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Sample records for events er-5-3 channel

  1. Channel Transmission Loss Studies During Ephemeral Flow Events: ER-5-3 Channel and Cambric Ditch, Nevada Test Site, Nye County, Nevada

    SciTech Connect

    J.J. Miller; S.A. Mizell; R.H. French; D.G. Meadows; M.H. Young

    2005-10-01

    Transmission losses along ephemeral channels are an important, yet poorly understood, aspect of rainfall-runoff prediction. Losses occur as flow infiltrates channel bed, banks, and floodplains. Estimating transmission losses in arid environments is difficult because of the variability of surficial geomorphic characteristics and infiltration capacities of soils and near-surface low-permeability geologic layers (e.g., calcrete). Transmission losses in ephemeral channels are nonlinear functions of discharge and time (Lane, 1972), and vary spatially along the channel reach and with soil antecedent moisture conditions (Sharma and Murthy, 1994). Rainfall-runoff models used to estimate peak discharge and runoff volume for flood hazard assessment are not designed specifically for ephemeral channels, where transmission loss can be significant because of the available storage volume in channel soils. Accuracy of the flow routing and rainfall-runoff models is dependent on the transmission loss estimate. Transmission loss rate is the most uncertain parameter in flow routing through ephemeral channels. This research, sponsored by the U.S. Department of Energy, National Nuclear Security Administration (DOE/NNSA) and conducted at the Nevada Test Site (NTS), is designed to improve understanding of the impact of transmission loss on ephemeral flood modeling and compare various methodologies for predicting runoff from rainfall events. Various applications of this research to DOE projects include more site-specific accuracy in runoff prediction; possible reduction in size of flood mitigation structures at the NTS; and a better understanding of expected infiltration from runoff losses into landfill covers. Two channel transmission loss field experiments were performed on the NTS between 2001 and 2003: the first was conducted in the ER-5-3 channel (Miller et al., 2003), between March and June 2001, and the second was conducted in the Cambric Ditch (Mizell et al., 2005), between April

  2. COMPLETION REPORT FOR WELL CLUSTER ER-5-3

    SciTech Connect

    BECHTEL NEVADA

    2005-12-01

    Well Cluster ER-5-3 was drilled for the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office in support of the Nevada Environmental Restoration Project at the Nevada Test Site, Nye County, Nevada. This cluster of 3 wells was drilled in 2000 and 2001 as part of a hydrogeologic investigation program in Frenchman Flat. The first borehole in the cluster, Well ER-5-3, was drilled in February and March 2000. A 47.0-centimeter surface hole was drilled and cased off to the depth of 374.8 meters. The hole diameter was decreased to 31.1 centimeters for drilling to a total depth of 794.3 meters within welded ash-flow tuff. A piezometer string with 1 slotted interval was installed in the annulus of the surface casing, open to the saturated alluvium. A completion string with 2 slotted intervals was installed in the main hole, open to saturated alluvium and to the welded tuff aquifer. A second piezometer string with 1 slotted interval open to the welded-tuff aquifer was installed outside the completion string. Well ER-5-3 No.2 was drilled about 30 meters west of the first borehole in March 2000, and was recompleted in March 2001. A 66.0-centimeter hole was drilled and cased off to the depth of 613.8 meters. The hole diameter was decreased to 44.5 centimeters and the borehole was drilled and cased off to the depth of 849.0 meters. The hole diameter was decreased once more to 31.1 centimeters for drilling to a total depth of 1,732.2 meters in dolomite. A completion string open to the dolomite (lower carbonate aquifer) was installed. Well ER-5-3 No.3 was drilled approximately 30 meters north of the first 2 boreholes in February 2001. A 66.0-centimeter hole was drilled and cased off to the depth of 36.6 meters, then the main 25.1-centimeter-diameter hole was drilled to a total depth of 548.6 meters in alluvium. A slotted stainless-steel tubing string was installed in the saturated alluvium. A preliminary composite, static water level was measured at

  3. "Channel One" as a Current Events Medium for Secondary Students.

    ERIC Educational Resources Information Center

    Cramer, Rebecca Castle

    1995-01-01

    Students' awareness of current events from a "Channel One" broadcast is examined. Five three-item quizzes tested high school students' short-term recall and knowledge of the news, features, and "Pop Quiz" questions contained in the program. Questionnaires evaluated students' and teachers' attitudes, perception, (students') exposure to other news…

  4. 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.

  5. Morphological impacts of flow events of varying magnitude on ephemeral channels in a semiarid region

    NASA Astrophysics Data System (ADS)

    Hooke, J. M.

    2016-01-01

    Flows in ephemeral channels in semiarid areas are only occasional, and channel changes are episodic; but the flash floods can be devastating and have major geomorphological impacts. Data on morphological impacts of flows in semiarid areas are needed to increase understanding of the dynamics and variability of geomorphic responses in such channels. For this purpose nine reaches of river channel in three catchments in SE Spain - the Nogalte, Torrealvilla, and Salada - have been sites for measurement of flows and their effects over the period 1997-2012. The sites encompass a range of channel size, channel morphology, substrate, vegetation, and position within the catchments. A major difference is between schist and marl bedrock areas. Peak flow stage has been recorded and topography surveyed at frequent intervals and after major flow events. Over the 16-year period, an average of 0.5 flow events per year has been recorded at the schist sites, and an average of one per year at the marl sites; but occurrence has been highly variable from year to year. Threshold daily rainfall for channel flow is mostly 15-20 mm, but higher rainfalls do not always produce flow. One to two major floods have occurred in each of the catchments in the period, including the extreme flood event of September 2012 in the Nogalte catchment. Measured morphological changes have occurred between 2 and 10 times at the monitored sites. The same size flow can have differing effects depending on the state of the system. Low flow can mobilise sediment without producing much morphological change. The long-term trajectory of the reaches and the sediment substrate has a major influence on response to events. Channel change is governed by threshold values of hydraulic conditions. The measurements provide an indication of the scale of maximum erosion and deposition that occurs within the channels and on the floodplains over a range of flow magnitudes and the flow impacts that need to be considered in

  6. Bayesian Statistical Inference in Ion-Channel Models with Exact Missed Event Correction.

    PubMed

    Epstein, Michael; Calderhead, Ben; Girolami, Mark A; Sivilotti, Lucia G

    2016-07-26

    The stochastic behavior of single ion channels is most often described as an aggregated continuous-time Markov process with discrete states. For ligand-gated channels each state can represent a different conformation of the channel protein or a different number of bound ligands. Single-channel recordings show only whether the channel is open or shut: states of equal conductance are aggregated, so transitions between them have to be inferred indirectly. The requirement to filter noise from the raw signal further complicates the modeling process, as it limits the time resolution of the data. The consequence of the reduced bandwidth is that openings or shuttings that are shorter than the resolution cannot be observed; these are known as missed events. Postulated models fitted using filtered data must therefore explicitly account for missed events to avoid bias in the estimation of rate parameters and therefore assess parameter identifiability accurately. In this article, we present the first, to our knowledge, Bayesian modeling of ion-channels with exact missed events correction. Bayesian analysis represents uncertain knowledge of the true value of model parameters by considering these parameters as random variables. This allows us to gain a full appreciation of parameter identifiability and uncertainty when estimating values for model parameters. However, Bayesian inference is particularly challenging in this context as the correction for missed events increases the computational complexity of the model likelihood. Nonetheless, we successfully implemented a two-step Markov chain Monte Carlo method that we called "BICME", which performs Bayesian inference in models of realistic complexity. The method is demonstrated on synthetic and real single-channel data from muscle nicotinic acetylcholine channels. We show that parameter uncertainty can be characterized more accurately than with maximum-likelihood methods. Our code for performing inference in these ion channel

  7. Relative Time-scale for Channeling Events Within Chaotic Terrains, Margaritifer Sinus, Mars

    NASA Technical Reports Server (NTRS)

    Janke, D.

    1985-01-01

    A relative time scale for ordering channel and chaos forming events was constructed for areas within the Margaritifer Sinus region of Mars. Transection and superposition relationships of channels, chaotic terrain, and the surfaces surrounding them were used to create the relative time scale; crater density studies were not used. Channels and chaos in contact with one another were treated as systems. These systems were in turn treated both separately (in order to understand internal relationships) and as members of the suite of Martian erosional forms (in order to produce a combined, master time scale). Channeling events associated with chaotic terrain development occurred over an extended geomorphic period. The channels can be divided into three convenient groups: those that pre-date intercrater plains development post-plains, pre-chasma systems; and those associated with the development of the Vallis Marineris chasmata. No correlations with cyclic climatic changes, major geologic events in other regions on Mars, or triggering phenomena (for example, specific impact events) were found.

  8. Temperature dependence of single-event burnout in n-channel power MOSFETs

    NASA Astrophysics Data System (ADS)

    Johnson, Gregory H.; Schrimpf, Ronald D.; Galloway, Kenneth F.; Koga, Rocky

    1992-12-01

    The temperature dependence of single-event burnout (SEB) in n-channel power MOSFETs is investigated experimentally and analytically. Experimental data are presented which indicate that the SEB susceptibility of the power MOSFET decreases with increasing temperature. A previously reported analytical model that describes the SEB mechanism is updated to include temperature variations. This model is shown to agree with the experimental trends.

  9. 77 FR 39630 - Special Local Regulations for Marine Events; Potomac River, National Harbor Access Channel, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-05

    ... Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking A. Regulatory History... Federal Register (77 FR 82). We received no comments on the proposed rule. No public meeting was requested... Potomac River and National Harbor Access Channel during the event, the effect of this regulation will...

  10. Multi-channel linear descriptors for event-related EEG collected in brain computer interface

    NASA Astrophysics Data System (ADS)

    Pei, Xiao-mei; Zheng, Chong-xun; Xu, Jin; Bin, Guang-yu; Wang, Hong-wu

    2006-03-01

    By three multi-channel linear descriptors, i.e. spatial complexity (Ω), field power (Σ) and frequency of field changes (Φ), event-related EEG data within 8-30 Hz were investigated during imagination of left or right hand movement. Studies on the event-related EEG data indicate that a two-channel version of Ω, Σ and Φ could reflect the antagonistic ERD/ERS patterns over contralateral and ipsilateral areas and also characterize different phases of the changing brain states in the event-related paradigm. Based on the selective two-channel linear descriptors, the left and right hand motor imagery tasks are classified to obtain satisfactory results, which testify the validity of the three linear descriptors Ω, Σ and Φ for characterizing event-related EEG. The preliminary results show that Ω, Σ together with Φ have good separability for left and right hand motor imagery tasks, which could be considered for classification of two classes of EEG patterns in the application of brain computer interfaces.

  11. Joint Isotopic Mass Balance: A Novel Approach to Quantifying Channel Bed to Channel Margins Sediment Transfer during Storm Events

    NASA Astrophysics Data System (ADS)

    Renshaw, C. E.; Magilligan, F. J.

    2014-12-01

    The important role of floodplains in providing temporary storage for a large fraction of the annual sediment load of rivers is well established, but this understanding is largely based on observations of the long-term average behavior of the catchment. Here we combine measurements of the fallout radionuclides Be-7 and Pb-210 and the stable isotopes of water to quantify fine sediment mobilization and storage in a stream and its floodplain during individual intermediate-sized storm events. We demonstrate this method using five intermediate-sized storm events in a small (~15 square km), undeveloped, gravel-bedded tributary of the Connecticut River (USA). We find that in each storm, the mass of sediment deposited onto the margins accounts for almost 90% of the sediment mobilized from the bed, with the remainder of the mobilized bed sediment carried downstream as suspended load. The result that the bed is a net source of sediment to the stream and the margins a net sink is robust, but estimates of the mass of material eroded from the bed and deposited on the margins are less certain. The source of sediment to the bed remains unclear as, consistent with earlier studies, we observe only limited deposition of sediment to the bed during the storm events. The suspended sediment is organic rich and thus its source may be associated with organic decay between storm events. The understanding of the coupled interactions between discharge magnitude and frequency and sediment resupply at the event time scale has important implications for the successful restoration design of discharges that connect channel and floodplain, and for the development of accurate sediment budgets and predictions of sediment flux from a watershed.

  12. Detailed Examination of a Single Conduction Event in a Potassium Channel

    PubMed Central

    2013-01-01

    Although extensively studied, it has proved difficult to describe in detail how potassium ion channels conduct cations and water. We present a computational study that, by using stratified umbrella sampling, examines nearly an entire conduction event of the Kv1.2/2.1 paddle chimera and thereby identifies the expected stable configurations of ions and waters in the selectivity filter of the channel. We describe in detail the motions of the ions and waters during a conduction event, focusing on how waters and ions enter the filter, the rotation of water molecules inside the filter, and how potassium ions are coordinated as they move from a water to a protein environment. Finally, we analyze the small conformational changes undergone by the protein, showing that the stable configurations are most similar to the experimental crystal structure. PMID:24143269

  13. Temperature dependence of single-event burnout in n-channel power MOSFET's

    NASA Astrophysics Data System (ADS)

    Johnson, G. H.; Schrimpf, R. D.; Galloway, K. F.; Koga, R.

    1994-03-01

    The temperature dependence of single-event burnout (SEB) in n-channel power metal-oxide-semiconductor field effect transistors (MOSFET's) is investigated experimentally and analytically. Experimental data are presented which indicate that the SEB susceptibility of the power MOSFET decreases with increasing temperature. A previously reported analytical model that describes the SEB mechanism is updated to include temperature variations. This model is shown to agree with the experimental trends.

  14. Methods for improved forewarning of critical events across multiple data channels

    DOEpatents

    Hively, Lee M [Philadelphia, TN

    2007-04-24

    This disclosed invention concerns improvements in forewarning of critical events via phase-space dissimilarity analysis of data from mechanical devices, electrical devices, biomedical data, and other physical processes. First, a single channel of process-indicative data is selected that can be used in place of multiple data channels without sacrificing consistent forewarning of critical events. Second, the method discards data of inadequate quality via statistical analysis of the raw data, because the analysis of poor quality data always yields inferior results. Third, two separate filtering operations are used in sequence to remove both high-frequency and low-frequency artifacts using a zero-phase quadratic filter. Fourth, the method constructs phase-space dissimilarity measures (PSDM) by combining of multi-channel time-serial data into a multi-channel time-delay phase-space reconstruction. Fifth, the method uses a composite measure of dissimilarity (C.sub.i) to provide a forewarning of failure and an indicator of failure onset.

  15. Increased Anion Channel Activity Is an Unavoidable Event in Ozone-Induced Programmed Cell Death

    PubMed Central

    Errakhi, Rafik; Hiramatsu, Takuya; Meimoun, Patrice; Briand, Joël; Iwaya-Inoue, Mari; Kawano, Tomonori; Bouteau, François

    2010-01-01

    Background Ozone is a major secondary air pollutant often reaching high concentrations in urban areas under strong daylight, high temperature and stagnant high-pressure systems. Ozone in the troposphere is a pollutant that is harmful to the plant. Principal Findings By exposing cells to a strong pulse of ozonized air, an acute cell death was observed in suspension cells of Arabidopsis thaliana used as a model. We demonstrated that O3 treatment induced the activation of a plasma membrane anion channel that is an early prerequisite of O3-induced cell death in A. thaliana. Our data further suggest interplay of anion channel activation with well known plant responses to O3, Ca2+ influx and NADPH-oxidase generated reactive oxygen species (ROS) in mediating the oxidative cell death. This interplay might be fuelled by several mechanisms in addition to the direct ROS generation by O3; namely, H2O2 generation by salicylic and abscisic acids. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during programmed cell death. Significance Collectively, our data indicate that anion efflux is an early key component of morphological and biochemical events leading to O3-induced programmed cell death. Because ion channels and more specifically anion channels assume a crucial position in cells, an understanding about the underlying role(s) for ion channels in the signalling pathway leading to programmed cell death is a subject that warrants future investigation. PMID:20967217

  16. Methods for consistent forewarning of critical events across multiple data channels

    DOEpatents

    Hively, Lee M.

    2006-11-21

    This invention teaches further method improvements to forewarn of critical events via phase-space dissimilarity analysis of data from biomedical equipment, mechanical devices, and other physical processes. One improvement involves conversion of time-serial data into equiprobable symbols. A second improvement is a method to maximize the channel-consistent total-true rate of forewarning from a plurality of data channels over multiple data sets from the same patient or process. This total-true rate requires resolution of the forewarning indications into true positives, true negatives, false positives and false negatives. A third improvement is the use of various objective functions, as derived from the phase-space dissimilarity measures, to give the best forewarning indication. A fourth improvement uses various search strategies over the phase-space analysis parameters to maximize said objective functions. A fifth improvement shows the usefulness of the method for various biomedical and machine applications.

  17. 33 CFR 100.35T05-0482 - Special Local Regulations for Marine Events, Wrightsville Channel; Wrightsville Beach, NC.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Marine Events, Wrightsville Channel; Wrightsville Beach, NC. 100.35T05-0482 Section 100.35T05-0482..., Wrightsville Channel; Wrightsville Beach, NC. (a) Regulated area. The following location is a regulated area... Bascule Bridge, mile 283.1, latitude 34°13′06″ North, longitude 077°48′44″ West, at Wrightsville...

  18. 33 CFR 100.35T05-0482 - Special Local Regulations for Marine Events, Wrightsville Channel; Wrightsville Beach, NC.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Marine Events, Wrightsville Channel; Wrightsville Beach, NC. 100.35T05-0482 Section 100.35T05-0482..., Wrightsville Channel; Wrightsville Beach, NC. (a) Regulated area. The following location is a regulated area... Bascule Bridge, mile 283.1, latitude 34°13′06″ North, longitude 077°48′44″ West, at Wrightsville...

  19. Simulating single-event burnout of n-channel power MOSFET's

    SciTech Connect

    Johnson, G.H.; Hohl, J.H.; Schrimpf, R.D.; Galloway, K.F. )

    1993-05-01

    Heavy ions are ubiquitous in a space environment. Single-event burnout of power MOSFET's is a sudden catastrophic failure mechanism that is initiated by the passage of a heavy ion through the device structure. The passage of the heavy ion generates a current filament that locally turns on a parasitic n-p-n transistor inherent to the power MOSFET. Subsequent high currents and high voltage in the device induce second breakdown of the parasitic bipolar transistor and hence meltdown of the device. This paper presents a model that can be used for simulating the burnout mechanism in order to gain insight into the significant device parameters that most influence the single-event burnout susceptibility of n-channel power MOSFET's.

  20. Examination of event magnitude, contributing drainage basin area, channel gradient, and rainfall influences on channel yield rates of post-fire debris flows

    NASA Astrophysics Data System (ADS)

    Gartner, J. E.; Cannon, S. H.; Santi, P.

    2011-12-01

    Development of methods for estimating volumes of post-fire debris-flow material along drainage networks requires a better understanding of the factors that control channel erosion and deposition within recently-burned drainage basins. The amount of material eroded and deposited by debris flows at locations along a channel can be quantified using the channel yield rate; the change in debris-flow volume per unit length of channel caused by passage of a debris flow. Here, we use channel yield rates measured in basins recently burned the 2009 Station fire in the San Gabriel Mountains of southern California to examine relationships between these rates and event magnitude, contributing drainage basin area, channel gradient, and rainfall characteristics. Following the Station fire and prior to any significant rainstorms, two to nine cross section surveys were established along the entire lengths of the main channels of three steep, rugged drainage basins. Surveys of the channel cross sections were made both before and after two distinct debris-flow triggering storms. These data were used to calculate post-fire debris-flow channel yield rates at 40 locations. Tipping-bucket rain gages installed near the surveyed channels provide rainfall amounts and intensities. Measurements of the amount of material removed from debris-retention basins located at the drainage basin outlets provide information on debris-flow volumes deposited at drainage basin outlets. High-resolution LiDAR data (1 meter) provide accurate elevation data for defining contributing drainage basin areas and channel gradients. The measured channel yield rates varied from 1 to 19 m3/m, with a mean of 4 m3/m and standard deviation of 5 m3/m. The greatest yield rates coincide with locations immediately downstream of field-mapped bedrock steps or channel junctions. The coincidence with bedrock steps suggests that in-channel "fire-hose" entrainment is a major contributor to debris-flow volume. High channel yield

  1. Photogrammetric recognition of subglacial drainage channels during glacier lake outburst events

    NASA Astrophysics Data System (ADS)

    Schwalbe, Ellen; Koschitzki, Robert

    2016-04-01

    In recent years, many glaciers all over the world have been distinctly retreating and thinning. One of the consequences of this is the increase of so called glacier lake outburst flood events (GLOFs): Lakes that have been dammed by a glacier spontaneously start to drain through a subglacial channel underneath the glacier due to their outweighing hydrostatic pressure. In a short period of time, the lake water drains under the glacier and causes floods in downstream valleys. In many cases the latter become hazardous for people and their property. Due to glacier movement, the tunnel will soon collapse, and the glacier lake refills, thus starting a new GLOF cycle. The mechanisms ruling GLOF events are yet still not fully understood by glaciologists. Thus, there is a demand for data and measurement values that can help to understand and model the phenomena. In view of the above, we will show how photogrammetric image sequence analysis can be used to collect data which allows for drawing conclusions about the location and development of a subglacial channel. The work is a follow-up on earlier work on a photogrammetric GLOF early warning system (Mulsow et. al., 2013). For the purpose of detecting the subglacial tunnel, a camera has been installed in a pilot study to observe the area of the Colonia glacier (Northern Patagonian ice field) where it dams the lake Lago Cachet II. To verify the hypothesis, that the course of the subglacial tunnel is indicated by irregular surface motion patterns during its collapse, the camera acquired image sequences of the glacier surface during several GLOF events. Applying LSM-based tracking techniques to these image sequences, surface feature motion trajectories could be obtained for a dense raster of glacier points. Since only a single camera has been used for image sequence acquisition, depth information is required to scale the trajectories. Thus, for scaling and georeferencing of the measurements a GPS-supported photogrammetric network

  2. Estimation of Channel-Forming Discharge and Large-Event Geomorphic Response Using HEC-RAS

    NASA Astrophysics Data System (ADS)

    Hamilton, P.; Strom, K.; Hosseiny, S. M. H.

    2015-12-01

    The goal of the present work was to consider the functionality and applicability of HEC-RAS sediment transport simulations in two situations. The first was as a mode for obtaining quick estimates of the effective discharge, one measure of channel-forming discharge, and the second was as a mode to quickly estimate sediment transport and the commensurate potential erosion and deposition during large flood events. Though there are many other sediment transport and morphodynamic models available, e.g., CCHE1D, Nays2DH, we were interested in using HEC-RAS since this is the model of choice for many regulatory bodies, e.g., FEMA, cities, and counties. This makes using the sediment transport capability of HEC-RAS a natural extension of models that already otherwise exist and are well calibrated. In first looking at the utility of these models, we wanted to estimate the effective discharge of streams. Effective discharge is one way of defining the channel-forming discharge for a stream and is therefore an important parameter in natural channel design and restoration efforts. By running this range of floods, one can easily obtain an estimate for recurrence interval most responsible for moving the majority of sediment over a long time period. Results were compared to data collected within our research group on the Brazos River (TX). Effective discharge is an important estimate, particularly in understanding the equilibrium channel condition. Nevertheless, large floods are contemporaneously catastrophic and understanding their potential effects is desirable. Finally, we performed some sensitivity analysis to better understand the underlying assumptions of the various sediment transport model options and how they might affect the outcome of the aforementioned computations.

  3. An analysis of large Forbush decrease events using phase diagrams of view channels of the Nagoya multidirectional muon telescope

    NASA Astrophysics Data System (ADS)

    Kalugin, G.; Kabin, K.

    2015-02-01

    Large Forbush decrease (FD) events are analysed using data recorded by the ground-based Nagoya multi-directional muon telescope in Japan. As a part of the analysis we introduce a phase diagram for the channels of telescope, which provides more robust information about characteristics of events. Specifically, the slope of the regression line in the phase diagram represents the FD amplitude which can be computed for different channels. This allows us to analyze the dependence of the FD amplitude on the rigidity of CR particles. Two models for this dependence are considered, a power law and exponential and the former is found to be more suitable for the considered events. In terms of the power-law index and the FD amplitude the events are split into two groups. It is shown that the larger events are characterized by smaller power-law index than the smaller ones.

  4. 77 FR 23119 - Annual Marine Events in the Eighth Coast Guard District, Smoking the Sound; Biloxi Ship Channel...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... SECURITY Coast Guard 33 CFR Part 100 Annual Marine Events in the Eighth Coast Guard District, Smoking the Sound; Biloxi Ship Channel; Biloxi, MS AGENCY: Coast Guard, DHS. ACTION: Notice of enforcement of regulation. SUMMARY: The Coast Guard will enforce Special Local Regulations for the Smoking the Sound...

  5. Prestimulus EEG microstates influence visual event-related potential microstates in field maps with 47 channels.

    PubMed

    Kondakor, I; Lehmann, D; Michel, C M; Brandeis, D; Kochi, K; Koenig

    1997-01-01

    The influence of the immediate prestimulus EEG microstate (sub-second epoch of stable topography/map landscape) on the map landscape of visually evoked 47-channel event-related potential (ERP) microstates was examined using the frequent, non-target stimuli of a cognitive paradigm (12 volunteers). For the two frequent prestimulus microstate classes (oriented left anterior-right posterior and right anterior-left posterior), ERP map series were selectively averaged. The post-stimulus ERP grand average map series was segmented into microstates; 10 were found. The centroid locations of positive and negative map areas extracted as landscape descriptors. Significant differences (MANOVAs and t-tests) between the two prestimulus classes were found in four of the ten ERP microstates. The relative orientation of the two ERP microstate classes was the same as prestimulus in some ERP microstates, but reversed in others. Thus, brain electric microstates at stimulus arrival influence the landscapes of the post-stimulus ERP maps and therefore, information processing; prestimulus microstate effects differed for different post-stimulus ERP microstates.

  6. Universality of Poisson indicator and Fano factor of transport event statistics in ion channels and enzyme kinetics.

    PubMed

    Chaudhury, Srabanti; Cao, Jianshu; Sinitsyn, Nikolai A

    2013-01-17

    We consider a generic stochastic model of ion transport through a single channel with arbitrary internal structure and kinetic rates of transitions between internal states. This model is also applicable to describe kinetics of a class of enzymes in which turnover events correspond to conversion of substrate into product by a single enzyme molecule. We show that measurement of statistics of single molecule transition time through the channel contains only restricted information about internal structure of the channel. In particular, the most accessible flux fluctuation characteristics, such as the Poisson indicator (P) and the Fano factor (F) as function of solute concentration, depend only on three parameters in addition to the parameters of the Michaelis-Menten curve that characterizes average current through the channel. Nevertheless, measurement of Poisson indicator or Fano factor for such renewal processes can discriminate reactions with multiple intermediate steps as well as provide valuable information about the internal kinetic rates.

  7. Ambient Tremor Triggered by Long-term Slow Slip Event in Bungo Channel, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Obara, K.; Hirose, H.; Matsuzawa, T.; Tanaka, S.; Maeda, T.

    2014-12-01

    Episodic tremor and slip (ETS) is a stick-slip in the transition zone between locked and stable sliding zones on the plate interface in Southwest Japan and Cascadia. ETS episode with duration of several days usually recurs at interval of several months at each segment. On the other hand, in the Bungo channel region where is the western edge of the ETS zone in SW Japan, tremor activity continued for several months during the long-term slow slip event (SSE) in 2003 and 2010. In this paper, the relationship between long-term SSE and surrounded triggered tremor is discussed. Tremor triggered by the long-term SSE is spatially localized in the narrow width of about 10 km at the shallowest part of the tremor zone, and at the neighboring area just downdip from the source fault of the SSE. The frequency distribution of tremor along the dip direction during the SSE period is consistent with the spatial distribution of total slip estimated for 2010 SSE. Therefore, the slip of the long-term SSE penetrated in the ETS zone may generate tremor. The daily number of the activated tremor is 12-14 during the SSE; however, it is 40-50 for regular ETS episode during the inter-SSE period. On the other hand, slip rates of the long-term SSE and ETS are typically 1 mm/d and 3 mm/d, respectively. Therefore, tremor rate may be controlled by slip rate. After SSEs in 2003 and 2010, tremor activity seems to slightly increase in the east region within 50 km from the triggered tremor area. Such 7-year period variation in tremor activity is observed in only the shallower side of the tremor zone. Moreover, pattern of the long-term variation seems to slightly migrate to east during a few years. We interpret that a tiny transient slip after the long-term SSE slowly propagates between transition and locked zones. Tremor activity at the shallowest part of the tremor zone in the Bungo channel continued longer than that of regular ETS in the late 2006 during the inter-SSE period. Associated tiny GPS

  8. Evaluating the use of drone photogrammetry for measurement of stream channel morphology and response to high flow events

    NASA Astrophysics Data System (ADS)

    Price, Katie; Ballow, William

    2015-04-01

    great promise for the drone photogrammetry methods, which encouraged the exploration of the possibility of repeat aerial surveys to evaluate channel response to high flow events. Repeat drone surveys were performed following a sequence of high-flow events in Proctor Creek to evaluate the possibility of using these methods for assessment of stream channel response to flooding.

  9. Channel Geometry and Flood Flows: Quantifying over-bank flow dynamics during high-flow events in North Carolina's floodplains

    NASA Astrophysics Data System (ADS)

    Lovette, J. P.; Duncan, J. M.; Vimal, S.; Band, L. E.

    2015-12-01

    Natural riparian areas play numerous roles in the maintenance and improvement of stream water quality. Both restoration of riparian areas and improvement of hydrologic connectivity to the stream are often key goals of river restoration projects. These management actions are designed to improve nutrient removal by slowing and treating overland flow delivered from uplands and by storing, treating, and slowly releasing streamwater from overbank inundation during flood events. A major question is how effective this storage of overbank flow is at treating streamwater based on the cumulative time stream discharge at a downstream location has spent in shallower, slower overbank flow. The North Carolina Floodplain Mapping Program maintains a detailed statewide Flood Risk Information System (FRIS) using HEC-RAS modeling, lidar, and detailed surveyed river cross-sections. FRIS provides extensive information regarding channel geometry on approximately 39,000 stream reaches (a slightly coarser spatial resolution than the NHD+v2 dataset) with tens of cross-sections for each reach. We use this FRIS data to calculate volume and discharge from floodplain riparian areas separately from in-channel flow during overbank events. Preliminary results suggest that a small percentage of total annual discharge interacts with the full floodplain extent along a stream reach due to the infrequency of overbank flow events. However, with the significantly different physical characteristics of the riparian area when compared to the channel itself, this overbank flow can provide unique services to water quality. Our project aims to use this information in conjunction with data from the USGS SPARROW program to target non-point source hotspots of Nitrogen and Phosphorus addition and removal. By better understanding the flow dynamics within riparian areas during high flow events, riparian restoration projects can be carried out with improved efficacy.

  10. 78 FR 34881 - Special Local Regulations; Marine Events, Wrightsville Channel; Wrightsville Beach, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-11

    ... Rulemaking for this event in the Federal Register (78 FR 19155). We received no comments on the proposed rule... INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations; Marine Events,...

  11. 75 FR 56024 - Special Local Regulations for Marine Events, Wrightsville Channel; Wrightsville Beach, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-15

    ..., 2008, issue of the Federal Register (73 FR 3316). Public Meeting We do not now plan to hold a public... 2 Battleship Full and Half Iron Distance Triathlon'', to be held on the waters of Banks Channel... will sponsor the ``Beach 2 Battleship Full and Half Iron Distance Triathlon'' on the waters of...

  12. 78 FR 19155 - Special Local Regulations; Marine Events, Wrightsville Channel; Wrightsville Beach, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ...: Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed..., 2008, issue of the Federal Register (73 FR 3316). 4. Public Meeting We do not now plan to hold a public... Channel; Wrightsville Beach, NC'' in the Federal Register (77 FR 35321). We received no comments on...

  13. Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03693 Channel

    This channel is located south of Iani Chaos.

    Image information: VIS instrument. Latitude -10.9N, Longitude 345.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. 78 FR 20849 - Special Local Regulations; Marine Events, Potomac River; National Harbor Access Channel, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    ... DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking A. Public... Act notice regarding our public dockets in the January 17, 2008, issue of the Federal Register (73 FR... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations; Marine Events, Potomac...

  15. 77 FR 35321 - Special Local Regulations for Marine Events, Wrightsville Channel; Wrightsville Beach, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... FR Federal Register NPRM Notice of Proposed Rulemaking A. Public Participation and Request for... regarding our public dockets in the January 17, 2008, issue of the Federal Register (73 FR 3316). 4. Public... proposes a Special Local Regulation for the ``Swim Harbor Island'' swim event, to be held on the...

  16. Influences of high-flow events on a stream channel altered by construction of a highway bridge: a case study

    USGS Publications Warehouse

    Hedrick, Lara B.; Welsh, Stuart A.; Anderson, James T.

    2009-01-01

    Impacts of highway construction on streams in the central Appalachians are a growing concern as new roads are created to promote tourism and economic development in the area. Alterations to the streambed of a first-order stream, Sauerkraut Run, Hardy County, WV, during construction of a highway overpass included placement and removal of a temporary culvert, straightening and regrading of a section of stream channel, and armourment of a bank with a reinforced gravel berm. We surveyed longitudinal profiles and cross sections in a reference reach and the altered reach of Sauerkraut Run from 2003 through 2007 to measure physical changes in the streambed. During the four-year period, three high-flow events changed the streambed downstream of construction including channel widening and aggradation and then degradation of the streambed. Upstream of construction, at a reinforced gravel berm, bank erosion was documented. The reference section remained relatively unchanged. Knowledge gained by documenting channel changes in response to natural and anthropogenic variables can be useful for managers and engineers involved in highway construction projects.

  17. Reach-scale channel sensitivity to multiple human activities and natural events: Lower Santa Clara River, California, USA

    NASA Astrophysics Data System (ADS)

    Downs, Peter W.; Dusterhoff, Scott R.; Sears, William A.

    2013-05-01

    Understanding the cumulative impact of natural and human influences on the sensitivity of channel morphodynamics, a relative measure between the drivers for change and the magnitude of channel response, requires an approach that accommodates spatial and temporal variability in the suite of primary stressors. Multiple historical data sources were assembled to provide a reach-scale analysis of the lower Santa Clara River (LSCR) in Ventura County, California, USA. Sediment supply is naturally high due to tectonic activity, earthquake-generated landslides, wildfires, and high magnitude flow events during El Niño years. Somewhat typically for the region, the catchment has been subject to four reasonably distinct land use and resource management combinations since European-American settlement. When combined with analysis of channel morphological response (quantifiable since ca. 1930), reach-scale and temporal differences in channel sensitivity become apparent. Downstream reaches have incised on average 2.4 m and become narrower by almost 50% with changes focused in a period of highly sensitive response after about 1950 followed by forced insensitivity caused by structural flood embankments and a significant grade control structure. In contrast, the middle reaches have been responsive but are morphologically resilient, and the upstream reaches show a mildly sensitive aggradational trend. Superimposing the natural and human drivers for change reveals that large scale stressors (related to ranching and irrigation) have been replaced over time by a suite of stressors operating at multiple spatial scales. Lower reaches have been sensitive primarily to 'local' scale impacts (urban growth, flood control, and aggregate mining) whereas, upstream, catchment-scale influences still prevail (including flow regulation and climate-driven sediment supply factors). These factors illustrate the complexity inherent to cumulative impact assessment in fluvial systems, provide evidence for a

  18. 33 CFR 100.35T05-0276 - Special Local Regulations for Marine Events; Potomac River, National Harbor Access Channel, MD.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Marine Events; Potomac River, National Harbor Access Channel, MD. 100.35T05-0276 Section 100.35T05-0276 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY REGATTAS AND MARINE PARADES SAFETY OF LIFE ON NAVIGABLE WATERS § 100.35T05-0276 Special Local Regulations for Marine Events;...

  19. 33 CFR 100.35T05-0276 - Special Local Regulations for Marine Events; Potomac River, National Harbor Access Channel, MD.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Marine Events; Potomac River, National Harbor Access Channel, MD. 100.35T05-0276 Section 100.35T05-0276 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY REGATTAS AND MARINE PARADES SAFETY OF LIFE ON NAVIGABLE WATERS § 100.35T05-0276 Special Local Regulations for Marine Events;...

  20. Investigating reaction pathways in rare events simulations of antibiotics diffusion through protein channels.

    PubMed

    Hajjar, Eric; Kumar, Amit; Ruggerone, Paolo; Ceccarelli, Matteo

    2010-11-01

    In Gram-negative bacteria, outer-membrane protein channels, such as OmpF of Escherichia coli, constitute the entry point of various classes of antibiotics. While antibacterial research and development is declining, bacterial resistance to antibiotics is rising and there is an emergency call for a new way to develop potent antibacterial agents and to bring them to the market faster and at reduced cost. An emerging strategy is to follow a bottom-up approach based on microscopically founded computational based screening, however such strategy needs better-tuned methods. Here we propose to use molecular dynamics (MD) simulations combined with the metadynamics algorithm, to study antibiotic translocation through OmpF at a molecular scale. This recently designed algorithm overcomes the time scale problem of classical MD by accelerating some reaction coordinates. It is expected that the initial assumption of the reaction coordinates is a key determinant for the efficiency and accuracy of the simulations. Previous studies using different computational schemes for a similar process only used one reaction coordinate, which is the directionality. Here we go further and see how it is possible to include more informative reaction coordinates, accounting explicitly for: (i) the antibiotic flexibility and (ii) interactions with the channel. As model systems, we select two compounds covering the main classes of antibiotics, ampicillin and moxifloxacine. We decipher the molecular mechanism of translocation of each antibiotic and highlight the important parameters that should be taken into account for improving further simulations. This will benefit the screening and design for antibiotics with better permeation properties.

  1. An interactive 24-channel event-logging system based on the AIM 65 single-board microcomputer.

    PubMed

    Thomas, S R; Grimwood, M; Iversen, S D

    1984-06-01

    Measures of the spontaneous behaviour of animals commonly involve the repetitive counting of behavioural events over successive periods of time following some experimental treatment. An automated event-logging system has been designed for such applications. The system is based on an AIM 65 microcomputer with 4 Kbytes of random-access memory and facilities for manual event-logging through the keyboard, or automatic logging via a signal-conditioning buffer, connected to the backplane connector of the computer. The control program is written in 6500 machine code and stored in an onboard, read-only, memory chip. The software generates a simple interactive dialogue for the selection of operating options which include manual or automatic modes, configuration of active channels, duration and number of logging cycles, and the choice of printed or transmitted output. The microcomputer can also be instructed to pause and then to restart, to print out its current status, or to abort. The system has been used over a period of 18 months in numerous experiments in this laboratory, and has proved to be reliable, accurate and entirely suited to its application.

  2. A Bed Load Monitoring System for Real Time Sediment Transport and Bed Morphology during Channel Altering Events

    NASA Astrophysics Data System (ADS)

    Curran, J. C.; Waters, K. A.; Cannatelli, K.

    2014-12-01

    A new technique is presented that provides continuous measurement of sediment movement over the length of a flume. Real-time measurements of bed changes over a reach are a missing piece needed to link bed morphology with sediment transport processes during unsteady flows when the bed adjusts quickly to changing transport rates or visual observation of the bed is precluded by fine sediment in the water column. A bed load monitoring system (BLMS) was developed that records the sediment and water loads over discrete bed lengths throughout a flow event. It was designed for laboratory application where controlled measurement methods are possible. Upon data processing, the BLMS provides a continuous measure of the sediment load across the bed from which sediment movement rates through the reach, including areas of temporary aggradation or degradation, can be reconstructed. Examples are provided of how the bed load monitoring system has been applied during sediment feed and sediment recirculation experiments to further the interpretation of channel processes occurring during large flows. We detail the use of the BLMS to measure bed slopes during unsteady flows and to measure the movement of sediment downstream following different methods of dam removal. We evaluate the BLMS for use where DEM differencing was also applied to illustrate the information provided by each measurement method. Exciting implications of future research that incorporates a BLMS include a more informed management of river systems as a result of improved temporal predictions of sediment movement and the associated changes in channel slope and morphology.

  3. Modeling the Effectiveness of a Storm Surge Barrier System for the Houston Ship Channel during Hurricane Events

    NASA Astrophysics Data System (ADS)

    Torres, J.; Fang, N.; Bedient, P. B.; Christian, J.

    2013-12-01

    The Houston Ship Channel (HSC) is home to the second-busiest port in the nation in terms of overall tonnage, and contains one of the largest petrochemical complexes in the world. As such, undisturbed operations of the HSC are vital to ensuring the economic prosperity of local, state, and national interests. History has proven that coastal infrastructure systems and operations at the HSC are easily disrupted by rainfall and storm surge from intense hurricanes (e.g. Hurricane Ike). To quantitatively evaluate flood and storm surge vulnerability, a coupled riverine-coastal hydraulic model is developed for the HSC and Galveston Bay as an initial testbed for simulating extreme flooding scenarios. A numerical investigation is made on the coupled interactions of upstream watershed runoff and downstream surge level occurrences, as well as the effectiveness of a proposed storm surge gate protecting inland HSC infrastructure during a simulated Hurricane Ike event, and associated Ike variations. Sensitivities in peak stage, instantaneous flow, and relative timing of these events are explored for Hurricane Ike rainfall-surge conditions and various perturbations related thereto. Results show that a surge gate system can be effective to reduce flood elevation and floodplain extent in the HSC area, but that net flood protection is largely dependent on the varied timings on the watershed rainfall-runoff and coastal surge dynamics.

  4. Influential factors on debris flow events and hillslope-channel connectivity in Alpine regions: case studies from two Alpine regions in Styria, Austria

    NASA Astrophysics Data System (ADS)

    Traper, Sandra; Pöppl, Ronald; Rascher, Eric; Sass, Oliver

    2016-04-01

    In recent times different types of natural disasters like debris flow events have attracted increasing attention worldwide, since they can cause great damage and loss of infrastructure or even lives is not unusual when it comes to such an event. The engagement with debris flows is especially important in mountainous areas like Austria, since Alpine regions have proved to be particularly prone to the often harmful consequences of such events because of increasing settlement of previously uninhabited regions. Due to those frequently damaging effects of debris flows, research on this kind of natural disaster often focuses on mitigation and recovery measures after an event and on how to restore the initial situation. However, a view on the situation of an area, where severe debris flows recently occurred and are well documented, before the actual event can aid in discovering important preparatory factors that contribute to initiating debris flows and hillslope-channel connectivity in the first place. Valuable insights into the functioning and preconditions of debris flows and their potential connectivity to the main channel can be gained. The study focuses on two geologically different areas in the Austrian Alps, which are both prone to debris flows and have experienced rather severe events recently. Based on data from debris flow events in two regions in Styria (Austria), the Kleinsölk and the Johnsbach valleys, the aim of the study is to identify factors which influence the development of debris flows and the potential of such debris flows to reach the main channel potentially clogging up the river (hillslope-channel connectivity). The degree of hillslope-channel coupling was verified in extensive TLS and ALS surveys, resulting in DEMs of different resolution and spatial extension. Those factors are obtained, analyzed and evaluated with DEM-based GIS- and statistical analyses. These include factors that are attributed to catchment topography, such as slope angle

  5. Bioavailability of Mercury to Riverine Food Webs as a Function of Flood-Event Inundation of Channel Boundary Sediments

    NASA Astrophysics Data System (ADS)

    Singer, M. B.; Pellachini, C.; Blum, J. D.; Marvin-DiPasquale, M. C.; Donovan, P. M.

    2013-12-01

    Bioavailability of sediment-adsorbed contaminants to food webs in river corridors is typically controlled by biological, chemical, and physical factors, but understanding of their respective influences is limited due to a dearth of landscape-scale investigations of these biogeochemical links. Studies that account for the dynamics and interactions of hydrology and sediment transport in affecting the reactivity of sediment-adsorbed heavy metals such as mercury (Hg) are particularly lacking. Sequences of flood events generate complex inundation histories with banks, terraces, and floodplains that have the potential to alter local redox conditions and thereby affect the oxidation of elemental Hg0 to inorganic Hg(II), and the microbial conversion of Hg(II) to methylmercury (MeHg), potentially increasing the risk of Hg uptake into aquatic food webs. However, the probability distributions of saturation/inundation frequency and duration are typically unknown for channel boundaries along sediment transport pathways, and landscape-scale characterizations of Hg reactivity are rare along contaminated rivers. This research provides the first links between the dynamics of physical processes and biochemical processing and uptake into food webs in fluvial systems beset by large-scale mining contamination. Here we present new research on Hg-contaminated legacy terraces and banks along the Yuba River anthropogenic fan, produced by 19th C. hydraulic gold mining in Northern California. To assess the changes in Hg(II) availability for methylation and MeHg bioavailability into the food web, we combine numerical modeling of streamflow with geochemical assays of total Hg and Hg reactivity to identify hot spots of toxicity within the river corridor as a function of cycles of wetting/drying. We employ a 3D hydraulic model to route historical streamflow hydrographs from major flood events through the Yuba and Feather Rivers into the Central Valley to assess the frequency and duration of

  6. Single doses of piracetam affect 42-channel event-related potential microstate maps in a cognitive paradigm.

    PubMed

    Michel, C M; Lehmann, D

    1993-01-01

    We examined whether a single administration of piracetam produces dose-dependent effects on brain functions in healthy young men. In 6 subjects, 42-channel event-related EEG potential maps (ERP) were recorded during a task requiring subjects to watch single digits presented in a pseudorandom order on a screen and to press a button after all triplets of three consecutive odd or even digits. The ERP maps to the three digits of the correctly detected triplets were analyzed in terms of their mapped ERP field configuration (landscape). Different landscapes of the maps indicate different configuration of the activated neural population and therefore reflect different functional microstates of the brain. In order to identify these microstates, adaptive segmentation of the map series based on their landscapes was done. Nineteen time segments were found. These segments were tested for direct effects on brain function of three single doses of piracetam (2.9, 4.8 or 9.6 g) and a placebo given double-blind in balanced order. Piracetam mainly affected the map landscape of the time segments following the triplet's last digit. U-shaped dose-dependent effects were found; they were strongest after 4.8 g piracetam. Since these particular ERP segments are recognized to be strongly correlated to cognitive functions, the present findings suggest that single medium doses of piracetam selectively activate differently located or oriented neurons during cognitive steps of information processing.

  7. A single crossing-over event in voltage-sensitive Na+ channel genes may cause critical failure of dengue mosquito control by insecticides.

    PubMed

    Hirata, Koichi; Komagata, Osamu; Itokawa, Kentaro; Yamamoto, Atsushi; Tomita, Takashi; Kasai, Shinji

    2014-08-01

    The voltage-sensitive sodium (Na+) channel (Vssc) is the target site of pyrethroid insecticides. Pest insects develop resistance to this class of insecticide by acquisition of one or multiple amino acid substitution(s) in this channel. In Southeast Asia, two major Vssc types confer pyrethroid resistance in the dengue mosquito vector Aedes aegypti, namely, S989P+V1016G and F1534C. We expressed several types of Vssc in Xenopus oocytes and examined the effect of amino acid substitutions in Vssc on pyrethroid susceptibilities. S989P+V1016G and F1534C haplotypes reduced the channel sensitivity to permethrin by 100- and 25-fold, respectively, while S989P+V1016G+F1534C triple mutations reduced the channel sensitivity to permethrin by 1100-fold. S989P+V1016G and F1534C haplotypes reduced the channel sensitivity to deltamethrin by 10- and 1-fold (no reduction), respectively, but S989P+V1016G+F1534C triple mutations reduced the channel sensitivity to deltamethrin by 90-fold. These results imply that pyrethroid insecticides are highly likely to lose their effectiveness against A. aegypti if such a Vssc haplotype emerges as the result of a single crossing-over event; thus, this may cause failure to control this key mosquito vector. Here, we strongly emphasize the importance of monitoring the occurrence of triple mutations in Vssc in the field population of A. aegypti.

  8. Evidence for s-channel single-top-quark production in events with one charged lepton and two jets at CDF.

    PubMed

    Aaltonen, T; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Butti, P; Buzatu, A; Calamba, A; Camarda, S; Campanelli, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Cho, K; Chokheli, D; Clark, A; Clarke, C; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Cremonesi, M; Cruz, D; Cuevas, J; Culbertson, R; d'Ascenzo, N; Datta, M; de Barbaro, P; Demortier, L; Deninno, M; D'Errico, M; Devoto, F; Di Canto, A; Di Ruzza, B; Dittmann, J R; Donati, S; D'Onofrio, M; Dorigo, M; Driutti, A; Ebina, K; Edgar, R; Elagin, A; Erbacher, R; Errede, S; Esham, B; Farrington, S; Fernández Ramos, J P; Field, R; Flanagan, G; Forrest, R; Franklin, M; Freeman, J C; Frisch, H; Funakoshi, Y; Galloni, C; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González López, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gramellini, E; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Han, J Y; Happacher, F; Hara, K; Hare, M; Harr, R F; Harrington-Taber, T; Hatakeyama, K; Hays, C; Heinrich, J; Herndon, M; Hocker, A; Hong, Z; Hopkins, W; Hou, S; Hughes, R E; Husemann, U; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kambeitz, M; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S H; Kim, S B; Kim, Y J; Kim, Y K; Kimura, N; Kirby, M; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Kruse, M; Kuhr, T; Kurata, M; Laasanen, A T; Lammel, S; Lancaster, M; Lannon, K; Latino, G; Lee, H S; Lee, J S; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lipeles, E; Lister, A; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucchesi, D; Lucà, A; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Marchese, L; Margaroli, F; Marino, P; Martínez, M; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M J; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Nigmanov, T; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagliarone, C; Palencia, E; Palni, P; Papadimitriou, V; Parker, W; Pauletta, G; Paulini, M; Paus, C; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Pranko, A; Prokoshin, F; Ptohos, F; Punzi, G; Ranjan, N; Redondo Fernández, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodriguez, T; Rolli, S; Ronzani, M; Roser, R; Rosner, J L; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, E E; Schwarz, T; Scodellaro, L; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sliwa, K; Smith, J R; Snider, F D; Song, H; Sorin, V; St Denis, R; Stancari, M; Stentz, D; Strologas, J; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thomson, E; Thukral, V; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Ukegawa, F; Uozumi, S; Velev, G; Vellidis, C; Vernieri, C; Vidal, M; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Vázquez, F; Wagner, P; Wallny, R; Wang, S M; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wilbur, S; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Zanetti, A M; Zeng, Y; Zhou, C; Zucchelli, S

    2014-06-13

    We report evidence for s-channel single-top-quark production in proton-antiproton collisions at center-of-mass energy sqrt[s] = 1.96 TeV using a data set that corresponds to an integrated luminosity of 9.4 fb(-1) collected by the Collider Detector at Fermilab. We select events consistent with the s-channel process including two jets and one leptonically decaying W boson. The observed significance is 3.8 standard deviations with respect to the background-only prediction. Assuming a top-quark mass of 172.5 GeV/c(2), we measure the s-channel cross section to be 1.41(-0.42)(+0.44) pb.

  9. Evidence for s-Channel Single-Top-Quark Production in Events with One Charged Lepton and Two Jets at CDF

    NASA Astrophysics Data System (ADS)

    Aaltonen, T.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D'Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Elagin, A.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucà, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Martínez, M.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Ranjan, N.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Vázquez, F.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Zanetti, A. M.; Zeng, Y.; Zhou, C.; Zucchelli, S.; CDF Collaboration

    2014-06-01

    We report evidence for s-channel single-top-quark production in proton-antiproton collisions at center-of-mass energy √s =1.96 TeV using a data set that corresponds to an integrated luminosity of 9.4 fb-1 collected by the Collider Detector at Fermilab. We select events consistent with the s-channel process including two jets and one leptonically decaying W boson. The observed significance is 3.8 standard deviations with respect to the background-only prediction. Assuming a top-quark mass of 172.5 GeV /c2, we measure the s-channel cross section to be 1.41-0.42+0.44 pb.

  10. Flood Deposition Patterns and Channel Migration due to a 10-year flood event: the case of the Indus River flood 2010

    NASA Astrophysics Data System (ADS)

    Kettner, A. J.; Syvitski, J. P.; Overeem, I.; Brakenridge, G. R.

    2013-12-01

    Fluvial geomorphological processes evolve the landscape and are often referred to as processes that act for hundred to thousands of years before making a noticeable change in landforms. For the Indus River, landscape evolution has been intensified due to human interference. Failure in repairing its levees from previous floods led in July 2010 during a not exceptional discharge event (~10 year recurrence interval) to a large avulsion and flooding disaster that caused ~2,000 fatalities. Examining pre- and post flood maps by analyzing MODIS and ASTER-A1 data allowed us to determine the extent of sandy flood deposits and to quantify channel migration patterns. The typical pattern of inner bend deposition (due to helical flow) and outer bend erosion were less pronounced. We hypothesize that when flow exceeds bankfull conditions, deposition is more uniform and no longer constrained by the streambed geometry. We observe that the inner and the outer river bend receive similar amounts of sandy deposits (43% versus 57% respectively). Crevasse splaying was widespread and appeared to occur as a flow stripping process again both upon the point bars as well as in river outer bends. Channel activity (defined as the areal shift of the pre- and post river centerline), sinuosity, slope and lateral sediment deposition were determined for 50km river stretches. Analyzes reveal that flood deposits extend generally less than 2 km from the main channel axis. Furthermore, channel activity correlates negatively with channel sinuosity and lateral distance of sediment deposition and positively with slope. The river channel migrated over 100's of meters during the July 2010 flood event. Lateral migration averaged ~340m along a 1000km stretch of the Indus River over a period of just 52 days. Although this discharge event was not exceptional, lateral migration was significant and deposition impacts the active river floodplain. Remarkably, most sediments are deposited downstream the large

  11. Coupling effect analysis between landslides, river channel changes and sediment budgets - extreme climate events in Laishe River, southern Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, Kuo-Jen; Huang, Mei-Jen; Tseng, Chih-Ming

    2016-04-01

    amount of migration along Laishe River by analyzing the 3D DEM before and after the typhoon Morakot. The DEMs are built by using the aerial images taken by digital mapping camera (DMC) and by airborne digital scanner 40 (ADS40) before and after typhoon event. Recently, this research integrates Unmanned Aerial Vehicle (UAV) and oblique photogrammetric technologies for image acquisition by 5-10cm GSD photos. This approach permits to construct true 3D model so as to decipher ground information more realistically. 10-20cm DSM and DEM, and field GPS, were compiled together to decipher the morphologic changes. All the information, especially by means of true 3D model, the datasets provides detail ground information that may use to evaluate the landslide triggering mechanism and river channel evolution. The goals of this study is to integrates the UAS system and to decipher the sliding process and morphologic changes of large landslide areas, sediment transport and budgets, and to investigate the phenomenon of river migration. The results of this study provides not only geomatics and GIS dataset of the hazards, but also for essential geomorphologic information for other study, and for hazard mitigation and planning, as well.

  12. Coastal flooding events on the French coast of the eastern English Channel: the result of a combination of meteorological, marine, and morphological factors

    NASA Astrophysics Data System (ADS)

    Letortu, P.; Costa, S.; Cantat, O.; Levoy, F.; Dauvin, J. C.; De Saint-Léger, E.

    2012-04-01

    On account of increasing inhabitation and development of coastal areas, the economical stakes are high for forecasting and prevention of coastal flooding risk. Because of its exposure to prevailing Westerlies, morphological, and topographic features, low coastal areas on the French coast of the eastern English Channel are particularly sensitive to this natural risk. This sensitivity, that has always characterized this study area, is becoming worrying to politicians and inhabitants. The study aim is to identify, from 1949 to 2010, the possible increase of frequency and intensity of these meteorological and marine events, and their characteristics for forecasting objectives. The chosen approach is made up of three elements: 1) An analysis of strong west wind over the last decades has been implemented from Meteo-France data of Dieppe, reliable regional meteorological station. Beyond multi-annual random fluctuations, we have noticed a decrease in frequency and intensity of strong winds traditionally involved in flooding events. 2) An analysis of past events has been carried out from many information sources to warrant the accuracy of statements and their exhaustiveness. Thanks to this database, the main results are: i) the absence of increasing trend about frequency and intensity of coastal flooding events; ii) the cartography of coastal flooding risk for each urbanized area; iii) the definition of wind and tide level thresholds (7 m/s and 8.49 m at Dieppe) above which there is flooding. 3) A characterization, on the synoptic scale, of meteorological conditions ending in flooding has been performed. In matching this piece of information with the past events inventory, we have identified: firstly the two major types of low pressure trajectories that generated overflowing, so the two main atmospheric circulations prone to flooding, and secondly the fundamental meteorological aspect of the high north-west pressure gradient (≥ 20 hPa from "Pointe du Raz" (France) to

  13. A subtle alternative splicing event of the Na(V)1.8 voltage-gated sodium channel is conserved in human, rat, and mouse.

    PubMed

    Schirmeyer, Jana; Szafranski, Karol; Leipold, Enrico; Mawrin, Christian; Platzer, Matthias; Heinemann, Stefan H

    2010-06-01

    The voltage-gated sodium channel subtype Na(V)1.8 (SCN10A) is exclusively expressed in dorsal root ganglia (DRG) and plays a critical role in pain perception. We isolated mRNA from human, rat, and mouse DRGs and screened for alternatively spliced isoforms of the SCN10A mRNA using 454 sequencing. In all three species, we found an event of subtle alternative splicing at a NAGNAG tandem acceptor that results in isoforms including or lacking glutamine 1030 (Na(V)1.8+Q and Na(V)1.8-Q, respectively) within the cytoplasmic loop between domains II and III. The relative amount of Na(V)1.8-Q mRNA in adult DRG was measured with 14.1 +/- 0.1% in humans and 11.2 +/- 0.2% in rats. This is in contrast to an abundance of 64.3 +/- 0.3% in mouse DRG. Thus, the NAGNAG tandem acceptor in SCN10A is conserved among rodents and humans but its alternative usage apparently occurs with species-specific abundance. Analysis of human Na(V)1.8+Q and -Q isoforms in whole-cell patch-clamp experiments after heterologous expression in the neuroblastoma cell line Neuro-2A revealed no obvious impact of the splicing event on channel function. PMID:19953341

  14. Effects of fire and subsequent channel-reorganizing events on invertebrate drift and rainbow trout diet in small headwater streams 10 years post-disturbance

    NASA Astrophysics Data System (ADS)

    Rosenberger, A. E.; Dunham, J. B.; Wipfli, M. S.; Buffington, J. M.

    2005-05-01

    a greater terrestrial contribution in burned streams; while fish in unburned streams have a greater terrestrial component in their diet in the fall. Our results indicate that the effects of fire and disturbance on invertebrate communities are difficult to detect 10-years post event. Resilience in the invertebrate community and a flexible diet may be contributing to the resilience of resident trout found throughout our study streams. However, geomorphic changes and habitat alterations caused by massive channel-reorganizing events after wildfire may prevent full invertebrate community recovery for some time after the disturbance.

  15. The chemically homogeneous evolutionary channel for binary black hole mergers: rates and properties of gravitational-wave events detectable by advanced LIGO

    NASA Astrophysics Data System (ADS)

    de Mink, S. E.; Mandel, I.

    2016-08-01

    We explore the predictions for detectable gravitational-wave signals from merging binary black holes formed through chemically homogeneous evolution in massive short-period stellar binaries. We find that ˜500 events per year could be detected with advanced ground-based detectors operating at full sensitivity. We analyse the distribution of detectable events, and conclude that there is a very strong preference for detecting events with nearly equal components (mass ratio >0.66 at 90 per cent confidence in our default model) and high masses (total source-frame mass between 57 and 103 M⊙ at 90 per cent confidence). We consider multiple alternative variations to analyse the sensitivity to uncertainties in the evolutionary physics and cosmological parameters, and conclude that while the rates are sensitive to assumed variations, the mass distributions are robust predictions. Finally, we consider the recently reported results of the analysis of the first 16 double-coincident days of the O1 LIGO (Laser Interferometer Gravitational-wave Observatory) observing run, and find that this formation channel is fully consistent with the inferred parameters of the GW150914 binary black hole detection and the inferred merger rate.

  16. Modeling rates of bank erosion in sinuous tidal channel derived from event-based terrestrial lidar surveys in the Mont Saint Michel Bay

    NASA Astrophysics Data System (ADS)

    Leroux, J.; Lague, D.

    2012-12-01

    The Mont-Saint-Michel (MSM) bay is characterized by a semi-diurnal regime with a tidal range of 14 meter. Understanding river bank migration of tidal channels in such mega tidal salt marshes requires a precise quantification of the relative contribution of frequent and infrequent bank erosion events to the longer term dynamics. We use terrestrial lidar scanner (TLS) which overcomes the limitations of traditional bank measurement approaches (e.g. aerial photography, GPS measurements) with high resolution and high precision topographic data. We use 30 TLS measurements and traditional data sources to quantify the annual and daily dynamics of bank erosion for a sinuous salt marsh channel near the island of the MSM. We present the results of a 2 years study that begun in September 2010. We compare annual bank retreat with daily surveys focused on spring tides in order to calculate "event-based" volume of bank erosion. For active steep banks, the volume of sediment eroded is computed between 2 set of point cloud that are classified by the CANUPO algorithm to remove vegetation (Brodu and Lague, 2012). A new algorithm allows a direct comparison of point clouds in 3D based on surface normal computation and measurement of mean surface change along the normal direction. On a 5 centimeter resolution grid, the changes between 2 banks point cloud is computed and used to calculate volume of eroded bank. Measured rates of bank retreat varied between no detectable change to 2 m/tide, which correspond roughly to 100 cubic meters/tide. We also document a non-homothetic pattern of bank erosion during spring tides : erosion is focused in narrow zones of the meander and shifts spatially at daily timescales. To relate bank erosion to hydraulic characteristics of the channel, an ADCP was used to measure flow velocity during tides. The measurements highlights two main points that only occurs when tides overcomes the salt marsh: (i) the ebb flow is stronger than flood flow with velocities

  17. Measurement of the Forward-Backward Asymmetry in Top-Antitop Quark Events in the Lepton+Jets Channel at D0

    SciTech Connect

    Orbaker, Douglas Andrew

    2012-01-01

    We present a measurement of forward-backward asymmetries in top-antitop quark pairs produced in proton-antiproton collisions decaying via the lepton+jets channel. Using data recorded by the D0 experiment at the Fermilab Tevatron collider and corresponding to an integrated luminosity of 5.4 fb-1, we measure the forward-backward asymmetry in top-antitop quark events to be $\\left(9.2 \\pm 3.7\\right)\\%$, after background processes have been subtracted. After correcting for the effects of acceptance and detector reconstruction, we measure an asymmetry of $\\left(19.6 \\pm 6.5\\right)\\%$. In addition, we measure an acceptance-corrected asymmetry based on the lepton from top-antitop quark decay of $\\left(15.2 \\pm 4.0\\right)\\%$. We compare these results to predictions from the MC@NLO next-to-leading-order QCD simulation.

  18. Quantifying the in-channel retention of cohesive sediments during artificial flood events using FTIR-DRIFT spectrometry

    NASA Astrophysics Data System (ADS)

    Kurtenbach, A.; Gallé, T.; Buis, K.; de Sutter, R.; Troch, P.; Eisold, B.; Bierl, R.; Symader, W.

    2010-05-01

    Cohesive sediments control river ecosystem quality both as a transport medium for contaminants and as clogging material of stream bottom habitats. However, experimental field studies with fine-grained sediments in fluvial systems are rather scarce owing to the lack of adequate tracers and detection methods. As a result, current modelling approaches only insufficiently describe hydrodynamic transport and depositional behaviour of fine-grained sediments in rivers. We adopted two strategies to specifically study cohesive sediment dynamics in natural systems under defined boundary conditions. First, artificial floods were generated in the Olewiger Bach basin (24 km²), a mid-mountain gravel bed river, in order to characterise the in-channel fine sediment dynamics on their own. The advantage of these artificial flood waves lies in the selective control on some governing processes by experimental design. Second, fine sediment transport and deposition during these controlled reservoir releases were analysed by introducing the clay mineral kaolinite as a fine particle tracer, whose concentration was measured by Fourier transform infrared spectroscopy (FTIR) in diffuse reflectance mode (DRIFT). The DRIFT technique offers some important advantages such as the ability to assess both mineral and organic structures in aquatic particles, good sensitivity and high throughput (Gallé et al. 2004). Our laboratory tests confirm that FTIR-DRIFT spectrometry is capable of detecting the kaolinite tracer even in low percentage solid concentrations. The mass balance of the injected kaolinite for near bank-full artificial floods showed that, in spite of the very fine material and the non-stationary boundary conditions, over 50 percent of the tracer could be retained over a flow length of only 500 m. By combining fine particulate and natural dissolved tracers (e.g. dissolved organic carbon, DOC) we were able to identify the hyporheic zone as a potential short-term retention and storage

  19. Search for s-Channel Single-Top-Quark Production in Events with Missing Energy Plus Jets in pp ¯ Collisions at √s =1.96 TeV

    NASA Astrophysics Data System (ADS)

    Aaltonen, T.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D'Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Elagin, A.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucà, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Martínez, M.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Ranjan, N.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Vázquez, F.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Zanetti, A. M.; Zeng, Y.; Zhou, C.; Zucchelli, S.; CDF Collaboration

    2014-06-01

    The first search for single-top-quark production from the exchange of an s-channel virtual W boson using events with an imbalance in the total transverse energy, b-tagged jets, and no identified leptons is presented. Assuming the electroweak production of top quarks of mass 172.5 GeV /c2 in the s channel, a cross section of 1.12-0.57+0.61 (stat+syst) pb with a significance of 1.9 standard deviations is measured. This measurement is combined with the result obtained from events with an imbalance in total transverse momentum, b-tagged jets, and exactly one identified lepton, yielding a cross section of 1.36-0.32+0.37 (stat+syst) pb, with a significance of 4.2 standard deviations.

  20. Search for s-channel single-top-quark production in events with missing energy plus jets in pp collisions at sqrt[s] = 1.96 TeV.

    PubMed

    Aaltonen, T; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Butti, P; Buzatu, A; Calamba, A; Camarda, S; Campanelli, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Cho, K; Chokheli, D; Clark, A; Clarke, C; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Cremonesi, M; Cruz, D; Cuevas, J; Culbertson, R; d'Ascenzo, N; Datta, M; de Barbaro, P; Demortier, L; Deninno, M; D'Errico, M; Devoto, F; Di Canto, A; Di Ruzza, B; Dittmann, J R; Donati, S; D'Onofrio, M; Dorigo, M; Driutti, A; Ebina, K; Edgar, R; Elagin, A; Erbacher, R; Errede, S; Esham, B; Farrington, S; Fernández Ramos, J P; Field, R; Flanagan, G; Forrest, R; Franklin, M; Freeman, J C; Frisch, H; Funakoshi, Y; Galloni, C; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González López, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gramellini, E; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Han, J Y; Happacher, F; Hara, K; Hare, M; Harr, R F; Harrington-Taber, T; Hatakeyama, K; Hays, C; Heinrich, J; Herndon, M; Hocker, A; Hong, Z; Hopkins, W; Hou, S; Hughes, R E; Husemann, U; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kambeitz, M; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S H; Kim, S B; Kim, Y J; Kim, Y K; Kimura, N; Kirby, M; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Kruse, M; Kuhr, T; Kurata, M; Laasanen, A T; Lammel, S; Lancaster, M; Lannon, K; Latino, G; Lee, H S; Lee, J S; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lipeles, E; Lister, A; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucchesi, D; Lucà, A; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Marchese, L; Margaroli, F; Marino, P; Martínez, M; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M J; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Nigmanov, T; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagliarone, C; Palencia, E; Palni, P; Papadimitriou, V; Parker, W; Pauletta, G; Paulini, M; Paus, C; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Pranko, A; Prokoshin, F; Ptohos, F; Punzi, G; Ranjan, N; Redondo Fernández, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodriguez, T; Rolli, S; Ronzani, M; Roser, R; Rosner, J L; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, E E; Schwarz, T; Scodellaro, L; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sliwa, K; Smith, J R; Snider, F D; Song, H; Sorin, V; St Denis, R; Stancari, M; Stentz, D; Strologas, J; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thomson, E; Thukral, V; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Ukegawa, F; Uozumi, S; Velev, G; Vellidis, C; Vernieri, C; Vidal, M; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Vázquez, F; Wagner, P; Wallny, R; Wang, S M; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wilbur, S; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Zanetti, A M; Zeng, Y; Zhou, C; Zucchelli, S

    2014-06-13

    The first search for single-top-quark production from the exchange of an s-channel virtual W boson using events with an imbalance in the total transverse energy, b-tagged jets, and no identified leptons is presented. Assuming the electroweak production of top quarks of mass 172.5 GeV/c(2) in the s channel, a cross section of 1.12(-0.57)(+0.61) (stat+syst) pb with a significance of 1.9 standard deviations is measured. This measurement is combined with the result obtained from events with an imbalance in total transverse momentum, b-tagged jets, and exactly one identified lepton, yielding a cross section of 1.36(-0.32)(+0.37) (stat+syst) pb, with a significance of 4.2 standard deviations.

  1. An angiotensin II receptor blocker–calcium channel blocker combination prevents cardiovascular events in elderly high-risk hypertensive patients with chronic kidney disease better than high-dose angiotensin II receptor blockade alone

    PubMed Central

    Kim-Mitsuyama, Shokei; Ogawa, Hisao; Matsui, Kunihiko; Jinnouchi, Tomio; Jinnouchi, Hideaki; Arakawa, Kikuo

    2013-01-01

    The OSCAR study was a multicenter, prospective randomized open-label blinded end-point study of 1164 Japanese elderly hypertensive patients comparing the efficacy of angiotensin II receptor blocker (ARB) uptitration to an ARB plus calcium channel blocker (CCB) combination. In this prospective study, we performed prespecified subgroup analysis according to baseline estimated glomerular filtration rate (eGFR) with chronic kidney disease (CKD) defined as an eGFR <60 ml/min per 1.73 m2. Blood pressure was lower in the combined therapy than in the high-dose ARB cohort in both groups with and without CKD. In patients with CKD, significantly more primary events (a composite of cardiovascular events and noncardiovascular death) occurred in the high-dose ARB group than in the combination group (30 vs. 16, respectively, hazard ratio 2.25). Significantly more cerebrovascular and more heart failure events occurred in the high-dose ARB group than in the combination group. In patients without CKD, however, the incidence of primary events was similar between the two treatments. The treatment-by-subgroup interaction was significant. Allocation to the high-dose ARB was a significant independent prognostic factor for primary events in patients with CKD. Thus, the ARB plus CCB combination conferred greater benefit in prevention of cardiovascular events in patients with CKD compared with high-dose ARB alone. Our findings provide new insight into the antihypertensive strategy for elderly hypertensive patients with CKD. PMID:23051740

  2. Sediment budget analysis from Landslide debris and river channel change during the extreme event - example of Typhoon Morakot at Laonong river, Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, Kuo-Jen; Huang, Yu-Ting; Huang, Mei-Jen; Chiang, Yi-Lin; Yeh, En-Chao; Chao, Yu-Jui

    2014-05-01

    Taiwan, due to the high seismicity and high annual rainfall, numerous landslides triggered every year and severe impacts affect the island. Typhoon Morakot brought extreme and long-time rainfall for Taiwan in August 2009. It further caused huge loss of life and property in central and southern Taiwan. Laonong River is the largest tributary of Gaoping River. It's length is 137 km, and the basin area is 1373 km2. More than 2000mm rainfall brought and maximum rainfall exceeded 100mm/hr in the region by Typhoon Morakot in Aug, 2009. Its heavy rains made many landslides and debris flew into the river and further brought out accumulation and erosion on river banks of different areas. It caused severe disasters within the Laonong River drainage. In the past, the study of sediment blockage of river channel usually relies on field investigation, but due to inconvenient transportation, topographical barriers, or located in remote areas, etc. the survey is hardly to be completed sometimes. In recent years, the rapid development of remote sensing technology improves image resolution and quality significantly. Remote sensing technology can provide a wide range of image data, and provide essential and precious information. Furthermore, although the amount of sediment transportation can be estimated by using data such as rainfall, river flux, and suspended loads, the situation of large debris migration cannot be studied via those data. However, landslides, debris flow and river sediment transportation model in catchment area can be evaluated easily through analyzing the digital terrain model (DTM) . The purpose of this study is to investigate the phenomenon of river migration and to evaluate the amount of migration along Laonong River by analyzing the DEM before and after the typhoon Morakot. The DEMs are built by using the aerial images taken by digital mapping camera (DMC) and by airborne digital scanner 40 (ADS 40) before and after typhoon event. The results show that lateral

  3. Preprocessing by a Bayesian Single-Trial Event-Related Potential Estimation Technique Allows Feasibility of an Assistive Single-Channel P300-Based Brain-Computer Interface

    PubMed Central

    Goljahani, Anahita; D'Avanzo, Costanza; Silvoni, Stefano; Tonin, Paolo; Piccione, Francesco; Sparacino, Giovanni

    2014-01-01

    A major clinical goal of brain-computer interfaces (BCIs) is to allow severely paralyzed patients to communicate their needs and thoughts during their everyday lives. Among others, P300-based BCIs, which resort to EEG measurements, have been successfully operated by people with severe neuromuscular disabilities. Besides reducing the number of stimuli repetitions needed to detect the P300, a current challenge in P300-based BCI research is the simplification of system's setup and maintenance by lowering the number N of recording channels. By using offline data collected in 30 subjects (21 amyotrophic lateral sclerosis patients and 9 controls) through a clinical BCI with N = 5 channels, in the present paper we show that a preprocessing approach based on a Bayesian single-trial ERP estimation technique allows reducing N to 1 without affecting the system's accuracy. The potentially great benefit for the practical usability of BCI devices (including patient acceptance) that would be given by the reduction of the number N of channels encourages further development of the present study, for example, in an online setting. PMID:25104969

  4. Calcium Channel Signaling Complexes with Receptors and Channels.

    PubMed

    Zamponi, Gerald W

    2015-01-01

    Voltage-gated calcium channels are not only mediators of cell signalling events, but also are recipients of signalling inputs from G protein coupled receptors (GPCRs) and their associated second messenger pathways. The coupling of GPCRs to calcium channels is optimized through the formation of receptor-channel complexes. In addition, this provides a mechanism for receptorchannel co-trafficking to and from the plasma membrane. On the other hand, voltage-gated calcium channel activity affects other types of ion channels such as voltage-and calcium-activated potassium channels. Coupling efficiency between these two families of channels is also enhanced through the formation of channel-channel complexes. This review provides a concise overview of the current state of knowledge on the physical interactions between voltage-gated calcium channels and members of the GPCR family, and with other types of ion channels.

  5. Microelectrode Arrays of Diamond-Insulated Graphitic Channels for Real-Time Detection of Exocytotic Events from Cultured Chromaffin Cells and Slices of Adrenal Glands.

    PubMed

    Picollo, Federico; Battiato, Alfio; Bernardi, Ettore; Marcantoni, Andrea; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2016-08-01

    A microstructured graphitic 4 × 4 multielectrode array was embedded in a single-crystal diamond substrate (4 × 4 μG-SCD MEA) for real-time monitoring of exocytotic events from cultured chromaffin cells and adrenal slices. The current approach relies on the development of a parallel ion beam lithographic technique, which assures the time-effective fabrication of extended arrays with reproducible electrode dimensions. The reported device is suitable for performing amperometric and voltammetric recordings with high sensitivity and temporal resolution, by simultaneously acquiring data from 16 rectangularly shaped microelectrodes (20 × 3.5 μm(2)) separated by 200 μm gaps. Taking advantage of the array geometry we addressed the following specific issues: (i) detect both the spontaneous and KCl-evoked secretion simultaneously from several chromaffin cells directly cultured on the device surface, (ii) resolve the waveform of different subsets of exocytotic events, and (iii) monitoring quantal secretory events from thin slices of the adrenal gland. The frequency of spontaneous release was low (0.12 and 0.3 Hz, respectively, for adrenal slices and cultured cells) and increased up to 0.9 Hz after stimulation with 30 mM KCl in cultured cells. The spike amplitude as well as rise and decay time were comparable with those measured by carbon fiber microelectrodes and allowed to identify three different subsets of secretory events associated with "full fusion" events, "kiss-and-run" and "kiss-and-stay" exocytosis, confirming that the device has adequate sensitivity and time resolution for real-time recordings. The device offers the significant advantage of shortening the time to collect data by allowing simultaneous recordings from cell populations either in primary cell cultures or in intact tissues. PMID:27376596

  6. Microelectrode Arrays of Diamond-Insulated Graphitic Channels for Real-Time Detection of Exocytotic Events from Cultured Chromaffin Cells and Slices of Adrenal Glands.

    PubMed

    Picollo, Federico; Battiato, Alfio; Bernardi, Ettore; Marcantoni, Andrea; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2016-08-01

    A microstructured graphitic 4 × 4 multielectrode array was embedded in a single-crystal diamond substrate (4 × 4 μG-SCD MEA) for real-time monitoring of exocytotic events from cultured chromaffin cells and adrenal slices. The current approach relies on the development of a parallel ion beam lithographic technique, which assures the time-effective fabrication of extended arrays with reproducible electrode dimensions. The reported device is suitable for performing amperometric and voltammetric recordings with high sensitivity and temporal resolution, by simultaneously acquiring data from 16 rectangularly shaped microelectrodes (20 × 3.5 μm(2)) separated by 200 μm gaps. Taking advantage of the array geometry we addressed the following specific issues: (i) detect both the spontaneous and KCl-evoked secretion simultaneously from several chromaffin cells directly cultured on the device surface, (ii) resolve the waveform of different subsets of exocytotic events, and (iii) monitoring quantal secretory events from thin slices of the adrenal gland. The frequency of spontaneous release was low (0.12 and 0.3 Hz, respectively, for adrenal slices and cultured cells) and increased up to 0.9 Hz after stimulation with 30 mM KCl in cultured cells. The spike amplitude as well as rise and decay time were comparable with those measured by carbon fiber microelectrodes and allowed to identify three different subsets of secretory events associated with "full fusion" events, "kiss-and-run" and "kiss-and-stay" exocytosis, confirming that the device has adequate sensitivity and time resolution for real-time recordings. The device offers the significant advantage of shortening the time to collect data by allowing simultaneous recordings from cell populations either in primary cell cultures or in intact tissues.

  7. TRP Channels

    NASA Astrophysics Data System (ADS)

    Voets, Thomas; Owsianik, Grzegorz; Nilius, Bernd

    The TRP superfamily represents a highly diverse group of cation-permeable ion channels related to the product of the Drosophila trp (transient receptor potential) gene. The cloning and characterization of members of this cation channel family has experienced a remarkable growth during the last decade, uncovering a wealth of information concerning the role of TRP channels in a variety of cell types, tissues, and species. Initially, TRP channels were mainly considered as phospholipase C (PLC)-dependent and/or store-operated Ca2+-permeable cation channels. More recent research has highlighted the sensitivity of TRP channels to a broad array of chemical and physical stimuli, allowing them to function as dedicated biological sensors involved in processes ranging from vision to taste, tactile sensation, and hearing. Moreover, the tailored selectivity of certain TRP channels enables them to play key roles in the cellular uptake and/or transepithelial transport of Ca2+, Mg2+, and trace metal ions. In this chapter we give a brief overview of the TRP channel superfamily followed by a survey of current knowledge concerning their structure and activation mechanisms.

  8. Clinical events in high-risk hypertensive patients randomly assigned to calcium channel blocker versus angiotensin-converting enzyme inhibitor in the antihypertensive and lipid-lowering treatment to prevent heart attack trial.

    PubMed

    Leenen, Frans H H; Nwachuku, Chuke E; Black, Henry R; Cushman, William C; Davis, Barry R; Simpson, Lara M; Alderman, Michael H; Atlas, Steven A; Basile, Jan N; Cuyjet, Aloysius B; Dart, Richard; Felicetta, James V; Grimm, Richard H; Haywood, L Julian; Jafri, Syed Z A; Proschan, Michael A; Thadani, Udho; Whelton, Paul K; Wright, Jackson T

    2006-09-01

    The Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT) provides a unique opportunity to compare the long-term relative safety and efficacy of angiotensin-converting enzyme inhibitor and calcium channel blocker-initiated therapy in older hypertensive individuals. Patients were randomized to amlodipine (n=9048) or lisinopril (n=9054). The primary outcome was combined fatal coronary heart disease or nonfatal myocardial infarction, analyzed by intention-to-treat. Secondary outcomes included all-cause mortality, stroke, combined cardiovascular disease (CVD), end-stage renal disease (ESRD), cancer, and gastrointestinal bleeding. Mean follow-up was 4.9 years. Blood pressure control was similar in nonblacks, but not in blacks. No significant differences were found between treatment groups for the primary outcome, all-cause mortality, ESRD, or cancer. Stroke rates were higher on lisinopril in blacks (RR=1.51, 95% CI 1.22 to 1.86) but not in nonblacks (RR=1.07, 95% CI 0.89 to 1.28), and in women (RR=1.45, 95% CI 1.17 to 1.79), but not in men (RR=1.10, 95% CI 0.92 to 1.31). Rates of combined CVD were higher (RR=1.06, 95% CI 1.00 to 1.12) because of higher rates for strokes, peripheral arterial disease, and angina, which were partly offset by lower rates for heart failure (RR=0.87, 95% CI 0.78 to 0.96) on lisinopril compared with amlodipine. Gastrointestinal bleeds and angioedema were higher on lisinopril. Patients with and without baseline coronary heart disease showed similar outcome patterns. We conclude that in hypertensive patients, the risks for coronary events are similar, but for stroke, combined CVD, gastrointestinal bleeding, and angioedema are higher and for heart failure are lower for lisinopril-based compared with amlodipine-based therapy. Some, but not all, of these differences may be explained by less effective blood pressure control in the lisinopril arm.

  9. English Channel

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The cloud covered earthscape of Northern Europe demonstrates the difficulty of photographing this elusive subject from space. The English Channel (51.0N, 1.5E) separating the British Islands from Europe is in the center of the scene. The white cliffs of Dover on the SE coast of the UK, the Thames River estuary and a partial view of the city of London can be seen on the north side of the Channel while the Normandy coast of France is to the south.

  10. [The depth distribution of neutron-capture events in 10B nuclei during the irradiation of a water phantom with neutrons from the channels of the BR-10 reactor].

    PubMed

    Kapchigashev, S P; Potetnia, V I; Khodyreva, E V; Neshina, V S

    1991-01-01

    The authors present the results of experimental investigations of distribution of capture events on nuclei 10B by the depth of a water phantom during its irradiation with beams T-4 and B-3 of the BR-10 reactor. A ferrous sulfate dosimeter with added boric acid was used as a detector of such events. The depth of a water phantom on which the effect of boron capture by a neutron beam is decreased 2-fold, is 1.7 cm. For the B-3 beam a curve of depth correlation of neutron capture events had a broad maximum at a depth of 4-5 cm.

  11. The channels of Mars

    NASA Technical Reports Server (NTRS)

    Baker, Victor R.

    1988-01-01

    The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

  12. Nonlinear channelizer.

    PubMed

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D; Leung, Daniel; Liu, Norman; Meadows, Brian K; Gordon, Frank; Bulsara, Adi R; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  13. Safeguards Summary Event List (SSEL)

    SciTech Connect

    Not Available

    1991-07-01

    The Safeguards Summary Event List (SSEL) provides brief summaries of several hundred safeguards-related events involving nuclear material or facilities regulated by the US Nuclear Regulatory Commission (NRC). Because of public interest, the Miscellaneous category includes a few events which involve either source material, byproduct material, or natural uranium which are exempt from safeguards requirements. Events are described under the categories of bomb-related, intrusion, missing and/or allegedly stolen, transportation, tampering/vandalism, arson, firearms, radiological sabotage, nonradiological sabotage, pre-1990 alcohol and drugs (involving reactor operators, security force members, or management persons), and miscellaneous. The information contained in the event descriptions is derived primarily from official NRC reporting channels.

  14. Transformational Events

    ERIC Educational Resources Information Center

    Denning, Peter J.; Hiles, John E.

    2006-01-01

    Transformational Events is a new pedagogic pattern that explains how innovations (and other transformations) happened. The pattern is three temporal stages: an interval of increasingly unsatisfactory ad hoc solutions to a persistent problem (the "mess"), an offer of an invention or of a new way of thinking, and a period of widespread adoption and…

  15. Maintenance Event

    Atmospheric Science Data Center

    2014-07-22

    Time:  08:00 am - 08:30 am EDT Event Impact:  Science Directorate websites will ... outage Thursday morning, 7/24, to perform upgrades to the web environment and are expected to be down for about 30 minutes. ...

  16. Turbulent supersonic channel flow

    NASA Astrophysics Data System (ADS)

    Lechner, Richard; Sesterhenn, Jörn; Friedrich, Rainer

    2001-01-01

    The effects of compressibility are studied in low Reynolds number turbulent supersonic channel flow via a direct numerical simulation. A pressure-velocity-entropy formulation of the compressible Navier-Stokes equations which is cast in a characteristic, non-conservative form and allows one to specify exact wall boundary conditions, consistent with the field equations, is integrated using a fifth-order compact upwind scheme for the Euler part, a fourth-order Padé scheme for the viscous terms and a third-order low-storage Runge-Kutta time integration method. Coleman et al fully developed supersonic channel flow at M?=?1.5 and Re?=?3000 is used to test the method. The nature of fluctuating variables is investigated in detail for the wall layer and the core region based on scatter plots. Fluctuations conditioned on sweeps and ejections in the wall layer are especially instructive, showing that positive temperature, entropy and total temperature fluctuations are mainly due to sweep events in this specific situation of wall cooling. The effect of compressibility on the turbulence structure is in many respects similar to that found in homogeneous shear turbulence and in mixing layers. The normal components of the Reynolds stress anisotropy tensor are increased due to compressibility, while the shear stress component is slightly reduced. Characteristic of the Reynolds stress transport is a suppression of the production of the longitudinal and the shear stress component, a suppression of all velocity-pressure-gradient correlations and most of the dissipation rates. Comparison with incompressible channel flow data reveals that compressibility effects manifest themselves in the wall layer only.

  17. Transient Receptor Potential Channels in the Vasculature

    PubMed Central

    Earley, Scott; Brayden, Joseph E.

    2015-01-01

    The mammalian genome encodes 28 distinct members of the transient receptor potential (TRP) superfamily of cation channels, which exhibit varying degrees of selectivity for different ionic species. Multiple TRP channels are present in all cells and are involved in diverse aspects of cellular function, including sensory perception and signal transduction. Notably, TRP channels are involved in regulating vascular function and pathophysiology, the focus of this review. TRP channels in vascular smooth muscle cells participate in regulating contractility and proliferation, whereas endothelial TRP channel activity is an important contributor to endothelium-dependent vasodilation, vascular wall permeability, and angiogenesis. TRP channels are also present in perivascular sensory neurons and astrocytic endfeet proximal to cerebral arterioles, where they participate in the regulation of vascular tone. Almost all of these functions are mediated by changes in global intracellular Ca2+ levels or subcellular Ca2+ signaling events. In addition to directly mediating Ca2+ entry, TRP channels influence intracellular Ca2+ dynamics through membrane depolarization associated with the influx of cations or through receptor- or store-operated mechanisms. Dysregulation of TRP channels is associated with vascular-related pathologies, including hypertension, neointimal injury, ischemia-reperfusion injury, pulmonary edema, and neurogenic inflammation. In this review, we briefly consider general aspects of TRP channel biology and provide an in-depth discussion of the functions of TRP channels in vascular smooth muscle cells, endothelial cells, and perivascular cells under normal and pathophysiological conditions. PMID:25834234

  18. Active channel for Fanno Creek, Oregon

    USGS Publications Warehouse

    Sobieszczyk, Steven

    2011-01-01

    Fanno Creek is a tributary to the Tualatin River and flows though parts of the southwest Portland metropolitan area. The stream is heavily influenced by urban runoff and shows characteristic flashy streamflow and poor water quality commonly associated with urban streams. This data set represents the active, wetted channel as derived from light detection and ranging (LiDAR) data and aerial photographic imagery. The wetted channel boundary is equivalent to the extent of water observed during a 2-yr high flow event.

  19. Events diary

    NASA Astrophysics Data System (ADS)

    2000-01-01

    as Imperial College, the Royal Albert Hall, the Royal College of Art, the Natural History and Science Museums and the Royal Geographical Society. Under the heading `Shaping the future together' BA2000 will explore science, engineering and technology in their wider cultural context. Further information about this event on 6 - 12 September may be obtained from Sandra Koura, BA2000 Festival Manager, British Association for the Advancement of Science, 23 Savile Row, London W1X 2NB (tel: 0171 973 3075, e-mail: sandra.koura@britassoc.org.uk ). Details of the creating SPARKS events may be obtained from creating.sparks@britassoc.org.uk or from the website www.britassoc.org.uk . Other events 3 - 7 July, Porto Alegre, Brazil VII Interamerican conference on physics education: The preparation of physicists and physics teachers in contemporary society. Info: IACPE7@if.ufrgs.br or cabbat1.cnea.gov.ar/iacpe/iacpei.htm 27 August - 1 September, Barcelona, Spain GIREP conference: Physics teacher education beyond 2000. Info: www.blues.uab.es/phyteb/index.html

  20. Serial data transmission between redundant channels

    NASA Technical Reports Server (NTRS)

    Tulpule, Bhalchandra R. (Inventor); Binnall, Daniel G. (Inventor)

    1992-01-01

    Data is communicated between redundant channels formatted in blocks having an initial command word followed by a destination code, starting address and a variable number of data words including a word count. The blocks are transmitted between each channel and all of the channels over cross-channel data links, each channel receiving the data blocks and determining the validity thereof by counting the number of data words received and comparing that number to the word count transmitted for that block. An interrupt signal indicative of invalidity of a block is provided in the event of a miscompare. A stop address is generated for each block received for storage at the start address. A memory address is generated for each valid word received for storage in sequence starting immediately after the start address. The next block received has its start address placed immediately at the end of the previously received block.

  1. Equalization in redundant channels

    NASA Technical Reports Server (NTRS)

    Tulpule, Bhalchandra R. (Inventor); Collins, Robert E. (Inventor); Cominelli, Donald F. (Inventor); O'Neill, Richard D. (Inventor)

    1988-01-01

    A miscomparison between a channel's configuration data base and a voted system configuration data base in a redundant channel system having identically operating, frame synchronous channels triggers autoequalization of the channel's historical signal data bases in a hierarchical, chronological manner with that of a correctly operating channel. After equalization, symmetrization of the channel's configuration data base with that of the system permits upgrading of the previously degraded channel to full redundancy. An externally provided equalization command, e.g., manually actuated, can also trigger equalization.

  2. Channel nut tool

    DOEpatents

    Olson, Marvin

    2016-01-12

    A method, system, and apparatus for installing channel nuts includes a shank, a handle formed on a first end of a shank, and an end piece with a threaded shaft configured to receive a channel nut formed on the second end of the shaft. The tool can be used to insert or remove a channel nut in a channel framing system and then removed from the channel nut.

  3. Age of Martian channels

    NASA Technical Reports Server (NTRS)

    Malin, M. C.

    1976-01-01

    The ages of large Martian channels have been studied by determining the relative abundances of craters superimposed on channels and adjacent terrains and by examining superposition relationships between channels and plains and mantle materials. The channels are extremely old, are spatially confined and temporally related to the ancient cratered terrain, and in many cases are related to the as yet poorly understood genetic processes of fretting and chaos formation. No evidence is found for recent channel activity.

  4. New observations of sinuous channels on the Amazon Fan

    NASA Astrophysics Data System (ADS)

    Flood, R. D.

    2014-12-01

    sudden changes in the planform shape of meanders farther down the channel. Thus while similarities in sinuosity patterns suggest that both submarine channels and river channels are being altered by repetitive flow events, channel-wall slumping in submarine channels may affect submarine channel evolution to a greater extent than similar events in rivers.

  5. Store-Operated Calcium Channels

    PubMed Central

    Lewis, Richard S.

    2015-01-01

    Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca2+ from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca2+ sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca2+ from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca2+ depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease. PMID:26400989

  6. Microfluidic channel fabrication method

    DOEpatents

    Arnold, Don W.; Schoeniger, Joseph S.; Cardinale, Gregory F.

    2001-01-01

    A new channel structure for microfluidic systems and process for fabricating this structure. In contrast to the conventional practice of fabricating fluid channels as trenches or grooves in a substrate, fluid channels are fabricated as thin walled raised structures on a substrate. Microfluidic devices produced in accordance with the invention are a hybrid assembly generally consisting of three layers: 1) a substrate that can or cannot be an electrical insulator; 2) a middle layer, that is an electrically conducting material and preferably silicon, forms the channel walls whose height defines the channel height, joined to and extending from the substrate; and 3) a top layer, joined to the top of the channels, that forms a cover for the channels. The channels can be defined by photolithographic techniques and are produced by etching away the material around the channel walls.

  7. Gramicidin Channels: Versatile Tools

    NASA Astrophysics Data System (ADS)

    Andersen, Olaf S.; Koeppe, Roger E., II; Roux, Benoît

    Gramicidin channels are miniproteins in which two tryptophan-rich subunits associate by means of transbilayer dimerization to form the conducting channels. That is, in contrast to other ion channels, gramicidin channels do not open and close; they appear and disappear. Each subunit in the bilayer-spanning channel is tied to the bilayer/solution interface through hydrogen bonds that involve the indole NH groups as donors andwater or the phospholipid backbone as acceptors. The channel's permeability characteristics are well-defined: gramicidin channels are selective for monovalent cations, with no measurable permeability to anions or polyvalent cations; ions and water move through a pore whose wall is formed by the peptide backbone; and the single-channel conductance and cation selectivity vary when the amino acid sequence is varied, even though the permeating ions make no contact with the amino acid side chains. Given the plethora of available experimental information—for not only the wild-type channels but also for channels formed by amino acid-substituted gramicidin analogues—gramicidin channels continue to provide important insights into the microphysics of ion permeation through bilayer-spanning channels. For similar reasons, gramicidin channels constitute a system of choice for evaluating computational strategies for obtaining mechanistic insights into ion permeation through the more complex channels formed by integral membrane proteins.

  8. Modulation of Potassium Channels Inhibits Bunyavirus Infection*

    PubMed Central

    Hover, Samantha; King, Barnabas; Hall, Bradley; Loundras, Eleni-Anna; Taqi, Hussah; Daly, Janet; Dallas, Mark; Peers, Chris; Schnettler, Esther; McKimmie, Clive; Kohl, Alain; Barr, John N.; Mankouri, Jamel

    2016-01-01

    Bunyaviruses are considered to be emerging pathogens facilitated by the segmented nature of their genome that allows reassortment between different species to generate novel viruses with altered pathogenicity. Bunyaviruses are transmitted via a diverse range of arthropod vectors, as well as rodents, and have established a global disease range with massive importance in healthcare, animal welfare, and economics. There are no vaccines or anti-viral therapies available to treat human bunyavirus infections and so development of new anti-viral strategies is urgently required. Bunyamwera virus (BUNV; genus Orthobunyavirus) is the model bunyavirus, sharing aspects of its molecular and cellular biology with all Bunyaviridae family members. Here, we show for the first time that BUNV activates and requires cellular potassium (K+) channels to infect cells. Time of addition assays using K+ channel modulating agents demonstrated that K+ channel function is critical to events shortly after virus entry but prior to viral RNA synthesis/replication. A similar K+ channel dependence was identified for other bunyaviruses namely Schmallenberg virus (Orthobunyavirus) as well as the more distantly related Hazara virus (Nairovirus). Using a rational pharmacological screening regimen, two-pore domain K+ channels (K2P) were identified as the K+ channel family mediating BUNV K+ channel dependence. As several K2P channel modulators are currently in clinical use, our work suggests they may represent a new and safe drug class for the treatment of potentially lethal bunyavirus disease. PMID:26677217

  9. Modulation of Potassium Channels Inhibits Bunyavirus Infection.

    PubMed

    Hover, Samantha; King, Barnabas; Hall, Bradley; Loundras, Eleni-Anna; Taqi, Hussah; Daly, Janet; Dallas, Mark; Peers, Chris; Schnettler, Esther; McKimmie, Clive; Kohl, Alain; Barr, John N; Mankouri, Jamel

    2016-02-12

    Bunyaviruses are considered to be emerging pathogens facilitated by the segmented nature of their genome that allows reassortment between different species to generate novel viruses with altered pathogenicity. Bunyaviruses are transmitted via a diverse range of arthropod vectors, as well as rodents, and have established a global disease range with massive importance in healthcare, animal welfare, and economics. There are no vaccines or anti-viral therapies available to treat human bunyavirus infections and so development of new anti-viral strategies is urgently required. Bunyamwera virus (BUNV; genus Orthobunyavirus) is the model bunyavirus, sharing aspects of its molecular and cellular biology with all Bunyaviridae family members. Here, we show for the first time that BUNV activates and requires cellular potassium (K(+)) channels to infect cells. Time of addition assays using K(+) channel modulating agents demonstrated that K(+) channel function is critical to events shortly after virus entry but prior to viral RNA synthesis/replication. A similar K(+) channel dependence was identified for other bunyaviruses namely Schmallenberg virus (Orthobunyavirus) as well as the more distantly related Hazara virus (Nairovirus). Using a rational pharmacological screening regimen, two-pore domain K(+) channels (K2P) were identified as the K(+) channel family mediating BUNV K(+) channel dependence. As several K2P channel modulators are currently in clinical use, our work suggests they may represent a new and safe drug class for the treatment of potentially lethal bunyavirus disease.

  10. Cholesterol and Ion Channels

    PubMed Central

    Levitan, Irena; Fang, Yun; Rosenhouse-Dantsker, Avia; Romanenko, Victor

    2010-01-01

    A variety of ion channels, including members of all major ion channel families, have been shown to be regulated by changes in the level of membrane cholesterol and partition into cholesterol-rich membrane domains. In general, several types of cholesterol effects have been described. The most common effect is suppression of channel activity by an increase in membrane cholesterol, an effect that was described for several types of inwardly-rectifying K+ channels, voltage-gated K+ channels, Ca+2 sensitive K+ channels, voltage-gated Na+ channels, N-type voltage-gated Ca+2 channels and volume-regulated anion channels. In contrast, several types of ion channels, such as epithelial amiloride-sensitive Na+ channels and Transient Receptor Potential channels, as well as some of the types of inwardly-rectifying and voltage-gated K+ channels were shown to be inhibited by cholesterol depletion. Cholesterol was also shown to alter the kinetic properties and current-voltage dependence of several voltage-gated channels. Finally, maintaining membrane cholesterol level is required for coupling ion channels to signalling cascades. In terms of the mechanisms, three general mechanisms have been proposed: (i) specific interactions between cholesterol and the channel protein, (ii) changes in the physical properties of the membrane bilayer and (iii) maintaining the scaffolds for protein-protein interactions. The goal of this review is to describe systematically the role of cholesterol in regulation of the major types of ion channels and to discuss these effects in the context of the models proposed. PMID:20213557

  11. Fading channel simulator

    SciTech Connect

    Argo, P.E.; Fitzgerald, T.J.

    1991-12-31

    This invention relates to high frequency (HF) radio signal propagation through fading channels and, more particularly, to simulation of fading channels in order to characterize HF radio system performance in transmitting and receiving signals through such fading channels. Fading channel effects on a transmitted communication signal are simulated with both frequency and time variations using a channel scattering function to affect the transmitted signal. A conventional channel scattering function is converted to a series of channel realizations by multiplying the square root of the channel scattering function by a complex number of which the real and imaginary parts are each independent variables. The two-dimensional inverse-FFT of this complex-valued channel realization yields a matrix of channel coefficients that provide a complete frequency-time description of the channel. The transmitted radio signal is segmented to provide a series of transmitted signal and each segment is subject to FFT to generate a series of signal coefficient matrices. The channel coefficient matrices and signal coefficient matrices are then multiplied and subjected to inverse-FFT to output a signal representing the received affected radio signal. A variety of channel scattering functions can be used to characterize the response of a transmitter-receiver system to such atmospheric effects.

  12. A CORBA event system for ALMA common software

    NASA Astrophysics Data System (ADS)

    Fugate, David W.

    2004-09-01

    The ALMA Common Software notification channel framework provides developers with an easy to use, high-performance, event-driven system supported across multiple programming languages and operating systems. It sits on top of the CORBA notification service and hides nearly all CORBA from developers. The system is based on a push event channel model where suppliers push events onto the channel and consumers process these asynchronously. This is a many-to-many publishing model whereby multiple suppliers send events to multiple consumers on the same channel. Furthermore, these event suppliers and consumers can be coded in C++, Java, or Python on any platform supported by ACS. There are only two classes developers need to be concerned with: SimpleSupplier and Consumer. SimpleSupplier was designed so that ALMA events (defined as IDL structures) could be published in the simplest manner possible without exposing any CORBA to the developer. Essentially all that needs to be known is the channel's name and the IDL structure being published. The API takes care of everything else. With the Consumer class, the developer is responsible for providing the channel's name as well as associating event types with functions that will handle them.

  13. Optimal channels for channelized quadratic estimators.

    PubMed

    Kupinski, Meredith K; Clarkson, Eric

    2016-06-01

    We present a new method for computing optimized channels for estimation tasks that is feasible for high-dimensional image data. Maximum-likelihood (ML) parameter estimates are challenging to compute from high-dimensional likelihoods. The dimensionality reduction from M measurements to L channels is a critical advantage of channelized quadratic estimators (CQEs), since estimating likelihood moments from channelized data requires smaller sample sizes and inverting a smaller covariance matrix is easier. The channelized likelihood is then used to form ML estimates of the parameter(s). In this work we choose an imaging example in which the second-order statistics of the image data depend upon the parameter of interest: the correlation length. Correlation lengths are used to approximate background textures in many imaging applications, and in these cases an estimate of the correlation length is useful for pre-whitening. In a simulation study we compare the estimation performance, as measured by the root-mean-squared error (RMSE), of correlation length estimates from CQE and power spectral density (PSD) distribution fitting. To abide by the assumptions of the PSD method we simulate an ergodic, isotropic, stationary, and zero-mean random process. These assumptions are not part of the CQE formalism. The CQE method assumes a Gaussian channelized likelihood that can be a valid for non-Gaussian image data, since the channel outputs are formed from weighted sums of the image elements. We have shown that, for three or more channels, the RMSE of CQE estimates of correlation length is lower than conventional PSD estimates. We also show that computing CQE by using a standard nonlinear optimization method produces channels that yield RMSE within 2% of the analytic optimum. CQE estimates of anisotropic correlation length estimation are reported to demonstrate this technique on a two-parameter estimation problem. PMID:27409452

  14. Ion channels and cancer.

    PubMed

    Kunzelmann, Karl

    2005-06-01

    Membrane ion channels are essential for cell proliferation and appear to have a role in the development of cancer. This has initially been demonstrated for potassium channels and is meanwhile also suggested for other cation channels and Cl- channels. For some of these channels, like voltage-gated ether à go-go and Ca2+-dependent potassium channels as well as calcium and chloride channels, a cell cycle-dependent function has been demonstrated. Along with other membrane conductances, these channels control the membrane voltage and Ca2+ signaling in proliferating cells. Homeostatic parameters, such as the intracellular ion concentration, cytosolic pH and cell volume, are also governed by the activity of ion channels. Thus it will be an essential task for future studies to unravel cell cycle-specific effects of ion channels and non-specific homeostatic functions. When studying the role of ion channels in cancer cells, it is indispensable to choose experimental conditions that come close to the in vivo situation. Thus, environmental parameters, such as low oxygen pressure, acidosis and exposure to serum proteins, have to be taken into account. In order to achieve clinical application, more studies on the original cancer tissue are required, and improved animal models. Finally, it will be essential to generate more potent and specific inhibitors of ion channels to overcome the shortcomings of some of the current approaches.

  15. Creating Special Events

    ERIC Educational Resources Information Center

    deLisle, Lee

    2009-01-01

    "Creating Special Events" is organized as a systematic approach to festivals and events for students who seek a career in event management. This book looks at the evolution and history of festivals and events and proceeds to the nuts and bolts of event management. The book presents event management as the means of planning, organizing, directing,…

  16. [Voltage gated calcium channels: structure, characteristics and terminology].

    PubMed

    Veizerová, L; Svetlík, J; Kettmann, V

    2007-07-01

    Voltage-gated Ca2+ channels are the major pathway of Ca2+ entry into the cells. Their activity is essential to couple electrical signals from the cell surface to physiological events in cells. Several pharmacologically, structurally and kinetically distinct calcium channel types have been identified at the electrophysiological and molecular levels. This review aims to describe the functional, structural and pharmacological properties of voltage-gated calcium channels.

  17. Ion channels in plants

    PubMed Central

    Baluška, František; Mancuso, Stefano

    2013-01-01

    In his recent opus magnum review paper published in the October issue of Physiology Reviews, Rainer Hedrich summarized the field of plant ion channels.1 He started from the earliest electric recordings initiated by Charles Darwin of carnivorous Dionaea muscipula,1,2 known as Venus flytrap, and covered the topic extensively up to the most recent discoveries on Shaker-type potassium channels, anion channels of SLAC/SLAH families, and ligand-activated channels of glutamate receptor-like type (GLR) and cyclic nucleotide-gated channels (CNGC).1 PMID:23221742

  18. Cardiac ion channels

    PubMed Central

    Priest, Birgit T; McDermott, Jeff S

    2015-01-01

    Ion channels are critical for all aspects of cardiac function, including rhythmicity and contractility. Consequently, ion channels are key targets for therapeutics aimed at cardiac pathophysiologies such as atrial fibrillation or angina. At the same time, off-target interactions of drugs with cardiac ion channels can be the cause of unwanted side effects. This manuscript aims to review the physiology and pharmacology of key cardiac ion channels. The intent is to highlight recent developments for therapeutic development, as well as elucidate potential mechanisms for drug-induced cardiac side effects, rather than present an in-depth review of each channel subtype. PMID:26556552

  19. C. elegans TRP channels.

    PubMed

    Xiao, Rui; Xu, X Z Shawn

    2011-01-01

    Transient receptor potential (TRP) channels represent a superfamily of cation channels found in all eukaryotes. The C. elegans genome encodes seventeen TRP channels covering all of the seven TRP subfamilies. Genetic analyses in C. elegans have implicated TRP channels in a wide spectrum of behavioral and physiological processes, ranging from sensory transduction (e.g. chemosensation, touch sensation, proprioception and osmosensation) to fertilization, drug dependence, organelle biogenesis, apoptosis, gene expression, and neurotransmitter/hormone release. Many C. elegans TRP channels share similar activation and regulatory mechanisms with their vertebrate counterparts. Studies in C. elegans have also revealed some previously unrecognized functions and regulatory mechanisms of TRP channels. C. elegans represents an excellent genetic model organism for the study of function and regulation of TRP channels in vivo. PMID:21290304

  20. Mechanically Activated Ion Channels

    PubMed Central

    Ranade, Sanjeev S.; Syeda, Ruhma; Patapoutian, Ardem

    2015-01-01

    Mechanotransduction, the conversion of physical forces into biochemical signals, is an essential component of numerous physiological processes including not only conscious senses of touch and hearing, but also unconscious senses such as blood pressure regulation. Mechanically activated (MA) ion channels have been proposed as sensors of physical force, but the identity of these channels and an understanding of how mechanical force is transduced has remained elusive. A number of recent studies on previously known ion channels along with the identification of novel MA ion channels have greatly transformed our understanding of touch and hearing in both vertebrates and invertebrates. Here, we present an updated review of eukaryotic ion channel families that have been implicated in mechanotransduction processes and evaluate the qualifications of the candidate genes according to specified criteria. We then discuss the proposed gating models for MA ion channels and highlight recent structural studies of mechanosensitive potassium channels. PMID:26402601

  1. C. elegans TRP channels

    PubMed Central

    Xiao, Rui; Xu, X.Z. Shawn

    2010-01-01

    TRP (transient receptor potential) channels represent a superfamily of cation channels found in all eukaryotes. The C. elegans genome encodes seventeen TRP channels covering all of the seven TRP subfamilies. Genetic analyses in C. elegans have implicated TRP channels in a wide spectrum of behavioral and physiological processes, ranging from sensory transduction (e.g. chemosensation, touch sensation, proprioception and osmosensation) to fertilization, drug dependence, organelle biogenesis, apoptosis, gene expression, and neurotransmitter/hormone release. Many C. elegans TRP channels share similar activation and regulatory mechanisms with their vertebrate counterparts. Studies in C. elegans have also revealed some previously unrecognized functions and regulatory mechanisms of TRP channels. C. elegans represents an excellent genetic model organism for the study of function and regulation of TRP channels in vivo. PMID:21290304

  2. Flow of foam through a convergent channel.

    PubMed

    Dollet, Benjamin; Bocher, Claire

    2015-11-01

    We study experimentally the flow of a foam confined as a bubble monolayer between two plates through a convergent channel. We quantify the velocity, the distribution and orientation of plastic events, and the elastic stress, using image analysis. We use two different soap solutions: a sodium dodecyl sulfate (SDS) solution, with a negligible wall friction between the bubbles and the confining plates, and a mixture containing a fatty acid, giving a large wall friction. We show that for SDS solutions, the velocity profile obeys a self-similar form which results from the superposition of plastic events, and the elastic deformation is uniform. For the other solution, the velocity field differs and the elastic deformation increases towards the exit of the channel. We discuss and quantify the role of wall friction on the velocity profile, the elastic deformation, and the rate of plastic events. PMID:26607260

  3. Construction dynamics of a lava channel

    NASA Astrophysics Data System (ADS)

    Harris, Andrew J. L.; Favalli, Massimiliano; Mazzarini, Francesco; Hamilton, Christopher W.

    2009-05-01

    of this short-lived case show that care must be taken when using channel dimensions to infer flow dynamics. In our case, the full channel depth is not exposed. Instead the channel floor morphology reflects late stage pond filling and drainage rather than true channel-contained flow. Components of the compound levee relate to different flow regimes operating at different times during the eruption and associated with different effusion rates, flow dynamics and time scales. For example, although high effusion rate, brim-full flow was maintained for a small fraction of the channel lifetime, it emplaced a pile of pahoehoe overflow units that account for 60% of the total levee height. We show how time-varying volume flux is an important parameter in controlling channel construction dynamics. Because the complex history of lava delivery to a channel system is recorded by the final channel morphology, time-varying flow dynamics can be determined from the channel morphology. Developing methods for quantifying detailed flux histories for effusive events from the evidence in outcrop is therefore highly valuable. We here achieve this by using high-resolution spatial data for a channel system at Kilauea. This study not only indicates those physical and dynamic characteristics that are typical for basaltic lava flows on Hawaiian volcanoes, but also a methodology that can be widely applied to effusive basaltic eruptions.

  4. Fading channel simulator

    DOEpatents

    Argo, Paul E.; Fitzgerald, T. Joseph

    1993-01-01

    Fading channel effects on a transmitted communication signal are simulated with both frequency and time variations using a channel scattering function to affect the transmitted signal. A conventional channel scattering function is converted to a series of channel realizations by multiplying the square root of the channel scattering function by a complex number of which the real and imaginary parts are each independent variables. The two-dimensional inverse-FFT of this complex-valued channel realization yields a matrix of channel coefficients that provide a complete frequency-time description of the channel. The transmitted radio signal is segmented to provide a series of transmitted signal and each segment is subject to FFT to generate a series of signal coefficient matrices. The channel coefficient matrices and signal coefficient matrices are then multiplied and subjected to inverse-FFT to output a signal representing the received affected radio signal. A variety of channel scattering functions can be used to characterize the response of a transmitter-receiver system to such atmospheric effects.

  5. Assessing Special Events.

    ERIC Educational Resources Information Center

    Neff, Bonita Dostal

    Special events defined as being "newsworthy events" are becoming a way of American life. They are also a means for making a lot of money. Examples of special events that are cited most frequently are often the most minor of events; e.g., the open house, the new business opening day gala, or a celebration of some event in an organization. Little…

  6. Solar Eruptive Events

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2012-01-01

    It s long been known that the Sun plays host to the most energetic explosions in the solar system. But key insights into the forms that energy takes have only recently become available. Solar flares have been phenomena of both academic and practical interest since their discovery in 1859. From the academic point of view, they are the nearest events for studying the explosive release of energy in astrophysical magnetized plasmas. From the practical point of view, they disrupt communication channels on Earth, from telegraph communications in 1859 to radio and television signals today. Flares also wreak havoc on the electrical power grid, satellite operations, and GPS signals, and energetic charged particles and radiation are dangerous to passengers on high-altitude polar flights and to astronauts. Flares are not the only explosive phenomena on the Sun. More difficult to observe but equally energetic are the large coronal mass ejections (CMEs), the ejection of up to ten billion tons of magnetized plasma into the solar wind at speeds that can exceed 1000 km/s. CMEs are primarily observed from the side, with coronagraphs that block out the bright disk of the Sun and lower solar atmosphere so that light scattered from the ejected mass can be seen. Major geomagnetic storms are now known to arise from the interaction of CMEs with Earth's magnetosphere. Solar flares are observed without CMEs, and CMEs are observed without flares. The two phenomena often occur together, however, and almost always do in the case of large flares and fast CMEs. The term solar eruptive event refers to the combination of a flare and a CME. Solar eruptive events generate a lot of heat: They can heat plasma to temperatures as high at 50 million Kelvin, producing radiation across the electromagnetic spectrum. But that s not all. A fascinating aspect of solar eruptive events is the acceleration of electrons and ions to suprathermal often relativistic energies. The accelerated particles are primarily

  7. Morphodynamics of debris flow-dominated channels

    NASA Astrophysics Data System (ADS)

    Huebl, Johannes

    2013-04-01

    The mountain environment is mainly shaped by mass movements and glacial, debris flow and fluvial erosion. Therefore the landform ensemble of torrential catchments includes features of several thousand years. Many of them contribute as debris sources to the development of debris flow activity. But the torrential channel is not formed by different types of slope failures only, channel erosion itself plays a dominant role in the development of debris flows. Today LIDAR data allow us to identify different types of debris sources and subsequent channel features. In combination with the lithological setting this information helps us to understand the general morphodynamics of mountain channels. A deeper insight into the development of mountain channels lacks of consistent data sets. Different approaches try to estimate erosional rates of torrents during design events. These methods are mainly based on field survey and on the experience of the person doing this job. To decrease the uncertainty of these data, the collected data have to be checked against already existing data of documented former events. The development of the erosional processes in torrents is directly linked with the dominating morphodynamic process, leading to essential estimates of debris flow hydrographes.

  8. Event Segmentation Ability Uniquely Predicts Event Memory

    PubMed Central

    Sargent, Jesse Q.; Zacks, Jeffrey M.; Hambrick, David Z.; Zacks, Rose T.; Kurby, Christopher A.; Bailey, Heather R.; Eisenberg, Michelle L.; Beck, Taylor M.

    2013-01-01

    Memory for everyday events plays a central role in tasks of daily living, autobiographical memory, and planning. Event memory depends in part on segmenting ongoing activity into meaningful units. This study examined the relationship between event segmentation and memory in a lifespan sample to answer the following question: Is the ability to segment activity into meaningful events a unique predictor of subsequent memory, or is the relationship between event perception and memory accounted for by general cognitive abilities? Two hundred and eight adults ranging from 20 to 79 years old segmented movies of everyday events and attempted to remember the events afterwards. They also completed psychometric ability tests and tests measuring script knowledge for everyday events. Event segmentation and script knowledge both explained unique variance in event memory above and beyond the psychometric measures, and did so as strongly in older as in younger adults. These results suggest that event segmentation is a basic cognitive mechanism, important for memory across the lifespan. PMID:23942350

  9. Jamming in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; Steel, Fiona

    2011-03-01

    We study jamming of low aspect-ratio cylindrical Delrin grains in a vertical channel. Grain heights are less than their diameter so the grains resemble antacid tablets, coins, or poker chips. These grains are allowed to fall through a vertical channel with a square cross section where the channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. Grains are sometimes observed to form jams, stable structures supported by the channel walls with no support beneath them. The probability of jam occurrence and the strength or robustness of a jam is effected by grain and channel sizes. We will present experimental measurements of the jamming probability and jam strength in this system and discuss the relationship of these results to other experiments and theories. Supported by an Undergraduate Research Grant from Penn State Erie, The Behrend College.

  10. Mechanosensitive channels in microbes.

    PubMed

    Kung, Ching; Martinac, Boris; Sukharev, Sergei

    2010-01-01

    All cells, including microbes, detect and respond to mechanical forces, of which osmotic pressure is most ancient and universal. Channel proteins have evolved such that they can be directly stretched open when the membrane is under turgor pressure. Osmotic downshock, as in rain, opens bacterial mechanosensitive (MS) channels to jettison osmolytes, relieving pressure and preventing cell lysis. The ion flux through individual channel proteins can be observed directly with a patch clamp. MS channels of large and small conductance (MscL and MscS, respectively) have been cloned, crystallized, and subjected to biophysical and genetic analyses in depth. They are now models to scrutinize how membrane forces direct protein conformational changes. Eukaryotic microbes have homologs from animal sensory channels of the TRP superfamily. The MS channel in yeast is also directly sensitive to membrane stretch. This review examines the key concept that proteins embedded in the lipid bilayer can respond to the changes in the mechanical environment the lipid bilayer provides.

  11. Amyloid peptide channels.

    PubMed

    Kagan, B L; Azimov, R; Azimova, R

    2004-11-01

    At least 16 distinct clinical syndromes including Alzheimer's disease (AD), Parkinson's disease (PD), rheumatoid arthritis, type II diabetes mellitus (DM), and spongiform encephelopathies (prion diseases), are characterized by the deposition of amorphous, Congo red-staining deposits known as amyloid. These "misfolded" proteins adopt beta-sheet structures and aggregate spontaneously into similar extended fibrils despite their widely divergent primary sequences. Many, if not all, of these peptides are capable of forming ion-permeable channels in vitro and possibly in vivo. Common channel properties include irreversible, spontaneous insertion into membranes, relatively large, heterogeneous single-channel conductances, inhibition of channel formation by Congo red, and blockade of inserted channels by Zn2+. Physiologic effects of amyloid, including Ca2+ dysregulation, membrane depolarization, mitochondrial dysfunction, inhibition of long-term potentiation (LTP), and cytotoxicity, suggest that channel formation in plasma and intracellular membranes may play a key role in the pathophysiology of the amyloidoses. PMID:15702375

  12. HIPPI and Fibre Channel

    SciTech Connect

    Tolmie, D.E.

    1992-01-01

    The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background.

  13. Event-Based Science.

    ERIC Educational Resources Information Center

    Wright, Russell G.

    1992-01-01

    Suggests that an event-based science curriculum can provide the framework for deciding what to retain in an overloaded science curriculum. Provides examples of current events and the science concepts explored related to the event. (MDH)

  14. Symmetrization for redundant channels

    NASA Technical Reports Server (NTRS)

    Tulplue, Bhalchandra R. (Inventor); Collins, Robert E. (Inventor)

    1988-01-01

    A plurality of redundant channels in a system each contain a global image of all the configuration data bases in each of the channels in the system. Each global image is updated periodically from each of the other channels via cross channel data links. The global images of the local configuration data bases in each channel are separately symmetrized using a voting process to generate a system signal configuration data base which is not written into by any other routine and is available for indicating the status of the system within each channel. Equalization may be imposed on a suspect signal and a number of chances for that signal to heal itself are provided before excluding it from future votes. Reconfiguration is accomplished upon detecting a channel which is deemed invalid. A reset function is provided which permits an externally generated reset signal to permit a previously excluded channel to be reincluded within the system. The updating of global images and/or the symmetrization process may be accomplished at substantially the same time within a synchronized time frame common to all channels.

  15. Phosphoinositides regulate ion channels

    PubMed Central

    Hille, Bertil; Dickson, Eamonn J.; Kruse, Martin; Vivas, Oscar; Suh, Byung-Chang

    2014-01-01

    Phosphoinositides serve as signature motifs for different cellular membranes and often are required for the function of membrane proteins. Here, we summarize clear evidence supporting the concept that many ion channels are regulated by membrane phosphoinositides. We describe tools used to test their dependence on phosphoinositides, especially phosphatidylinositol 4,5-bisphosphate, and consider mechanisms and biological meanings of phosphoinositide regulation of ion channels. This lipid regulation can underlie changes of channel activity and electrical excitability in response to receptors. Since different intracellular membranes have different lipid compositions, the activity of ion channels still in transit towards their final destination membrane may be suppressed until they reach an optimal lipid environment. PMID:25241941

  16. IBEX channel formation

    SciTech Connect

    Jones, E.E.; Frost, C.A.; Freeman, J.R.; Jojola, J.M.

    1987-01-01

    Exploding wire experiments have been conducted to form a low-density channel for endoatmospheric channel-tracking experiments to be performed on the IBEX accelerator. Stainless steel and tungsten wires as small as six microns radius have been exploded using a 50 kJ, 200 kV fast capacitor bank designed and constructed for the purpose. Density channels have been produced. Preliminary results will be compared with a simple circuit model and hydrocode analysis. Efforts to diagnose the low-density channel are beginning. 5 refs.

  17. Conductance of Ion Channels - Theory vs. Experiment

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Wilson, Michael; Mijajlovic, Milan

    2013-01-01

    Transmembrane ion channels mediate a number of essential physiological processes in a cell ranging from regulating osmotic pressure to transmission of neural signals. Kinetics and selectivity of ion transport is of critical importance to a cell and, not surprisingly, it is a subject of numerous experimental and theoretical studies. In this presentation we will analyze in detail computer simulations of two simple channels from fungi - antiamoebin and trichotoxin. Each of these channels is made of an alpha-helical bundle of small, nongenomically synthesized peptides containing a number of rare amino acids and exhibits strong antimicrobial activity. We will focus on calculating ionic conductance defined as the ratio of ionic current through the channel to applied voltage. From molecular dynamics simulations, conductance can be calculated in at least two ways, each involving different approximations. Specifically, the current, given as the number of charges transferred through the channel per unit of time, can be obtained from the number of events in which ions cross the channel during the simulation. This method works well for large currents (high conductance values and/or applied voltages). If the number of crossing events is small, reliable estimates of current are difficult to achieve. Alternatively, conductance can be estimated assuming that ion transport can be well approximated as diffusion in the external potential given by the free energy profile. Then, the current can be calculated by solving the one-dimensional diffusion equation in this external potential and applied voltage (the generalized Nernst-Planck equation). To do so three ingredients are needed: the free energy profile, the position-dependent diffusion coefficient and the diffusive flux of ions into the channel. All these quantities can be obtained from molecular dynamics simulations. An important advantage of this method is that it can be used equally well to estimating large and small currents

  18. A linearization of quantum channels

    NASA Astrophysics Data System (ADS)

    Crowder, Tanner

    2015-06-01

    Because the quantum channels form a compact, convex set, we can express any quantum channel as a convex combination of extremal channels. We give a Euclidean representation for the channels whose inverses are also valid channels; these are a subset of the extreme points. They form a compact, connected Lie group, and we calculate its Lie algebra. Lastly, we calculate a maximal torus for the group and provide a constructive approach to decomposing any invertible channel into a product of elementary channels.

  19. Basaltic Lava Channels

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.; Griffiths, R. W.; Kerr, R. C.

    2004-12-01

    In Hawaii, the mode of lava transport - through open channels or through insulating lava tubes - determines the thermal, rheological, and emplacement history of a lava flow. Most Hawaiian lavas are erupted at near-liquidus temperatures and are therefore crystal-poor; lava transport through open channels allows rapid cooling and consequent rapid increases in lava crystallinity. Solidified aa flows resulting from channelized flow are typically fine-grained throughout their thickness, indicating cooling of the entire flow thickness during transport. In contrast, transport of lava through insulating tubes permits flow over long distances with little cooling. Flows emerging from such tubes typically have pahoehoe flow surfaces with glassy crusts. Groundmass textures that coarsen from the flow rind to the interior reflect rates of post-emplacement, rather than syn-emplacement, cooling. To distinguish eruption conditions that result in lava channels from those that allow formation of lava tubes, we have performed a series of laboratory experiments involving injection of PEG 600 (a wax with a Newtonian rheology and freezing temperature of 19ºC) into cold water through both uniform and non-uniform sloping channels. In uniform channels, tube formation can be distinguished from open channel flow using a dimensionless parameter based on a solidification time scale, an advection time scale, and a Rayleigh number that describes convection by heat loss from crust-free shear zones. Theoretical analysis predicts that in the open channel regime, the width of the crust (dc) will vary with the channel width (W) as dc = W5/3. Crustal coverage of non-uniform channels in both laboratory experiments and field examples from Kilauea Volcano, Hawaii, is consistent with this prediction. However, experiments in non-uniform channels illustrate additional controls on the surface coverage of lava channels. Most important is crustal extension resulting from flow acceleration through constrictions

  20. Ion channels in microbes

    PubMed Central

    Martinac, Boris; Saimi, Yoshiro; Kung, Ching

    2008-01-01

    Summary Studies of ion channels have for long been dominated by the animalcentric, if not anthropocentric view of physiology. The structures and activities of ion channels had, however, evolved long before the appearance of complex multicellular organisms on Earth. The diversity of ion channels existing in cellular membranes of prokaryotes is a good example. Though at first it may appear as a paradox that most of what we know about the structure of eukaryotic ion channels is based on the structure of bacterial channels, this should not be surprising given the evolutionary relatedness of all living organisms and suitability of microbial cells for structural studies of biological macromolecules in a laboratory environment. Genome sequences of the human as well as various microbial, plant and animal organisms unambiguously established the evolutionary links, whereas crystallographic studies of the structures of major types of ion channels published over the last decade clearly demonstrated the advantage of using microbes as experimental organisms. The purpose of this review is not only to provide an account of acquired knowledge on microbial ion channels but also to show that the study of microbes and their ion channels may also hold a key to solving unresolved molecular mysteries in the future. PMID:18923187

  1. Generalized channeled polarimetry.

    PubMed

    Alenin, Andrey S; Tyo, J Scott

    2014-05-01

    Channeled polarimeters measure polarization by modulating the measured intensity in order to create polarization-dependent channels that can be demodulated to reveal the desired polarization information. A number of channeled systems have been described in the past, but their proposed designs often unintentionally sacrifice optimality for ease of algebraic reconstruction. To obtain more optimal systems, a generalized treatment of channeled polarimeters is required. This paper describes methods that enable handling of multi-domain modulations and reconstruction of polarization information using linear algebra. We make practical choices regarding use of either Fourier or direct channels to make these methods more immediately useful. Employing the introduced concepts to optimize existing systems often results in superficial system changes, like changing the order, orientation, thickness, or spacing of polarization elements. For the two examples we consider, we were able to reduce noise in the reconstruction to 34.1% and 57.9% of the original design values. PMID:24979633

  2. Athermalized channeled spectropolarimeter enhancement.

    SciTech Connect

    Jones, Julia Craven; Way, Brandyn Michael; Mercier, Jeffrey Alan; Hunt, Jeffery P.

    2013-09-01

    Channeled spectropolarimetry can measure the complete polarization state of light as a function of wavelength. Typically, a channeled spectropolarimeter uses high order retarders made of uniaxial crystal to amplitude modulate the measured spectrum with the spectrally-dependent Stokes polarization information. A primary limitation of conventional channeled spectropolarimeters is related to the thermal variability of the retarders. Thermal variation often forces frequent system recalibration, particularly for field deployed systems. However, implementing thermally stable retarders, made of biaxial crystal, results in an athermal channeled spectropolarimeter that relieves the need for frequent recalibration. This report presents experimental results for an anthermalized channeled spectropolarimeter prototype produced using potassium titanyl phosphate. The results of this prototype are compared to the current thermal stabilization state of the art. Finally, the application of the technique to the thermal infrared is studied, and the athermalization concept is applied to an infrared imaging spectropolarimeter design.

  3. Jamming in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; McCausland, Jeffrey; Steel, Fiona

    2010-03-01

    We experimentally study jamming of cylindrical grains in a vertical channel. The grains have a low aspect-ratio (height/diameter < 1) so their shape is like antacid tablets or poker chips. They are allowed to fall through a vertical channel with a square cross section. The channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. It is observed that grains sometimes jam in this apparatus. In a jam, grains form a stable structure from one side of the channel to the other with nothing beneath them. Jams may be strong enough to support additional grains above. The probability of a jam occurring is a function of the grain height and diameter. We will present experimental measurements of the jamming probability in this system and discuss the relationship of these results to other experiments and theories.

  4. Event-by-Event Simulation of Induced Fission

    SciTech Connect

    Vogt, Ramona; Randrup, Joergen

    2008-04-17

    We are developing a novel code that treats induced fission by statistical (or Monte-Carlo) simulation of individual decay chains. After its initial excitation, the fissionable compound nucleus may either de-excite by evaporation or undergo binary fission into a large number of fission channels each with different energetics involving both energy dissipation and deformed scission pre-fragments. After separation and Coulomb acceleration, each fission fragment undergoes a succession of individual (neutron) evaporations, leading to two bound but still excited fission products (that may further decay electromagnetically and, ultimately, weakly), as well as typically several neutrons. (The inclusion of other possible ejectiles is planned.) This kind of approach makes it possible to study more detailed observables than could be addressed with previous treatments which have tended to focus on average quantities. In particular, any type of correlation observable can readily be extracted from a generated set of events. With a view towards making the code practically useful in a variety of applications, emphasis is being put on making it numerically efficient so that large event samples can be generated quickly. In its present form, the code can generate one million full events in about 12 seconds on a MacBook laptop computer. The development of this qualitatively new tool is still at an early stage and quantitative reproduction of existing data should not be expected until a number of detailed refinement have been implemented.

  5. Event-by-Event Simulation of Induced Fission

    SciTech Connect

    Vogt, R; Randrup, J

    2007-12-13

    We are developing a novel code that treats induced fission by statistical (or Monte-Carlo) simulation of individual decay chains. After its initial excitation, the fissionable compound nucleus may either deexcite by evaporation or undergo binary fission into a large number of fission channels each with different energetics involving both energy dissipation and deformed scission prefragments. After separation and Coulomb acceleration, each fission fragment undergoes a succession of individual (neutron) evaporations, leading to two bound but still excited fission products (that may further decay electromagnetically and, ultimately, weakly), as well as typically several neutrons. (The inclusion of other possible ejectiles is planned.) This kind of approach makes it possible to study more detailed observables than could be addressed with previous treatments which have tended to focus on average quantities. In particular, any type of correlation observable can readily be extracted from a generated set of events. With a view towards making the code practically useful in a variety of applications, emphasis is being put on making it numerically efficient so that large event samples can be generated quickly. In its present form, the code can generate one million full events in about 12 seconds on a MacBook laptop computer. The development of this qualitatively new tool is still at an early stage and quantitative reproduction of existing data should not be expected until a number of detailed refinement have been implemented.

  6. Rain and channel flow supplements to subsurface water beneath hyper-arid ephemeral stream channels

    NASA Astrophysics Data System (ADS)

    Kampf, Stephanie K.; Faulconer, Joshua; Shaw, Jeremy R.; Sutfin, Nicholas A.; Cooper, David J.

    2016-05-01

    In hyper-arid regions, ephemeral stream channels are important sources of subsurface recharge and water supply for riparian vegetation, but few studies have documented the subsurface water content dynamics of these systems. This study examines ephemeral channels in the hyper-arid western Sonoran Desert, USA to determine how frequently water recharges the alluvial fill and identify variables that affect the depth and persistence of recharge. Precipitation, stream stage, and subsurface water content measurements were collected over a three-year study at six channels with varying contributing areas and thicknesses of alluvial fill. All channels contain coarse alluvium composed primarily of sands and gravels, and some locations also have localized layers of fine sediment at 2-3 m depth. Rain alone contributed 300-400 mm of water input to these channels over three years, but water content responses were only detected for 36% of the rain events at 10 cm depth, indicating that much of the rain water was either quickly evaporated or taken up by plants. Pulses of water from rain events were detected only in the top meter of alluvium. The sites each experienced ⩽5 brief flow events, which caused transient saturation that usually lasted only a few hours longer than flow. These events were the only apparent source of water to depths >1 m, and water from flow events quickly percolated past the deepest measurement depths (0.5-3 m). Sustained saturation in the shallow subsurface only developed where there was a near-surface layer of finer consolidated sediments that impeded deep percolation.

  7. Channel Narrowing and Channel Reset: Effects of a Large Flood on the Vegetated, Narrowing Rio Grande

    NASA Astrophysics Data System (ADS)

    Dean, D. J.; Schmidt, J. C.

    2009-12-01

    In September 2008, heavy precipitation from a tropical storm in the Sierra Madre Occidental, MX, produced large amounts of stream flow to the Rio Conchos and lower Rio Grande. This flood was well publicized in the media due to the widespread flooding in Ojinaga, Chih., and Presidio, TX. Gage records indicate that this flood had an approximate recurrence of 15 years as measured on the Rio Grande near Presidio. Nevertheless, flood stages were the highest ever recorded and resulted from a significant loss of channel capacity due to channel narrowing that had occurred during the previous 18 years. Measurements from aerial photographs indicate that channel width had decreased between 35 and 50% between 1990 and 2008 during regional drought. During this period of low stream flow, invasion by non-native riparian vegetation (Tamarix spp., Arundo donax) helped trap sediment and promote floodplain accretion. Our resurveys of the channel indicate that the 2008 flood was a reset event and that the channel was re-widened by 32 to 48%. Repeated, oblique photographs showed significant channel migration and large scale floodplain stripping during this flood. These results show that although riparian vegetation may actively promote channel narrowing and floodplain accretion, moderately large floods may cause large scale bank erosion, floodplain stripping, and vegetation removal in alluvial valleys subject to large-scale invasion by nonnative plants.

  8. Fine Channel Networks

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A color image of fine channel networks on Mars; north toward top. The scene shows heavily cratered highlands dissected by dendritic open channel networks that dissect steep slopes of impact crater walls. This image is a composite of Viking high-resolution images in black and white and low-resolution images in color. The image extends from latitude 9 degrees S. to 5 degrees S. and from longitude 312 degrees to 320 degrees; Mercator projection. The dendritic pattern of the fine channels and their location on steep slopes leads to the interpretation that these are runoff channels. The restriction of these types of channels to ancient highland rocks suggests that these channels are old and date from a time on Mars when conditions existed for precipitation to actively erode rocks. After the channels reach a low plain, they appear to end. Termination may have resulted from burial by younger deposits or perhaps the flows percolated into the surface materials and continued underground.

  9. Why are Channels Sinuous?

    NASA Astrophysics Data System (ADS)

    Constantine, J. A.; Lazarus, E.

    2012-12-01

    Sinuosity is a ubiquitous property of channelized flow patterns on Earth and other planetary bodies. Sinuosity is typically discussed as an emergent consequence of migration processes in meandering rivers, but meandering rivers are only one type of sinuous channel: there are many examples that show little or no indication of meandering, such as bedrock river canyons, drainage channels in tidal mudflats, and volcanic rilles. In some of these patterns, sinuosity is described as "inherited" from a preexisting morphology, which elides an explanation for how the inherited sinuosity originated. Even in river meandering theory there is ongoing debate regarding how initial channel sinuosity arises. Comparing the results of a generalized flow-routing model to observations of natural flow patterns, we find that the ratio of floodplain resistance (R, representing topographic roughness, substrate erodibility, or vegetation density) relative to floodplain slope (m) produces a range of sinuous planforms with natural analogs. We offer a unifying theory for channel sinuosity in which this ratio of resistance to slope (R:m) exerts the primary landscape control on planform shape and predicts the range of sinuosity a floodplain may express. Resistance-dominated floodplains produce channels with higher sinuosity than those of slope-dominated floodplains because increased resistance impedes down-slope flow. Measurement of "relative resistance" (R:m) could inform how riparian restoration projects evaluate the floodplains of artificially straightened rivers. Our analysis suggests that if the sinuosity of a formerly natural channel derived from a high R:m, then even a channel redesigned to be sinuous will straighten if the relative resistance of its floodplain is suppressed or inherently low. (Alternatively, increasing floodplain resistance might foster a higher sinuosity than hydraulic geometry would forecast.) The explanation for sinuosity that we propose is universal enough to account

  10. Fractional channel multichannel analyzer

    DOEpatents

    Brackenbush, Larry W.; Anderson, Gordon A.

    1994-01-01

    A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynscronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board.

  11. Channel Access in Erlang

    SciTech Connect

    Nicklaus, Dennis J.

    2013-10-13

    We have developed an Erlang language implementation of the Channel Access protocol. Included are low-level functions for encoding and decoding Channel Access protocol network packets as well as higher level functions for monitoring or setting EPICS process variables. This provides access to EPICS process variables for the Fermilab Acnet control system via our Erlang-based front-end architecture without having to interface to C/C++ programs and libraries. Erlang is a functional programming language originally developed for real-time telecommunications applications. Its network programming features and list management functions make it particularly well-suited for the task of managing multiple Channel Access circuits and PV monitors.

  12. Episodes, events, and models

    PubMed Central

    Khemlani, Sangeet S.; Harrison, Anthony M.; Trafton, J. Gregory

    2015-01-01

    We describe a novel computational theory of how individuals segment perceptual information into representations of events. The theory is inspired by recent findings in the cognitive science and cognitive neuroscience of event segmentation. In line with recent theories, it holds that online event segmentation is automatic, and that event segmentation yields mental simulations of events. But it posits two novel principles as well: first, discrete episodic markers track perceptual and conceptual changes, and can be retrieved to construct event models. Second, the process of retrieving and reconstructing those episodic markers is constrained and prioritized. We describe a computational implementation of the theory, as well as a robotic extension of the theory that demonstrates the processes of online event segmentation and event model construction. The theory is the first unified computational account of event segmentation and temporal inference. We conclude by demonstrating now neuroimaging data can constrain and inspire the construction of process-level theories of human reasoning. PMID:26578934

  13. Ion Channels as Drug Targets in Central Nervous System Disorders

    PubMed Central

    Waszkielewicz, A.M; Gunia, A; Szkaradek, N; Słoczyńska, K; Krupińska, S; Marona, H

    2013-01-01

    Ion channel targeted drugs have always been related with either the central nervous system (CNS), the peripheral nervous system, or the cardiovascular system. Within the CNS, basic indications of drugs are: sleep disorders, anxiety, epilepsy, pain, etc. However, traditional channel blockers have multiple adverse events, mainly due to low specificity of mechanism of action. Lately, novel ion channel subtypes have been discovered, which gives premises to drug discovery process led towards specific channel subtypes. An example is Na+ channels, whose subtypes 1.3 and 1.7-1.9 are responsible for pain, and 1.1 and 1.2 – for epilepsy. Moreover, new drug candidates have been recognized. This review is focusing on ion channels subtypes, which play a significant role in current drug discovery and development process. The knowledge on channel subtypes has developed rapidly, giving new nomenclatures of ion channels. For example, Ca2+ channels are not any more divided to T, L, N, P/Q, and R, but they are described as Cav1.1-Cav3.3, with even newer nomenclature α1A-α1I and α1S. Moreover, new channels such as P2X1-P2X7, as well as TRPA1-TRPV1 have been discovered, giving premises for new types of analgesic drugs. PMID:23409712

  14. The global event system

    SciTech Connect

    Winans, J.

    1994-03-02

    The support for the global event system has been designed to allow an application developer to control the APS event generator and receiver boards. This is done by the use of four new record types. These records are customized and are only supported by the device support modules for the APS event generator and receiver boards. The use of the global event system and its associated records should not be confused with the vanilla EPICS events and the associated event records. They are very different.

  15. Channel in Kasei

    NASA Technical Reports Server (NTRS)

    2004-01-01

    14 November 2004 The Kasei Valles are a suite of very large, ancient outflow channels. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the youngest channel system in the Kasei Valles. Torrents of mud, rocks, and water carved this channel as flow was constricted through a narrow portion of the valley. Layers exposed by the erosion that created the channel can be seen in its walls. This 1.4 meters (5 feet) per pixel image is located near 21.1oN, 72.6oW. The picture covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

  16. Chondrocyte channel transcriptomics

    PubMed Central

    Lewis, Rebecca; May, Hannah; Mobasheri, Ali; Barrett-Jolley, Richard

    2013-01-01

    To date, a range of ion channels have been identified in chondrocytes using a number of different techniques, predominantly electrophysiological and/or biomolecular; each of these has its advantages and disadvantages. Here we aim to compare and contrast the data available from biophysical and microarray experiments. This letter analyses recent transcriptomics datasets from chondrocytes, accessible from the European Bioinformatics Institute (EBI). We discuss whether such bioinformatic analysis of microarray datasets can potentially accelerate identification and discovery of ion channels in chondrocytes. The ion channels which appear most frequently across these microarray datasets are discussed, along with their possible functions. We discuss whether functional or protein data exist which support the microarray data. A microarray experiment comparing gene expression in osteoarthritis and healthy cartilage is also discussed and we verify the differential expression of 2 of these genes, namely the genes encoding large calcium-activated potassium (BK) and aquaporin channels. PMID:23995703

  17. Proton channel models

    PubMed Central

    Pupo, Amaury; Baez-Nieto, David; Martínez, Agustín; Latorre, Ramón; González, Carlos

    2014-01-01

    Voltage-gated proton channels are integral membrane proteins with the capacity to permeate elementary particles in a voltage and pH dependent manner. These proteins have been found in several species and are involved in various physiological processes. Although their primary topology is known, lack of details regarding their structures in the open conformation has limited analyses toward a deeper understanding of the molecular determinants of their function and regulation. Consequently, the function-structure relationships have been inferred based on homology models. In the present work, we review the existing proton channel models, their assumptions, predictions and the experimental facts that support them. Modeling proton channels is not a trivial task due to the lack of a close homolog template. Hence, there are important differences between published models. This work attempts to critically review existing proton channel models toward the aim of contributing to a better understanding of the structural features of these proteins. PMID:24755912

  18. Calcium channel blocker overdose

    MedlinePlus

    ... Goldschlager N. Cardiovascular toxicology. In: Shannon MW, Borron SW, Burns MJ, eds. Haddad and Winchester's Clinical Management ... SD. Calcium channel antagonists. In: Shannon MW, Borron SW, Burns MJ, eds. Haddad and Winchester's Clinical Management ...

  19. TRP channels in disease.

    PubMed

    Jordt, S E; Ehrlich, B E

    2007-01-01

    The transient receptor potential (TRP) channels are a large family of proteins with six main subfamilies termed the TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), and TRPA (ankyrin) groups. The sheer number of different TRPs with distinct functions supports the statement that these channels are involved in a wide range of processes ranging from sensing of thermal and chemical signals to reloading intracellular stores after responding to an extracellular stimulus. Mutations in TRPs are linked to pathophysiology and specific diseases. An understanding of the role of TRPs in normal physiology is just beginning; the progression from mutations in TRPs to pathophysiology and disease will follow. In this review, we focus on two distinct aspects of TRP channel physiology, the role of TRP channels in intracellular Ca2+ homeostasis, and their role in the transduction of painful stimuli in sensory neurons. PMID:18193640

  20. A Simple Water Channel

    ERIC Educational Resources Information Center

    White, A. S.

    1976-01-01

    Describes a simple water channel, for use with an overhead projector. It is run from a water tap and may be used for flow visualization experiments, including the effect of streamlining and elementary building aerodynamics. (MLH)

  1. Late Holocene channel changes of the Middle Trent: channel response to a thousand-year flood record

    NASA Astrophysics Data System (ADS)

    Brown, A. G.; Cooper, L.; Salisbury, C. R.; Smith, D. N.

    2001-07-01

    This paper presents recent work on the floodplain sedimentology of the Middle Trent using data from gravel pits, archaeological sites and documentary sources. The Middle Trent has been unusually active during the Holocene in comparison with other large lowland rivers in the British Isles. The Holocene floodplain fill is dominated by sands and gravels with abundant structural evidence of changes in channel pattern and channel type. A thousand-year record of channel change has been reconstructed from palaeochannels and gravel units with radiocarbon dating of brushwood, palaeomagnetic dating of fine channel fills, dendrochronological dating of timber structures and dating via archaeological typologies. The Trent also has a reasonably well-recorded flood history at least since the 11th century AD. A comparison of the flood record and channel change indicates that the same degree of morphological and sedimentary response is not necessarily associated with floods of similar magnitudes, i.e. there is no constant relationship between event magnitude and landform change. Instead, the response seems dependent on the existing state of the channel and medium-term trajectory of channel change. There is evidence at both the Hemington and Colwick reaches of a cycle of channel change involving a change in channel typology, and dating evidence that this may have migrated downstream. The results of this work provide a medium-term perspective on channel change, which may be more appropriate for large British rivers than short-term monitoring for both model validation and planning purposes.

  2. Combined single channel and single molecule detection identifies subunit composition of STIM1-activated transient receptor potential canonical (TRPC) channels.

    PubMed

    Asanov, Alexander; Sampieri, Alicia; Moreno, Claudia; Pacheco, Jonathan; Salgado, Alfonso; Sherry, Ryan; Vaca, Luis

    2015-01-01

    Depletion of intracellular calcium ion stores initiates a rapid cascade of events culminating with the activation of the so-called Store-Operated Channels (SOC) at the plasma membrane. Calcium influx via SOC is essential in the initiation of calcium-dependent intracellular signaling and for the refilling of internal calcium stores, ensuring the regeneration of the signaling cascade. In spite of the significance of this evolutionary conserved mechanism, the molecular identity of SOC has been the center of a heated controversy spanning over the last 20 years. Initial studies positioned some members of the transient receptor potential canonical (TRPC) channel superfamily of channels (with the more robust evidence pointing to TRPC1) as a putative SOC. Recent evidence indicates that Stromal Interacting Molecule 1 (STIM1) activates some members from the TRPC family of channels. However, the exact subunit composition of TRPC channels remains undetermined to this date. To identify the subunit composition of STIM1-activated TRPC channels, we developed novel method, which combines single channel electrophysiological measurements based on the patch clamp technique with single molecule fluorescence imaging. We termed this method Single ion Channel Single Molecule Detection technique (SC-SMD). Using SC-SMD method, we have obtained direct evidence of the subunit composition of TRPC channels activated by STIM1. Furthermore, our electrophysiological-imaging SC-SMD method provides evidence at the molecular level of the mechanism by which STIM1 and calmodulin antagonize to modulate TRPC channel activity.

  3. Ion Channels in Epithelial Cells

    NASA Astrophysics Data System (ADS)

    Palmer, Lawrence G.

    Ion channels in epithelial cells serve to move ions, and in some cases fluid, between compartments of the body. This function of the transfer of material is fundamentally different from that of the transfer of information, which is the main job of most channels in excitable cells. Nevertheless the basic construction of the channels is similar in many respects in the two tissue types. This chapter reviews the nature of channels in epithelia and discusses how their functions have evolved to accomplish the basic tasks for which they are responsible. I will focus on three channel types: epithelial Na+ channels, inward-rectifier K+ channels, and CFTR Cl- channels.

  4. Channel-tunnels.

    PubMed

    Koronakis, V; Andersen, C; Hughes, C

    2001-08-01

    TolC and its many homologues comprise an alpha-helical transperiplasmic tunnel embedded in the bacterial outer membrane by a contiguous beta-barrel channel, providing a large exit duct for diverse substrates. The 'channel-tunnel' is closed at its periplasmic entrance, but can be opened by an 'iris-like' mechanism when recruited by substrate-engaged proteins in the cytosolic membrane.

  5. Vaccine Adverse Events

    MedlinePlus

    ... Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Vaccines, Blood & Biologics Home Vaccines, Blood & Biologics Safety & Availability ( ... Center for Biologics Evaluation & Research Vaccine Adverse Events Vaccine Adverse Events Share Tweet Linkedin Pin it More ...

  6. Morphodynamics of Floodplain Chute Channels

    NASA Astrophysics Data System (ADS)

    David, S. R.; Edmonds, D. A.

    2015-12-01

    Floodplain chute channel formation is a key process that can enable rivers to transition from single-thread to multi-thread planform geometries. Floodplain chute channels are usually incisional channels connecting topographic lows across point bars and in the floodplain. Surprisingly, it is still not clear what conditions promote chute channel formation and what governs their morphodynamic behavior. Towards this end we have initiated an empirical and theoretical study of floodplain chute channels in Indiana, USA. Using elevation models and satellite imagery we mapped 3064 km2 of floodplain in Indiana, and find that 37.3% of mapped floodplains in Indiana have extensive chute channel networks. These chute channel networks consist of two types of channel segments: meander cutoffs of the main channel and chute channels linking the cutoffs together. To understand how these chute channels link meander cutoffs together and eventually create floodplain channel networks we use Delft3D to explore floodplain morphodynamics. Our first modeling experiment starts from a generic floodplain prepopulated with meander cutoffs to test under what conditions chute channels form.We find that chute channel formation is optimized at an intermediate flood discharge. If the flood discharge is too large the meander cutoffs erosively diffuse, whereas if the floodwave is too small the cutoffs fill with sediment. A moderately sized floodwave reworks the sediment surrounding the topographic lows, enhancing the development of floodplain chute channels. Our second modeling experiments explore how floodplain chute channels evolve on the West Fork of the White River, Indiana, USA. We find that the floodplain chute channels are capable of conveying the entire 10 yr floodwave (Q=1330m3/s) leaving the inter-channel areas dry. Moreover, the chute channels can incise into the floodplain while the margins of channels are aggrading, creating levees. Our results suggest that under the right conditions

  7. Optical Communications Channel Combiner

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Quirk, Kevin J.; Nguyen, Danh H.; Nguyen, Huy

    2012-01-01

    NASA has identified deep-space optical communications links as an integral part of a unified space communication network in order to provide data rates in excess of 100 Mb/s. The distances and limited power inherent in a deep-space optical downlink necessitate the use of photon-counting detectors and a power-efficient modulation such as pulse position modulation (PPM). For the output of each photodetector, whether from a separate telescope or a portion of the detection area, a communication receiver estimates a log-likelihood ratio for each PPM slot. To realize the full effective aperture of these receivers, their outputs must be combined prior to information decoding. A channel combiner was developed to synchronize the log-likelihood ratio (LLR) sequences of multiple receivers, and then combines these into a single LLR sequence for information decoding. The channel combiner synchronizes the LLR sequences of up to three receivers and then combines these into a single LLR sequence for output. The channel combiner has three channel inputs, each of which takes as input a sequence of four-bit LLRs for each PPM slot in a codeword via a XAUI 10 Gb/s quad optical fiber interface. The cross-correlation between the channels LLR time series are calculated and used to synchronize the sequences prior to combining. The output of the channel combiner is a sequence of four-bit LLRs for each PPM slot in a codeword via a XAUI 10 Gb/s quad optical fiber interface. The unit is controlled through a 1 Gb/s Ethernet UDP/IP interface. A deep-space optical communication link has not yet been demonstrated. This ground-station channel combiner was developed to demonstrate this capability and is unique in its ability to process such a signal.

  8. Comparison of the 26 May 2012 SEP Event with the 3 November 2011 SEP Event

    NASA Astrophysics Data System (ADS)

    Makela, P. A.; Gopalswamy, N.; Thakur, N.; Xie, H.

    2015-12-01

    We compare the solar and interplanetary events associated with two large solar energetic particle (SEP) events on 26 May 2012 and 3 November 2011. Both SEP events were detected at three longitudinally widely separated locations by STEREO A and B spacecraft (more than 100 deg away from Earth) and the Wind and SOHO spacecraft near Earth. In Earth view, the November 2011 eruption occurred far behind the east limb at N09E154, whereas the May 2012 eruption occurred closer to the west limb at N15W121, suggesting that SEPs accelerated during the 2012 event might have easier access to Earth. Even though the 2012 event was more intense in the GOES >10 MeV proton channel (peak intensity 14 pfu) than the 2011 event (peak intensity 4 pfu), we find that the latter event was more intense at higher energies (> 40 MeV). Also, the initial rise at lower energies was slightly faster for the 2011 event as measured by SOHO/ERNE. In addition, the CME associated with the May 2012 event was faster with an estimated space speed of ~2029 km/s than that in the November 2011 event (1188 km/s). STEREO/EUVI images of the associated post-eruption arcades (PEAs) indicate that their orientations were different: the PEA of the May 2012 event had a high inclination (north-south), while the inclination of the PEA of the 2011 event was more moderate. Differences in the flux rope orientation may also have effect on the longitudinal extent of the SEP events. These observations suggest that the dependence of solar proton intensities on the observer's longitudinal distance from the solar source is more complex than traditionally assumed.

  9. Organellar Channels and Transporters

    PubMed Central

    Xu, Haoxing; Martinoia, Enrico; Szabo, Ildiko

    2015-01-01

    Decades of intensive research has led to the discovery of most plasma membrane ion channels and transporters and the characterization of their physiological functions. In contrast, although over 80% of transport processes occur inside the cells, the ion flux mechanisms across intracellular membranes (the endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes, mitochondria, chloroplasts, and vacuoles) are difficult to investigate and remain poorly understood. Recent technical advances in super-resolution microscopy, organellar electrophysiology, organelle-targeted fluorescence imaging, and organelle proteomics have pushed a large step forward in the research of intracellular ion transport. Many new organellar channels are molecularly identified and electrophysiologically characterized. Additionally, molecular identification of many of these ion channels/transporters has made it possible to study their physiological functions by genetic and pharmacological means. For example, organellar channels have been shown to regulate important cellular processes such as programmed cell death and photosynthesis, and are involved in many different pathologies. This Special Issue (SI) on Organellar Channels and Transporters aims to provide a forum to discuss the recent advances and to define the standard and open questions in this exciting and rapidly-developing field. Along this line, a new Gordon Research Conference dedicated to the multidisciplinary study of intracellular membrane transport proteins will be launched this coming summer. PMID:25795199

  10. TRP Channels and Analgesia

    PubMed Central

    Premkumar, Louis S.; Abooj, Mruvil

    2013-01-01

    Since cloning and characterizing the first nociceptive ion channel Transient Receptor Potential (TRP) Vanilloid 1 (TRPV1), other TRP channels involved in nociception have been cloned and characterized, which include TRP Vanilloid 2 (TRPV2), TRP Vanilloid 3 (TRPV3), TRP Vanilloid 4 (TRPV4), TRP Ankyrin 1 (TRPA1) and TRP Melastatin 8 (TRPM8), more recently TRP Canonical 1, 5, 6 (TRPC1, 5, 6), TRP Melastatin 2 (TRPM2) and TRP Melastatin 3 (TRPM3). These channels are predominantly expressed in C and Aδ nociceptors and transmit noxious thermal, mechanical and chemical sensitivities. TRP channels are modulated by pro-inflammatory mediators, neuropeptides and cytokines. Significant advances have been made targeting these receptors either by antagonists or agonists to treat painful conditions. In this review, we will discuss TRP channels as targets for next generation analgesics and the side effects that may ensue as a result of blocking/activating these receptors, because they are also involved in physiological functions such as release of vasoactive neuropeptides and regulation of vascular tone, maintenance of the body temperature, gastrointestinal motility, urinary bladder control etc. PMID:22910182

  11. MEMS in microfluidic channels.

    SciTech Connect

    Ashby, Carol Iris Hill; Okandan, Murat; Michalske, Terry A.; Sounart, Thomas L.; Matzke, Carolyn M.

    2004-03-01

    Microelectromechanical systems (MEMS) comprise a new class of devices that include various forms of sensors and actuators. Recent studies have shown that microscale cantilever structures are able to detect a wide range of chemicals, biomolecules or even single bacterial cells. In this approach, cantilever deflection replaces optical fluorescence detection thereby eliminating complex chemical tagging steps that are difficult to achieve with chip-based architectures. A key challenge to utilizing this new detection scheme is the incorporation of functionalized MEMS structures within complex microfluidic channel architectures. The ability to accomplish this integration is currently limited by the processing approaches used to seal lids on pre-etched microfluidic channels. This report describes Sandia's first construction of MEMS instrumented microfluidic chips, which were fabricated by combining our leading capabilities in MEMS processing with our low-temperature photolithographic method for fabricating microfluidic channels. We have explored in-situ cantilevers and other similar passive MEMS devices as a new approach to directly sense fluid transport, and have successfully monitored local flow rates and viscosities within microfluidic channels. Actuated MEMS structures have also been incorporated into microfluidic channels, and the electrical requirements for actuation in liquids have been quantified with an elegant theory. Electrostatic actuation in water has been accomplished, and a novel technique for monitoring local electrical conductivities has been invented.

  12. Channel Identification Machines

    PubMed Central

    Lazar, Aurel A.; Slutskiy, Yevgeniy B.

    2012-01-01

    We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s) onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS) with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits. PMID:23227035

  13. Pleasant events, unpleasant events, and depression.

    PubMed

    Sweeney, P D; Shaeffer, D E; Golin, S

    1982-07-01

    A review of previous research on Lewinsohn's model of depression shows that the causal link between a lack of response-contingent positive reinforcement and subsequent depression remains unsubstantiated. The present study was designed to explicitly test this causal relationship through the use of cross-lagged panel correlation. Measures of depression and pleasant events were taken at two different points in time separated by 1 month. The results revealed that the null hypothesis of spuriousness could not be rejected, indicating the relation often found between a lack of pleasant events and depression is probably due to some unmeasured third variable. The results also indicated that there is no causal relation between unpleasant events and depression. In summary, the causal assumptions in Lewinsohn's theory of depression were not supported by the data. Possible third-variable explanations of the data and their implications are discussed.

  14. Single sodium channels from the squid giant axon.

    PubMed Central

    Bezanilla, F

    1987-01-01

    Since the work of A. L. Hodgkin and A. F. Huxley (1952. J. Physiol. [Lond.].117:500-544) the squid giant axon has been considered the classical preparation for the study of voltage-dependent sodium and potassium channels. In this preparation much data have been gathered on macroscopic and gating currents but no single sodium channel data have been available. This paper reports patch clamp recording of single sodium channel events from the cut-open squid axon. It is shown that the single channel conductance in the absence of external divalent ions is approximately 14 pS, similar to sodium channels recorded from other preparations, and that their kinetic properties are consistent with previous results on gating and macroscopic currents obtained from the perfused squid axon preparation. PMID:2447971

  15. Precision measurement of top quark mass in dilepton channel

    SciTech Connect

    Jayatilaka, Bodhitha; /Michigan U.

    2006-01-01

    We present recent measurements of the top quark mass using events collected at the CDF and D0 detectors from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. These analyses are performed using events consistent with the decay channel t{bar t} {yields} {bar b}{ell}{sup -}{bar v}{sub {ell}}b{ell}' + v'{sub {ell}}, or the dilepton channel. 230-360 pb{sup -1} of data are used.

  16. Dequantization Via Quantum Channels

    NASA Astrophysics Data System (ADS)

    Andersson, Andreas

    2016-08-01

    For a unital completely positive map {Φ} ("quantum channel") governing the time propagation of a quantum system, the Stinespring representation gives an enlarged system evolving unitarily. We argue that the Stinespring representations of each power {Φ^m} of the single map together encode the structure of the original quantum channel and provide an interaction-dependent model for the bath. The same bath model gives a "classical limit" at infinite time {mto∞} in the form of a noncommutative "manifold" determined by the channel. In this way, a simplified analysis of the system can be performed by making the large-m approximation. These constructions are based on a noncommutative generalization of Berezin quantization. The latter is shown to involve very fundamental aspects of quantum-information theory, which are thereby put in a completely new light.

  17. Chaos in quantum channels

    NASA Astrophysics Data System (ADS)

    Hosur, Pavan; Qi, Xiao-Liang; Roberts, Daniel A.; Yoshida, Beni

    2016-02-01

    We study chaos and scrambling in unitary channels by considering their entanglement properties as states. Using out-of-time-order correlation functions to diagnose chaos, we characterize the ability of a channel to process quantum information. We show that the generic decay of such correlators implies that any input subsystem must have near vanishing mutual information with almost all partitions of the output. Additionally, we propose the negativity of the tripartite information of the channel as a general diagnostic of scrambling. This measures the delocalization of information and is closely related to the decay of out-of-time-order correlators. We back up our results with numerics in two non-integrable models and analytic results in a perfect tensor network model of chaotic time evolution. These results show that the butterfly effect in quantum systems implies the information-theoretic definition of scrambling.

  18. Chaos in quantum channels

    DOE PAGES

    Hosur, Pavan; Qi, Xiao-Liang; Roberts, Daniel A.; Yoshida, Beni

    2016-02-01

    For this research, we study chaos and scrambling in unitary channels by considering their entanglement properties as states. Using out-of-time-order correlation functions to diagnose chaos, we characterize the ability of a channel to process quantum information. We show that the generic decay of such correlators implies that any input subsystem must have near vanishing mutual information with almost all partitions of the output. Additionally, we propose the negativity of the tripartite information of the channel as a general diagnostic of scrambling. This measures the delocalization of information and is closely related to the decay of out-of-time-order correlators. We back upmore » our results with numerics in two non-integrable models and analytic results in a perfect tensor network model of chaotic time evolution. In conclusion, these results show that the butterfly effect in quantum systems implies the information-theoretic definition of scrambling.« less

  19. Dequantization Via Quantum Channels

    NASA Astrophysics Data System (ADS)

    Andersson, Andreas

    2016-10-01

    For a unital completely positive map {Φ} ("quantum channel") governing the time propagation of a quantum system, the Stinespring representation gives an enlarged system evolving unitarily. We argue that the Stinespring representations of each power {Φ^m} of the single map together encode the structure of the original quantum channel and provide an interaction-dependent model for the bath. The same bath model gives a "classical limit" at infinite time {mto∞} in the form of a noncommutative "manifold" determined by the channel. In this way, a simplified analysis of the system can be performed by making the large- m approximation. These constructions are based on a noncommutative generalization of Berezin quantization. The latter is shown to involve very fundamental aspects of quantum-information theory, which are thereby put in a completely new light.

  20. Entanglement-saving channels

    NASA Astrophysics Data System (ADS)

    Lami, L.; Giovannetti, V.

    2016-03-01

    The set of Entanglement Saving (ES) quantum channels is introduced and characterized. These are completely positive, trace preserving transformations which when acting locally on a bipartite quantum system initially prepared into a maximally entangled configuration, preserve its entanglement even when applied an arbitrary number of times. In other words, a quantum channel ψ is said to be ES if its powers ψn are not entanglement-breaking for all integers n. We also characterize the properties of the Asymptotic Entanglement Saving (AES) maps. These form a proper subset of the ES channels that is constituted by those maps that not only preserve entanglement for all finite n but which also sustain an explicitly not null level of entanglement in the asymptotic limit n → ∞. Structure theorems are provided for ES and for AES maps which yield an almost complete characterization of the former and a full characterization of the latter.

  1. Channel plate for DNA sequencing

    DOEpatents

    Douthart, R.J.; Crowell, S.L.

    1998-01-13

    This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface. 15 figs.

  2. Channel plate for DNA sequencing

    DOEpatents

    Douthart, Richard J.; Crowell, Shannon L.

    1998-01-01

    This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface.

  3. Solar impulsive energetic electron events

    NASA Astrophysics Data System (ADS)

    Wang, Linghua

    The Sun is capable of accelerating ions from ~ tens of keV up to tens of GeV and electrons from ~ tens of eV up to hundreds of MeVs in transient events such as flares and fast coronal mass ejections (CMEs). The energized particles escaping into the interplanetary medium are referred to as Solar Energetic Particle (SEP) events. The great majority of SEP events are impulsive SEP events that are dominated by ~1-100 keV electrons and ~MeV/nucleon ion emissions, with enhanced 3 He/ 4 He ratios up to 10 4 times the coronal values (also called electron/ 3 He-rich SEP events). This thesis is focused on solar impulsive energetic electron events, the electron part of impulsive SEP events, using electron observations from the 3-D Plasma and Energetic Particle instrument (3DP) on the WIND spacecraft near the Earth. First, I present the first comprehensive statistical study of solar energetic electron events over almost one solar cycle. I find that the occurrence rate of solar electron events shows a strong solar-cycle variation; after correction for the background effect, the estimated occurrence frequency exhibits a good power-law distribution, and the estimated occurrence rate near the Earth is ~1000/year at solar maximum and ~30/year at solar minimum for the instrumental sensitivity (~2.9×10^-4 (cm 2 s str eV) -1 for the 40 keV channel) of WIND/3DP, about one order of magnitude larger than the observed occurrence rate. Solar energetic electron events have a one-to-one association with type III radio bursts and a poor association with flares, but a close association with 3 He- rich ion emissions. These 3 He-rich electron events also have a poor association with flares but a close (~ 60%) association with west-limb CMEs. Then I present two case studies: one investigating the temporal relationship between solar impulsive electrons and type III radio emissions, and the second studying the temporal relationship between solar impulsive electrons and 3 He- rich ions. For both

  4. Psychiatric Disorders and TRP Channels: Focus on Psychotropic Drugs.

    PubMed

    Nazıroğlu, Mustafa; Demirdaş, Arif

    2015-01-01

    Psychiatric and neurological disorders are mostly associated with the changes in neural calcium ion signaling pathways required for activity-triggered cellular events. One calcium channel family is the TRP cation channel family, which contains seven subfamilies. Results of recent papers have discovered that calcium ion influx through TRP channels is important. We discuss the latest advances in calcium ion influx through TRP channels in the etiology of psychiatric disorders. Activation of TRPC4, TRPC5, and TRPV1 cation channels in the etiology of psychiatric disorders such as anxiety, fear-associated responses, and depression modulate calcium ion influx. Evidence substantiates that anandamide and its analog (methanandamide) induce an anxiolytic-like effect via CB1 receptors and TRPV1 channels. Intracellular calcium influx induced by oxidative stress has an significant role in the etiology of bipolar disorders (BDs), and studies recently reported the important role of TRP channels such as TRPC3, TRPM2, and TRPV1 in converting oxidant or nitrogen radical signaling to cytosolic calcium ion homeostasis in BDs. The TRPV1 channel also plays a function in morphine tolerance and hyperalgesia. Among psychotropic drugs, amitriptyline and capsazepine seem to have protective effects on psychiatric disorders via the TRP channels. Some drugs such as cocaine and methamphetamine also seem to have an important role in alcohol addiction and substance abuse via activation of the TRPV1 channel. Thus, we explore the relationships between the etiology of psychiatric disorders and TRP channel-regulated mechanisms. Investigation of the TRP channels in psychiatric disorders holds the promise of the development of new drug treatments. PMID:26411768

  5. Psychiatric Disorders and TRP Channels: Focus on Psychotropic Drugs

    PubMed Central

    Nazıroğlu, Mustafa; Demirdaş, Arif

    2015-01-01

    Psychiatric and neurological disorders are mostly associated with the changes in neural calcium ion signaling pathways required for activity-triggered cellular events. One calcium channel family is the TRP cation channel family, which contains seven subfamilies. Results of recent papers have discovered that calcium ion influx through TRP channels is important. We discuss the latest advances in calcium ion influx through TRP channels in the etiology of psychiatric disorders. Activation of TRPC4, TRPC5, and TRPV1 cation channels in the etiology of psychiatric disorders such as anxiety, fear-associated responses, and depression modulate calcium ion influx. Evidence substantiates that anandamide and its analog (methanandamide) induce an anxiolytic-like effect via CB1 receptors and TRPV1 channels. Intracellular calcium influx induced by oxidative stress has an significant role in the etiology of bipolar disorders (BDs), and studies recently reported the important role of TRP channels such as TRPC3, TRPM2, and TRPV1 in converting oxidant or nitrogen radical signaling to cytosolic calcium ion homeostasis in BDs. The TRPV1 channel also plays a function in morphine tolerance and hyperalgesia. Among psychotropic drugs, amitriptyline and capsazepine seem to have protective effects on psychiatric disorders via the TRP channels. Some drugs such as cocaine and methamphetamine also seem to have an important role in alcohol addiction and substance abuse via activation of the TRPV1 channel. Thus, we explore the relationships between the etiology of psychiatric disorders and TRP channel-regulated mechanisms. Investigation of the TRP channels in psychiatric disorders holds the promise of the development of new drug treatments. PMID:26411768

  6. Sodium channels and pain.

    PubMed

    Habib, Abdella M; Wood, John N; Cox, James J

    2015-01-01

    Human and mouse genetic studies have led to significant advances in our understanding of the role of voltage-gated sodium channels in pain pathways. In this chapter, we focus on Nav1.7, Nav1.8, Nav1.9 and Nav1.3 and describe the insights gained from the detailed analyses of global and conditional transgenic Nav knockout mice in terms of pain behaviour. The spectrum of human disorders caused by mutations in these channels is also outlined, concluding with a summary of recent progress in the development of selective Nav1.7 inhibitors for the treatment of pain. PMID:25846613

  7. Zeolites: Exploring Molecular Channels

    SciTech Connect

    Arslan, Ilke; Derewinski, Mirek

    2015-05-22

    Synthetic zeolites contain microscopic channels, sort of like a sponge. They have many uses, such as helping laundry detergent lather, absorbing liquid in kitty litter, and as catalysts to produce fuel. Of the hundreds of types of zeolites, only about 15 are used for catalysis. PNNL catalysis scientists Ilke Arslan and Mirek Derewinksi are studying these zeolites to understand what make them special. By exploring the mystery of these microscopic channels, their fundamental findings will help design better catalysts for applications such as biofuel production.

  8. Dialogue on private events

    PubMed Central

    Palmer, David C.; Eshleman, John; Brandon, Paul; Layng, T. V. Joe; McDonough, Christopher; Michael, Jack; Schoneberger, Ted; Stemmer, Nathan; Weitzman, Ray; Normand, Matthew

    2004-01-01

    In the fall of 2003, the authors corresponded on the topic of private events on the listserv of the Verbal Behavior Special Interest Group. Extracts from that correspondence raised questions about the role of response amplitude in determining units of analysis, whether private events can be investigated directly, and whether covert behavior differs from other behavior except in amplitude. Most participants took a cautious stance, noting not only conceptual pitfalls and empirical difficulties in the study of private events, but doubting the value of interpretive exercises about them. Others argued that despite such obstacles, in domains where experimental analyses cannot be done, interpretation of private events in the light of laboratory principles is the best that science can offer. One participant suggested that the notion that private events can be behavioral in nature be abandoned entirely; as an alternative, the phenomena should be reinterpreted only as physiological events. PMID:22477293

  9. Micromechanisms of brittle fracture: Acoustic emissions and electron channeling analyses

    SciTech Connect

    Gerberich, W.W.

    1990-06-01

    The objectives of this work are to: (i) Evaluate the initial stages of cleavage nucleation in single and polycrystalline samples; (ii) Determine the controlling event(s) which lead(s) to unstable cleavage (is it an unstable cluster'' of microcracks or a crack-tip opening displacement criterion for an array of ligaments surrounding these microcracks ); (iii) Determine how the process zone, which depends upon microstructure and processing history, affects the controlling event(s); (iv) Use selected area channeling patterns (SACP's) to assist in an independent measure of the cleavage fracture stress of grains cleaved at or just outside the elastic-plastic boundary; also, use it to evaluate static and dynamic strain distributions; and (v) Evaluate the effects of dislocation shielding and overload using combined methods of computational mechanics with discretized dislocation arrays and direct observations of dislocations using channeling, etch pit and birefringence methods. Accomplishments are discussed. 15 refs., 3 figs.

  10. Channels of Propaganda.

    ERIC Educational Resources Information Center

    Sproule, J. Michael

    Defining propaganda as "efforts by special interests to win over the public covertly by infiltrating messages into various channels of public expression ordinarily viewed as politically neutral," this book argues that propaganda has become pervasive in American life. Pointing out that the 1990s society is inundated with propaganda from numerous…

  11. Learning in Tactile Channels

    ERIC Educational Resources Information Center

    Gescheider, George A.; Wright, John H.

    2012-01-01

    Vibrotactile intensity-discrimination thresholds for sinusoidal stimuli applied to the thenar eminence of the hand declined as a function of practice. However, improvement was confined to the tactile information-processing channel in which learning had occurred. Specifically, improvements in performance with training within the Pacinian-corpuscle…

  12. SK channels and calmodulin.

    PubMed

    Adelman, John P

    2016-01-01

    Calcium ions are Nature's most widely used signaling mechanism, mediating communication between pathways at virtually every physiological level. Ion channels are no exception, as the activities of a wide range of ion channels are intricately shaped by fluctuations in intracellular Ca(2+) levels. Mirroring the importance and the breadth of Ca(2+) signaling, free Ca(2+) levels are tightly controlled, and a myriad of Ca(2+) binding proteins transduce Ca(2+) signals, each with its own nuance, comprising a constantly changing symphony of metabolic activity. The founding member of Ca(2+) binding proteins is calmodulin (CaM), a small, acidic, modular protein endowed with gymnastic-like flexibility and E-F hand motifs that chelate Ca(2+) ions. In this review, I will trace the history that led to the realization that CaM serves as the Ca(2+)-gating cue for SK channels, the experiments that revealed that CaM is an intrinsic subunit of SK channels, and itself a target of regulation. PMID:25942650

  13. Chemistry in Microfluidic Channels

    ERIC Educational Resources Information Center

    Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

    2011-01-01

    General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

  14. Developments in relativistic channeling

    SciTech Connect

    Carrigan, R.A. Jr.

    1996-10-01

    The possibility of using channeling as a tool for high energy accelerator applications and particle physics has now been extensively investigated. Bent crystals have been used for accelerator extraction and for particle deflection. Applications as accelerating devices have been discussed but have not yet been tried. 61 refs., 1 fig.

  15. Channeling through Bent Crystals

    SciTech Connect

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to

  16. Features, Events, and Processes: Disruptive Events

    SciTech Connect

    J. King

    2004-03-31

    The primary purpose of this analysis is to evaluate seismic- and igneous-related features, events, and processes (FEPs). These FEPs represent areas of natural system processes that have the potential to produce disruptive events (DE) that could impact repository performance and are related to the geologic processes of tectonism, structural deformation, seismicity, and igneous activity. Collectively, they are referred to as the DE FEPs. This evaluation determines which of the DE FEPs are excluded from modeling used to support the total system performance assessment for license application (TSPA-LA). The evaluation is based on the data and results presented in supporting analysis reports, model reports, technical information, or corroborative documents that are cited in the individual FEP discussions in Section 6.2 of this analysis report.

  17. Diminishing blocking interval in particle-conveying channel bundles

    NASA Astrophysics Data System (ADS)

    Barré, Chloé; Talbot, Julian

    2016-09-01

    We consider a channel bundle consisting of N c parallel channels conveying a particulate flux. Particles enter these channels according to a homogeneous Poisson process and exit after a fixed transit time, τ. An individual channel blocks if N particles are simultaneously present. When a channel is blocked the flux previously entering it is redistributed evenly over the remaining open channels. We perform event driven simulations to examine the behaviour of an initially empty channel bundle with a total entering flux of intensity Λ. The mean blockage time of the kth channel is denoted by ⟨ t k ⟩ ,k = 1 , ... , N c . For N = 1, as shown previously, the interval between successive blockages is constant, while for N > 1 an accelerating cascade, i.e. one in which the interval between successive blockages decreases, is observed. After an initial transient regime we observe a well-defined universal regime that is characterized by Δ_k^{(N)} = (-1)^{N-1}[(N-1)!]^2/(Λτ)^N Δ k ( N ) = ( - 1 ) N - 1 [ ( N - 1 ) ! ] 2 ( Λ τ ) N where Δ_k^{(1)}=< t_k rangle-< t_{k-1}rangle}Δk(1)=⟨tk⟩-⟨tk-1⟩ and {Δ_k^{(j)}=Δ_k^{(j-1)}-Δ_{k-1}^{(j-1)}Δk(j)=Δk(j-1)-Δk-1(j-1) denotes the jth order difference.

  18. Implications of Historic River Channel Modifications on Contemporary Restoration Opportunities

    NASA Astrophysics Data System (ADS)

    Hanrahan, T. P.

    2013-12-01

    Identifying contemporary river management and restoration opportunities relies on understanding how river ecosystems respond to historic forcing from natural events and human impacts. Over the past 70 years, the Big Wood River in central Idaho, USA, has experienced significant engineered channel modifications and realignment, as well as natural changes in channel location and riverbank instability. Understanding the effects of these historic conditions on contemporary river characteristics and processes was needed to inform river management and restoration planning. A geomorphic assessment along 16 km of the Big Wood River was completed in order to understand the physical characteristics and processes upstream, within, and downstream of a 3 km long project reach. This evaluation included analysis of the longitudinal profile, planform pattern, cross-section dimensions, cross-section hydraulics, riverbed and riverbank materials, sediment transport conditions, and large roughness elements such as boulders and large wood material. As a result of residential and highway encroachment along the river corridor, river channel modifications (bank revetments, grade-control drop structures, training channels, sediment traps) have been implemented in attempts to limit the vertical and lateral channel adjustments that would negatively affect infrastructure along the river corridor. These river channel modifications have interrupted the geomorphic processes of the Big Wood River, and have initiated the need for ongoing maintenance of in-channel structures and new efforts at river restoration. Future river ecosystem response along this reach of the Big Wood River will be constrained as a result of river channel and floodplain modifications throughout the valley.

  19. Features, Events, and Processes: Disruptive Events

    SciTech Connect

    P. Sanchez

    2004-11-08

    The purpose of this analysis report is to evaluate and document the inclusion or exclusion of the disruptive events features, events, and processes (FEPs) with respect to modeling used to support the total system performance assessment for license application (TSPA-LA). A screening decision, either ''Included'' or ''Excluded,'' is given for each FEP, along with the technical basis for screening decisions. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.114 (d), (e), and (f) [DIRS 156605]. The FEPs addressed in this report deal with both seismic and igneous disruptive events, such as fault displacements through the repository and an igneous intrusion into the repository. For included FEPs, this analysis summarizes the implementation of the FEP in TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded). Previous versions of this report were developed to support the total system performance assessments (TSPA) for various prior repository designs. This revision addresses the repository design for the license application (LA).

  20. Committed Sport Event Volunteers

    ERIC Educational Resources Information Center

    Han, Keunsu; Quarterman, Jerome; Strigas, Ethan; Ha, Jaehyun; Lee, Seungbum

    2013-01-01

    The purpose of this study was to investigate the relationships among selected demographic characteristics (income, education and age), motivation and commitment of volunteers at a sporting event. Three-hundred and five questionnaires were collected from volunteers in a marathon event and analyzed using structural equation modeling (SEM). Based on…

  1. Activating Event Knowledge

    ERIC Educational Resources Information Center

    Hare, Mary; Jones, Michael; Thomson, Caroline; Kelly, Sarah; McRae, Ken

    2009-01-01

    An increasing number of results in sentence and discourse processing demonstrate that comprehension relies on rich pragmatic knowledge about real-world events, and that incoming words incrementally activate such knowledge. If so, then even outside of any larger context, nouns should activate knowledge of the generalized events that they denote or…

  2. Traumatic events and children

    MedlinePlus

    ... a one-time traumatic event or a repeated trauma that happens over and over again. Examples of one-time traumatic events are: Natural disasters, such as a tornado, hurricane, fire, or flood Rape Witness shooting or stabbing of a person Sudden ...

  3. Single Channel Activity from Ion Channels in Engineered Tethered Bilayer Membrane Arrays

    NASA Astrophysics Data System (ADS)

    Keizer, Henk; Fine, Daniel; K"{O}Per, Ingo; Anderson, Peter

    2005-11-01

    The demand for rapid in situ detection of chemical and biological analytes at high sensitivity has increased interest in the development of biosensors like the commercially available compact glucose sensor. Engineered membrane bound ion channels are promising biological receptors since they would allow for the stochastic detection of analytes at high sensitivity, they can be mutated to alter sensitivity, and they produce a well-defined read-out that is inherently suitable for digitization. In order to perform stochastic sensing it is necessary to be able to measure the ion currents associated with single ion channel opening and closing events. Although sensors based on supported bilayers containing various pore forming proteins have been described, none of these systems have recorded single channel activity. Here we describe the measurement of stochastic activity from synthetic single ion channels, based on the nicotinic acetylcholine receptor (nAChR) from Torpedo californica, inserted into individual pixels of a microelectrode array device. The limited size of the gold sense pad surface, 100x100 μm, and the electrical stability of the overlying lipid bilayer membrane make each pixel sensitive enough to measure single ion channel currents in the picoampere range.

  4. Serine protease activation of near-silent epithelial Na+ channels.

    PubMed

    Caldwell, Ray A; Boucher, Richard C; Stutts, M Jackson

    2004-01-01

    The regulation of epithelial Na+ channel (ENaC) function is critical for normal salt and water balance. This regulation is achieved through cell surface insertion/retrieval of channels, by changes in channel open probability (Po), or through a combination of these processes. Epithelium-derived serine proteases, including channel activating protease (CAP) and prostasin, regulate epithelial Na+ transport, but the molecular mechanism is unknown. We tested the hypothesis that extracellular serine proteases activate a near-silent ENaC population resident in the plasma membrane. Single-channel events were recorded in outside-out patches from fibroblasts (NIH/3T3) stably expressing rat alpha-, beta-, and gamma-subunits (rENaC), before and during exposure to trypsin, a serine protease homologous to CAP and prostasin. Under baseline conditions, near-silent patches were defined as having rENaC activity (NPo) < 0.03, where N is the number of channels. Within 1-5 min of 3 microg/ml bath trypsin superfusion, NPo increased approximately 66-fold (n = 7). In patches observed to contain a single functional channel, trypsin increased Po from 0.02 +/- 0.01 to 0.57 +/- 0.03 (n = 3, mean +/- SE), resulting from the combination of an increased channel open time and decreased channel closed time. Catalytic activity was required for activation of near-silent ENaC. Channel conductance and the Na+/Li+ current ratio with trypsin were similar to control values. Modulation of ENaC Po by endogenous epithelial serine proteases is a potentially important regulator of epithelial Na+ transport, distinct from the regulation achieved by hormone-induced plasma membrane insertion of channels. PMID:12967915

  5. Contrasting Large Solar Events

    NASA Astrophysics Data System (ADS)

    Lanzerotti, Louis J.

    2010-10-01

    After an unusually long solar minimum, solar cycle 24 is slowly beginning. A large coronal mass ejection (CME) from sunspot 1092 occurred on 1 August 2010, with effects reaching Earth on 3 August and 4 August, nearly 38 years to the day after the huge solar event of 4 August 1972. The prior event, which those of us engaged in space research at the time remember well, recorded some of the highest intensities of solar particles and rapid changes of the geomagnetic field measured to date. What can we learn from the comparisons of these two events, other than their essentially coincident dates? One lesson I took away from reading press coverage and Web reports of the August 2010 event is that the scientific community and the press are much more aware than they were nearly 4 decades ago that solar events can wreak havoc on space-based technologies.

  6. The elusive character of discontinuous deep-water channels: New insights from Lucia Chica channel system, offshore California

    USGS Publications Warehouse

    Maier, K.L.; Fildani, A.; Paull, C.K.; Graham, S.A.; McHargue, T.R.; Caress, D.W.; McGann, M.

    2011-01-01

    New high-resolution autonomous underwater vehicle (AUV) seafloor images, with 1 m lateral resolution and 0.3 m vertical resolution, reveal unexpected seafloor rugosity and low-relief (<10 m), discontinuous conduits over ~70 km2. Continuous channel thalwegs were interpreted originally from lower-resolution images, but newly acquired AUV data indicate that a single sinuous channel fed a series of discontinuous lower-relief channels. These discontinuous channels were created by at least four avulsion events. Channel relief, defined as the height from the thalweg to the levee crest, controls avulsions and overall stratigraphic architecture of the depositional area. Flowstripped turbidity currents separated into and reactivated multiple channels to create a distributary pattern and developed discontinuous trains of cyclic scours and megaflutes, which may be erosional precursors to continuous channels. The diverse features now imaged in the Lucia Chica channel system (offshore California) are likely common in modern and ancient systems with similar overall morphologies, but have not been previously mapped with lower-resolution detection methods in any of these systems. ?? 2011 Geological Society of America.

  7. Learning Channels and Verbal Behavior

    ERIC Educational Resources Information Center

    Lin, Fan-Yu; Kubina, Richard M., Jr.

    2004-01-01

    This article reviews the basics of learning channels and how specification of stimuli can help enhance verbal behavior. This article will define learning channels and the role of the ability matrix in training verbal behavior.

  8. Cloning and expression of a FMRFamide-gated Na+ channel from Helisoma trivolvis and comparison with the native neuronal channel

    PubMed Central

    Jeziorski, Michael C; Green, Kevin A; Sommerville, John; Cottrell, Glen A

    2000-01-01

    We have cloned a cDNA encoding a Phe-Met-Arg-Phe-NH2 (FMRFamide)-gated Na+ channel from nervous tissue of the pond snail Helisoma trivolvis (HtFaNaC) and expressed the channel in Xenopus oocytes. The deduced amino acid sequence of the protein expressed by HtFaNaC is 65 % identical to that of the FMRFamide-gated channel cloned from Helix aspersa (HaFaNaC). HtFaNaC expressed in oocytes was less sensitive to FMRFamide (EC50 = 70 μM) than HaFaNaC (EC50 = 2 μM). The two had a similar selectivity for Na+. The amplitude of the FMRFamide response of HtFaNaC was increased by reducing the extracellular concentration of divalent cations. The conductance of the two channels was similar, but the mean open time of unitary events was shorter for expressed HtFaNaC compared to expressed HaFaNaC. Each channel was susceptible to peptide block by high agonist concentrations. In marked contrast to HaFaNaC and other amiloride-sensitive Na+ channels, amiloride, and the related drugs benzamil and 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), enhanced the FMRFamide response in oocytes expressing HtFaNaC cRNA. The potentiating effects of EIPA and benzamil were greater than those of amiloride. Unitary current analysis showed that with such drugs, there was channel blockade as well as an increased probability of channel opening. The similar permeability of the oocyte-expressed HtFaNaC and the Helisoma neuronal channel, and the susceptibility of both to agonist blockade and blockade by divalent cations, suggest that the channels are the same. However, neuronal channels were less susceptible to enhancement by amiloride analogues and in some patches were more sensitive to FMRFamide than expressed HtFaNaC. PMID:10878095

  9. Fluid channeling system

    NASA Technical Reports Server (NTRS)

    Davis, Donald Y. (Inventor); Hitch, Bradley D. (Inventor)

    1994-01-01

    A fluid channeling system includes a fluid ejector, a heat exchanger, and a fluid pump disposed in series flow communication The ejector includes a primary inlet for receiving a primary fluid, and a secondary inlet for receiving a secondary fluid which is mixed with the primary fluid and discharged therefrom as ejector discharge. Heat is removed from the ejector discharge in the heat exchanger, and the heat exchanger discharge is compressed in the fluid pump and channeled to the ejector secondary inlet as the secondary fluid In an exemplary embodiment, the temperature of the primary fluid is greater than the maximum operating temperature of a fluid motor powering the fluid pump using a portion of the ejector discharge, with the secondary fluid being mixed with the primary fluid so that the ejector discharge temperature is equal to about the maximum operating temperature of the fluid motor.

  10. Geysering in boiling channels

    SciTech Connect

    Aritomi, Masanori; Takemoto, Takatoshi; Chiang, Jing-Hsien

    1995-09-01

    A concept of natural circulation BWRs such as the SBWR has been proposed and seems to be promising in that the primary cooling system can be simplified. The authors have been investigating thermo-hydraulic instabilities which may appear during the start-up in natural circulation BWRs. In our previous works, geysering was investigated in parallel boiling channels for both natural and forced circulations, and its driving mechanism and the effect of system pressure on geysering occurrence were made clear. In this paper, geysering is investigated in a vertical column and a U-shaped vertical column heated in the lower parts. It is clarified from the results that the occurrence mechanism of geysering and the dependence of system pressure on geysering occurrence coincide between parallel boiling channels in circulation systems and vertical columns in non-circulation systems.

  11. Athermal channeled spectropolarimeter

    SciTech Connect

    Jones, Julia Craven

    2015-12-08

    A temperature insensitive (athermal) channeled spectropolarimeter (CSP) is described. The athermal CSP includes a crystal retarder formed of a biaxial crystal. The crystal retarder has three crystal axes, wherein each axis has its own distinct index of refraction. The axes are oriented in a particular manner, causing an amplitude modulating carrier frequency induced by the crystal retarder to be thermally invariant. Accordingly, a calibration beam technique can be used over a relatively wide range of ambient temperatures, with a common calibration data set.

  12. Aquaglyceroporins: generalized metalloid channels

    PubMed Central

    Mukhopadhyay, Rita; Bhattacharjee, Hiranmoy; Rosen, Barry P.

    2014-01-01

    Background: Aquaporins (AQPs), members of a superfamily of transmembrane channel proteins, are ubiquitous in all domains of life. They fall into a number of branches that can be functionally categorized into two major sub-groups: i) orthodox aquaporins, which are water-specific channels, and ii) aquaglyceroporins, which allow the transport of water, non-polar solutes, such as urea or glycerol, the reactive oxygen species hydrogen peroxide, and gases such as ammonia, carbon dioxide and nitric oxide and, as described in this review, metalloids. Scope of Review: This review summarizes the key findings that AQP channels conduct bidirectional movement of metalloids into and out of cells. Major Conclusions: As(OH)3 and Sb(OH)3 behave as inorganic molecular mimics of glycerol, a property that allows their passage through AQP channels. Plant AQPs also allow the passage of boron and silicon as their hydroxyacids, boric acid (B(OH)3) and orthosilicic acid (Si(OH)4), respectively. Genetic analysis suggests that germanic acid (GeO2) is also a substrate. While As(III), Sb(III) and Ge(IV) are toxic metalloids, borate (B(III)) and silicate (Si(IV)) are essential elements in higher plants. General Significance: The uptake of environmental metalloids by aquaporins provides an understanding of (i) how toxic elements such as arsenic enter the food chain; (ii) the delivery of arsenic and antimony containing drugs in the treatment of certain forms of leukemia and chemotherapy of diseases caused by pathogenic protozoa; and (iii) the possibility that food plants such as rice could be made safer by genetically modifying them to exclude arsenic while still accumulating boron and silicon. PMID:24291688

  13. Radar channel balancing with commutation

    SciTech Connect

    Doerry, Armin Walter

    2014-02-01

    When multiple channels are employed in a pulse-Doppler radar, achieving and maintaining balance between the channels is problematic. In some circumstances the channels may be commutated to achieve adequate balance. Commutation is the switching, trading, toggling, or multiplexing of the channels between signal paths. Commutation allows modulating the imbalance energy away from the balanced energy in Doppler, where it can be mitigated with filtering.

  14. Ion channeling revisited

    SciTech Connect

    Doyle, Barney Lee; Corona, Aldo; Nguyen, Anh

    2014-09-01

    A MS Excel program has been written that calculates accidental, or unintentional, ion channeling in cubic bcc, fcc and diamond lattice crystals or polycrystalline materials. This becomes an important issue when simulating the creation by energetic neutrons of point displacement damage and extended defects using beams of ions. All of the tables and graphs in the three Ion Beam Analysis Handbooks that previously had to be manually looked up and read from were programed into Excel in handy lookup tables, or parameterized, for the case of the graphs, using rather simple exponential functions with different powers of the argument. The program then offers an extremely convenient way to calculate axial and planar half-angles and minimum yield or dechanneling probabilities, effects on half-angles of amorphous overlayers, accidental channeling probabilities for randomly oriented crystals or crystallites, and finally a way to automatically generate stereographic projections of axial and planar channeling half-angles. The program can generate these projections and calculate these probabilities for axes and [hkl] planes up to (555).

  15. The alpha channeling effect

    SciTech Connect

    Fisch, N. J.

    2015-12-10

    Alpha particles born through fusion reactions in a tokamak reactor tend to slow down on electrons, but that could take up to hundreds of milliseconds. Before that happens, the energy in these alpha particles can destabilize on collisionless timescales toroidal Alfven modes and other waves, in a way deleterious to energy confinement. However, it has been speculated that this energy might be instead be channeled into useful energy, so as to heat fuel ions or to drive current. Such a channeling needs to be catalyzed by waves Waves can produce diffusion in energy of the alpha particles in a way that is strictly coupled to diffusion in space. If these diffusion paths in energy-position space point from high energy in the center to low energy on the periphery, then alpha particles will be cooled while forced to the periphery. The energy from the alpha particles is absorbed by the wave. The amplified wave can then heat ions or drive current. This process or paradigm for extracting alpha particle energy collisionlessly has been called alpha channeling. While the effect is speculative, the upside potential for economical fusion is immense. The paradigm also operates more generally in other contexts of magnetically confined plasma.

  16. Micro-channel plate detector

    SciTech Connect

    Elam, Jeffrey W.; Lee, Seon W.; Wang, Hsien -Hau; Pellin, Michael J.; Byrum, Karen; Frisch, Henry J.

    2015-09-22

    A method and system for providing a micro-channel plate detector. An anodized aluminum oxide membrane is provided and includes a plurality of nanopores which have an Al coating and a thin layer of an emissive oxide material responsive to incident radiation, thereby providing a plurality of radiation sensitive channels for the micro-channel plate detector.

  17. Cascading blockages in channel bundles.

    PubMed

    Barré, C; Talbot, J

    2015-11-01

    Flow in channel networks may involve a redistribution of flux following the blockage or failure of an individual link. Here we consider a simplified model consisting of N(c) parallel channels conveying a particulate flux. Particles enter these channels according to a homogeneous Poisson process and an individual channel blocks if more than N particles are simultaneously present. The behavior of the composite system depends strongly on how the flux of entering particles is redistributed following a blockage. We consider two cases. In the first, the intensity on each open channel remains constant while in the second the total intensity is evenly redistributed over the open channels. We obtain exact results for arbitrary N(c) and N for a system of independent channels and for arbitrary N(c) and N=1 for coupled channels. For N>1 we present approximate analytical as well as numerical results. Independent channels block at a decreasing rate due to a simple combinatorial effect, while for coupled channels the interval between successive blockages remains constant for N=1 but decreases for N>1. This accelerating cascade is due to the nonlinear dependence of the mean blocking time of a single channel on the entering particle flux that more than compensates for the decrease in the number of active channels.

  18. Event Pileup in AXAF's ACIS CCD Camera

    NASA Technical Reports Server (NTRS)

    McNamara, Brian R.

    1998-01-01

    AXAF's high resolution mirrors will focus a point source near the optical axis to a spot that is contained within a radius of about two pixels on the ACIS Charge Coupled Devices (CCD) camera. Because of the small spot size, the accuracy to which fluxes and spectral energy distributions of bright point sources can be measured will be degrad3ed by event pileup. Event pileup occurs when two or more X-ray photons arrive simultaneously in a single detection cell on a CCD readout frame. When pileup occurs, ACIS's event detection algorithm registers the photons as a single X-ray event. The pulse height channel of the event will correspond to an energy E approximately E-1 + E-2...E-n, where n is the number of photons registered per detection cell per readout frame. As a result, pileup artificially hardens the observed spectral energy distribution. I will discuss the effort at the AXAF Science Center Lo calibrate pileup in ACIS using focused, nearly monochromatic X-ray source. I will discuss techniques for modeling and correcting pileup effects in polychromatic spectra.

  19. Safeguards Summary Event List (SSEL). Pre-NRC-June 30, 1985. Revision 11

    SciTech Connect

    Not Available

    1986-01-01

    The Safeguards Summary Event List (SSRL) provides brief summaries of several hundred safeguards-related events involving nuclear material or facilities regulated by the US Nuclear Regulatory Commission (NRC). Events are described under the categories of bomb-related, intrusion, missing and/or allegedly stolen, transportation, tampering/vandalism, arson, firearms, radiological sabotage, non-radiological sabotage and miscellaneous. The information contained in the event descriptions is derived primarily from official NRC reporting channels. 12 figs.

  20. Safeguards Summary Event List (SSEL). Pre-NRC through December 31, 1984. Revision 10

    SciTech Connect

    Not Available

    1985-05-01

    The Safeguards Summary Event List (SSEL) provides brief summaries of several hundred safeguards-related events involving nuclear material or facilities regulated by the US Nuclear Regulatory Commission (NRC). Events are described under the categories of bomb-related, intrusion, missing and/or allegedly stolen, transportation, tampering/vandalism, arson, firearms, radiological sabotage, non-radiological sabotage and miscellaneous. The information contained in the event descriptions in derived primarily from official NRC reporting channels.

  1. Safeguards Summary Event List (SSEL), Pre-NRC through December 31, 1983. Rev. 9

    SciTech Connect

    Not Available

    1984-06-01

    The Safeguards Summary Event List (SSEL) provides brief summaries of several hundred safeguards-related events involving nuclear material or facilities regulated by the US Nuclear Regulatory Commission (NRC). Events are described under the categories of bomb-related, intrusion, missing/allegedly stolen, transportation, tampering/vandalism, arson, firearms-related, radiological sabotage and miscellaneous. The information contained in the event descriptions is derived primarily from official NRC reporting channels.

  2. Safeguards summary event list (SSEL): Pre-NRC through December 31, 1987

    SciTech Connect

    Not Available

    1988-07-01

    The Safeguards Summary Event List (SSEL) provides brief summaries of several hundred safeguards-related events involving nuclear material or facilities regulated by the US Nuclear Regulatory Commission (NRC). Events are described under the categories of bomb-related, intrusion, missing and/or allegedly stolen, transportation, tampering/vandalism, arson, firearms, radiological sabotage, nonradiological sabotage, alcohol and drugs, and miscellaneous. The information contained in the event descriptions is derived primarily from official NRC reporting channels.

  3. A Micromechanical RF Channelizer

    NASA Astrophysics Data System (ADS)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  4. Event shape sorting

    NASA Astrophysics Data System (ADS)

    Kopečná, Renata; Tomášik, Boris

    2016-04-01

    We propose a novel method for sorting events of multiparticle production according to the azimuthal anisotropy of their momentum distribution. Although the method is quite general, we advocate its use in analysis of ultra-relativistic heavy-ion collisions where a large number of hadrons is produced. The advantage of our method is that it can automatically sort out samples of events with histograms that indicate similar distributions of hadrons. It takes into account the whole measured histograms with all orders of anisotropy instead of a specific observable ( e.g., v_2 , v_3 , q_2 . It can be used for more exclusive experimental studies of flow anisotropies which are then more easily compared to theoretical calculations. It may also be useful in the construction of mixed-events background for correlation studies as it allows to select events with similar momentum distribution.

  5. Special Event Production.

    ERIC Educational Resources Information Center

    Currents, 2002

    2002-01-01

    Offers a descriptive table of software that helps higher education institutions orchestrate events. Information includes vendor, contact, software, price, database engine/server platform, specific features, and client type. (EV)

  6. CCG - News & Events

    Cancer.gov

    NCI's Center for Cancer Genomics (CCG) has been widely recognized for its research efforts to facilitiate advances in cancer genomic research and improve patient outcomes. Find the latest news about and events featuring CCG.

  7. Holter and Event Monitors

    MedlinePlus

    ... Holter and event monitors are similar to an EKG (electrocardiogram). An EKG is a simple test that detects and records ... for diagnosing heart rhythm problems. However, a standard EKG only records the heartbeat for a few seconds. ...

  8. RAS Initiative - Events

    Cancer.gov

    The NCI RAS Initiative has organized multiple events with outside experts to discuss how the latest scientific and technological breakthroughs can be applied to discover vulnerabilities in RAS-driven cancers.

  9. "Universe" event at AIMS

    NASA Astrophysics Data System (ADS)

    2008-06-01

    Report of event of 11 May 2008 held at the African Institute of Mathematical Sciences (Muizenberg, Cape), with speakers Michael Griffin (Administrator of NASA), Stephen Hawking (Cambridge), David Gross (Kavli Institute, Santa Barbara) and George Smoot (Berkeley).

  10. QCD (&) event generators

    SciTech Connect

    Skands, Peter Z.; /Fermilab

    2005-07-01

    Recent developments in QCD phenomenology have spurred on several improved approaches to Monte Carlo event generation, relative to the post-LEP state of the art. In this brief review, the emphasis is placed on approaches for (1) consistently merging fixed-order matrix element calculations with parton shower descriptions of QCD radiation, (2) improving the parton shower algorithms themselves, and (3) improving the description of the underlying event in hadron collisions.

  11. Activating Event Knowledge

    PubMed Central

    Hare, Mary; Jones, Michael; Thomson, Caroline; Kelly, Sarah; McRae, Ken

    2009-01-01

    An increasing number of results in sentence and discourse processing demonstrate that comprehension relies on rich pragmatic knowledge about real-world events, and that incoming words incrementally activate such knowledge. If so, then even outside of any larger context, nouns should activate knowledge of the generalized events that they denote or typically play a role in. We used short stimulus onset asynchrony priming to demonstrate that (1) event nouns prime people (sale-shopper) and objects (trip-luggage) commonly found at those events; (2) location nouns prime people/animals (hospital-doctor) and objects (barn-hay) commonly found at those locations; and (3) instrument nouns prime things on which those instruments are commonly used (key-door), but not the types of people who tend to use them (hose-gardener). The priming effects are not due to normative word association. On our account, facilitation results from event knowledge relating primes and targets. This has much in common with computational models like LSA or BEAGLE in which one word primes another if they frequently occur in similar contexts. LSA predicts priming for all six experiments, whereas BEAGLE correctly predicted that priming should not occur for the instrument-people relation but should occur for the other five. We conclude that event-based relations are encoded in semantic memory and computed as part of word meaning, and have a strong influence on language comprehension. PMID:19298961

  12. 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.

  13. Seismic event classification system

    DOEpatents

    Dowla, Farid U.; Jarpe, Stephen P.; Maurer, William

    1994-01-01

    In the computer interpretation of seismic data, the critical first step is to identify the general class of an unknown event. For example, the classification might be: teleseismic, regional, local, vehicular, or noise. Self-organizing neural networks (SONNs) can be used for classifying such events. Both Kohonen and Adaptive Resonance Theory (ART) SONNs are useful for this purpose. Given the detection of a seismic event and the corresponding signal, computation is made of: the time-frequency distribution, its binary representation, and finally a shift-invariant representation, which is the magnitude of the two-dimensional Fourier transform (2-D FFT) of the binary time-frequency distribution. This pre-processed input is fed into the SONNs. These neural networks are able to group events that look similar. The ART SONN has an advantage in classifying the event because the types of cluster groups do not need to be pre-defined. The results from the SONNs together with an expert seismologist's classification are then used to derive event classification probabilities.

  14. Seismic event classification system

    DOEpatents

    Dowla, F.U.; Jarpe, S.P.; Maurer, W.

    1994-12-13

    In the computer interpretation of seismic data, the critical first step is to identify the general class of an unknown event. For example, the classification might be: teleseismic, regional, local, vehicular, or noise. Self-organizing neural networks (SONNs) can be used for classifying such events. Both Kohonen and Adaptive Resonance Theory (ART) SONNs are useful for this purpose. Given the detection of a seismic event and the corresponding signal, computation is made of: the time-frequency distribution, its binary representation, and finally a shift-invariant representation, which is the magnitude of the two-dimensional Fourier transform (2-D FFT) of the binary time-frequency distribution. This pre-processed input is fed into the SONNs. These neural networks are able to group events that look similar. The ART SONN has an advantage in classifying the event because the types of cluster groups do not need to be pre-defined. The results from the SONNs together with an expert seismologist's classification are then used to derive event classification probabilities. 21 figures.

  15. Isochannels and blocking modes of voltage-dependent sodium channels.

    PubMed

    Moczydlowski, E; Uehara, A; Guo, X; Heiny, J

    1986-01-01

    Our results support the existence of three different Na-channel subtypes or isochannels. These isochannels can be readily distinguished as the predominant Na-channel types in mammalian brain, skeletal muscle, and cardiac muscle. The sensitivity to mu-conotoxin GIIIA and tetrodotoxin is sufficient to classify these channels. The skeletal muscle channel is very sensitive to both tetrodotoxin and mu-conotoxin, the brain channel is sensitive to tetrodotoxin but insensitive to mu-conotoxin, and the heart and denervated muscle channels are insensitive to both toxins. In addition to block at the external receptor site for guanidinium toxins, several other blocking modes can be generalized for batrachotoxin-activated Na channels. One mode is peculiar to certain hydrophobic molecules so far represented by our studies of benzocaine and procaine. These molecules induce discrete blocking events with dwell times that apparently increase with anesthetic concentration and a blocking frequency that increases with negative voltage. This mode is quite distinct from the fast internal block by charged organic molecules that increases with positive voltage. These results imply that it is not possible to ascribe the diverse effects of local anesthetics to a single site in the interior channel mouth, as previously proposed by Hille. Our observations thus support the conclusions of other workers who used mixtures of two local anesthetics to show that the dose-response behavior does not fit single-site behavior, but requires at least two distinct sites. Two additional blocking modes can be distinguished for the interactions of cations at the internal and external mouths of the channel. Organic molecules can apparently enter the electric field from the internal but not the external side of the channel. This result suggests a wide internal entry way to the field and an external constriction that prevents the entry of molecules with a single methyl group but permits entry of divalent

  16. Roughness characteristics of natural channels

    USGS Publications Warehouse

    Barnes, Harry Hawthorne

    1967-01-01

    Color photographs and descriptive data are presented for 50 stream channels for which roughness coefficients have been determined. All hydraulic computations involving flow in open channels require an evaluation of the roughness characteristics of the channel. In the absence of a satisfactory quantitative procedure this evaluation remains chiefly an art. The ability to evaluate roughness coefficients must be developed through experience. One means of gaining this experience is by examining and becoming acquainted with the appearance of some typical channels whose roughness coefficients are known. The photographs and data contained in this report represent a wide range of channel conditions. Familiarity with the appearance, geometry, and roughness characteristics of these channels will improve the engineer's ability to select roughness coefficients for other channels .

  17. Chloride channels as drug targets

    PubMed Central

    Verkman, Alan S.; Galietta, Luis J. V.

    2013-01-01

    Chloride channels represent a relatively under-explored target class for drug discovery as elucidation of their identity and physiological roles has lagged behind that of many other drug targets. Chloride channels are involved in a wide range of biological functions, including epithelial fluid secretion, cell-volume regulation, neuroexcitation, smooth-muscle contraction and acidification of intracellular organelles. Mutations in several chloride channels cause human diseases, including cystic fibrosis, macular degeneration, myotonia, kidney stones, renal salt wasting and hyperekplexia. Chloride-channel modulators have potential applications in the treatment of some of these disorders, as well as in secretory diarrhoeas, polycystic kidney disease, osteoporosis and hypertension. Modulators of GABAA (γ-aminobutyric acid A) receptor chloride channels are in clinical use and several small-molecule chloride-channel modulators are in preclinical development and clinical trials. Here, we discuss the broad opportunities that remain in chloride-channel-based drug discovery. PMID:19153558

  18. Interaction of Two Filament Channels of Different Chiralities

    NASA Astrophysics Data System (ADS)

    Joshi, Navin Chandra; Filippov, Boris; Schmieder, Brigitte; Magara, Tetsuya; moon, Young-Jae; Uddin, Wahab

    2016-07-01

    We present observations of the interactions between the two filament channels of different chiralities and associated dynamics that occurred during 2014 April 18-20. While two flux ropes of different helicity with parallel axial magnetic fields can only undergo a bounce interaction when they are brought together, the observations at first glance show that the heated plasma is moving from one filament channel to the other. The SDO/AIA 171 Å observations and the potential-field source-surface magnetic field extrapolation reveal the presence of a fan-spine magnetic configuration over the filament channels with a null point located above them. Three different events of filament activations, partial eruptions, and associated filament channel interactions have been observed. The activation initiated in one filament channel seems to propagate along the neighboring filament channel. We believe that the activation and partial eruption of the filaments brings the field lines of flux ropes containing them closer to the null point and triggers the magnetic reconnection between them and the fan-spine magnetic configuration. As a result, the hot plasma moves along the outer spine line toward the remote point. Utilizing the present observations, for the first time we have discussed how two different-chirality filament channels can interact and show interrelation.

  19. Extreme events in Uttarakhand, India

    NASA Astrophysics Data System (ADS)

    Dimri, V. P.

    2013-12-01

    Uttarakhand in NW Himalaya, India is prone to various disasters, which include earthquakes, cloud bursts, landslides, floods etc. These disasters have a cascading effect. The cloud burst results in flooding of rivers and landslides. The earthquakes shake the ground causing landslides, which sometimes block the natural path of river making artificial dams. These artificial dams can cause river flooding. The situation becomes more devastating, if heavy rainfall occurs. Such disasters are increasing in recent times. There could be several reasons for the rise in frequency of these disasters because of global and local environment changes. The global changes such as rise of global temperatures due to increase in CO2 concentration in the atmosphere can be responsible for melting of Himalayan Glaciers and changes in precipitation/ rainfall patterns etc. Anthropogenic causes such as deforestation, establishment of new townships, new hydro-power projects, mining activities etc are also making the condition more vulnerable by changing the course of river channels. A case study of such extreme event is presented. The region is affected by changes of both global and local origin, tectonically as well as climatologically.

  20. Event tunnel: exploring event-driven business processes.

    PubMed

    Suntinger, Martin; Obweger, Hannes; Schiefer, Josef; Gröller, M Eduard

    2008-01-01

    Event-based systems monitor business processes in real time. The event-tunnel visualization sees the stream of events captured from such systems as a cylindrical tunnel. The tunnel allows for back-tracing business incidents and exploring event patterns' root causes. The authors couple this visualization with tools that let users search for relevant events within a data repository.

  1. Concepts of event-by-event analysis

    SciTech Connect

    Stroebele, H.

    1995-07-15

    The particles observed in the final state of nuclear collisions can be divided into two classes: those which are susceptible to strong interactions and those which are not, like leptons and the photon. The bulk properties of the {open_quotes}matter{close_quotes} in the reaction zone may be read-off the kinematical characteristics of the particles observable in the final state. These characteristics are strongly dependent on the last interaction these particles have undergone. In a densly populated reaction zone strongly interacting particles will experience many collisions after they have been formed and before they emerge into the asymptotic final state. For the particles which are not sensitive to strong interactions their formation is also their last interaction. Thus photons and leptons probe the period during which they are produced whereas hadrons reflect the so called freeze-out processes, which occur during the late stage in the evolution of the reaction when the population density becomes small and the mean free paths long. The disadvantage of the leptons and photons is their small production cross section; they cannot be used in an analysis of the characteristics of individual collision events, because the number of particles produced per event is too small. The hadrons, on the other hand, stem from the freeze-out period. Information from earlier periods requires multiparticle observables in the most general sense. It is one of the challenges of present day high energy nuclear physics to establish and understand global observables which differentiate between mere hadronic scenarios, i.e superposition of hadronic interactions, and the formation of a partonic (short duration) steady state which can be considered a new state of matter, the Quark-Gluon Plasma.

  2. Potential Energy Calculations for Collinear Cluster Tripartition Fission Events

    NASA Astrophysics Data System (ADS)

    Unzhakova, A. V.; Pashkevich, V. V.; Pyatkov, Y. V.

    2014-09-01

    Strutinsky shell correction calculations were performed to describe the recent experimental results on collinear ternary fission. Collinear Cluster Tripartion fission events were studied experimentally in neutron induced fission of 235U, where the missing mass in the detected binary decay was suggested to characterize fission event as a collinear tripartition; and in spontaneous fission of 252Cf, where the direct detection of the three fission fragments has been used to confirm the existence of the Collinear Cluster Tripartition channel with a probability of 4.7×10-3 relative to the binary fission events.

  3. Channels and Erosion

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 20 June 2003

    The dissected and eroded channel observed in this THEMIS image taken of plains materials southwest of the volcano Elysium Mons shows typical erosional islands and depositional features. The interesting thing about this channel is that it appears to start out of nowhere. The MOLA context image shows that the channel originates from a fissure within the ground, whose origin is likely volcanic, but may also be related to volatile processes.

    Image information: VIS instrument. Latitude 19.5, Longitude 126.8 East (233.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. Permeation in potassium channels: implications for channel structure.

    PubMed

    Yellen, G

    1987-01-01

    The SR K+ channel is a single-ion channel with a tunnel that is not very selective, while the DR and CaK channels are both more selective, multi-ion channels. The permeation mechanisms of the three channels are probably most systematically distinguished by the length of their tunnels; the SR has the shortest and the DR the longest. Although different in their mechanisms of activation, the DR and CaK channels have very similar permeation characteristics, down to the details of selectivity and blockade. The longer tunnel and reduced conductance (perhaps a result of the extra tunnel length) of the DR K+ channel are the main differences. The selectivity of the rate-limiting barriers and the binding sites within the channels, however, are strikingly similar. A successful potassium channel must satisfy two criteria: It must let potassium ions through and not much else, and it must let many potassium ions through. To be selective the channel must have a narrow selectivity filter, so that an ion must shed some of its waters of hydration to pass through. Sodium ions are excluded because they are more reluctant to lose their water, and they are not adequately compensated for this loss by interaction with the selectivity filter. To carry a large current the narrow region must be short, with wide antechambers to reduce the diffusional access resistance (48). Energetically, the channel must strike a balance. There must be enough binding energy to compensate the ions for their lost hydration energy, so that the energy barrier to permeation is small. If the channel binds the ion too tightly, however, the ion will not be able to exit, and the current will be small. Some of the shared properties of different potassium channels are probably consequences of these requirements; others may be incidental to function, suggesting a common origin. Barium ions have almost exactly the same radius as potassium ions but twice the charge, so it is perhaps not surprising that barium can block

  5. Data Discovery and Access via the Heliophysics Events Knowledgebase (HEK)

    NASA Astrophysics Data System (ADS)

    Somani, A.; Hurlburt, N. E.; Schrijver, C. J.; Cheung, M.; Freeland, S.; Slater, G. L.; Seguin, R.; Timmons, R.; Green, S.; Chang, L.; Kobashi, A.; Jaffey, A.

    2011-12-01

    The HEK is a integrated system which helps direct scientists to solar events and data from a variety of providers. The system is fully operational and adoption of HEK has been growing since the launch of NASA's SDO mission. In this presentation we describe the different components that comprise HEK. The Heliophysics Events Registry (HER) and Heliophysics Coverage Registry (HCR) form the two major databases behind the system. The HCR allows the user to search on coverage event metadata for a variety of instruments. The HER allows the user to search on annotated event metadata for a variety of instruments. Both the HCR and HER are accessible via a web API which can return search results in machine readable formats (e.g. XML and JSON). A variety of SolarSoft services are also provided to allow users to search the HEK as well as obtain and manipulate data. Other components include - the Event Detection System (EDS) continually runs feature finding algorithms on SDO data to populate the HER with relevant events, - A web form for users to request SDO data cutouts for multiple AIA channels as well as HMI line-of-sight magnetograms, - iSolSearch, which allows a user to browse events in the HER and search for specific events over a specific time interval, all within a graphical web page, - Panorama, which is the software tool used for rapid visualization of large volumes of solar image data in multiple channels/wavelengths. The user can also easily create WYSIWYG movies and launch the Annotator tool to describe events and features. - EVACS, which provides a JOGL powered client for the HER and HCR. EVACS displays the searched for events on a full disk magnetogram of the sun while displaying more detailed information for events.

  6. Dynamics of Transmissionlosses In Arid Stream Channels

    NASA Astrophysics Data System (ADS)

    Lange, J.; Mostert, A.; Wessels, C.

    In dry areas streamflow losses of ephemeral rivers are important contributions to groundwater recharge. The importance of these losses increases with aridity U in hy- perarid areas they often form the only freshwater source for aquifers sustaining water supply and life of the local population. However, just in these areas little is known about processes involved, as gauging and monitoring of surface water flow is made difficult due to the low population, remoteness of hydrological stations and short du- rations of floods. Using a physically based flow routing scheme on an event basis this study wants to contribute to the knowledge of the nature and dynamics of chan- nel transmission losses in large arid stream channels. In the 15500 km2 Kuiseb River catchment, western Namibia, annual rainfall decreases from 275 in the east to just about 0 in the west. With a distinct drop in altitude the downstream part of the basin makes up one of the driest regions in the world. A 200 km channel in the lower reaches of the Kuiseb River serves as an ideal field laboratory to simulate the transmission of flash floods because of the following reasons: i) Almost 20 years of flow records up and downstream ii) Negligible lateral inflow along the reach due to hyperarid condi- tions iii) Comparatively frequent flows due to the semiarid headwaters Hydrographs of two upstream stations serve as input for the routing scheme in a 5 min time step. Geometric information required is taken from aerial photography, topographical maps and surveyed cross sections. At the downstream end of the reach 20 simulated hy- drographs are compared with gauged events. Without calibration the routing scheme nicely documents that small floods (< 60-80 m3/s) are not significantly reduced, if they travel on a wet channel, while under the same circumstances large floods (> 120- 140 m3/s) loose up to 50% of their runoff peak. This difference is important for the assessment of groundwater recharge and may be

  7. A Micromechanical RF Channelizer

    NASA Astrophysics Data System (ADS)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  8. RETRIEVAL EVENTS EVALUATION

    SciTech Connect

    T. Wilson

    1999-11-12

    The purpose of this analysis is to evaluate impacts to the retrieval concept presented in the Design Analysis ''Retrieval Equipment and Strategy'' (Reference 6), from abnormal events based on Design Basis Events (DBE) and Beyond Design Basis Events (BDBE) as defined in two recent analyses: (1) DBE/Scenario Analysis for Preclosure Repository Subsurface Facilities (Reference 4); and (2) Preliminary Preclosure Design Basis Event Calculations for the Monitored Geologic Repository (Reference 5) The objective of this task is to determine what impacts the DBEs and BDBEs have on the equipment developed for retrieval. The analysis lists potential impacts and recommends changes to be analyzed in subsequent design analyses for developed equipment, or recommend where additional equipment may be needed, to allow retrieval to be performed in all DBE or BDBE situations. This analysis supports License Application design and therefore complies with the requirements of Systems Description Document input criteria comparison as presented in Section 7, Conclusions. In addition, the analysis discusses the impacts associated with not using concrete inverts in the emplacement drifts. The ''Retrieval Equipment and Strategy'' analysis was based on a concrete invert configuration in the emplacement drift. The scope of the analysis, as presented in ''Development Plan for Retrieval Events Evaluation'' (Reference 3) includes evaluation and criteria of the following: Impacts to retrieval from the emplacement drift based on DBE/BDBEs, and changes to the invert configuration for the preclosure period. Impacts to retrieval from the main drifts based on DBE/BDBEs for the preclosure period.

  9. Solar extreme events

    NASA Astrophysics Data System (ADS)

    Hudson, Hugh S.

    2015-08-01

    Solar flares and CMEs have a broad range of magnitudes. This review discusses the possibility of “extreme events,” defined as those with magnitudes greater than have been seen in the existing historical record. For most quantitative measures, this direct information does not extend more than a century and a half into the recent past. The magnitude distributions (occurrence frequencies) of solar events (flares/CMEs) typically decrease with the parameter measured or inferred (peak flux, mass, energy etc. Flare radiation fluxes tend to follow a power law slightly flatter than S-2, where S represents a peak flux; solar particle events (SPEs) follow a still flatter power law up to a limiting magnitude, and then appear to roll over to a steeper distribution, which may take an exponential form or follow a broken power law. This inference comes from the terrestrial 14C record and from the depth dependence of various radioisotope proxies in the lunar regolith and in meteorites. Recently major new observational results have impacted our use of the relatively limited historical record in new ways: the detection of actual events in the 14C tree-ring records, and the systematic observations of flares and “superflares” by the Kepler spacecraft. I discuss how these new findings may affect our understanding of the distribution function expected for extreme solar events.

  10. Channel Wall Landslides

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The multiple landslides in this VIS image occur along a steep channel wall. Note the large impact crater in the context image. The formation of the crater may have initially weakened that area of the surface prior to channel formation.

    Image information: VIS instrument. Latitude -2.7, Longitude 324.8 East (35.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  11. Minio Vallis Channel

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This VIS image is of the southern reach of Minio Vallis, a small fluvial channel located near the larger Mangala Vallis. Both channels are in the Tharsis region, in the area west of Arsia Mons and southeast of Medusae Fossae.

    Image information: VIS instrument. Latitude -8.2, Longitude 208.1 East (151.9 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Cholesterol binding to ion channels

    PubMed Central

    Levitan, Irena; Singh, Dev K.; Rosenhouse-Dantsker, Avia

    2014-01-01

    Numerous studies demonstrated that membrane cholesterol is a major regulator of ion channel function. The goal of this review is to discuss significant advances that have been recently achieved in elucidating the mechanisms responsible for cholesterol regulation of ion channels. The first major insight that comes from growing number of studies that based on the sterol specificity of cholesterol effects, show that several types of ion channels (nAChR, Kir, BK, TRPV) are regulated by specific sterol-protein interactions. This conclusion is supported by demonstrating direct saturable binding of cholesterol to a bacterial Kir channel. The second major advance in the field is the identification of putative cholesterol binding sites in several types of ion channels. These include sites at locations associated with the well-known cholesterol binding motif CRAC and its reversed form CARC in nAChR, BK, and TRPV, as well as novel cholesterol binding regions in Kir channels. Notably, in the majority of these channels, cholesterol is suggested to interact mainly with hydrophobic residues in non-annular regions of the channels being embedded in between transmembrane protein helices. We also discuss how identification of putative cholesterol binding sites is an essential step to understand the mechanistic basis of cholesterol-induced channel regulation. Clearly, however, these are only the first few steps in obtaining a general understanding of cholesterol-ion channels interactions and their roles in cellular and organ functions. PMID:24616704

  13. Field observations of a debris flow event in the Dolomites

    NASA Astrophysics Data System (ADS)

    Berti, Matteo; Genevois, Rinaldo; Simoni, Alessandro; Tecca, Pia Rosella

    1999-09-01

    A debris flow event occurred in June 1997 in the Dolomites (Eastern Alps, Italy). The phenomenon was directly observed in the field and recorded by a video camera near its initiation area. The debris flow originated shortly after an intense rainstorm (25 mm in 30 min) whose runoff mobilised the loose coarse debris that filled the bottom of the channel in its upper part. The analysis of the steep headwater basin indicates a very short concentration time (9-14 min) that fits the quick hydrological response observed in the field. The debris flow mobilisation was not contemporaneous with the arrival of the peak water discharge in the initiation area probably due to the time required for the saturation of the highly conductive channel-bed material. Channel cross-section measurements taken along the flow channel indicate debris flow peak velocity and discharge ranging from 3.1 to 9.0 m/s and from 23 to 71 m 3/s, respectively. Samples collected immediately after deposition were used to determine the water content and bulk density of the material. Channel scouring, fines enrichment and transported volume increase testify erosion and entrainment of material along the flow channel. Field estimates of the rheological properties based on open channel flow of Bingham fluid indicate a yield strength of 5000±400 Pa and relatively low viscosity (60-326 Pa s), probably due to a high percentage of fines (approx. 30%).

  14. Pharmacogenomics of suicidal events

    PubMed Central

    Brent, David; Melhem, Nadine; Turecki, Gustavo

    2010-01-01

    Pharmacogenomic studies of antidepressant treatment-emergent suicidal events in depressed patients report associations with polymorphisms in genes involved in transcription (CREB1), neuroprotection (BDNF and NTRK2), glutamatergic and noradrenergic neurotransmission (GRIA3, GRIK2 and ADRA2A), the stress and inflammatory responses (FKBP5 and IL28RA), and the synthesis of glycoproteins (PAPLN). Nearly all of the reported events in these studies were modest one-time increases in suicidal ideation. In 3231 unique subjects across six studies, 424 (13.1%) patients showed increases in suicidal ideation, eight (0.25%) attempted suicide and four (0.12%) completed suicide. Systems related to most of these genes have also been implicated in studies of suicidal behavior irrespective of treatment. Future pharmacogenomic studies should target events that are clinically significant, related clinical phenotypes of response and medication side effects, and biological pathways that are involved in these outcomes in order to improve treatment approaches. PMID:20504254

  15. Detection of anomalous events

    DOEpatents

    Ferragut, Erik M.; Laska, Jason A.; Bridges, Robert A.

    2016-06-07

    A system is described for receiving a stream of events and scoring the events based on anomalousness and maliciousness (or other classification). The system can include a plurality of anomaly detectors that together implement an algorithm to identify low-probability events and detect atypical traffic patterns. The anomaly detector provides for comparability of disparate sources of data (e.g., network flow data and firewall logs.) Additionally, the anomaly detector allows for regulatability, meaning that the algorithm can be user configurable to adjust a number of false alerts. The anomaly detector can be used for a variety of probability density functions, including normal Gaussian distributions, irregular distributions, as well as functions associated with continuous or discrete variables.

  16. Sarcolemmal KATP channel modulators and cardiac arrhythmias.

    PubMed

    Baczkó, I; Husti, Z; Lang, V; Leprán, I; Light, P E

    2011-01-01

    Cardiac atrial and ventricular arrhythmias are major causes of mortality and morbidity. Ischemic heart disease is the most common cause underlying 1) the development of ventricular fibrillation that results in sudden cardiac death and 2) atrial fibrillation that can lead to heart failure and stroke. Current pharmacological agents for the treatment of ventricular and atrial arrhythmias exhibit limited effectiveness and many of these agents can cause serious adverse effects - including the provocation of lethal ventricular arrhythmias. Sarcolemmal ATP-sensitive potassium channels (sarcK(ATP)) couple cellular metabolism to membrane excitability in a wide range of tissues. In the heart, sarcK(ATP) are activated during metabolic stress including myocardial ischemia, and both the opening of sarcK(ATP) and mitochondrial K(ATP) channels protect the ischemic myocardium via distinct mechanisms. Myocardial ischemia leads to a series of events that promote the generation of arrhythmia substrate eventually resulting in the development of life-threatening arrhythmias. In this review, the possible mechanisms of the anti- and proarrhythmic effects of sarcK(ATP) modulation as well as the influence of pharmacological K(ATP) modulators are discussed. It is concluded that in spite of the significant advances made in this field, the possible cardiovascular therapeutic utility of current sarcK(ATP) channel modulators is still hampered by the lack of chamber-specific selectivity. However, recent insights into the chamber-specific differences in the molecular composition of sarcKATP in addition to already existing cardioselective sarcK(ATP) channel modulators with sarcK(ATP) isoform selectivity holds the promise for the future development of pharmacological strategies specific for a variety of atrial and ventricular arrhythmias.

  17. Ion channel therapeutics for pain

    PubMed Central

    Skerratt, Sarah E; West, Christopher W

    2015-01-01

    Pain is a complex disease which can progress into a debilitating condition. The effective treatment of pain remains a challenge as current therapies often lack the desired level of efficacy or tolerability. One therapeutic avenue, the modulation of ion channel signaling by small molecules, has shown the ability to treat pain. However, of the 215 ion channels that exist in the human genome, with 85 ion channels having a strong literature link to pain, only a small number of these channels have been successfully drugged for pain. The focus of future research will be to fully explore the possibilities surrounding these unexplored ion channels. Toward this end, a greater understanding of ion channel modulation will be the greatest tool we have in developing the next generation of drugs for the treatment of pain. PMID:26218246

  18. Phosphoinositide regulation of TRP channels

    PubMed Central

    Rohacs, Tibor

    2015-01-01

    Transient Receptor Potential (TRP) channels are activated by stimuli as diverse as heat, cold, noxious chemicals, mechanical forces, hormones, neurotransmitters, spices, and voltage. Besides their presumably similar general architecture, probably the only common factor regulating them is phosphoinositides. The regulation of TRP channels by phosphoinositides is complex. There is a large number of TRP channels where phosphatidylinositol 4,5 bisphosphate [PI(4,5)P2 or PIP2], acts as a positive cofactor, similarly to many other ion channels. In several cases however, PI(4,5)P2 inhibits TRP channel activity, sometimes even concurrently with the activating effect. This review will provide a comprehensive overview of the literature on regulation of TRP channels by membrane phosphoinositides. PMID:24961984

  19. Molecular Mechanism of TRP Channels

    PubMed Central

    Zheng, Jie

    2013-01-01

    Transient receptor potential (TRP) channels are cellular sensors for a wide spectrum of physical and chemical stimuli. They are involved in the formation of sight, hearing, touch, smell, taste, temperature, and pain sensation. TRP channels also play fundamental roles in cell signaling and allow the host cell to respond to benign or harmful environmental changes. As TRP channel activation is controlled by very diverse processes and, in many cases, exhibits complex polymodal properties, understanding how each TRP channel responds to its unique forms of activation energy is both crucial and challenging. The past two decades witnessed significant advances in understanding the molecular mechanisms that underlie TRP channels activation. This review focuses on our current understanding of the molecular determinants for TRP channel activation. PMID:23720286

  20. Peptide models for membrane channels.

    PubMed Central

    Marsh, D

    1996-01-01

    Peptides may be synthesized with sequences corresponding to putative transmembrane domains and/or pore-lining regions that are deduced from the primary structures of ion channel proteins. These can then be incorporated into lipid bilayer membranes for structural and functional studies. In addition to the ability to invoke ion channel activity, critical issues are the secondary structures adopted and the mode of assembly of these short transmembrane peptides in the reconstituted systems. The present review concentrates on results obtained with peptides from ligand-gated and voltage-gated ion channels, as well as proton-conducting channels. These are considered within the context of current molecular models and the limited data available on the structure of native ion channels and natural channel-forming peptides. PMID:8615800

  1. The Channel Tunnel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Channel Tunnel is a 50.5 km-long rail tunnel beneath the English Channel at the Straits of Dover. It connects Dover, Kent in England with Calais, northern France. The undersea section of the tunnel is unsurpassed in length in the world. A proposal for a Channel tunnel was first put forward by a French engineer in 1802. In 1881, a first attempt was made at boring a tunnel from the English side; the work was halted after 800 m. Again in 1922, English workers started boring a tunnel, and advanced 120 m before it too was halted for political reasons. The most recent attempt was begun in 1987, and the tunnel was officially opened in 1994. At completion it was estimated that the project cost around $18 billion. It has been operating at a significant loss since its opening, despite trips by over 7 million passengers per year on the Eurostar train, and over 3 million vehicles per year.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring

  2. Single-channel kinetics of BK (Slo1) channels

    PubMed Central

    Geng, Yanyan; Magleby, Karl L.

    2014-01-01

    Single-channel kinetics has proven a powerful tool to reveal information about the gating mechanisms that control the opening and closing of ion channels. This introductory review focuses on the gating of large conductance Ca2+- and voltage-activated K+ (BK or Slo1) channels at the single-channel level. It starts with single-channel current records and progresses to presentation and analysis of single-channel data and the development of gating mechanisms in terms of discrete state Markov (DSM) models. The DSM models are formulated in terms of the tetrameric modular structure of BK channels, consisting of a central transmembrane pore-gate domain (PGD) attached to four surrounding transmembrane voltage sensing domains (VSD) and a large intracellular cytosolic domain (CTD), also referred to as the gating ring. The modular structure and data analysis shows that the Ca2+ and voltage dependent gating considered separately can each be approximated by 10-state two-tiered models with five closed states on the upper tier and five open states on the lower tier. The modular structure and joint Ca2+ and voltage dependent gating are consistent with a 50 state two-tiered model with 25 closed states on the upper tier and 25 open states on the lower tier. Adding an additional tier of brief closed (flicker states) to the 10-state or 50-state models improved the description of the gating. For fixed experimental conditions a channel would gate in only a subset of the potential number of states. The detected number of states and the correlations between adjacent interval durations are consistent with the tiered models. The examined models can account for the single-channel kinetics and the bursting behavior of gating. Ca2+ and voltage activate BK channels by predominantly increasing the effective opening rate of the channel with a smaller decrease in the effective closing rate. Ca2+ and depolarization thus activate by mainly destabilizing the closed states. PMID:25653620

  3. Teaching with Current Events

    ERIC Educational Resources Information Center

    Peralta, Andrew

    2005-01-01

    This article describes how a teacher changed all his plans to teach the hurricane. When the Hurricane Katrina hit the Gulf Coast, kids become naturally curious and seek answers in an event this big. The author suggests the use of tragedies to help them grow as students and as citizens.

  4. Language As Social Event.

    ERIC Educational Resources Information Center

    Harste, Jerome C.

    A taxonomy developed for the study of the growth and development of written language from the perspective of social event was tested with a group of 68 children, aged three to six years. The subjects were presented with a wide variety of environmental print messages (road signs, toys, fast food signs, and household products) and were questioned…

  5. SIMULATING SUB-DECADAL CHANNEL MORPHOLOGIC CHANGE IN EPHEMERAL STREAM NETWORKS

    EPA Science Inventory

    A distributed watershed model was modified to simulate cumulative channel morphologic
    change from multiple runoff events in ephemeral stream networks. The model incorporates the general design of the event-based Kinematic Runoff and" Erosion Model (KINEROS), which describes t...

  6. Quaternary geology of the Channeled Scabland and adjacent areas

    NASA Technical Reports Server (NTRS)

    Baker, V. R.

    1978-01-01

    The quaternary history of the channeled scabland is characterized by discrete episodes of catastrophic flooding and prolonged periods of loess accumulation and soil formation. The loess sequence was correlated with Richmond's Rocky Mountain glacial chronology. At least five major catastrophic flood events occurred in the general vicinity of the channeled scabland. The earliest episode occurred prior to the extensive deposition of the Palouse formation. The last major episode of flooding occurred between about 18,000 and 13,000 years ago. It probably consisted of two outbursts from glacial Lake Missoula.

  7. Detailed Design of the Heliophysics Event Knowledgebase (HEK)

    NASA Astrophysics Data System (ADS)

    Somani, Ankur; Seguin, R.; Timmons, R.; Freeland, S.; Hurlburt, N.; Kobashi, A.; Jaffey, A.

    2010-05-01

    We present the Heliophysics Event Registry (HER) and the Heliophysics Coverage Registry (HCR), which serve as two components of the Heliophysics Event Knowledgebase (HEK). Using standardized XML formats built upon the IVOA VOEvent specification, events can be ingested, stored, and later searched upon. Various web services and SolarSoft routines are available to aid in these functions. One source of events for the HEK is an automated Event Detection System (EDS) that continuously runs feature finding modules on SDO data. Modules are primarily supplied by the Smithsonian Astrophysical Observatory-led Feature Finding Team. The distributed system will keep up with SDO's data rate and issue space weather alerts in near-real time. Some modules will be run on all data while others are run in response to certain solar phenomena found by other modules in the system. Panorama is a software tool used for rapid visualization of large volumes of solar image data in multiple channels/wavelengths. With the EVACS front-end GUI tool, Panorama allows the user to, in real-time, change channel pixel scaling, weights, alignment, blending and colorization of the data. The user can also easily create WYSIWYG movies and launch the Annotator tool to describe events and features the user observes in the data. Panorama can also be used to drive clustered HiperSpace walls using the CGLX toolkit. The Event Viewer and Control Software (EVACS) provides a GUI that the user can search both the HER and HCR with. By specifying a start and end time and selecting the types of events and instruments that are of interest, EVACS will display the events on a full disk image of the sun while displaying more detailed information for the events. As mentioned, the user can also launch Panorama via EVACS.

  8. Ultrasound modulates ion channel currents.

    PubMed

    Kubanek, Jan; Shi, Jingyi; Marsh, Jon; Chen, Di; Deng, Cheri; Cui, Jianmin

    2016-01-01

    Transcranial focused ultrasound (US) has been demonstrated to stimulate neurons in animals and humans, but the mechanism of this effect is unknown. It has been hypothesized that US, a mechanical stimulus, may mediate cellular discharge by activating mechanosensitive ion channels embedded within cellular membranes. To test this hypothesis, we expressed potassium and sodium mechanosensitive ion channels (channels of the two-pore-domain potassium family (K2P) including TREK-1, TREK-2, TRAAK; NaV1.5) in the Xenopus oocyte system. Focused US (10 MHz, 0.3-4.9 W/cm(2)) modulated the currents flowing through the ion channels on average by up to 23%, depending on channel and stimulus intensity. The effects were reversible upon repeated stimulation and were abolished when a channel blocker (ranolazine to block NaV1.5, BaCl2 to block K2P channels) was applied to the solution. These data reveal at the single cell level that focused US modulates the activity of specific ion channels to mediate transmembrane currents. These findings open doors to investigations of the effects of  US on ion channels expressed in neurons, retinal cells, or cardiac cells, which may lead to important medical applications. The findings may also pave the way to the development of sonogenetics: a non-invasive, US-based analogue of optogenetics. PMID:27112990

  9. Flag flapping in a channel

    NASA Astrophysics Data System (ADS)

    Alben, Silas; Shoele, Kourosh; Mittal, Rajat; Jha, Sourabh; Glezer, Ari

    2015-11-01

    We study the flapping of a flag in an inviscid channel flow. We focus especially on how quantities vary with channel spacing. As the channel walls move inwards towards the flag, heavier flags become more unstable, while light flags' stability is less affected. We use a vortex sheet model to compute large-amplitude flapping, and find that the flag undergoes a series of jumps to higher flapping modes as the channel walls are moved towards the flag. Meanwhile, the drag on the flag and the energy lost to the wake first rise as the walls become closer, then drop sharply as the flag moves to a higher flapping mode.

  10. Designed membrane channels and pores.

    PubMed

    Bayley, H

    1999-02-01

    Advances in the synthesis and assembly of designed membrane channels and pores include addressable template-assisted synthetic protein (TASP) syntheses of helix bundles, the production of a new class of nanotubes and the ability to purify hetero-oligomeric pores. Channels and pores with altered functional properties and with built-in triggers and switches have been prepared. Progress in applications has been greatest in sensor technology, where sensor elements based on ligand activation, channel selectivity and channel block have been made. Structural information about natural membrane proteins is emerging to inspire new designs.

  11. Ultrasound modulates ion channel currents

    PubMed Central

    Kubanek, Jan; Shi, Jingyi; Marsh, Jon; Chen, Di; Deng, Cheri; Cui, Jianmin

    2016-01-01

    Transcranial focused ultrasound (US) has been demonstrated to stimulate neurons in animals and humans, but the mechanism of this effect is unknown. It has been hypothesized that US, a mechanical stimulus, may mediate cellular discharge by activating mechanosensitive ion channels embedded within cellular membranes. To test this hypothesis, we expressed potassium and sodium mechanosensitive ion channels (channels of the two-pore-domain potassium family (K2P) including TREK-1, TREK-2, TRAAK; NaV1.5) in the Xenopus oocyte system. Focused US (10 MHz, 0.3–4.9 W/cm2) modulated the currents flowing through the ion channels on average by up to 23%, depending on channel and stimulus intensity. The effects were reversible upon repeated stimulation and were abolished when a channel blocker (ranolazine to block NaV1.5, BaCl2 to block K2P channels) was applied to the solution. These data reveal at the single cell level that focused US modulates the activity of specific ion channels to mediate transmembrane currents. These findings open doors to investigations of the effects of  US on ion channels expressed in neurons, retinal cells, or cardiac cells, which may lead to important medical applications. The findings may also pave the way to the development of sonogenetics: a non-invasive, US-based analogue of optogenetics. PMID:27112990

  12. Demystifying Mechanosensitive Piezo Ion Channels.

    PubMed

    Xu, X Z Shawn

    2016-06-01

    Mechanosensitive channels mediate touch, hearing, proprioception, and blood pressure regulation. Piezo proteins, including Piezo1 and Piezo2, represent a new class of mechanosensitive channels that have been reported to play key roles in most, if not all, of these modalities. The structural architecture and molecular mechanisms by which Piezos act as mechanosensitive channels, however, remain mysterious. Two new studies have now provided critical insights into the atomic structure and molecular basis of the ion permeation and mechano-gating properties of the Piezo1 channel.

  13. The Discovery Channel Telescope

    NASA Astrophysics Data System (ADS)

    Millis, R. L.; Dunham, E. W.; Sebring, T. A.; Smith, B. W.; de Kock, M.; Wiecha, O.

    2004-11-01

    The Discovery Channel Telescope (DCT) is a 4.2-m telescope to be built at a new site near Happy Jack, Arizona. The DCT features a large prime focus mosaic CCD camera with a 2-degree-diameter field of view especially designed for surveys of KBOs, Centaurs, NEAs and other moving or time-variable targets. The telescope can be switched quickly to a Ritchey-Chretien configuration for optical/IR spectroscopy or near-IR imaging. This flexibility allows timely follow-up physical studies of high priority objects discovered in survey mode. The ULE (ultra-low-expansion) meniscus primary and secondary mirror blanks for the telescope are currently in fabrication by Corning Glass. Goodrich Aerospace, Vertex RSI, M3 Engineering and Technology Corp., and e2v Technologies have recently completed in-depth conceptual design studies of the optics, mount, enclosure, and mosaic focal plane, respectively. The results of these studies were subjected to a formal design review in July, 2004. Site testing at the 7760-ft altitude Happy Jack site began in 2001. Differential image motion observations from 117 nights since January 1, 2003 gave median seeing of 0.84 arcsec FWHM, and the average of the first quartile was 0.62 arcsec. The National Environmental Policy Act (NEPA) process for securing long-term access to this site on the Coconino National Forest is nearing completion and ground breaking is expected in the spring of 2005. The Discovery Channel Telescope is a project of the Lowell Observatory with major financial support from Discovery Communications, Inc. (DCI). DCI plans ongoing television programming featuring the construction of the telescope and the research ultimately undertaken with the DCT. An additional partner can be accommodated in the project. Interested parties should contact the lead author.

  14. Characteristics of solar proton events associated with ground level enhancements

    NASA Astrophysics Data System (ADS)

    Oh, S. Y.; Yi, Y.; Bieber, J. W.; Evenson, P.; Kim, Y. K.

    2010-10-01

    In certain explosive events, the Sun emits large numbers of protons with energy up to tens of GeV. Particle acceleration processes on the Sun can be understood through the observation of such energetic particles. According to the definition of NOAA Space Environment Services Center, a solar proton event (SPE) is defined as an event with a peak intensity of >10 pfu (particle flux unit; 1 particle cm-2 sr-1 s-1) for >10 MeV protons. Major SPEs are not always associated with ground level enhancements (GLEs), whereas relatively minor SPEs are sometimes associated with GLEs. We examined the peak intensities of 85 SPEs after 1986 using the intensity of proton differential energy channels (P3-P10) from GOES. We identified 31 SPEs associated with GLEs having well-defined profiles with a large increase and clear peak for each proton channel. They have larger peak intensity and fluence and shorter delay time between onset and peak than SPEs without GLEs. Fluences and peak intensities of SPEs have a good correlation with percent increases of GLEs, with the best correlation coefficients obtained for the peak intensities and fluences of channels P8, P9, and P10. For these energy channels (spanning 350-700 MeV), we find that there are threshold values for GOES fluence and peak intensity such that most SPEs above the threshold are associated with GLEs, whereas almost none below the thresholds are.

  15. Single channel studies of the phosphorylation of K+ channels in the squid giant axon. I. Steady-state conditions

    PubMed Central

    1991-01-01

    Phosphorylation of the delayed rectifier channel of squid potentiates the macroscopic K+ current and slows its activation kinetics. We have studied this phenomenon at the single channel level using the cut-open axon technique under steady-state conditions. In 10 mM external K+/310 mM internal K+ there are predominantly two types of channels present, a 20-pS and a 40-pS channel. In steady state at depolarized potentials, the 40-pS channel was most active, whereas the 20-pS channel tended to disappear due to a slow inactivation process. Two methods were developed to shift the population of channels toward a dephosphorylated state. One method consisted of predialyzing a whole axon with solutions containing no ATP, while recording the currents under axial-wire voltage clamp. A piece of axon was then removed and cut open, and single channel currents were recorded from the cut-open axon. A second method was based on the difference in diffusion coefficients for ATP and proteins such as the endogenous phosphatase. The axon was cut open in a solution that did not contain Ca2+ or Cl- in order to maintain the axoplasm structurally intact and permit endogenous phosphatase to act on the membrane while ATP diffused away, before removing the axoplasm and forming a membrane patch. When dephosphorylating conditions were used, the steady-state open probability of the 40-pS channel at 42 mV was very low (less than 0.0002), and the channel openings appeared as a series of infrequent, short-duration events. The channel activity was increased up to 150-fold by photoreleasing caged ATP inside the patch pipette in the presence of the catalytic subunit of protein kinase A. The sharp increase in open probability could be accounted for by a decrease of the slow component of the closed time distribution from 23 s to 170 ms with little change in the distribution of open times (1-2 ms) and no change in the single channel current amplitude. In voltage- jump experiments the contribution of the 40

  16. EPR Studies of Gating Mechanisms in Ion Channels

    PubMed Central

    Chakrapani, Sudha

    2015-01-01

    Ion channels open and close in response to diverse stimuli, and the molecular events underlying these processes are extensively modulated by ligands of both endogenous and exogenous origin. In the past decade, high-resolution structures of several channel types have been solved, providing unprecedented details of the molecular architecture of these membrane proteins. Intrinsic conformational flexibility of ion channels critically governs their functions. However, the dynamics underlying gating mechanisms and modulations are obscured in the information from crystal structures. While nuclear magnetic resonance spectroscopic methods allow direct measurements of protein dynamics, they are limited by the large size of these membrane protein assemblies in detergent micelles or lipid membranes. Electron paramagnetic resonance (EPR) spectroscopy has emerged as a key biophysical tool to characterize structural dynamics of ion channels and to determine stimulus-driven conformational transition between functional states in a physiological environment. This review will provide an overview of the recent advances in the field of voltage- and ligand-gated channels and highlight some of the challenges and controversies surrounding the structural information available. It will discuss general methods used in site-directed spin labeling and EPR spectroscopy and illustrate how findings from these studies have narrowed the gap between high-resolution structures and gating mechanisms in membranes, and have thereby helped reconcile seemingly disparate models of ion channel function. PMID:25950970

  17. Interaction of the BKCa channel gating ring with dendrotoxins

    PubMed Central

    Takacs, Zoltan; Imredy, John P; Bingham, Jon-Paul; Zhorov, Boris S; Moczydlowski, Edward G

    2014-01-01

    Two classes of small homologous basic proteins, mamba snake dendrotoxins (DTX) and bovine pancreatic trypsin inhibitor (BPTI), block the large conductance Ca2+-activated K+ channel (BKCa, KCa1.1) by production of discrete subconductance events when added to the intracellular side of the membrane. This toxin-channel interaction is unlikely to be pharmacologically relevant to the action of mamba venom, but as a fortuitous ligand-protein interaction, it has certain biophysical implications for the mechanism of BKCa channel gating. In this work we examined the subconductance behavior of 9 natural dendrotoxin homologs and 6 charge neutralization mutants of δ-dendrotoxin in the context of current structural information on the intracellular gating ring domain of the BKCa channel. Calculation of an electrostatic surface map of the BKCa gating ring based on the Poisson-Boltzmann equation reveals a predominantly electronegative surface due to an abundance of solvent-accessible side chains of negatively charged amino acids. Available structure-activity information suggests that cationic DTX/BPTI molecules bind by electrostatic attraction to site(s) on the gating ring located in or near the cytoplasmic side portals where the inactivation ball peptide of the β2 subunit enters to block the channel. Such an interaction may decrease the apparent unitary conductance by altering the dynamic balance of open versus closed states of BKCa channel activation gating. PMID:25483585

  18. TRANSIENT BRIGHTENINGS ASSOCIATED WITH FLUX CANCELLATION ALONG A FILAMENT CHANNEL

    SciTech Connect

    Wang, Y.-M.; Muglach, K. E-mail: karin.muglach@nasa.gov

    2013-02-15

    Filament channels coincide with large-scale polarity inversion lines of the photospheric magnetic field, where flux cancellation continually takes place. High-cadence Solar Dynamics Observatory (SDO) images recorded in He II 30.4 nm and Fe IX 17.1 nm during 2010 August 22 reveal numerous transient brightenings occurring along the edge of a filament channel within a decaying active region, where SDO line-of-sight magnetograms show strong opposite-polarity flux in close contact. The brightenings are elongated along the direction of the filament channel, with linear extents of several arcseconds, and typically last a few minutes; they sometimes have the form of multiple two-sided ejections with speeds on the order of 100 km s{sup -1}. Remarkably, some of the brightenings rapidly develop into larger scale events, forming sheetlike structures that are eventually torn apart by the diverging flows in the filament channel and ejected in opposite directions. We interpret the brightenings as resulting from reconnections among filament-channel field lines having one footpoint located in the region of canceling flux. In some cases, the flow patterns that develop in the channel may bring successive horizontal loops together and cause a cascade to larger scales.

  19. Multiband superconductivity with competing intra- and interband pair channels

    NASA Astrophysics Data System (ADS)

    Kristoffel, N.; Rubin, P.

    2016-03-01

    In multiband superconductivity interband interaction channels creating the pairs of intraband (Wa) and interband (Wb) compositions can appear. Simultaneous functioning of these channels is investigated here. A three-band model where two similar bands (a; b) interact with the itinerant-band has been proposed. The mean field Hamiltonian incorporates three order parameters Δa; Δad; Δb1,2 genetically associated with dispersive bands. Calculated quasiparticle energies and operator averages lead to a coupled nonlinear equation system for the order parameters. Illustrative calculations versus temperature have been made for overlapping bands. At fixed parameters, the basic system has two independent solutions. The free energy has a complicated structure of extremal points. The interaction of channels with intra- and interband points is seen. These channels compete in general. From the point where the gap, type parameters associated with one channel become zero, the other continues as the first channel was logged out. The general behaviour of order parameters distribution is very sensible to Wb. Events of critical nature appear. Weakening of Wb stimulates the formation of closed bubbles built up by the same type parameters from different parallel solutions.

  20. Mechanism and Functional Significance of TRPC Channel Multimerization

    PubMed Central

    Villereal, Mitchel L.

    2007-01-01

    Ca2+ signaling regulates many important physiological events within a diverse set of living organisms. In particular, sustained Ca2+ signals play an important role in controlling cell proliferation, cell differentiation and the activation of immune cells. Two key elements for the generation of sustained Ca2+ signals are store-operated and receptor-operated Ca2+ channels that are activated downstream of phospholipase C (PLC) stimulation, in response to G-protein-coupled receptor or growth factor receptor stimulation. One goal of this review is to help clarify the role of canonical transient receptor potential (TRPC) proteins in the formation of native store-operated and native receptor-operated channels. Toward that end, data from studies of endogenous TRPC proteins will be reviewed in detail to highlight the strong case for the involvement of certain TRPC proteins in the formation of one subtype of store-operated channel, which exhibits a low Ca2+-selectivity, in contrast to the high Ca2+-selectivity exhibited by the CRAC subtype of store-operated channel. A second goal of this review is to highlight the growing body of evidence indicating that native store-operated and native receptor-operated channels are formed by the heteromultimerization of TRPC subunits. Furthermore, evidence will be provided to argue that some TRPC proteins are able to form multiple channel types. PMID:17158075

  1. Influence of discharge channel number on pseudospark discharge evolution

    NASA Astrophysics Data System (ADS)

    Naweed, A.; Kiefer, J.; Gavrilescu, C.; Neff, W.

    2000-04-01

    A multichannel pseudospark device is optimized as a long-life high-current switch. The special geometry of this device allows discharge plasma to accelerate away from the discharge channels that are distributed radially around a common hollow cathode. Comparative measurements are performed on 3 and 6 channel pseudospark devices to determine how the pseudospark characteristic low-erosive operation scales with the number of discharge channels used. In both devices the same critical charge per channel value of 5 mC is found to cause a transition from a glow-type discharge into an arc-like discharge. Despite observation of an arc-like discharge the low-erosive conduction is maintained at very large currents in both 3 and 6 channel setups. The observed critical charge value of 5 mC required to cause glow-to-arc transition (GAT) is higher than the corresponding single-channel charge value of 3.5 mC. For the whole parameter range the expanding plasma is observed to attain its maximum velocity at the GAT event.

  2. Littoral steering of deltaic channels

    NASA Astrophysics Data System (ADS)

    Nienhuis, Jaap H.; Ashton, Andrew D.; Giosan, Liviu

    2016-11-01

    The typically single-threaded channels on wave-influenced deltas show striking differences in their orientations, with some channels oriented into the incoming waves (e.g., Ombrone, Krishna), and others oriented away from the waves (e.g., Godavari, Sao Francisco). Understanding the controls on channel orientation is important as the channel location greatly influences deltaic morphology and sedimentology, both subaerially and subaqueously. Here, we explore channel orientation and consequent feedbacks with local shoreline dynamics using a plan-form numerical model of delta evolution. The model treats fluvial sediment delivery to a wave-dominated coast in two ways: 1) channels are assumed to prograde in a direction perpendicular to the local shoreline orientation and 2) a controlled fraction of littoral sediment transport can bypass the river mouth. Model results suggest that channels migrate downdrift when there is a significant net littoral transport and alongshore transport bypassing of the river mouth is limited. In contrast, river channels tend to orient themselves into the waves when fluvial sediment flux is relatively large, causing the shoreline of the downdrift delta flank to attain the orientation of maximum potential sediment transport for the incoming wave climate. Using model results, we develop a framework to estimate channel orientations for wave-influenced deltas that shows good agreement with natural examples. An increase in fluvial sediment input can cause a channel to reorient itself into incoming waves, behavior observed, for example, in the Ombrone delta in Italy. Our results can inform paleoclimate studies by linking channel orientation to fluvial sediment flux and wave energy. In particular, our approach provides a means to quantify past wave directions, which are notoriously difficult to constrain.

  3. 76 FR 55561 - Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-08

    ... Coast Guard District, Wrightsville Channel; Wrightsville Beach, NC in the Federal Register (76 FR 44877... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Wrightsville...

  4. Biological event composition

    PubMed Central

    2012-01-01

    Background In recent years, biological event extraction has emerged as a key natural language processing task, aiming to address the information overload problem in accessing the molecular biology literature. The BioNLP shared task competitions have contributed to this recent interest considerably. The first competition (BioNLP'09) focused on extracting biological events from Medline abstracts from a narrow domain, while the theme of the latest competition (BioNLP-ST'11) was generalization and a wider range of text types, event types, and subject domains were considered. We view event extraction as a building block in larger discourse interpretation and propose a two-phase, linguistically-grounded, rule-based methodology. In the first phase, a general, underspecified semantic interpretation is composed from syntactic dependency relations in a bottom-up manner. The notion of embedding underpins this phase and it is informed by a trigger dictionary and argument identification rules. Coreference resolution is also performed at this step, allowing extraction of inter-sentential relations. The second phase is concerned with constraining the resulting semantic interpretation by shared task specifications. We evaluated our general methodology on core biological event extraction and speculation/negation tasks in three main tracks of BioNLP-ST'11 (GENIA, EPI, and ID). Results We achieved competitive results in GENIA and ID tracks, while our results in the EPI track leave room for improvement. One notable feature of our system is that its performance across abstracts and articles bodies is stable. Coreference resolution results in minor improvement in system performance. Due to our interest in discourse-level elements, such as speculation/negation and coreference, we provide a more detailed analysis of our system performance in these subtasks. Conclusions The results demonstrate the viability of a robust, linguistically-oriented methodology, which clearly distinguishes

  5. Functional Expression of T-Type Ca2+ Channels in Spinal Motoneurons of the Adult Turtle

    PubMed Central

    Canto-Bustos, Martha; Loeza-Alcocer, Emanuel; González-Ramírez, Ricardo; Gandini, María A.; Delgado-Lezama, Rodolfo; Felix, Ricardo

    2014-01-01

    Voltage-gated Ca2+ (CaV) channels are transmembrane proteins comprising three subfamilies named CaV1, CaV2 and CaV3. The CaV3 channel subfamily groups the low-voltage activated Ca2+ channels (LVA or T-type) a significant role in regulating neuronal excitability. CaV3 channel activity may lead to the generation of complex patterns of action potential firing such as the postinhibitory rebound (PIR). In the adult spinal cord, these channels have been found in dorsal horn interneurons where they control physiological events near the resting potential and participate in determining excitability. In motoneurons, CaV3 channels have been found during development, but their functional expression has not yet been reported in adult animals. Here, we show evidence for the presence of CaV3 channel-mediated PIR in motoneurons of the adult turtle spinal cord. Our results indicate that Ni2+ and NNC55-0396, two antagonists of CaV3 channel activity, inhibited PIR in the adult turtle spinal cord. Molecular biology and biochemical assays revealed the expression of the CaV3.1 channel isotype and its localization in motoneurons. Together, these results provide evidence for the expression of CaV3.1 channels in the spinal cord of adult animals and show also that these channels may contribute to determine the excitability of motoneurons. PMID:25255145

  6. Topography of native SK channels revealed by force nanoscopy in living neurons.

    PubMed

    Maciaszek, Jamie L; Soh, Heun; Walikonis, Randall S; Tzingounis, Anastasios V; Lykotrafitis, George

    2012-08-15

    The spatial distribution of ion channels is an important determinant of neuronal excitability. However, there are currently no quantitative techniques to map endogenous ion channels with single-channel resolution in living cells. Here, we demonstrate that integration of pharmacology with single-molecule atomic force microscopy (AFM) allows for the high-resolution mapping of native potassium channels in living neurons. We focus on calcium-activated small conductance (SK) potassium channels, which play a critical role in brain physiology. By linking apamin, a toxin that specifically binds to SK channels, to the tip of an AFM cantilever, we are able to detect binding events between the apamin and SK channels. We find that native SK channels from rat hippocampal neurons reside primarily in dendrites as single entities and in pairs. We also show that SK channel dendritic distribution is dynamic and under the control of protein kinase A. Our study demonstrates that integration of toxin pharmacology with single-molecule AFM can be used to quantitatively map individual native ion channels in living cells, and thus provides a new tool for the study of ion channels in cellular physiology. PMID:22895725

  7. Voltage-gated Na(+) channels in chemoreceptor afferent neurons--potential roles and changes with development.

    PubMed

    Donnelly, David F

    2013-01-01

    Carotid body chemoreceptors increase their action potential (AP) activity in response to a decrease in arterial oxygen tension and this response increases in the post-natal period. The initial transduction site is likely the glomus cell which responds to hypoxia with an increase in intracellular calcium and secretion of multiple neurotransmitters. Translation of this secretion to AP spiking levels is determined by the excitability of the afferent nerve terminals that is largely determined by the voltage-dependence of activation of Na(+) channels. In this review, we examine the biophysical characteristics of Na(+) channels present at the soma of chemoreceptor afferent neurons with the assumption that similar channels are present at nerve terminals. The voltage dependence of this current is consistent with a single Na(+) channel isoform with activation around the resting potential and with about 60-70% of channels in the inactive state around the resting potential. Channel openings, due to transitions from inactive/open or closed/open states, may serve to amplify external depolarizing events or generate, by themselves, APs. Over the first two post-natal weeks, the Na(+) channel activation voltage shifts to more negative potentials, thus enhancing the amplifying action of Na(+) channels on depolarization events and increasing membrane noise generated by channel transitions. This may be a significant contributor to maturation of chemoreceptor activity in the post-natal period.

  8. Mirrored serpentine flow channels for fuel cell

    SciTech Connect

    Rock, Jeffrey Allan

    2000-08-08

    A PEM fuel cell having serpentine flow field channels wherein the input/inlet legs of each channel border the input/inlet legs of the next adjacent channels in the same flow field, and the output/exit legs of each channel border the output/exit legs of the next adjacent channels in the same flow field. The serpentine fuel flow channels may be longer, and may contain more medial legs, than the serpentine oxidant flow channels.

  9. Tidal disruption events

    NASA Astrophysics Data System (ADS)

    Levan, A.

    2014-07-01

    Tidal disruption events (TDEs) provide a powerful probe of many astrophysical processes. They occur when the powerful tidal field around a black hole disrupts a passing star which is subsequently accreted. The resulting signal is a powerful X-ray, UV/opt and possibly even radio source, that provides us with a view of accretion aroud supermassive black holes from switch-on to switch-off over the timescale of years. TDEs probe accretion physics, the ubquity of black holes in galactic nuclei and dynamics in their cores, offering a novel route to addressing these issues. I will review observations of TDEs over the past decade, outlining how samples of candidates have been gradually building, and how they can be identified against other more common transient events. I will also discuss the implications of the discovery of a population of TDEs apparently launching relativisitc jets, and how these powerful transients may be detected in upcoming X-ray to radio surveys.

  10. Single event mass spectrometry

    DOEpatents

    Conzemius, Robert J.

    1990-01-16

    A means and method for single event time of flight mass spectrometry for analysis of specimen materials. The method of the invention includes pulsing an ion source imposing at least one pulsed ion onto the specimen to produce a corresponding emission of at least one electrically charged particle. The emitted particle is then dissociated into a charged ion component and an uncharged neutral component. The ion and neutral components are then detected. The time of flight of the components are recorded and can be used to analyze the predecessor of the components, and therefore the specimen material. When more than one ion particle is emitted from the specimen per single ion impact, the single event time of flight mass spectrometer described here furnis This invention was made with Government support under Contract No. W-7405-ENG82 awarded by the Department of Energy. The Government has certain rights in the invention.

  11. Ordinary High Water Mark in ephemeral and intermittent channels in the arid southwestern United States

    NASA Astrophysics Data System (ADS)

    Curtis, K. E.; Lichvar, R.; Dixon, L.

    2010-12-01

    The Ordinary High Water Mark (OHWM) is important for regulating stream channels, as it defines the lateral extent of non-wetland waters, as defined under Waters of the United States in the Clean Water Act (33 CFR Part 328.3). Prior to this study, little was known about the OHWM and geomorphically effective events in arid southwest ephemeral and intermittent channels. The hydrogeomorphic floodplain features and flow dynamics are challenging to identify in these channels because of the unstable channel morphology, flashy flood events, and lack of gage data. Through field surveys, LiDAR high-resolution topography data collection, HEC-RAS flow modeling, analysis of aerial photography, and determination of recurrence intervals using gage data, we have developed a methodology to identify the hydrogeomorphic floodplain units and delineate the OHWM. The hydrogeomorphic floodplain units include a migratory low-flow channel, an active floodplain associated with low to moderate discharge events, and a low terrace inundated by moderate to high floods. We identified primary OHWM indicators such as a break in slope, a change in sediment texture, and a change in vegetation characteristics that create a repeatable and reliable signature in the channel morphology that is associated with the OHW boundary between the active floodplain and the low terrace. Secondary indicators such as drift, ripples, and silt deposits are randomly distributed throughout the channel and cannot be linked to a particular inundation extent. In an analysis of 14 gaged ephemeral and intermittent channels, we determined that the recurrence intervals varied from <1 to 15.5 yr. Lower recurrence intervals were typically associated with more stable channels, while channels with a sandy, erodable substrate had higher recurrence intervals. A more complete understanding of the channel morphology and the highly variable OHW recurrence intervals allows more reliable and repeatable delineations in southwest ephemeral

  12. Staged Event Architecture

    SciTech Connect

    Hoschek, Wolfgang; Berket, Karlo

    2005-05-30

    Sea is a framework for a Staged Event Architecture, designed around non-blocking asynchronous communication facilities that are decoupled from the threading model chosen by any given application, Components for P networking and in-memory communication are provided. The Sea Java library encapsulates these concepts. Sea is used to easily build efficient and flexible low-level network clients and servers, and in particular as a basic communication substrate for Peer-to-Peer applications.

  13. The EMBL-EBI channel.

    PubMed

    McEntyre, Jo; Birney, Ewan

    2016-01-01

    This editorial introduces the EMBL-EBI channel in F1000Research. The aims of the channel are to present EMBL-EBI outputs and collate research published on F1000Research contributed, in whole or in part, EMBL-EBI researchers. PMID:26913196

  14. A channel simulator design study

    NASA Technical Reports Server (NTRS)

    Devito, D. M.; Goutmann, M. M.; Harper, R. C.

    1971-01-01

    A propagation path simulator was designed for the channel between a Tracking and Data Relay Satellite in geostationary orbit and a user spacecraft orbiting the earth at an altitude between 200 and 4000 kilometers. The simulator is required to duplicate the time varying parameters of the propagation channel.

  15. Phenomics of Cardiac Chloride Channels

    PubMed Central

    Duan, Dayue Darrel

    2014-01-01

    Forward genetic studies have identified several chloride (Cl−) channel genes, including CFTR, ClC-2, ClC-3, CLCA, Bestrophin, and Ano1, in the heart. Recent reverse genetic studies using gene targeting and transgenic techniques to delineate the functional role of cardiac Cl− channels have shown that Cl− channels may contribute to cardiac arrhythmogenesis, myocardial hypertrophy and heart failure, and cardioprotection against ischemia reperfusion. The study of physiological or pathophysiological phenotypes of cardiac Cl− channels, however, is complicated by the compensatory changes in the animals in response to the targeted genetic manipulation. Alternatively, tissue-specific conditional or inducible knockout or knockin animal models may be more valuable in the phenotypic studies of specific Cl− channels by limiting the effect of compensation on the phenotype. The integrated function of Cl− channels may involve multiprotein complexes of the Cl− channel subproteome. Similar phenotypes can be attained from alternative protein pathways within cellular networks, which are influenced by genetic and environmental factors. The phenomics approach, which characterizes phenotypes as a whole phenome and systematically studies the molecular changes that give rise to particular phenotypes achieved by modifying the genotype under the scope of genome/proteome/phenome, may provide more complete understanding of the integrated function of each cardiac Cl− channel in the context of health and disease. PMID:23720326

  16. Chloride Channels of Intracellular Membranes

    PubMed Central

    Edwards, John C.; Kahl, Christina R.

    2010-01-01

    Proteins implicated as intracellular chloride channels include the intracellular ClC proteins, the bestrophins, the cystic fibrosis transmembrane conductance regulator, the CLICs, and the recently described Golgi pH regulator. This paper examines current hypotheses regarding roles of intracellular chloride channels and reviews the evidence supporting a role in intracellular chloride transport for each of these proteins. PMID:20100480

  17. Some Aviation Growth Events

    NASA Technical Reports Server (NTRS)

    Spearman, M. Leroy

    2002-01-01

    The growth of aviation since the first flight of a heavier-than-air powered manned vehicle in 1903 has been somewhat remarkable. Some of the events that have influenced this growth are reviewed in this paper. This review will include some events prior to World War I; the influence of the war itself; the events during the post-war years including the establishment of aeronautical research laboratories; and the influence of World War II which, among other things, introduced new technologies that included rocket and jet propulsion and supersonic aerodynamics. The subsequent era of aeronautical research and the attendant growth in aviation over the past half century will be reviewed from the view point of the author who, since 1944, has been involved in the NACA/NASA aeronautical research effort at what is now the Langley Research Center in Hampton, Virginia. The review will discuss some of the research programs related to the development of some experimental aircraft, the Century series of fighter aircraft, multi-mission aircraft, advanced military aircraft and missiles, advanced civil aircraft, supersonic transports, spacecraft and others.

  18. Young Channel, Old Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 18 March 2004

    The Odyssey spacecraft has completed a full Mars year of observations of the red planet. For the next several weeks the Image of the Day will look back over this first mars year. It will focus on four themes: 1) the poles - with the seasonal changes seen in the retreat and expansion of the caps; 2) craters - with a variety of morphologies relating to impact materials and later alteration, both infilling and exhumation; 3) channels - the clues to liquid surface flow; and 4) volcanic flow features. While some images have helped answer questions about the history of Mars, many have raised new questions that are still being investigated as Odyssey continues collecting data as it orbits Mars.

    Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark.

    This daytime IR image was collected on February 3, 2003 during the northern summer season. This image shows a younger channel cutting through an older crater.

    Image information: IR instrument. Latitude 30.8, Longitude 19 East (341 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System

  19. Channel Floor Yardangs

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 19 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    The yardangs in this image are forming in channel floor deposits. The channel itself is funneling the wind to cause the erosion.

    Image information: VIS instrument. Latitude 4.5, Longitude 229.7 East (133.3 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are

  20. Development of Memory for Events.

    ERIC Educational Resources Information Center

    Ratner, Hilary Horn; And Others

    1986-01-01

    Examines development of event memory by determining how personally experienced events with two types of structure were reported by kindergartners and adults. Events in making and playing with clay were organized causally and temporally. Results show that adults and children used a goal-based hierarchical structure to remember events, although use…

  1. Lipid Regulation of Sodium Channels.

    PubMed

    D'Avanzo, N

    2016-01-01

    The lipid landscapes of cellular membranes are complex and dynamic, are tissue dependent, and can change with the age and the development of a variety of diseases. Researchers are now gaining new appreciation for the regulation of ion channel proteins by the membrane lipids in which they are embedded. Thus, as membrane lipids change, for example, during the development of disease, it is likely that the ionic currents that conduct through the ion channels embedded in these membranes will also be altered. This chapter provides an overview of the complex regulation of prokaryotic and eukaryotic voltage-dependent sodium (Nav) channels by fatty acids, sterols, glycerophospholipids, sphingolipids, and cannabinoids. The impact of lipid regulation on channel gating kinetics, voltage-dependence, trafficking, toxin binding, and structure are explored for Nav channels that have been examined in heterologous expression systems, native tissue, and reconstituted into artificial membranes. Putative mechanisms for Nav regulation by lipids are also discussed. PMID:27586290

  2. Targeting potassium channels in cancer

    PubMed Central

    2014-01-01

    Potassium channels are pore-forming transmembrane proteins that regulate a multitude of biological processes by controlling potassium flow across cell membranes. Aberrant potassium channel functions contribute to diseases such as epilepsy, cardiac arrhythmia, and neuromuscular symptoms collectively known as channelopathies. Increasing evidence suggests that cancer constitutes another category of channelopathies associated with dysregulated channel expression. Indeed, potassium channel–modulating agents have demonstrated antitumor efficacy. Potassium channels regulate cancer cell behaviors such as proliferation and migration through both canonical ion permeation–dependent and noncanonical ion permeation–independent functions. Given their cell surface localization and well-known pharmacology, pharmacological strategies to target potassium channel could prove to be promising cancer therapeutics. PMID:25049269

  3. Requirements for signaling channel authentication

    SciTech Connect

    Tarman, T.D.

    1995-12-11

    This contribution addresses requirements for ATM signaling channel authentication. Signaling channel authentication is an ATM security service that binds an ATM signaling message to its source. By creating this binding, the message recipient, and even a third party, can confidently verify that the message originated from its claimed source. This provides a useful mechanism to mitigate a number of threats. For example, a denial of service attack which attempts to tear-down an active connection by surreptitiously injecting RELEASE or DROP PARTY messages could be easily thwarted when authenticity assurances are in place for the signaling channel. Signaling channel authentication could also be used to provide the required auditing information for accurate billing which is impervious to repudiation. Finally, depending on the signaling channel authentication mechanism, end-to-end integrity of the message (or at least part of it) can be provided. None of these capabilities exist in the current specifications.

  4. Voltage-gated Proton Channels

    PubMed Central

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  5. Voltage-gated proton channels.

    PubMed

    Decoursey, Thomas E

    2012-04-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely, the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance approximately 10(3) times smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn(2+) (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B-lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H(+) for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens.

  6. Analysis and functional implications of phosphorylation of neuronal voltage-gated potassium channels

    PubMed Central

    Cerda, Oscar; Trimmer, James S.

    2012-01-01

    Phosphorylation is the most common and abundant posttranslational modification to eukaryotic proteins, regulating a plethora of dynamic cellular processes. Here, we review and discuss recent advances in our knowledge of the breadth and importance of reversible phosphorylation in regulating the expression, localization and function of mammalian neuronal voltage-gated potassium (Kv) channels, key regulators of neuronal function. We highlight the role of modern mass spectrometric techniques and phosphospecific antibodies that reveal the extent and nature of phosphorylation at specific sites in Kv channels. We also emphasize the role of reversible phosphorylation in dynamically regulating diverse aspects of Kv channel biology. Finally, we discuss as important future directions the determination of the mechanistic basis for how altering phosphorylation state affects Kv channel expression, localization and function, the nature of macromolecular signaling complexes containing Kv channels and enzymes regulating their phosphorylation state, and the specific role of Kv channel phosphorylation in regulating neuronal function during physiological and pathophysiological events. PMID:20600597

  7. Molecular basis of ion permeability in a voltage-gated sodium channel.

    PubMed

    Naylor, Claire E; Bagnéris, Claire; DeCaen, Paul G; Sula, Altin; Scaglione, Antonella; Clapham, David E; Wallace, B A

    2016-04-15

    Voltage-gated sodium channels are essential for electrical signalling across cell membranes. They exhibit strong selectivities for sodium ions over other cations, enabling the finely tuned cascade of events associated with action potentials. This paper describes the ion permeability characteristics and the crystal structure of a prokaryotic sodium channel, showing for the first time the detailed locations of sodium ions in the selectivity filter of a sodium channel. Electrostatic calculations based on the structure are consistent with the relative cation permeability ratios (Na(+) ≈ Li(+) ≫ K(+), Ca(2+), Mg(2+)) measured for these channels. In an E178D selectivity filter mutant constructed to have altered ion selectivities, the sodium ion binding site nearest the extracellular side is missing. Unlike potassium ions in potassium channels, the sodium ions in these channels appear to be hydrated and are associated with side chains of the selectivity filter residues, rather than polypeptide backbones. PMID:26873592

  8. Numerical reconstruction of the quantal event at nicotinic synapses.

    PubMed Central

    Wathey, J C; Nass, M M; Lester, H A

    1979-01-01

    To test our present quantitative knowledge of nicotinic transmission, we reconstruct the postsynaptic conductance change that results after a presynaptic nerve terminal liberates a quantum of acetylcholine (ACh) into the synaptic cleft. The theory assumes that ACh appears suddenly in the cleft and that is subsequent fate is determined by radial diffusion, by enzymatic hydrolysis, and by binding to receptors. Each receptor has one channel and two ACh binding sites; the channel opens when both sites are occupied and the rate-limiting step id the binding and dissociation of the second ACh molecule. The calculations reproduce the experimentally measured growth phase (200 microseconds), peak number of open channels (2,000), and exponential decay phase. The time constant of the decay phase exceeds the channel duration by approximately equal to 20%. The normal event is highly localized: at the peak, two-thirds of the open channels are within an area of 0.15 micrometer 2. This represents 75% of the available channels within this area. The model also simulates voltage and temperature dependence and effects of inactivating esterase and receptors. The calculations show that in the absence of esterase, transmitter is buffered by binding to receptors and the postsynaptic response can be potentiated. PMID:262376

  9. Methods of channeling simulation

    SciTech Connect

    Barrett, J.H.

    1989-06-01

    Many computer simulation programs have been used to interpret experiments almost since the first channeling measurements were made. Certain aspects of these programs are important in how accurately they simulate ions in crystals; among these are the manner in which the structure of the crystal is incorporated, how any quantity of interest is computed, what ion-atom potential is used, how deflections are computed from the potential, incorporation of thermal vibrations of the lattice atoms, correlations of thermal vibrations, and form of stopping power. Other aspects of the programs are included to improve the speed; among these are table lookup, importance sampling, and the multiparameter method. It is desirable for programs to facilitate incorporation of special features of interest in special situations; examples are relaxations and enhanced vibrations of surface atoms, easy substitution of an alternate potential for comparison, change of row directions from layer to layer in strained-layer lattices, and different vibration amplitudes for substitutional solute or impurity atoms. Ways of implementing all of these aspects and features and the consequences of them will be discussed. 30 refs., 3 figs.

  10. Multiple conductance states of the light-activated channel of Limulus ventral photoreceptors. Alteration of conductance state during light

    PubMed Central

    1991-01-01

    The properties of light-dependent channels in Limulus ventral photoreceptors have been studied in cell-attached patches. Two sizes of single-channel events are seen during illumination. Previous work has characterized the large (40 pS) events; the goal of the current work was to characterize the small (15 pS) events and determine their relationship to the large events. The small events are activated by light rather than as a secondary result of the change in membrane voltage during light. The mean open time of the small events is 1.34 +/- 0.49 ms (mean +/- SD, n = 15), approximately 50% of that of the large events. The large and small events have the same reversal potential and a similar dependence of open-state probability on voltage. Evidence that these events are due to different conductance states of the same channel comes from analysis of relatively infrequent events showing a direct transition between the 15 and 40-pS levels. Furthermore, large and small events do not superpose, even at positive voltages when the probability of being open is very high, as would be predicted if the two-sized events were due to independent channels. Expression of the different conductance states is not random; during steady illumination there are alternating periods of several hundred milliseconds in which there are consecutive, sequential large events followed by periods in which there are consecutive, sequential small events. At early times during the response to a step of light, the large conductance state is preferentially expressed. At later times, there is an increase in the relative contribution of the low conductance state. These findings indicate that there is a process that changes the preferred conductance state of the channel. This alteration has functional importance in the process of light adaptation. PMID:1875187

  11. M channel enhancers and physiological M channel block.

    PubMed

    Linley, John E; Pettinger, Louisa; Huang, Dongyang; Gamper, Nikita

    2012-02-15

    M-type (Kv7, KCNQ) K(+) channels control the resting membrane potential of many neurons, including peripheral nociceptive sensory neurons. Several M channel enhancers were suggested as prospective analgesics, and targeting M channels specifically in peripheral nociceptors is a plausible strategy for peripheral analgesia. However, receptor-induced inhibition of M channels in nociceptors is often observed in inflammation and may contribute to inflammatory pain. Such inhibition is predominantly mediated by phospholipase C. We investigated four M channel enhancers (retigabine, flupirtine, zinc pyrithione and H(2)O(2)) for their ability to overcome M channel inhibition via two phospholipase C-mediated mechanisms, namely depletion of membrane phosphatidylinositol 4,5-bisphosphate (PIP(2)) and a rise in intracellular Ca(2+) (an action mediated by calmodulin). Data from overexpressed Kv7.2/Kv7.3 heteromers and native M currents in dorsal root ganglion neurons suggest the following conclusions. (i) All enhancers had a dual effect on M channel activity, a negative shift in voltage dependence and an increase of the maximal current at saturating voltages. The enhancers differed in their efficacy to produce these effects. (ii) Both PIP(2) depletion and Ca(2+)/calmodulin strongly reduced the M current amplitude; however, at voltages near the threshold for M channel activation (-60 mV) all enhancers were able to restore M channel activity to a control level or above, while at saturating voltages the effects were more variable. (iii) Receptor-mediated inhibition of M current in nociceptive dorsal root ganglion neurons did not reduce the efficacy of retigabine or flupirtine to hyperpolarize the resting membrane potential. In conclusion, we show that all four M channel enhancers tested could overcome both PIP(2) and Ca(2+)-calmodulin-induced inhibition of Kv7.2/7.3 at voltages close to the threshold for action potential firing (-60 mV) but generally had reduced efficacy at a

  12. Single-Channel Recording of Ligand-Gated Ion Channels.

    PubMed

    Plested, Andrew J R

    2016-01-01

    Single-channel recordings reveal the microscopic properties of individual ligand-gated ion channels. Such recordings contain much more information than measurements of ensemble behavior and can yield structural and functional information about the receptors that participate in fast synaptic transmission in the brain. With a little care, a standard patch-clamp electrophysiology setup can be adapted for single-channel recording in a matter of hours. Thenceforth, it is a realistic aim to record single-molecule activity with microsecond resolution from arbitrary cell types, including cell lines and neurons. PMID:27480725

  13. Quantum dot conjugates in a sub-micrometer fluidic channel

    DOEpatents

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2008-07-29

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  14. Quantum dot conjugates in a sub-micrometer fluidic channel

    DOEpatents

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2010-04-13

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  15. Sub-micrometer fluidic channel for measuring photon emitting entities

    DOEpatents

    Stavis, Samuel M; Edel, Joshua B; Samiee, Kevan T; Craighead, Harold G

    2014-11-18

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  16. Heterogeneity of Calcium Channel/cAMP-Dependent Transcriptional Activation.

    PubMed

    Kobrinsky, Evgeny

    2015-01-01

    The major function of the voltage-gated calcium channels is to provide the Ca(2+) flux into the cell. L-type voltage-gated calcium channels (Cav1) serve as voltage sensors that couple membrane depolarization to many intracellular processes. Electrical activity in excitable cells affects gene expression through signaling pathways involved in the excitation-transcription (E-T) coupling. E-T coupling starts with activation of the Cav1 channel and results in initiation of the cAMP-response element binding protein (CREB)-dependent transcription. In this review we discuss the new quantitative approaches to measuring E-T signaling events. We describe the use of wavelet transform to detect heterogeneity of transcriptional activation in nuclei. Furthermore, we discuss the properties of discovered microdomains of nuclear signaling associated with the E-T coupling and the basis of the frequency-dependent transcriptional regulation.

  17. Event selection services in ATLAS

    NASA Astrophysics Data System (ADS)

    Cranshaw, J.; Cuhadar-Donszelmann, T.; Gallas, E.; Hrivnac, J.; Kenyon, M.; McGlone, H.; Malon, D.; Mambelli, M.; Nowak, M.; Viegas, F.; Vinek, E.; Zhang, Q.

    2010-04-01

    ATLAS has developed and deployed event-level selection services based upon event metadata records ("TAGS") and supporting file and database technology. These services allow physicists to extract events that satisfy their selection predicates from any stage of data processing and use them as input to later analyses. One component of these services is a web-based Event-Level Selection Service Interface (ELSSI). ELSSI supports event selection by integrating run-level metadata, luminosity-block-level metadata (e.g., detector status and quality information), and event-by-event information (e.g., triggers passed and physics content). The list of events that survive after some selection criterion is returned in a form that can be used directly as input to local or distributed analysis; indeed, it is possible to submit a skimming job directly from the ELSSI interface using grid proxy credential delegation. ELSSI allows physicists to explore ATLAS event metadata as a means to understand, qualitatively and quantitatively, the distributional characteristics of ATLAS data. In fact, the ELSSI service provides an easy interface to see the highest missing ET events or the events with the most leptons, to count how many events passed a given set of triggers, or to find events that failed a given trigger but nonetheless look relevant to an analysis based upon the results of offline reconstruction, and more. This work provides an overview of ATLAS event-level selection services, with an emphasis upon the interactive Event-Level Selection Service Interface.

  18. Safeguards summary event list (SSEL): Pre-NRC through December 31, 1988

    SciTech Connect

    Not Available

    1989-07-01

    The Safeguards Summary Event List (SSEL) provides brief summaries of several hundred safeguards-related events involving nuclear material or facilities regulated by the US Nuclear Regulatory Commission (NRC). Because of public interest, also included are events reported involving byproduct material which is exempt from safeguards requirements. Events are described under the categories of bomb-related, intrusion, missing and/or allegedly stolen, transportation, tampering/vandalism, arson, firearms, radiological sabotage, nonradiological sabotage, alcohol and drugs, and miscellaneous. The information contained in the event descriptions is derived primarily from official NRC reporting channels.

  19. Safeguards Summary Event List (SSEL), pre-NRC through December 31, 1989

    SciTech Connect

    Not Available

    1990-07-01

    The Safeguards Summary Event List (SSEL) provides brief summaries of several hundred safeguards-related events involving nuclear material or facilities regulated by the US Nuclear Regulatory Commission (NRC). Because of public interest, the Miscellaneous category includes a few events which involve either source material, byproduct material, or natural uranium which are exempt from safeguards requirements. Events are described under the categories of bomb-related, intrusion, missing and/or allegedly stolen, transportation, tampering/vandalism, arson, firearms, radiological sabotage, nonradiological sabotage, alcohol and drugs (involving reactor operators, security force members, or management persons), and miscellaneous. The information contained in the event descriptions is derived primarily from official NRC reporting channels.

  20. Ion channels in artificial bolaamphiphile membranes deposited on sensor chips: optical detection in an ion-channel-based biosensor

    NASA Astrophysics Data System (ADS)

    Schalkhammer, Thomas G. M.; Weiss-Wichert, Christof; Smetazko, Michaela M.; Valina-Saba, Miriam

    1997-06-01

    Signal amplification using labels should be replaced by a technique monitoring the biochemical binding event directly. The use of a ligand coupled to an artificial gated membrane ion channel is a new promising strategy. Binding of protein- or DNA/RNA-analytes at ligand modified peptide channels results in an on/off-response of the channel current due to channel closure or distortion. The sensor consists of stable transmembrane channels with a ligand bound covalently at the peptide channel entrance, a sensor chip with a photostructurized hydrophobic polymer frame, a hydrophilic ion conducting membrane support, a lipid membrane incorporating the engineered ion channels, and a current amplifier or a sensitive fluorescence monitor. Detection of channel opening or closure can ether be obtained by directly monitoring membrane conductivity or a transient change of pH or ion concentration within the membrane compartment. This change can be induced by electrochemical or optical means and its decay is directly correlated to the permeability of the membrane. The ion concentration in the sub membrane compartment was monitored by incorporation of fluorescent indicator dyes. To obtain the stable sensor membrane the lipid layer had to be attached on a support and the floating of the second lipid membrane on top of the first one had to be prevented. Both problems do not occur using our new circular C44-C76 bolaamphiphilic lipids consisting of a long hydrophobic core region and two hydrophilic heads. Use of maleic ester-head groups enabled us to easily modify the lipids with amines, thioles, alcohols, phosphates, boronic acid as well as fluorescent dyes. The properties of these membranes were studied using LB and fluorescence techniques. Based on this detection principle miniaturized sensor chips with significantly enhanced sensitivity and large multi analyte arrays are under construction.

  1. Event mapping meeting

    SciTech Connect

    Eaton, L.; Mason, D.

    1997-02-20

    A one-day meeting was held by the authors to evaluate how the strategic lab workshops would tie to this year`s tactical planning exercise. In particular, they wanted to find recent events that would support the tactical goal decisions of the Lab, and they wanted to find events that verify the Lab`s present course. The events which are each briefly discussed are: Galvin Commission recommends consolidating DOE defense labs (1995); Congressional subcommittee staff force budget cuts and consolidation (1995); 28% of DOE/DP budget held back pending completion of a clear 5-yr plan for nukes (1995); DOD and DOE focus on dual use (1995); LANL work includes weapons rebuilds (1995); LANL chosen by DOE to develop and test advanced remediation techniques (1995); AGEX/DARHT Project is stopped by suits from environmental activities (1996); Non-proliferation treaty renewed (1996); US complies with Comprehensive Test Ban Treaty (1996); Capability based deterrence policy put into place (1998); Stockpile shrinks to approximately 2000 weapons (2005); DOE weapons labs re-chartered as true national labs (1996); DOE terminates all nuclear weapons testing support (1996); Industrial projects at LANL up 20% from previous year (1997); NIST-ATP Program becomes an interagency process (1997); DOE warns that spent commercial reactor fuels is a major proliferation threat (1998); Non-lethal weapons work helps to reshape LANL image (1998); Global warning theory proven (2005); Overall US spending on science has been flat or decreasing for three years (1998); and Economic role of LANL in northern New Mexico declines (2005).

  2. Tectonic events in Greenland

    NASA Astrophysics Data System (ADS)

    Dahl-Jensen, T.; Voss, P.; Larsen, T.; Pinna, L.

    2012-12-01

    In Greenland a station separation of around 400km mean that many earthquakes are only detected on one or two stations. The development of the seismic monitoring have gone from having only three seismic stations in Greenland up to the late 1990'ies, till today where there are 18 permanent stations. All stations are equipped with broadband sensors and all of the permanent stations transmit data in real time. The recent major improvement of the seismic monitoring is performed by the Greenland ice sheet monitoring network (GLISN, http://glisn.info). The primary goal of GLISN is to provide broadband seismic data for the detection of glacial earthquakes. GLISN is now fully implemented with Iridium real time data transfer is in operation at five stations. In the Ammassalik region in Southeast Greenland, where small earthquakes often are felt, data from a temporary additional station has been utilized for a study covering 9 months in 2008/9. In this period 62 local earthquakes have been analyzed and re-located. Some of the events had formerly been located from distant stations by using a universal earth model. The result of this localization was a scattered distribution of the events in the region. The locations have now been improved by using a local earth model along with phase readings from two local stations not previously included; ANG in Tasiilaq and ISOG in Isortoq. From relocating the events two zones with a higher degree of seismicity than in the rest of the region are observed. The first zone is located by felsic intrusions. The second zone is at the boundary between the Archaean Craton and the Ammasalik region where reworked Archaean gneisses are dominating the geology. During the analysis it was observed that the additional information from the local stations are of great importance for the result. Active broad band stations in Greenland

  3. Information geometry of Gaussian channels

    SciTech Connect

    Monras, Alex; Illuminati, Fabrizio

    2010-06-15

    We define a local Riemannian metric tensor in the manifold of Gaussian channels and the distance that it induces. We adopt an information-geometric approach and define a metric derived from the Bures-Fisher metric for quantum states. The resulting metric inherits several desirable properties from the Bures-Fisher metric and is operationally motivated by distinguishability considerations: It serves as an upper bound to the attainable quantum Fisher information for the channel parameters using Gaussian states, under generic constraints on the physically available resources. Our approach naturally includes the use of entangled Gaussian probe states. We prove that the metric enjoys some desirable properties like stability and covariance. As a by-product, we also obtain some general results in Gaussian channel estimation that are the continuous-variable analogs of previously known results in finite dimensions. We prove that optimal probe states are always pure and bounded in the number of ancillary modes, even in the presence of constraints on the reduced state input in the channel. This has experimental and computational implications. It limits the complexity of optimal experimental setups for channel estimation and reduces the computational requirements for the evaluation of the metric: Indeed, we construct a converging algorithm for its computation. We provide explicit formulas for computing the multiparametric quantum Fisher information for dissipative channels probed with arbitrary Gaussian states and provide the optimal observables for the estimation of the channel parameters (e.g., bath couplings, squeezing, and temperature).

  4. Ion Channels in Brain Metastasis

    PubMed Central

    Klumpp, Lukas; Sezgin, Efe C.; Eckert, Franziska; Huber, Stephan M.

    2016-01-01

    Breast cancer, lung cancer and melanoma exhibit a high metastatic tropism to the brain. Development of brain metastases severely worsens the prognosis of cancer patients and constrains curative treatment options. Metastasizing to the brain by cancer cells can be dissected in consecutive processes including epithelial–mesenchymal transition, evasion from the primary tumor, intravasation and circulation in the blood, extravasation across the blood–brain barrier, formation of metastatic niches, and colonization in the brain. Ion channels have been demonstrated to be aberrantly expressed in tumor cells where they regulate neoplastic transformation, malignant progression or therapy resistance. Moreover, many ion channel modulators are FDA-approved drugs and in clinical use proposing ion channels as druggable targets for future anti-cancer therapy. The present review article aims to summarize the current knowledge on the function of ion channels in the different processes of brain metastasis. The data suggest that certain channel types involving voltage-gated sodium channels, ATP-release channels, ionotropic neurotransmitter receptors and gap junction-generating connexins interfere with distinct processes of brain metastazation. PMID:27618016

  5. ATP release through pannexon channels.

    PubMed

    Dahl, Gerhard

    2015-07-01

    Extracellular adenosine triphosphate (ATP) serves as a signal for diverse physiological functions, including spread of calcium waves between astrocytes, control of vascular oxygen supply and control of ciliary beat in the airways. ATP can be released from cells by various mechanisms. This review focuses on channel-mediated ATP release and its main enabler, Pannexin1 (Panx1). Six subunits of Panx1 form a plasma membrane channel termed 'pannexon'. Depending on the mode of stimulation, the pannexon has large conductance (500 pS) and unselective permeability to molecules less than 1.5 kD or is a small (50 pS), chloride-selective channel. Most physiological and pathological stimuli induce the large channel conformation, whereas the small conformation so far has only been observed with exclusive voltage activation of the channel. The interaction between pannexons and ATP is intimate. The pannexon is not only the conduit for ATP, permitting ATP efflux from cells down its concentration gradient, but the pannexon is also modulated by ATP. The channel can be activated by ATP through both ionotropic P2X as well as metabotropic P2Y purinergic receptors. In the absence of a control mechanism, this positive feedback loop would lead to cell death owing to the linkage of purinergic receptors with apoptotic processes. A control mechanism preventing excessive activation of the purinergic receptors is provided by ATP binding (with low affinity) to the Panx1 protein and gating the channel shut. PMID:26009770

  6. Ion Channels in Brain Metastasis.

    PubMed

    Klumpp, Lukas; Sezgin, Efe C; Eckert, Franziska; Huber, Stephan M

    2016-01-01

    Breast cancer, lung cancer and melanoma exhibit a high metastatic tropism to the brain. Development of brain metastases severely worsens the prognosis of cancer patients and constrains curative treatment options. Metastasizing to the brain by cancer cells can be dissected in consecutive processes including epithelial-mesenchymal transition, evasion from the primary tumor, intravasation and circulation in the blood, extravasation across the blood-brain barrier, formation of metastatic niches, and colonization in the brain. Ion channels have been demonstrated to be aberrantly expressed in tumor cells where they regulate neoplastic transformation, malignant progression or therapy resistance. Moreover, many ion channel modulators are FDA-approved drugs and in clinical use proposing ion channels as druggable targets for future anti-cancer therapy. The present review article aims to summarize the current knowledge on the function of ion channels in the different processes of brain metastasis. The data suggest that certain channel types involving voltage-gated sodium channels, ATP-release channels, ionotropic neurotransmitter receptors and gap junction-generating connexins interfere with distinct processes of brain metastazation. PMID:27618016

  7. Microbial Senses and Ion Channels

    NASA Astrophysics Data System (ADS)

    Kung, Ching; Zhou, Xin-Liang; Su, Zhen-Wei; Haynes, W. John; Loukin, Sephan H.; Saimi, Yoshiro

    The complexity of animals and plants is due largely to cellular arrangement. The structures and activities of macromolecules had, however, evolved in early microbes long before the appearance of this complexity. Among such molecules are those that sense light, heat, force, water, and ligands. Though historically and didactically associated with the nervous system, ion channels also have deep evolutionary roots. For example, force sensing with channels, which likely began as water sensing through membrane stretch generated by osmotic pressure, must be ancient and is universal in extant species. Extant microbial species, such as the model bacterium Escherichia coli and yeast Saccharomyces cerevisiae, are equipped with stretch-activated channels. The ion channel proteins MscL and MscS show clearly that these bacterial channels receive stretch forces from the lipid bilayer. TRPY1, the mechanosensitive channel in yeast, is being developed towards a similar basic understanding of channels of the TRP (transientreceptor- potential) superfamily. TRPY1 resides in the vacuolar membrane and releases Ca2+ from the vacuole to the cytoplasm upon hyperosmotic shock. Unlike in most TRP preparations from animals, the mechanosensitivity of TRPY1 can be examined directly under patch clamp in either whole-vacuole mode or excised patch mode. The combination of direct biophysical examination in vitro with powerful microbial genetics in vivo should complement the study of mechanosensations of complex animals and plants.

  8. Substrate channeling in proline metabolism

    PubMed Central

    Arentson, Benjamin W.; Sanyal, Nikhilesh; Becker, Donald F.

    2012-01-01

    Proline metabolism is an important pathway that has relevance in several cellular functions such as redox balance, apoptosis, and cell survival. Results from different groups have indicated that substrate channeling of proline metabolic intermediates may be a critical mechanism. One intermediate is pyrroline-5-carboxylate (P5C), which upon hydrolysis opens to glutamic semialdehyde (GSA). Recent structural and kinetic evidence indicate substrate channeling of P5C/GSA occurs in the proline catabolic pathway between the proline dehydrogenase and P5C dehydrogenase active sites of bifunctional proline utilization A (PutA). Substrate channeling in PutA is proposed to facilitate the hydrolysis of P5C to GSA which is unfavorable at physiological pH. The second intermediate, gamma-glutamyl phosphate, is part of the proline biosynthetic pathway and is extremely labile. Substrate channeling of gamma-glutamyl phosphate is thought to be necessary to protect it from bulk solvent. Because of the unfavorable equilibrium of P5C/GSA and the reactivity of gamma-glutamyl phosphate, substrate channeling likely improves the efficiency of proline metabolism. Here, we outline general strategies for testing substrate channeling and review the evidence for channeling in proline metabolism. PMID:22201749

  9. Video Event Trigger

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.; Lichter, Michael J.

    1994-01-01

    Video event trigger (VET) processes video image data to generate trigger signal when image shows significant change like motion or appearance, disappearance, change in color, change in brightness, or dilation of object. System aids in efficient utilization of image-data-storage and image-data-processing equipment in applications in which many video frames show no changes and are wasteful to record and analyze all frames when only relatively few frames show changes of interest. Applications include video recording of automobile crash tests, automated video monitoring of entrances, exits, parking lots, and secure areas.

  10. Presidential Events: Chicago

    NASA Astrophysics Data System (ADS)

    Walworth, Frank

    2007-03-01

    Catherine T. ("Katie") Hunt, ACS President 2007, will cosponsor a full week of presidential events and sessions. In her desire to work together to address substantive societal issues, she has selected Sustainability of Energy, Food, and Water as the presidential theme for this meeting. The goal is to successfully execute meaningful thematic programming at national meetings that will not only nucleate ideas, foster community, and accelerate innovation, but be essential to effectively communicate chemistry to a broader audience. Open discussions as a scientific community will better enable us to speak with one voice to our membership, the media, and the general public.

  11. Detection of solar events

    DOEpatents

    Fischbach, Ephraim; Jenkins, Jere

    2013-08-27

    A flux detection apparatus can include a radioactive sample having a decay rate capable of changing in response to interaction with a first particle or a field, and a detector associated with the radioactive sample. The detector is responsive to a second particle or radiation formed by decay of the radioactive sample. The rate of decay of the radioactive sample can be correlated to flux of the first particle or the field. Detection of the first particle or the field can provide an early warning for an impending solar event.

  12. Vaccine adverse events.

    PubMed

    Follows, Jill

    2012-01-01

    Millions of adults are vaccinated annually against the seasonal influenza virus. An undetermined number of individuals will develop adverse events to the influenza vaccination. Those who suffer substantiated vaccine injuries, disabilities, and aggravated conditions may file a timely, no-fault and no-cost petition for financial compensation under the National Vaccine Act in the Vaccine Court. The elements of a successful vaccine injury claim are described in the context of a claim showing the seasonal influenza vaccination was the cause of Guillain-Barré syndrome.

  13. [Adverse events prevention ability].

    PubMed

    Aparo, Ugo Luigi; Aparo, Andrea

    2007-03-01

    The issue of how to address medical errors is the key to improve the health care system performances. Operational evidence collected in the last five years shows that the solution is only partially linked to future technological developments. Cultural and organisational changes are mandatory to help to manage and drastically reduce the adverse events in health care organisations. Classical management, merely based on coordination and control, is inadequate. Proactive, self-organising network based structures must be put in place and managed using adaptive, fast evolving management tools. PMID:17484160

  14. [Adverse events prevention ability].

    PubMed

    Aparo, Ugo Luigi; Aparo, Andrea

    2007-03-01

    The issue of how to address medical errors is the key to improve the health care system performances. Operational evidence collected in the last five years shows that the solution is only partially linked to future technological developments. Cultural and organisational changes are mandatory to help to manage and drastically reduce the adverse events in health care organisations. Classical management, merely based on coordination and control, is inadequate. Proactive, self-organising network based structures must be put in place and managed using adaptive, fast evolving management tools.

  15. Convergence of ion channel genome content in early animal evolution

    PubMed Central

    Liebeskind, Benjamin J.; Hillis, David M.; Zakon, Harold H.

    2015-01-01

    Multicellularity has evolved multiple times, but animals are the only multicellular lineage with nervous systems. This fact implies that the origin of nervous systems was an unlikely event, yet recent comparisons among extant taxa suggest that animal nervous systems may have evolved multiple times independently. Here, we use ancestral gene content reconstruction to track the timing of gene family expansions for the major families of ion-channel proteins that drive nervous system function. We find that animals with nervous systems have broadly similar complements of ion-channel types but that these complements likely evolved independently. We also find that ion-channel gene family evolution has included large loss events, two of which were immediately followed by rounds of duplication. Ctenophores, cnidarians, and bilaterians underwent independent bouts of gene expansion in channel families involved in synaptic transmission and action potential shaping. We suggest that expansions of these family types may represent a genomic signature of expanding nervous system complexity. Ancestral nodes in which nervous systems are currently hypothesized to have originated did not experience large expansions, making it difficult to distinguish among competing hypotheses of nervous system origins and suggesting that the origin of nerves was not attended by an immediate burst of complexity. Rather, the evolution of nervous system complexity appears to resemble a slow fuse in stem animals followed by many independent bouts of gene gain and loss. PMID:25675537

  16. Channel responses to varying sediment input: A flume experiment modeled after Redwood Creek, California

    USGS Publications Warehouse

    Madej, M.A.; Sutherland, D.G.; Lisle, T.E.; Pryor, B.

    2009-01-01

    At the reach scale, a channel adjusts to sediment supply and flow through mutual interactions among channel form, bed particle size, and flow dynamics that govern river bed mobility. Sediment can impair the beneficial uses of a river, but the timescales for studying recovery following high sediment loading in the field setting make flume experiments appealing. We use a flume experiment, coupled with field measurements in a gravel-bed river, to explore sediment transport, storage, and mobility relations under various sediment supply conditions. Our flume experiment modeled adjustments of channel morphology, slope, and armoring in a gravel-bed channel. Under moderate sediment increases, channel bed elevation increased and sediment output increased, but channel planform remained similar to pre-feed conditions. During the following degradational cycle, most of the excess sediment was evacuated from the flume and the bed became armored. Under high sediment feed, channel bed elevation increased, the bed became smoother, mid-channel bars and bedload sheets formed, and water surface slope increased. Concurrently, output increased and became more poorly sorted. During the last degradational cycle, the channel became armored and channel incision ceased before all excess sediment was removed. Selective transport of finer material was evident throughout the aggradational cycles and became more pronounced during degradational cycles as the bed became armored. Our flume results of changes in bed elevation, sediment storage, channel morphology, and bed texture parallel those from field surveys of Redwood Creek, northern California, which has exhibited channel bed degradation for 30??years following a large aggradation event in the 1970s. The flume experiment suggested that channel recovery in terms of reestablishing a specific morphology may not occur, but the channel may return to a state of balancing sediment supply and transport capacity.

  17. On the origin of closing flickers in gramicidin channels: a new hypothesis.

    PubMed

    Armstrong, Kathryn M; Cukierman, Samuel

    2002-03-01

    The submillisecond closing events (flickers) and the single channel conductances to protons (g(H)) were studied in native gramicidin A (gA) and in the SS and RR diastereoisomers of dioxolane-linked gA channels in planar bilayers. Bilayers were formed from glycerylmonooleate (GMO) in various solvents. In GMO/decane (thick) bilayers, the largest flicker frequency occurred in the SS channel (39 s(-1)), followed by the RR (4 s(-1)) and native gA channels (3 s(-1)). These frequencies were attenuated in GMO/squalene (thin) bilayers by 100-, 30-, and 70-fold in the SS, RR, and native gA channels, respectively. In thin bilayers, the average burst duration of native gA channels was 30-fold longer than in thick bilayers. The RR dioxolane-linked gA dimer "inactivated" in GMO/decane but not in squalene-containing bilayers. The mean closed time of flickers (approximately 0.12 ms) was essentially the same in various gA channels. In thin bilayers, g(H) values were larger by approximately 10% (SS), 30% (RR), and 20% (native gA) in relation to thick bilayers. It is concluded that flickers are not related to pre-dissociation or dissociation states of gA monomers, and do not seem to be caused by intrinsic conformational changes of channel proteins. It is proposed that flickers are caused by undulations of the bilayer that obliterate the openings of gA channels. Differences between flicker frequencies in various gA channels are likely to result from variations in channel geometries at the bilayer/channel interface. The smaller g(H) in thick bilayers suggests that the deformation of these bilayers around the gA channel creates a diffusional pathway next to the mouths of the channel that is longer and more restrictive than in thin GMO bilayers. A possible molecular interpretation for these effects is attempted.

  18. Resurfacing history of the Harmakhis Vallis channel, Mars

    NASA Astrophysics Data System (ADS)

    Kukkonen, Soile; Kostama, Veli-Petri

    2016-10-01

    Harmakhis Vallis is one of the four major outflow channel systems (Dao, Niger, Harmakhis and Reull Valles) which cut the eastern rim region of the Hellas basin, the largest well-preserved impact structure of Mars. The structure of Harmakhis Vallis and the volume of its head depression, as well as the earlier dating studies suggest that the channel formed during the Hesperian period by collapsing when a large amount of subsurface fluids was released. Thus Harmakhis Vallis, as well as the other nearby outflow channels, represent a significant stage of the fluvial activity in the regional history. On the other hand, the channel lies on the Martian mid-latitude zone, where there are several geomorphologic indicators of past and possibly also contemporary ground ice. The floor of Harmakhis also displays evidence of a later-stage ice-related activity as the channel has been covered by lineated valley fill deposits and debris apron material.The eastern rim region of the Hellas impact basin has been the subject of numerous geologic mapping studies at various scales and using different imaging data sets. However, the Harmakhis Vallis channel itself has received less attention, or the studies on the channel have focused only on different geologic events as a separate subject. In this work, we present our mapping and dating results of the Harmakhis Vallis floor based on the Mars Reconnaissance Orbiter's ConTeX camera imagery (CTX; ~5 m/pixel), which covers the entire Harmakhis channel system from its head depression to the beginning of the terminus. The purpose of the study is to outline how the floor of the Harmakhis Vallis channel has been modified after its formation, what kind of geologic processes have occurred on the channel and when, and by doing so, provide further understanding of the channel evolution and changes in the Martian climate. This work also gives information about the crater counting age determination method and its usability in the cases where only high

  19. Marine Toxins Targeting Ion Channels

    PubMed Central

    Arias, Hugo R.

    2006-01-01

    This introductory minireview points out the importance of ion channels for cell communication. The basic concepts on the structure and function of ion channels triggered by membrane voltage changes, the so-called voltage-gated ion channels (VGICs), as well as those activated by neurotransmitters, the so-called ligand-gated ion channel (LGICs), are introduced. Among the most important VGIC superfamiles, we can name the voltage-gated Na+ (NaV), Ca2+ (CaV), and K+ (KV) channels. Among the most important LGIC super families, we can include the Cys-loop or nicotinicoid, the glutamate-activated (GluR), and the ATP-activated (P2XnR) receptor superfamilies. Ion channels are transmembrane proteins that allow the passage of different ions in a specific or unspecific manner. For instance, the activation of NaV, CaV, or KV channels opens a pore that is specific for Na+, Ca2+, or K+, respectively. On the other hand, the activation of certain LGICs such as nicotinic acetylcholine receptors, GluRs, and P2XnRs allows the passage of cations (e.g., Na+, K+, and/or Ca2+), whereas the activation of other LGICs such as type A γ-butyric acid and glycine receptors allows the passage of anions (e.g., Cl− and/or HCO3−). In this regard, the activation of NaV and CaV as well as ligand-gated cation channels produce membrane depolarization, which finally leads to stimulatory effects in the cell, whereas the activation of KV as well as ligand-gated anion channels induce membrane hyperpolarization that finally leads to inhibitory effects in the cell. The importance of these ion channel superfamilies is emphasized by considering their physiological functions throughout the body as well as their pathophysiological implicance in several neuronal diseases. In this regard, natural molecules, and especially marine toxins, can be potentially used as modulators (e.g., inhibitors or prolongers) of ion channel functions to treat or to alleviate a specific ion channel-linked disease (e

  20. Differences between Formal and Informal Communicative Channels.

    ERIC Educational Resources Information Center

    Johnson, J. David; And Others

    1994-01-01

    Compares formal and informal organizational communication structures within a large, technically oriented midwestern state governmental agency, specifically focusing on salience, channel factors, and channel usage. Suggests that informal channels in this organization were more highly evaluated in general. (SR)

  1. 33 CFR 117.966 - Galveston Channel.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Texas § 117.966 Galveston Channel. Link to an... across Galveston Channel, mile 4.5 of the Galveston Channel, (GIWW mile 356.1) at Galveston, Texas,...

  2. Relativistic tidal disruption events

    NASA Astrophysics Data System (ADS)

    Levan, A.

    2012-12-01

    In March 2011 Swift detected an extremely luminous and long-lived outburst from the nucleus of an otherwise quiescent, low luminosity (LMC-like) galaxy. Named Swift J1644+57, its combination of high-energy luminosity (1048 ergs s-1 at peak), rapid X-ray variability (factors of >100 on timescales of 100 seconds) and luminous, rising radio emission suggested that we were witnessing the birth of a moderately relativistic jet (Γ ˜ 2 - 5), created when a star is tidally disrupted by the supermassive black hole in the centre of the galaxy. A second event, Swift J2058+0516, detected two months later, with broadly similar properties lends further weight to this interpretation. Taken together this suggests that a fraction of tidal disruption events do indeed create relativistic outflows, demonstrates their detectability, and also implies that low mass galaxies can host massive black holes. Here, I briefly outline the observational properties of these relativistic tidal flares observed last year, and their evolution over the first year since their discovery.

  3. Nutrition for distance events.

    PubMed

    Burke, Louise M; Millet, Gregoire; Tarnopolsky, Mark A

    2007-01-01

    The goal of training is to prepare the distance athlete to perform at his or her best during major competitions. Whatever the event, nutrition plays a major role in the achievement of various factors that will see a runner or walker take the starting line in the best possible form. Everyday eating patterns must supply fuel and nutrients needed to optimize their performance during training sessions and to recover quickly afterwards. Carbohydrate and fluid intake before, during, and after a workout may help to reduce fatigue and enhance performance. Recovery eating should also consider issues for adaptation and the immune system that may involve intakes of protein and some micronutrients. Race preparation strategies should include preparation of adequate fuel stores, including carbohydrate loading for prolonged events such as the marathon or 50-km walk. Fluid and carbohydrate intake during races lasting an hour or more should also be considered. Sports foods and supplements of value to distance athletes include sports drinks and liquid meal supplements to allow nutrition goals to be achieved when normal foods are not practical. While caffeine is an ergogenic aid of possible value to distance athletes, most other supplements are of minimal benefit. PMID:18049981

  4. Screening for adverse events.

    PubMed

    Karson, A S; Bates, D W

    1999-02-01

    Adverse events (AEs) in medical patients are common, costly, and often preventable. Development of quality improvement programs to decrease the number and impact of AEs demands effective methods for screening for AEs on a routine basis. Here we describe the impact, types, and potential causes of AEs and review various techniques for identifying AEs. We evaluate the use of generic screening criteria in detail and describe a recent study of the sensitivity and specificity of individual generic screening criteria and combinations of these criteria. In general, the most sensitive screens were the least specific and no small sub-set of screens identified a large percentage of adverse events. Combinations of screens that were limited to administrative data were the least expensive, but none were particularly sensitive, although in practice they might be effective since routine screening is currently rarely done. As computer systems increase in sophistication sensitivity will improve. We also discuss recent studies that suggest that programs that screen for and identify AEs can be useful in reducing AE rates. While tools for identifying AEs have strengths and weaknesses, they can play an important role in organizations' quality improvement portfolios. PMID:10468381

  5. Infrasound Event Analysis into the IDC Operations

    NASA Astrophysics Data System (ADS)

    Mialle, Pierrick; Bittner, Paulina; Brachet, Nicolas; Brown, David; Given, Jeffrey; Le Bras, Ronan; Coyne, John

    2010-05-01

    The first atmospheric event built only from infrasound arrivals was reported in the Reviewed Event Bulletin (REB) of the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) in 2003. In the last decade, 42 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The growing amount of infrasound data and detections produced by the automatic system challenged the station and network processing at the IDC, which required the Organization to redesign the way infrasound data are processed. Each infrasound array is processed separately for signal detection using a progressive multi-channel correlation method (DFX-PMCC). For each detection, signal features - onset time, amplitude, frequency, duration, azimuth, phase velocity, F-statistics - are measured and used to identify a detection as infrasonic, seismic, or noise (including clutter). Infrasonic signals along with seismic and hydroacoustic signals are subsequently associated with Global Association software (GA) between stations to locate events. During detection and association phases, criteria are applied to eliminate clutter, identify signals of interest, and keep the number of automatic events containing infrasound detections to a manageable level for analyst review. The IDC has developed analysis and visualization tools specifically for infrasound review (e.g. Geotool-PMCC). The IDC has continued to build the Infrasound Reference Event Database (IRED) from observations on the IMS network. This database assists both the routine IDC infrasound analysis and analyst training as it reflects the global detection capability of the network, illustrates the spatial and temporal variability of the observed phenomena, and demonstrates the various origins of infragenic sources. Since 2007, the IDC has introduced new analyst procedures to review and add selected infrasound events to the REB. In early 2010, the IDC

  6. A study of eruptive solar events with negative radio bursts

    NASA Astrophysics Data System (ADS)

    Kuz'menko, I. V.; Grechnev, V. V.; Uralov, A. M.

    2009-11-01

    Solar events of June 15/16, 2000, June 1/2, 2002, February 6, 2002, and February 7, 2002, have been studied. These events probably belong to a poorly studied class of explosive eruptions. In such events disintegration of the magnetic structure of an eruptive filament and dispersing of its fragments as a cloud over a considerable part of the solar surface are possible. The analysis of SOHO/EIT extreme ultraviolet images obtained in the 195 Å and 304 Å channels has revealed the appearance of dimmings of various shapes and propagation of a coronal wave for June 1/2, 2002. In all the events the Nobeyama, Learmonth, and Ussuriysk observatories recorded negative radio bursts at several frequencies in the 1-10 GHz range. Most likely, these bursts were due to absorption of solar radio emission in clouds produced by fragments of filaments. Absorption of the solar background radiation can be observed as a depression of the emission in the 304 Å channel. A model has been developed, which permits one to estimate parameters of absorbing plasma such as temperature, optical thickness, area of the absorbing cloud, and its height above the chromosphere from the radio absorption observed at several frequencies. The obtained values of the temperature, 8000-9000 K, demonstrate that the absorber was the material of an erupted cool filament. The model estimate of the masses of the ejecta in the considered events were ˜1015 g, which is comparable to masses of typical filaments and coronal mass ejections.

  7. Infinitely many kinds of quantum channels

    SciTech Connect

    Hastings, Matthew B

    2008-01-01

    We define the ability of a quantum channel to simulate another by means of suitable encoding and decoding operations. While classical channels have only two equivalence classes under simulation (channels with non-vanishing capacity and those with vanishing capacity), we show that there are an uncountable infinity of different equivalence classes of quantum channels using the example of the quantum erasure channel. Our results also imply a kind of 'Matthew principle' for error correction on certain channels.

  8. Thermosyphon boiling in vertical channels

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, A.; Schweitzer, H.

    The thermal characteristics of ebullient cooling systems for VHSIC and VLSI microelectronic component thermal control are studied by experimentally and analytically investigating boiling heat transfer from a pair of flat, closely spaced, isoflux plates immersed in saturated water. A theoretical model for liquid flow rate through the channel is developed and used as a basis for correlating the rate of heat transfer from the channel walls. Experimental results for wall temperature as a function of axial location, heat flux, and plate spacing are presented. The finding that the wall superheat at constant imposed heat flux decreases as the channel is narrowed is explained with the aid of a boiling thermosiphon analysis which yields the mass flux through the channel.

  9. Structural Biology of TRP Channels

    PubMed Central

    Hellmich, Ute A.; Gaudet, Rachelle

    2016-01-01

    Membrane proteins remain challenging targets for structural biologists, despite recent technical developments regarding sample preparation and structure determination. We review recent progress towards a structural understanding of TRP channels and the techniques used to that end. We discuss available low-resolution structures from electron microscopy (EM), X-ray crystallography and nuclear magnetic resonance (NMR), and review the resulting insights into TRP channel function for various subfamily members. The recent high-resolution structure of TRPV1 is discussed in more detail in Chapter X. We also consider the opportunities and challenges of using the accumulating structural information on TRPs and homologous proteins for deducing full-length structures of different TRP channel subfamilies, such as building homology models. Finally, we close by summarizing the outlook of the “holy grail” of understanding in atomic detail the diverse functions of TRP channels. PMID:24961976

  10. Aquaglyceroporins: ancient channels for metalloids.

    PubMed

    Bhattacharjee, Hiranmoy; Mukhopadhyay, Rita; Thiyagarajan, Saravanamuthu; Rosen, Barry P

    2008-11-07

    The identification of aquaglyceroporins as uptake channels for arsenic and antimony shows how these toxic elements can enter the food chain, and suggests that food plants could be genetically modified to exclude arsenic while still accumulating boron and silicon.

  11. Ion Channels in Nerve Membranes

    ERIC Educational Resources Information Center

    Ehrenstein, Gerald

    1976-01-01

    Discusses research that indicates that nerve membranes, which play a key role in the conduction of impulses, are traversed by protein channels with ion pathways opened and closed by the membrane electric field. (Author/MLH)

  12. FAITH Water Channel Flow Visualization

    NASA Video Gallery

    Water channel flow visualization experiments are performed on a three dimensional model of a small hill. This experiment was part of a series of measurements of the complex fluid flow around the hi...

  13. Catalytic reaction in confined flow channel

    DOEpatents

    Van Hassel, Bart A.

    2016-03-29

    A chemical reactor comprises a flow channel, a source, and a destination. The flow channel is configured to house at least one catalytic reaction converting at least a portion of a first nanofluid entering the channel into a second nanofluid exiting the channel. The flow channel includes at least one turbulating flow channel element disposed axially along at least a portion of the flow channel. A plurality of catalytic nanoparticles is dispersed in the first nanofluid and configured to catalytically react the at least one first chemical reactant into the at least one second chemical reaction product in the flow channel.

  14. The design of trellis codes for fading channels

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Simon, Marvin K.

    1987-01-01

    The appropriate criterion for optimum trellis coded modulation design on the additive white Gaussian noise channel is maximization of the free Euclidean distance. When trellis coded modulation is used on a Rician fading channel with interleaving/deinterleaving, the design of the code for optimum performance is guided by other factors, in particular the length of the shortest error event path, and the product of branch distances (possibly normalized by the Euclidean distance of the path) along that path. Although maximum free distance (d sub free) is still an important consideration, it plays a less significant role the more severe the fading is on the channel. These considerations lead to the definition of a new distance measure for optimization of trellis codes transmitted over Rician fading channels. If no interleaving/deinterleaving is used, then once again the design of the trellis code is guided by maximizing d sub free. It is also shown that allowing for multiple symbols per trellis branch, i.e., multiple trellis coded modulation (MTCM), provides an additional degree of freedom for designing a code to meet the above optimization criteria on the fading channel. It is here where the MTCM technique exploits its full potential.

  15. Estimating aquifer channel recharge using optical data interpretation.

    PubMed

    Walter, Gary R; Necsoiu, Marius; McGinnis, Ronald

    2012-01-01

    Recharge through intermittent and ephemeral stream channels is believed to be a primary aquifer recharge process in arid and semiarid environments. The intermittent nature of precipitation and flow events in these channels, and their often remote locations, makes direct flow and loss measurements difficult and expensive. Airborne and satellite optical images were interpreted to evaluate aquifer recharge due to stream losses on the Frio River in south-central Texas. Losses in the Frio River are believed to be a major contributor of recharge to the Edwards Aquifer. The results of this work indicate that interpretation of readily available remote sensing optical images can offer important insights into the spatial distribution of aquifer recharge from losing streams. In cases where upstream gauging data are available, simple visual analysis of the length of the flowing reach downstream from the gauging station can be used to estimate channel losses. In the case of the Frio River, the rate of channel loss estimated from the length of the flowing reach at low flows was about half of the loss rate calculated from in-stream gain-loss measurements. Analysis based on water-surface width and channel slope indicated that losses were mainly in a reach downstream of the mapped recharge zone. The analysis based on water-surface width, however, did not indicate that this method could yield accurate estimates of actual flow in pool and riffle streams, such as the Frio River and similar rivers draining the Edwards Plateau.

  16. Ion channel screening technologies today.

    PubMed

    Terstappen, Georg C

    2005-01-01

    For every heartbeat, movement and thought, ion channels have to open and close, and thus, it is not surprising that malfunctioning of these membrane proteins leads to serious diseases. Today, only 7% of all marketed drugs act on ion channels but the systematic exploitation of this important target class has started mainly enabled by novel screening technologies. Thus, the discovery of selective and state-dependent drugs is on the horizon, hopefully leading to effective novel medicines.:

  17. Comments on event driven animation

    NASA Technical Reports Server (NTRS)

    Gomez, Julian E.

    1987-01-01

    Event driven animation provides a general method of describing controlling values for various computer animation techniques. A definition and comments are provided on genralizing motion description with events. Additional comments are also provided about the implementation of twixt.

  18. Integrating unseen events over time.

    PubMed

    Reber, Thomas P; Henke, Katharina

    2012-06-01

    Events often share elements that guide us to integrate knowledge from these events. Integration allows us to make inferences that affect reactions to new events. Integrating events and making inferences are thought to depend on consciousness. We show that even unconsciously experienced events, that share elements, are integrated and influence reactions to new events. An unconscious event consisted of the subliminal presentation of two unrelated words. Half of subliminal word pairs shared one word ('winter red', 'red computer'). Overlapping word pairs were presented between 6s and 78 s apart. The test for integration required participants to judge the semantic distance between suprathreshold words ('winter computer'). Evidence of integration was provided by faster reactions to suprathreshold words that were indirectly related versus unrelated. This effect was independent of the time interval between overlapping word pairs. We conclude that consciousness is no requirement for the integration of discontiguous events.

  19. Cells anticipate periodic events

    NASA Astrophysics Data System (ADS)

    Nakagaki, Toshiyuki

    2009-03-01

    We show that an amoeboid organism can anticipate the timing of periodic events. The plasmodium of the true slime mold Physarum polycephalum moves rapidly under favourable conditions, but stops moving when transferred to less-favourable conditions. Plasmodia exposed to unfavourable conditions, presented in three consecutive pulses at constant intervals, reduced their locomotive speed in response to each episode. When subsequently subjected to favourable conditions, the plasmodia spontaneously reduced their locomotive speed at the time point when the next unfavourable episode would have occurred. This implied anticipation of impending environmental change. After this behaviour had been evoked several times, the locomotion of the plasmodia returned to normal; however, the anticipatory response could subsequently be induced by a single unfavourable pulse, implying recall of the memorized periodicity. We explored the mechanisms underlying these behaviours from a dynamical systems perspective. Our results hint at the cellular origins of primitive intelligence and imply that simple dynamics might be sufficient to explain its emergence.

  20. Event counting alpha detector

    DOEpatents

    Bolton, R.D.; MacArthur, D.W.

    1996-08-27

    An electrostatic detector is disclosed for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure. 6 figs.

  1. Event counting alpha detector

    DOEpatents

    Bolton, Richard D.; MacArthur, Duncan W.

    1996-01-01

    An electrostatic detector for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure.

  2. Intracellular calcium channels in protozoa.

    PubMed

    Docampo, Roberto; Moreno, Silvia N J; Plattner, Helmut

    2014-09-15

    Ca(2+)-signaling pathways and intracellular Ca(2+) channels are present in protozoa. Ancient origin of inositol 1,4,5-trisphosphate receptors (IP3Rs) and other intracellular channels predates the divergence of animals and fungi as evidenced by their presence in the choanoflagellate Monosiga brevicollis, the closest known relative to metazoans. The first protozoan IP3R cloned, from the ciliate Paramecium, displays strong sequence similarity to the rat type 3 IP3R. This ciliate has a large number of IP3- and ryanodine(Ry)-like receptors in six subfamilies suggesting the evolutionary adaptation to local requirements for an expanding diversification of vesicle trafficking. IP3Rs have also been functionally characterized in trypanosomatids, where they are essential for growth, differentiation, and establishment of infection. The presence of the mitochondrial calcium uniporter (MCU) in a number of protozoa indicates that mitochondrial regulation of Ca(2+) signaling is also an early appearance in evolution, and contributed to the discovery of the molecular nature of this channel in mammalian cells. There is only sequence evidence for the occurrence of two-pore channels (TPCs), transient receptor potential Ca(2+) channels (TRPCs) and intracellular mechanosensitive Ca(2+)-channels in Paramecium and in parasitic protozoa.

  3. Channelized Optical Waveguides On Silicon

    NASA Astrophysics Data System (ADS)

    Hickernell, F. S.; Seaton, C. T.

    1987-02-01

    Silicon provides a natural substrate base for the development of channel waveguides and their integration with optoelectronic components. Using epitaxial growth, selective doping, and plasma etching, channel waveguides can be fabricated using single crystal silicon alone. Oxide layers of low optical index are readily formed by thermal means on silicon to provide a base upon which low-loss film waveguides can be formed by ion exchange and implantation, chemical vapor deposition, and physical vapor deposition. Thermally oxidized and nitrided layers provide a simple means for developing waveguides. The channel shape for ridge waveguides can be delineated by chemical etching and ion milling techniques. The anisotropic etch characteristics of silicon provide a natural channel for imbedding waveguides using organic and inorganic materials. This paper will review common semiconductor processing techniques used for the formation of channel waveguides on silicon and the performance results obtained to date. The use of channel waveguides for specific device developments will be described and the most promising areas for future development will be addressed.

  4. Intracellular Calcium Channels in Protozoa

    PubMed Central

    Docampo, Roberto; Moreno, Silvia N.J.; Plattner, Helmut

    2014-01-01

    Ca2+-signaling pathways and intracellular Ca2+ channels are present in protozoa. Ancient origin of inositol 1,4,5-trisphosphate receptors (IP3Rs) and other intracellular channels predates the divergence of animals and fungi as evidenced by their presence in the choanoflagellate Monosiga brevicollis, the closest known relative to metazoans. The first protozoan IP3R cloned, from the ciliate Paramecium, displays strong sequence similarity to the rat type 3 IP3R. This ciliate has a large number of IP3- and ryanodine(Ry)-like receptors in 6 subfamilies suggesting the evolutionary adaptation to local requirements for an expanding diversification of vesicle trafficking. IP3Rs have also been functionally characterized in trypanosomatids, where they are essential for growth, differentiation, and establishment of infection. The presence of the mitochondrial calcium uniporter (MCU) in a number of protozoa indicates that mitochondrial regulation of Ca2+ signaling is also an early appearance in evolution, and contributed to the discovery of the molecular nature of this channel in mammalian cells. There is only sequence evidence for the occurrence of two-pore channels (TPCs), transient receptor potential Ca2+ channels (TRPCs) and intracellular mechanosensitive Ca2+-channels in Paramecium and in parasitic protozoa. PMID:24291099

  5. A three channel telemetry system

    NASA Technical Reports Server (NTRS)

    Lesho, Jeffery C.; Eaton, Harry A. C.

    1993-01-01

    A three channel telemetry system intended for biomedical applications is described. The transmitter is implemented in a single chip using a 2 micron BiCMOS processes. The operation of the system and the test results from the latest chip are discussed. One channel is always dedicated to temperature measurement while the other two channels are generic. The generic channels carry information from transducers that are interfaced to the system through on-chip general purpose operational amplifiers. The generic channels have different bandwidths: one from dc to 250 Hz and the other from dc to 1300 Hz. Each generic channel modulates a current controlled oscillator to produce a frequency modulated signal. The two frequency modulated signals are summed and used to amplitude modulate the temperature signal which acts as a carrier. A near-field inductive link telemeters the combined signals over a short distance. The chip operates on a supply voltage anywhere from 2.5 to 3.6 Volts and draws less than 1 mA when transmitting a signal. The chip can be incorporated into ingestible, implantable and other configurations. The device can free the patient from tethered data collection systems and reduces the possibility of infection from subcutaneous leads. Data telemetry can increase patient comfort leading to a greater acceptance of monitoring.

  6. High resolution imaging of the outflow channels on Mars

    NASA Astrophysics Data System (ADS)

    Davatzes, A. K.; Gulick, V. C.

    2008-12-01

    We report observations of the outflow channels on Mars from HiRISE images in MRO's first Martian year. Several hundred images of the outflow channels on Mars have been collected to date from HiRISE, as well as coordinated images with CTX and CRISM. Depositional features, such as slackwater deposits and small bedforms that are expected to be visible at the resolution of HiRISE have not yet been observed, largely due to post-fluvial modification of the channels. Many of the channels have been subsequently covered by a thin layer of lava, ash, dust, or lineated valley fill. Although altered slightly by later aeolian modification, Ares Valles and Kasei Valles preserve much of the original fluvial erosional forms, particularly cataracts and longitudinal grooves that can be used to infer the mechanics of the flow. Cataracts, steep knickpoints in the large outflow channels, were once large waterfalls on the Martian surface. These have been observed in all of the larger outflow systems, including Kasai, Athabasca, Mangala, and Reull Valles. High resolution imaging shows that all of the cataract systems have multiple generations of erosion, with smaller subchannels within the cataract system. Based on the length of the recession and the morphological evidence most of the large channels experienced multiple flooding events or pulses. The tectonically sourced outflow channels, such as Athabasca and Mangala Valles, show sourcing at regions of complex fault geometries, specifically at fault relays. In terrestrial systems, relays tend to be regions of concentrated stress that can produce dilation manifested as high joint density, as well as point sources for hydrothermal outflow on Earth. Athabasca and Mangala Valles, sourced proximal to large volcanic centers, may have been regions of major hydrothermal activity in the past.

  7. Coordination of epigenetic events.

    PubMed

    El-Osta, A

    2004-09-01

    During the course of DNA damage a complex repertoire of molecular signals, chromatin determinants and specific transcription factors are set in motion for repair. In many instances, the response pathway can be characterized by profound changes in molecular remodeling and is intimately linked with DNA replication and gene transcription. Our understanding of the molecular pathways has come from scientific developments that represent many disparate disciplines, such as cancer (epi)genetics, chromatin modifications during cellular development and the emerging prominence of epigenetic events in human disease. These multidisciplinary areas reveal a functional relationship and suggest that repair and transcription must coincide in the context of chromatin. We have come to appreciate the repair process and the role of transcriptional components in a sophisticated program of epigenetic regulation, and we have learnt much since the first description of the nucleosome as a spheroid disklike unit. The coordinated and ordered response to DNA damage can specify structures that mobilize and remodel nucleosomes. Investigators will undoubtedly continue to explore the structural and functional states of DNA damage repair and continue to profile the sequence of events and scrutinize the molecular signatures that specify these changes in chromatin dynamics, genomic stability and transcriptional performance. In this special issue, authors have contributed reviews that discuss hypotheses and results regarding DNA damage repair and transcription. The topics covered range from DNA repair in a chromatin environment to the deadly double-strand break, histone modifications to ATP-dependent chromatin remodeling, gene silencing in cancer to apoptosis and regulation of chromatin dynamics by DNA methylation. The scene is set for a new view of damage detection and repair by the coordination of epigenetic states.

  8. Sudden Event Recognition: A Survey

    PubMed Central

    Suriani, Nor Surayahani; Hussain, Aini; Zulkifley, Mohd Asyraf

    2013-01-01

    Event recognition is one of the most active research areas in video surveillance fields. Advancement in event recognition systems mainly aims to provide convenience, safety and an efficient lifestyle for humanity. A precise, accurate and robust approach is necessary to enable event recognition systems to respond to sudden changes in various uncontrolled environments, such as the case of an emergency, physical threat and a fire or bomb alert. The performance of sudden event recognition systems depends heavily on the accuracy of low level processing, like detection, recognition, tracking and machine learning algorithms. This survey aims to detect and characterize a sudden event, which is a subset of an abnormal event in several video surveillance applications. This paper discusses the following in detail: (1) the importance of a sudden event over a general anomalous event; (2) frameworks used in sudden event recognition; (3) the requirements and comparative studies of a sudden event recognition system and (4) various decision-making approaches for sudden event recognition. The advantages and drawbacks of using 3D images from multiple cameras for real-time application are also discussed. The paper concludes with suggestions for future research directions in sudden event recognition. PMID:23921828

  9. Event boundaries and memory improvement.

    PubMed

    Pettijohn, Kyle A; Thompson, Alexis N; Tamplin, Andrea K; Krawietz, Sabine A; Radvansky, Gabriel A

    2016-03-01

    The structure of events can influence later memory for information that is embedded in them, with evidence indicating that event boundaries can both impair and enhance memory. The current study explored whether the presence of event boundaries during encoding can structure information to improve memory. In Experiment 1, memory for a list of words was tested in which event structure was manipulated by having participants walk through a doorway, or not, halfway through the word list. In Experiment 2, memory for lists of words was tested in which event structure was manipulated using computer windows. Finally, in Experiments 3 and 4, event structure was manipulated by having event shifts described in narrative texts. The consistent finding across all of these methods and materials was that memory was better when the information was distributed across two events rather than combined into a single event. Moreover, Experiment 4 demonstrated that increasing the number of event boundaries from one to two increased the memory benefit. These results are interpreted in the context of the Event Horizon Model of event cognition.

  10. The Teaching Events Stress Inventory.

    ERIC Educational Resources Information Center

    Cichon, Donald J.; Koff, Robert H.

    The Teaching Events Stress Inventory was designed to measure the degree of stress caused by thirty-six events associated with the teaching profession. The inventory was completed by 4,934 elementary and secondary school teachers employed by the Chicago Board of Education. Event one on the inventory, the first week of the school year, was given an…

  11. Temporal Profiles of SEP events

    NASA Astrophysics Data System (ADS)

    Gomez-Herrero, R.; del Peral, L.; Rodriguez-Frias, M. D.; Sequeiros, J.; Mueller-Mellin, R.; Kunow, H.

    2001-08-01

    This work is a preliminary study of 18 solar energetic particle (SEP) events detected by SOHO/EPHIN between 1996 and 2000. Temporal profiles of Impulsive and Gradual SEP events have been parameterized to determinate differences among SEP events depending on the magnetic connection and Physical conditions of the interplanetary transport.

  12. Stimuli, Reinforcers, and Private Events

    ERIC Educational Resources Information Center

    Nevin, John A.

    2008-01-01

    Radical behaviorism considers private events to be a part of ongoing observable behavior and to share the properties of public events. Although private events cannot be measured directly, their roles in overt action can be inferred from mathematical models that relate private responses to external stimuli and reinforcers according to the same…

  13. Dynamic Analysis of Event Histories.

    ERIC Educational Resources Information Center

    Tuma, Nancy Brandon; And Others

    1979-01-01

    Demonstrates the value of dynamic analysis of event-history data for the sociological study of change in categorical variables. An event history records dates of events that occur for some unit of analysis (i.e., an individual's marital or employment status, or outbreaks of riots or wars). (Author/AV)

  14. Event Structure and Cognitive Control

    ERIC Educational Resources Information Center

    Reimer, Jason F.; Radvansky, Gabriel A.; Lorsbach, Thomas C.; Armendarez, Joseph J.

    2015-01-01

    Recently, a great deal of research has demonstrated that although everyday experience is continuous in nature, it is parsed into separate events. The aim of the present study was to examine whether event structure can influence the effectiveness of cognitive control. Across 5 experiments we varied the structure of events within the AX-CPT by…

  15. Channel Forming Discharges and Scaling Relationships in Small Streams

    NASA Astrophysics Data System (ADS)

    Brayshaw, D. D.

    2008-12-01

    One of the major challenges in predicting or mitigating the impacts of disturbance on hydrologic systems is to link changes in hydrology to changes in sediment delivery and transport. Because of the complexity of modelling, usually only one system is considered in isolation, with any potential changes in the corresponding system inferred. For instance, a study of a small watershed might consider changes to peak flows or to sediment delivery to the channel, but not alteration in channel pattern caused by those changes. Linking our understanding of expected changes in hydrology and sediment transport is therefore important for improving land use management. In order to improve this understanding, the development of models and concepts linking hydrologic change to geomorphic change, and vice versa, is necessary. Channel and reach parameters (such as width, depth, slope, and channel pattern) reflect the adjustment of the stream channel to inputs of water, wood and sediment from upstream and upslope. Therefore, channel parameters can be used as indicators which synthesize the hydrologic and geomorphic processes occurring in a watershed (Goodwin et al, 1998). Two parameters which are particularly relevant are the bankfull discharge and the effective discharge. Bankfull discharge (Wolman and Leopold, 1957) is defined as the discharge at which the stream channel is full to the top of its banks, but not flooding over the bank. Effective discharge (Wolman and Miller, 1960) is defined as the discharge that, averaged over time, transports the most sediment. Estimating the frequency, magnitude, and duration of bankfull and effective discharge in a single stream reach provides an indication of the stream channel's stability and the frequency with which geomorphically effective events occur in the watershed upstream. Determining the bankfull and effective discharge for multiple streams across a region enables regionalization, consideration of scaling relationships, and evaluation

  16. Historic channel change on Esopus Creek, upstream of the Ashokan Reservoir, Catskills, New York

    NASA Astrophysics Data System (ADS)

    Miller, Nicolas Ross

    An understanding of historic channel change is fundamental to informing good stream management decisions. This study correlated the history of recent channel change on Esopus Creek in the Catskill Mountains of New York to patterns in the hydrologic record in order to understand the role of hydrologic controls on the stream's changing morphology. This study identified dynamic stream segments that have the potential to impact infrastructure and water quality in this watershed, which supplies a significant portion of New York City's drinking water. Changes in channel width, sinuosity, channel index and meander migration were obtained from quantitative analysis of aerial imagery from 1959, 1980 and 2001, along with historic topographic maps and field reconnaissance. Discharge patterns correlated with observed morphologic changes, while the role of other controlling variables such as basin and valley geography, climate, changing land use and historic channelization was explored. While there were no significant net changes in active channel width for the overall study period, overall channel width decreased between 1959 and 1980 and increased between 1980 and 2001. Reach-scale changes in channel width followed the same trend, with most reaches narrowing between 1959 and 1980 and widening between 1980 and 2001. The frequency and timing of large flow events were more significant in producing morphologic changes than the magnitude of a single event. The flood of record in 1980, which followed a 22-year hiatus in large flows, appears to have performed limited channel-width changes, while smaller magnitude but more frequent flows had much greater effects. Furthermore, time periods during which moderate flows, approximating bankfull conditions, occurred more frequently were correlated to periods of channel widening, whereas periods of less frequent moderate flows were correlated to periods of channel narrowing. Overall channel sinuosity did not change significantly over the

  17. Threshold hadronic event shapes with effective field theory

    SciTech Connect

    Kelley, Randall; Schwartz, Matthew D.

    2011-02-01

    Hadronic event shapes, that is, event shapes at hadron colliders, could provide a great way to test both standard and nonstandard theoretical models. However, they are significantly more complicated than event shapes at e{sup +}e{sup -} colliders, involving multiple hard directions, multiple channels, and multiple color structures. In this paper, hadronic event shapes are examined with soft-collinear effective theory (SCET) by expanding around the dijet limit. A simple event shape, threshold thrust, is defined. This observable is global and has no free parameters, making it ideal for clarifying how resummation of hadronic event shapes can be done in SCET. Threshold thrust is calculated at next-to-leading fixed order (NLO) in SCET and resummed to next-to-next-to-leading logarithmic (NNLL) accuracy. The scale-dependent parts of the soft function are shown to agree with what is expected from general observations, and the factorization formula is explicitly shown to be renormalization group invariant to 1-loop. Although threshold thrust is not itself expected to be phenomenologically interesting, it can be modified into a related observable which allows the jet p{sub T} distribution to be calculated and resummed to NNLL+NLO accuracy. As in other processes, one expects resummation to be important even for moderate jet momenta due to dynamical threshold enhancement. A general discussion of threshold enhancement and nonglobal logs in hadronic event shapes is also included.

  18. Sequential Reaction Channels of Metastable C{sup 4+}{sub 60}

    SciTech Connect

    Duenser, B.; Echt, O.; Scheier, P.; Maerk, T.D.

    1997-11-01

    We employ a two-sector-field mass spectrometer to identify sequential, unimolecular dissociation channels of C{sup 4+}{sub 60} . In addition to sequential {open_quotes}monomer evaporations{close_quotes} (loss of two C{sub 2} units), we observe two novel sequential channels which involve fissionlike events: loss of C{sup +}{sub 2} followed by evaporation, and sequential loss of two C{sup +}{sub 2} units. {copyright} {ital 1997} {ital The American Physical Society}

  19. EVENT PLANNING USING FUNCTION ANALYSIS

    SciTech Connect

    Lori Braase; Jodi Grgich

    2011-06-01

    Event planning is expensive and resource intensive. Function analysis provides a solid foundation for comprehensive event planning (e.g., workshops, conferences, symposiums, or meetings). It has been used at Idaho National Laboratory (INL) to successfully plan events and capture lessons learned, and played a significant role in the development and implementation of the “INL Guide for Hosting an Event.” Using a guide and a functional approach to planning utilizes resources more efficiently and reduces errors that could be distracting or detrimental to an event. This integrated approach to logistics and program planning – with the primary focus on the participant – gives us the edge.

  20. The Chelyabinsk Airburst Event

    NASA Astrophysics Data System (ADS)

    Boslough, Mark

    2013-10-01

    On Feb. 15, 2013, an asteroid exploded about 40 km from the Russian city of Chelyabinsk. Its proximity led to many injuries and widespread blast damage, but also yielded a plethora of data, providing means to determine the projectile size and entry parameters, and develop a self-consistent model. We will present results of the first physics simulations to be initialized with accurate energy deposition derived from observations. The best estimate of the explosive yield is 400-500 kilotons, making Chelyabinsk the most powerful such event observed since Tunguska (3-5 megatons). Analysis of video combined with subsequent on-site stellar calibrations enable precise estimates of entry velocity (19 km/s), angle (17° elevation) and altitude of peak brightness (29 km). This implies a pre-entry diameter of ~20 m and mass of ~1200 tonnes. Satellite sensors recorded the emission peak at 03:20:33 UT, with a total radiated energy of 3.75×1014 J 90 kilotons). A typical bolide luminous efficiency of 20% implies a total energy of ~450 kilotons, consistent with infrasound and other observations. The maximum radiant intensity was 2.7×1013 W/ster, corresponding to a magnitude of -28. The shallow entry angle led to a long bolide duration (16.5 s) and energy was deposited over 100s of km leading to an extended, near-horizontal, linear explosion. The blast was distributed over a large area, and was much weaker than for a steep entry and a more concentrated explosion closer to the surface. The orientation also led to different phenomena than expected for a more vertical entry. There was no ballistic plume as observed from SL9 impacts (45°) or calculated for Tunguska 35°). Instead, buoyant instabilities grew into mushroom clouds and bifurcated the trail into two contra-rotating vortices. Chelyabinsk and Tunguska are “once-per-century” and “once-per-millennium” events, respectively. These outliers imply that the frequency of large airbursts is underestimated. Models also

  1. The Chelyabinsk event

    NASA Astrophysics Data System (ADS)

    Borovička, Jiri

    2015-08-01

    On February 15, 2013, 3:20 UT, an asteroid of the size of about 19 meters and mass of 12,000 metric tons entered the Earth's atmosphere unexpectedly near the border of Kazakhstan and Russia. It was the largest confirmed Earth impactor since the Tunguska event in 1908. The body moved approximately westwards with a speed of 19 km/s, on a trajectory inclined 18 degrees to the surface, creating a fireball of steadily increasing brightness. Eleven seconds after the first sightings, the fireball reached its maximum brightness. At that point, it was located less than 40 km south from Chelyabinsk, a Russian city of population more than one million, at an altitude of 30 km. For people directly underneath, the fireball was 30 times brighter than the Sun. The cosmic body disrupted into fragments; the largest of them was visible for another five seconds before it disappeared at an altitude of 12.5 km, when it was decelerated to 3 km/s. Fifty six second later, that ~ 600 kg fragment landed in Lake Chebarkul and created an 8 m wide hole in the ice. More material remained, however, in the atmosphere forming a dust trail up to 2 km wide and extending along the fireball trajectory from altitude 18 to 70 km. People observing the dust trail from Chelyabinsk and other places were surprised by the arrival of a very strong blast wave 90 - 150 s after the fireball passage (depending on location). The wave, produced by the supersonic flight of the body, broke ~10% of windows in Chelyabinsk (~40% of buildings were affected). More than 1600 people were injured, mostly from broken glass. Small meteorites landed in an area 60 km long and several km wide and caused no damage. The meteorites were classified as LL ordinary chondrites and were interesting by the presence of two phases, light and dark. The dust left in the atmosphere circled the Earth within few days and formed a ring around the northern hemisphere.The whole event was well documented by video cameras, seismic and infrasonic

  2. Modeling four occurred debris flow events in the Dolomites area (North-Eastern Italian Alps)

    NASA Astrophysics Data System (ADS)

    Boreggio, Mauro; Gregoretti, Carlo; Degetto, Massimo; Bernard, Martino

    2016-04-01

    Four occurred debris flows in the Dolomites area (North-Eastern Italian Alps) are modeled by back-analysis. The four debris flows events are those occurred at Rio Lazer (Trento) on the 4th of November 1966, at Fiames (Belluno) on the 5th of July 2006, at Rovina di Cancia (Belluno) on the 18th of July 2009 and at Rio Val Molinara (Trento) on the 15th of August 2010. In all the events, runoff entrained sediments present on natural channels and formed a solid-liquid wave that routed downstream. The first event concerns the routing of debris flow on an inhabited fan. The second event the deviation of debris flow from the usual path due to an obstruction with the excavation of a channel in the scree and the downstream spreading in a wood. The third event concerns the routing of debris flow in a channel with an ending the reservoir, its overtopping and final spreading in the inhabited area. The fourth event concerns the routing of debris flow along the main channel downstream the initiation area until spreading just upstream a village. All the four occurred debris flows are simulated by modeling runoff that entrained debris flow for determining the solid-liquid hydrograph. The routing of the solid-liquid hydrograph is simulated by a bi-phase cell model based on the kinematic approach. The comparison between simulated and measured erosion and deposition depths is satisfactory. Nearly the same parameters for computing erosion and deposition were used for all the four occurred events. The maps of erosion and deposition depths are obtained by comparing the results of post-event surveys with the pre-event DEM. The post-event surveys were conducted by using different instruments (LiDAR and GPS) or the combination photos-single points depth measurements (in this last case it is possible obtaining the deposition/erosion depths by means of stereoscopy techniques).

  3. The Propagation of Solar Energetic Particles in Magnetic Channels

    NASA Technical Reports Server (NTRS)

    Mcdonald, F. B.; Burlaga, L. F.

    1985-01-01

    The existence of interplanetary flow systems produced by the entrainment of interplanetary transients, consisting of flare produced shocks, high speed solar wind streams and coronal mass ejection, has been established. This entrainment process produces enhanced regions of the interplanetary magnetic field that should be connected back to the solar corona. These compressed regions can provide a preferred magnetic channel for the propagation of solar cosmic rays. The characteristics of these events appear to be different from those previously reported by the NASA/University of New Hampshire team and the University of Chicago in their study of a large number of events in the region beyond 1 AU. These new events have a very flat energy spectra (with gamma = approx. 1.5) that frequently extend to energies above 100 MeV and have a significant enhancement of MeV electrons.

  4. Experimental modeling of depositional turbidity currents in a sinuous submarine channel

    NASA Astrophysics Data System (ADS)

    Ezz, Hesham; Cantelli, Alessandro; Imran, Jasim

    2013-05-01

    Submarine channels with intricate meandering patterns and extensive levees are recognized as products of density-driven flows known as turbidity currents. Compared to the fluvial meandering channels, understanding of the flow and morphodynamics of submarine channels is limited. In this paper, we present experimental results on the morphodynamic and stratigraphic evolution of a submarine channel from sedimentation due to the passage of successive flow events. A pre-formed sinuous channel with multiple bends, a trapezoidal cross section, and an initial thalweg slope of 0.43° was emplaced in a large tank. A total of 29 runs, each lasting an hour, were made by releasing heavier fluids containing salt and silica powder at a constant rate in the tank filled with fresh water. The overbank flow was restricted to curvature-induced flow stripping. The following observations were made from the experimental measurements; (i) asymmetric channel cross sections developed due to higher deposition rates on the outer bank of the channel bends, (ii) an apron or sediment wedge with overlain bedforms appeared near the channel entrance that prograded and aggraded with successive runs, (iii) overbank flow due to flow stripping at bend apices resulted in lobe-shaped deposits, (iv) a higher concentration of solute resulted in flow confinement, and (v) the flow velocity during later runs increased due to channel narrowing and steepening of the gradient.

  5. Molecular Dynamics Simulation of the Antiamoebin Ion Channel: Linking Structure and Conductance

    NASA Technical Reports Server (NTRS)

    Wilson, Michael A.; Wei, Chenyu; Bjelkmar, Paer; Wallace, B. A.; Pohorille, Andrew

    2011-01-01

    Molecular dynamics simulations were carried out in order to ascertain which of the potential multimeric forms of the transmembrane peptaibol channel, antiamoebin, is consistant with its measured conductance. Estimates of the conductance obtained through counting ions that cross the channel and by solving the Nernst-Planck equation yield consistent results, indicating that the motion of ions inside the channel can be satisfactorily described as diffusive.The calculated conductance of octameric channels is markedly higher than the conductance measured in single channel recordings, whereas the tetramer appears to be non-conducting. The conductance of the hexamer was estimated to be 115+/-34 pS and 74+/-20 pS, at 150 mV and 75 mV, respectively, in satisfactory agreement with the value of 90 pS measured at 75 mV. On this basis we propose that the antiamoebin channel consists of six monomers. Its pore is large enough to accommodate K(+) and Cl(-) with their first solvation shells intact. The free energy barrier encountered by K(+) is only 2.2 kcal/mol whereas Cl(-) encounters a substantially higher barrier of nearly 5 kcal/mol. This difference makes the channel selective for cations. Ion crossing events are shown to be uncorrelated and follow Poisson statistics. keywords: ion channels, peptaibols, channel conductance, molecular dynamics

  6. Genetic diversity of a newly established population of golden eagles on the Channel Islands, California

    USGS Publications Warehouse

    Sonsthagen, Sarah A.; Coonan, Timothy J.; Latta, Brian C.; Sage, George K.; Talbot, Sandra L.

    2012-01-01

    Gene flow can have profound effects on the genetic diversity of a founding population depending on the number and relationship among colonizers and the duration of the colonization event. Here we used data from nuclear microsatellite and mitochondrial DNA control region loci to assess genetic diversity in golden eagles of the recently colonized Channel Islands, California. Genetic diversity in the Channel Island population was low, similar to signatures observed for other recent colonizing island populations. Differences in levels of genetic diversity and structure observed between mainland California and the islands suggests that few individuals were involved in the initial founding event, and may have comprised a family group. The spatial genetic structure observed between Channel Island and mainland California golden eagle populations across marker types, and genetic signature of population decline observed for the Channel Island population, suggest a single or relatively quick colonization event. Polarity in gene flow estimates based on mtDNA confirm an initial colonization of the Channel Islands by mainland golden eagles, but estimates from microsatellite data suggest that golden eagles on the islands were dispersing more recently to the mainland, possibly after reaching the carrying capacity of the island system. These results illustrate the strength of founding events on the genetic diversity of a population, and confirm that changes to genetic diversity can occur within just a few generations.

  7. Generic theory for channel sinuosity

    PubMed Central

    Lazarus, Eli D.; Constantine, José Antonio

    2013-01-01

    Sinuous patterns traced by fluid flows are a ubiquitous feature of physical landscapes on Earth, Mars, the volcanic floodplains of the Moon and Venus, and other planetary bodies. Typically discussed as a consequence of migration processes in meandering rivers, sinuosity is also expressed in channel types that show little or no indication of meandering. Sinuosity is sometimes described as “inherited” from a preexisting morphology, which still does not explain where the inherited sinuosity came from. For a phenomenon so universal as sinuosity, existing models of channelized flows do not explain the occurrence of sinuosity in the full variety of settings in which it manifests, or how sinuosity may originate. Here we present a generic theory for sinuous flow patterns in landscapes. Using observations from nature and a numerical model of flow routing, we propose that flow resistance (representing landscape roughness attributable to topography or vegetation density) relative to surface slope exerts a fundamental control on channel sinuosity that is effectively independent of internal flow dynamics. Resistance-dominated surfaces produce channels with higher sinuosity than those of slope-dominated surfaces because increased resistance impedes downslope flow. Not limited to rivers, the hypothesis we explore pertains to sinuosity as a geomorphic pattern. The explanation we propose is inclusive enough to account for a wide variety of sinuous channel types in nature, and can serve as an analytical tool for determining the sinuosity a landscape might support. PMID:23610390

  8. River meanders and channel size

    USGS Publications Warehouse

    Williams, G.P.

    1986-01-01

    This study uses an enlarged data set to (1) compare measured meander geometry to that predicted by the Langbein and Leopold (1966) theory, (2) examine the frequency distribution of the ratio radius of curvature/channel width, and (3) derive 40 empirical equations (31 of which are original) involving meander and channel size features. The data set, part of which comes from publications by other authors, consists of 194 sites from a large variety of physiographic environments in various countries. The Langbein-Leopold sine-generated-curve theory for predicting radius of curvature agrees very well with the field data (78 sites). The ratio radius of curvature/channel width has a modal value in the range of 2 to 3, in accordance with earlier work; about one third of the 79 values is less than 2.0. The 40 empirical relations, most of which include only two variables, involve channel cross-section dimensions (bankfull area, width, and mean depth) and meander features (wavelength, bend length, radius of curvature, and belt width). These relations have very high correlation coefficients, most being in the range of 0.95-0.99. Although channel width traditionally has served as a scale indicator, bankfull cross-sectional area and mean depth also can be used for this purpose. ?? 1986.

  9. TRP channels in the skin

    PubMed Central

    Tóth, Balázs I; Oláh, Attila; Szöllősi, Attila Gábor; Bíró, Tamás

    2014-01-01

    Emerging evidence suggests that transient receptor potential (TRP) ion channels not only act as ‘polymodal cellular sensors’ on sensory neurons but are also functionally expressed by a multitude of non-neuronal cell types. This is especially true in the skin, one of the largest organs of the body, where they appear to be critically involved in regulating various cutaneous functions both under physiological and pathophysiological conditions. In this review, we focus on introducing the roles of several cutaneous TRP channels in the regulation of the skin barrier, skin cell proliferation and differentiation, and immune functions. Moreover, we also describe the putative involvement of several TRP channels in the development of certain skin diseases and identify future TRP channel-targeted therapeutic opportunities. Linked Articles This article is part of a themed section on the pharmacology of TRP channels. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-10 PMID:24372189

  10. Gramicidin channels are internally gated.

    PubMed

    Jones, Tyson L; Fu, Riqiang; Nielson, Frederick; Cross, Timothy A; Busath, David D

    2010-04-21

    Gramicidin channels are archetypal molecular subjects for solid-state NMR studies and investigations of single-channel or cation conductance. Until now, the transitions between on and off conductance states have been thought, based on multichannel studies, to represent monomer <--> dimer reactions. Here we use a single-molecule deposition method (vesicle fusion to a planar bilayer) to show that gramicidin dimer channels do not normally dissociate when conductance terminates. Furthermore, the observation of two 13C peaks in solid-state NMR indicates very stable dichotomous conformations for both the first and second peptide bonds in the monomers, and a two-dimensional chemical exchange spectrum with a 12-s mixing time demonstrates that the Val1 carbonyl conformations exchange slowly, with lifetimes of several seconds. It is proposed that gramicidin channels are gated by small conformational changes in the channel near the permeation pathway. These studies demonstrate how regulation of conformations governing closed <--> open transitions may be achieved and studied at the molecular level.

  11. Charged and Neutral Particles Channeling Phenomena Channeling 2008

    NASA Astrophysics Data System (ADS)

    Dabagov, Sultan B.; Palumbo, Luigi

    2010-04-01

    On the discovery of coherent Bremsstrahlung in a single crystal at the Frascati National Laboratories / C. Barbiellini, G. P. Murtas and S. B. Dabagov -- Advances in coherent Bremsstrahlung and LPM-effect studies (to the lOOth anniversary from the birth of L. D. Landau) / N. F. Shul'ga -- Spectra of radiation and created particles at intermediate energy in oriented crystal taking into account energy loss / V. N. Baier and V. M. Katkov -- The coherent Bremsstrahlung beam at MAX-lab facility / K. Fissum ... [et al.] -- Radiation from thin, structured targets (CERN NA63) / A. Dizdar -- Hard incoherent radiation in thick crystals / N. F. Shul'ga, V. V. Syshchenko and A. I. Tarnovsky -- Coherent Bremsstrahlung in periodically deformed crystals with a complex base / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Induction of coherent x-ray Bremsstrahlung in crystals under the influence of acoustic waves / A. R. Mkrtchyan and V. V. Parazian -- Coherent processes in bent single crystals / V. A. Maisheev -- Experimental and theoretical investigation of complete transfer phenomenon for media with various heat exchange coefficients / A. R. Mkrtchyan, A. E. Movsisyan and V. R. Kocharyan -- Coherent pair production in crystals / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Negative particle planar and axial channeling and channeling collimation / R. A. Carrigan, Jr. -- CERN crystal-based collimation in modern hadron colliders / W. Scandale -- Studies and application of bent crystals for beam steering at 70 GeV IHEP accelerator / A. G. Afonin ... [et al.] -- Crystal collimation studies at the Tevatron (T-980) / N. V. Mokhov ... [et al.] -- Fabrication of crystals for channeling of particles in accellerators / A. Mazzolari ... [et al.] -- New possibilities to facilitate collimation of both positively and negatively charged particle beams by crystals / V. Guidi, A. Mazzolari and V. V. Tikhomirov -- Increase of probability of particle capture into the channeling

  12. Scaling and pattern of extreme geomorphic events in a mountain basin, Idaho, USA

    NASA Astrophysics Data System (ADS)

    Luce, C. H.; Rieman, B. E.; McKean, J. A.; Dunham, J. B.; King, J. G.

    2003-12-01

    While extreme events are rare in individual streams or stream reaches, the occurrence of an extreme event somewhere within an ensemble of streams can be commonplace. The relationship between event frequency and magnitude for large units of analysis depends on the size of area considered and the spatial continuity of events. Some of the more extreme geomorphic events affect only a limited spatial area. Limitations to area relate to spatial extents of event triggers such as fires, thunderstorms, or rain-on-snow. Understanding the size of extreme events is important in approaching the frequency-magnitude relationships for larger analysis frames and clarifying the role of extreme events at different spatial scales. Sequential mapping of channel reorganizing events from aerial photography records dating back 40 years in the Boise River basin reveal important characteristics of severe disturbances in a spatial context. The most relevant to this discussion is that there is little coherence in extreme events beyond 10 km. Patterns of occurrence for fishes occupying these streams may reflect historic patterns of extinction and colonization following catastrophic disturbance. These patterns and recent data on apparent gene flow among streams suggest that scaling of ecological processes is concordant with the patterns of channel disturbance we have identified here. There is evidence that this scale relates more to the scale of driving storm events than to pre-existing land disturbances such as fire, logging, or grazing. One puzzle is that some areas seem more prone to multiple events than others, which may relate to underlying variation in lithology and exposure to weather. Lithology also constrains the temporal signature of extreme events. The spatial extent of events may serve as a valuable metric of event magnitude to gauge their ecological influence.

  13. Social Media Visual Analytics for Events

    NASA Astrophysics Data System (ADS)

    Diakopoulos, Nicholas; Naaman, Mor; Yazdani, Tayebeh; Kivran-Swaine, Funda

    For large-scale multimedia events such as televised debates and speeches, the amount of content on social media channels such as Facebook or Twitter can easily become overwhelming, yet still contain information that may aid and augment understanding of the multimedia content via individual social media items, or aggregate information from the crowd's response. In this work we discuss this opportunity in the context of a social media visual analytic tool, Vox Civitas, designed to help journalists, media professionals, or other researchers make sense of large-scale aggregations of social media content around multimedia broadcast events. We discuss the design of the tool, present and evaluate the text analysis techniques used to enable the presentation, and detail the visual and interaction design. We provide an exploratory evaluation based on a user study in which journalists interacted with the system to analyze and report on a dataset of over one 100 000 Twitter messages collected during the broadcast of the U.S. State of the Union presidential address in 2010.

  14. Researches toward potassium channels on tumor progressions.

    PubMed

    Shen, Zheng; Yang, Qian; You, Qidong

    2009-01-01

    As trans-membrane proteins located in cytoplasm and organelle membrane, potassium (K(+)) channels are generally divided into four super-families: voltage-gated K(+) channels (K(v)), Ca(2+)-activated K(+) channels (K(Ca)), inwardly rectifying K(+) channels (K(ir)) and two-pore domain K(+) channels (K(2P)). Since dysfunctions of K(+) channels would induce many diseases, various studies toward their functions in physiologic and pathologic process have been extensively launched. This review focuses on the recent advances of K(+) channels in tumor progression, including the brief introduction of K(+) channels, the role of K(+) channels in tumor cells, the possible mechanism of action at cellular level, and the possible application of K(+) channel modulators in cancer chemotherapy.

  15. Insect sodium channels and insecticide resistance

    PubMed Central

    2011-01-01

    Voltage-gated sodium channels are essential for the generation and propagation of action potentials (i.e., electrical impulses) in excitable cells. Although most of our knowledge about sodium channels is derived from decades of studies of mammalian isoforms, research on insect sodium channels is revealing both common and unique aspects of sodium channel biology. In particular, our understanding of the molecular dynamics and pharmacology of insect sodium channels has advanced greatly in recent years, thanks to successful functional expression of insect sodium channels in Xenopus oocytes and intensive efforts to elucidate the molecular basis of insect resistance to insecticides that target sodium channels. In this review, I discuss recent literature on insect sodium channels with emphases on the prominent role of alternative splicing and RNA editing in the generation of functionally diverse sodium channels in insects and the current understanding of the interactions between insect sodium channels and insecticides. PMID:17206406

  16. TRP channel Ca2+ sparklets: fundamental signals underlying endothelium-dependent hyperpolarization

    PubMed Central

    Sullivan, Michelle N.

    2013-01-01

    Important functions of the vascular endothelium, including permeability, production of antithrombotic factors, and control of vascular tone, are regulated by changes in intracellular Ca2+. The molecular identities and regulation of Ca2+ influx channels in the endothelium are incompletely understood, in part because of experimental difficulties associated with application of patch-clamp electrophysiology to native endothelial cells. However, advances in confocal and total internal reflection fluorescence microscopy and the development of fast, high-affinity Ca2+-binding fluorophores have recently allowed for direct visualization and characterization of single-channel transient receptor potential (TRP) channel Ca2+ influx events in endothelial cells. These events, called “TRP channel Ca2+ sparklets,” have been optically recorded from primary endothelial cells and the intact endothelium, and the biophysical properties and fundamental significance of these Ca2+ signals in vasomotor regulation have been characterized. This review will first briefly discuss the role of endothelial cell TRP channel Ca2+ influx in endothelium-dependent vasodilation, describe improved methods for recording unitary TRP channel activity using optical methods, and highlight discoveries regarding the regulation and physiological significance of TRPV4 Ca2+ sparklets in the vascular endothelium enabled by this new technology. Perspectives on the potential use of these techniques to evaluate changes in TRP channel Ca2+ influx activity associated with endothelial dysfunction are offered. PMID:24025865

  17. Tidal disruption event demographics

    NASA Astrophysics Data System (ADS)

    Kochanek, C. S.

    2016-09-01

    We survey the properties of stars destroyed in tidal disruption events (TDEs) as a function of black hole (BH) mass, stellar mass and evolutionary state, star formation history and redshift. For M_{BH} ≲ 10^7 M_{⊙}, the typical TDE is due to a M* ˜ 0.3 M⊙ M-dwarf, although the mass function is relatively flat for M_{ast } ≲ M_{⊙}. The contribution from older main-sequence stars and sub-giants is small but not negligible. From MBH ≃ 107.5-108.5 M⊙, the balance rapidly shifts to higher mass stars and a larger contribution from evolved stars, and is ultimately dominated by evolved stars at higher BH masses. The star formation history has little effect until the rates are dominated by evolved stars. TDE rates should decline very rapidly towards higher redshifts. The volumetric rate of TDEs is very high because the BH mass function diverges for low masses. However, any emission mechanism which is largely Eddington-limited for low BH masses suppresses this divergence in any observed sample and leads to TDE samples dominated by MBH ≃ 106.0-107.5 M⊙ BHs with roughly Eddington peak accretion rates. The typical fall-back time is relatively long, with 16 per cent having tfb < 10-1 yr (37 d), and 84 per cent having longer time-scales. Many residual rate discrepancies can be explained if surveys are biased against TDEs with these longer tfb, which seems very plausible if tfb has any relation to the transient rise time. For almost any BH mass function, systematic searches for fainter, faster time-scale TDEs in smaller galaxies, and longer time-scale TDEs in more massive galaxies are likely to be rewarded.

  18. Significant Tsunami Events

    NASA Astrophysics Data System (ADS)

    Dunbar, P. K.; Furtney, M.; McLean, S. J.; Sweeney, A. D.

    2014-12-01

    Tsunamis have inflicted death and destruction on the coastlines of the world throughout history. The occurrence of tsunamis and the resulting effects have been collected and studied as far back as the second millennium B.C. The knowledge gained from cataloging and examining these events has led to significant changes in our understanding of tsunamis, tsunami sources, and methods to mitigate the effects of tsunamis. The most significant, not surprisingly, are often the most devastating, such as the 2011 Tohoku, Japan earthquake and tsunami. The goal of this poster is to give a brief overview of the occurrence of tsunamis and then focus specifically on several significant tsunamis. There are various criteria to determine the most significant tsunamis: the number of deaths, amount of damage, maximum runup height, had a major impact on tsunami science or policy, etc. As a result, descriptions will include some of the most costly (2011 Tohoku, Japan), the most deadly (2004 Sumatra, 1883 Krakatau), and the highest runup ever observed (1958 Lituya Bay, Alaska). The discovery of the Cascadia subduction zone as the source of the 1700 Japanese "Orphan" tsunami and a future tsunami threat to the U.S. northwest coast, contributed to the decision to form the U.S. National Tsunami Hazard Mitigation Program. The great Lisbon earthquake of 1755 marked the beginning of the modern era of seismology. Knowledge gained from the 1964 Alaska earthquake and tsunami helped confirm the theory of plate tectonics. The 1946 Alaska, 1952 Kuril Islands, 1960 Chile, 1964 Alaska, and the 2004 Banda Aceh, tsunamis all resulted in warning centers or systems being established.The data descriptions on this poster were extracted from NOAA's National Geophysical Data Center (NGDC) global historical tsunami database. Additional information about these tsunamis, as well as water level data can be found by accessing the NGDC website www.ngdc.noaa.gov/hazard/

  19. Continuous equal channel angular pressing

    DOEpatents

    Zhu, Yuntian T.; Lowe, Terry C.; Valiev, Ruslan Z.; Raab, Georgy J.

    2006-12-26

    An apparatus that continuously processes a metal workpiece without substantially altering its cross section includes a wheel member having an endless circumferential groove, and a stationary constraint die that surrounds the wheel member, covers most of the length of the groove, and forms a passageway with the groove. The passageway has a rectangular shaped cross section. An abutment member projects from the die into the groove and blocks one end of the passageway. The wheel member rotates relative to the die in the direction toward the abutment member. An output channel in the die adjacent the abutment member has substantially the same cross section as the passageway. A metal workpiece is fed through an input channel into the passageway and carried in the groove by frictional drag in the direction towards the abutment member, and is extruded through the output channel without any substantial change in cross section.

  20. Channeled spectropolarimetry using iterative reconstruction

    NASA Astrophysics Data System (ADS)

    Lee, Dennis J.; LaCasse, Charles F.; Craven, Julia M.

    2016-05-01

    Channeled spectropolarimeters (CSP) measure the polarization state of light as a function of wavelength. Conventional Fourier reconstruction suffers from noise, assumes the channels are band-limited, and requires uniformly spaced samples. To address these problems, we propose an iterative reconstruction algorithm. We develop a mathematical model of CSP measurements and minimize a cost function based on this model. We simulate a measured spectrum using example Stokes parameters, from which we compare conventional Fourier reconstruction and iterative reconstruction. Importantly, our iterative approach can reconstruct signals that contain more bandwidth, an advancement over Fourier reconstruction. Our results also show that iterative reconstruction mitigates noise effects, processes non-uniformly spaced samples without interpolation, and more faithfully recovers the ground truth Stokes parameters. This work offers a significant improvement to Fourier reconstruction for channeled spectropolarimetry.

  1. Sodium Channel Inhibiting Marine Toxins

    NASA Astrophysics Data System (ADS)

    Llewellyn, Lyndon E.

    Saxitoxin (STX), tetrodotoxin (TTX) and their many chemical relatives are part of our daily lives. From killing people who eat seafood containing these toxins, to being valuable research tools unveiling the invisible structures of their pharmacological receptor, their global impact is beyond measure. The pharmacological receptor for these toxins is the voltage-gated sodium channel which transports Na ions between the exterior to the interior of cells. The two structurally divergent families of STX and TTX analogues bind at the same location on these Na channels to stop the flow of ions. This can affect nerves, muscles and biological senses of most animals. It is through these and other toxins that we have developed much of our fundamental understanding of the Na channel and its part in generating action potentials in excitable cells.

  2. Muon cooling in a quadrupole magnet channel

    SciTech Connect

    Neuffer, David; Poklonskiy, A.; /Michigan State U.

    2007-10-01

    As discussed before,[1] a cooling channel using quadrupole magnets in a FODO transport channel can be used for initial cooling of muons. In the present note we discuss this possibility of a FODO focusing channel for cooling, and we present ICOOL simulations of muon cooling within a FODO channel. We explore a 1.5m cell-length cooling channel that could be used for the initial transverse cooling stage of a muon collider or neutrino factory.

  3. Voltage-Gated Sodium Channels

    NASA Astrophysics Data System (ADS)

    Hanck, Dorothy A.; Fozzard, Harry A.

    Voltage-gated sodium channels subserve regenerative excitation throughout the nervous system, as well as in skeletal and cardiac muscle. This excitation results from a voltage-dependent mechanism that increases regeneratively and selectively the sodium conductance of the channel e-fold for a 4-7 mV depolarization of the membrane with time constants in the range of tens of microseconds. Entry of Na+ into the cell without a companion anion depolarizes the cell. This depolarization, called the action potential, is propagated at rates of 1-20 meters/sec. In nerve it subserves rapid transmission of information and, in muscle cells, coordinates the trigger for contraction. Sodium-dependent action potentials depolarize the membrane to inside positive values of about 30-40 mV (approaching the electrochemical potential for the transmembrane sodium gradient). Repolarization to the resting potential (usually between -60 and -90 mV) occurs because of inactivation (closure) of sodium channels, which is assisted in different tissues by variable amounts of activation of voltage-gated potassium channels. This sequence results in all-or-nothing action potentials in nerve and fast skeletal muscle of 1-2 ms duration, and in heart muscle of 100-300 ms duration. Recovery of regenerative excitation, i.e., recovery of the ability of sodium channels to open, occurs after restoration of the resting potential with time constants of a few to several hundreds of milliseconds, depending on the channel isoform, and this rate controls the minimum interval for repetitive action potentials (refractory period).

  4. Single-Event Upset and Snapback in Silicon-on-Insulator Devices and Integrated Circuits

    SciTech Connect

    DODD,PAUL E.; SHANEYFELT,MARTY R.; WALSH,DAVID S.; SCHWANK,JAMES R.; HASH,GERALD L.; LOEMKER,RHONDA ANN; DRAPER,BRUCE L.; WINOKUR,PETER S.

    2000-08-15

    The characteristics Of ion-induced charge collection and single-event upset are studied in SOI transistors and circuits with various body tie structures. Impact ionization effects including single-event snapback are shown to be very important. Focused ion microbeam experiments are used to find single-event snapback drain voltage thresholds in n-channel SOI transistors as a function of device width. Three-Dimensional device simulations are used to determine single-event upset and snapback thresholds in SOI SRAMS, and to study design tradeoffs for various body-tie structures. A window of vulnerability to single-event snapback is shown to exist below the single-event upset threshold. The presence of single-event snapback in commercial SOI SRAMS is confirmed through broadbeam ion testing, and implications for hardness assurance testing of SOI integrated circuits are discussed.

  5. Noisy quantum phase communication channels

    NASA Astrophysics Data System (ADS)

    Teklu, Berihu; Trapani, Jacopo; Olivares, Stefano; Paris, Matteo G. A.

    2015-06-01

    We address quantum phase channels, i.e communication schemes where information is encoded in the phase-shift imposed to a given signal, and analyze their performances in the presence of phase diffusion. We evaluate mutual information for coherent and phase-coherent signals, and for both ideal and realistic phase receivers. We show that coherent signals offer better performances than phase-coherent ones, and that realistic phase channels are effective ones in the relevant regime of low energy and large alphabets.

  6. Channel incision and water quality

    NASA Astrophysics Data System (ADS)

    Shields, F. D.

    2009-12-01

    Watershed development often triggers channel incision that leads to radical changes in channel morphology. Although morphologic evolution due to channel incision has been documented and modeled by others, ecological effects, particularly water quality effects, are less well understood. Furthermore, environmental regulatory frameworks for streams frequently focus on stream water quality and underemphasize hydrologic and geomorphic issues. Discharge, basic physical parameters, solids, nutrients (nitrogen and phosphorus), chlorophyll and bacteria were monitored for five years at two sites along a stream in a mixed cover watershed characterized by rapid incision of the entire channel network. Concurrent data were collected from two sites on a nearby stream draining a watershed of similar size and cultivation intensity, but without widespread incision. Data sets describing physical aquatic habitat and fish fauna of each stream were available from other studies. The second stream was impacted by watershed urbanization, but was not incised, so normal channel-floodplain interaction maintained a buffer zone of floodplain wetlands between the study reach and the urban development upstream. The incised stream had mean channel depth and width that were 1.8 and 3.5 times as large as for the nonincised stream, and was characterized by flashier hydrology. The median rise rate for the incised stream was 6.4 times as great as for the nonincised stream. Correlation analyses showed that hydrologic perturbations were associated with water quality degradation, and the incised stream had levels of turbidity and solids that were two to three times higher than the nonincised, urbanizing stream. Total phosphorus, total Kjeldahl N, and chlorophyll a concentrations were significantly higher in the incised stream, while nitrate was significantly greater in the nonincised, urbanizing stream (p < 0.02). Physical aquatic habitat and fish populations in the nonincised urbanizing stream were

  7. Eight-Channel Continuous Timer

    NASA Technical Reports Server (NTRS)

    Cole, Steven

    2004-01-01

    A custom laboratory electronic timer circuit measures the durations of successive cycles of nominally highly stable input clock signals in as many as eight channels, for the purpose of statistically quantifying the small instabilities of these signals. The measurement data generated by this timer are sent to a personal computer running software that integrates the measurements to form a phase residual for each channel and uses the phase residuals to compute Allan variances for each channel. (The Allan variance is a standard statistical measure of instability of a clock signal.) Like other laboratory clock-cycle-measuring circuits, this timer utilizes an externally generated reference clock signal having a known frequency (100 MHz) much higher than the frequencies of the input clock signals (between 100 and 120 Hz). It counts the number of reference-clock cycles that occur between successive rising edges of each input clock signal of interest, thereby affording a measurement of the input clock-signal period to within the duration (10 ns) of one reference clock cycle. Unlike typical prior laboratory clock-cycle-measuring circuits, this timer does not skip some cycles of the input clock signals. The non-cycle-skipping feature is an important advantage because in applications that involve integration of measurements over long times for characterizing nominally highly stable clock signals, skipping cycles can degrade accuracy. The timer includes a field-programmable gate array that functions as a 20-bit counter running at the reference clock rate of 100 MHz. The timer also includes eight 20-bit latching circuits - one for each channel - at the output terminals of the counter. Each transition of an input signal from low to high causes the corresponding latching circuit to latch the count at that instant. Each such transition also sets a status flip-flop circuit to indicate the presence of the latched count. A microcontroller reads the values of all eight status flipflops

  8. An Integrated Distributed Watershed Model with Channel Network for Rainfall Runoff Simulation

    NASA Astrophysics Data System (ADS)

    Keesara, V.; T. I., E.; E. P., R.; A. T., K.

    2008-05-01

    convert the ASCII files of DEM, slope, soil and land use of watershed into map format. Drainage map of the watershed is generated based on DEM using Hydrology tools of ArcMap. The finite element grid has been prepared by dividing the whole watershed into seven sub watersheds using digitization tools of ArcMap. Here, each sub watershed is discretized into overland flow strips which are connected to one discretized channel. The discretized channels of all sub watersheds are connected as dendritic channel network. The model has been calibrated for four rainfall events and validated for two rainfall events of the watershed. Sensitivity analysis has also been performed by altering the calibrated parameters. From the simulation results, it is seen that, channel network based distributed model is able to simulate the rainfall events fairly. Present model can be applied to small to medium watersheds effectively.

  9. Ion Channels as Single Molecular Sensors: Extracting Information from Noise

    NASA Astrophysics Data System (ADS)

    Goychuk, Igor

    2001-03-01

    Ion channels are the evolution's solution to participate in electrical signaling. A question that has been haunting the Stochastic Resonance (SR) community ever since its first evidence in biological systems in the early nineties is whether -- and how -- SR occurs in single and/or coupled ion channels. Up to this very date, there exists no convincing experimental proof that SR actually takes place in a realistic ion channel such as the Shaker IR potassium-selective channel. The idea, however, that the environmental noise assists in a beneficial manner the transduction of electric encoded information is appealing; i.e. the occurrence of SR on this most fundamental level of biological complexity should not come as too big a surprise. In order to elucidate this prominent challenge we theoretically have investigated SR for a simple, yet realistic enough model of a voltage-gated ion channel. In doing so, we model the process of successive opening and closing events by a continuous time, two-state random point process with experimentally determined residence time distributions. Using measures of information theory such as the rate of information gain we have shown that SR indeed occurs when the closed state of the channel is predominantly dwelled. With increasing opening probability noise deteriorates the rate of information transfer that eventually assumes a robust behavior, which is essentially insensitive to noise. (I. Goychuk and P. Hänggi, Phys. Rev. E 61), 4272 (2000); Eur. Biophys. J. 29, 345 (2000). Moreover, we study additional SR measures such as the spectral amplification and the signal-to-noise ratio. In a next step, we generalize this investigation to account also for non-Markovian conductance fluctuations with nonexponential residence time distributions and study their consequences for the likelihood for SR to persist.

  10. Extreme events in computational turbulence

    PubMed Central

    Yeung, P. K.; Zhai, X. M.; Sreenivasan, Katepalli R.

    2015-01-01

    We have performed direct numerical simulations of homogeneous and isotropic turbulence in a periodic box with 8,1923 grid points. These are the largest simulations performed, to date, aimed at improving our understanding of turbulence small-scale structure. We present some basic statistical results and focus on “extreme” events (whose magnitudes are several tens of thousands the mean value). The structure of these extreme events is quite different from that of moderately large events (of the order of 10 times the mean value). In particular, intense vorticity occurs primarily in the form of tubes for moderately large events whereas it is much more “chunky” for extreme events (though probably overlaid on the traditional vortex tubes). We track the temporal evolution of extreme events and find that they are generally short-lived. Extreme magnitudes of energy dissipation rate and enstrophy occur simultaneously in space and remain nearly colocated during their evolution. PMID:26424452

  11. Extreme events in computational turbulence.

    PubMed

    Yeung, P K; Zhai, X M; Sreenivasan, Katepalli R

    2015-10-13

    We have performed direct numerical simulations of homogeneous and isotropic turbulence in a periodic box with 8,192(3) grid points. These are the largest simulations performed, to date, aimed at improving our understanding of turbulence small-scale structure. We present some basic statistical results and focus on "extreme" events (whose magnitudes are several tens of thousands the mean value). The structure of these extreme events is quite different from that of moderately large events (of the order of 10 times the mean value). In particular, intense vorticity occurs primarily in the form of tubes for moderately large events whereas it is much more "chunky" for extreme events (though probably overlaid on the traditional vortex tubes). We track the temporal evolution of extreme events and find that they are generally short-lived. Extreme magnitudes of energy dissipation rate and enstrophy occur simultaneously in space and remain nearly colocated during their evolution. PMID:26424452

  12. A multi-channel distributed DAQ for n-TPC

    NASA Astrophysics Data System (ADS)

    Cheng, Xiao-Lei; Liu, Jian-Fang; Yu, Qian; Niu, Li-Bo; Li, Yu-Lan

    2015-11-01

    A new fast neutron spectrometer named n-TPC has been designed by LPRI (Key Laboratory of Particle & Radiation Imaging, Ministry of Education) at Tsinghua University. The neutron energy spectrum can be calculated from the recoil angle and energy of the recoil proton detected by a 704-pad GEM-TPC. In beam tests at IHIP (Institute of Heavy Ion Physics, Peking University) in 2014, n-TPC performed better than 6%@6 MeV energy resolution and 5‰ detection efficiency. To find the best working parameters (the component and proportion of the gas, the high voltage between each GEM layer, etc.) of the n-TPC and support its application in various conditions, a multichannel distributed DAQ has been designed to read out the signals from the 704 channels. With over 25 Ms/s sampling rate and 12 bit resolution for each channel, it can record the time and amplitude information as well as traditional DAQs in the TPC application domain. The main design objective of this distributed DAQ, however, is more flexible parameter modulation and operation. It can support the n-TPC without the limitation of the chassis and categorize signals arriving from the 704 channels at the same time by different events without event triggers. Supported by National Natural Science Foundation of China (11275109)

  13. 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

  14. Potassium conductance of the squid giant axon. Single-channel studies

    PubMed Central

    1988-01-01

    The patch-clamp technique was implemented in the cut-open squid giant axon and used to record single K channels. We present evidence for the existence of three distinct types of channel activities. In patches that contained three to eight channels, ensemble fluctuation analysis was performed to obtain an estimate of 17.4 pS for the single-channel conductance. Averaged currents obtained from these multichannel patches had a time course of activation similar to that of macroscopic K currents recorded from perfused squid giant axons. In patches where single events could be recorded, it was possible to find channels with conductances of 10, 20, and 40 pS. The channel most frequently encountered was the 20-pS channel; for a pulse to 50 mV, this channel had a probability of being open of 0.9. In other single-channel patches, a channel with a conductance of 40 pS was present. The activity of this channel varied from patch to patch. In some patches, it showed a very low probability of being open (0.16 for a pulse to 50 mV) and had a pronounced lag in its activation time course. In other patches, the 40-pS channel had a much higher probability of being open (0.75 at a holding potential of 50 mV). The 40-pS channel was found to be quite selective for K over Na. In some experiments, the cut-open axon was exposed to a solution containing no K for several minutes. A channel with a conductance of 10 pS was more frequently observed after this treatment. Our study shows that the macroscopic K conductance is a composite of several K channel types, but the relative contribution of each type is not yet clear. The time course of activation of the 20-pS channel and the ability to render it refractory to activation only by holding the membrane potential at a positive potential for several seconds makes it likely that it is the predominant channel contributing to the delayed rectifier conductance. PMID:3171538

  15. MINOS atmospheric neutrino contained events

    SciTech Connect

    Habig, A.; /Minnesota U.

    2007-10-01

    The Main Injector Neutrino Oscillation Search (MINOS) experiment has continued to collect atmospheric neutrino events while doing a precision measurement of NuMI beam {nu}{sub {mu}} disappearance oscillations. The 5.4 kton iron calorimeter is magnetized to provide the unique capability of discriminating between {nu}{sub {mu}} and {bar {nu}}{sub {mu}} interactions on an event-by-event basis and has been collecting atmospheric neutrino data since July 2003. An analysis of the neutrino events with interaction vertices contained inside the detector will be presented.

  16. 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

  17. Mars' Ionospheric Response to Extreme Space Weather Events

    NASA Astrophysics Data System (ADS)

    Ulusen, D.; Brain, D.; Luhmann, J. G.; Mitchell, D.

    2011-12-01

    Extreme space weather events induce a variety of disturbances in the near space environment of planets. At Mars, which is not well protected due to lack of a global dipole field, these effects are expected to be more violent than at other planets. Mainly because of limited monitoring, the influence of these extreme events on the near Mars space has been investigated only in a few studies. The Electron Reflectometer (ER) onboard the Mars Global Surveyor (MGS) spacecraft was capable of indirectly detecting space weather events through background high energy particle flux measurements at the highest energy channels of the instrument. Over more than a seven year period these background measurements provide a data set of the energetic particle environment at Mars covering a broad spectrum of space weather events. We will present the results of a study correlating extreme events in MGS ER measurements with MGS Magnetometer and Radio Science experiment observations of the Martian ionosphere. Our results confirm the immediate photo-enhancement effect of the impulsive solar radiation during these extremes on the Martian ionosphere; however, show no clear evidence of an ionospheric enhancement due to energetic charged particles associated with the extreme events compared to quiet times' particle environment. Through in-depth case studies and statistical analysis of the entire data set which cover almost a complete solar cycle, we discuss implications of our findings and provide insight for the upcoming solar maximum at Mars.

  18. High Energy Particle Events in Solar Cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Thakur, N.; Gopalswamy, N.; Makela, P. A.; Yashiro, S.; Akiyama, S.; Xie, H.

    2014-12-01

    We present a study of high-energy solar energetic particle (SEP) events in solar cycles 23 and 24 using GOES data. We selected large SEP events, which showed intensity enhancements in the >500 MeV and >700 MeV GOES energy channels. A study of cycle 24 and the first half of cycle 23 ground level enhancements (GLEs) by Gopalswamy et al. 2014 showed that typically, SEP events with intensity enhancement at >700 MeV have been associated with GLEs. We have extended the survey to cover the whole cycle 23. Our preliminary survey confirms this to be true for all except for three cases. There were two GLEs (1998/05/06 and 2006/12/06) for which a clear increase in >700 MeV protons was not observed by GOES. There was one high energy SEP event (2000/11/08), for which GOES observed >700 MeV protons but no GLE was produced. Here we compare all the high-energy particle events from cycles 23 and 24 with GLEs. We also compare energy spectra of all high-energy SEP events with those that produced GLEs. Work supported by NASA's Living with a Star Program. Ref.: Gopalswamy et al. 2014, GRL, 41, 2673

  19. Channel erosion surveys along TAPS route, Alaska, 1976

    USGS Publications Warehouse

    Doyle, Paul F.; Childers, Joseph M.

    1977-01-01

    Channel surveys were made along the TAPS (Trans-Alaska Pipeline System) route during 1976 at the same 27 sites that were surveyed in 1975. One additional site was put under surveillance in 1976. Except for construction changes wrought by installation of the pipeline, most of the sites surveyed showed very little change since the 1975 surveys. Some of the significant events of 1976 at the monitored crossing sites include: glacier-dammed lake break-out floods on the Tazlina and Tsina Rivers, severe icings on the Gulkana River which resulted in a spring flood 3-4 feet (1 meter) over banktop, and virtual completion of all the buried crossings and all but one overhead crossing before the 1976 channel erosion resurveys were made. Aerial photogrammetric surveys were used again in 1976 on the same seven sites as in 1975. Comparison of the photogrammetric surveys with each other and with on-the-ground surveys indicate that the method is generally applicable for channel erosion studies. However, it requires engineering judgement and personal knowledge of the site to avoid reaching inaccurate conclusions about channel change in some instances. (Woodard-USGS)

  20. Reconstruction of lightning channel geometry by localizing thunder sources

    NASA Astrophysics Data System (ADS)

    Bodhika, J. A. P.; Dharmarathna, W. G. D.; Fernando, Mahendra; Cooray, Vernon

    2013-09-01

    Thunder is generated as a result of a shock wave created by sudden expansion of air in the lightning channel due to high temperature variations. Even though the highest amplitudes of thunder signatures are generated at the return stroke stage, thunder signals generated at other events such as preliminary breakdown pulses also can be of amplitudes which are large enough to record using a sensitive system. In this study, it was attempted to reconstruct the lightning channel geometry of cloud and ground flashes by locating the temporal and spatial variations of thunder sources. Six lightning flashes were reconstructed using the recorded thunder signatures. Possible effects due to atmospheric conditions were neglected. Numerical calculations suggest that the time resolution of the recorded signal and 10 ms-1error in speed of sound leads to 2% and 3% errors, respectively, in the calculated coordinates. Reconstructed channel geometries for cloud and ground flashes agreed with the visual observations. Results suggest that the lightning channel can be successfully reconstructed using this technique.

  1. Generation of Martian chaos and channels by debris flows

    NASA Astrophysics Data System (ADS)

    Nummedal, D.; Prior, D. B.

    1981-01-01

    A debris flow mechanism is proposed to account for the formation of chaos and the large channels debouching into Crysae Planitia from the adjacent southern uplands of Mars. Based on considerations of the juxtaposition of individual channel environments, the morphological assemblages within each environment and flow dynamics, it is suggested that the debris flows were triggered by the large-scale failure of subsurface sediments, possibly initiated by a seismic event. During the initial, slow-moving phase of the flow, the debris would have formed gently sinuous channels with multiple side-wall slumps, grooves and ridges, and elongate erosional remnants. The flow would have gained mobility as the debris moved downslope, producing travel distances greatly in excess of those characteristic of terrestrial examples, and eroded, streamlined remnants at the distal reaches of the channel. Finally, due to internal and boundary friction, the flow would have been slowed down once it entered the Chryse plains, resulting in a thin debris blanket with no depositional relief.

  2. Channel function reconstitution and re-animation: a single-channel strategy in the postcrystal age.

    PubMed

    Oiki, Shigetoshi

    2015-06-15

    The most essential properties of ion channels for their physiologically relevant functions are ion-selective permeation and gating. Among the channel species, the potassium channel is primordial and the most ubiquitous in the biological world, and knowledge of this channel underlies the understanding of features of other ion channels. The strategy applied to studying channels changed dramatically after the crystal structure of the potassium channel was resolved. Given the abundant structural information available, we exploited the bacterial KcsA potassium channel as a simple model channel. In the postcrystal age, there are two effective frameworks with which to decipher the functional codes present in the channel structure, namely reconstitution and re-animation. Complex channel proteins are decomposed into essential functional components, and well-examined parts are rebuilt for integrating channel function in the membrane (reconstitution). Permeation and gating are dynamic operations, and one imagines the active channel by breathing life into the 'frozen' crystal (re-animation). Capturing the motion of channels at the single-molecule level is necessary to characterize the behaviour of functioning channels. Advanced techniques, including diffracted X-ray tracking, lipid bilayer methods and high-speed atomic force microscopy, have been used. Here, I present dynamic pictures of the KcsA potassium channel from the submolecular conformational changes to the supramolecular collective behaviour of channels in the membrane. These results form an integrated picture of the active channel and offer insights into the processes underlying the physiological function of the channel in the cell membrane.

  3. Ion channels in analgesia research.

    PubMed

    Rosenbaum, Tamara; Simon, Sidney A; Islas, Leon D

    2010-01-01

    Several recent techniques have allowed us to pinpoint the receptors responsible for the detection of nociceptive stimuli. Among these receptors, ion channels play a fundamental role in the recognition and transduction of stimuli that can cause pain. During the last decade, compelling evidence has been gathered on the role of the TRPV1 channel in inflammatory and neuropathic states. Activation of TRPV1 in nociceptive neurons results in the release of neuropeptides and transmitters, leading to the generation of action potentials that will be sent to higher CNS areas, where they will often be perceived as pain. Its activation will also evoke the peripheral release of pro-inflammatory compounds that may sensitize other neurons to physical, thermal, or chemical stimuli. For these reasons, and because its continuous activation causes analgesia, TRPV1 is now considered a viable drug target for clinical use in the management of pain. Using the TRPV1 channel as an example, here we describe some basic biophysical approaches used to study the properties of ion channels involved in pain and in analgesia.

  4. Vascular potassium channels in NVC.

    PubMed

    Yamada, K

    2016-01-01

    It has long been proposed that the external potassium ion ([K(+)]0) works as a potent vasodilator in the dynamic regulation of local cerebral blood flow. Astrocytes may play a central role for producing K(+) outflow possibly through calcium-activated potassium channels on the end feet, responding to a rise in the intracellular Ca(2+) concentration, which might well reflect local neuronal activity. A mild elevation of [K(+)]0 in the end feet/vascular smooth muscle space could activate Na(+)/K(+)-ATPase concomitant with inwardly rectifying potassium (Kir) channels in vascular smooth muscle cells, leading to a hyperpolarization of vascular smooth muscle and relaxation of smooth muscle actin-positive vessels. Also proposed notion is endothelial calcium-activated potassium channels and/or inwardly rectifying potassium channel-mediated hyperpolarization of vascular smooth muscle. A larger elevation of [K(+)]0, which may occur pathophysiologically in such as spreading depression or stroke, can trigger a depolarization of vascular smooth muscle cells and vasoconstriction instead. PMID:27130411

  5. Sediment budgets and channel scouring of two alpine debris-flow torrents (SE France)

    NASA Astrophysics Data System (ADS)

    Theule, J. I.; Liébault, F.; Loye, A.; Jaboyedoff, M.; Laigle, D.

    2011-12-01

    Steep mountain catchments typically experience sediment pulses from hillslopes which are stored in headwater channels and flushed out by debris-flows. Event-based sediment budget monitoring in two active debris-flow torrents in the French Alps (Manival and Réal) during a two-year period gave insights about catchment-scale sediment routing during rainfall forcings of moderate intensity. This study allowed for further investigation on channel scour relationships with gradient. The monitoring was based on intensive topographic resurveys of low- and high-order channels using different techniques (cross-section surveys with total station and high-resolution channel surveys with terrestrial and airborne laser scanning). For the Manival Torrent, sediment outputs from the main channel were obtained by a sediment trap. Two debris-flows were observed in the Manival and three in the Réal, as well as several bedload transport flow events. Sediment budget reconstitution of the five debris-flows revealed that most of the debris-flow volumes were supplied by channel scouring (always more than 92%). Bedload transport during autumn contributed to the sediment recharge of high-order channels by the deposition of large gravel wedges. This process is recognized as being fundamental for debris-flow occurrence during the subsequent spring and summer. A time shift of scour-and-fill sequences was observed between low- and high-order channels, revealing the discontinuous sediment transfer in the catchment during common flow events. A conceptual model of sediment routing for different event magnitude was proposed. Significant channel scouring by debris-flows took place in alluvial reaches. Throughout the torrent channel, the upstream channel gradient (from a local reach) is identified to play a role in debris-flow scour. Maximum scours normally occur between slopes ranging from 0.18 to 0.20 (depending on sediment availability at the time of occurrence). It is found that above this

  6. The ISC Seismic Event Bibliography

    NASA Astrophysics Data System (ADS)

    Di Giacomo, Domenico; Storchak, Dmitry

    2015-04-01

    The International Seismological Centre (ISC) is a not-for-profit organization operating in the UK for the last 50 years and producing the ISC Bulletin - the definitive worldwide summary of seismic events, both natural and anthropogenic - starting from the beginning of 20th century. Often researchers need to gather information related to specific seismic events for various reasons. To facilitate such task, in 2012 we set up a new database linking earthquakes and other seismic events in the ISC Bulletin to bibliographic records of scientific articles (mostly peer-reviewed journals) that describe those events. Such association allows users of the ISC Event Bibliography (www.isc.ac.uk/event_bibliography/index.php) to run searches for publications via a map-based web interface and, optionally, selecting scientific publications related to either specific events or events in the area of interest. Some of the greatest earthquakes were described in several hundreds of articles published over a period of few years. The journals included in our database are not limited to seismology but bring together a variety of fields in geosciences (e.g., engineering seismology, geodesy and remote sensing, tectonophysics, monitoring research, tsunami, geology, geochemistry, hydrogeology, atmospheric sciences, etc.) making this service useful in multidisciplinary studies. Usually papers dealing with large data set are not included (e.g., papers describing a seismic catalogue). Currently the ISC Event Bibliography includes over 17,000 individual publications from about 500 titles related to over 14,000 events that occurred in last 100+ years. The bibliographic records in the Event Bibliography start in the 1950s, and it is updated as new publications become available.

  7. Mode switching is the major mechanism of ligand regulation of InsP3 receptor calcium release channels.

    PubMed

    Ionescu, Lucian; White, Carl; Cheung, King-Ho; Shuai, Jianwei; Parker, Ian; Pearson, John E; Foskett, J Kevin; Mak, Don-On Daniel

    2007-12-01

    The inositol 1,4,5-trisphosphate (InsP(3)) receptor (InsP(3)R) plays a critical role in generation of complex Ca(2+) signals in many cell types. In patch clamp recordings of isolated nuclei from insect Sf9 cells, InsP(3)R channels were consistently detected with regulation by cytoplasmic InsP(3) and free Ca(2+) concentrations ([Ca(2+)](i)) very similar to that observed for vertebrate InsP(3)R. Long channel activity durations of the Sf9-InsP(3)R have now enabled identification of a novel aspect of InsP(3)R gating: modal gating. Using a novel algorithm to analyze channel modal gating kinetics, InsP(3)R gating can be separated into three distinct modes: a low activity mode, a fast kinetic mode, and a burst mode with channel open probability (P(o)) within each mode of 0.007 +/- 0.002, 0.24 +/- 0.03, and 0.85 +/- 0.02, respectively. Channels reside in each mode for long periods (tens of opening and closing events), and transitions between modes can be discerned with high resolution (within two channel opening and closing events). Remarkably, regulation of channel gating by [Ca(2+)](i) and [InsP(3)] does not substantially alter channel P(o) within a mode. Instead, [Ca(2+)](i) and [InsP(3)] affect overall channel P(o) primarily by changing the relative probability of the channel being in each mode, especially the high and low P(o) modes. This novel observation therefore reveals modal switching as the major mechanism of physiological regulation of InsP(3)R channel activity, with implications for the kinetics of Ca(2+) release events in cells.

  8. Higgs in bosonic channels (CMS)

    NASA Astrophysics Data System (ADS)

    Gori, Valentina

    2015-05-01

    The main Higgs boson decays into bosonic channels will be considered, presenting and discussing results from the latest reprocessing of data collected by the CMS experiment at the LHC, using the full dataset recorded at centre-of-mass energies of 7 and 8 TeV. For this purpose, results from the final Run-I papers for the H → ZZ → 4ℓ, H → γγ and H → WW analyses are presented, focusing on the Higgs boson properties, like the mass, the signal strenght, the couplings to fermions and vector bosons, the spin and parity properties. Furthermore, the Higgs boson width measurement exploiting the on-shell versus the off-shell cross section (in the H → ZZ → 4ℓ and H → ZZ → 2ℓ2ν decay channels) will be shown. All the investigated properties result to be fully consistent with the SM predictions: the signal strength and the signal strength modifiers are consistent with unity in all the bosonic channels considered; the hypothesis of a scalar particle is strongly favored, against the pseudoscalar or the vector/pseudovector or the spin-2 boson hypotheses (all excluded at 99% CL or higher in the H → ZZ → 4ℓ channel). The Higgs boson mass measurement from the combination of H → ZZ → 4ℓ and H → γγ channels gives a value mH = 125.03+0.26-0.27 (stat.) +0.13-0.15 (syst.). An upper limit ΓH < 22 MeV can be put on the Higgs boson width thanks to the new indirect method.

  9. Regularly timed events amid chaos

    NASA Astrophysics Data System (ADS)

    Blakely, Jonathan N.; Cooper, Roy M.; Corron, Ned J.

    2015-11-01

    We show rigorously that the solutions of a class of chaotic oscillators are characterized by regularly timed events in which the derivative of the solution is instantaneously zero. The perfect regularity of these events is in stark contrast with the well-known unpredictability of chaos. We explore some consequences of these regularly timed events through experiments using chaotic electronic circuits. First, we show that a feedback loop can be implemented to phase lock the regularly timed events to a periodic external signal. In this arrangement the external signal regulates the timing of the chaotic signal but does not strictly lock its phase. That is, phase slips of the chaotic oscillation persist without disturbing timing of the regular events. Second, we couple the regularly timed events of one chaotic oscillator to those of another. A state of synchronization is observed where the oscillators exhibit synchronized regular events while their chaotic amplitudes and phases evolve independently. Finally, we add additional coupling to synchronize the amplitudes, as well, however in the opposite direction illustrating the independence of the amplitudes from the regularly timed events.

  10. Eventos de Junio (June Events).

    ERIC Educational Resources Information Center

    Pla, Myrna; Toro, Leonor

    Written in Spanish, this booklet contains brief information on six June events celebrated by Puerto Ricans: Nathan Hale, Dia de la Bandera (Flag Day), Francisco Oller, Dia de los Padres (Father's Day), Fiesta de San Juan Bautista, and school graduation. Designed for teachers, the booklet includes a listing of 16 historical events occurring in…

  11. Maternal Talk About Disappearance Events.

    ERIC Educational Resources Information Center

    Goldfield, Beverly A.

    1995-01-01

    Examined maternal talk about events regarding hidden, missing, or absent persons or objects, and the relationship of maternal language to children's acquisition of words for disappearance, among 12 mother-infant pairs. Results found that infants who had acquired "gone" and similar terms experienced more disappearance events than children who had…

  12. Crystal structure of a heterotetrameric NMDA receptor ion channel.

    PubMed

    Karakas, Erkan; Furukawa, Hiro

    2014-05-30

    N-Methyl-D-aspartate (NMDA) receptors belong to the family of ionotropic glutamate receptors, which mediate most excitatory synaptic transmission in mammalian brains. Calcium permeation triggered by activation of NMDA receptors is the pivotal event for initiation of neuronal plasticity. Here, we show the crystal structure of the intact heterotetrameric GluN1-GluN2B NMDA receptor ion channel at 4 angstroms. The NMDA receptors are arranged as a dimer of GluN1-GluN2B heterodimers with the twofold symmetry axis running through the entire molecule composed of an amino terminal domain (ATD), a ligand-binding domain (LBD), and a transmembrane domain (TMD). The ATD and LBD are much more highly packed in the NMDA receptors than non-NMDA receptors, which may explain why ATD regulates ion channel activity in NMDA receptors but not in non-NMDA receptors.

  13. Channel erosion surveys along the TAPS route, Alaska, 1977

    USGS Publications Warehouse

    Loeffler, Robert M.; Childers, Joseph M.

    1977-01-01

    Channel surveys were made along the trans-Alaska pipeline system (TAPS) route during 1977 at the same 28 sites that were studied in 1976. In addition, a new site at pipeline mile 22 near Deadhorse (alignment No 134) along the Sagavanirktok River was put under surveillance. Except for changes wrought by the completion of construction, most of the sites showed very little change. Significant events include virtual completion of all construction activities along the pipeline, the pipeline startup , and the breakup flood along the Sagavanirktok River which breached many river-training structures. In general, 1977 saw heavy flooding on streams draining the north and south slopes of the Brooks Range and only moderate flooding on streams further south. Aerial photogrammetric surveys were used again in 1977 on the same seven sites as in 1976. Results document the applicability of the method for channel erosion studies. (Woodard-USGS)

  14. Can rice field channels contribute to biodiversity conservation in Southern Brazilian wetlands?

    PubMed

    Maltchik, Leonardo; Rolon, Ana Silvia; Stenert, Cristina; Machado, Iberê Farina; Rocha, Odete

    2011-12-01

    Conservation of species in agroecosystems has attracted attention. Irrigation channels can improve habitats and offer conditions for freshwater species conservation. Two questions from biodiversity conservation point of view are: 1) Can the irrigated channels maintain a rich diversity of macrophytes, macroinvertebrates and amphibians over the cultivation cycle? 2) Do richness, abundance and composition of aquatic species change over the rice cultivation cycle? For this, a set of four rice field channels was randomly selected in Southern Brazilian wetlands. In each channel, six sample collection events were carried out over the rice cultivation cycle (June 2005 to June 2006). A total of 160 taxa were identified in irrigated channels, including 59 macrophyte species, 91 taxa of macroinvertebrate and 10 amphibian species. The richness and abundance of macrophytes, macroinvertebrates and amphibians did not change significantly over the rice cultivation cycle. However, the species composition of these groups in the irrigation channels varied between uncultivated and cultivated periods. Our results showed that the species diversity found in the irrigation channels, together with the permanence of water enables these man-made aquatic networks to function as important systems that can contribute to the conservation of biodiversity in regions where the wetlands were converted into rice fields. The conservation of the species in agriculture, such as rice field channels, may be an important alternative for biodiversity conservation in Southern Brazil, where more than 90% of wetland systems have already been lost and the remaining ones are still at high risk due to the expansion of rice production.

  15. Identification of new deep sea sinuous channels in the eastern Arabian Sea.

    PubMed

    Mishra, Ravi; Pandey, D K; Ramesh, Prerna; Clift, Peter D

    2016-01-01

    Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geological record. The Indus Fan is the second largest modern submarine fan, having a well-developed active canyon and deep sea channel system. Previous studies from the upper Indus Fan have reported several active channel systems. In the present study, deep sea channel systems were identified within the middle Indus Fan using high resolution multibeam bathymetric data. Prominent morphological features within the survey block include the Raman Seamount and Laxmi Ridge. The origin of the newly discovered channels in the middle fan has been inferred using medium resolution satellite bathymetry data. Interpretation of new data shows that the highly sinuous deep sea channel systems also extend to the east of Laxmi Ridge, as well as to the west of Laxmi Ridge, as previously reported. A decrease in sinuosity southward can be attributed to the morphological constraints imposed by the elevated features. These findings have significance in determining the pathways for active sediment transport systems, as well as their source characterization. The geometry suggests a series of punctuated avulsion events leading to the present array of disconnected channels. Such channels have affected the Laxmi Basin since the Pliocene and are responsible for reworking older fan sediments, resulting in loss of the original erosional signature supplied from the river mouth. This implies that distal fan sediments have experienced significant signal shredding and may not represent the erosion and weathering conditions within the onshore basin at the time of sedimentation.

  16. Dopamine modulates the kinetics of ion channels gated by excitatory amino acids in retinal horizontal cells.

    PubMed Central

    Knapp, A G; Schmidt, K F; Dowling, J E

    1990-01-01

    Upon exposure to dopamine, cultured teleost retinal horizontal cells become more responsive to the putative photoreceptor neurotransmitter L-glutamate and to its analog kainate. We have recorded unitary and whole-cell currents to determine the mechanism by which dopamine enhances ion channels activated by these agents. In single-channel recordings from cell-attached patches with agonist in the patch pipette, the frequency of 5- to 10-pS unitary events, but not their amplitude, increased by as much as 150% after application of dopamine to the rest of the cell. The duration of channel openings also increased somewhat, by 20-30%. In whole-cell experiments, agonists with and without dopamine were applied to voltage-clamped horizontal cells by slow superfusion. Analysis of whole-cell current variance as a function of mean current indicated that dopamine increased the probability of channel opening for a give agonist concentration without changing the amount of current passed by an individual channel. For kainate, noise analysis additionally demonstrated that dopamine did not alter the number of functional channels. Dopamine also increased a slow spectral component of whole-cell currents elicited by kainate or glutamate, suggesting a change in the open-time kinetics of the channels. This effect was more pronounced for currents induced by glutamate than for those induced by kainate. We conclude that dopamine potentiates the activity of horizontal cell glutamate receptors by altering the kinetics of the ion channel to favor the open state. PMID:1689053

  17. Identification of new deep sea sinuous channels in the eastern Arabian Sea.

    PubMed

    Mishra, Ravi; Pandey, D K; Ramesh, Prerna; Clift, Peter D

    2016-01-01

    Deep sea channel systems are recognized in most submarine fans worldwide as well as in the geological record. The Indus Fan is the second largest modern submarine fan, having a well-developed active canyon and deep sea channel system. Previous studies from the upper Indus Fan have reported several active channel systems. In the present study, deep sea channel systems were identified within the middle Indus Fan using high resolution multibeam bathymetric data. Prominent morphological features within the survey block include the Raman Seamount and Laxmi Ridge. The origin of the newly discovered channels in the middle fan has been inferred using medium resolution satellite bathymetry data. Interpretation of new data shows that the highly sinuous deep sea channel systems also extend to the east of Laxmi Ridge, as well as to the west of Laxmi Ridge, as previously reported. A decrease in sinuosity southward can be attributed to the morphological constraints imposed by the elevated features. These findings have significance in determining the pathways for active sediment transport systems, as well as their source characterization. The geometry suggests a series of punctuated avulsion events leading to the present array of disconnected channels. Such channels have affected the Laxmi Basin since the Pliocene and are responsible for reworking older fan sediments, resulting in loss of the original erosional signature supplied from the river mouth. This implies that distal fan sediments have experienced significant signal shredding and may not represent the erosion and weathering conditions within the onshore basin at the time of sedimentation. PMID:27386293

  18. Strategy for evaluating channeling in the carbonate bedrock at Smithville, Ontario

    SciTech Connect

    Worthington, S.R.H.; Ford, D.C.

    1997-12-31

    Groundwater flow through carbonates typically results in a network of solutionally-enlarged channels (or conduits). These transmit much of the flow yet occupy only a small fraction of the void space in the aquifer. Since boreholes are unlikely to intersect the channels, standard aquifer tests are unable to characterize channel flow, and a novel strategy is needed. Four strategies are being used in the dolostone aquifer at Smithville to characterize channeling. First, passive in situ monitoring of water level, temperature and electrical conductivity is being used to show which boreholes show the rapid response to storm events that is characteristic of channeling. Second, cross-borehole pressure pulse and tracer tests reveal fracture connectivity and flow velocity. Third, two analog sites are being used for comparison. One is a nearby quarry where channeling is indicated by point discharges in the quarry face. The other is in a well-developed karst area, where aquifer test data is available for comparison with Smithville. The final strategy is to add channel flow to the existing FRAC3DVS model, and to compare simulations with and without channeling to existing aquifer test data.

  19. Event group importance measures for top event frequency analyses

    SciTech Connect

    1995-07-31

    Three traditional importance measures, risk reduction, partial derivative, nd variance reduction, have been extended to permit analyses of the relative importance of groups of underlying failure rates to the frequencies of resulting top events. The partial derivative importance measure was extended by assessing the contribution of a group of events to the gradient of the top event frequency. Given the moments of the distributions that characterize the uncertainties in the underlying failure rates, the expectation values of the top event frequency, its variance, and all of the new group importance measures can be quantified exactly for two familiar cases: (1) when all underlying failure rates are presumed independent, and (2) when pairs of failure rates based on common data are treated as being equal (totally correlated). In these cases, the new importance measures, which can also be applied to assess the importance of individual events, obviate the need for Monte Carlo sampling. The event group importance measures are illustrated using a small example problem and demonstrated by applications made as part of a major reactor facility risk assessment. These illustrations and applications indicate both the utility and the versatility of the event group importance measures.

  20. Mid-Carboniferous eustatic event

    SciTech Connect

    Saunders, W.B.; Ramsbottom, W.H.C.

    1986-03-01

    Stratigraphic and paleontologic evidence from mid-Carboniferous (Namurian) basin and shelf successions in widely scattered parts of the world indicates that a major eustatic event occurred about 330 Ma. The event began with a regression that is recorded in most shelf sequences, the regression was followed by a brief transgression about 328 Ma, and the event ended with a transgression that flooded large shelf areas about 325 Ma. The Mississippian-Pennsylvanian unconformity in North America is a well-known product of this event, but equally prominent and contemporaneous unconformity surfaces are also present in Europe, North Africa, and elsewhere. The event is believed to have caused numerous extinctions, and it resulted in marked fluctuations in faunal diversity. 94 references, 2 figures.

  1. Extinction events can accelerate evolution.

    PubMed

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific in the long term.

  2. Extinction Events Can Accelerate Evolution

    PubMed Central

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific in the long term. PMID:26266804

  3. Hydraulic and Morphodynamic Characteristics of Submarine Channel Confluences

    NASA Astrophysics Data System (ADS)

    Ismail, H.; Viparelli, E.; Ezz, H.; Imran, J.

    2013-12-01

    Submarine channel systems are receiving increased attention recently for their potential in transporting and depositing hydrocarbons via turbidity currents into the deep ocean. In order to better predict the locations of hydrocarbon reserves, a more complete understanding of the hydraulic behavior of flows within the channels is necessary. Past field observations have shown that submarine channels have straight and meandering reaches, along with junctions in channel systems; flows in the submarine environment (i.e. density currents) may propagate as a single pulse or as a sustained flow over a prolonged period. This work aims to further the understanding of submarine channel systems by focusing on the hydraulic behavior of submarine channel confluences due to both sudden release (i.e. pulse events) and sustained flows. The associated morphodynamic consequences at and near the confluence are also assessed as they relate to the observed hydraulic conditions. Observational goals include comparisons to heavily studied characteristics of subaerial river channel confluences. These include flow separation zones, helical flow cells, existence of vertical shear layers, avalanche faces upstream of the junction, and deep central scours in the junction. For this investigation, a physical model was built to simulate a 45 degree submarine channel junction with an erodible bed in which two fully conservative density currents are released in each upstream reach and allowed to collide before creating a single combined current in the downstream reach. The pulse events focused on the head of the density currents and were simulated using a lock-exchange mechanism in which a fixed volume of salt water was locked in each upstream reach of the flume before being suddenly released into the ambient water downstream. HD images were used to obtain 1D velocity both up- and down-stream of the junction, and bathymetry measurements were obtained using an ultrasonic probe after each experiment

  4. A model of channel response in disturbed alluvial channels

    USGS Publications Warehouse

    Simon, A.

    1989-01-01

    Dredging and straightening of alluvial channels between 1959 and 1978 in West Tennessee caused a series of morphologic changes along modified reaches and tributary streams. Degradation occurred for 10 to 15 years at sites upstream of the area of maximum disturbance and lowered bed-levels by as much as 6.1 m. Following degradation, reaches upstream of the area of maximum disturbance experienced a secondary aggradation phase in response to excessive incision and gradient reduction. -from Author

  5. Effects of Concrete Channels on Stream Biogeochemistry, Maryland Coastal Plain

    NASA Astrophysics Data System (ADS)

    Prestegaard, K. L.; Gilbert, L.; Phemister, K.

    2005-05-01

    In the 1950's and 60's, extensive networks of cement-lined channels were built in suburban watersheds near Washington, D.C. to convey storm water to downstream locations. These cement-lined stream channels limit interactions between surface and groundwater and they provide sources of alkalinity in Maryland Coastal Plain watersheds that normally have low alkalinity. This project was designed to 1) compare base flow water chemistry in headwater reaches of urban and non-urban streams, and 2) to evaluate downstream changes in water chemistry in channelized urban streams in comparison with non-urban reference streams. During a drought year, headwater streams in both urban and non-urban sites had significant concentrations of Fe(II) that were discharged from groundwater sources and rapidly oxidized by iron-oxidizing bacteria. During a wet year, the concentrations of Fe(II) were higher in headwater urban streams than in the non-urban streams. This suggests that impervious surfaces in headwater urban watersheds prevent the recharge of oxygen-rich waters during storm events, which maintains iron-rich groundwater discharge to the stream. Downstream changes in water chemistry are prominent in cement-lined urban channels because they are associated with distinctive microbial communities. The headwater zones of channelized streams are dominated by iron-ozidizing bacteria, that are replaced downstream by manganese-oxidizing zones, and replaced further downstream by biofilms dominated by photosynthesizing cyanobacteria. The reaches dominated by cyanobacteria exhibit diurnal changes in pH due to uptake of CO2 for photosynthesis. Diurnal changes range from 7.5 to 8.8 in the summer months to 7.0 to 7.5 in the cooler months, indicating both the impact of photosynthesis and the additional source of alkalinity provided by concrete. The dissolved oxygen, pH, and other characteristics of tributaries dominated by cyanobacteria are similar to the water chemistry characteristics observed in

  6. "Hammer" events, neutrino energies, and nucleon-nucleon correlations

    NASA Astrophysics Data System (ADS)

    Weinstein, L. B.; Hen, O.; Piasetzky, Eli

    2016-10-01

    are less similar to the observed events. Conclusions: ArgoNeut hammer events can be described by a simple pion production and reabsorption model. The hammer events that will be measured in MicroBooNE can be used to determine the incident neutrino energy but not to learn about SRC. We suggest that this reaction channel could be used for neutrino oscillation experiments to complement other channels with higher statistics but different systematic uncertainties.

  7. Sodium channel slow inactivation interferes with open channel block

    PubMed Central

    Hampl, Martin; Eberhardt, Esther; O’Reilly, Andrias O.; Lampert, Angelika

    2016-01-01

    Mutations in the voltage-gated sodium channel Nav1.7 are linked to inherited pain syndromes such as erythromelalgia (IEM) and paroxysmal extreme pain disorder (PEPD). PEPD mutations impair Nav1.7 fast inactivation and increase persistent currents. PEPD mutations also increase resurgent currents, which involve the voltage-dependent release of an open channel blocker. In contrast, IEM mutations, whenever tested, leave resurgent currents unchanged. Accordingly, the IEM deletion mutation L955 (ΔL955) fails to produce resurgent currents despite enhanced persistent currents, which have hitherto been considered a prerequisite for resurgent currents. Additionally, ΔL955 exhibits a prominent enhancement of slow inactivation (SI). We introduced mutations into Nav1.7 and Nav1.6 that either enhance or impair SI in order to investigate their effects on resurgent currents. Our results show that enhanced SI is accompanied by impaired resurgent currents, which suggests that SI may interfere with open-channel block. PMID:27174182

  8. Clofilium inhibits Slick and Slack potassium channels

    PubMed Central

    de los Angeles Tejada, Maria; Stolpe, Kathleen; Meinild, Anne-Kristine; Klaerke, Dan A

    2012-01-01

    Slick and Slack high-conductance potassium channels have been recently discovered, and are found in the central nervous system and in the heart. Both channels are activated by Na+ and Cl−, and Slick channels are also inhibited by adenosine triphospate (ATP). An important role of setting the resting membrane potential and controlling the basal excitability of neurons has been suggested for these channels. In addition, no specific blockers for these channels are known up to the present. With the purpose of studying the pharmacological characteristics of Slick and Slack channels, the effects of exposure to the antiarrhythmic compound clofilium were evaluated. Clofilium was able to modulate the activity of Slick and Slack channels effectively, with a stronger effect on Slack than Slick channels. In order to evaluate the pharmacological behavior of Slick and Slack channels further, 38 commonly used potassium channel blockers were tested. Screening of these compounds did not reveal any modulators of Slick and Slack channels, except for clofilium. The present study provides a first approach towards elucidating the pharmacological characteristics of Slick and Slack channels and could be the basis for future studies aimed at developing potent and specific blockers and activators for these channels. PMID:23271893

  9. Efficient massively parallel simulation of dynamic channel assignment schemes for wireless cellular communications

    NASA Technical Reports Server (NTRS)

    Greenberg, Albert G.; Lubachevsky, Boris D.; Nicol, David M.; Wright, Paul E.

    1994-01-01

    Fast, efficient parallel algorithms are presented for discrete event simulations of dynamic channel assignment schemes for wireless cellular communication networks. The driving events are call arrivals and departures, in continuous time, to cells geographically distributed across the service area. A dynamic channel assignment scheme decides which call arrivals to accept, and which channels to allocate to the accepted calls, attempting to minimize call blocking while ensuring co-channel interference is tolerably low. Specifically, the scheme ensures that the same channel is used concurrently at different cells only if the pairwise distances between those cells are sufficiently large. Much of the complexity of the system comes from ensuring this separation. The network is modeled as a system of interacting continuous time automata, each corresponding to a cell. To simulate the model, conservative methods are used; i.e., methods in which no errors occur in the course of the simulation and so no rollback or relaxation is needed. Implemented on a 16K processor MasPar MP-1, an elegant and simple technique provides speedups of about 15 times over an optimized serial simulation running on a high speed workstation. A drawback of this technique, typical of conservative methods, is that processor utilization is rather low. To overcome this, new methods were developed that exploit slackness in event dependencies over short intervals of time, thereby raising the utilization to above 50 percent and the speedup over the optimized serial code to about 120 times.

  10. Hydrological response of an Alpine catchment to rainfall and snowmelt events

    NASA Astrophysics Data System (ADS)

    Penna, D.; van Meerveld, H. J.; Zuecco, G.; Dalla Fontana, G.; Borga, M.

    2016-06-01

    Alpine catchments are important sources of fresh water but compared to lower altitude catchments our understanding of the hydrological functioning of these catchments during rainfall and snowmelt events is still limited. The objectives of this study were i) to identify the dominant runoff generation mechanisms in the 0.14-km2 Bridge Creek Catchment in the Italian Dolomites during nine rainfall-runoff events and six snowmelt-runoff events in spring, summer and autumn of 2010-2012; and ii) to assess the effect of the selection of the pre-event water sample on the isotope hydrograph separation results. The isotopic composition of the pre-event water was determined by either a stream water sample taken prior to the event or the average of 19 stream water samples taken during baseflow conditions. The hydrograph separation results for the two methods were very similar for the rainfall events but differed for the snowmelt events. Average event water contributions ranged between 4% and 19% or 2% and 20% of the total runoff during rainfall events, and between 7% and 25% or 9% and 38% during snowmelt events, depending on the method used to determine the isotopic composition of pre-event water. Event water contributions were important during large rainfall events, intense rainfall events and late in the snowmelt season, with maximum event water contributions up to 37% and 46%, depending on the method used for determining the pre-event water composition. The electrical conductivity of stream water tended to first decrease and reach a minimum before peak streamflow and then to increase above pre-event values. The results of this study suggest that during dry conditions, direct channel precipitation and overland flow from the permanently saturated part of the riparian zone dominated the runoff response, with limited contributions of riparian or hillslope groundwater. During wet or very wet conditions (large rainfall events or peak snowmelt), saturation overland flow increased

  11. Novel method of channel estimation for WCDMA downlink

    NASA Astrophysics Data System (ADS)

    Sheng, Bin; You, XiaoHu

    2001-10-01

    A novel scheme for channel estimation is proposed in this paper for WCDMA Downlink where a pilot channel is simultaneously transmitted with a dada traffic channel. The proposed scheme exploits channel information in both pilot and data traffic channels by combining channel estimates from these two channels. It is demonstrated by computer simulations that the performance of the Rake receiver is improved obviously.

  12. Dynamic Triggering of Microseismic Events

    NASA Astrophysics Data System (ADS)

    Lu, H.; Van der Baan, M.

    2015-12-01

    Microseismic events are commonly recorded during hydraulic fracturing experiments. In microseismic interpretations, each event is often regarded as independent and uncorrelated to neighboring ones. In reality, both the rock deformation (static stresses) and transient wave motion (dynamic stresses) associated with microseismic events add to the stress field together with the external loading (fluid injection). We believe the resulting static and dynamic stress perturbations will influence both the timing and spatial evolution of the microseismic cloud. We study the dynamic triggering of microseismicity using numerical simulations of a biaxial deformation test by means of a bonded particle method (Potyondy and Cundall, 2004), where crack development can be tracked and analyzed independently. Our methodology is to compare the stress changes due to one specific event with the occurrence of the next few events in the numerical simulations. In addition, we compute the dynamic stress perturbations for recorded large events analytically given their (non-double couple) failure mechanisms. Our results show that cracks following a major event tend to form in zones affected by the dynamic stresses by promoting new failure in areas that are critically stressed. This confirms that dynamic triggering during hydraulic fracturing operations but also larger scale seismicity is likely. It also demonstrates the often complex interplay between the dynamic and static stress changes and their effect on the temporal and spatial evolution of rock deformation at all scales.

  13. Channel estimation in DCT-based OFDM.

    PubMed

    Wang, Yulin; Zhang, Gengxin; Xie, Zhidong; Hu, Jing

    2014-01-01

    This paper derives the channel estimation of a discrete cosine transform-(DCT-) based orthogonal frequency-division multiplexing (OFDM) system over a frequency-selective multipath fading channel. Channel estimation has been proved to improve system throughput and performance by allowing for coherent demodulation. Pilot-aided methods are traditionally used to learn the channel response. Least square (LS) and mean square error estimators (MMSE) are investigated. We also study a compressed sensing (CS) based channel estimation, which takes the sparse property of wireless channel into account. Simulation results have shown that the CS based channel estimation is expected to have better performance than LS. However MMSE can achieve optimal performance because of prior knowledge of the channel statistic.

  14. Process tomography for unitary quantum channels

    SciTech Connect

    Gutoski, Gus; Johnston, Nathaniel

    2014-03-15

    We study the number of measurements required for quantum process tomography under prior information, such as a promise that the unknown channel is unitary. We introduce the notion of an interactive observable and we show that any unitary channel acting on a d-level quantum system can be uniquely identified among all other channels (unitary or otherwise) with only O(d{sup 2}) interactive observables, as opposed to the O(d{sup 4}) required for tomography of arbitrary channels. This result generalizes to the problem of identifying channels with at most q Kraus operators, and slight improvements can be obtained if we wish to identify such a channel only among unital channels or among other channels with q Kraus operators. These results are proven via explicit construction of large subspaces of Hermitian matrices with various conditions on rank, eigenvalues, and partial trace. Our constructions are built upon various forms of totally nonsingular matrices.

  15. Bandwidth efficient coding for fading channels - Code construction and performance analysis

    NASA Technical Reports Server (NTRS)

    Schlegel, Christian; Costello, Daniel J., Jr.

    1989-01-01

    The authors apply a general method of bounding the event error probability of trellis-coded modulation schemes to fading channels and use the effective length and the minimum-squared-product distance to replace the minimum-free-squared-Euclidean distance as code design parameters for Rayleigh and Rician fading channels with a substantial multipath component. They present 8-PSK trellis codes specifically constructed for fading channels that outperform equivalent codes designed for the additive white Gaussian noise channel when v is greater than or equal to 5. For quasiregular trellis codes there exists an efficient algorithm for evaluating event error probability, and numerical results on Pe which demonstrate the importance of the effective length as a code design parameter for fading channels with or without side information have been obtained. This is consistent with the case for binary signaling, where the Hamming distance remains the best code design parameter for fading channels. The authors show that the use of Reed-Solomon block codes with expanded signal sets becomes interesting only for large values of E(s)/N(0), where they begin to outperform trellis codes.

  16. TARGET: A multi-channel digitizer chip for very-high-energy gamma-ray telescopes

    SciTech Connect

    Bechtol, K.; Funk, S.; Okumura, A.; Ruckman, L.; Simons, A.; Tajima, H.; Vandenbroucke, J.; Varner, G.; /Hawaii U.

    2011-08-11

    The next-generation very-high-energy (VHE) gamma-ray observatory, the Cherenkov Telescope Array, will feature dozens of imaging atmospheric Cherenkov telescopes (IACTs), each with thousands of pixels of photosensors. To be affordable and reliable, reading out such a mega-channel array requires event recording technology that is highly integrated and modular, with a low cost per channel. We present the design and performance of a chip targeted to this application: the TeV Array Readout with GSa/s sampling and Event Trigger (TARGET). This application-specific integrated circuit (ASIC) has 16 parallel input channels, a 4096-sample buffer for each channel, adjustable input termination, self-trigger functionality, and tight window-selected readout. We report the performance of TARGET in terms of sampling frequency, power consumption, dynamic range, current-mode gain, analog bandwidth, and cross talk. The large number of channels per chip allows a low cost per channel ($10 to $20 including front-end and back-end electronics but not including photosensors) to be achieved with a TARGET-based IACT readout system. In addition to basic performance parameters of the TARGET chip itself, we present a camera module prototype as well as a second-generation chip (TARGET 2), both of which have been produced.

  17. Membrane lipid modulations remove divalent open channel block from TRP-like and NMDA channels.

    PubMed

    Parnas, Moshe; Katz, Ben; Lev, Shaya; Tzarfaty, Vered; Dadon, Daniela; Gordon-Shaag, Ariela; Metzner, Henry; Yaka, Rami; Minke, Baruch

    2009-02-25

    Open channel block is a process in which ions bound to the inside of a channel pore block the flow of ions through that channel. Repulsion of the blocking ions by depolarization is a known mechanism of open channel block removal. For the NMDA channel, this mechanism is necessary for channel activation and is involved in neuronal plasticity. Several types of transient receptor potential (TRP) channels, including the Drosophila TRP and TRP-like (TRPL) channels, also exhibit open channel block. Therefore, removal of open channel block is necessary for the production of the physiological response to light. Because there is no membrane depolarization before the light response develops, it is not clear how the open channel block is removed, an essential step for the production of a robust light response under physiological conditions. Here we present a novel mechanism to alleviate open channel block in the absence of depolarization by membrane lipid modulations. The results of this study show open channel block removal by membrane lipid modulations in both TRPL and NMDA channels of the photoreceptor cells and CA1 hippocampal neurons, respectively. Removal of open channel block is characterized by an increase in the passage-rate of the blocking cations through the channel pore. We propose that the profound effect of membrane lipid modulations on open channel block alleviation, allows the productions of a robust current in response to light in the absence of depolarization.

  18. Tuning Photochromic Ion Channel Blockers

    PubMed Central

    2011-01-01

    Photochromic channel blockers provide a conceptually simple and convenient way to modulate neuronal activity with light. We have recently described a family of azobenzenes that function as tonic blockers of Kv channels but require UV-A light to unblock and need to be actively switched by toggling between two different wavelengths. We now introduce red-shifted compounds that fully operate in the visible region of the spectrum and quickly turn themselves off in the dark. Furthermore, we have developed a version that does not block effectively in the dark-adapted state, can be switched to a blocking state with blue light, and reverts to the inactive state automatically. Photochromic blockers of this type could be useful for the photopharmacological control of neuronal activity under mild conditions. PMID:22860175

  19. Ion channels meet auxin action.

    PubMed

    Fuchs, I; Philippar, K; Hedrich, R

    2006-05-01

    The regulation of cell division and elongation in plants is accomplished by the action of different phytohormones. Auxin as one of these growth regulators is known to stimulate cell elongation growth in the aerial parts of the plant. Here, auxin enhances cell enlargement by increasing the extensibility of the cell wall and by facilitating the uptake of osmolytes such as potassium ions into the cell. Starting in the late 1990s, the auxin regulation of ion channels mediating K+ import into the cell has been studied in great detail. In this article we will focus on the molecular mechanisms underlying the modulation of K+ transport by auxin and present a model to explain how the regulation of K+ channels is involved in auxin-induced cell elongation growth. PMID:16807828

  20. GMSK co-channel demodulation

    NASA Astrophysics Data System (ADS)

    Nelson, D. J.; Hopkins, J. R.

    2009-08-01

    Gaussian Minimum Shift Keying (GMSK) is a modulation method used by GSM phone networks and the Automatic Identification System (AIS) used by commercial ships. Typically these systems transmit data in short bursts and accomodate a large number of users by time, frequency and power management. Co-channel interference is not a problem unless the system is heavily loaded. This system load is a function of the density of users and the footprint of the receiver. We consider the problem of demodulation of burst GMSK signals in the presence of severe noise and co-channel interference. We further examine the problem of signal detection and blind estimation and tracking of all of the parameters required in the demodulation process. These parameters include carrier frequency, carrier phase, baud rate, baud phase, modulation index and the start and duration of the signal.

  1. Techniques for multilayer channel routing

    NASA Astrophysics Data System (ADS)

    Braun, Douglas; Burns, Jeffrey L.; Romeo, Fabio; Sangiovanni-Vincentelli, Alberto; Mayaram, Kartikeya

    1988-06-01

    The techniques described have been implemented in a multilayer channel router called Chameleon. Chameleon consists of two stages: a partitioner and a detailed router. The partitioner divides the problem into two-layer and three-layer subproblems such that global channel area is minimized. The detailed router then implements the connections using generalizations of the algorithms used in YACR2. In particular, a three-dimensional maze router is used for the vertical connections; this methodology is effective even when cycle constraints are present. Chameleon has produced optimal results on a wide range of industrial and academic examples for a variety of layer and pitch combinations, and can handle a variety of technology constraints.

  2. Characteristics pertinent to propagation of pulsating pressure in the channels of turbine machines

    NASA Astrophysics Data System (ADS)

    Liu, Hong; Chen, Zuoyi

    2007-01-01

    A new model describing the propagation of the pressure pulsations in the intricately shaped channels of turbine machines is presented. The proposed model was successfully used to analyze two emergency events: a failure of a steam turbine’s cast diaphragm and a failure of a rocket engine’s oxygen pump booster stage.

  3. A Scientist or Salesman? Identity Construction through Referent Honorifics on a Japanese Shopping Channel Program

    ERIC Educational Resources Information Center

    Cook, Haruko Minegishi

    2013-01-01

    This paper explores how referent honorifics contribute to identity construction on a Japanese TV shopping channel program. Drawing on Ochs' twostep model of indexicality (1993, 1996) and Agah's proposal (1993) that honorifics are not directly linked to social status but index a "relative position within events of discursive…

  4. Top channel for early supersymmetry discovery at the LHC

    SciTech Connect

    Kane, Gordon L.; Kuflik, Eric; Lu, Ran; Wang, Lian-Tao

    2011-11-01

    Arguably the best-motivated channel for early LHC discovery is events including a high multiplicity of third generation quarks, such as four top quarks. For example generic string theories compactified to four dimensions with stabilized moduli typically have light gluinos with large branching ratios to t- and b-quarks. We analyze signals and background at 7 TeV LHC energy for 1 fb{sup -1} integrated luminosity, suggesting a reach for gluinos of about 650 GeV. A non-standard model signal from counting b-jets and leptons is robust, and provides information on the gluino mass, cross section, and spin.

  5. Ion channels, phosphorylation and mammalian sperm capacitation.

    PubMed

    Visconti, Pablo E; Krapf, Dario; de la Vega-Beltrán, José Luis; Acevedo, Juan José; Darszon, Alberto

    2011-05-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  6. Ion channels, phosphorylation and mammalian sperm capacitation

    PubMed Central

    Visconti, Pablo E; Krapf, Dario; de la Vega-Beltrán, José Luis; Acevedo, Juan José; Darszon, Alberto

    2011-01-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies. PMID:21540868

  7. Do the coarsest bed fractions and stream power record contemporary trends in steep headwater channels?

    NASA Astrophysics Data System (ADS)

    Galia, Tomáš; Škarpich, Václav

    2016-11-01

    Three stream channels that were devoid of evidence of past debris flows and one headwater channel that contained debris flow deposits in the flysch western Carpathians, Czech Republic were selected to test relationships between in-channel processes, bed sediments, and unit stream power calculated for bankfull and Q20 flows. Contemporary depositional or erosional trends in the examined headwaters were linked with bed sediments that were represented by the coarsest cobble and boulder fraction with a mean calculated from the five largest particles. The downstream trends of the unit stream power were derived for a bankfull discharge and a well-documented 20-year flood event. In addition, the flow competences during the discharges were calculated using indirect bedload transport measurements. Downstream fining of the cobble and boulder fraction was observed in all of the studied headwaters, and unique downstream variations of the unit stream power were calculated for the longitudinal profiles. The single-thread streams that were devoid of evidence of debris flow events exhibited direct relations between the coarsest sediment size and the unit stream power, especially as calculated for the 20-year flood event and for erosional/depositional trends of the channel. The downstream coarsening of the bed material that was accompanied by an increase in the unit stream power was usually observed in the case of deeply incised (> 0.5 m above the assumed bankfull depth) channel reaches. The calculated competence of the 20-year flow was up to twofold higher than that required to entrain the largest bed particle diameters in those channel reaches, and even the bankfull flow was potentially capable of transporting the coarsest bed particles in certain of the reaches. On the other hand, some depositional channel reaches evidently led to the disconnectivity of transport of the coarsest bed material even in the case of the 20-year flood event. The longitudinal profile of the channel that

  8. Coronal Fine Structure in Dynamic Events Observed by Hi-C

    NASA Technical Reports Server (NTRS)

    Winebarger, Amy; Schuler, Timothy

    2013-01-01

    The High-Resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket on 2012 July 11 and captured roughly 345 s of high spatial and temporal resolution images of the solar corona in a narrowband 193 Angstrom channel. We have analyzed the fluctuations in intensity of Active Region 11520. We selected events based on a lifetime greater than 11 s (two Hi-C frames) and intensities greater than a threshold determined from the photon and readout noise. We compare the Hi-C events with those determined from AIA. We find that HI-C detects shorter and smaller events than AIA. We also find that the intensity increase in the Hi-C events is approx. 3 times greater than the intensity increase in the AIA events we conclude the events are related to linear sub-structure that is unresolved by AIA

  9. Building a family: unplanned events.

    PubMed

    Bongaarts, J

    1984-01-01

    Couples in developed societies are often unsuccessful in achieving precise family building goals despite the widespread use of birth control. Unplanned events that frustrate reproductive intentions to varying degrees include contraceptive failure, sterility, miscarriage, prolonged conception delay, undesired sex combination of offspring, divorce, and the death of a spouse or a child. This paper reviews the probability of the occurrence of these events using US data. It is concluded that the large majority of newlyweds will experience at least one unplanned event during the family building phase of the life cycle. PMID:6701951

  10. Periodicity in marine extinction events

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. John, Jr.; Raup, David M.

    1986-01-01

    The periodicity of extinction events is examined in detail. In particular, the temporal distribution of specific, identifiable extinction events is analyzed. The nature and limitations of the data base on the global fossil record is discussed in order to establish limits of resolution in statistical analyses. Peaks in extinction intensity which appear to differ significantly from background levels are considered, and new analyses of the temporal distribution of these peaks are presented. Finally, some possible causes of periodicity and of interdependence among extinction events over the last quarter billion years of earth history are examined.

  11. Responding to the Event Deluge

    NASA Technical Reports Server (NTRS)

    Williams, Roy D.; Barthelmy, Scott D.; Denny, Robert B.; Graham, Matthew J.; Swinbank, John

    2012-01-01

    We present the VOEventNet infrastructure for large-scale rapid follow-up of astronomical events, including selection, annotation, machine intelligence, and coordination of observations. The VOEvent.standard is central to this vision, with distributed and replicated services rather than centralized facilities. We also describe some of the event brokers, services, and software that .are connected to the network. These technologies will become more important in the coming years, with new event streams from Gaia, LOF AR, LIGO, LSST, and many others

  12. Channeled and microactiviation of materials

    SciTech Connect

    Maggiore, C.J.; Blacic, J.D.; Blondiaux, G.; Debrun, J.L.; Ali, M.H.; Mathez, E.; Misdaq, M.A.; Valladon, M.

    1988-01-01

    Charged particle activation analysis can be combined with channeling to determine lattice location of impurities at the trace level in single crystal samples. It can also be used with a nuclear microprobe to measure impurities at trace levels in small or spatially inhomogeneous samples. Examples of these extensions of activation analysis to realistic samples are carbon determination in organometallic vapor phase epitaxial layers of GaAlAs on GaAs and oxygen determination in diamonds. 5 refs., 2 figs.

  13. A Latin American Perspective on Ion Channels.

    PubMed

    Elgoyhen, Ana Belén; Barajas-López, Carlos

    2016-09-01

    Ion channels, both ligand- and voltage-gated, play fundamental roles in many physiologic processes. Alteration in ion channel function underlies numerous pathologies, including hypertension, diabetes, chronic pain, epilepsy, certain cancers, and neuromuscular diseases. In addition, an increasing number of inherited and de novo ion channel mutations have been shown to contribute to disease states. Ion channels are thus a major class of pharmacotherapeutic targets. PMID:27535998

  14. Detecting Lower Bounds to Quantum Channel Capacities.

    PubMed

    Macchiavello, Chiara; Sacchi, Massimiliano F

    2016-04-01

    We propose a method to detect lower bounds to quantum capacities of a noisy quantum communication channel by means of a few measurements. The method is easily implementable and does not require any knowledge about the channel. We test its efficiency by studying its performance for most well-known single-qubit noisy channels and for the generalized Pauli channel in an arbitrary finite dimension.

  15. Artificial water channels--incipient innovative developments.

    PubMed

    Barboiu, Mihail

    2016-04-28

    Aquaporins (AQPs) are biological water channels known for fast water transport (∼10(8)-10(9) water molecules per s per channel), with complete proton/ion exclusion. Few synthetic channels have been designed to mimic this high water permeability and to reject ions at a significant level. This Feature Article will discuss the incipient developments of the first artificial water channel systems. PMID:27046217

  16. AVHRR channel selection for land cover classification

    USGS Publications Warehouse

    Maxwell, S.K.; Hoffer, R.M.; Chapman, P.L.

    2002-01-01

    Mapping land cover of large regions often requires processing of satellite images collected from several time periods at many spectral wavelength channels. However, manipulating and processing large amounts of image data increases the complexity and time, and hence the cost, that it takes to produce a land cover map. Very few studies have evaluated the importance of individual Advanced Very High Resolution Radiometer (AVHRR) channels for discriminating cover types, especially the thermal channels (channels 3, 4 and 5). Studies rarely perform a multi-year analysis to determine the impact of inter-annual variability on the classification results. We evaluated 5 years of AVHRR data using combinations of the original AVHRR spectral channels (1-5) to determine which channels are most important for cover type discrimination, yet stabilize inter-annual variability. Particular attention was placed on the channels in the thermal portion of the spectrum. Fourteen cover types over the entire state of Colorado were evaluated using a supervised classification approach on all two-, three-, four- and five-channel combinations for seven AVHRR biweekly composite datasets covering the entire growing season for each of 5 years. Results show that all three of the major portions of the electromagnetic spectrum represented by the AVHRR sensor are required to discriminate cover types effectively and stabilize inter-annual variability. Of the two-channel combinations, channels 1 (red visible) and 2 (near-infrared) had, by far, the highest average overall accuracy (72.2%), yet the inter-annual classification accuracies were highly variable. Including a thermal channel (channel 4) significantly increased the average overall classification accuracy by 5.5% and stabilized inter-annual variability. Each of the thermal channels gave similar classification accuracies; however, because of the problems in consistently interpreting channel 3 data, either channel 4 or 5 was found to be a more

  17. A Latin American Perspective on Ion Channels.

    PubMed

    Elgoyhen, Ana Belén; Barajas-López, Carlos

    2016-09-01

    Ion channels, both ligand- and voltage-gated, play fundamental roles in many physiologic processes. Alteration in ion channel function underlies numerous pathologies, including hypertension, diabetes, chronic pain, epilepsy, certain cancers, and neuromuscular diseases. In addition, an increasing number of inherited and de novo ion channel mutations have been shown to contribute to disease states. Ion channels are thus a major class of pharmacotherapeutic targets.

  18. High spin spectroscopy near the N=Z line: Channel selection and excitation energy systematics

    SciTech Connect

    Svensson, C.E.; Cameron, J.A.; Flibotte, S.

    1996-12-31

    The total {gamma}-ray and charged-particle energies emitted in fusion-evaporation reactions leading to N=Z compound systems in the A = 50-70 mass region have been measured with the 8{pi} {gamma}-ray spectrometer and the miniball charged-particle detector array. A new method of channel selection has been developed which combines particle identification with these total energy measurements and greatly improves upon the selectivity possible with particle detection alone. In addition, the event by event measurement of total {gamma}-ray energies using the BGO ball of the 8{pi} spectrometer has allowed a determination of excitation energies following particle evaporation for a large number of channels in several different reactions. The new channel selection procedure and excitation energy systematics are illustrated with data from the reaction of {sup 24}Mg on {sup 40}Ca at E{sub lab} = 80MeV.

  19. Water channels in peritoneal dialysis.

    PubMed

    Devuyst, Olivier

    2010-01-01

    Peritoneal dialysis involves diffusive and convective transports and osmosis through the highly vascularized peritoneal membrane. Several lines of evidence have demonstrated that the water channel aquaporin-1 (AQP1) corresponds to the ultrasmall pore predicted by the modelization of peritoneal transport. Proof-of-principle studies have shown that up-regulation of the expression of AQP1 in peritoneal capillaries is reflected by increased water permeability and ultrafiltration, without affecting the osmotic gradient and the permeability for small solutes. Inversely, studies in Aqp1 mice have shown that haploinsufficiency in AQP1 is reflected by significant attenuation of water transport. Recent studies have identified lead compounds that could act as agonists of aquaporins, as well as putative binding sites and potential mechanisms of gating the water channel. By modulating water transport, these pharmacological agents could have clinically relevant effects in targeting specific tissues or disease states. These studies on the peritoneal membrane also provide an experimental framework to investigate the role of water channels in the endothelium and various cell types.

  20. Curved channel MCP improvement program

    NASA Technical Reports Server (NTRS)

    Laprade, Bruce N.; Corbett, Michael B.

    1987-01-01

    Blowholes and blemishes were determined to start at two stages of manufacturing. Sperical blowholes resulted from trapped gas between the high melting temperature bond glass and the MCP wafer. During thermal processing, the trapped gas expanded and displaced the softened channel glass to form a spherical inclusion. This defect was eliminated by grinding the prefritted bond wafer and channel plate wafer to a flatness which ensured intimate contact prior to fusion. Elliptical blowholes or blemishes were introduced during the fiber draw stage. Contaminants trapped between the core bar and clad tubing volatized providing large quantities of expanding gas. These pockets of gas became elongated to an ellipsoidal shape during fiber draw. Special cleanliness procedures were developed for the grinding, polishing, and acid etching of core bars. Improvements in channel curvature fabrication were implemented. The design of the shearing fixture was evaluated. A new design was developed which eliminated an off-axis moment. The shearing furnace design was evaluated. Steady state thermal conditions instead of thermal transient conditions were determined to reduce curvature nonuniformity.

  1. Multiple channel data acquisition system

    DOEpatents

    Crawley, H. Bert; Rosenberg, Eli I.; Meyer, W. Thomas; Gorbics, Mark S.; Thomas, William D.; McKay, Roy L.; Homer, Jr., John F.

    1990-05-22

    A multiple channel data acquisition system for the transfer of large amounts of data from a multiplicity of data channels has a plurality of modules which operate in parallel to convert analog signals to digital data and transfer that data to a communications host via a FASTBUS. Each module has a plurality of submodules which include a front end buffer (FEB) connected to input circuitry having an analog to digital converter with cache memory for each of a plurality of channels. The submodules are interfaced with the FASTBUS via a FASTBUS coupler which controls a module bus and a module memory. The system is triggered to effect rapid parallel data samplings which are stored to the cache memories. The cache memories are uploaded to the FEBs during which zero suppression occurs. The data in the FEBs is reformatted and compressed by a local processor during transfer to the module memory. The FASTBUS coupler is used by the communications host to upload the compressed and formatted data from the module memory. The local processor executes programs which are downloaded to the module memory through the FASTBUS coupler.

  2. Multiple channel data acquisition system

    DOEpatents

    Crawley, H.B.; Rosenberg, E.I.; Meyer, W.T.; Gorbics, M.S.; Thomas, W.D.; McKay, R.L.; Homer, J.F. Jr.

    1990-05-22

    A multiple channel data acquisition system for the transfer of large amounts of data from a multiplicity of data channels has a plurality of modules which operate in parallel to convert analog signals to digital data and transfer that data to a communications host via a FASTBUS. Each module has a plurality of submodules which include a front end buffer (FEB) connected to input circuitry having an analog to digital converter with cache memory for each of a plurality of channels. The submodules are interfaced with the FASTBUS via a FASTBUS coupler which controls a module bus and a module memory. The system is triggered to effect rapid parallel data samplings which are stored to the cache memories. The cache memories are uploaded to the FEBs during which zero suppression occurs. The data in the FEBs is reformatted and compressed by a local processor during transfer to the module memory. The FASTBUS coupler is used by the communications host to upload the compressed and formatted data from the module memory. The local processor executes programs which are downloaded to the module memory through the FASTBUS coupler. 25 figs.

  3. Monitoring the lateral channel movements on the alluvial fan of Wadi Feiran drainage basin, South Sinai, Egypt using multi-temporal satellite imagery

    NASA Astrophysics Data System (ADS)

    Hermas, E. A.; Abou El-Magd, I. H.; Saleh, A. S.

    2010-08-01

    Human activities triggered various lateral channel movements over the alluvial fan of Wadi Feiran drainage basin, south Sinai, Egypt. Landsat TM images dated 1986, 1996, and 2001, along with a SPOT 4 XS image dated 2006 were acquired to monitor the lateral channel movement on the alluvial fan of Wadi Feiran through the last two decades. The lateral channel movements have been initiated by the channel avulsion of the incised channel of the alluvial fan as a result of obstructing the flow by developing a man-made barrier from the accumulated flood debris in the early years of 1990(s). The man-made barrier had evolved into an elevated concrete road of 3.75 m height with two culverts underneath directly south the fan apex by March 2007. These human activities enforced the incised channel to avulse in a new location leaving the original path and the active depositional lobe of the fan abandoned. Under the influence of successive flash flood events through the last twenty years, channel aggradations occurred resulting in channel braiding and channel widening processes in the reaches of the new formed distributary channels. The channel widening processes occurred on the expense of the inactive fan lobes located within and south the reaches of the new distributary channels. Observing the southward lateral growth of the reaches of the new formed distributary channels implies the possibility of forming a new active depositional lobe that could be merged with the abandoned depositional lobe of the fan.

  4. The use of "grand master" events for waveform cross correlation

    NASA Astrophysics Data System (ADS)

    Kitov, I. O.; Bobrov, D.; Given, J. W.

    2012-12-01

    higher sensitivity for the cross correlation method relative to beam forming method where the channels are stacked with the theoretical delays. As a result, the waveform cross correlation technique detects more valid signals at local, regional, and global levels. In assessing the performance of the grand master approach the aftershock sequence of the April 11, 2012 Sumatra earthquake (Ms(IDC)=8.2) was used, with16 master events (actual aftershocks) distributed over an area of 500x500 km. Waveform templates from the best master event over a regular grid with 1o spacing have been replicated. There are two principal procedures in comparing the performance of actual and replicated master events as associated with various characteristics/distributions of detections, as well as with the number of event hypotheses built with the varying sets of stations and locations. Both methods have shown the superiority of the replicated events distributed over a regular grid. Such distributions also reduce the volume of calculations by two orders of magnitude. When appropriately chosen, the grand master allows a reduction in the magnitude threshold of seismic monitoring and improving the accuracy and uncertainty of event locations at the IDC to the level of the best located events. When a ground truth event is available, one can expand its influence over hundreds of kilometers.

  5. 47 CFR 95.29 - Channels available.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... no more than 5 watts ERP. (g) Fixed stations in GMRS systems authorized before March 18, 1968... transmission of another GMRS station on a different channel or channels), the licensee of the GMRS system must... GMRS system from the following 462 MHz channels: 462.5500, 462.5750, 462.6000, 462.6250, 462.6500,...

  6. Controls on sinuosity evolution within submarine channels

    NASA Astrophysics Data System (ADS)

    Kane, Ian A.; McCaffrey, William D.; Peakall, Jeff

    2008-04-01

    The planform geometry of submarine channels commonly exhibitsa spatiotemporal stability generally not observed in fluvialchannels. As such, submarine channels tend to lack the meanderloop cutoffs and frequent avulsion history typical of fluvialchannels. Fluvial sinuosity develops through inner-bend depositionand outer-bend erosion. Inner-bend deposits have also been recognizedin submarine channels, from subsurface and seafloor images andfrom ancient channel outcrops, and have been demonstrated withinphysical models. However, outer-bend sediment accumulationsare a feature thought to be unique to submarine channels. Wereport on physical experiments on channelized, subaqueous, particle-driventurbidity currents that demonstrate that channel-fill architecturerelates directly to the degree of flow bypass, in turn largelydetermined by the degree of confinement. In general, weaklybypassing flows deposit at the outer bend, whereas stronglybypassing flows deposit at the inner bend. Therefore flows withinaggradational channel systems whose axes are bypass dominatedmay preferentially deposit at the inner bend, ultimately havingthe effect of increasing channel sinuosity through time; thisis an evolution pattern commonly observed in seismic images.Once developed, the apparent spatio-temporal longevity of sinuositywithin many systems may be explained by the passage of turbiditycurrents of varying magnitude (and consequently bypass potential)depositing preferentially at either the inner or outer bankof the channel, maintaining a quasistable morphological equilibrium.Fluvial channels do not have the ability to reduce or maintaintheir sinuosity in this way, which plausibly explains why theytend to develop cutoffs at higher rates than subaqueous channels.

  7. Micro Channel/Multibus-II Interface Circuit

    NASA Technical Reports Server (NTRS)

    D'Ambrose, John J.; Jaworski, Richard C.; Heise, Nyles N.; Thornton, David N.

    1991-01-01

    Micro Channel/Multibus-II interface circuit provides electrical interconnections enabling communications between Micro Channels of IBM Personal System/2 computers and IEEE 1296 standard Multibus-II parallel system bus (iPSB). Made mostly of commercially available parts, interface enables independent Micro Channels to communicate over iPSB without modification.

  8. Communication Channels and Information Flow among Ethnics.

    ERIC Educational Resources Information Center

    Jeffres, Leo W.; Hur, K. Kyoon

    The questionnaire responses of 768 people from a variety of ethnic groups were analyzed to determine what communication channels were used to link ethnics to their native countries and to provide news of the ethnic community. The relationships between channel preferences and demographics, ethnicity, and communication channel patterns were also…

  9. Language Planning, Channel Management, and ESP.

    ERIC Educational Resources Information Center

    Kennedy, Chris

    Channel management, a concept developed in marketing to refer to the process by which a product is moved from production to consumption, uses a channel of distribution operating at several levels, each responsible for one or more of the activities of moving the product forward to the consumer. The function of channel management is to select the…

  10. Channel One: But What about the Advertising?

    ERIC Educational Resources Information Center

    Greenberg, Bradley S.; Brand, Jeffrey E.

    1994-01-01

    A survey of students in Channel One and control schools showed that regular viewing of Channel One reinforces materialistic attitudes. Youngsters are bombarded daily with advertising from adolescent-oriented radio stations, magazines, and TV programs outside school. Channel One does provide educators with a excellent opportunity to educate youth…

  11. Cleaning of contaminated channel electron multiplier arrays.

    NASA Technical Reports Server (NTRS)

    Harlow, F. E.; Hunter, W. R.

    1972-01-01

    Polymerized organic materials found in vacuum systems frequently contaminate the individual channels (which can be as small as 15 microns) of an oil-pumped channel electron multiplier array used as a vacuum UV- to visible-radiation conversion device. It is shown that exposure to an oxygen plasma is an effective means of decontaminating the channels, thereby restoring the sensitivity of the device.

  12. Requirement for the synaptic protein interaction site for reconstitution of synaptic transmission by P/Q-type calcium channels

    PubMed Central

    Mochida, Sumiko; Westenbroek, Ruth E.; Yokoyama, Charles T.; Zhong, Huijun; Myers, Scott J.; Scheuer, Todd; Itoh, Kanako; Catterall, William A.

    2003-01-01

    Cav2.1 channels, which conduct P/Q-type Ca2+ currents, were expressed in superior cervical ganglion neurons in cell culture, and neurotransmission initiated by these exogenously expressed Ca2+ channels was measured. Deletions in the synaptic protein interaction (synprint) site in the intracellular loop between domains II and III of Cav2.1 channels reduced their effectiveness in synaptic transmission. Surprisingly, this effect was correlated with loss of presynaptic localization of the exogenously expressed channels. Cav1.2 channels, which conduct L-type Ca2+ currents, are ineffective in supporting synaptic transmission, but substitution of the synprint site from Cav2.1 channels in Cav1.2 was sufficient to establish synaptic transmission initiated by L-type Ca2+ currents through the exogenous Cav1.2 channels. Substitution of the synprint site from Cav2.2 channels, which conduct N-type Ca2+ currents, was even more effective than Cav2.1. Our results show that localization and function of exogenous Ca2+ channels in nerve terminals of superior cervical ganglion neurons require a functional synprint site and suggest that binding of soluble NSF attachment protein receptor (SNARE) proteins to the synprint site is a necessary permissive event for nerve terminal localization of presynaptic Ca2+ channels. PMID:12601156

  13. Molecular dynamics of ion transport through the open conformation of a bacterial voltage-gated sodium channel.

    PubMed

    Ulmschneider, Martin B; Bagnéris, Claire; McCusker, Emily C; Decaen, Paul G; Delling, Markus; Clapham, David E; Ulmschneider, Jakob P; Wallace, B A

    2013-04-16

    The crystal structure of the open conformation of a bacterial voltage-gated sodium channel pore from Magnetococcus sp. (NaVMs) has provided the basis for a molecular dynamics study defining the channel's full ion translocation pathway and conductance process, selectivity, electrophysiological characteristics, and ion-binding sites. Microsecond molecular dynamics simulations permitted a complete time-course characterization of the protein in a membrane system, capturing the plethora of conductance events and revealing a complex mixture of single and multi-ion phenomena with decoupled rapid bidirectional water transport. The simulations suggest specific localization sites for the sodium ions, which correspond with experimentally determined electron density found in the selectivity filter of the crystal structure. These studies have also allowed us to identify the ion conductance mechanism and its relation to water movement for the NavMs channel pore and to make realistic predictions of its conductance properties. The calculated single-channel conductance and selectivity ratio correspond closely with the electrophysiology measurements of the NavMs channel expressed in HEK 293 cells. The ion translocation process seen in this voltage-gated sodium channel is clearly different from that exhibited by members of the closely related family of voltage-gated potassium channels and also differs considerably from existing proposals for the conductance process in sodium channels. These studies simulate sodium channel conductance based on an experimentally determined structure of a sodium channel pore that has a completely open transmembrane pathway and activation gate.

  14. The Role of Conjoining (Tie) Channels in Lowland Floodplain Development and Lake Infilling

    NASA Astrophysics Data System (ADS)

    Rowland, J. C.; Dietrich, W. E.; Day, G.; Lepper, K.; Wilson, C. J.

    2003-12-01

    In simple models of lowland river systems, water and sediment enter the main stem via tributary and secondary channels and are only redistributed to the floodplain during overbank and crevasse splay events. Along numerous river systems across the globe, however, water and sediment are regularly exchanged between the river and off river water bodies via stable, narrow channels. These channels, known as tie channels on the Fly River in Papua New Guinea and batture channels along the lower Mississippi, are largely overlooked but important components of floodplain sediment dispersal where they exist. These channels become pathways of sediment dispersal to the floodplain system when elevated river stages force sediment-laden flows into the off-river water bodies. On the Fly River, it is estimated that about 50% of the sediment delivery to the floodplain is via these channels, and along low gradient tributary channels during flood driven flow reversals. During low flow, tie channels serve to drain the floodplain. With the outgoing flows, large amounts sediment can be carried and lost to the floodplain; floodplain lakes progressively infill with sediment as the mouth of these channels steadily prograde lakeward. These lake deposits not only become significant stratigraphic components of floodplains (traditionally referred to as clay plugs), but are important local sinks recording hundreds to thousands of years of river history. As with all sinks, the proper interpretation of these stratigraphic records requires understanding the processes by which sediment is delivered to the sink and how these processes alter the paleohydraulic and climatic signals of interest. We have conducted field investigations of conjoining channels in Papua New Guinea (the Fly and Strickland Rivers), Louisiana (Raccourci Old River ~ 65 km upriver of Baton Rouge) and Alaska (Birch Creek). These field investigations include extensive surveys of both cross and along channel morphological trends

  15. Bayesian Mulitple-Event Location

    2010-03-30

    Bayesloc is a statistical model of the multiple seismic location system, including event hypocenters, corrections to model-based travel time predictions, assessments precision for measurement phase arrival times, and phase lavels which indicate phase ray path.

  16. Life Events, Stress, and Illness

    ERIC Educational Resources Information Center

    Rabkin, Judith G.; Struening, Elmer L.

    1976-01-01

    Selectively reviews the research literature on the relation of life events, stress, and the onset of illness; delineates trends in the development of this research, and evaluates the conceptual and methodological approaches employed. (MLH)

  17. MGR External Events Hazards Analysis

    SciTech Connect

    L. Booth

    1999-11-06

    The purpose and objective of this analysis is to apply an external events Hazards Analysis (HA) to the License Application Design Selection Enhanced Design Alternative 11 [(LADS EDA II design (Reference 8.32))]. The output of the HA is called a Hazards List (HL). This analysis supersedes the external hazards portion of Rev. 00 of the PHA (Reference 8.1). The PHA for internal events will also be updated to the LADS EDA II design but under a separate analysis. Like the PHA methodology, the HA methodology provides a systematic method to identify potential hazards during the 100-year Monitored Geologic Repository (MGR) operating period updated to reflect the EDA II design. The resulting events on the HL are candidates that may have potential radiological consequences as determined during Design Basis Events (DBEs) analyses. Therefore, the HL that results from this analysis will undergo further screening and analysis based on the criteria that apply during the performance of DBE analyses.

  18. Measurement of the Top Quark Mass Simultaneously in Dilepton and Lepton + Jets Decay Channels

    SciTech Connect

    Fedorko, Wojciech T.

    2008-12-01

    The authors present the first measurement of the top quark mass using simultaneously data from two decay channels. They use a data sample of √s = 1.96 TeV collisions with integrated luminosity of 1.9 fb-1 collected by the CDF II detector. They select dilepton and lepton + jets channel decays of t$\\bar{t}$ pairs and reconstruct two observables in each topology. They use non-parametric techniques to derive probability density functions from simulated signal and background samples. The observables are the reconstructed top quark mass and the scalar sum of transverse energy of the event in the dilepton topology and the reconstructed top quark mass and the invariant mass of jets from the W boson decay in lepton + jets channel. They perform a simultaneous fit for the top quark mass and the jet energy scale which is constrained in situ by the hadronic W boson resonance from the lepton + jets channel. Using 144 dilepton candidate events and 332 lepton + jets candidate events they measure: Mtop = 171.9 ± 1.7 (stat. + JES) ± 1.1 (other sys.) GeV/c2 = 171.9 ± 2.0 GeV/c2. The measurement features a robust treatment of the systematic uncertainties, correlated between the two channels and develops techniques for a future top quark mass measurement simultaneously in all decay channels. Measurements of the W boson mass and the top quark mass provide a constraint on the mass of the yet unobserved Higgs boson. The Higgs boson mass implied by measurement presented here is higher than Higgs boson mass implied by previously published, most precise CDF measurements of the top quark mass in lepton + jets and dilepton channels separately.

  19. Concurrency and discrete event control

    NASA Technical Reports Server (NTRS)

    Heymann, Michael

    1990-01-01

    Much of discrete event control theory has been developed within the framework of automata and formal languages. An alternative approach inspired by the theories of process-algebra as developed in the computer science literature is presented. The framework, which rests on a new formalism of concurrency, can adequately handle nondeterminism and can be used for analysis of a wide range of discrete event phenomena.

  20. Pluto-charon mutual events

    SciTech Connect

    Binzel, R.P. )

    1989-11-01

    Since 1985, planetary astronomers have been working to take advantage of a once-per-century apparent alignment between Pluto and its satellite, Charon, which has allowed mutual occultation and transit events to be observed. There events, which will cease in 1990, have permitted the first precise determinations of their individual radii, densities, and surface compositions. In addition, information on their surface albedo distributions can be obtained.

  1. Joint source-channel coding with allpass filtering source shaping for image transmission over noisy channels

    NASA Astrophysics Data System (ADS)

    Cai, Jianfei; Chen, Chang W.

    2000-04-01

    In this paper, we proposed a fixed-length robust joint source- channel coding (JSCC) scheme for image transmission over noisy channels. Three channel models are studied: binary symmetric channels (BSC) and additive white Gaussian noise (AWGN) channels for memoryless channels, and Gilbert-Elliott channels (GEC) for bursty channels. We derive, in this research, an explicit operational rate-distortion (R-D) function, which represents an end-to-end error measurement that includes errors due to both quantization and channel noise. In particular, we are able to incorporate the channel transition probability and channel bit error rate into the R-D function in the case of bursty channels. With the operational R-D function, bits are allocated not only among different subsources, but also between source coding and channel coding so that, under a fixed transmission rate, an optimum tradeoff between source coding accuracy and channel error protection can be achieved. This JSCC scheme is also integrated with allpass filtering source shaping to further improve the robustness against channel errors. Experimental results show that the proposed scheme can achieve not only high PSNR performance, but also excellent perceptual quality. Compared with the state-of-the-art JSCC schemes, this proposed scheme outperforms most of them especially when the channel mismatch occurs.

  2. 77 FR 41914 - Safety Zones; Annual Fireworks Events in the Captain of the Port Buffalo Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-17

    ... email Waterways Management Division, Coast Guard Sector Buffalo, 1 Fuhrmann Blvd., Buffalo, NY 14203... Buffalo Zone listed in 33 CFR 165.939 for the following events: (1) Fairport Harbor Mardi Gras, Fairport... Captain of the Port Buffalo via channel 16, VHF-FM. Vessels and persons granted permission to enter one...

  3. Na+ Channel β Subunits: Overachievers of the Ion Channel Family

    PubMed Central

    Brackenbury, William J.; Isom, Lori L.

    2011-01-01

    Voltage-gated Na+ channels (VGSCs) in mammals contain a pore-forming α subunit and one or more β subunits. There are five mammalian β subunits in total: β1, β1B, β2, β3, and β4, encoded by four genes: SCN1B–SCN4B. With the exception of the SCN1B splice variant, β1B, the β subunits are type I topology transmembrane proteins. In contrast, β1B lacks a transmembrane domain and is a secreted protein. A growing body of work shows that VGSC β subunits are multifunctional. While they do not form the ion channel pore, β subunits alter gating, voltage-dependence, and kinetics of VGSCα subunits and thus regulate cellular excitability in vivo. In addition to their roles in channel modulation, β subunits are members of the immunoglobulin superfamily of cell adhesion molecules and regulate cell adhesion and migration. β subunits are also substrates for sequential proteolytic cleavage by secretases. An example of the multifunctional nature of β subunits is β1, encoded by SCN1B, that plays a critical role in neuronal migration and pathfinding during brain development, and whose function is dependent on Na+ current and γ-secretase activity. Functional deletion of SCN1B results in Dravet Syndrome, a severe and intractable pediatric epileptic encephalopathy. β subunits are emerging as key players in a wide variety of physiopathologies, including epilepsy, cardiac arrhythmia, multiple sclerosis, Huntington’s disease, neuropsychiatric disorders, neuropathic and inflammatory pain, and cancer. β subunits mediate multiple signaling pathways on different timescales, regulating electrical excitability, adhesion, migration, pathfinding, and transcription. Importantly, some β subunit functions may operate independently of α subunits. Thus, β subunits perform critical roles during development and disease. As such, they may prove useful in disease diagnosis and therapy. PMID:22007171

  4. Superstatistics and renewal critical events

    NASA Astrophysics Data System (ADS)

    Paradisi, Paolo; Cesari, Rita; Grigolini, Paolo

    2009-09-01

    An approach to intermittent systems based on renewal processes is reviewed. The Waiting Times (WTs) between events are the main variables of interest in intermittent systems. A crucial role is played by the class of critical events, characterized by Non-Poisson statistics and non-exponential WT distribution. A particular important case is given by WT distributions with power tail. Critical events play a crucial role in the behavior of a property known as Renewal Aging. Focusing on the role of critical events, the relation between superstatistics and non-homogeneous Poisson processes is discussed, and the role of Renewal Aging is illustrated by comparing a Non-Poisson model with a Poisson one, both of them modulated by a periodic forcing. It is shown that the analysis of Renewal Aging is sensitive to the presence of critical events and that this property can be exploited to detect Non-Poisson statistics in a time series. As a consequence, it is claimed that, apart from the characterization of superstatistical features such as the distribution of the intensive parameter or the separation of the time scales, the Renewal Aging property can give some effort to better determine the role of Non-Poisson critical events in intermittent systems.

  5. Analysis of water channels by molecular dynamics simulation of heterotetrameric sarcosine oxidase

    PubMed Central

    Watanabe, Go; Nakajima, Daisuke; Hiroshima, Akinori; Suzuki, Haruo; Yoneda, Shigetaka

    2015-01-01

    A precise 100-ns molecular dynamics simulation in aquo was performed for the heterotetrameric sarcosine oxidase bound with a substrate analogue, dimethylglycine. The spatial region including the protein was divided into small rectangular cells. The average number of the water molecules locating within each cell was calculated based on the simulation trajectory. The clusters of the cells filled with water molecules were used to determine the water channels. The narrowness of the channels, the average hydropathy indices of the residues of the channels, and the number of migration events of water molecules through the channels were consistent with the selective transport hypothesis whereby tunnel T3 is the pathway for the exit of the iminium intermediate of the enzyme reaction. PMID:27493862

  6. The mucolipidosis IV Ca2+ channel TRPML1 (MCOLN1) is regulated by the TOR kinase.

    PubMed

    Onyenwoke, Rob U; Sexton, Jonathan Z; Yan, Feng; Díaz, María Cristina Huertas; Forsberg, Lawrence J; Major, Michael B; Brenman, Jay E

    2015-09-15

    Autophagy is a complex pathway regulated by numerous signalling events that recycles macromolecules and may be perturbed in lysosomal storage disorders (LSDs). During autophagy, aberrant regulation of the lysosomal Ca(2+) efflux channel TRPML1 [transient receptor potential mucolipin 1 (MCOLN1)], also known as MCOLN1, is solely responsible for the human LSD mucolipidosis type IV (MLIV); however, the exact mechanisms involved in the development of the pathology of this LSD are unknown. In the present study, we provide evidence that the target of rapamycin (TOR), a nutrient-sensitive protein kinase that negatively regulates autophagy, directly targets and inactivates the TRPML1 channel and thereby functional autophagy, through phosphorylation. Further, mutating these phosphorylation sites to unphosphorylatable residues proved to block TOR regulation of the TRPML1 channel. These findings suggest a mechanism for how TOR activity may regulate the TRPML1 channel.

  7. 75 FR 67214 - Special Local Regulations for Marine Events; Wrightsville Channel, Wrightsville Beach, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-02

    ... Beach, NC in the Federal Register (75 FR 56024). We received no comments on the proposed rule. No public... Battleship Full and Half Iron Distance Triathlon,'' to be held on the waters adjacent to Wrightsville Beach... 13, 2010, the Wilmington YMCA will sponsor the ``Beach 2 Battleship Full and Half Iron...

  8. 76 FR 60729 - Special Local Regulations for Marine Events, Wrightsville Channel; Wrightsville Beach, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... Battleship Full and Half Iron Distance Triathlon'', to be held on the waters adjacent to Wrightsville Beach... participate in the Wilmington YMCA ``Beach 2 Battleship Full and Half Iron Distance Triathlon'', scheduled for... Full and Half Iron Distance Triathlon'' on the waters of Banks, Motts and Wrightsville...

  9. 77 FR 42464 - Special Local Regulations for Marine Events; Potomac River, National Harbor Access Channel, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-19

    ... FR 20750, is withdrawn as of July 19, 2012. ADDRESSES: The docket for this withdrawn rulemaking is... Federal Register (77 FR 20750). The rulemaking ] concerned the Coast Guard's proposal to establish... parades regulations. The rulemaking was initiated to establish special local regulations during the...

  10. 77 FR 20750 - Special Local Regulations for Marine Events; Potomac River, National Harbor Access Channel, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    ..., 2008, issue of the Federal Register (73 FR 3316). Public Meeting We do not now plan to hold a public... rulemaking. SUMMARY: The Coast Guard proposes to establish special local regulations during the swim segment... swim segment of the triathlon will occur on the Potomac River and in portions of the National...

  11. 77 FR 25106 - Special Local Regulations for Marine Events; Potomac River, National Harbor Access Channel, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-27

    ... notice regarding our public dockets in the January 17, 2008, issue of the Federal Register (73 FR 3316... rulemaking. SUMMARY: The Coast Guard proposes to establish special local regulations during the ``Swim Across the Potomac River'' swimming competition, to be held on the waters of the Potomac River on July...

  12. 77 FR 47520 - Special Local Regulations for Marine Events, Wrightsville Channel; Wrightsville Beach, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-09

    ... Security FR Federal Register NPRM Notice of Proposed Rulemaking A. Regulatory History and Information On June 13, 2012 a Notice of Proposed Rule Making (NPRM) was published in 77 FR 35321. We received no...: The Coast Guard is establishing a Special Local Regulation for the ``Swim Harbor Island'' swim...

  13. Alcohol intoxication: Ion channels and genetics

    SciTech Connect

    Harris, A.R.; Allan, A.M. )

    1989-04-01

    Acute in vitro exposure to ethanol and other intoxicant-anesthetics activates {gamma}-aminobutyric acid (GABA)-stimulated chloride channels and inhibits voltage-dependent calcium and sodium channels of isolated brain membranes. The question of whether these neurochemical actions are responsible for intoxication in vivo has been addressed using animal populations displaying genetic differences in sensitivity to alcohol and benzodiazepine intoxication. These genetic approaches include inbred strains, selected lines, recombinant inbred strains, and heterogeneous stocks. Genetic differences in ion channel function provide strong evidence for a role of the GABA-stimulated chloride channel in ethanol and benzodiazepine intoxication; the role of calcium and sodium channels is less clear.

  14. CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.

    USGS Publications Warehouse

    Simon, Andrew; Hupp, Cliff R.

    1987-01-01

    This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of channel evolution in disturbed channels was developed by quantifying bed level trends and recognizing qualitative stages of bank slope development. Development of the bank profile is defined in terms of three dynamic and observable surfaces: (a) vertical face (70 to 90 degrees), (b) upper bank (25 to 50 degrees), and (c) slough line (20 to 25 degrees).

  15. High throughput screening technologies for ion channels

    PubMed Central

    Yu, Hai-bo; Li, Min; Wang, Wei-ping; Wang, Xiao-liang

    2016-01-01

    Ion channels are involved in a variety of fundamental physiological processes, and their malfunction causes numerous human diseases. Therefore, ion channels represent a class of attractive drug targets and a class of important off-targets for in vitro pharmacological profiling. In the past decades, the rapid progress in developing functional assays and instrumentation has enabled high throughput screening (HTS) campaigns on an expanding list of channel types. Chronologically, HTS methods for ion channels include the ligand binding assay, flux-based assay, fluorescence-based assay, and automated electrophysiological assay. In this review we summarize the current HTS technologies for different ion channel classes and their applications. PMID:26657056

  16. Braided submarine channels produced with experiments suggest scale independent controls on planform morphology similar to rivers

    NASA Astrophysics Data System (ADS)

    Foreman, B.; Lai, S. Y. J.; Komatsu, Y.; Paola, C.

    2015-12-01

    There are two dominant planform morphologies in channelized aggradational sedimentary systems; meandering and braided. Within marine settings meandering channels formed from turbidity and density currents are the most abundant. Braided channels are rare, and it is unclear if the few documented cases are generated by spontaneous bar deposition or are an artifact of erosive events or seafloor bathymetry. This is in contrast to fluvial systems wherein both meandering and braided planforms are common, and led us to the question if submarine channels require different conditions from river systems to obtain braided planform morphologies. We ran two experimental series wherein we provided density currents with an initial channel geometry known to produce braiding in natural and experimental river systems. Fluvial braiding occurs across a wide range of scales, and we predicted the same would hold true for subaqueous systems. The two experiments had initial width to depth ratios of 1000:1 and 350:1 and similar sediment to saline water discharge ratios of 0.02 and 0.03, and a saline current with a density contrast similar to natural currents. The experiments freely evolved a network of individual channels separated by depositional bars. Moreover, existing stability model theory for fluvial systems successfully explains both braided and meandering submarine channels from a compilation of lab and field examples. This suggests the aspect ratio of the flow determines the planform morphology, and that it is a scale independent phenomenon. The rarity of braided submarine channels in nature is more likely explained by factors that inhibit channel widening in submarine systems as compared to fluvial systems. We suggest the cause is a combination of the relatively thicker flow depths of turbidity currents that require commensurately wider flows, and a variety of feedbacks that tend to yield higher overbank sedimentation rates in submarine channels compared to fluvial systems.

  17. Evolution of gravel-bed channels in response to flash floods in dry environments

    NASA Astrophysics Data System (ADS)

    Salomon, Reut; Morin, Efrat; Enzel, Yehouda; Haviv, Itai

    2016-04-01

    Longitudinal profiles of alluvial channels may be altered rapidly in response to base-level lowering or changes in streamflow regime. Previous models simulating the response to such changes assumed steady and uniform streamflow discharge, or used a calibrated diffusion coefficient as a proxy for stream discharge. Such models do not account for intra and inter annual variance of flash flood volume and peak discharge which is typically high in channels of dry environments. We developed a new model for evolution of longitudinal profiles of gravel-bed channels combining kinematic wave flood routing with sediment transport based on the Meyer-Peter-Muller equation. The model predicts changes in channel longitudinal profile in response to changing streamflow regimes and base-level lowering rates. We have adopted a stochastic approach by formulating a "flash flood generator" which produces a synthetic data series of floods based on the probability distribution of peak discharge and hydrograph properties in a specific basin. The model was applied to the lower reach of Nahal Darga gravel-bed channel which drains into the Dead Sea Lake and is located in a dry climate regime. During the last 40 years, the initial uniform-gradient profile of this reach has changed to a convex profile as a result of a drastic artificial lowering of the Dead Sea level at a rate of 1 m/y. Measured channel profiles at several points in time were used for the model evaluation. The effect of different scenarios of lake level drop and of flash flood regime on the channel profile has been examined. The modeling results indicate a wide range of possible channel profiles due to the natural flow variance under a given flow regime. Extreme flow events play a major role on the channel profile evolution. Nevertheless, the effective discharge at the Darga channel, consists of floods with medium peak discharge and a recurrence interval of ~10 years.

  18. Riparian vegetation controls on channels formed in non-cohesive sediment

    NASA Astrophysics Data System (ADS)

    Gran, K.; Tal, M.; Paola, C.

    2002-05-01

    , vegetation is reseeded following repeat high flow events, simulating the natural process of vegetation encroachment on the floodplain and channel.

  19. Plasma membrane calcium channels in cancer: Alterations and consequences for cell proliferation and migration.

    PubMed

    Déliot, Nadine; Constantin, Bruno

    2015-10-01

    The study of calcium channels in molecular mechanisms of cancer transformation is still a novel area of research. Several studies, mostly conducted on cancer cell lines, however support the idea that a diversity of plasma membrane channels participates in the remodeling of Ca2+ homeostasis, which regulates various cancer hallmarks such as uncontrolled multiplication and increase in migration and invasion abilities. However few is still understood concerning the intracellular signaling cascades mobilized by calcium influx participating to cancer cell behavior. This review intends to gather some of these pathways dependent on plasma membrane calcium channels and described in prostate, breast and lung cancer cell lines. In these cancer cell types, the calcium channels involved in calcium signaling pathways promoting cancer behaviors are mostly non-voltage activated calcium channels and belong to the TRP superfamily (TRPC, TPRPV and TRPM families) and the Orai family. TRP and Orai channels are part of many signaling cascades involving the activation of transmembrane receptors by extracellular ligand from the tumor environment. TRPV can sense changes in the physical and chemical environment of cancer cells and TRPM7 are stretch activated and sensitive to cholesterol. Changes in activation and or expression of plasma-membrane calcium channels affect calcium-dependent signaling processes relevant to tumorigenesis. The studies cited in this review suggest that an increase in plasma membrane calcium channel expression and/or activity sustain an elevated calcium entry (constitutive or under the control of extracellular signals) promoting higher cell proliferation and migration in most cases. A variety of non-voltage-operated calcium channels display change expression and/or activity in a same cancer type and cooperate to the same process relevant to cancer cell behavior, or can be involved in a different sequence of events during the tumorigenesis. This article is part of a

  20. Comparative Morphology of Solar Relativistic Particle Events

    NASA Astrophysics Data System (ADS)

    Kocharov, Leon; Klassen, Andreas; Valtonen, Eino; Usoskin, Ilya; Ryan, James M.

    2015-09-01

    Time profiles of the 0.25–10 MeV electrons and the ∼(0.1–1) GeV nucleon‑1 protons and helium associated with two solar coronal mass ejections (CMEs) are analyzed with a newly formulated method based on modeling of the particle transport in the interplanetary medium. With the modeling, we fit the observed angular distribution of solar particles and infer, for a particular particle instrument and magnetic field orientation, the time delay of the particle registration at 1 AU in respect to the solar source. Then, after the time offset removal, intensity re-normalization and background equalization, the time–intensity profiles of high-energy protons, helium and electrons in different energy channels are superposed and compared. The comparison reveals episodes of remarkable coincidence of different profiles, as well as episodes of essentially different behavior. It implies at least three sources of solar high-energy particles operating in a single event. The first, short-duration source emits electrons next to the flare's impulsive phase and CME liftoff. The second source gradually rises and continues for more than an hour, emitting electrons and lower energy protons, which is consistent with shock acceleration on open magnetic field lines extending to solar wind. An another, third source is the main source of relativistic ions in space. It is retarded in respect to the flare's impulsive phase and may be associated with a structure encountered by the shock within a few solar radii from the Sun.