effort. This paper describes the development of a series of TRAX-based transient models of advanced PFBC power plants. These power plants burn coal or other suitable fuel in a PFBC, and the high temperature flue gas supports low-Btu fuel gas or natural gas combustion in a gas turbine topping combustor. When it is utilized, the low-Btu fuel gas is produced in a bubbling bed carbonizer. High temperature, high pressure combustion products exiting the topping combustor are expanded in a modified gas turbine to generate electrical power. Waste heat from the system is used to raise and superheat steam for a reheat steam turbine bottoming cycle that generates additional electrical power. Basic control/instrumentation models were developed and modeled in PC-TRAX and used to investigate off-design plant performance. System performance for various transient conditions and control philosophies was studied.

  20. Events during eucaryotic rRNA transcription initiation and elongation: Conversion from the closed to the open promoter complex requires nucleotide substrates

    SciTech Connect

    Bateman, E.; Paule, M.R.

    1988-05-01

    Chemical footprinting and topological analysis were carried out on the Acanthamoeba castellanii rRNA transcription initiation factor (TIF) and RNA polymerase I complexes with DNA during transcription initiation and elongation. The results show that the binding of TIF and polymerase to the promoter does not alter the supercoiling of the DNA template and the template does not become sensitive to modification by diethylpyro-carbonate, which can identify melted DNA regions. Thus, in contrast to bacterial RNA polymerase, the eucaryotic RNA polymerase I-promoter complex is in a closed configuration preceding addition of nucleotides in vitro. Initiation and 3'-O-methyl CTP-limited translocation by RNA polymerase I results in separation of the polymerase-TIF footprints, leaving the TIF footprint unaltered. In contrast, initiation and translocation result in a significant change in the conformation of the polymerase-DNA complex, culminating in an unwound DNA region of at least 10 base pairs.

  1. Dating Transient Heating Events in the Solar Protoplanetary Disk

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2012-11-01

    Chondrites contain millimeter- to centimeter-sized objects that formed as the Solar System was still forming, allowing cosmochemists to do hands-on astronomy. Using advanced, mass spectrometry techniques, James Connelly (University of Copenhagen, Denmark) and colleagues there and at the University of Hawaii and the Vernadsky Insitute for Geochemistry and Analytical Chemistry, Moscow, measured the abundances of lead and uranium isotopes in calcium-aluminum-rich inclusions (CAIs) in the CV carbonaceous chondrite Efremovka and chondrules in Allende (CV) and in the unequilibrated ordinary chondrite Northwest Africa 5697 to determine their absolute ages. The results show that CAIs formed 4567.30 ± 0.16 million years ago, suggesting that CAI formation occurred within a narrow time interval of about 160,000 years. Analyses of chondrules indicate that chondrule formation began during this time and continued for 2-3 million years. These time scales are consistent with astronomical observations of infant stars, leading Connelly and colleagues to suggest that CAIs and chondrules record processes common to the accretion disks surrounding young stars. This implies that cosmochemists studying these primitive, ancient objects in chondrites are studying typical products of star formation.

  2. A Note on Transients in the SRO and ASRO Long-Period Data

    USGS Publications Warehouse

    Peterson, Jon

    1982-01-01

    Data users have occasionally observed pulse-like transients in the long-period waveforms recorded at the Seismic Research Observatories (SRO) and at the Modified High-Gain Long-Period (ASRO) stations. In a recent paper, Dziewonski et al (1981) reported transients associated with earthquake signals record at some SRO stations, and the authors ascribed these transients to an unpredictable nonlinear system response. While some transients in the SRO and ASRO data are indeed generated by a nonlinear response (clipping), others are the result of linear processes. All event-associated transients are predictable in the sense that they are produced by large impulsive body-wave signals.

  3. Transient Dissolved Organic Carbon Through Soils

    NASA Astrophysics Data System (ADS)

    Mei, Y.; Hornberger, G. M.; Kaplan, L. A.; Newbold, J. D.; Aufdenkampe, A. K.; Tsang, Y.

    2009-12-01

    Dissolved organic carbon (DOC) is an important constituent of soil solution that plays a role in many chemical and biological processes in soils; it is also an important energy source for bacteria in the soil ecosystem. Hydrology has a significant control on the transport and fate of dissolved organic carbon in the soil but mechanisms that affect said transport are not well understood. In particular, dynamic information on DOC transport through forest soils on short time scales (one or two precipitation event) is lacking at present. DOC is a very complex mix of organic compounds. A key to quantifying DOC dynamics is to establish useful approximations for behavior of this complex mixture. Biodegradable dissolved organic carbon (BDOC) is an important part of DOC. It is reported that between 12 and 44% of DOC released from the forest floor can be decomposed in solutions by indigenous microbes. In our study, we considered how DOC, BDOC, and flow interact in soil columns. In-situ soil cores with two different lengths were installed under a mixed deciduous canopy. The effects of artificial rain on DOC and BDOC transport were examined by dripping nano pure water amended with bromide on the top of soil cores and sampling the water collected at the bottom of the cores for DOC and BDOC. We used plug-flow biofilm reactors to measure the BDOC concentration. It is likely that reduced rates of decomposition in dry soils will cause microbial products of DOC to accumulate; hence DOC concentration should be high at the first flush of rain and decline as the event proceeds. The experimental results show the expected pattern, that is, the first samples we collected always had the highest DOC and BDOC concentrations. The concentrations tend to decline through the simulated precipitation event. Application of a second “storm” forty minutes after the cessation of the first application of water resulted in effluent DOC concentration increasing a small amount initially and then

  4. Complex Predicates and Event Structure: An Integrated Analysis of Serial Verb Constructions in the Mabia Languages of West Africa. Working Papers in Linguistics No. 20.

    ERIC Educational Resources Information Center

    Bodomo, Adams B.

    An integrated analysis of the syntax and semantics of serial verb constructions (SVCs) in a group of West African languages is presented. With data from Dagaare and closest relatives, a structural definition for SVCs is developed (two or more lexical verbs that share grammatical categories within a clause), establishing SVCs as complex predicates.…

  5. Is there a signal transduction pathway that links events at the plasma membrane to the phosphorylation state of the mitochondrial pyruvate dehydrogenase complex?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Monoclonal antibodies against the E1a subunit were used to quantify the mitochondrial pyruvate dehydrogenase complex (mtPDC) by enzyme-linked immunosorbent assay (ELISA). Recombinant Arabidopsis thaliana pyruvate dehydrogenase (E1) was used to calibrate the ELISA. Antibodies against a synthetic ph...

  6. A New Look on Protein-Polyphenol Complexation during Honey Storage: Is This a Random or Organized Event with the Help of Dirigent-Like Proteins?

    PubMed Central

    Brudzynski, Katrina; Sjaarda, Calvin; Maldonado-Alvarez, Liset

    2013-01-01

    Honey storage initiates melanoidin formation that involves a cascade of seemingly unguided redox reactions between amino acids/proteins, reducing sugars and polyphenols. In the process, high molecular weight protein-polyphenol complexes are formed, but the mechanism involved remains unknown. The objective of this study was twofold: to determine quantitative and qualitative changes in proteins in honeys stored for prolonged times and in different temperatures and to relate these changes to the formation of protein-polyphenol complexes. Six -month storage decreased the protein content by 46.7% in all tested honeys (t-test, p<0.002) with the rapid reduction occurring during the first three month. The changes in protein levels coincided with alterations in molecular size and net charge of proteins on SDS –PAGE. Electro-blotted proteins reacted with a quinone-specific nitro blue tetrazolium (NBT) on nitrocellulose membranes indicating that quinones derived from oxidized polyphenols formed covalent bonds with proteins. Protein-polyphenol complexes isolated by size-exclusion chromatography differed in size and stoichiometry and fall into two categories: (a) high molecular weight complexes (230–180 kDa) enriched in proteins but possessing a limited reducing activity toward the NBT and (b) lower molecular size complexes (110–85 kDa) enriched in polyphenols but strongly reducing the dye. The variable stoichiometry suggest that the large, “protein-type” complexes were formed by protein cross-linking, while in the smaller, “polyphenol-type” complexes polyphenols were first polymerized prior to protein binding. Quinones preferentially bound a 31 kDa protein which, by the electrospray quadrupole time of flight mass spectrometry (ESI-Qtof-MS) analysis, showed homology to dirigent-like proteins known for assisting in radical coupling and polymerization of phenolic compounds. These findings provide a new look on protein-polyphenol interaction in honey where the

  7. Cytogenetic and symbiont analysis of five members of the B. dorsalis complex (Diptera, Tephritidae): no evidence of chromosomal or symbiont-based speciation events.

    PubMed

    Augustinos, Antonios A; Drosopoulou, Elena; Gariou-Papalexiou, Aggeliki; Asimakis, Elias D; Cáceres, Carlos; Tsiamis, George; Bourtzis, Kostas; Penelope Mavragani-Tsipidou; Zacharopoulou, Antigone

    2015-01-01

    The Bactrocera dorsalis species complex, currently comprising about 90 entities has received much attention. During the last decades, considerable effort has been devoted to delimiting the species of the complex. This information is of great importance for agriculture and world trade, since the complex harbours several pest species of major economic importance and other species that could evolve into global threats. Speciation in Diptera is usually accompanied by chromosomal rearrangements, particularly inversions that are assumed to reduce/eliminate gene flow. Other candidates currently receiving much attention regarding their possible involvement in speciation are reproductive symbionts, such as Wolbachia, Spiroplasma, Arsenophonus, Rickettsia and Cardinium. Such symbionts tend to spread quickly through natural populations and can cause a variety of phenotypes that promote pre-mating and/or post-mating isolation and, in addition, can affect the biology, physiology, ecology and evolution of their insect hosts in various ways. Considering all these aspects, we present: (a) a summary of the recently gained knowledge on the cytogenetics of five members of the Bactrocera dorsalis complex, namely Bactrocera dorsalis s.s., Bactrocera invadens, Bactrocera philippinensis, Bactrocera papayae and Bactrocera carambolae, supplemented by additional data from a Bactrocera dorsalis s.s. colony from China, as well as by a cytogenetic comparison between the dorsalis complex and the genetically close species, Bactrocera tryoni, and, (b) a reproductive symbiont screening of 18 different colonized populations of these five taxa. Our analysis did not reveal any chromosomal rearrangements that could differentiate among them. Moreover, screening for reproductive symbionts was negative for all colonies derived from different geographic origins and/or hosts. There are many different factors that can lead to speciation, and our data do not support chromosomal and/or symbiotic

  8. Cytogenetic and symbiont analysis of five members of the B. dorsalis complex (Diptera, Tephritidae): no evidence of chromosomal or symbiont-based speciation events

    PubMed Central

    Augustinos, Antonios A.; Drosopoulou, Elena; Gariou-Papalexiou, Aggeliki; Asimakis, Elias D.; Cáceres, Carlos; Tsiamis, George; Bourtzis, Kostas; Penelope Mavragani-Tsipidou; Zacharopoulou, Antigone

    2015-01-01

    Abstract The Bactrocera dorsalis species complex, currently comprising about 90 entities has received much attention. During the last decades, considerable effort has been devoted to delimiting the species of the complex. This information is of great importance for agriculture and world trade, since the complex harbours several pest species of major economic importance and other species that could evolve into global threats. Speciation in Diptera is usually accompanied by chromosomal rearrangements, particularly inversions that are assumed to reduce/eliminate gene flow. Other candidates currently receiving much attention regarding their possible involvement in speciation are reproductive symbionts, such as Wolbachia, Spiroplasma, Arsenophonus, Rickettsia and Cardinium. Such symbionts tend to spread quickly through natural populations and can cause a variety of phenotypes that promote pre-mating and/or post-mating isolation and, in addition, can affect the biology, physiology, ecology and evolution of their insect hosts in various ways. Considering all these aspects, we present: (a) a summary of the recently gained knowledge on the cytogenetics of five members of the Bactrocera dorsalis complex, namely Bactrocera dorsalis s.s., Bactrocera invadens, Bactrocera philippinensis, Bactrocera papayae and Bactrocera carambolae, supplemented by additional data from a Bactrocera dorsalis s.s. colony from China, as well as by a cytogenetic comparison between the dorsalis complex and the genetically close species, Bactrocera tryoni, and, (b) a reproductive symbiont screening of 18 different colonized populations of these five taxa. Our analysis did not reveal any chromosomal rearrangements that could differentiate among them. Moreover, screening for reproductive symbionts was negative for all colonies derived from different geographic origins and/or hosts. There are many different factors that can lead to speciation, and our data do not support chromosomal and/or symbiotic

  9. Organization of extratropical transients during El Nino

    SciTech Connect

    Hoerling, M.P. ); Ting, Mingfang )

    1994-05-01

    Four observed El Nino-Southern Oscillation (ENSO) events are studied to determine the mechanisms responsible for the anomalous extratropical atmospheric circulation during northern winter. A parallel analysis of a GCM's response to El Nino is performed in order to assess if similar mechanisms are operative in the model atmosphere. The observed stationary wave anomalies over the Pacific/North American (PNA) region are found to be similar during the four winters despite appreciable differences in sea surface temperatures. The anomalous transient vorticity fluxes are remarkably robust over the North Pacific during each even, with an eastward extension of the climatological storm track leading to strong cyclonic forcing near 40[degrees]N, 150[degrees]W. This forcing is in phase with the seasonal mean Aleutian trough anomaly suggesting the important of eddy-mean flow interaction. By comparison, the intersample variability of the GCM response over the PNA region is found to exceed the observed inter-El Nino variability. This stems primarily from a large variability in the model's anomalous transients over the North Pacific. Further analysis reveals that extratropical vorticity transients are the primary mechanism maintaining the stationary wave anomalies over the PNA region during all four observed ENSO winters. In the case of the GCM, the organization of transient eddies is ill defined over the North Pacific, a behavior indicative of model error. A physical model is proposed to explain the robustness of the tropical controlling influence of the extratropical transients in nature. A simple equatorial Pacific heat source directly forces a tropical anticyclone whose phase relative to the climatological tropical anticyclone leads to an eastward extension of the subtropical jet stream. This mechanism appears to be equally effective for a heat source located either in the central or eastern Pacific basin. 36 refs., 14 figs.

  10. Fixation, transient landscape, and diffusion dilemma in stochastic evolutionary game dynamics

    NASA Astrophysics Data System (ADS)

    Zhou, Da; Qian, Hong

    2011-09-01

    Agent-based stochastic models for finite populations have recently received much attention in the game theory of evolutionary dynamics. Both the ultimate fixation and the pre-fixation transient behavior are important to a full understanding of the dynamics. In this paper, we study the transient dynamics of the well-mixed Moran process through constructing a landscape function. It is shown that the landscape playing a central theoretical “device” that integrates several lines of inquiries: the stable behavior of the replicator dynamics, the long-time fixation, and continuous diffusion approximation associated with asymptotically large population. Several issues relating to the transient dynamics are discussed: (i) multiple time scales phenomenon associated with intra- and inter-attractoral dynamics; (ii) discontinuous transition in stochastically stationary process akin to Maxwell construction in equilibrium statistical physics; and (iii) the dilemma diffusion approximation facing as a continuous approximation of the discrete evolutionary dynamics. It is found that rare events with exponentially small probabilities, corresponding to the uphill movements and barrier crossing in the landscape with multiple wells that are made possible by strong nonlinear dynamics, plays an important role in understanding the origin of the complexity in evolutionary, nonlinear biological systems.

  11. Workshop on Radio Transients

    NASA Astrophysics Data System (ADS)

    Croft, Steve; Gaensler, Bryan

    2012-04-01

    abstract-type="normal">SummaryWe are entering a new era in the study of variable and transient radio sources. This workshop discussed the instruments and the strategies employed to study those sources, how they are identified and classified, how results from different surveys can be compared, and how radio observations tie in with those at other wavelengths. The emphasis was on learning what common ground there is between the plethora of on-going projects, how methods and code can be shared, and how best practices regarding survey strategy could be adopted. The workshop featured the four topics below. Each topic commenced with a fairly brief introductory talk, which then developed into discussion. By way of preparation, participants had been invited to upload and discuss one slide per topic to a wiki ahead of the workshop. 1. Telescopes, instrumentation and survey strategy. New radio facilities and on-going projects (including upgrades) are both studying the variability of the radio sky, and searching for transients. The discussion first centred on the status of those facilities, and on projects with a time-domain focus, both ongoing and planned, before turning to factors driving choices of instrumentation, such as phased array versus single pixel feeds, the field of view, spatial and time resolution, frequency and bandwidth, depth, area, and cadence of the surveys. 2. Detection, pipelines, and classification. The workshop debated (a) the factors that influence decisions to study variability in the (u,v) plane, in images, or in catalogues, (b) whether, and how much, pipeline code could potentially be shared between one project and another, and which software packages are best for different approaches, (c) how data are stored and later accessed, and (d) how transients and variables are defined and classified. 3. Statistics, interpretation, and synthesis. It then discussed how (i) the choice of facility and strategy and (ii) detection and classification schemes

  12. Thermal transient anemometer

    DOEpatents

    Bailey, J.L.; Vresk, J.

    1989-07-18

    A thermal transient anemometer is disclosed having a thermocouple probe which is utilized to measure the change in temperature over a period of time to provide a measure of fluid flow velocity. The thermocouple probe is located in the fluid flow path and pulsed to heat or cool the probe. The cooling of the heated probe or the heating of the cooled probe from the fluid flow over a period of time is measured to determine the fluid flow velocity. The probe is desired to be locally heated near the tip to increase the efficiency of devices incorporating the probe. 12 figs.

  13. Thermal transient anemometer

    DOEpatents

    Bailey, James L.; Vresk, Josip

    1989-01-01

    A thermal transient anemometer having a thermocouple probe which is utilized to measure the change in temperature over a period of time to provide a measure of fluid flow velocity. The thermocouple probe is located in the fluid flow path and pulsed to heat or cool the probe. The cooling of the heated probe or the heating of the cooled probe from the fluid flow over a period of time is measured to determine the fluid flow velocity. The probe is desired to be locally heated near the tip to increase the efficiency of devices incorporating the probe.

  14. The Rapid Transient Surveyor

    NASA Astrophysics Data System (ADS)

    Baranec, Christoph; Tonry, John; Wright, Shelley; Tully, R. Brent; Lu, Jessica R.; Takamiya, Marianne Y.; Hunter, Lisa

    2016-01-01

    The next decade of astronomy will be dominated by large area surveys (see the detailed discussion in the Astro-2010 Decadal survey and NRC's recent OIR System Report). Ground-based optical transient surveys, e.g., LSST, ZTF and ATLAS and space-based exoplanet, supernova, and lensing surveys such as TESS and WFIRST will join the Gaia all-sky astrometric survey in producing a flood of data that will enable leaps in our understanding of the universe. There is a critical need for further characterization of these discoveries through high angular resolution images, deeper images, spectra, or observations at different cadences or periods than the main surveys. Such follow-up characterization must be well matched to the particular surveys, and requires sufficient additional observing resources and time to cover the extensive number of targets.We describe plans for the Rapid Transient Surveyor (RTS), a permanently mounted, rapid-response, high-cadence facility for follow-up characterization of transient objects on the U. of Hawai'i 2.2-m telescope on Maunakea. RTS will comprise an improved robotic laser adaptive optics system, based on the prototype Robo-AO system (formerly at the Palomar 1.5-m and now at the Kitt Peak 2.2-m telescope), with simultaneous visible and near-infrared imagers as well as a near-infrared integral field spectrograph (R~100, λ = 850 - 1830 nm, 0.15″ spaxels, 8.7″×6.0″ FoV). RTS will achieve an acuity of ~0.07″ in visible wavelengths and < 0.16″ in the near infrared leading to an increase of the infrared point-source sensitivity against the sky background by a factor of ~9, crucial for efficient near-infrared spectroscopy.RTS will allow us to map the dark matter distribution in the z < 0.1 local universe with ten times better accuracy and precision than previous experiments. ATLAS will discover several thousand SNIae per year, measuring SNIa peak brightness, and decline rates, while RTS will measure reddening by dust, confirm SN type and

  15. Viral Transmission Dynamics at Single-Cell Resolution Reveal Transiently Immune Subpopulations Caused by a Carrier State Association

    PubMed Central

    Cenens, William; Makumi, Angela; Govers, Sander K.; Lavigne, Rob; Aertsen, Abram

    2015-01-01

    Monitoring the complex transmission dynamics of a bacterial virus (temperate phage P22) throughout a population of its host (Salmonella Typhimurium) at single cell resolution revealed the unexpected existence of a transiently immune subpopulation of host cells that emerged from peculiarities preceding the process of lysogenization. More specifically, an infection event ultimately leading to a lysogen first yielded a phage carrier cell harboring a polarly tethered P22 episome. Upon subsequent division, the daughter cell inheriting this episome became lysogenized by an integration event yielding a prophage, while the other daughter cell became P22-free. However, since the phage carrier cell was shown to overproduce immunity factors that are cytoplasmically inherited by the P22-free daughter cell and further passed down to its siblings, a transiently resistant subpopulation was generated that upon dilution of these immunity factors again became susceptible to P22 infection. The iterative emergence and infection of transiently resistant subpopulations suggests a new bet-hedging strategy by which viruses could manage to sustain both vertical and horizontal transmission routes throughout an infected population without compromising a stable co-existence with their host. PMID:26720743

  16. Measurand transient signal suppressor

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    A transient signal suppressor for use in a controls system which is adapted to respond to a change in a physical parameter whenever it crosses a predetermined threshold value in a selected direction of increasing or decreasing values with respect to the threshold value and is sustained for a selected discrete time interval is presented. The suppressor includes a sensor transducer for sensing the physical parameter and generating an electrical input signal whenever the sensed physical parameter crosses the threshold level in the selected direction. A manually operated switch is provided for adapting the suppressor to produce an output drive signal whenever the physical parameter crosses the threshold value in the selected direction of increasing or decreasing values. A time delay circuit is selectively adjustable for suppressing the transducer input signal for a preselected one of a plurality of available discrete suppression time and producing an output signal only if the input signal is sustained for a time greater than the selected suppression time. An electronic gate is coupled to receive the transducer input signal and the timer output signal and produce an output drive signal for energizing a control relay whenever the transducer input is a non-transient signal which is sustained beyond the selected time interval.

  17. Characterizing Nanoscale Transient Communication.

    PubMed

    Chen, Yifan; Anwar, Putri Santi; Huang, Limin; Asvial, Muhamad

    2016-04-01

    We consider the novel paradigm of nanoscale transient communication (NTC), where certain components of the small-scale communication link are physically transient. As such, the transmitter and the receiver may change their properties over a prescribed lifespan due to their time-varying structures. The NTC systems may find important applications in the biomedical, environmental, and military fields, where system degradability allows for benign integration into life and environment. In this paper, we analyze the NTC systems from the channel-modeling and capacity-analysis perspectives and focus on the stochastically meaningful slow transience scenario, where the coherence time of degeneration Td is much longer than the coding delay Tc. We first develop novel and parsimonious models to characterize the NTC channels, where three types of physical layers are considered: electromagnetism-based terahertz (THz) communication, diffusion-based molecular communication (DMC), and nanobots-assisted touchable communication (TouchCom). We then revisit the classical performance measure of ϵ-outage channel capacity and take a fresh look at its formulations in the NTC context. Next, we present the notion of capacity degeneration profile (CDP), which describes the reduction of channel capacity with respect to the degeneration time. Finally, we provide numerical examples to demonstrate the features of CDP. To the best of our knowledge, the current work represents a first attempt to systematically evaluate the quality of nanoscale communication systems deteriorating with time. PMID:26955048

  18. An Improved Network Strain Filter for Detecting Transient Deformation Signals

    NASA Astrophysics Data System (ADS)

    Ohtani, R.; McGuire, J.; Segall, P.

    2008-12-01

    We have developed a tool to detect transient signals such as aseismic fault slip and magmatic intrusion automatically from large-scale (principally GPS) geodetic arrays, referred to as a Network Strain Filter (NSF). The NSF is capable of detecting transient signals in large data sets which may be difficult to identify by visual inspection of individual time series. The underlying principle is to exploit the spatially coherent nature of tectonic signals. The NSF models GPS displacement time series as a sum of contributions from tectonic transients, steady motion due to secular deformation, site-specific local benchmark motion, reference frame errors, and white noise. Transient deformation is represented by a spatial wavelet basis with time varying coefficients estimated using Kalman filtering techniques. A "hyperparameter" is also estimated to constrain the amount of temporal smoothness of the tectonic deformation. As station distribution is irregular and wavelets have local support (non-zero only over a localized domain), the design matrix is generally ill-conditioned. We investigate two strategies for regularizing the problem. The first is explicit spatial smoothing of the transient deformation. The second is to simply exclude wavelet bases that don't span some minimum number of stations. In this case, the smallest wavelet scale is determined such that the residual variance is consistent with the a priori errors of the data. Similarly the degree of spatial smoothing is determined by a priori knowledge of the data errors. To test the performance of the NSF, we carried out numerical tests using the southern California Integrated GPS Network (SCIGN) station distribution with synthetic transients of variable signal to noise ratio. We tested a six-year-long time series with a slow slip event with a duration of three years. Due to the long duration of the transient event, the contributions from secular motion and benchmark wobble make it difficult to identify the

  19. Transient upset models in computer systems

    NASA Technical Reports Server (NTRS)

    Mason, G. M.

    1983-01-01

    Essential factors for the design of transient upset monitors for computers are discussed. The upset is a system level event that is software dependent. It can occur in the program flow, the opcode set, the opcode address domain, the read address domain, and the write address domain. Most upsets are in the program flow. It is shown that simple, external monitors functioning transparently relative to the system operations can be built if a detailed accounting is made of the characteristics of the faults that can happen. Sample applications are provided for different states of the Z-80 and 8085 based system.

  20. Transient global amnesia during transoesophageal echocardiogram.

    PubMed

    Profice, Paolo; Rizzello, Vittoria; Pennestrì, Faustino; Pilato, Fabio; Della Marca, Giacomo; Sestito, Alfonso; Crea, Filippo; Tonali, Pietro A; Di Lazzaro, Vincenzo

    2008-12-01

    Transient global amnesia (TGA) is a common paroxysmal disorder of episodic memory. The aetiology of TGA is still unknown. Brain ischaemia, migraine, epileptic seizure, venous congestion and psychological disturbances have been proposed as pathological mechanisms. Moreover, different precipitating events are recognised in most TGA patients including physical activity, severe emotional stress, painful experiences, immersion in cold water and sexual intercourse. We describe a 54-year-old woman who presented a TGA immediately after right-left shunt of saline contrast during the execution of transoesophageal echocardiography. Aetiopathological considerations for this uncommon presentation are discussed. PMID:19031042

  1. Blade loss transient dynamic analysis of turbomachinery

    NASA Technical Reports Server (NTRS)

    Stallone, M. J.; Gallardo, V.; Storace, A. F.; Bach, L. J.; Black, G.; Gaffney, E. F.

    1982-01-01

    This paper reports on work completed to develop an analytical method for predicting the transient non-linear response of a complete aircraft engine system due to the loss of a fan blade, and to validate the analysis by comparing the results against actual blade loss test data. The solution, which is based on the component element method, accounts for rotor-to-casing rubs, high damping and rapid deceleration rates associated with the blade loss event. A comparison of test results and predicted response show good agreement except for an initial overshoot spike not observed in test. The method is effective for analysis of large systems.

  2. Real-time detection of optical transients with RAPTOR

    SciTech Connect

    Borozdin, K. N.; Brumby, Steven P.; Galassi, M. C.; McGowan, K. E.; Starr, D. L.; Vestrand, W. T.; White, R. R.; Wozniak, P. R.; Wren, J.

    2002-01-01

    Fast variability of optical objects is an interesting though poorly explored subject in modern astronomy. Real-time data processing and identification of transient, celestial events in the images is very important, for such study as it allows rapid follow-up with more sensitive instruments, We discuss an approach which we have chosen for the RAPTOR project which is a pioneering close-loop system combining real-time transient detection with rapid follow-up. Our data processing pipeline is able to identify and localize an optical transient within seconds after the observation. We describe the challenges we met, solutions we found and some results obtained in our search for fast optical transients. The software pipeline we have developed for RAPTOR can easily be applied to the data from other experiments.

  3. Real-Time Detection of Optical Transients with RAPTOR

    NASA Astrophysics Data System (ADS)

    Borozdin, Konstantin N.; Brumby, Steven P.; Galassi, Mark C.; McGowan, Katherine; Starr, Daniel; Vestrand, Thomas; White, Robert; Wozniak, Przemek; Wren, James A.

    2002-12-01

    Fast variability of optical objects is an interesting though poorly explored subject in modern astronomy. Real-time data processing and identification of transient celestial events in the images is very important for such study as it allows rapid follow-up with more sensitive instruments. We discuss an approach which we have developed for the RAPTOR project, a pioneering closed-loop system combining real-time transient detection with rapid follow-up. RAPTOR's data processing pipeline is able to identify and localize an optical transient within seconds after the observation. The testing we performed so far have been confirming the effectiveness of our method for the optical transient detection. The software pipeline we have developed for RAPTOR can easily be applied to the data from other experiments.

  4. 2.1-1.85 Ga tectonic events in the Yangtze Block, South China: Petrological and geochronological evidence from the Kongling Complex and implications for the reconstruction of supercontinent Columbia

    NASA Astrophysics Data System (ADS)

    Yin, Changqing; Lin, Shoufa; Davis, Donald W.; Zhao, Guochun; Xiao, Wenjiao; Li, Longming; He, Yanhong

    2013-12-01

    This paper presents petrography, zircon U-Pb ages and Hf isotopic data as well as whole-rock Sm-Nd isotopic data for mafic granulites, metapelitic rocks and high-grade marble from the Kongling Complex in the Yangtze Block, South China. Petrographic observations indicate that these three types of rocks experienced high-pressure metamorphism. Their mineral assemblages and P-T conditions define a clockwise P-T path involving isothermal decompression following the peak high-pressure metamorphism, which is considered to record a continent-continent collisional event. This is systematic documentation of the tectonic evolution of the Kongling Complex from 2.1-2.0 Ga deposition (constrained by youngest detrital zircon and metamorphic zircon) through ~ 2.0 Ga collision (high-pressure metamorphism) and syn-collisional partial melting (S-type granite and migmatization of TTG gneiss) to ~ 1.85 Ga post-collisional extension (A-type high-K granite and mafic dyke). These ages are broadly coincident with global collisional events (2.1-1.8 Ga) that led to the assembly of the Palaeo-Mesoproterozoic Columbia (or Nuna) supercontinent. Therefore, this study provides strong evidence that the Yangtze Block in South China was a component of the Columbia supercontinent.

  5. The joy of transient chaos

    SciTech Connect

    Tél, Tamás

    2015-09-15

    We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

  6. Multiscale Transient Signal Detection: Localizing Transients in Geodetic Data Through Wavelet Transforms and Sparse Estimation Techniques

    NASA Astrophysics Data System (ADS)

    Riel, B.; Simons, M.; Agram, P.

    2012-12-01

    Transients are a class of deformation signals on the Earth's surface that can be described as non-periodic accumulation of strain in the crust. Over seismically and volcanically active regions, these signals are often challenging to detect due to noise and other modes of deformation. Geodetic datasets that provide precise measurements of surface displacement over wide areas are ideal for exploiting both the spatial and temporal coherence of transient signals. We present an extension to the Multiscale InSAR Time Series (MInTS) approach for analyzing geodetic data by combining the localization benefits of wavelet transforms (localizing signals in space) with sparse optimization techniques (localizing signals in time). Our time parameterization approach allows us to reduce geodetic time series to sparse, compressible signals with very few non-zero coefficients corresponding to transient events. We first demonstrate the temporal transient detection by analyzing GPS data over the Long Valley caldera in California and along the San Andreas fault near Parkfield, CA. For Long Valley, we are able to resolve the documented 2002-2003 uplift event with greater temporal precision. Similarly for Parkfield, we model the postseismic deformation by specific integrated basis splines characterized by timescales that are largely consistent with postseismic relaxation times. We then apply our method to ERS and Envisat InSAR datasets consisting of over 200 interferograms for Long Valley and over 100 interferograms for Parkfield. The wavelet transforms reduce the impact of spatially correlated atmospheric noise common in InSAR data since the wavelet coefficients themselves are essentially uncorrelated. The spatial density and extended temporal coverage of the InSAR data allows us to effectively localize ground deformation events in both space and time with greater precision than has been previously accomplished.

  7. The Zwicky Transient Facility

    NASA Astrophysics Data System (ADS)

    Kulkarni, Shrinivas R.

    2016-01-01

    The Zwicky Transient Facility (ZTF) has been designed with a singular focus: a systematic exploration of the night sky at a magnitude level well suited for spectral classification and follow up with the existing class of 4-m to 10-m class telescopes. ZTF is the successor to the Palomar Transient Factory (PTF). The discovery engine for ZTF is a 47 square degree camera (realized through 16 e2V monolithic CCDs) that fills the entire focal plane of the 48-inch Oschin telescope of the Palomar Observatory. Single 30-s epoch sensitivity is about 20.5 in g and R bands. The Infarared Processing & Analysis Center (IPAC) is the data center for ZTF. ZTF is a public-private partnership with equal contributions from a consortium of world-wide partners and an NSF MSIP grant. Forty percent of ZTF time is set aside for two major community surveys: a 3-day cadence survey of high latitudes (to mimic LSST) and a time domain survey of the entire Northern Galactic plane. We expect first light in February 2017 and begin a 3-year survey starting summer of 2017. The first year will be spent on building up deep reference images of the sky (a must for transient surveys). During the second year IPAC will deliver near archival quality photometric products within 12 hours of observations. By comparison to reference images photometric alerts will be sent out. Year 3 will see the near real-time release of image differencing products. A Community Science Advisory Committee (CSAC), chaired by S. Ridgway (NOAO), has been set up to both advise the PI and to ensure that the US community's interests are well served. Astronomers interested in getting a head start on ZTF may wish to peruse the data releases from PTF. Young people (or young at heart) may wish to attend the annual summer school on PTF/ZTF (August, Caltech campus). The Principal Investigator (PI) for the project is S. Kulkarni and the Project Scientist is Eric Bellm.For further details please consult http://www.ptf.caltech.edu/ztf

  8. Remarks on Muscle Contraction Mechanism II. Isometric Tension Transient and Isotonic Velocity Transient

    PubMed Central

    Mitsui, Toshio; Takai, Nobukatsu; Ohshima, Hiroyuki

    2011-01-01

    Mitsui and Ohshima (2008) criticized the power-stroke model for muscle contraction and proposed a new model. In the new model, about 41% of the myosin heads are bound to actin filaments, and each bound head forms a complex MA3 with three actin molecules A1, A2 and A3 forming the crossbridge. The complex translates along the actin filament cooperating with each other. The new model well explained the experimental data on the steady filament sliding. As an extension of the study, the isometric tension transient and isotonic velocity transient are investigated. Statistical ensemble of crossbridges is introduced, and variation of the binding probability of myosin head to A1 is considered. When the binding probability to A1 is zero, the Hill-type force-velocity relation is resulted in. When the binding probability to A1 becomes finite, the deviation from the Hill-type force-velocity relation takes place, as observed by Edman (1988). The characteristics of the isometric tension transient observed by Ford, Huxley and Simmons (1977) and of the isotonic velocity transient observed by Civan and Podolsky (1966) are theoretically reproduced. Ratios of the extensibility are estimated as 0.22 for the crossbridge, 0.26 for the myosin filament and 0.52 for the actin filament, in consistency with the values determined by X-ray diffraction by Wakabayashi et al. (1994). PMID:21673917

  9. Loss of expression of the SWI/SNF complex is a frequent event in undifferentiated/dedifferentiated urothelial carcinoma of the urinary tract.

    PubMed

    Agaimy, Abbas; Bertz, Simone; Cheng, Liang; Hes, Ondrej; Junker, Kerstin; Keck, Bastian; Lopez-Beltran, Antonio; Stöckle, Michael; Wullich, Bernd; Hartmann, Arndt

    2016-09-01

    Loss of the SWI/SNF chromatin remodeling complex has been recently implicated in the pathogenesis of dedifferentiated carcinomas from different organs, but its possible role in undifferentiated urothelial carcinoma (UC) has not been studied to date. In this study, we analyzed by immunohistochemistry 14 undifferentiated UCs (11 from bladder and 3 from renal pelvis) with a nondescript anaplastic or rhabdoid morphology, using commercially available antibodies against the SWI/SNF components SMARCB1 (INI1), SMARCA2, SMARCA4, SMARCC1, SMARCC2, and ARID1A. Patients were eight females and six males aged 40 to 84 years (median, 65). All tumors were muscle-invasive (9 were T3-4). A conventional UC component was seen in eight cases and varied from in situ to papillary. The undifferentiated component comprised 60-100 % of the tumors. Histologically, most tumors showed diffuse dyscohesive or pseudoalveolar growth of variably sized cells with frequent rhabdoid features. Transition from conventional to undifferentiated UC was abrupt, except in one case. The undifferentiated component almost always expressed pan-cytokeratin AE1/AE3 (13/14) and variably vimentin (8/14) and GATA3 (9/14). Complete loss of at least one SWI/SNF subunit limited to the undifferentiated component was detected in 10/14 cases (71 %). SMARCA2 was most frequently lost (six) followed by ARID1A (four), SMARCB1/INI1 (two), SMARCA4 (one), and SMARCC1 (one). This is the first study exploring SWI/SNF expression in undifferentiated UC of the urinary tract. Our results are in line with recent studies reporting involvement of the SWI/SNF complex in the dedifferentiation process of a variety of epithelial neoplasms in different organs, including the urinary tract, and association with aggressive clinical course. PMID:27339451

  10. Optical transient monitor

    NASA Astrophysics Data System (ADS)

    Bernas, Martin; Páta, Petr; Hudec, René; Soldán, Jan; Rezek, Tomáš; Castro-Tirado, Alberto J.

    1998-05-01

    Although there are several optical GRB follow-up systems in operation and/or in development, some of them with a very short response time, they will never be able to provide true simultaneous (no delay) and pre-burst optical data for GRBs. We report on the development and tests of a monitoring experiment expected to be put into test operation in 1998. The system should detect Optical Transients down to mag 6-7 (few seconds duration assumed) over a wide field of view. The system is based on the double CCD wide-field cameras ST8. For the real time evaluation of the signal from both cameras, two TMS 320C40 processors are used. Using two channels differing in spectral sensitivity and processing of temporal sequence of images allows us to eliminate man-made objects and defects of the CCD electronics. The system is controlled by a standard PC computer.

  11. Transient Dentritic Solidification Experiment

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Transient Dentritic Solidification Experiment (TDSE) is being developed as a candidate for flight aboard the International Space Station. TDSE will study the growth of dentrites (treelike crystalline structures) in a transparent material (succinonitrile or SCN) that mimics the behavior of widely used iron-based metals. Basic work by three Space Shuttle flights (STS-62, STS-75, and STS-87) of the Isothermal Dendritic Growth Experiment (IDGE) is yielding new insights into virtually all industrially relevant metal and alloy forming operations. The TDSE is similar to IDGE, but will maintain a constant temperature while varying pressure on the dentrites. Shown here is a cutaway of the isothermal bath containing its growth cell at the heart of the TDSE. The principal investigator is Matthew Koss of College of the Holy Cross in Worcester, MA. Note: an Acrobat PDF version is available from http://microgravity.nasa.gov/gallery

  12. Transient heliosheath modulation

    NASA Astrophysics Data System (ADS)

    Quenby, J. J.; Webber, W. R.

    2015-10-01

    Voyager 1 has explored the solar wind-interstellar medium interaction region between the terminal shock and heliopause, following the intensity distribution of Galactic cosmic ray protons above 200 MeV energy. Before this component reached the expected galactic flux level at 121.7 au from the Sun, four episodes of rapid intensity change occurred with a behaviour similar to that found in Forbush Decreases in the inner Solar system, rather than that expected from a mechanism related to models for the long-term modulation found closer to the Sun. Because the mean solar wind flow is both expected and observed to be perpendicular to the radial direction close to the heliopause, an explanation is suggested in terms of transient radial flows related to possible heliopause boundary flapping. It is necessary that the radial flows are of the order either of the sound speed found for conditions downstream of the terminal shock or of the fluctuations found near the boundary by the Voyager 1 Low Energy Charged Particle detector and that the relevant cosmic ray diffusion perpendicular to the mean field is controlled by `slab' fluctuations accounting for about 20 per cent of the total power in the field variance. However, additional radial drift motion related to possible north to south gradients in the magnetic field may allow the inclusion of some diffusion according to the predictions of a theory based upon the presence of 2D turbulence. The required field gradients may arise due to field variation in the field carried by solar plasma flow deflected away from the solar equatorial plane. Modulation amounting to a total 30 per cent drop in galactic intensity requires explanation by a combination of transient effects.

  13. Aeroelastic Modeling of a Nozzle Startup Transient

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Zhao, Xiang; Zhang, Sijun; Chen, Yen-Sen

    2014-01-01

    Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading to structural damages if structural strengthening measures were not taken. The modeling picture is incomplete without the capability to address the two-way responses between the structure and fluid. The objective of this study is to develop a tightly coupled aeroelastic modeling algorithm by implementing the necessary structural dynamics component into an anchored computational fluid dynamics methodology. The computational fluid dynamics component is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, while the computational structural dynamics component is developed under the framework of modal analysis. Transient aeroelastic nozzle startup analyses at sea level were performed, and the computed transient nozzle fluid-structure interaction physics presented,

  14. Transient absolute robustness in stochastic biochemical networks.

    PubMed

    Enciso, German A

    2016-08-01

    Absolute robustness allows biochemical networks to sustain a consistent steady-state output in the face of protein concentration variability from cell to cell. This property is structural and can be determined from the topology of the network alone regardless of rate parameters. An important question regarding these systems is the effect of discrete biochemical noise in the dynamical behaviour. In this paper, a variable freezing technique is developed to show that under mild hypotheses the corresponding stochastic system has a transiently robust behaviour. Specifically, after finite time the distribution of the output approximates a Poisson distribution, centred around the deterministic mean. The approximation becomes increasingly accurate, and it holds for increasingly long finite times, as the total protein concentrations grow to infinity. In particular, the stochastic system retains a transient, absolutely robust behaviour corresponding to the deterministic case. This result contrasts with the long-term dynamics of the stochastic system, which eventually must undergo an extinction event that eliminates robustness and is completely different from the deterministic dynamics. The transiently robust behaviour may be sufficient to carry out many forms of robust signal transduction and cellular decision-making in cellular organisms. PMID:27581485

  15. Timing of Early Proterozoic collisional and extensional events in the granulite-gneiss-charnockite-granite complex, Lake Baikal, USSR: A U-Pb, Rb-Sr, and Sm-Nd isotopic study

    SciTech Connect

    Aftalion, M. ); Bibikova, E.V. ); Bowes, D.R. ); Hopwood, A.M. ); Perchuk, L.L. )

    1991-11-01

    In the Sharyzhalgay Complex of the Lake Baikal region in eastern Siberia Early Proterozoic collisional and extensional events were separated by ca. 100 m.yr. The earlier collisional event, associated with the development of granulites and gneisses as the result of high-grade dynamothermal metamorphism, took place close to 1965 {plus minus} 4 Ma. A {sup 207}Pb/{sup 204}Pb vs. {sup 206}Pb/{sup 204}Pb isochron for zircon from five size fractions and a six point Rb-Sr whole-rock errorchron give generally corresponding ages of 1956 {plus minus} 8 and 1963 {plus minus} 163 Ma, respectively. The later extensional event, associated with charnockitization due to the uprise of fluids and heat in a regime corresponding to the middle to upper crustal levels of a Basin and Range-type province, was initiated in the 1880-1860 Ma period. The event was continued with magmatic emplacement of granitic masses into the deep levels of caldera-like structures, possibly during the upper time range of lower concordia intercept ages of 1817 +30/{minus}32 and 1797 +40/{minus}44 Ma for two distinctly different zircon populations in a pyroxene-bearing granodiorite interpreted as an evolved (and contaminated) product of the mantle-derived magma that was the source of CO{sub 2} involved in the charnockitization. Upper intercept ages of 2784 +48/{minus}45 and 2775 +61/{minus}55 Ma indicate late Archean crust at depth as the source region of the incorporated zircon. T{sub DM} ages from Sm-Nd isotopic data show that the protolith of the lithologically layered supracrustal assemblage, subsequently polyphase deformed and polymetamorphosed in Early Proterozoic times, was also formed in Early Proterozoic (not Archean) times.

  16. Radiation-Induced Transient Effects in Near Infrared Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Reed, Robert A.; Pickel, J.; Marshall, P.; Waczynski, A.; McMurray, R.; Gee, G.; Polidan, E.; Johnson, S.; McKeivey, M.; Ennico, K.; Johnson, R.

    2004-01-01

    This viewgraph presentation describes a test simulate the transient effects of cosmic ray impacts on near infrared focal plane arrays. The objectives of the test are to: 1) Characterize proton single events as function of energy and angle of incidence; 2) Measure charge spread (crosstalk) to adjacent pixels; 3) Assess transient recovery time.

  17. A review for identification of initiating events in event tree development process on nuclear power plants

    NASA Astrophysics Data System (ADS)

    Riyadi, Eko H.

    2014-09-01

    Initiating event is defined as any event either internal or external to the nuclear power plants (NPPs) that perturbs the steady state operation of the plant, if operating, thereby initiating an abnormal event such as transient or loss of coolant accident (LOCA) within the NPPs. These initiating events trigger sequences of events that challenge plant control and safety systems whose failure could potentially lead to core damage or large early release. Selection for initiating events consists of two steps i.e. first step, definition of possible events, such as by evaluating a comprehensive engineering, and by constructing a top level logic model. Then the second step, grouping of identified initiating event's by the safety function to be performed or combinations of systems responses. Therefore, the purpose of this paper is to discuss initiating events identification in event tree development process and to reviews other probabilistic safety assessments (PSA). The identification of initiating events also involves the past operating experience, review of other PSA, failure mode and effect analysis (FMEA), feedback from system modeling, and master logic diagram (special type of fault tree). By using the method of study for the condition of the traditional US PSA categorization in detail, could be obtained the important initiating events that are categorized into LOCA, transients and external events.

  18. A review for identification of initiating events in event tree development process on nuclear power plants

    SciTech Connect

    Riyadi, Eko H.

    2014-09-30

    Initiating event is defined as any event either internal or external to the nuclear power plants (NPPs) that perturbs the steady state operation of the plant, if operating, thereby initiating an abnormal event such as transient or loss of coolant accident (LOCA) within the NPPs. These initiating events trigger sequences of events that challenge plant control and safety systems whose failure could potentially lead to core damage or large early release. Selection for initiating events consists of two steps i.e. first step, definition of possible events, such as by evaluating a comprehensive engineering, and by constructing a top level logic model. Then the second step, grouping of identified initiating event's by the safety function to be performed or combinations of systems responses. Therefore, the purpose of this paper is to discuss initiating events identification in event tree development process and to reviews other probabilistic safety assessments (PSA). The identification of initiating events also involves the past operating experience, review of other PSA, failure mode and effect analysis (FMEA), feedback from system modeling, and master logic diagram (special type of fault tree). By using the method of study for the condition of the traditional US PSA categorization in detail, could be obtained the important initiating events that are categorized into LOCA, transients and external events.

  19. Evaluation of WRF-Predicted Near-Hub-Height Winds and Ramp Events over a Pacific Northwest Site with Complex Terrain

    SciTech Connect

    Yang, Qing; Berg, Larry K.; Pekour, Mikhail; Fast, Jerome D.; Newsom, Rob K.; Stoelinga, Mark; Finley, Catherine

    2013-08-01

    The WRF model version 3.3 is used to simulate near hub-height winds and power ramps utilizing three commonly used planetary boundary-layer (PBL) schemes: Mellor-Yamada-Janjic (MYJ), University of Washington (UW), and Yonsei University (YSU). The predicted winds have small mean biases compared with observations. Power ramps and step changes (changes within an hour) consistently show that the UW scheme performed better in predicting up ramps under stable conditions with higher prediction accuracy and capture rates. Both YSU and UW scheme show good performance predicting up- and down- ramps under unstable conditions with YSU being slightly better for ramp durations longer than an hour. MYJ is the most successful simulating down-ramps under stable conditions. The high wind speed and large shear associated with low-level jets are frequently associated with power ramps, and the biases in predicted low-level jet explain some of the shown differences in ramp predictions among different PBL schemes. Low-level jets were observed as low as ~200 m in altitude over the Columbia Basin Wind Energy Study (CBWES) site, located in an area of complex terrain. The shear, low-level peak wind speeds, as well as the height of maximum wind speed are not well predicted. Model simulations with 3 PBL schemes show the largest variability among them under stable conditions.

  20. Unravelling developmental disregard in children with unilateral cerebral palsy by measuring event-related potentials during a simple and complex task

    PubMed Central

    2014-01-01

    Background In a subset of children with unilateral Cerebral Palsy (CP) a discrepancy between capacity and performance of the affected upper limb can be observed. This discrepancy is known as Developmental Disregard (DD). Though the phenomenon of DD has been well documented, its underlying cause is still under debate. DD has originally been explained based on principles of operant conditioning. Alternatively, it has been proposed that DD results from a diminished automaticity of movements, resulting in an increased cognitive load when using the affected hand. To investigate the amount of involved cognitive load we studied Event-Related Potentials (ERPs) preceding task-related motor responses during a single-hand capacity and a dual-hand performance task. It was hypothesised that children with DD show alterations related to long-latency ERP components when selecting a response with the affected upper limb, reflecting increased cognitive load in order to generate an adequate response and especially so within the dual-hand task. Methods Fifteen children with unilateral CP participated in the study. One of the participants was excluded due to major visual impairments. Seven of the remaining participants displayed DD. The other seven children served as a control group. All participants performed two versions of a cue-target paradigm, a single-hand capacity and a dual-hand performance task. The ERP components linked to target presentation were inspected: the mid-latency P2 component and the consecutive long-latency N2b component. Results In the dual-hand performance task children with DD showed an enhancement in mean amplitude of the long-latency N2b component when selecting a response with their affected hand. No differences were found regarding the amplitude of the mid-latency P2 component. No differences were observed regarding the single-hand capacity task. The control group did not display any differences in ERPs linked to target evaluation processes between both

  1. LONG GAMMA-RAY TRANSIENTS FROM COLLAPSARS

    SciTech Connect

    Woosley, S. E.; Heger, Alexander E-mail: alex@physics.umn.edu

    2012-06-10

    In the collapsar model for common gamma-ray bursts (GRBs), the formation of a centrifugally supported disk occurs during the first {approx}10 s following the collapse of the iron core in a massive star. This only occurs in a small fraction of massive stellar deaths, however, and requires unusual conditions. A much more frequent occurrence could be the death of a star that makes a black hole and a weak or absent outgoing shock, but in a progenitor that only has enough angular momentum in its outermost layers to make a disk. We consider several cases where this is likely to occur-blue supergiants with low mass-loss rates, tidally interacting binaries involving either helium stars or giant stars, and the collapse to a black hole of very massive pair-instability supernovae. These events have in common the accretion of a solar mass or so of material through a disk over a period much longer than the duration of a common GRB. A broad range of powers is possible, 10{sup 47}-10{sup 50} erg s{sup -1}, and this brightness could be enhanced by beaming. Such events were probably more frequent in the early universe where mass-loss rates were lower. Indeed, this could be one of the most common forms of gamma-ray transients in the universe and could be used to study first generation stars. Several events could be active in the sky at any one time. Recent examples of this sort of event may have been the Swift transients Sw-1644+57, Sw-2058+0516, and GRB 101225A.

  2. Model Fidelity Study of Dynamic Transient Loads in a Wind Turbine Gearbox: Preprint

    SciTech Connect

    Guo, Y.; Keller, J.; Moan, T.; Xing, Y.

    2013-04-01

    Transient events cause high loads in the drivetrain components so measuring and calculating these loads can improve confidence in drivetrain design. This paper studies the Gearbox Reliability Collaborative 750kW wind turbine gearbox response during transient events using a combined experimental and modeling approach. The transient events include emergency shut-downs and start-ups measured during a field testing period in 2009. The drivetrain model is established in the multibody simulation tool Simpack. A detailed study of modeling fidelity required for accurate load prediction is performed and results are compared against measured loads. A high fidelity model that includes shaft and housing flexibility and accurate bearing stiffnesses is important for the higher-speed stage bearing loads. Each of the transient events has different modeling requirements.

  3. Classification of satellite-based radio frequency transient recordings using sparse approximations over learned dictionaries

    NASA Astrophysics Data System (ADS)

    Moody, Daniela I.; Smith, David A.

    2014-01-01

    Ongoing research at Los Alamos National Laboratory studies the Earth's radio frequency (RF) background utilizing satellite-based RF observations of terrestrial lightning. Such impulsive events occur in the presence of additive noise and structured clutter and appear as broadband nonlinear chirps at a receiver on-orbit due to ionospheric dispersion. The Fast On-orbit Recording of Transient Events (FORTE) satellite provided a rich RF lightning database. Application of modern pattern recognition techniques to this database may further lightning research and potentially improve event discrimination capabilities for future satellite payloads. We extend two established dictionary learning algorithms, K-SVD and Hebbian, for use in classification of satellite RF data. Both algorithms allow us to learn features without relying on analytical constraints or additional knowledge about the expected signal characteristics. We use a pursuit search over the learned dictionaries to generate sparse classification features and discuss performance in terms of event classification using a nearest subspace classifier. We show a use of the two dictionary types in a mixed implementation to showcase algorithm distinctions in extracting discriminative information. We use principal component analysis to analyze and compare the learned dictionary spaces to the real data space, and we discuss some aspects of computational complexity and implementation.

  4. T