WorldWideScience

Sample records for identify individual channels

  1. Seismic stochastic inversion identify river channel sand body

    Science.gov (United States)

    He, Z.

    2015-12-01

    The technology of seismic inversion is regarded as one of the most important part of geophysics. By using the technology of seismic inversion and the theory of stochastic simulation, the concept of seismic stochastic inversion is proposed.Seismic stochastic inversion can play an significant role in the identifying river channel sand body. Accurate sand body description is a crucial parameter to measure oilfield development and oilfield stimulation during the middle and later periods. Besides, rational well spacing density is an essential condition for efficient production. Based on the geological knowledge of a certain oilfield, in line with the use of seismic stochastic inversion, the river channel sand body in the work area is identified. In this paper, firstly, the single river channel body from the composite river channel body is subdivided. Secondly, the distribution of river channel body is ascertained in order to ascertain the direction of rivers. Morever, the superimposed relationship among the sand body is analyzed, especially among the inter-well sand body. The last but not at the least, via the analysis of inversion results of first vacuating the wells and continuous infilling later, it is meeted the most needs well spacing density that can obtain the optimal inversion result. It would serve effective guidance for oilfield stimulation.

  2. Comparisons between detection threshold and loudness perception for individual cochlear implant channels

    Science.gov (United States)

    Bierer, Julie Arenberg; Nye, Amberly D

    2014-01-01

    Objective The objective of the present study, performed in cochlear implant listeners, was to examine how the level of current required to detect single-channel electrical pulse trains relates to loudness perception on the same channel. The working hypothesis was that channels with relatively high thresholds, when measured with a focused current pattern, interface poorly to the auditory nerve. For such channels a smaller dynamic range between perceptual threshold and the most comfortable loudness would result, in part, from a greater sensitivity to changes in electrical field spread compared to low-threshold channels. The narrower range of comfortable listening levels may have important implications for speech perception. Design Data were collected from eight, adult cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp.). The partial tripolar (pTP) electrode configuration, consisting of one intracochlear active electrode, two flanking electrodes carrying a fraction (σ) of the return current, and an extracochlear ground, was used for stimulation. Single-channel detection thresholds and most comfortable listening levels were acquired using the most focused pTP configuration possible (σ ≥ 0.8) to identify three channels for further testing – those with the highest, median, and lowest thresholds – for each subject. Threshold, equal-loudness contours (at 50% of the monopolar dynamic range), and loudness growth functions were measured for each of these three test channels using various partial tripolar fractions. Results For all test channels, thresholds increased as the electrode configuration became more focused. The rate of increase with the focusing parameter σ was greatest for the high-threshold channel compared to the median- and low-threshold channels. The 50% equal-loudness contours exhibited similar rates of increase in level across test channels and subjects. Additionally, test channels with the highest

  3. Power Adaptive Feedback Communication over an Additive Individual Noise Sequence Channel

    OpenAIRE

    Lomnitz, Yuval; Feder, Meir

    2009-01-01

    We consider a real-valued additive channel with an individual unknown noise sequence. We present a simple sequential communication scheme based on the celebrated Schalkwijk-Kailath scheme, which varies the transmit power according to the power of the sequence, so that asymptotically the relation between the SNR and the rate matches the Gaussian channel capacity 1/2 log(1+SNR)for almost every noise sequence.

  4. Identifying cochlear implant channels with poor electrode-neuron interface: partial tripolar, single-channel thresholds and psychophysical tuning curves.

    Science.gov (United States)

    Bierer, Julie Arenberg; Faulkner, Kathleen F

    2010-04-01

    The goal of this study was to evaluate the ability of a threshold measure, made with a restricted electrode configuration, to identify channels exhibiting relatively poor spatial selectivity. With a restricted electrode configuration, channel-to-channel variability in threshold may reflect variations in the interface between the electrodes and auditory neurons (i.e., nerve survival, electrode placement, and tissue impedance). These variations in the electrode-neuron interface should also be reflected in psychophysical tuning curve (PTC) measurements. Specifically, it is hypothesized that high single-channel thresholds obtained with the spatially focused partial tripolar (pTP) electrode configuration are predictive of wide or tip-shifted PTCs. Data were collected from five cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp., Sylmar, CA). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the pTP configuration for which a fraction of current (sigma) from a center-active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. Forward-masked PTCs were obtained for channels with the highest, lowest, and median tripolar (sigma = 1 or 0.9) thresholds. The probe channel and level were fixed and presented with either the monopolar (sigma = 0) or a more focused pTP (sigma > or = 0.55) configuration. The masker channel and level were varied, whereas the configuration was fixed to sigma = 0.5. A standard, three-interval, two-alternative forced choice procedure was used for thresholds and masked levels. Single-channel threshold and variability in threshold across channels systematically increased as the compensating current, sigma, increased and the presumed electrical field became more focused. Across subjects, channels with the highest single-channel thresholds, when measured with a

  5. An EEGLAB plugin to analyze individual EEG alpha rhythms using the "channel reactivity-based method".

    Science.gov (United States)

    Goljahani, A; Bisiacchi, P; Sparacino, G

    2014-03-01

    A recent paper [1] proposed a new technique, termed the channel reactivity-based method (CRB), for characterizing EEG alpha rhythms using individual (IAFs) and channel (CAFs) alpha frequencies. These frequencies were obtained by identifying the frequencies at which the power of the alpha rhythms decreases. In the present study, we present a graphical interactive toolbox that can be plugged into the popular open source environment EEGLAB, making it easy to use CRB. In particular, we illustrate the major functionalities of the software and discuss the advantages of this toolbox for common EEG investigations. The CRB analysis plugin, along with extended documentation and the sample dataset utilized in this study, is freely available on the web at http://bio.dei.unipd.it/crb/. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  6. Space-Time Coded MC-CDMA: Blind Channel Estimation, Identifiability, and Receiver Design

    Directory of Open Access Journals (Sweden)

    Li Hongbin

    2002-01-01

    Full Text Available Integrating the strengths of multicarrier (MC modulation and code division multiple access (CDMA, MC-CDMA systems are of great interest for future broadband transmissions. This paper considers the problem of channel identification and signal combining/detection schemes for MC-CDMA systems equipped with multiple transmit antennas and space-time (ST coding. In particular, a subspace based blind channel identification algorithm is presented. Identifiability conditions are examined and specified which guarantee unique and perfect (up to a scalar channel estimation when knowledge of the noise subspace is available. Several popular single-user based signal combining schemes, namely the maximum ratio combining (MRC and the equal gain combining (EGC, which are often utilized in conventional single-transmit-antenna based MC-CDMA systems, are extended to the current ST-coded MC-CDMA (STC-MC-CDMA system to perform joint combining and decoding. In addition, a linear multiuser minimum mean-squared error (MMSE detection scheme is also presented, which is shown to outperform the MRC and EGC at some increased computational complexity. Numerical examples are presented to evaluate and compare the proposed channel identification and signal detection/combining techniques.

  7. Visualizing individual sodium channels on the move.

    Science.gov (United States)

    Heinemann, Stefan H

    2012-07-27

    Visualization of voltage-gated sodium channels at work is an important requirement for the understanding of rapid electrical signaling in nerve cells. In this issue of Chemistry & Biology, Ondrus and colleagues have mastered this challenge by chemical synthesis of a fluorescent antagonist and by monitoring single sodium channels in living cells with unprecedented optical resolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Identifying individual fires from satellite-derived burned area data

    CSIR Research Space (South Africa)

    Archibald, S

    2009-07-01

    Full Text Available An algorithm for identifying individual fires from the Modis burned area data product is introduced for southern Africa. This algorithm gives the date of burning, size of fire, and location of the centroid for all fires identified over 8 years...

  9. Use of color-coded sleeve shutters accelerates oscillograph channel selection

    Science.gov (United States)

    Bouchlas, T.; Bowden, F. W.

    1967-01-01

    Sleeve-type shutters mechanically adjust individual galvanometer light beams onto or away from selected channels on oscillograph papers. In complex test setups, the sleeve-type shutters are color coded to separately identify each oscillograph channel. This technique could be used on any equipment using tubular galvanometer light sources.

  10. Using Remote Sensing and High-Resolution Digital Elevation Models to Identify Potential Erosional Hotspots Along River Channels During High Discharge Storm Events

    Science.gov (United States)

    Orland, E. D.; Amidon, W. H.

    2017-12-01

    As global warming intensifies, large precipitation events and associated floods are becoming increasingly common. Channel adjustments during floods can occur by both erosion and deposition of sediment, often damaging infrastructure in the process. There is thus a need for predictive models that can help managers identify river reaches that are most prone to adjustment during storms. Because rivers in post-glacial landscapes often flow over a mixture of bedrock and alluvial substrates, the identification of bedrock vs. alluvial channel reaches is an important first step in predicting vulnerability to channel adjustment during flood events, especially because bedrock channels are unlikely to adjust significantly, even during floods. This study develops a semi-automated approach to predicting channel substrate using a high-resolution LiDAR-derived digital elevation model (DEM). The study area is the Middlebury River in Middlebury, VT-a well-studied watershed with a wide variety of channel substrates, including reaches with documented channel adjustments during recent flooding events. Multiple metrics were considered for reference—such as channel width and drainage area—but the study utilized channel slope as a key parameter for identifying morphological variations within the Middlebury River. Using data extracted from the DEM, a power law was fit to selected slope and drainage area values for each branch in order to model idealized slope-drainage area relationships, which were then compared with measured slope-drainage area relationships. Differences in measured slope minus predicted slope (called delta-slope) are shown to help predict river channel substrate. Compared with field observations, higher delta-slope values correlate with more stable, boulder rich channels or bedrock gorges; conversely the lowest delta-slope values correlate with flat, sediment rich alluvial channels. The delta-slope metric thus serves as a reliable first-order predictor of channel

  11. Multimode Interference: Identifying Channels and Ridges in Quantum Probability Distributions

    OpenAIRE

    O'Connell, Ross C.; Loinaz, Will

    2004-01-01

    The multimode interference technique is a simple way to study the interference patterns found in many quantum probability distributions. We demonstrate that this analysis not only explains the existence of so-called "quantum carpets," but can explain the spatial distribution of channels and ridges in the carpets. With an understanding of the factors that govern these channels and ridges we have a limited ability to produce a particular pattern of channels and ridges by carefully choosing the ...

  12. Path lumping: An efficient algorithm to identify metastable path channels for conformational dynamics of multi-body systems

    Science.gov (United States)

    Meng, Luming; Sheong, Fu Kit; Zeng, Xiangze; Zhu, Lizhe; Huang, Xuhui

    2017-07-01

    Constructing Markov state models from large-scale molecular dynamics simulation trajectories is a promising approach to dissect the kinetic mechanisms of complex chemical and biological processes. Combined with transition path theory, Markov state models can be applied to identify all pathways connecting any conformational states of interest. However, the identified pathways can be too complex to comprehend, especially for multi-body processes where numerous parallel pathways with comparable flux probability often coexist. Here, we have developed a path lumping method to group these parallel pathways into metastable path channels for analysis. We define the similarity between two pathways as the intercrossing flux between them and then apply the spectral clustering algorithm to lump these pathways into groups. We demonstrate the power of our method by applying it to two systems: a 2D-potential consisting of four metastable energy channels and the hydrophobic collapse process of two hydrophobic molecules. In both cases, our algorithm successfully reveals the metastable path channels. We expect this path lumping algorithm to be a promising tool for revealing unprecedented insights into the kinetic mechanisms of complex multi-body processes.

  13. Identifying functional reorganization of spelling networks: an individual peak probability comparison approach

    Science.gov (United States)

    Purcell, Jeremy J.; Rapp, Brenda

    2013-01-01

    Previous research has shown that damage to the neural substrates of orthographic processing can lead to functional reorganization during reading (Tsapkini et al., 2011); in this research we ask if the same is true for spelling. To examine the functional reorganization of spelling networks we present a novel three-stage Individual Peak Probability Comparison (IPPC) analysis approach for comparing the activation patterns obtained during fMRI of spelling in a single brain-damaged individual with dysgraphia to those obtained in a set of non-impaired control participants. The first analysis stage characterizes the convergence in activations across non-impaired control participants by applying a technique typically used for characterizing activations across studies: Activation Likelihood Estimate (ALE) (Turkeltaub et al., 2002). This method was used to identify locations that have a high likelihood of yielding activation peaks in the non-impaired participants. The second stage provides a characterization of the degree to which the brain-damaged individual's activations correspond to the group pattern identified in Stage 1. This involves performing a Mahalanobis distance statistics analysis (Tsapkini et al., 2011) that compares each of a control group's peak activation locations to the nearest peak generated by the brain-damaged individual. The third stage evaluates the extent to which the brain-damaged individual's peaks are atypical relative to the range of individual variation among the control participants. This IPPC analysis allows for a quantifiable, statistically sound method for comparing an individual's activation pattern to the patterns observed in a control group and, thus, provides a valuable tool for identifying functional reorganization in a brain-damaged individual with impaired spelling. Furthermore, this approach can be applied more generally to compare any individual's activation pattern with that of a set of other individuals. PMID:24399981

  14. Control channels in the brain and their influence on brain executive functions

    Science.gov (United States)

    Meng, Qinglei; Choa, Fow-Sen; Hong, Elliot; Wang, Zhiguang; Islam, Mohammad

    2014-05-01

    In a computer network there are distinct data channels and control channels where massive amount of visual information are transported through data channels but the information streams are routed and controlled by intelligent algorithm through "control channels". Recent studies on cognition and consciousness have shown that the brain control channels are closely related to the brainwave beta (14-40 Hz) and alpha (7-13 Hz) oscillations. The high-beta wave is used by brain to synchronize local neural activities and the alpha oscillation is for desynchronization. When two sensory inputs are simultaneously presented to a person, the high-beta is used to select one of the inputs and the alpha is used to deselect the other so that only one input will get the attention. In this work we demonstrated that we can scan a person's brain using binaural beats technique and identify the individual's preferred control channels. The identified control channels can then be used to influence the subject's brain executive functions. In the experiment, an EEG measurement system was used to record and identify a subject's control channels. After these channels were identified, the subject was asked to do Stroop tests. Binaural beats was again used to produce these control-channel frequencies on the subject's brain when we recorded the completion time of each test. We found that the high-beta signal indeed speeded up the subject's executive function performance and reduced the time to complete incongruent tests, while the alpha signal didn't seem to be able to slow down the executive function performance.

  15. Functional connectome fingerprinting: identifying individuals using patterns of brain connectivity.

    Science.gov (United States)

    Finn, Emily S; Shen, Xilin; Scheinost, Dustin; Rosenberg, Monica D; Huang, Jessica; Chun, Marvin M; Papademetris, Xenophon; Constable, R Todd

    2015-11-01

    Functional magnetic resonance imaging (fMRI) studies typically collapse data from many subjects, but brain functional organization varies between individuals. Here we establish that this individual variability is both robust and reliable, using data from the Human Connectome Project to demonstrate that functional connectivity profiles act as a 'fingerprint' that can accurately identify subjects from a large group. Identification was successful across scan sessions and even between task and rest conditions, indicating that an individual's connectivity profile is intrinsic, and can be used to distinguish that individual regardless of how the brain is engaged during imaging. Characteristic connectivity patterns were distributed throughout the brain, but the frontoparietal network emerged as most distinctive. Furthermore, we show that connectivity profiles predict levels of fluid intelligence: the same networks that were most discriminating of individuals were also most predictive of cognitive behavior. Results indicate the potential to draw inferences about single subjects on the basis of functional connectivity fMRI.

  16. Measuring individual work performance: identifying and selecting indicators.

    Science.gov (United States)

    Koopmans, Linda; Bernaards, Claire M; Hildebrandt, Vincent H; de Vet, Henrica C W; van der Beek, Allard J

    2014-01-01

    Theoretically, individual work performance (IWP) can be divided into four dimensions: task performance, contextual performance, adaptive performance, and counterproductive work behavior. However, there is no consensus on the indicators used to measure these dimensions. This study was designed to (1) identify indicators for each dimension, (2) select the most relevant indicators, and (3) determine the relative weight of each dimension in ratings of work performance. IWP indicators were identified from multiple research disciplines, via literature, existing questionnaires, and expert interviews. Subsequently, experts selected the most relevant indicators per dimension and scored the relative weight of each dimension in ratings of IWP. In total, 128 unique indicators were identified. Twenty-three of these indicators were selected by experts as most relevant for measuring IWP. Task performance determined 36% of the work performance rating, while the other three dimensions respectively determined 22%, 20% and 21% of the rating. Notable consensus was found on relevant indicators of IWP, reducing the number from 128 to 23 relevant indicators. This provides an important step towards the development of a standardized, generic and short measurement instrument for assessing IWP.

  17. 47 CFR 90.615 - Individual channels available in the General Category in 806-824/851-869 MHz band.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Individual channels available in the General Category in 806-824/851-869 MHz band. 90.615 Section 90.615 Telecommunication FEDERAL COMMUNICATIONS... Critical Infrastructure Industry Categories from three to five years after the release of a public notice...

  18. Identifying influential individuals on intensive care units: using cluster analysis to explore culture.

    Science.gov (United States)

    Fong, Allan; Clark, Lindsey; Cheng, Tianyi; Franklin, Ella; Fernandez, Nicole; Ratwani, Raj; Parker, Sarah Henrickson

    2017-07-01

    The objective of this paper is to identify attribute patterns of influential individuals in intensive care units using unsupervised cluster analysis. Despite the acknowledgement that culture of an organisation is critical to improving patient safety, specific methods to shift culture have not been explicitly identified. A social network analysis survey was conducted and an unsupervised cluster analysis was used. A total of 100 surveys were gathered. Unsupervised cluster analysis was used to group individuals with similar dimensions highlighting three general genres of influencers: well-rounded, knowledge and relational. Culture is created locally by individual influencers. Cluster analysis is an effective way to identify common characteristics among members of an intensive care unit team that are noted as highly influential by their peers. To change culture, identifying and then integrating the influencers in intervention development and dissemination may create more sustainable and effective culture change. Additional studies are ongoing to test the effectiveness of utilising these influencers to disseminate patient safety interventions. This study offers an approach that can be helpful in both identifying and understanding influential team members and may be an important aspect of developing methods to change organisational culture. © 2017 John Wiley & Sons Ltd.

  19. Selection of Inhibitor-Resistant Viral Potassium Channels Identifies a Selectivity Filter Site that Affects Barium and Amantadine Block

    Science.gov (United States)

    Fujiwara, Yuichiro; Arrigoni, Cristina; Domigan, Courtney; Ferrara, Giuseppina; Pantoja, Carlos; Thiel, Gerhard; Moroni, Anna; Minor, Daniel L.

    2009-01-01

    Background Understanding the interactions between ion channels and blockers remains an important goal that has implications for delineating the basic mechanisms of ion channel function and for the discovery and development of ion channel directed drugs. Methodology/Principal Findings We used genetic selection methods to probe the interaction of two ion channel blockers, barium and amantadine, with the miniature viral potassium channel Kcv. Selection for Kcv mutants that were resistant to either blocker identified a mutant bearing multiple changes that was resistant to both. Implementation of a PCR shuffling and backcrossing procedure uncovered that the blocker resistance could be attributed to a single change, T63S, at a position that is likely to form the binding site for the inner ion in the selectivity filter (site 4). A combination of electrophysiological and biochemical assays revealed a distinct difference in the ability of the mutant channel to interact with the blockers. Studies of the analogous mutation in the mammalian inward rectifier Kir2.1 show that the T→S mutation affects barium block as well as the stability of the conductive state. Comparison of the effects of similar barium resistant mutations in Kcv and Kir2.1 shows that neighboring amino acids in the Kcv selectivity filter affect blocker binding. Conclusions/Significance The data support the idea that permeant ions have an integral role in stabilizing potassium channel structure, suggest that both barium and amantadine act at a similar site, and demonstrate how genetic selections can be used to map blocker binding sites and reveal mechanistic features. PMID:19834614

  20. Individually identifiable body odors are produced by the gorilla and discriminated by humans.

    Science.gov (United States)

    Hepper, Peter G; Wells, Deborah L

    2010-05-01

    Many species produce odor cues that enable them to be identified individually, as well as providing other socially relevant information. Study of the role of odor cues in the social behavior of great apes is noticeable by its absence. Olfaction has been viewed as having little role in guiding behavior in these species. This study examined whether Western lowland gorillas produce an individually identifiable odor. Odor samples were obtained by placing cloths in the gorilla's den. A delayed matching to sample task was used with human participants (n = 100) to see if they were able to correctly match a target odor sample to a choice of either: 2 odors (the target sample and another, Experiment 1) and 6 odors (the target sample and 5 others, Experiment 2). Participants were correctly able to identify the target odor when given either 2 or 6 matches. Subjects made fewest errors when matching the odor of the silverback, whereas matching the odors of the young gorillas produced most errors. The results indicate that gorillas do produce individually identifiable body odors and introduce the possibility that odor cues may play a role in gorilla social behavior.

  1. PedMine – A simulated annealing algorithm to identify maximally unrelated individuals in population isolates

    OpenAIRE

    Douglas, Julie A.; Sandefur, Conner I.

    2008-01-01

    In family-based genetic studies, it is often useful to identify a subset of unrelated individuals. When such studies are conducted in population isolates, however, most if not all individuals are often detectably related to each other. To identify a set of maximally unrelated (or equivalently, minimally related) individuals, we have implemented simulated annealing, a general-purpose algorithm for solving difficult combinatorial optimization problems. We illustrate our method on data from a ge...

  2. Bat wing biometrics: using collagen–elastin bundles in bat wings as a unique individual identifier

    Science.gov (United States)

    Sybill K. Amelon; Sarah E. Hooper; Kathryn M. Womack

    2017-01-01

    The ability to recognize individuals within an animal population is fundamental to conservation and management. Identification of individual bats has relied on artificial marking techniques that may negatively affect the survival and alter the behavior of individuals. Biometric systems use biological characteristics to identify individuals. The field of animal...

  3. Identifying transition rates of ionic channels via observations at a single state

    CERN Document Server

    Deng Ying Chun; Qian Min Ping; Feng Jian Feng

    2003-01-01

    We consider how to determine all transition rates of an ion channel when it can be described by a birth-death chain or a Markov chain on a star-graph with continuous time. It is found that all transition rates are uniquely determined by the distribution of its lifetime and death-time histograms at a single state. An algorithm to calculate the transition rates exactly, based on the statistics of the lifetime and death-time of the Markov chain at the state, is provided. Examples to illustrate how an ion channel activity is fully determined by the observation of a single state of the ion channel are included.

  4. Identifying transition rates of ionic channels via observations at a single state

    International Nuclear Information System (INIS)

    Deng Yingchun; Peng Shenglun; Qian Minping; Feng Jianfeng

    2003-01-01

    We consider how to determine all transition rates of an ion channel when it can be described by a birth-death chain or a Markov chain on a star-graph with continuous time. It is found that all transition rates are uniquely determined by the distribution of its lifetime and death-time histograms at a single state. An algorithm to calculate the transition rates exactly, based on the statistics of the lifetime and death-time of the Markov chain at the state, is provided. Examples to illustrate how an ion channel activity is fully determined by the observation of a single state of the ion channel are included

  5. Identifying transition rates of ionic channels via observations at a single state

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yingchun [School of Mathematics, Peking University, Beijing (China); Peng Shenglun [School of Mathematics, Peking University, Beijing (China); Qian Minping [School of Mathematics, Peking University, Beijing (China); Feng Jianfeng [COGS, Sussex University, Brighton (United Kingdom)

    2003-02-07

    We consider how to determine all transition rates of an ion channel when it can be described by a birth-death chain or a Markov chain on a star-graph with continuous time. It is found that all transition rates are uniquely determined by the distribution of its lifetime and death-time histograms at a single state. An algorithm to calculate the transition rates exactly, based on the statistics of the lifetime and death-time of the Markov chain at the state, is provided. Examples to illustrate how an ion channel activity is fully determined by the observation of a single state of the ion channel are included.

  6. Triple-channel portable capillary electrophoresis instrument with individual background electrolytes for the concurrent separations of anionic and cationic species

    Energy Technology Data Exchange (ETDEWEB)

    Mai, Thanh Duc; Le, Minh Duc [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Sáiz, Jorge [Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Ctra. Madrid-Barcelona Km 33.6, Alcalá de Henares, Madrid (Spain); Duong, Hong Anh [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Koenka, Israel Joel [University of Basel, Department of Chemistry, Spitalstrasse 51, 4056 Basel (Switzerland); Pham, Hung Viet, E-mail: phamhungviet@hus.edu.vn [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Hauser, Peter C., E-mail: Peter.Hauser@unibas.ch [University of Basel, Department of Chemistry, Spitalstrasse 51, 4056 Basel (Switzerland)

    2016-03-10

    The portable capillary electrophoresis instrument is automated and features three independent channels with different background electrolytes to allow the concurrent optimized determination of three different categories of charged analytes. The fluidic system is based on a miniature manifold which is based on mechanically milled channels for injection of samples and buffers. The planar manifold pattern was designed to minimize the number of electronic valves required for each channel. The system utilizes pneumatic pressurization to transport solutions at the grounded as well as the high voltage side of the separation capillaries. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 (w) × 35 (d) × 15 cm (h) and a weight of about 15 kg. It can operate continuously for 8 h in the battery-powered mode if only one electrophoresis channel is in use, or for about 2.5 h in the case of simultaneous employment of all three channels. The different operations, i.e. capillary flushing, rinsing of the interfaces at both capillary ends, sample injection and electrophoretic separation, are activated automatically with a control program featuring a graphical user interface. For demonstration, the system was employed successfully for the concurrent separation of different inorganic cations and anions, organic preservatives, additives and artificial sweeteners in various beverage and food matrices. - Highlights: • The use of parallel channels allows the concurrent separation of different classes of analytes. • Separate background electrolytes allow individual optimization. • The instrument is compact and field portable.

  7. Triple-channel portable capillary electrophoresis instrument with individual background electrolytes for the concurrent separations of anionic and cationic species

    International Nuclear Information System (INIS)

    Mai, Thanh Duc; Le, Minh Duc; Sáiz, Jorge; Duong, Hong Anh; Koenka, Israel Joel; Pham, Hung Viet; Hauser, Peter C.

    2016-01-01

    The portable capillary electrophoresis instrument is automated and features three independent channels with different background electrolytes to allow the concurrent optimized determination of three different categories of charged analytes. The fluidic system is based on a miniature manifold which is based on mechanically milled channels for injection of samples and buffers. The planar manifold pattern was designed to minimize the number of electronic valves required for each channel. The system utilizes pneumatic pressurization to transport solutions at the grounded as well as the high voltage side of the separation capillaries. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 (w) × 35 (d) × 15 cm (h) and a weight of about 15 kg. It can operate continuously for 8 h in the battery-powered mode if only one electrophoresis channel is in use, or for about 2.5 h in the case of simultaneous employment of all three channels. The different operations, i.e. capillary flushing, rinsing of the interfaces at both capillary ends, sample injection and electrophoretic separation, are activated automatically with a control program featuring a graphical user interface. For demonstration, the system was employed successfully for the concurrent separation of different inorganic cations and anions, organic preservatives, additives and artificial sweeteners in various beverage and food matrices. - Highlights: • The use of parallel channels allows the concurrent separation of different classes of analytes. • Separate background electrolytes allow individual optimization. • The instrument is compact and field portable.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Stavis, Samuel M [Ithaca, NY; Edel, Joshua B [Brookline, MA; Samiee, Kevan T [Ithaca, NY; Craighead, Harold G [Ithaca, NY

    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.

  11. Chronnectome fingerprinting: Identifying individuals and predicting higher cognitive functions using dynamic brain connectivity patterns.

    Science.gov (United States)

    Liu, Jin; Liao, Xuhong; Xia, Mingrui; He, Yong

    2018-02-01

    The human brain is a large, interacting dynamic network, and its architecture of coupling among brain regions varies across time (termed the "chronnectome"). However, very little is known about whether and how the dynamic properties of the chronnectome can characterize individual uniqueness, such as identifying individuals as a "fingerprint" of the brain. Here, we employed multiband resting-state functional magnetic resonance imaging data from the Human Connectome Project (N = 105) and a sliding time-window dynamic network analysis approach to systematically examine individual time-varying properties of the chronnectome. We revealed stable and remarkable individual variability in three dynamic characteristics of brain connectivity (i.e., strength, stability, and variability), which was mainly distributed in three higher order cognitive systems (i.e., default mode, dorsal attention, and fronto-parietal) and in two primary systems (i.e., visual and sensorimotor). Intriguingly, the spatial patterns of these dynamic characteristics of brain connectivity could successfully identify individuals with high accuracy and could further significantly predict individual higher cognitive performance (e.g., fluid intelligence and executive function), which was primarily contributed by the higher order cognitive systems. Together, our findings highlight that the chronnectome captures inherent functional dynamics of individual brain networks and provides implications for individualized characterization of health and disease. © 2017 Wiley Periodicals, Inc.

  12. Bat wing biometrics: using collagen–elastin bundles in bat wings as a unique individual identifier

    Science.gov (United States)

    Hooper, Sarah E.; Womack, Kathryn M.

    2017-01-01

    Abstract The ability to recognize individuals within an animal population is fundamental to conservation and management. Identification of individual bats has relied on artificial marking techniques that may negatively affect the survival and alter the behavior of individuals. Biometric systems use biological characteristics to identify individuals. The field of animal biometrics has expanded to include recognition of individuals based upon various morphologies and phenotypic variations including pelage patterns, tail flukes, and whisker arrangement. Biometric systems use 4 biologic measurement criteria: universality, distinctiveness, permanence, and collectability. Additionally, the system should not violate assumptions of capture–recapture methods that include no increased mortality or alterations of behavior. We evaluated whether individual bats could be uniquely identified based upon the collagen–elastin bundles that are visible with gross examination of their wings. We examined little brown bats (Myotis lucifugus), northern long-eared bats (M. septentrionalis), big brown bats (Eptesicus fuscus), and tricolored bats (Perimyotis subflavus) to determine whether the “wing prints” from the bundle network would satisfy the biologic measurement criteria. We evaluated 1,212 photographs from 230 individual bats comparing week 0 photos with those taken at weeks 3 or 6 and were able to confirm identity of individuals over time. Two blinded evaluators were able to successfully match 170 individuals in hand to photographs taken at weeks 0, 3, and 6. This study suggests that bats can be successfully re-identified using photographs taken at previous times. We suggest further evaluation of this methodology for use in a standardized system that can be shared among bat conservationists. PMID:29674784

  13. Bat wing biometrics: using collagen-elastin bundles in bat wings as a unique individual identifier.

    Science.gov (United States)

    Amelon, Sybill K; Hooper, Sarah E; Womack, Kathryn M

    2017-05-29

    The ability to recognize individuals within an animal population is fundamental to conservation and management. Identification of individual bats has relied on artificial marking techniques that may negatively affect the survival and alter the behavior of individuals. Biometric systems use biological characteristics to identify individuals. The field of animal biometrics has expanded to include recognition of individuals based upon various morphologies and phenotypic variations including pelage patterns, tail flukes, and whisker arrangement. Biometric systems use 4 biologic measurement criteria: universality, distinctiveness, permanence, and collectability. Additionally, the system should not violate assumptions of capture-recapture methods that include no increased mortality or alterations of behavior. We evaluated whether individual bats could be uniquely identified based upon the collagen-elastin bundles that are visible with gross examination of their wings. We examined little brown bats ( Myotis lucifugus ), northern long-eared bats ( M. septentrionalis ), big brown bats ( Eptesicus fuscus ), and tricolored bats ( Perimyotis subflavus ) to determine whether the "wing prints" from the bundle network would satisfy the biologic measurement criteria. We evaluated 1,212 photographs from 230 individual bats comparing week 0 photos with those taken at weeks 3 or 6 and were able to confirm identity of individuals over time. Two blinded evaluators were able to successfully match 170 individuals in hand to photographs taken at weeks 0, 3, and 6. This study suggests that bats can be successfully re-identified using photographs taken at previous times. We suggest further evaluation of this methodology for use in a standardized system that can be shared among bat conservationists.

  14. Selective spider toxins reveal a role for Nav1.1 channel in mechanical pain

    OpenAIRE

    Osteen, Jeremiah D.; Herzig, Volker; Gilchrist, John; Emrick, Joshua J.; Zhang, Chuchu; Wang, Xidao; Castro, Joel; Garcia-Caraballo, Sonia; Grundy, Luke; Rychkov, Grigori Y.; Weyer, Andy D.; Dekan, Zoltan; Undheim, Eivind A. B.; Alewood, Paul; Stucky, Cheryl L.

    2016-01-01

    Voltage-gated sodium (Nav) channels initiate action potentials in most neurons, including primary afferent nerve fibers of the pain pathway. Local anesthetics block pain through non-specific actions at all Nav channels, but the discovery of selective modulators would facilitate the analysis of individual subtypes and their contributions to chemical, mechanical, or thermal pain. Here, we identify and characterize spider toxins that selectively activate the Nav1.1 subtype, whose role in nocicep...

  15. Multi-channel imaging cytometry with a single detector

    Science.gov (United States)

    Locknar, Sarah; Barton, John; Entwistle, Mark; Carver, Gary; Johnson, Robert

    2018-02-01

    Multi-channel microscopy and multi-channel flow cytometry generate high bit data streams. Multiple channels (both spectral and spatial) are important in diagnosing diseased tissue and identifying individual cells. Omega Optical has developed techniques for mapping multiple channels into the time domain for detection by a single high gain, high bandwidth detector. This approach is based on pulsed laser excitation and a serial array of optical fibers coated with spectral reflectors such that up to 15 wavelength bins are sequentially detected by a single-element detector within 2.5 μs. Our multichannel microscopy system uses firmware running on dedicated DSP and FPGA chips to synchronize the laser, scanning mirrors, and sampling clock. The signals are digitized by an NI board into 14 bits at 60MHz - allowing for 232 by 174 pixel fields in up to 15 channels with 10x over sampling. Our multi-channel imaging cytometry design adds channels for forward scattering and back scattering to the fluorescence spectral channels. All channels are detected within the 2.5 μs - which is compatible with fast cytometry. Going forward, we plan to digitize at 16 bits with an A-toD chip attached to a custom board. Processing these digital signals in custom firmware would allow an on-board graphics processing unit to display imaging flow cytometry data over configurable scanning line lengths. The scatter channels can be used to trigger data buffering when a cell is present in the beam. This approach enables a low cost mechanically robust imaging cytometer.

  16. Identifying real and perceived barriers to therapeutic education programs for individuals with inflammatory arthritis.

    Science.gov (United States)

    Bain, Lorna; Sangrar, Ruheena; Bornstein, Carolyn; Lukmanji, Sara; Hapuhennedige, Sandani; Thorne, Carter; Beattie, Karen A

    2016-09-01

    Therapeutic Education Programs (TEPs) grounded in self-management principles have been shown to improve quality of life of patients with chronic conditions and reduce patient-related healthcare costs. Though these programs are becoming more readily available, patients often experience barriers in participating. This study sought to identify barriers faced by inflammatory arthritis (IA) patients in attending a TEP and understand how patients overcame perceived barriers. A mixed-method study design was used. Questionnaires were distributed to individuals with IA who were invited to attend a TEP between 2010 and 2013. Respondents were those that chose not to attend (group A), individuals who attended ≤4 of 10 sessions (group B), individuals who attended ≥5 of 10 sessions prior to May 2013 (group C), and individuals who attended ≥5 of 10 sessions from June 2013 to November 2013 (group D). Individuals in group D were also invited to participate in focus groups to discuss how they had overcome perceived barriers. Real barriers identified by individuals in groups A and B included time, distance, and cost associated with attendance. Individuals who overcame perceived barriers (groups C and D) discussed strategies they used to do so. Aspects of the overall program experience and access to clinic and program also contributed to patients being able to overcome barriers. Time, distance, and cost are external barriers that prevented individuals from utilizing self-management education opportunities. These barriers were overcome if and when individuals had resources available to them. Readiness for behavior change also influenced commitment to participate in the program.

  17. Identification and characterization of Ca2+-activated K+ channels in granulosa cells of the human ovary

    Directory of Open Access Journals (Sweden)

    Berg Ulrike

    2009-04-01

    Full Text Available Abstract Background Granulosa cells (GCs represent a major endocrine compartment of the ovary producing sex steroid hormones. Recently, we identified in human GCs a Ca2+-activated K+ channel (KCa of big conductance (BKCa, which is involved in steroidogenesis. This channel is activated by intraovarian signalling molecules (e.g. acetylcholine via raised intracellular Ca2+ levels. In this study, we aimed at characterizing 1. expression and functions of KCa channels (including BKCa beta-subunits, and 2. biophysical properties of BKCa channels. Methods GCs were obtained from in vitro-fertilization patients and cultured. Expression of mRNA was determined by standard RT-PCR and protein expression in human ovarian slices was detected by immunohistochemistry. Progesterone production was measured in cell culture supernatants using ELISAs. Single channels were recorded in the inside-out configuration of the patch-clamp technique. Results We identified two KCa types in human GCs, the intermediate- (IK and the small-conductance KCa (SK. Their functionality was concluded from attenuation of human chorionic gonadotropin-stimulated progesterone production by KCa blockers (TRAM-34, apamin. Functional IK channels were also demonstrated by electrophysiological recording of single KCa channels with distinctive features. Both, IK and BKCa channels were found to be simultaneously active in individual GCs. In agreement with functional data, we identified mRNAs encoding IK, SK1, SK2 and SK3 in human GCs and proteins of IK and SK2 in corresponding human ovarian cells. Molecular characterization of the BKCa channel revealed the presence of mRNAs encoding several BKCa beta-subunits (beta2, beta3, beta4 in human GCs. The multitude of beta-subunits detected might contribute to variations in Ca2+ dependence of individual BKCa channels which we observed in electrophysiological recordings. Conclusion Functional and molecular studies indicate the presence of active IK and SK

  18. Expert and crowd-sourced validation of an individualized sleep spindle detection method employing complex demodulation and individualized normalization

    Directory of Open Access Journals (Sweden)

    Laura eRay

    2015-09-01

    Full Text Available A spindle detection method was developed that: 1 extracts the signal of interest (i.e., spindle-related phasic changes in sigma relative to ongoing background sigma activity using complex demodulation, 2 accounts for variations of spindle characteristics across the night, scalp derivations and between individuals, and 3 employs a minimum number of sometimes arbitrary, user-defined parameters. Complex demodulation was used to extract instantaneous power in the spindle band. To account for intra- and inter-individual differences, the signal was z-score transformed using a 60s sliding window, per channel, over the course of the recording. Spindle events were detected with a z-score threshold corresponding to a low probability (e.g., 99th percentile. Spindle characteristics, such as amplitude, duration and oscillatory frequency, were derived for each individual spindle following detection, which permits spindles to be subsequently and flexibly categorized as slow or fast spindles from a single detection pass. Spindles were automatically detected in 15 young healthy subjects. Two experts manually identified spindles from C3 during Stage 2 sleep, from each recording; one employing conventional guidelines, and the other, identifying spindles with the aid of a sigma (11-16 Hz filtered channel. These spindles were then compared between raters and to the automated detection to identify the presence of true positives, true negatives, false positives and false negatives. This method of automated spindle detection resolves or avoids many of the limitations that complicate automated spindle detection, and performs well compared to a group of non-experts, and importantly, has good external validity with respect to the extant literature in terms of the characteristics of automatically detected spindles.

  19. Use of Photogrammetry and Biomechanical Gait analysis to Identify Individuals

    DEFF Research Database (Denmark)

    Larsen, Peter Kastmand; Simonsen, Erik Bruun; Lynnerup, Niels

    Photogrammetry and recognition of gait patterns are valuable tools to help identify perpetrators based on surveillance recordings. We have found that stature but only few other measures have a satisfying reproducibility for use in forensics. Several gait variables with high recognition rates were...... found. Especially the variables located in the frontal plane are interesting due to large inter-individual differences in time course patterns. The variables with high recognition rates seem preferable for use in forensic gait analysis and as input variables to waveform analysis techniques...

  20. Ion channels in plants.

    Science.gov (United States)

    Hedrich, Rainer

    2012-10-01

    Since the first recordings of single potassium channel activities in the plasma membrane of guard cells more than 25 years ago, patch-clamp studies discovered a variety of ion channels in all cell types and plant species under inspection. Their properties differed in a cell type- and cell membrane-dependent manner. Guard cells, for which the existence of plant potassium channels was initially documented, advanced to a versatile model system for studying plant ion channel structure, function, and physiology. Interestingly, one of the first identified potassium-channel genes encoding the Shaker-type channel KAT1 was shown to be highly expressed in guard cells. KAT1-type channels from Arabidopsis thaliana and its homologs from other species were found to encode the K(+)-selective inward rectifiers that had already been recorded in early patch-clamp studies with guard cells. Within the genome era, additional Arabidopsis Shaker-type channels appeared. All nine members of the Arabidopsis Shaker family are localized at the plasma membrane, where they either operate as inward rectifiers, outward rectifiers, weak voltage-dependent channels, or electrically silent, but modulatory subunits. The vacuole membrane, in contrast, harbors a set of two-pore K(+) channels. Just very recently, two plant anion channel families of the SLAC/SLAH and ALMT/QUAC type were identified. SLAC1/SLAH3 and QUAC1 are expressed in guard cells and mediate Slow- and Rapid-type anion currents, respectively, that are involved in volume and turgor regulation. Anion channels in guard cells and other plant cells are key targets within often complex signaling networks. Here, the present knowledge is reviewed for the plant ion channel biology. Special emphasis is drawn to the molecular mechanisms of channel regulation, in the context of model systems and in the light of evolution.

  1. Individual human scent as a forensic identifier using mantrailing.

    Science.gov (United States)

    Woidtke, Leif; Dreßler, Jan; Babian, Carsten

    2018-01-01

    Specially trained dogs have long been used by law enforcement agencies to help in criminal investigations and in searching for missing persons. Still, it is unclear which components of human scent released into the environment contribute to successful searches of individuals. In this study, saliva and axillary sweat samples were taken from a total of 190 people. Additionally, DNA was extracted from whole blood of seven different people and used as an odour sample as well. Overall 675 tests (trails) were performed during a period of 18 months. The ability to track individuals with the odour samples mentioned above was examined with seven dogs, four of which were specially-trained dogs (mantrailer) from the Saxony Police. Results indicated that specially-trained police dogs can track a person with an average success rate of 82% and correctly identify the absence of an odour track with an average success rate of 97% under various conditions. Private rescue dogs were less successful with an average success rate of 65% and 75% respectively. These data suggest that the potential error rate of a well-trained handler team is low and can be a useful tool for law enforcement personnel. Saliva, as a reference odour source, was found to be particularly suitable for the search. The results of the study suggest that the components contained in axillary sweat, saliva and DNA extracted from whole blood are sufficient, serving as a key stimulus for individualized searches. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Ankle brachial index, C-reactive protein, and central augmentation index to identify individuals with severe atherosclerosis

    DEFF Research Database (Denmark)

    Eldrup, Nikolaj; Sillesen, Henrik; Prescott, Eva

    2006-01-01

    We examined the ability of ankle brachial index, C-reactive protein and central augmentation index to identify individuals in the general population with severe atherosclerosis, diagnosed as those with ischaemic cardiovascular disease.......We examined the ability of ankle brachial index, C-reactive protein and central augmentation index to identify individuals in the general population with severe atherosclerosis, diagnosed as those with ischaemic cardiovascular disease....

  3. Potassium channels in brain mitochondria.

    Science.gov (United States)

    Bednarczyk, Piotr

    2009-01-01

    Potassium channels are the most widely distributed class of ion channels. These channels are transmembrane proteins known to play important roles in both normal and pathophysiological functions in all cell types. Various potassium channels are recognised as potential therapeutic targets in the treatment of Parkinson's disease, Alzheimer's disease, brain/spinal cord ischaemia and sepsis. In addition to their importance as therapeutic targets, certain potassium channels are known for their beneficial roles in anaesthesia, cardioprotection and neuroprotection. Some types of potassium channels present in the plasma membrane of various cells have been found in the inner mitochondrial membrane as well. Potassium channels have been proposed to regulate mitochondrial membrane potential, respiration, matrix volume and Ca(+) ion homeostasis. It has been proposed that mitochondrial potassium channels mediate ischaemic preconditioning in various tissues. However, the specificity of a pharmacological agents and the mechanisms underlying their effects on ischaemic preconditioning remain controversial. The following potassium channels from various tissues have been identified in the inner mitochondrial membrane: ATP-regulated (mitoK(ATP)) channel, large conductance Ca(2+)-regulated (mitoBK(Ca)) channel, intermediate conductance Ca(2+)-regulated (mitoIK(Ca)) channel, voltage-gated (mitoKv1.3 type) channel, and twin-pore domain (mitoTASK-3) channel. It has been shown that increased potassium flux into brain mitochondria induced by either the mitoK(ATP) channel or mitoBK(Ca) channel affects the beneficial effects on neuronal cell survival under pathological conditions. Recently, differential distribution of mitoBK(Ca) channels has been observed in neuronal mitochondria. These findings may suggest a neuroprotective role for the mitoBK(Ca) channel in specific brain structures. This minireview summarises current data on brain mitochondrial potassium channels and the efforts to identify

  4. Consideration of hot channel factors in design for providing operating margins on coolant channel outlet temperature

    International Nuclear Information System (INIS)

    Sharma, V.K.; Surendar, C.; Bapat, C.N.

    1994-01-01

    The Indian Pressurized Heavy Water Reactors (IPHWR) are horizontal pressure tube reactors using natural uranium oxide fuel in the form of short (495 mm) clusters. The fuel clusters in the Zr-Nb pressure tubes are cooled by high pressure, high temperature and subcooled circulating heavy water. Coolant flow distribution to individual channels is designed to match the power distribution so as to obtain uniform coolant outlet temperature. However, during operation, the coolant outlet temperature in individual channels deviate from their nominal value due to: tolerances in process design; effects of grid frequency on the pump speed; deviation in channel powers from the nominal values due to on-power fuelling and movement of reactivity devices, and so on. Thus an operating margin, between the highest permissible and nominal coolant outlet temperatures, is required taking into account various hot channel factors that contribute to higher coolant outlet temperatures. The paper discusses the methodology adopted to assess various hot channel factors which would provide optimum operating margins while ensuring sub-cooling. (author)

  5. Needles in the haystack: identifying individuals present in pooled genomic data.

    Directory of Open Access Journals (Sweden)

    Rosemary Braun

    2009-10-01

    Full Text Available Recent publications have described and applied a novel metric that quantifies the genetic distance of an individual with respect to two population samples, and have suggested that the metric makes it possible to infer the presence of an individual of known genotype in a sample for which only the marginal allele frequencies are known. However, the assumptions, limitations, and utility of this metric remained incompletely characterized. Here we present empirical tests of the method using publicly accessible genotypes, as well as analytical investigations of the method's strengths and limitations. The results reveal that the null distribution is sensitive to the underlying assumptions, making it difficult to accurately calibrate thresholds for classifying an individual as a member of the population samples. As a result, the false-positive rates obtained in practice are considerably higher than previously believed. However, despite the metric's inadequacies for identifying the presence of an individual in a sample, our results suggest potential avenues for future research on tuning this method to problems of ancestry inference or disease prediction. By revealing both the strengths and limitations of the proposed method, we hope to elucidate situations in which this distance metric may be used in an appropriate manner. We also discuss the implications of our findings in forensics applications and in the protection of GWAS participant privacy.

  6. Characterizing Social Networks and Communication Channels in a Web-Based Peer Support Intervention.

    Science.gov (United States)

    Owen, Jason E; Curran, Michaela; Bantum, Erin O'Carroll; Hanneman, Robert

    2016-06-01

    Web and mobile (mHealth) interventions have promise for improving health outcomes, but engagement and attrition may be reducing effect sizes. Because social networks can improve engagement, which is a key mechanism of action, understanding the structure and potential impact of social networks could be key to improving mHealth effects. This study (a) evaluates social network characteristics of four distinct communication channels (discussion board, chat, e-mail, and blog) in a large social networking intervention, (b) predicts membership in online communities, and (c) evaluates whether community membership impacts engagement. Participants were 299 cancer survivors with significant distress using the 12-week health-space.net intervention. Social networking attributes (e.g., density and clustering) were identified separately for each type of network communication (i.e., discussion board, blog, web mail, and chat). Each channel demonstrated high levels of clustering, and being a community member in one communication channel was associated with being in the same community in each of the other channels (φ = 0.56-0.89, ps < 0.05). Predictors of community membership differed across communication channels, suggesting that each channel reached distinct types of users. Finally, membership in a discussion board, chat, or blog community was strongly associated with time spent engaging with coping skills exercises (Ds = 1.08-1.84, ps < 0.001) and total time of intervention (Ds = 1.13-1.80, ps < 0.001). mHealth interventions that offer multiple channels for communication allow participants to expand the number of individuals with whom they are communicating, create opportunities for communicating with different individuals in distinct channels, and likely enhance overall engagement.

  7. Characterizing Social Networks and Communication Channels in a Web-Based Peer Support Intervention

    Science.gov (United States)

    Curran, Michaela; Bantum, Erin O'Carroll; Hanneman, Robert

    2016-01-01

    Abstract Web and mobile (mHealth) interventions have promise for improving health outcomes, but engagement and attrition may be reducing effect sizes. Because social networks can improve engagement, which is a key mechanism of action, understanding the structure and potential impact of social networks could be key to improving mHealth effects. This study (a) evaluates social network characteristics of four distinct communication channels (discussion board, chat, e-mail, and blog) in a large social networking intervention, (b) predicts membership in online communities, and (c) evaluates whether community membership impacts engagement. Participants were 299 cancer survivors with significant distress using the 12-week health-space.net intervention. Social networking attributes (e.g., density and clustering) were identified separately for each type of network communication (i.e., discussion board, blog, web mail, and chat). Each channel demonstrated high levels of clustering, and being a community member in one communication channel was associated with being in the same community in each of the other channels (φ = 0.56–0.89, ps < 0.05). Predictors of community membership differed across communication channels, suggesting that each channel reached distinct types of users. Finally, membership in a discussion board, chat, or blog community was strongly associated with time spent engaging with coping skills exercises (Ds = 1.08–1.84, ps < 0.001) and total time of intervention (Ds = 1.13–1.80, ps < 0.001). mHealth interventions that offer multiple channels for communication allow participants to expand the number of individuals with whom they are communicating, create opportunities for communicating with different individuals in distinct channels, and likely enhance overall engagement. PMID:27327066

  8. Identifying cochlear implant channels with poor electrode-neuron interface: electrically-evoked auditory brainstem responses measured with the partial tripolar configuration

    Science.gov (United States)

    Bierer, Julie Arenberg; Faulkner, Kathleen F.; Tremblay, Kelly L.

    2011-01-01

    obtained with both the monopolar and partial tripolar configurations. The Wave V amplitude growth functions with increasing stimulus level showed the predicted effect of shallower growth for the partial tripolar than for the monopolar configuration, but this was observed only for the low threshold channel. In contrast, high-threshold channels showed the opposite effect; steeper growth functions were seen for the partial tripolar configuration. Conclusions These results suggest that behavioral thresholds or EABRs measured with a restricted stimulus can be used to identify potentially impaired cochlear implant channels. Channels having high thresholds and steep growth functions would likely not activate the appropriate spatially restricted region of the cochlea, leading to suboptimal perception. As a clinical tool, quick identification of impaired channels could lead to patient-specific mapping strategies and result in improved speech and music perception. PMID:21178633

  9. Pharmacological modulation of SK3 channels

    DEFF Research Database (Denmark)

    Grunnet, M; Jespersen, Thomas; Angelo, K

    2001-01-01

    Small-conductance, calcium-activated K+ channels (SK channels) are voltage-insensitive channels that have been identified molecularly within the last few years. As SK channels play a fundamental role in most excitable cells and participate in afterhyperpolarization (AHP) and spike-frequency adapt...... at concentrations of 3 microM and above. Amitriptyline, a tricyclic antidepressive widely used clinically, inhibits SK3 channels with an IC50 of 39.1 +/- 10 microM (n=6)....

  10. Mechanosensitive Channels: In Touch with Piezo

    OpenAIRE

    Xiao, Rui; Xu, X.Z. Shawn

    2010-01-01

    Mechanosensory transduction underlies touch, hearing and proprioception and requires mechanosensitive channels that are directly gated by forces; however, the molecular identities of these channels remain largely elusive. A new study has identified Piezo1 and Piezo2 as a novel class of mechanosensitive channels.

  11. Individual variation and hormonal modulation of a sodium channel beta subunit in the electric organ correlate with variation in a social signal.

    Science.gov (United States)

    Liu, He; Wu, Ming-Ming; Zakon, Harold H

    2007-09-01

    The sodium channel beta1 subunit affects sodium channel gating and surface density, but little is known about the factors that regulate beta1 expression or its participation in the fine control of cellular excitability. In this study we examined whether graded expression of the beta1 subunit contributes to the gradient in sodium current inactivation, which is tightly controlled and directly related to a social behavior, the electric organ discharge (EOD), in a weakly electric fish Sternopygus macrurus. We found the mRNA and protein levels of beta1 in the electric organ both correlate with EOD frequency. We identified a novel mRNA splice form of this gene and found the splicing preference for this novel splice form also correlates with EOD frequency. Androgen implants lowered EOD frequency and decreased the beta1 mRNA level but did not affect splicing. Coexpression of each splice form in Xenopus oocytes with either the human muscle sodium channel gene, hNav1.4, or a Sternopygus ortholog, smNav1.4b, sped the rate of inactivation of the sodium current and shifted the steady-state inactivation toward less negative membrane potentials. The translational product of the novel mRNA splice form lacks a previously identified important tyrosine residue but still functions normally. The properties of the fish alpha and coexpressed beta1 subunits in the oocyte replicate those of the electric organ's endogenous sodium current. These data highlight the role of ion channel beta subunits in regulating cellular excitability.

  12. Channel identification machines.

    Science.gov (United States)

    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.

  13. Channel Identification Machines

    Directory of Open Access Journals (Sweden)

    Aurel A. Lazar

    2012-01-01

    Full Text Available 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.

  14. Quantum incompatibility of channels with general outcome operator algebras

    Science.gov (United States)

    Kuramochi, Yui

    2018-04-01

    A pair of quantum channels is said to be incompatible if they cannot be realized as marginals of a single channel. This paper addresses the general structure of the incompatibility of completely positive channels with a fixed quantum input space and with general outcome operator algebras. We define a compatibility relation for such channels by identifying the composite outcome space as the maximal (projective) C*-tensor product of outcome algebras. We show theorems that characterize this compatibility relation in terms of the concatenation and conjugation of channels, generalizing the recent result for channels with quantum outcome spaces. These results are applied to the positive operator valued measures (POVMs) by identifying each of them with the corresponding quantum-classical (QC) channel. We also give a characterization of the maximality of a POVM with respect to the post-processing preorder in terms of the conjugate channel of the QC channel. We consider another definition of compatibility of normal channels by identifying the composite outcome space with the normal tensor product of the outcome von Neumann algebras. We prove that for a given normal channel, the class of normally compatible channels is upper bounded by a special class of channels called tensor conjugate channels. We show the inequivalence of the C*- and normal compatibility relations for QC channels, which originates from the possibility and impossibility of copying operations for commutative von Neumann algebras in C*- and normal compatibility relations, respectively.

  15. Identifying cochlear implant channels with poor electrode-neuron interfaces: electrically evoked auditory brain stem responses measured with the partial tripolar configuration.

    Science.gov (United States)

    Bierer, Julie Arenberg; Faulkner, Kathleen F; Tremblay, Kelly L

    2011-01-01

    tripolar configurations. The Wave V amplitude growth functions with increasing stimulus level showed the predicted effect of shallower growth for the partial tripolar than for the monopolar configuration, but this was observed only for the low-threshold channels. In contrast, high-threshold channels showed the opposite effect; steeper growth functions were seen for the partial tripolar configuration. These results suggest that behavioral thresholds or EABRs measured with a restricted stimulus can be used to identify potentially impaired cochlear implant channels. Channels having high thresholds and steep growth functions would likely not activate the appropriate spatially restricted region of the cochlea, leading to suboptimal perception. As a clinical tool, quick identification of impaired channels could lead to patient-specific mapping strategies and result in improved speech and music perception.

  16. A survey of pyrethroid-resistant populations of Meligethes aeneus F. in Poland indicates the incidence of numerous substitutions in the pyrethroid target site of voltage-sensitive sodium channels in individual beetles.

    Science.gov (United States)

    Wrzesińska, B; Czerwoniec, A; Wieczorek, P; Węgorek, P; Zamojska, J; Obrępalska-Stęplowska, A

    2014-10-01

    The pollen beetle (Meligethes aeneus F.) is the most devastating pest of oilseed rape (Brassica napus) and is controlled by pyrethroid insecticides. However, resistance to pyrethroids in Europe is becoming widespread and predominant. Pyrethroids target the voltage-sensitive sodium channel (VSSC), and mutations in VSSC may be responsible for pyrethroid insensitivity. Here, we analysed individual beetles that were resistant to esfenvalerate, a pyrethroid, from 14 populations that were collected from oilseed rape fields in Poland. We screened the VSSC domains that were presumed to directly interact with pyrethroids. We identified 18 heterozygous nucleic acid substitutions, amongst which six caused an amino acid change: N912S, G926S, I936V, R957G, F1538L and E1553G. Our analysis of the three-dimensional structure of these domains in VSSC revealed that some of these changes may slightly influence the protein structure and hence the docking efficiency of esfenvalerate. Therefore, these mutations may impact the susceptibility of the sodium channel to the action of this insecticide. © 2014 The Royal Entomological Society.

  17. Why individual thermo sensation and pain perception varies? Clue of disruptive mutations in TRPVs from 2504 human genome data.

    Science.gov (United States)

    Ghosh, Arijit; Kaur, Navneet; Kumar, Abhishek; Goswami, Chandan

    2016-09-02

    Every individual varies in character and so do their sensory functions and perceptions. The molecular mechanism and the molecular candidates involved in these processes are assumed to be similar if not same. So far several molecular factors have been identified which are fairly conserved across the phylogenetic tree and are involved in these complex sensory functions. Among all, members belonging to Transient Receptor Potential (TRP) channels have been widely characterized for their involvement in thermo-sensation. These include TRPV1 to TRPV4 channels which reveal complex thermo-gating behavior in response to changes in temperature. The molecular evolution of these channels is highly correlative with the thermal response of different species. However, recent 2504 human genome data suggest that these thermo-sensitive TRPV channels are highly variable and carry possible deleterious mutations in human population. These unexpected findings may explain the individual differences in terms of complex sensory functions.

  18. Electrophysiological characterisation of KCNQ channel modulators

    DEFF Research Database (Denmark)

    Schrøder, R.L

    Potassium (K+) ion channels are ubiquitously expressed in mammalian cells, and each channel serves a precise physiological role due to its specific biophysical characteristics and expression pattern. A few K+ channels are targets for certain drugs, and in this thesis it is suggested that the KCNQ K......+ channels may be targets for neuroprotective, anti-epileptic and anti-nociceptive compounds. The importance of these channels is underscored by the fact that four out of five KCNQ channel subtypes are involved in severe human diseases. However, the pharmacology of the KCNQ channels is yet poorly understood...... as these channels were identified only recently. Therefore, there is a need for understanding the biophysical behavior and pharmacology of these ion channels. KCNQ channels belong to the group of voltage-activated K+ channels. The subfamily consists of KCNQ1-5, which is primarily expressed in the CNS, heart, ear...

  19. Defect imaging and channeling studies using channeling scanning transmission ion microscopy

    NARCIS (Netherlands)

    King, PJC; Breese, MBH; Smulders, PJM; Wilshaw, PR; Grime, GW

    The technique of channeling scanning transmission ion microscopy (CSTIM) can be used to produce images of individual crystal defects (such as dislocations and stacking faults) using the scanned, focused ion beam from a nuclear microprobe. As well as offering a new method for studies of crystal

  20. The Human Genome Project and Eugenics: Identifying the Impact on Individuals with Mental Retardation.

    Science.gov (United States)

    Kuna, Jason

    2001-01-01

    This article explores the impact of the mapping work of the Human Genome Project on individuals with mental retardation and the negative effects of genetic testing. The potential to identify disabilities and the concept of eugenics are discussed, along with ethical issues surrounding potential genetic therapies. (Contains references.) (CR)

  1. Decoding the attended speech stream with multi-channel EEG: implications for online, daily-life applications

    Science.gov (United States)

    Mirkovic, Bojana; Debener, Stefan; Jaeger, Manuela; De Vos, Maarten

    2015-08-01

    Objective. Recent studies have provided evidence that temporal envelope driven speech decoding from high-density electroencephalography (EEG) and magnetoencephalography recordings can identify the attended speech stream in a multi-speaker scenario. The present work replicated the previous high density EEG study and investigated the necessary technical requirements for practical attended speech decoding with EEG. Approach. Twelve normal hearing participants attended to one out of two simultaneously presented audiobook stories, while high density EEG was recorded. An offline iterative procedure eliminating those channels contributing the least to decoding provided insight into the necessary channel number and optimal cross-subject channel configuration. Aiming towards the future goal of near real-time classification with an individually trained decoder, the minimum duration of training data necessary for successful classification was determined by using a chronological cross-validation approach. Main results. Close replication of the previously reported results confirmed the method robustness. Decoder performance remained stable from 96 channels down to 25. Furthermore, for less than 15 min of training data, the subject-independent (pre-trained) decoder performed better than an individually trained decoder did. Significance. Our study complements previous research and provides information suggesting that efficient low-density EEG online decoding is within reach.

  2. Identifying the Correlates and Barriers of Future Planning among Parents of Individuals with Intellectual and Developmental Disabilities

    Science.gov (United States)

    Burke, Meghan; Arnold, Catherine; Owen, Aleksa

    2018-01-01

    Although individuals with intellectual and developmental disabilities (IDD) are living longer lives, fewer than half of parents of individuals with IDD conduct future planning. The correlates and barriers to future planning must be identified to develop targeted interventions to facilitate future planning. In this study, 388 parents of individuals…

  3. Use of navigation channels by Lake Sturgeon: Does channelization increase vulnerability of fish to ship strikes?

    Directory of Open Access Journals (Sweden)

    Darryl W Hondorp

    Full Text Available Channelization for navigation and flood control has altered the hydrology and bathymetry of many large rivers with unknown consequences for fish species that undergo riverine migrations. In this study, we investigated whether altered flow distributions and bathymetry associated with channelization attracted migrating Lake Sturgeon (Acipenser fulvescens into commercial navigation channels, potentially increasing their exposure to ship strikes. To address this question, we quantified and compared Lake Sturgeon selection for navigation channels vs. alternative pathways in two multi-channel rivers differentially affected by channelization, but free of barriers to sturgeon movement. Acoustic telemetry was used to quantify Lake Sturgeon movements. Under the assumption that Lake Sturgeon navigate by following primary flow paths, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River were expected to choose navigation channels over alternative pathways and to exhibit greater selection for navigation channels than conspecifics in the less-channelized lower St. Clair River. Consistent with these predictions, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River selected the higher-flow and deeper navigation channels over alternative migration pathways, whereas in the less-channelized lower St. Clair River, individuals primarily used pathways alternative to navigation channels. Lake Sturgeon selection for navigation channels as migratory pathways also was significantly higher in the more-channelized lower Detroit River than in the less-channelized lower St. Clair River. We speculated that use of navigation channels over alternative pathways would increase the spatial overlap of commercial vessels and migrating Lake Sturgeon, potentially enhancing their vulnerability to ship strikes. Results of our study thus demonstrated an association between channelization and the path use of migrating Lake Sturgeon that could prove

  4. Cl- channels in apoptosis

    DEFF Research Database (Denmark)

    Wanitchakool, Podchanart; Ousingsawat, Jiraporn; Sirianant, Lalida

    2016-01-01

    A remarkable feature of apoptosis is the initial massive cell shrinkage, which requires opening of ion channels to allow release of K(+), Cl(-), and organic osmolytes to drive osmotic water movement and cell shrinkage. This article focuses on the role of the Cl(-) channels LRRC8, TMEM16/anoctamin......, and cystic fibrosis transmembrane conductance regulator (CFTR) in cellular apoptosis. LRRC8A-E has been identified as a volume-regulated anion channel expressed in many cell types. It was shown to be required for regulatory and apoptotic volume decrease (RVD, AVD) in cultured cell lines. Its presence also......(-) channels or as regulators of other apoptotic Cl(-) channels, such as LRRC8. CFTR has been known for its proapoptotic effects for some time, and this effect may be based on glutathione release from the cell and increase in cytosolic reactive oxygen species (ROS). Although we find that CFTR is activated...

  5. Spatial channel interactions in cochlear implants

    Science.gov (United States)

    Tang, Qing; Benítez, Raul; Zeng, Fan-Gang

    2011-08-01

    The modern multi-channel cochlear implant is widely considered to be the most successful neural prosthesis owing to its ability to restore partial hearing to post-lingually deafened adults and to allow essentially normal language development in pre-lingually deafened children. However, the implant performance varies greatly in individuals and is still limited in background noise, tonal language understanding, and music perception. One main cause for the individual variability and the limited performance in cochlear implants is spatial channel interaction from the stimulating electrodes to the auditory nerve and brain. Here we systematically examined spatial channel interactions at the physical, physiological, and perceptual levels in the same five modern cochlear implant subjects. The physical interaction was examined using an electric field imaging technique, which measured the voltage distribution as a function of the electrode position in the cochlea in response to the stimulation of a single electrode. The physiological interaction was examined by recording electrically evoked compound action potentials as a function of the electrode position in response to the stimulation of the same single electrode position. The perceptual interactions were characterized by changes in detection threshold as well as loudness summation in response to in-phase or out-of-phase dual-electrode stimulation. To minimize potentially confounding effects of temporal factors on spatial channel interactions, stimulus rates were limited to 100 Hz or less in all measurements. Several quantitative channel interaction indexes were developed to define and compare the width, slope and symmetry of the spatial excitation patterns derived from these physical, physiological and perceptual measures. The electric field imaging data revealed a broad but uniformly asymmetrical intracochlear electric field pattern, with the apical side producing a wider half-width and shallower slope than the basal

  6. Ca2+-dependent K+ Channels in Exocrine Salivary Glands

    Science.gov (United States)

    Catalán, Marcelo A.; Peña-Munzenmayer, Gaspar; Melvin, James E.

    2014-01-01

    In the last 15 years, remarkable progress has been realized in identifying the genes that encode the ion-transporting proteins involved in exocrine gland function, including salivary glands. Among these proteins, Ca2+-dependent K+ channels take part in key functions including membrane potential regulation, fluid movement and K+ secretion in exocrine glands. Two K+ channels have been identified in exocrine salivary glands: 1) a Ca2+-activated K+ channel of intermediate single channel conductance encoded by the KCNN4 gene; and, 2) a voltage- and Ca2+-dependent K+ channel of large single channel conductance encoded by the KCNMA1 gene. This review focuses on the physiological roles of Ca2+-dependent K+ channels in exocrine salivary glands. We also discuss interesting recent findings on the regulation of Ca2+-dependent K+ channels by protein-protein interactions that may significantly impact exocrine gland physiology. PMID:24559652

  7. Distinctive fingerprints of erosional regimes in terrestrial channel networks

    Science.gov (United States)

    Grau Galofre, A.; Jellinek, M.

    2017-12-01

    Satellite imagery and digital elevation maps capture the large scale morphology of channel networks attributed to long term erosional processes, such as fluvial, glacial, groundwater sapping and subglacial erosion. Characteristic morphologies associated with each of these styles of erosion have been studied in detail, but there exists a knowledge gap related to their parameterization and quantification. This knowledge gap prevents a rigorous analysis of the dominant processes that shaped a particular landscape, and a comparison across styles of erosion. To address this gap, we use previous morphological descriptions of glaciers, rivers, sapping valleys and tunnel valleys to identify and measure quantitative metrics diagnostic of these distinctive styles of erosion. From digital elevation models, we identify four geometric metrics: The minimum channel width, channel aspect ratio (longest length to channel width at the outlet), presence of undulating longitudinal profiles, and tributary junction angle. We also parameterize channel network complexity in terms of its stream order and fractal dimension. We then perform a statistical classification of the channel networks using a Principal Component Analysis on measurements of these six metrics on a dataset of 70 channelized systems. We show that rivers, glaciers, groundwater seepage and subglacial meltwater erode the landscape in rigorously distinguishable ways. Our methodology can more generally be applied to identify the contributions of different processes involved in carving a channel network. In particular, we are able to identify transitions from fluvial to glaciated landscapes or vice-versa.

  8. Channel Bottom Morphology in the Deltaic Reach of the Song Hau (mekong) River Channel in Vietnam

    Science.gov (United States)

    Allison, M. A.; Weathers, H. D., III; Meselhe, E. A.

    2016-02-01

    Boat-based, channel bathymetry and bankline elevation studies were conducted in the tidal and estuarine Mekong River channel using multibeam bathymetry and LIDAR corrected for elevation by RTK satellite positioning. Two mapping campaigns, one at high discharge in October 2014 and one at low discharge in March 2015, were conducted in the lower 100 km reach of the Song Hau distributary channel to (1) examine bottom morphology and its relationship to sediment transport, and (2) to provide information to setup the grid for a multi-dimensional and reduced complexity models of channel hydrodynamics and sediment dynamics. Sand fields were identified in multibeam data by the presence of dunes that were as large as 2-4 m high and 40-80 m wavelength and by clean sands in bottom grabs. Extensive areas of sand at the head and toe of mid-channel islands displayed 10-25 m diameter circular pits that could be correlated with bucket dredge, sand mining activities observed at some of the sites. Large areas of the channel floor were relict (containing little or no modern sediment) in the high discharge campaign, identifiable by the presence of along channel erosional furrows and terraced outcrops along the channel floor and margins. Laterally extensive flat areas were also observed in the channel thalweg. Both these and the relict areas were sampled by bottom grab as stiff silty clays. Complex cross-channel combinations of these morphologies were observed in some transects, suggesting strong bottom steering of tidal and riverine currents. Relative to high discharge, transects above and below the salt penetration limit showed evidence of shallowing in the thalweg and adjacent sloping areas at low discharge in March 2015. This shallowing, combined with the reduced extent of sand fields and furrowed areas, and soft muds in grabs, suggests seasonal trapping of fine grained sediment is occurring by estuarine and tidal circulation.

  9. Plant ion channels: gene families, physiology, and functional genomics analyses.

    Science.gov (United States)

    Ward, John M; Mäser, Pascal; Schroeder, Julian I

    2009-01-01

    Distinct potassium, anion, and calcium channels in the plasma membrane and vacuolar membrane of plant cells have been identified and characterized by patch clamping. Primarily owing to advances in Arabidopsis genetics and genomics, and yeast functional complementation, many of the corresponding genes have been identified. Recent advances in our understanding of ion channel genes that mediate signal transduction and ion transport are discussed here. Some plant ion channels, for example, ALMT and SLAC anion channel subunits, are unique. The majority of plant ion channel families exhibit homology to animal genes; such families include both hyperpolarization- and depolarization-activated Shaker-type potassium channels, CLC chloride transporters/channels, cyclic nucleotide-gated channels, and ionotropic glutamate receptor homologs. These plant ion channels offer unique opportunities to analyze the structural mechanisms and functions of ion channels. Here we review gene families of selected plant ion channel classes and discuss unique structure-function aspects and their physiological roles in plant cell signaling and transport.

  10. Identification of discriminant proteins through antibody profiling, methods and apparatus for identifying an individual

    Science.gov (United States)

    Thompson, Vicki S; Lacey, Jeffrey A; Gentillon, Cynthia A; Apel, William A

    2015-03-03

    A method for determining a plurality of proteins for discriminating and positively identifying an individual based from a biological sample. The method may include profiling a biological sample from a plurality of individuals against a protein array including a plurality of proteins. The protein array may include proteins attached to a support in a preselected pattern such that locations of the proteins are known. The biological sample may be contacted with the protein array such that a portion of antibodies in the biological sample reacts with and binds to the proteins forming immune complexes. A statistical analysis method, such as discriminant analysis, may be performed to determine discriminating proteins for distinguishing individuals. Proteins of interest may be used to form a protein array. Such a protein array may be used, for example, to compare a forensic sample from an unknown source with a sample from a known source.

  11. Identification of discriminant proteins through antibody profiling, methods and apparatus for identifying an individual

    Energy Technology Data Exchange (ETDEWEB)

    Apel, William A.; Thompson, Vicki S; Lacey, Jeffrey A.; Gentillon, Cynthia A.

    2016-08-09

    A method for determining a plurality of proteins for discriminating and positively identifying an individual based from a biological sample. The method may include profiling a biological sample from a plurality of individuals against a protein array including a plurality of proteins. The protein array may include proteins attached to a support in a preselected pattern such that locations of the proteins are known. The biological sample may be contacted with the protein array such that a portion of antibodies in the biological sample reacts with and binds to the proteins forming immune complexes. A statistical analysis method, such as discriminant analysis, may be performed to determine discriminating proteins for distinguishing individuals. Proteins of interest may be used to form a protein array. Such a protein array may be used, for example, to compare a forensic sample from an unknown source with a sample from a known source.

  12. Sour ageusia in two individuals implicates ion channels of the ASIC and PKD families in human sour taste perception at the anterior tongue.

    Directory of Open Access Journals (Sweden)

    Taufiqul Huque

    2009-10-01

    Full Text Available The perception of sour taste in humans is incompletely understood at the receptor cell level. We report here on two patients with an acquired sour ageusia. Each patient was unresponsive to sour stimuli, but both showed normal responses to bitter, sweet, and salty stimuli.Lingual fungiform papillae, containing taste cells, were obtained by biopsy from the two patients, and from three sour-normal individuals, and analyzed by RT-PCR. The following transcripts were undetectable in the patients, even after 50 cycles of amplification, but readily detectable in the sour-normal subjects: acid sensing ion channels (ASICs 1a, 1beta, 2a, 2b, and 3; and polycystic kidney disease (PKD channels PKD1L3 and PKD2L1. Patients and sour-normals expressed the taste-related phospholipase C-beta2, the delta-subunit of epithelial sodium channel (ENaC and the bitter receptor T2R14, as well as beta-actin. Genomic analysis of one patient, using buccal tissue, did not show absence of the genes for ASIC1a and PKD2L1. Immunohistochemistry of fungiform papillae from sour-normal subjects revealed labeling of taste bud cells by antibodies to ASICs 1a and 1beta, PKD2L1, phospholipase C-beta2, and delta-ENaC. An antibody to PKD1L3 labeled tissue outside taste bud cells.These data suggest a role for ASICs and PKDs in human sour perception. This is the first report of sour ageusia in humans, and the very existence of such individuals ("natural knockouts" suggests a cell lineage for sour that is independent of the other taste modalities.

  13. Analysis of individual cells identifies cell-to-cell variability following induction of cellular senescence.

    Science.gov (United States)

    Wiley, Christopher D; Flynn, James M; Morrissey, Christapher; Lebofsky, Ronald; Shuga, Joe; Dong, Xiao; Unger, Marc A; Vijg, Jan; Melov, Simon; Campisi, Judith

    2017-10-01

    Senescent cells play important roles in both physiological and pathological processes, including cancer and aging. In all cases, however, senescent cells comprise only a small fraction of tissues. Senescent phenotypes have been studied largely in relatively homogeneous populations of cultured cells. In vivo, senescent cells are generally identified by a small number of markers, but whether and how these markers vary among individual cells is unknown. We therefore utilized a combination of single-cell isolation and a nanofluidic PCR platform to determine the contributions of individual cells to the overall gene expression profile of senescent human fibroblast populations. Individual senescent cells were surprisingly heterogeneous in their gene expression signatures. This cell-to-cell variability resulted in a loss of correlation among the expression of several senescence-associated genes. Many genes encoding senescence-associated secretory phenotype (SASP) factors, a major contributor to the effects of senescent cells in vivo, showed marked variability with a subset of highly induced genes accounting for the increases observed at the population level. Inflammatory genes in clustered genomic loci showed a greater correlation with senescence compared to nonclustered loci, suggesting that these genes are coregulated by genomic location. Together, these data offer new insights into how genes are regulated in senescent cells and suggest that single markers are inadequate to identify senescent cells in vivo. © 2017 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  14. A CONCISE PANEL OF BIOMARKERS IDENTIFIES NEUROCOGNITIVE FUNCTIONING CHANGES IN HIV-INFECTED INDIVIDUALS

    Science.gov (United States)

    Marcotte, Thomas D.; Deutsch, Reena; Michael, Benedict Daniel; Franklin, Donald; Cookson, Debra Rosario; Bharti, Ajay R.; Grant, Igor; Letendre, Scott L.

    2013-01-01

    Background Neurocognitive (NC) impairment (NCI) occurs commonly in people living with HIV. Despite substantial effort, no biomarkers have been sufficiently validated for diagnosis and prognosis of NCI in the clinic. The goal of this project was to identify diagnostic or prognostic biomarkers for NCI in a comprehensively characterized HIV cohort. Methods Multidisciplinary case review selected 98 HIV-infected individuals and categorized them into four NC groups using normative data: stably normal (SN), stably impaired (SI), worsening (Wo), or improving (Im). All subjects underwent comprehensive NC testing, phlebotomy, and lumbar puncture at two timepoints separated by a median of 6.2 months. Eight biomarkers were measured in CSF and blood by immunoassay. Results were analyzed using mixed model linear regression and staged recursive partitioning. Results At the first visit, subjects were mostly middle-aged (median 45) white (58%) men (84%) who had AIDS (70%). Of the 73% who took antiretroviral therapy (ART), 54% had HIV RNA levels below 50 c/mL in plasma. Mixed model linear regression identified that only MCP-1 in CSF was associated with neurocognitive change group. Recursive partitioning models aimed at diagnosis (i.e., correctly classifying neurocognitive status at the first visit) were complex and required most biomarkers to achieve misclassification limits. In contrast, prognostic models were more efficient. A combination of three biomarkers (sCD14, MCP-1, SDF-1α) correctly classified 82% of Wo and SN subjects, including 88% of SN subjects. A combination of two biomarkers (MCP-1, TNF-α) correctly classified 81% of Im and SI subjects, including 100% of SI subjects. Conclusions This analysis of well-characterized individuals identified concise panels of biomarkers associated with NC change. Across all analyses, the two most frequently identified biomarkers were sCD14 and MCP-1, indicators of monocyte/macrophage activation. While the panels differed depending on

  15. Beltless translocation domain of botulinum neurotoxin A embodies a minimum ion-conductive channel.

    Science.gov (United States)

    Fischer, Audrey; Sambashivan, Shilpa; Brunger, Axel T; Montal, Mauricio

    2012-01-13

    Botulinum neurotoxin, the causative agent of the paralytic disease botulism, is an endopeptidase composed of a catalytic domain (or light chain (LC)) and a heavy chain (HC) encompassing the translocation domain (TD) and receptor-binding domain. Upon receptor-mediated endocytosis, the LC and TD are proposed to undergo conformational changes in the acidic endocytic environment resulting in the formation of an LC protein-conducting TD channel. The mechanism of channel formation and the conformational changes in the toxin upon acidification are important but less well understood aspects of botulinum neurotoxin intoxication. Here, we have identified a minimum channel-forming truncation of the TD, the "beltless" TD, that forms transmembrane channels with ion conduction properties similar to those of the full-length TD. At variance with the holotoxin and the HC, channel formation for both the TD and the beltless TD occurs independent of a transmembrane pH gradient. Furthermore, acidification in solution induces moderate secondary structure changes. The subtle nature of the conformational changes evoked by acidification on the TD suggests that, in the context of the holotoxin, larger structural rearrangements and LC unfolding occur preceding or concurrent to channel formation. This notion is consistent with the hypothesis that although each domain of the holotoxin functions individually, each domain serves as a chaperone for the others.

  16. Post-Translational Modifications of TRP Channels

    Directory of Open Access Journals (Sweden)

    Olaf Voolstra

    2014-04-01

    Full Text Available Transient receptor potential (TRP channels constitute an ancient family of cation channels that have been found in many eukaryotic organisms from yeast to human. TRP channels exert a multitude of physiological functions ranging from Ca2+ homeostasis in the kidney to pain reception and vision. These channels are activated by a wide range of stimuli and undergo covalent post-translational modifications that affect and modulate their subcellular targeting, their biophysical properties, or channel gating. These modifications include N-linked glycosylation, protein phosphorylation, and covalent attachment of chemicals that reversibly bind to specific cysteine residues. The latter modification represents an unusual activation mechanism of ligand-gated ion channels that is in contrast to the lock-and-key paradigm of receptor activation by its agonists. In this review, we summarize the post-translational modifications identified on TRP channels and, when available, explain their physiological role.

  17. Identifying individuals at high risk of psychosis: predictive utility of Support Vector Machine using structural and functional MRI data

    Directory of Open Access Journals (Sweden)

    Isabel eValli

    2016-04-01

    Full Text Available The identification of individuals at high risk of developing psychosis is entirely based on clinical assessment, associated with limited predictive potential. There is therefore increasing interest in the development of biological markers that could be used in clinical practice for this purpose. We studied 25 individuals with an At Risk Mental State for psychosis and 25 healthy controls using structural MRI, and functional MRI in conjunction with a verbal memory task. Data were analysed using a standard univariate analysis, and with Support Vector Machine (SVM, a multivariate pattern recognition technique that enables statistical inferences to be made at the level of the individual, yielding results with high translational potential. The application of SVM to structural MRI data permitted the identification of individuals at high risk of psychosis with a sensitivity of 68% and a specificity of 76%, resulting in an accuracy of 72% (p<0.001. Univariate volumetric between-group differences did not reach statistical significance. In contrast, the univariate fMRI analysis identified between-group differences (p<0.05 corrected while the application of SVM to the same data did not. Since SVM is well suited at identifying the pattern of abnormality that distinguishes two groups, whereas univariate methods are more likely to identify regions that individually are most different between two groups, our results suggest the presence of focal functional abnormalities in the context of a diffuse pattern of structural abnormalities in individuals at high clinical risk of psychosis.

  18. A quantized mechanism for activation of pannexin channels

    Science.gov (United States)

    Chiu, Yu-Hsin; Jin, Xueyao; Medina, Christopher B.; Leonhardt, Susan A.; Kiessling, Volker; Bennett, Brad C.; Shu, Shaofang; Tamm, Lukas K.; Yeager, Mark; Ravichandran, Kodi S.; Bayliss, Douglas A.

    2017-01-01

    Pannexin 1 (PANX1) subunits form oligomeric plasma membrane channels that mediate nucleotide release for purinergic signalling, which is involved in diverse physiological processes such as apoptosis, inflammation, blood pressure regulation, and cancer progression and metastasis. Here we explore the mechanistic basis for PANX1 activation by using wild type and engineered concatemeric channels. We find that PANX1 activation involves sequential stepwise sojourns through multiple discrete open states, each with unique channel gating and conductance properties that reflect contributions of the individual subunits of the hexamer. Progressive PANX1 channel opening is directly linked to permeation of ions and large molecules (ATP and fluorescent dyes) and occurs during both irreversible (caspase cleavage-mediated) and reversible (α1 adrenoceptor-mediated) forms of channel activation. This unique, quantized activation process enables fine tuning of PANX1 channel activity and may be a generalized regulatory mechanism for other related multimeric channels. PMID:28134257

  19. Ion channel expression patterns in glioblastoma stem cells with functional and therapeutic implications for malignancy.

    Directory of Open Access Journals (Sweden)

    Julia Pollak

    Full Text Available Ion channels and transporters have increasingly recognized roles in cancer progression through the regulation of cell proliferation, migration, and death. Glioblastoma stem-like cells (GSCs are a source of tumor formation and recurrence in glioblastoma multiforme, a highly aggressive brain cancer, suggesting that ion channel expression may be perturbed in this population. However, little is known about the expression and functional relevance of ion channels that may contribute to GSC malignancy. Using RNA sequencing, we assessed the enrichment of ion channels in GSC isolates and non-tumor neural cell types. We identified a unique set of GSC-enriched ion channels using differential expression analysis that is also associated with distinct gene mutation signatures. In support of potential clinical relevance, expression of selected GSC-enriched ion channels evaluated in human glioblastoma databases of The Cancer Genome Atlas and Ivy Glioblastoma Atlas Project correlated with patient survival times. Finally, genetic knockdown as well as pharmacological inhibition of individual or classes of GSC-enriched ion channels constrained growth of GSCs compared to normal neural stem cells. This first-in-kind global examination characterizes ion channels enriched in GSCs and explores their potential clinical relevance to glioblastoma molecular subtypes, gene mutations, survival outcomes, regional tumor expression, and experimental responses to loss-of-function. Together, the data support the potential biological and therapeutic impact of ion channels on GSC malignancy and provide strong rationale for further examination of their mechanistic and therapeutic importance.

  20. Ion channel expression patterns in glioblastoma stem cells with functional and therapeutic implications for malignancy.

    Science.gov (United States)

    Pollak, Julia; Rai, Karan G; Funk, Cory C; Arora, Sonali; Lee, Eunjee; Zhu, Jun; Price, Nathan D; Paddison, Patrick J; Ramirez, Jan-Marino; Rostomily, Robert C

    2017-01-01

    Ion channels and transporters have increasingly recognized roles in cancer progression through the regulation of cell proliferation, migration, and death. Glioblastoma stem-like cells (GSCs) are a source of tumor formation and recurrence in glioblastoma multiforme, a highly aggressive brain cancer, suggesting that ion channel expression may be perturbed in this population. However, little is known about the expression and functional relevance of ion channels that may contribute to GSC malignancy. Using RNA sequencing, we assessed the enrichment of ion channels in GSC isolates and non-tumor neural cell types. We identified a unique set of GSC-enriched ion channels using differential expression analysis that is also associated with distinct gene mutation signatures. In support of potential clinical relevance, expression of selected GSC-enriched ion channels evaluated in human glioblastoma databases of The Cancer Genome Atlas and Ivy Glioblastoma Atlas Project correlated with patient survival times. Finally, genetic knockdown as well as pharmacological inhibition of individual or classes of GSC-enriched ion channels constrained growth of GSCs compared to normal neural stem cells. This first-in-kind global examination characterizes ion channels enriched in GSCs and explores their potential clinical relevance to glioblastoma molecular subtypes, gene mutations, survival outcomes, regional tumor expression, and experimental responses to loss-of-function. Together, the data support the potential biological and therapeutic impact of ion channels on GSC malignancy and provide strong rationale for further examination of their mechanistic and therapeutic importance.

  1. [Predicting individual risk of high healthcare cost to identify complex chronic patients].

    Science.gov (United States)

    Coderch, Jordi; Sánchez-Pérez, Inma; Ibern, Pere; Carreras, Marc; Pérez-Berruezo, Xavier; Inoriza, José M

    2014-01-01

    To develop a predictive model for the risk of high consumption of healthcare resources, and assess the ability of the model to identify complex chronic patients. A cross-sectional study was performed within a healthcare management organization by using individual data from 2 consecutive years (88,795 people). The dependent variable consisted of healthcare costs above the 95th percentile (P95), including all services provided by the organization and pharmaceutical consumption outside of the institution. The predictive variables were age, sex, morbidity-based on clinical risk groups (CRG)-and selected data from previous utilization (use of hospitalization, use of high-cost drugs in ambulatory care, pharmaceutical expenditure). A univariate descriptive analysis was performed. We constructed a logistic regression model with a 95% confidence level and analyzed sensitivity, specificity, positive predictive values (PPV), and the area under the ROC curve (AUC). Individuals incurring costs >P95 accumulated 44% of total healthcare costs and were concentrated in ACRG3 (aggregated CRG level 3) categories related to multiple chronic diseases. All variables were statistically significant except for sex. The model had a sensitivity of 48.4% (CI: 46.9%-49.8%), specificity of 97.2% (CI: 97.0%-97.3%), PPV of 46.5% (CI: 45.0%-47.9%), and an AUC of 0.897 (CI: 0.892 to 0.902). High consumption of healthcare resources is associated with complex chronic morbidity. A model based on age, morbidity, and prior utilization is able to predict high-cost risk and identify a target population requiring proactive care. Copyright © 2013 SESPAS. Published by Elsevier Espana. All rights reserved.

  2. Electrostatics of aquaporin and aquaglyceroporin channels correlates with their transport selectivity

    Science.gov (United States)

    Oliva, Romina; Calamita, Giuseppe; Thornton, Janet M.; Pellegrini-Calace, Marialuisa

    2010-01-01

    Aquaporins are homotetrameric channel proteins, which allow the diffusion of water and small solutes across biological membranes. According to their transport function, aquaporins can be divided into “orthodox aquaporins”, which allow the flux of water molecules only, and “aquaglyceroporins”, which facilitate the diffusion of glycerol and other small solutes in addition to water. The contribution of individual residues in the pore to the selectivity of orthodox aquaporins and aquaglyceroporins is not yet fully understood. To gain insights into aquaporin selectivity, we focused on the sequence variation and electrostatics of their channels. The continuum Poisson-Boltzmann electrostatic potential along the channel was calculated and compared for ten three-dimensional-structures which are representatives of different aquaporin subfamilies, and a panel of functionally characterized mutants, for which high-accuracy three-dimensional-models could be derived. Interestingly, specific electrostatic profiles associated with the main selectivity to water or glycerol could be identified. In particular: (i) orthodox aquaporins showed a distinctive electrostatic potential maximum at the periplasmic side of the channel around the aromatic/Arg (ar/R) constriction site; (ii) aquaporin-0 (AQP0), a mammalian aquaporin with considerably low water permeability, had an additional deep minimum at the cytoplasmic side; (iii) aquaglyceroporins showed a rather flat potential all along the channel; and (iv) the bifunctional protozoan PfAQP had an unusual all negative profile. Evaluation of electrostatics of the mutants, along with a thorough sequence analysis of the aquaporin pore-lining residues, illuminated the contribution of specific residues to the electrostatics of the channels and possibly to their selectivity. PMID:20147624

  3. Anion channels: master switches of stress responses.

    Science.gov (United States)

    Roelfsema, M Rob G; Hedrich, Rainer; Geiger, Dietmar

    2012-04-01

    During stress, plant cells activate anion channels and trigger the release of anions across the plasma membrane. Recently, two new gene families have been identified that encode major groups of anion channels. The SLAC/SLAH channels are characterized by slow voltage-dependent activation (S-type), whereas ALMT genes encode rapid-activating channels (R-type). Both S- and R-type channels are stimulated in guard cells by the stress hormone ABA, which leads to stomatal closure. Besides their role in ABA-dependent stomatal movement, anion channels are also activated by biotic stress factors such as microbe-associated molecular patterns (MAMPs). Given that anion channels occur throughout the plant kingdom, they are likely to serve a general function as master switches of stress responses. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Quantum privacy and Schur product channels

    Science.gov (United States)

    Levick, Jeremy; Kribs, David W.; Pereira, Rajesh

    2017-12-01

    We investigate the quantum privacy properties of an important class of quantum channels, by making use of a connection with Schur product matrix operations and associated correlation matrix structures. For channels implemented by mutually commuting unitaries, which cannot privatise qubits encoded directly into subspaces, we nevertheless identify private algebras and subsystems that can be privatised by the channels. We also obtain further results by combining our analysis with tools from the theory of quasi-orthogonal operator algebras and graph theory.

  5. Molecular analysis of a thylakoid K+channel

    International Nuclear Information System (INIS)

    1999-01-01

    The work undertaken sought to use a novel probe to identify and clone plant ion (K) channels. It was also proposed that in vitro biochemical studies of cation transport across purified preparations of thylakoid membrane be employed to characterize a putative K channel in this membrane system. Over the last several years, an enormous data base of partially-sequenced mRNAs and numerous genomes (including those of plants) has evolved and provides a powerful alternative to this brute-force approach to identify and clone cDNAs encoding physiologically important membrane proteins such as channels. The utility of searching genetic databases for relevant sequences, in addition to the difficulty of working with membrane proteins, led to changes in research focus during the granting period. During the course of the funding period, work was finished up which documented the presence of a K channel in the thylakoid membrane and demonstrated that K fluxes through this channel were required for optimal photosynthetic activity, likely due to the requirement for charge balancing of proton flux

  6. Molecular analysis of a thylakoid K+channel

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-09-10

    The work undertaken sought to use a novel probe to identify and clone plant ion (K) channels. It was also proposed that in vitro biochemical studies of cation transport across purified preparations of thylakoid membrane be employed to characterize a putative K channel in this membrane system. Over the last several years, an enormous data base of partially-sequenced mRNAs and numerous genomes (including those of plants) has evolved and provides a powerful alternative to this brute-force approach to identify and clone cDNAs encoding physiologically important membrane proteins such as channels. The utility of searching genetic databases for relevant sequences, in addition to the difficulty of working with membrane proteins, led to changes in research focus during the granting period. During the course of the funding period, work was finished up which documented the presence of a K channel in the thylakoid membrane and demonstrated that K fluxes through this channel were required for optimal photosynthetic activity, likely due to the requirement for charge balancing of proton flux.

  7. Voltage-gated calcium channels of Paramecium cilia.

    Science.gov (United States)

    Lodh, Sukanya; Yano, Junji; Valentine, Megan S; Van Houten, Judith L

    2016-10-01

    Paramecium cells swim by beating their cilia, and make turns by transiently reversing their power stroke. Reversal is caused by Ca 2+ entering the cilium through voltage-gated Ca 2+ (Ca V ) channels that are found exclusively in the cilia. As ciliary Ca 2+ levels return to normal, the cell pivots and swims forward in a new direction. Thus, the activation of the Ca V channels causes cells to make a turn in their swimming paths. For 45 years, the physiological characteristics of the Paramecium ciliary Ca V channels have been known, but the proteins were not identified until recently, when the P. tetraurelia ciliary membrane proteome was determined. Three Ca V α1 subunits that were identified among the proteins were cloned and confirmed to be expressed in the cilia. We demonstrate using RNA interference that these channels function as the ciliary Ca V channels that are responsible for the reversal of ciliary beating. Furthermore, we show that Pawn (pw) mutants of Paramecium that cannot swim backward for lack of Ca V channel activity do not express any of the three Ca V 1 channels in their ciliary membrane, until they are rescued from the mutant phenotype by expression of the wild-type PW gene. These results reinforce the correlation of the three Ca V channels with backward swimming through ciliary reversal. The PwB protein, found in endoplasmic reticulum fractions, co-immunoprecipitates with the Ca V 1c channel and perhaps functions in trafficking. The PwA protein does not appear to have an interaction with the channel proteins but affects their appearance in the cilia. © 2016. Published by The Company of Biologists Ltd.

  8. Cabbages and condoms: packaging and channels of distribution.

    Science.gov (United States)

    Potts, M

    1984-12-01

    Contraception is only rarely a therapy for disease. Usually, contraceptives help adults implement informed choices. Therefore, wider channels of distribution and promotion are possible and necessary than in the case of curative therapies. The more channels of distribution that are available for the same method of contraception, the higher the prevalence of use. Establishing new channels of distribution can be as important as developing new methods of contraception. Family planning is an important element in public health, and active promotion enhances the health of individuals and physicians. Other health professionals need to understand the role of non-medical skills and channels of contraceptive distribution.

  9. Elucidating distinct ion channel populations on the surface of hippocampal neurons via single-particle tracking recurrence analysis

    Science.gov (United States)

    Sikora, Grzegorz; Wyłomańska, Agnieszka; Gajda, Janusz; Solé, Laura; Akin, Elizabeth J.; Tamkun, Michael M.; Krapf, Diego

    2017-12-01

    Protein and lipid nanodomains are prevalent on the surface of mammalian cells. In particular, it has been recently recognized that ion channels assemble into surface nanoclusters in the soma of cultured neurons. However, the interactions of these molecules with surface nanodomains display a considerable degree of heterogeneity. Here, we investigate this heterogeneity and develop statistical tools based on the recurrence of individual trajectories to identify subpopulations within ion channels in the neuronal surface. We specifically study the dynamics of the K+ channel Kv1.4 and the Na+ channel Nav1.6 on the surface of cultured hippocampal neurons at the single-molecule level. We find that both these molecules are expressed in two different forms with distinct kinetics with regards to surface interactions, emphasizing the complex proteomic landscape of the neuronal surface. Further, the tools presented in this work provide new methods for the analysis of membrane nanodomains, transient confinement, and identification of populations within single-particle trajectories.

  10. Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

    Directory of Open Access Journals (Sweden)

    Xianwen He

    2017-01-01

    Full Text Available We consider the training design and channel estimation in the amplify-and-forward (AF diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI of second-hop link due to the multiaccess interference (MAI and cooperative data interference (CDI. To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.

  11. Channel Planform Dynamics Monitoring and Channel Stability Assessment in Two Sediment-Rich Rivers in Taiwan

    Directory of Open Access Journals (Sweden)

    Cheng-Wei Kuo

    2017-01-01

    Full Text Available Recurrent flood events induced by typhoons are powerful agents to modify channel morphology in Taiwan’s rivers. Frequent channel migrations reflect highly sensitive valley floors and increase the risk to infrastructure and residents along rivers. Therefore, monitoring channel planforms is essential for analyzing channel stability as well as improving river management. This study analyzed annual channel changes along two sediment-rich rivers, the Zhuoshui River and the Gaoping River, from 2008 to 2015 based on satellite images of FORMOSAT-2. Channel areas were digitized from mid-catchment to river mouth (~90 km. Channel stability for reaches was assessed through analyzing the changes of river indices including braid index, active channel width, and channel activity. In general, the valley width plays a key role in braided degree, active channel width, and channel activity. These indices increase as the valley width expands whereas the braid index decreases slightly close to the river mouth due to the change of river types. This downstream pattern in the Zhuoshui River was interrupted by hydraulic construction which resulted in limited changes downstream from the weir, due to the lack of water and sediment supply. A 200-year flood, Typhoon Morakot in 2009, induced significant changes in the two rivers. The highly active landscape in Taiwan results in very sensitive channels compared to other regions. An integrated Sensitivity Index was proposed for identifying unstable reaches, which could be a useful reference for river authorities when making priorities in river regulation strategy. This study shows that satellite image monitoring coupled with river indices analysis could be an effective tool to evaluate spatial and temporal changes in channel stability in highly dynamic river systems.

  12. Regional bankfull-channel dimensions of non-urban wadeable streams in Indiana

    Science.gov (United States)

    Robinson, Bret A.

    2013-01-01

    During floods, damage to properties and community infrastructure may result from inundation and the processes of erosion. The damages imparted by erosion are collectively termed the fluvial erosion hazard (FEH), and the Indiana Silver Jackets Multi-agency Hazard Mitigation Taskforce is supporting a program to build tools that will assist Indiana property owners and communities with FEH-mitigation efforts. As part of that program, regional channel-dimension relations are identified for non-urban wadeable streams in Indiana. With a site-selection process that targeted the three largest physiographic regions of the state, field work was completed to measure channel-dimension and channel-geometry characteristics across Indiana. In total, 82 sites were identified for data collection; 25 in the Northern Moraine and Lake region, 31 in the Central Till Plain region, and 26 in the Southern Hills and Lowlands region. Following well established methods, for each data-collection site, effort was applied to identify bankfull stage, determine bankfull-channel dimensions, and document channel-geometry characteristics that allowed for determinations of channel classification. In this report, regional bankfull-channel dimension results are presented as a combination of plots and regression equations that identify the relations between drainage area and the bankfull-channel dimensions of width, mean depth, and cross-sectional area. This investigation found that the channel-dimension data support independent relations for each of the three physiographic regions noted above. Furthermore, these relations show that, for any given drainage area, northern Indiana channels have the smallest predicted dimensions, southern Indiana channels have the largest predicted dimensions, and central Indiana channels are intermediate in their predicted dimensions. When considering the suite of variables that influence bankfull-channel dimensions, it appears that contrasting runoff characteristics

  13. Whose Line Sound is it Anyway? Identifying the Vocalizer on Underwater Video by Localizing with a Hydrophone Array

    Directory of Open Access Journals (Sweden)

    Matthias Hoffmann-Kuhnt

    2016-11-01

    Full Text Available A new device that combined high-resolution (1080p wide-angle video and three channels of high-frequency acoustic recordings (at 500 kHz per channel in a portable underwater housing was designed and tested with wild bottlenose and spotted dolphins in the Bahamas. It consisted of three hydrophones, a GoPro camera, a small Fit PC, a set of custom preamplifiers and a high-frequency data acquisition board. Recordings were obtained to identify individual vocalizing animals through time-delay-of-arrival localizing in post-processing. The calculated source positions were then overlaid onto the video – providing the ability to identify the vocalizing animal on the recorded video. The new tool allowed for much clearer analysis of the acoustic behavior of cetaceans than was possible before.

  14. Surface dynamics of voltage-gated ion channels

    Science.gov (United States)

    Heine, Martin; Ciuraszkiewicz, Anna; Voigt, Andreas; Heck, Jennifer; Bikbaev, Arthur

    2016-01-01

    ABSTRACT Neurons encode information in fast changes of the membrane potential, and thus electrical membrane properties are critically important for the integration and processing of synaptic inputs by a neuron. These electrical properties are largely determined by ion channels embedded in the membrane. The distribution of most ion channels in the membrane is not spatially uniform: they undergo activity-driven changes in the range of minutes to days. Even in the range of milliseconds, the composition and topology of ion channels are not static but engage in highly dynamic processes including stochastic or activity-dependent transient association of the pore-forming and auxiliary subunits, lateral diffusion, as well as clustering of different channels. In this review we briefly discuss the potential impact of mobile sodium, calcium and potassium ion channels and the functional significance of this for individual neurons and neuronal networks. PMID:26891382

  15. Identifying individual- and population-level characteristics that influence rates of risky alcohol consumption in regional communities.

    Science.gov (United States)

    Breen, Courtney; Shakeshaft, Anthony; Sanson-Fisher, Rob; D'Este, Catherine; Mattick, Richard P; Gilmour, Stuart

    2014-02-01

    To examine the extent to which individual- and community- level characteristics account for differences in risky alcohol consumption. A cross-sectional postal survey of 2,977 randomly selected individuals from 20 regional communities in NSW, Australia. Individuals drinking at harmful levels on the AUDIT and for risk of harm in the short term and long-term were identified. Multi-level modelling of the correlates of risky alcohol consumption at the individual and community level was conducted. There were differences between communities in alcohol consumption patterns. Being male, unmarried and reporting worse health were significant individual-level correlates for drinking at levels for risk of harm in the long term. The number of GPs (+) and police (-) were significant community characteristics. Being younger (≤25), unmarried, Australian born and with a larger income was associated with drinking at levels for risk of harm in the short term and harmful drinking on the AUDIT. The number of hotels and clubs was positively associated with drinking at levels for risk of harm in the short term. Rates of risky drinking vary significantly between communities and both individual and community characteristics are significantly associated with risky alcohol consumption. A combination of individual- and population-level interventions, tailored to the risk profile of individual communities, is most likely to be optimally effective. © 2014 The Authors. ANZJPH © 2014 Public Health Association of Australia.

  16. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

  17. Channelized Streams in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This draft dataset consists of all ditches or channelized pieces of stream that could be identified using three input datasets; namely the1:24,000 National...

  18. The risk of re-identification versus the need to identify individuals in rare disease research.

    Science.gov (United States)

    Hansson, Mats G; Lochmüller, Hanns; Riess, Olaf; Schaefer, Franz; Orth, Michael; Rubinstein, Yaffa; Molster, Caron; Dawkins, Hugh; Taruscio, Domenica; Posada, Manuel; Woods, Simon

    2016-11-01

    There is a growing concern in the ethics literature and among policy makers that de-identification or coding of personal data and biospecimens is not sufficient for protecting research subjects from privacy invasions and possible breaches of confidentiality due to the possibility of unauthorized re-identification. At the same time, there is a need in medical science to be able to identify individual patients. In particular for rare disease research there is a special and well-documented need for research collaboration so that data and biosamples from multiple independent studies can be shared across borders. In this article, we identify the needs and arguments related to de-identification and re-identification of patients and research subjects and suggest how the different needs may be balanced within a framework of using unique encrypted identifiers.

  19. A Risk Based Approach to Limit the Effects of Covert Channels for Internet Sensor Data Aggregators for Sensor Privacy

    Science.gov (United States)

    Viecco, Camilo H.; Camp, L. Jean

    Effective defense against Internet threats requires data on global real time network status. Internet sensor networks provide such real time network data. However, an organization that participates in a sensor network risks providing a covert channel to attackers if that organization’s sensor can be identified. While there is benefit for every party when any individual participates in such sensor deployments, there are perverse incentives against individual participation. As a result, Internet sensor networks currently provide limited data. Ensuring anonymity of individual sensors can decrease the risk of participating in a sensor network without limiting data provision.

  20. Molecular analysis of a thylakoid K+ channel

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-05-01

    The work undertaken during the prior granting period sought to use a novel probe to identify and clone plant ion (K) channels. It was also proposed that in vitro biochemical studies of cation transport across purified preparations of thylakoid membrane be employed to characterize a putative K channel in this membrane system. Over the last several years (including those of the previous grant period), an enormous data base of partially-sequenced mRNAs and numerous genomes (including those of plants) has evolved and provides a powerful alternative to this brute-force approach to identify and clone cDNAs ending physiologically important membrane proteins such as channels. The utility of searching genetic databases for relevant sequences, in addition to the difficulty of working with membrane proteins, led to changes in research focus during the prior granting period, and has resulted in the identification of a new class of plant ion channels, which will be the focus of research during the proposed new granting period.

  1. A Novel KCNJ2 Mutation Identified in an Autistic Proband Affects the Single Channel Properties of Kir2.1

    Directory of Open Access Journals (Sweden)

    Anna Binda

    2018-03-01

    Full Text Available Inwardly rectifying potassium channels (Kir have been historically associated to several cardiovascular disorders. In particular, loss-of-function mutations in the Kir2.1 channel have been reported in cases affected by Andersen-Tawil syndrome while gain-of-function mutations in the same channel cause the short QT3 syndrome. Recently, a missense mutation in Kir2.1, as well as mutations in the Kir4.1, were reported to be involved in autism spectrum disorders (ASDs suggesting a role of potassium channels in these diseases and introducing the idea of the existence of K+ channel ASDs. Here, we report the identification in an Italian affected family of a novel missense mutation (p.Phe58Ser in the KCNJ2 gene detected in heterozygosity in a proband affected by autism and borderline for short QT syndrome type 3. The mutation is located in the N-terminal region of the gene coding for the Kir2.1 channel and in particular in a very conserved domain. In vitro assays demonstrated that this mutation results in an increase of the channel conductance and in its open probability. This gain-of-function of the protein is consistent with the autistic phenotype, which is normally associated to an altered neuronal excitability.

  2. Single-channel in-ear-EEG detects the focus of auditory attention to concurrent tone streams and mixed speech

    Science.gov (United States)

    Fiedler, Lorenz; Wöstmann, Malte; Graversen, Carina; Brandmeyer, Alex; Lunner, Thomas; Obleser, Jonas

    2017-06-01

    Objective. Conventional, multi-channel scalp electroencephalography (EEG) allows the identification of the attended speaker in concurrent-listening (‘cocktail party’) scenarios. This implies that EEG might provide valuable information to complement hearing aids with some form of EEG and to install a level of neuro-feedback. Approach. To investigate whether a listener’s attentional focus can be detected from single-channel hearing-aid-compatible EEG configurations, we recorded EEG from three electrodes inside the ear canal (‘in-Ear-EEG’) and additionally from 64 electrodes on the scalp. In two different, concurrent listening tasks, participants (n  =  7) were fitted with individualized in-Ear-EEG pieces and were either asked to attend to one of two dichotically-presented, concurrent tone streams or to one of two diotically-presented, concurrent audiobooks. A forward encoding model was trained to predict the EEG response at single EEG channels. Main results. Each individual participants’ attentional focus could be detected from single-channel EEG response recorded from short-distance configurations consisting only of a single in-Ear-EEG electrode and an adjacent scalp-EEG electrode. The differences in neural responses to attended and ignored stimuli were consistent in morphology (i.e. polarity and latency of components) across subjects. Significance. In sum, our findings show that the EEG response from a single-channel, hearing-aid-compatible configuration provides valuable information to identify a listener’s focus of attention.

  3. Tourism distribution channels

    OpenAIRE

    Camilleri, Mark Anthony

    2017-01-01

    The distribution channels link the customers with the businesses. For many years, the tourism businesses may have distributed their products and services through intermediaries. However, the latest advances in technology have brought significant changes in this regard. More individuals and corporate customers are increasingly benefiting of ubiquitous technologies, including digital media. The development of mobile devices and their applications, are offering a wide range of possibilities to t...

  4. Applying alpha-channeling to mirror machines

    Energy Technology Data Exchange (ETDEWEB)

    Zhmoginov, A. I.; Fisch, N. J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States)

    2012-05-15

    The {alpha}-channeling effect entails the use of radio-frequency waves to expel and cool high-energetic {alpha} particles born in a fusion reactor; the device reactivity can then be increased even further by redirecting the extracted energy to fuel ions. Originally proposed for tokamaks, this technique has also been shown to benefit open-ended fusion devices. Here, the fundamental theory and practical aspects of {alpha} channeling in mirror machines are reviewed, including the influence of magnetic field inhomogeneity and the effect of a finite wave region on the {alpha}-channeling mechanism. For practical implementation of the {alpha}-channeling effect in mirror geometry, suitable contained weakly damped modes are identified. In addition, the parameter space of candidate waves for implementing the {alpha}-channeling effect can be significantly extended through the introduction of a suitable minority ion species that has the catalytic effect of moderating the transfer of power from the {alpha}-channeling wave to the fuel ions.

  5. Downregulation of Kv7.4 channel activity in primary and secondary hypertension

    DEFF Research Database (Denmark)

    Jepps, Thomas Andrew; Chadha, Preet S; Davis, Alison J

    2011-01-01

    Voltage-gated potassium (K(+)) channels encoded by KCNQ genes (Kv7 channels) have been identified in various rodent and human blood vessels as key regulators of vascular tone; however, nothing is known about the functional impact of these channels in vascular disease. We ascertained the effect of...... structurally different activators of Kv7.2 through Kv7.5 channels (BMS-204352, S-1, and retigabine) on blood vessels from normotensive and hypertensive animals.......Voltage-gated potassium (K(+)) channels encoded by KCNQ genes (Kv7 channels) have been identified in various rodent and human blood vessels as key regulators of vascular tone; however, nothing is known about the functional impact of these channels in vascular disease. We ascertained the effect of 3...

  6. An aberrant vascular channel in the petrous bone: persistent lateral capital vein?

    International Nuclear Information System (INIS)

    Hermans, Robert; Rensburg, Leon J. van

    2009-01-01

    An aberrant channel was identified on CT in the petrous bone in four patients presenting with unrelated otological symptoms. These channels occurred unilaterally in each case. In two patients, the channel was seen to run between the sigmoid sinus sulcus and the superior petrosal sinus sulcus; in one of these patients, a vascular structure was identified within this channel on MRI, connecting the sigmoid sinus and the superior petrosal sinus. In the two other patients, an aberrant channel was seen between the superior petrosal sinus sulcus and the posterior genu of the facial nerve canal. There were no symptoms that could be attributed to the presence of these channels. We postulate that these aberrant vascular channels correspond to a persistent embryological vein, the lateral capital vein. (orig.)

  7. An aberrant vascular channel in the petrous bone: persistent lateral capital vein?

    Energy Technology Data Exchange (ETDEWEB)

    Hermans, Robert [University Hospitals Leuven, Department of Radiology, Leuven (Belgium); Rensburg, Leon J. van [University of the Western Cape, Department of Radiology and Diagnostics, Tygerberg (South Africa)

    2009-12-15

    An aberrant channel was identified on CT in the petrous bone in four patients presenting with unrelated otological symptoms. These channels occurred unilaterally in each case. In two patients, the channel was seen to run between the sigmoid sinus sulcus and the superior petrosal sinus sulcus; in one of these patients, a vascular structure was identified within this channel on MRI, connecting the sigmoid sinus and the superior petrosal sinus. In the two other patients, an aberrant channel was seen between the superior petrosal sinus sulcus and the posterior genu of the facial nerve canal. There were no symptoms that could be attributed to the presence of these channels. We postulate that these aberrant vascular channels correspond to a persistent embryological vein, the lateral capital vein. (orig.)

  8. A proteomic strategy to identify novel serum biomarkers for liver cirrhosis and hepatocellular cancer in individuals with fatty liver disease

    Directory of Open Access Journals (Sweden)

    Stewart Stephen

    2009-08-01

    Full Text Available Abstract Background Non-alcoholic fatty liver disease (NAFLD has a prevalence of over 20% in Western societies. Affected individuals are at risk of developing both cirrhosis and hepatocellular cancer (HCC. Presently there is no cost effective population based means of identifying cirrhotic individuals and even if there were, our ability to perform HCC surveillance in the at risk group is inadequate. We have performed a pilot proteomic study to assess this as a strategy for serum biomarker detection. Methods 2D Gel electrophoresis was performed on immune depleted sera from 3 groups of patients, namely those with (1 pre-cirrhotic NAFLD (2 cirrhotic NAFLD and (3 cirrhotic NAFLD with co-existing HCC. Five spots differentiating at least one of these three groups were characterised by mass spectroscopy. An ELISA assay was optimised and a cross sectional study assessing one of these serum spots was performed on serum from 45 patients with steatohepatitis related cirrhosis and HCC and compared to 77 patients with histologically staged steatohepatitis. Results Four of the spots identified were apolipoprotein isoforms, the pattern of which was able to differentiate the three groups. The 5th spot, seen in the serum of cirrhotic individuals and more markedly in those with HCC, was identified as CD5 antigen like (CD5L. By ELISA assay, although CD5L was markedly elevated in a number of cirrhotic individuals with HCC, its overall ability to distinguish non-cancer from cancer individuals as determined by AUC ROC analysis was poor. However, serum CD5L was dramatically increased, independently of age, sex, and the presence of necroinflammation, in the serum of individuals with NAFLD cirrhosis relative to those with pre-cirrhotic disease. Conclusion This novel proteomic strategy has identified a number of candidate biomarkers which may have benefit in the surveillance and diagnosis of individuals with chronic liver disease and/or HCC.

  9. Ion channel profile of TRPM8 cold receptors reveals a novel role of TASK-3 potassium channels in thermosensation

    Science.gov (United States)

    Morenilla-Palao, Cruz; Luis, Enoch; Fernández-Peña, Carlos; Quintero, Eva; Weaver, Janelle L.; Bayliss, Douglas A.; Viana, Félix

    2017-01-01

    Summary Animals sense cold ambient temperatures through the activation of peripheral thermoreceptors that express TRPM8, a cold- and menthol-activated ion channel. These receptors can discriminate a very wide range of temperatures from innocuous to noxious. The molecular mechanism responsible for the variable sensitivity of individual cold receptors to temperature is unclear. To address this question, we performed a detailed ion channel expression analysis of cold sensitive neurons, combining BAC transgenesis with a molecular profiling approach in FACS purified TRPM8 neurons. We found that TASK-3 leak potassium channels are highly enriched in a subpopulation of these sensory neurons. The thermal threshold of TRPM8 cold neurons is decreased during TASK-3 blockade and in mice lacking TASK-3 and, most importantly, these mice display hypersensitivity to cold. Our results demonstrate a novel role of TASK-3 channels in thermosensation, showing that a channel-based combinatorial strategy in TRPM8 cold thermoreceptors leads to molecular specialization and functional diversity. PMID:25199828

  10. VKCDB: Voltage-gated potassium channel database

    Directory of Open Access Journals (Sweden)

    Gallin Warren J

    2004-01-01

    Full Text Available Abstract Background The family of voltage-gated potassium channels comprises a functionally diverse group of membrane proteins. They help maintain and regulate the potassium ion-based component of the membrane potential and are thus central to many critical physiological processes. VKCDB (Voltage-gated potassium [K] Channel DataBase is a database of structural and functional data on these channels. It is designed as a resource for research on the molecular basis of voltage-gated potassium channel function. Description Voltage-gated potassium channel sequences were identified by using BLASTP to search GENBANK and SWISSPROT. Annotations for all voltage-gated potassium channels were selectively parsed and integrated into VKCDB. Electrophysiological and pharmacological data for the channels were collected from published journal articles. Transmembrane domain predictions by TMHMM and PHD are included for each VKCDB entry. Multiple sequence alignments of conserved domains of channels of the four Kv families and the KCNQ family are also included. Currently VKCDB contains 346 channel entries. It can be browsed and searched using a set of functionally relevant categories. Protein sequences can also be searched using a local BLAST engine. Conclusions VKCDB is a resource for comparative studies of voltage-gated potassium channels. The methods used to construct VKCDB are general; they can be used to create specialized databases for other protein families. VKCDB is accessible at http://vkcdb.biology.ualberta.ca.

  11. Acoustic Imaging of a Turbidity Current Flowing along a Channel

    Science.gov (United States)

    Hughes Clarke, J. E.; Hiroji, A.; Cahill, L.; Fedele, J. J.

    2017-12-01

    As part of a 3 month sequence of repetitive surveys and ADCP monitoring, more than 30 turbidity currents have been identified modifying a lobe channel in 130 to 190m of water on the Squamish prodelta. For a 6 day period, daily surveys at low tide tried to capture the change resulting from a single flow. On the 8thof June three flows occurred within a half hour. Along channel multibeam images of the seabed and water column were obtained from a moving vessel immediately before, during and after the passage of the third flow. In this manner the spatial extent of the in-channel and overbank flow could be constrained. By following the flow, the spatial pattern of scattering from the flow upper surface could be examined over a 2 km length of the channel. Along channel bands of high scattering appear related to enhanced release of gas along the channel flanks. Notably, no signature of the underlying across-channel bedform modulations were evident, suggesting that the upper surface of the flow does not feel the influence of the channel floor. Overbank spillage of the flow could be detected by perturbation of a plankton scattering layer just above the seabed. Additionally, evidence of enhanced overbank deposition due to flow stripping on the outer corner of a bend was identified from backscatter changes. The specific seabed alteration due to this flow could be identified and compared with the cumulative change over three months in the channel and adjacent channel-lobe transition zone. As the flow passed under the ADCP, it had a peak velocity of over 2 m/s, a thickness of 4-5m and duration of 35 minutes. Based on the timing of the flow head when in view of the surface vessel, it was decelerating as it exited the mouth of the channel.

  12. A cement channel-detection technique using the pulsed-neutron log

    International Nuclear Information System (INIS)

    Myers, G.D.

    1991-01-01

    A channel-detection technique has been developed using boron solutions and pulsed-neutron logging (PNL) tools. This technique relies on the extremely high-neutron-absorption cross section that boron exhibits relative to other common elements, including chlorine. The PNL tool is used to detect movement of a boron solution in a log-inject-log procedure. The technique has identified channels in such difficult applications as logging through two strings of pipe and in highly deviated wellbores. Logging procedures are simple and cement channels can be readily identified. The boron solutions are relatively inexpensive, safe to handle, and nonradioactive. Additional PNL information for reservoir performance evaluation is collected simultaneously during channel-detection logging. This paper describes the theory, development, field application, and limitations of this channel-detection logging technique

  13. The Blurred Line between Form and Process: A Comparison of Stream Channel Classification Frameworks.

    Directory of Open Access Journals (Sweden)

    Alan Kasprak

    Full Text Available Stream classification provides a means to understand the diversity and distribution of channels and floodplains that occur across a landscape while identifying links between geomorphic form and process. Accordingly, stream classification is frequently employed as a watershed planning, management, and restoration tool. At the same time, there has been intense debate and criticism of particular frameworks, on the grounds that these frameworks classify stream reaches based largely on their physical form, rather than direct measurements of their component hydrogeomorphic processes. Despite this debate surrounding stream classifications, and their ongoing use in watershed management, direct comparisons of channel classification frameworks are rare. Here we implement four stream classification frameworks and explore the degree to which each make inferences about hydrogeomorphic process from channel form within the Middle Fork John Day Basin, a watershed of high conservation interest within the Columbia River Basin, U.S.A. We compare the results of the River Styles Framework, Natural Channel Classification, Rosgen Classification System, and a channel form-based statistical classification at 33 field-monitored sites. We found that the four frameworks consistently classified reach types into similar groups based on each reach or segment's dominant hydrogeomorphic elements. Where classified channel types diverged, differences could be attributed to the (a spatial scale of input data used, (b the requisite metrics and their order in completing a framework's decision tree and/or, (c whether the framework attempts to classify current or historic channel form. Divergence in framework agreement was also observed at reaches where channel planform was decoupled from valley setting. Overall, the relative agreement between frameworks indicates that criticism of individual classifications for their use of form in grouping stream channels may be overstated. These

  14. Molecular Epidemiology Identifies HIV Transmission Networks Associated With Younger Age and Heterosexual Exposure Among Korean Individuals

    OpenAIRE

    Chin, Bum Sik; Chaillon, Antoine; Mehta, Sanjay R.; Wertheim, Joel O.; Kim, Gayeon; Shin, Hyoung-Shik; Smith, Davey M.

    2016-01-01

    To evaluate if HIV transmission networks could be elucidated from data collected in a short time frame, 131 HIV-1 pol sequences were analyzed which were generated from treatment-naïve Korean individuals who were sequentially identified over 1 year. A transmission linkage was inferred when there was a genetic distance

  15. An evolutionarily conserved gene family encodes proton-selective ion channels.

    Science.gov (United States)

    Tu, Yu-Hsiang; Cooper, Alexander J; Teng, Bochuan; Chang, Rui B; Artiga, Daniel J; Turner, Heather N; Mulhall, Eric M; Ye, Wenlei; Smith, Andrew D; Liman, Emily R

    2018-03-02

    Ion channels form the basis for cellular electrical signaling. Despite the scores of genetically identified ion channels selective for other monatomic ions, only one type of proton-selective ion channel has been found in eukaryotic cells. By comparative transcriptome analysis of mouse taste receptor cells, we identified Otopetrin1 (OTOP1), a protein required for development of gravity-sensing otoconia in the vestibular system, as forming a proton-selective ion channel. We found that murine OTOP1 is enriched in acid-detecting taste receptor cells and is required for their zinc-sensitive proton conductance. Two related murine genes, Otop2 and Otop3 , and a Drosophila ortholog also encode proton channels. Evolutionary conservation of the gene family and its widespread tissue distribution suggest a broad role for proton channels in physiology and pathophysiology. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  16. Measuring individual work performance: Identifying and selecting indicators

    NARCIS (Netherlands)

    Koopmans, L.; Bernaards, C.M.; Hildebrandt, V.H.; de Vet, H.C.W.; van der Beek, A.J.

    2014-01-01

    BACKGROUND: Theoretically, individual work performance (IWP) can be divided into four dimensions: task performance, contextual performance, adaptive performance, and counterproductive work behavior. However, there is no consensus on the indicators used to measure these dimensions.

  17. Ca²⁺-dependent K⁺ channels in exocrine salivary glands.

    Science.gov (United States)

    Catalán, Marcelo A; Peña-Munzenmayer, Gaspar; Melvin, James E

    2014-06-01

    In the last 15 years, remarkable progress has been realized in identifying the genes that encode the ion-transporting proteins involved in exocrine gland function, including salivary glands. Among these proteins, Ca(2+)-dependent K(+) channels take part in key functions including membrane potential regulation, fluid movement and K(+) secretion in exocrine glands. Two K(+) channels have been identified in exocrine salivary glands: (1) a Ca(2+)-activated K(+) channel of intermediate single channel conductance encoded by the KCNN4 gene, and (2) a voltage- and Ca(2+)-dependent K(+) channel of large single channel conductance encoded by the KCNMA1 gene. This review focuses on the physiological roles of Ca(2+)-dependent K(+) channels in exocrine salivary glands. We also discuss interesting recent findings on the regulation of Ca(2+)-dependent K(+) channels by protein-protein interactions that may significantly impact exocrine gland physiology. Published by Elsevier Ltd.

  18. How well do the rosgen classification and associated "natural channel design" methods integrate and quantify fluvial processes and channel response?

    Science.gov (United States)

    Simon, A.; Doyle, M.; Kondolf, M.; Shields, F.D.; Rhoads, B.; Grant, G.; Fitzpatrick, F.; Juracek, K.; McPhillips, M.; MacBroom, J.

    2005-01-01

    Over the past 10 years the Rosgen classification system and its associated methods of "natural channel design" have become synonymous (to many without prior knowledge of the field) with the term "stream restoration" and the science of fluvial geomorphology. Since the mid 1990s, this classification approach has become widely, and perhaps dominantly adopted by governmental agencies, particularly those funding restoration projects. For example, in a request for proposals for the restoration of Trout Creek in Montana, the Natural Resources Conservation Service required "experience in the use and application of a stream classification system and its implementation." Similarly, classification systems have been used in evaluation guides for riparian areas and U.S. Forest Service management plans. Most notably, many highly trained geomorphologists and hydraulic engineers are often held suspect, or even thought incorrect, if their approach does not include reference to or application of a classification system. This, combined with the para-professional training provided by some involved in "natural channel design" empower individuals and groups with limited backgrounds in stream and watershed sciences to engineer wholesale re-patterning of stream reaches using 50-year old technology that was never intended for engineering design. At Level I, the Rosgen classification system consists of eight or nine major stream types, based on hydraulic-geometry relations and four other measures of channel shape to distinguish the dimensions of alluvial stream channels as a function of the bankfull stage. Six classes of the particle size of the boundary sediments are used to further sub-divide each of the major stream types, resulting in 48 or 54 stream types. Aside from the difficulty in identifying bankfull stage, particularly in incising channels, and the issue of sampling from two distinct populations (beds and banks) to classify the boundary sediments, the classification provides a

  19. Measuring individual work performance: identifying and selecting indicators

    NARCIS (Netherlands)

    Koopmans, L.; Bernaards, C.M.; Hildebrandt, V.H.; Vet, H.C de; Beek, A.J. van der

    2014-01-01

    BACKGROUND: Theoretically, individual work performance (IWP) can be divided into four dimensions: task performance, contextual performance, adaptive performance, and counterproductive work behavior. However, there is no consensus on the indicators used to measure these dimensions. OBJECTIVE: This

  20. Maturation, fertilisation and culture of bovine oocytes and embryos in an individually identifiable manner: a tool for studying oocyte developmental competence.

    Science.gov (United States)

    Matoba, Satoko; Fair, Trudee; Lonergan, Patrick

    2010-01-01

    The ability to successfully culture oocytes and embryos individually would facilitate the study of the relationship between follicle parameters and oocyte developmental competence, in order to identify markers of competent oocytes, as well as the ability to use small numbers of oocytes from an individual donor such as when ovum pick-up is carried out. Using a total of 3118 oocytes, the aim of the present study was to develop a system capable of supporting the development of immature bovine oocytes to the blastocyst stage in an individually identifiable manner. Initially, post-fertilisation embryo culture in the Well-of-the-Well (WOW) system, on the cell adhesive Cell-Tak or in polyester mesh was tested and shown to result in similar development to embryos cultured in standard group culture. The results demonstrate that it is possible to culture bovine oocytes to the blastocyst stage in an individually identifiable manner in all three culture systems with comparable success rates. This permits the localisation and identification of individual embryos throughout preimplantation development in vitro while retaining the developmental benefits of group culture. In terms of ease of preparation and use, culture in isolation within the strands of a polyester mesh is preferable.

  1. Three-dimensional (3-D) video systems: bi-channel or single-channel optics?

    Science.gov (United States)

    van Bergen, P; Kunert, W; Buess, G F

    1999-11-01

    This paper presents the results of a comparison between two different three-dimensional (3-D) video systems, one with single-channel optics, the other with bi-channel optics. The latter integrates two lens systems, each transferring one half of the stereoscopic image; the former uses only one lens system, similar to a two-dimensional (2-D) endoscope, which transfers the complete stereoscopic picture. In our training centre for minimally invasive surgery, surgeons were involved in basic and advanced laparoscopic courses using both a 2-D system and the two 3-D video systems. They completed analog scale questionnaires in order to record a subjective impression of the relative convenience of operating in 2-D and 3-D vision, and to identify perceived deficiencies in the 3-D system. As an objective test, different experimental tasks were developed, in order to measure performance times and to count pre-defined errors made while using the two 3-D video systems and the 2-D system. Using the bi-channel optical system, the surgeon has a heightened spatial perception, and can work faster and more safely than with a single-channel system. However, single-channel optics allow the use of an angulated endoscope, and the free rotation of the optics relative to the camera, which is necessary for some operative applications.

  2. On-line gas mixing and multi-channel distribution system

    International Nuclear Information System (INIS)

    Kalmani, S.D.; Mondal, N.K.; Satyanarayana, B.; Verma, P.; Joshi, Avinash

    2009-01-01

    In this presentation, we describe a mass-flow controller based on-line gas mixing unit with the multi-channel distribution system. We highlight different aspects such as requirement, design, calibration, control and operation of this system. This unit has the capability to mix up to four different input gases and distribute over 16 output channels. Output in individual channels is controlled accurately by using capillary-based system. At present, we are using this gas mixing unit for prototype of iron calorimeter (ICAL) detector of India-based Neutrino Observatory (INO).

  3. Sub-nanometre channels embedded in two-dimensional materials

    KAUST Repository

    Han, Yimo; Li, Ming-yang; Jung, Gang-Seob; Marsalis, Mark A.; Qin, Zhao; Buehler, Markus J.; Li, Lain-Jong; Muller, David A.

    2017-01-01

    with the embedding 2D matrix. Periodic dislocation arrays produce 2D superlattices of coherent MoS2 1D channels in WSe2. Using molecular dynamics simulations, we have identified other combinations of 2D materials where 1D channels can also be formed. The electronic

  4. A note on name individuation and identifying descriptions

    African Journals Online (AJOL)

    Kate H

    used to refer to either the famous philosopher or to the shipping magnate. ..... chain that produced the use of the name is a list containing the generic name and the ... arcane issues concerning currency individuation, object to my claim that I ...

  5. Excitation of fluorescent nanoparticles by channel plasmon polaritons propagating in V-grooves

    DEFF Research Database (Denmark)

    Cuesta, Irene Fernandez; Nielsen, Rasmus Bundgaard; Boltasseva, Alexandra

    2009-01-01

    Recently, it has been proven that light can be squeezed into metallic channels with subwavelength lateral dimensions. Here, we present the study of the propagation of channel plasmon polaritons confined in gold V-grooves, filled with fluorescent particles. In this way, channel plasmon polaritons......-diameter beads, we show the possibility of individual excitation, what may have applications to develop very sensitive biosensors....

  6. Optimizing multi-channel use in digital marketing campaigns

    OpenAIRE

    Lemos, André Miguel Fonseca

    2015-01-01

    Digital marketing has been gaining importance in the last years. It has become an easier, faster and more accountable way to reach customers than traditional, offline marketing, leading to more effective results and lower campaign costs. In digital marketing, the need to constantly reach large audiences is met by integrating online communication channels, as this increases customer touch points and ad exposures. It becomes thus important to know which channels perform better, individually or ...

  7. Computational Investigations in Rectangular Convergent and Divergent Ribbed Channels

    Science.gov (United States)

    Sivakumar, Karthikeyan; Kulasekharan, N.; Natarajan, E.

    2018-05-01

    Computational investigations on the rib turbulated flow inside a convergent and divergent rectangular channel with square ribs of different rib heights and different Reynolds numbers (Re=20,000, 40,000 and 60,000). The ribs were arranged in a staggered fashion between the upper and lower surfaces of the test section. Computational investigations are carried out using computational fluid dynamic software ANSYS Fluent 14.0. Suitable solver settings like turbulence models were identified from the literature and the boundary conditions for the simulations on a solution of independent grid. Computations were carried out for both convergent and divergent channels with 0 (smooth duct), 1.5, 3, 6, 9 and 12 mm rib heights, to identify the ribbed channel with optimal performance, assessed using a thermo hydraulic performance parameter. The convergent and divergent rectangular channels show higher Nu values than the standard correlation values.

  8. AFM imaging reveals the tetrameric structure of the TRPC1 channel

    International Nuclear Information System (INIS)

    Barrera, Nelson P.; Shaifta, Yasin; McFadzean, Ian; Ward, Jeremy P.T.; Henderson, Robert M.; Edwardson, J. Michael

    2007-01-01

    We have determined the subunit stoichiometry of the transient receptor potential C1 (TRPC1) channel by imaging isolated channels using atomic force microscopy (AFM). A frequency distribution of the molecular volumes of individual channel particles had two peaks, at 170 and 720 nm 3 , corresponding with the expected sizes of TRPC1 monomers and tetramers, respectively. Complexes were formed between TRPC1 channels and antibodies against a V5 epitope tag present on each subunit. The frequency distribution of angles between pairs of bound antibodies had two peaks, at 88 o and 178 o . This result again indicates that the channel assembles as a tetramer

  9. Perception of 'Back-Channeling' Nonverbal Feedback in Musical Duo Improvisation.

    Science.gov (United States)

    Moran, Nikki; Hadley, Lauren V; Bader, Maria; Keller, Peter E

    2015-01-01

    In witnessing face-to-face conversation, observers perceive authentic communication according to the social contingency of nonverbal feedback cues ('back-channeling') by non-speaking interactors. The current study investigated the generality of this function by focusing on nonverbal communication in musical improvisation. A perceptual experiment was conducted to test whether observers can reliably identify genuine versus fake (mismatched) duos from musicians' nonverbal cues, and how this judgement is affected by observers' musical background and rhythm perception skill. Twenty-four musicians were recruited to perform duo improvisations, which included solo episodes, in two styles: standard jazz (where rhythm is based on a regular pulse) or free improvisation (where rhythm is non-pulsed). The improvisations were recorded using a motion capture system to generate 16 ten-second point-light displays (with audio) of the soloist and the silent non-soloing musician ('back-channeler'). Sixteen further displays were created by splicing soloists with back-channelers from different duos. Participants (N = 60) with various musical backgrounds were asked to rate the point-light displays as either real or fake. Results indicated that participants were sensitive to the real/fake distinction in the free improvisation condition independently of musical experience. Individual differences in rhythm perception skill did not account for performance in the free condition, but were positively correlated with accuracy in the standard jazz condition. These findings suggest that the perception of back-channeling in free improvisation is not dependent on music-specific skills but is a general ability. The findings invite further study of the links between interpersonal dynamics in conversation and musical interaction.

  10. Calibration and assessment of channel-specific biases in microarray data with extended dynamical range.

    Science.gov (United States)

    Bengtsson, Henrik; Jönsson, Göran; Vallon-Christersson, Johan

    2004-11-12

    Non-linearities in observed log-ratios of gene expressions, also known as intensity dependent log-ratios, can often be accounted for by global biases in the two channels being compared. Any step in a microarray process may introduce such offsets and in this article we study the biases introduced by the microarray scanner and the image analysis software. By scanning the same spotted oligonucleotide microarray at different photomultiplier tube (PMT) gains, we have identified a channel-specific bias present in two-channel microarray data. For the scanners analyzed it was in the range of 15-25 (out of 65,535). The observed bias was very stable between subsequent scans of the same array although the PMT gain was greatly adjusted. This indicates that the bias does not originate from a step preceding the scanner detector parts. The bias varies slightly between arrays. When comparing estimates based on data from the same array, but from different scanners, we have found that different scanners introduce different amounts of bias. So do various image analysis methods. We propose a scanning protocol and a constrained affine model that allows us to identify and estimate the bias in each channel. Backward transformation removes the bias and brings the channels to the same scale. The result is that systematic effects such as intensity dependent log-ratios are removed, but also that signal densities become much more similar. The average scan, which has a larger dynamical range and greater signal-to-noise ratio than individual scans, can then be obtained. The study shows that microarray scanners may introduce a significant bias in each channel. Such biases have to be calibrated for, otherwise systematic effects such as intensity dependent log-ratios will be observed. The proposed scanning protocol and calibration method is simple to use and is useful for evaluating scanner biases or for obtaining calibrated measurements with extended dynamical range and better precision. The

  11. Functional Properties of a Newly Identified C-terminal Splice Variant of Cav1.3 L-type Ca2+ Channels*

    Science.gov (United States)

    Bock, Gabriella; Gebhart, Mathias; Scharinger, Anja; Jangsangthong, Wanchana; Busquet, Perrine; Poggiani, Chiara; Sartori, Simone; Mangoni, Matteo E.; Sinnegger-Brauns, Martina J.; Herzig, Stefan; Striessnig, Jörg; Koschak, Alexandra

    2011-01-01

    An intramolecular interaction between a distal (DCRD) and a proximal regulatory domain (PCRD) within the C terminus of long Cav1.3 L-type Ca2+ channels (Cav1.3L) is a major determinant of their voltage- and Ca2+-dependent gating kinetics. Removal of these regulatory domains by alternative splicing generates Cav1.342A channels that activate at a more negative voltage range and exhibit more pronounced Ca2+-dependent inactivation. Here we describe the discovery of a novel short splice variant (Cav1.343S) that is expressed at high levels in the brain but not in the heart. It lacks the DCRD but, in contrast to Cav1.342A, still contains PCRD. When expressed together with α2δ1 and β3 subunits in tsA-201 cells, Cav1.343S also activated at more negative voltages like Cav1.342A but Ca2+-dependent inactivation was less pronounced. Single channel recordings revealed much higher channel open probabilities for both short splice variants as compared with Cav1.3L. The presence of the proximal C terminus in Cav1.343S channels preserved their modulation by distal C terminus-containing Cav1.3- and Cav1.2-derived C-terminal peptides. Removal of the C-terminal modulation by alternative splicing also induced a faster decay of Ca2+ influx during electrical activities mimicking trains of neuronal action potentials. Our findings extend the spectrum of functionally diverse Cav1.3 L-type channels produced by tissue-specific alternative splicing. This diversity may help to fine tune Ca2+ channel signaling and, in the case of short variants lacking a functional C-terminal modulation, prevent excessive Ca2+ accumulation during burst firing in neurons. This may be especially important in neurons that are affected by Ca2+-induced neurodegenerative processes. PMID:21998310

  12. Iron status of channel catfish Ictalurus punctatus affected by channel catfish anemia and response to parenteral iron

    Science.gov (United States)

    Originally reported in 1983, channel catfish anemia (CCA), also ‘white lip’ or ‘no blood,’ is a major idiopathic disease affecting commercial production in the Mississippi Delta region of the USA. Affected individuals are characterized by lethargy, anorexia, extreme pallor, and packed cell volumes o...

  13. Mechanosensitive Piezo Channels in the Gastrointestinal Tract.

    Science.gov (United States)

    Alcaino, C; Farrugia, G; Beyder, A

    2017-01-01

    Sensation of mechanical forces is critical for normal function of the gastrointestinal (GI) tract and abnormalities in mechanosensation are linked to GI pathologies. In the GI tract there are several mechanosensitive cell types-epithelial enterochromaffin cells, intrinsic and extrinsic enteric neurons, smooth muscle cells and interstitial cells of Cajal. These cells use mechanosensitive ion channels that respond to mechanical forces by altering transmembrane ionic currents in a process called mechanoelectrical coupling. Several mechanosensitive ionic conductances have been identified in the mechanosensory GI cells, ranging from mechanosensitive voltage-gated sodium and calcium channels to the mechanogated ion channels, such as the two-pore domain potassium channels K2P (TREK-1) and nonselective cation channels from the transient receptor potential family. The recently discovered Piezo channels are increasingly recognized as significant contributors to cellular mechanosensitivity. Piezo1 and Piezo2 are nonselective cationic ion channels that are directly activated by mechanical forces and have well-defined biophysical and pharmacologic properties. The role of Piezo channels in the GI epithelium is currently under investigation and their role in the smooth muscle syncytium and enteric neurons is still not known. In this review, we outline the current state of knowledge on mechanosensitive ion channels in the GI tract, with a focus on the known and potential functions of the Piezo channels. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Determining the optimal approach to identifying individuals with chronic obstructive pulmonary disease: The DOC study.

    Science.gov (United States)

    Ronaldson, Sarah J; Dyson, Lisa; Clark, Laura; Hewitt, Catherine E; Torgerson, David J; Cooper, Brendan G; Kearney, Matt; Laughey, William; Raghunath, Raghu; Steele, Lisa; Rhodes, Rebecca; Adamson, Joy

    2018-06-01

    Early identification of chronic obstructive pulmonary disease (COPD) results in patients receiving appropriate management for their condition at an earlier stage in their disease. The determining the optimal approach to identifying individuals with chronic obstructive pulmonary disease (DOC) study was a case-finding study to enhance early identification of COPD in primary care, which evaluated the diagnostic accuracy of a series of simple lung function tests and symptom-based case-finding questionnaires. Current smokers aged 35 or more were invited to undertake a series of case-finding tools, which comprised lung function tests (specifically, spirometry, microspirometry, peak flow meter, and WheezoMeter) and several case-finding questionnaires. The effectiveness of these tests, individually or in combination, to identify small airways obstruction was evaluated against the gold standard of spirometry, with the quality of spirometry tests assessed by independent overreaders. The study was conducted with general practices in the Yorkshire and Humberside area, in the UK. Six hundred eighty-one individuals met the inclusion criteria, with 444 participants completing their study appointments. A total of 216 (49%) with good-quality spirometry readings were included in the analysis. The most effective case-finding tools were found to be the peak flow meter alone, the peak flow meter plus WheezoMeter, and microspirometry alone. In addition to the main analysis, where the severity of airflow obstruction was based on fixed ratios and percent of predicted values, sensitivity analyses were conducted by using lower limit of normal values. This research informs the choice of test for COPD identification; case-finding by use of the peak flow meter or microspirometer could be used routinely in primary care for suspected COPD patients. Only those testing positive to these tests would move on to full spirometry, thereby reducing unnecessary spirometric testing. © 2018 John Wiley

  15. Optical Communications Channel Combiner

    Science.gov (United States)

    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.

  16. MUSIC: An 8 channel readout ASIC for SiPM arrays

    Science.gov (United States)

    Gómez, Sergio; Gascón, David; Fernández, Gerard; Sanuy, Andreu; Mauricio, Joan; Graciani, Ricardo; Sanchez, David

    2016-04-01

    This paper presents an 8 channel ASIC for SiPM anode readout based on a novel low input impedance current conveyor (under patent1). This Multiple Use SiPM Integrated Circuit (MUSIC) has been designed to serve several purposes, including, for instance, the readout of SiPM arrays for some of the Cherenkov Telescope Array (CTA) cameras. The current division scheme at the very front end part of the circuit splits the input current into differently scaled copies which are connected to independent current mirrors. The circuit contains a tunable pole zero cancellation of the SiPM recovery time constant to deal with sensors from different manufacturers. Decay times up to 100 ns are supported covering most of the available SiPM devices in the market. MUSIC offers three main features: (1) differential output of the sum of the individual input channels; (2) 8 individual single ended analog outputs and; (3) 8 individual binary outputs. The digital outputs encode the amount of collected charge in the duration of the digital signal using a time over threshold technique. For each individual channel, the user must select the analog or digital output. Each functionality, the signal sum and the 8 A/D outputs, include a selectable dual-gain configuration. Moreover, the signal sum implements dual-gain output providing a 15 bit dynamic range. Full die simulation results of the MUSIC designed using AMS 0.35 µm SiGe technology are presented: total die size of 9 mm2, 500 MHz bandwidth for channel sum and 150 MHz bandwidth for A/D channels, low input impedance (≍32 Ω), single photon output pulse width at half maximum (FWHM) between 5 and 10 ns and with a power consumption of ≍ 30 mW/ch plus ≍ 200 mW for the 8 ch sum. Encapsulated prototype samples of the MUSIC are expected by March 2016.

  17. A novel potassium channel in photosynthetic cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Manuela Zanetti

    Full Text Available Elucidation of the structure-function relationship of a small number of prokaryotic ion channels characterized so far greatly contributed to our knowledge on basic mechanisms of ion conduction. We identified a new potassium channel (SynK in the genome of the cyanobacterium Synechocystis sp. PCC6803, a photosynthetic model organism. SynK, when expressed in a K(+-uptake-system deficient E. coli strain, was able to recover growth of these organisms. The protein functions as a potassium selective ion channel when expressed in Chinese hamster ovary cells. The location of SynK in cyanobacteria in both thylakoid and plasmamembranes was revealed by immunogold electron microscopy and Western blotting of isolated membrane fractions. SynK seems to be conserved during evolution, giving rise to a TPK (two-pore K(+ channel family member which is shown here to be located in the thylakoid membrane of Arabidopsis. Our work characterizes a novel cyanobacterial potassium channel and indicates the molecular nature of the first higher plant thylakoid cation channel, opening the way to functional studies.

  18. On the invariance of EEG-based signatures of individuality with application in biometric identification.

    Science.gov (United States)

    Yunqi Wang; Najafizadeh, Laleh

    2016-08-01

    One of the main challenges in EEG-based biometric systems is to extract reliable signatures of individuality from recorded EEG data that are also invariant against time. In this paper, we investigate the invariability of features that are extracted based on the spatial distribution of the spectral power of EEG data corresponding to 2-second eyes-closed resting-state (ECRS) recording, in different scenarios. Eyes-closed resting-state EEG signals in 4 healthy adults are recorded in two different sessions with an interval of at least one week between sessions. The performance in terms of correct recognition rate (CRR) is examined when the training and testing datasets are chosen from the same recording session, and when the training and testing datasets are chosen from different sessions. It is shown that an CRR of 92% can be achieved based on the proposed features when the training and testing datasets are taken from different sessions. To reduce the number of recording channels, principal component analysis (PCA) is also employed to identify channels that carry the most discriminatory information across individuals. High CRR is obtained based on the data from channels mostly covering the occipital region. The results suggest that features based on the spatial distribution of the spectral power of the short-time (e.g. 2 seconds) ECRS recordings can have great potentials in EEG-based biometric identification systems.

  19. Functional properties of a newly identified C-terminal splice variant of Cav1.3 L-type Ca2+ channels.

    Science.gov (United States)

    Bock, Gabriella; Gebhart, Mathias; Scharinger, Anja; Jangsangthong, Wanchana; Busquet, Perrine; Poggiani, Chiara; Sartori, Simone; Mangoni, Matteo E; Sinnegger-Brauns, Martina J; Herzig, Stefan; Striessnig, Jörg; Koschak, Alexandra

    2011-12-09

    An intramolecular interaction between a distal (DCRD) and a proximal regulatory domain (PCRD) within the C terminus of long Ca(v)1.3 L-type Ca(2+) channels (Ca(v)1.3(L)) is a major determinant of their voltage- and Ca(2+)-dependent gating kinetics. Removal of these regulatory domains by alternative splicing generates Ca(v)1.3(42A) channels that activate at a more negative voltage range and exhibit more pronounced Ca(2+)-dependent inactivation. Here we describe the discovery of a novel short splice variant (Ca(v)1.3(43S)) that is expressed at high levels in the brain but not in the heart. It lacks the DCRD but, in contrast to Ca(v)1.3(42A), still contains PCRD. When expressed together with α2δ1 and β3 subunits in tsA-201 cells, Ca(v)1.3(43S) also activated at more negative voltages like Ca(v)1.3(42A) but Ca(2+)-dependent inactivation was less pronounced. Single channel recordings revealed much higher channel open probabilities for both short splice variants as compared with Ca(v)1.3(L). The presence of the proximal C terminus in Ca(v)1.3(43S) channels preserved their modulation by distal C terminus-containing Ca(v)1.3- and Ca(v)1.2-derived C-terminal peptides. Removal of the C-terminal modulation by alternative splicing also induced a faster decay of Ca(2+) influx during electrical activities mimicking trains of neuronal action potentials. Our findings extend the spectrum of functionally diverse Ca(v)1.3 L-type channels produced by tissue-specific alternative splicing. This diversity may help to fine tune Ca(2+) channel signaling and, in the case of short variants lacking a functional C-terminal modulation, prevent excessive Ca(2+) accumulation during burst firing in neurons. This may be especially important in neurons that are affected by Ca(2+)-induced neurodegenerative processes.

  20. Activation of TRPM7 channels by small molecules under physiological conditions.

    Science.gov (United States)

    Hofmann, T; Schäfer, S; Linseisen, M; Sytik, L; Gudermann, T; Chubanov, V

    2014-12-01

    Transient receptor potential cation channel, subfamily M, member 7 (TRPM7) is a cation channel covalently linked to a protein kinase domain. TRPM7 is ubiquitously expressed and regulates key cellular processes such as Mg(2+) homeostasis, motility, and proliferation. TRPM7 is involved in anoxic neuronal death, cardiac fibrosis, and tumor growth. The goal of this work was to identify small molecule activators of the TRPM7 channel and investigate their mechanism of action. We used an aequorin bioluminescence-based assay to screen for activators of the TRPM7 channel. Valid candidates were further characterized using patch clamp electrophysiology. We identified 20 drug-like compounds with various structural backbones that can activate the TRPM7 channel. Among them, the δ opioid antagonist naltriben was studied in greater detail. Naltriben's action was selective among the TRP channels tested. Naltriben activates TRPM7 currents without prior depletion of intracellular Mg(2+) even under conditions of low PIP2. Moreover, naltriben interfered with the effect of the TRPM7 inhibitor NS8593. Finally, our experiments with TRPM7 variants carrying mutations in the pore, TRP, and kinase domains indicate that the site of TRPM7 activation by this small-molecule ligand is most likely located in or near the TRP domain. In conclusion, we identified the first organic small-molecule activators of TRPM7 channels, thus providing new experimental tools to study TRPM7 function in native cellular environments.

  1. ASIC3 channels in multimodal sensory perception.

    Science.gov (United States)

    Li, Wei-Guang; Xu, Tian-Le

    2011-01-19

    Acid-sensing ion channels (ASICs), which are members of the sodium-selective cation channels belonging to the epithelial sodium channel/degenerin (ENaC/DEG) family, act as membrane-bound receptors for extracellular protons as well as nonproton ligands. At least five ASIC subunits have been identified in mammalian neurons, which form both homotrimeric and heterotrimeric channels. The highly proton sensitive ASIC3 channels are predominantly distributed in peripheral sensory neurons, correlating with their roles in multimodal sensory perception, including nociception, mechanosensation, and chemosensation. Different from other ASIC subunit composing ion channels, ASIC3 channels can mediate a sustained window current in response to mild extracellular acidosis (pH 7.3-6.7), which often occurs accompanied by many sensory stimuli. Furthermore, recent evidence indicates that the sustained component of ASIC3 currents can be enhanced by nonproton ligands including the endogenous metabolite agmatine. In this review, we first summarize the growing body of evidence for the involvement of ASIC3 channels in multimodal sensory perception and then discuss the potential mechanisms underlying ASIC3 activation and mediation of sensory perception, with a special emphasis on its role in nociception. We conclude that ASIC3 activation and modulation by diverse sensory stimuli represent a new avenue for understanding the role of ASIC3 channels in sensory perception. Furthermore, the emerging implications of ASIC3 channels in multiple sensory dysfunctions including nociception allow the development of new pharmacotherapy.

  2. Major Channels Involved In Neuropsychiatric Disorders And Therapeutic Perspectives

    Directory of Open Access Journals (Sweden)

    Paola eImbrici

    2013-05-01

    Full Text Available Voltage-gated ion channels are important mediators of physiological functions in the central nervous system. The cyclic activation of these channels influences neurotransmitter release, neuron excitability, gene transcription and plasticity, providing distinct brain areas with unique physiological and pharmacological response. A growing body of data has implicated ion channels in the susceptibility or pathogenesis of psychiatric diseases. Indeed, population studies support the association of polymorphisms in calcium and potassium channels with the genetic risk for bipolar disorders or schizophrenia. Moreover, point mutations in calcium, sodium and potassium channel genes have been identified in some childhood developmental disorders. Finally, antibodies against potassium channel complexes occur in a series of autoimmune psychiatric diseases. Here we report recent studies assessing the role of calcium, sodium and potassium channels in bipolar disorder, schizophrenia and autism spectrum disorders, and briefly summarize promising pharmacological strategies targeted on ion channels for the therapy of mental illness and related genetic tests.

  3. Kv7 channels can function without constitutive calmodulin tethering.

    Directory of Open Access Journals (Sweden)

    Juan Camilo Gómez-Posada

    Full Text Available M-channels are voltage-gated potassium channels composed of Kv7.2-7.5 subunits that serve as important regulators of neuronal excitability. Calmodulin binding is required for Kv7 channel function and mutations in Kv7.2 that disrupt calmodulin binding cause Benign Familial Neonatal Convulsions (BFNC, a dominantly inherited human epilepsy. On the basis that Kv7.2 mutants deficient in calmodulin binding are not functional, calmodulin has been defined as an auxiliary subunit of Kv7 channels. However, we have identified a presumably phosphomimetic mutation S511D that permits calmodulin-independent function. Thus, our data reveal that constitutive tethering of calmodulin is not required for Kv7 channel function.

  4. Multicarrier chaotic communications in multipath fading channels without channel estimation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shilian, E-mail: wangsl@nudt.edu.cn; Zhang, Zhili [College of Electrical Science and Engineering, National University of Defense Technology, Changsha, 410073, P R China (China)

    2015-01-15

    A multi-carrier chaotic shift keying(MC-CSK) communication scheme with low probability of interception(LPI) is proposed in this article. We apply chaotic spreading sequences in the frequency domain, mapping a different chip of a chaotic sequence to an individual orthogonal frequency division multiplexing(OFDM) subcarrier. In each block size of $M$ OFDM symbols, we use one pilot OFDM symbol inserted time-spaced in all-frequency to transmit the reference chaotic signal and use the other M-1 OFDM symbols to transmit the information-bearing signals each spreaded by the reference chaotic signal. At the receiver, we construct a differential detector after DFT and recover the information bits from the correlations between the pilot OFDM symbol and the other M-1 OFDM symbols in each block size of M. Performance analysis and computer simulations show that the MC-CSK outperforms differential chaos shift keying(DCSK) in AWGN channels with high bandwidth efficiency for the block size of M=2 and that the MC-CSK exploits effectively the frequent diversity of the multipath channel.

  5. Multicarrier chaotic communications in multipath fading channels without channel estimation

    Directory of Open Access Journals (Sweden)

    Shilian Wang

    2015-01-01

    Full Text Available A multi-carrier chaotic shift keying(MC-CSK communication scheme with low probability of interception(LPI is proposed in this article. We apply chaotic spreading sequences in the frequency domain, mapping a different chip of a chaotic sequence to an individual orthogonal frequency division multiplexing(OFDM subcarrier. In each block size of $M$ OFDM symbols, we use one pilot OFDM symbol inserted time-spaced in all-frequency to transmit the reference chaotic signal and use the other M-1 OFDM symbols to transmit the information-bearing signals each spreaded by the reference chaotic signal. At the receiver, we construct a differential detector after DFT and recover the information bits from the correlations between the pilot OFDM symbol and the other M-1 OFDM symbols in each block size of M. Performance analysis and computer simulations show that the MC-CSK outperforms differential chaos shift keying(DCSK in AWGN channels with high bandwidth efficiency for the block size of M=2 and that the MC-CSK exploits effectively the frequent diversity of the multipath channel.

  6. Waves for Alpha-Channeling in Mirror Machines

    International Nuclear Information System (INIS)

    Zhmoginov, A.I.; Fisch, N.J.

    2009-01-01

    Alpha-channeling can, in principle, be implemented in mirror machines via exciting weaklydamped modes in the ion cyclotron frequency range with perpendicular wavelengths smaller than the alpha particle gyroradius. Assuming quasi-longitudinal or quasi-transverse wave propagation, we search systematically for suitable modes in mirror plasmas. Considering two device designs, a proof-of-principle facility and a fusion rector prototype, we in fact identify candidate modes suitable for alpha-channeling.

  7. Decision making by superimposing information from parallel cognitive channels

    Science.gov (United States)

    Aityan, Sergey K.

    1993-08-01

    A theory of decision making with perception through parallel information channels is presented. Decision making is considered a parallel competitive process. Every channel can provide confirmation or rejection of a decision concept. Different channels provide different impact on the specific concepts caused by the goals and individual cognitive features. All concepts are divided into semantic clusters due to the goals and the system defaults. The clusters can be alternative or complimentary. The 'winner-take-all' concept nodes firing takes place within the alternative cluster. Concepts can be independently activated in the complimentary cluster. A cognitive channel affects a decision concept by sending an activating or inhibitory signal. The complimentary clusters serve for building up complex concepts by superimposing activation received from various channels. The decision making is provided by the alternative clusters. Every active concept in the alternative cluster tends to suppress the competitive concepts in the cluster by sending inhibitory signals to the other nodes of the cluster. The model accounts for a time delay in signal transmission between the nodes and explains decreasing of the reaction time if information is confirmed by different channels and increasing of the reaction time if deceiving information received from the channels.

  8. Perception of 'Back-Channeling' Nonverbal Feedback in Musical Duo Improvisation.

    Directory of Open Access Journals (Sweden)

    Nikki Moran

    Full Text Available In witnessing face-to-face conversation, observers perceive authentic communication according to the social contingency of nonverbal feedback cues ('back-channeling' by non-speaking interactors. The current study investigated the generality of this function by focusing on nonverbal communication in musical improvisation. A perceptual experiment was conducted to test whether observers can reliably identify genuine versus fake (mismatched duos from musicians' nonverbal cues, and how this judgement is affected by observers' musical background and rhythm perception skill. Twenty-four musicians were recruited to perform duo improvisations, which included solo episodes, in two styles: standard jazz (where rhythm is based on a regular pulse or free improvisation (where rhythm is non-pulsed. The improvisations were recorded using a motion capture system to generate 16 ten-second point-light displays (with audio of the soloist and the silent non-soloing musician ('back-channeler'. Sixteen further displays were created by splicing soloists with back-channelers from different duos. Participants (N = 60 with various musical backgrounds were asked to rate the point-light displays as either real or fake. Results indicated that participants were sensitive to the real/fake distinction in the free improvisation condition independently of musical experience. Individual differences in rhythm perception skill did not account for performance in the free condition, but were positively correlated with accuracy in the standard jazz condition. These findings suggest that the perception of back-channeling in free improvisation is not dependent on music-specific skills but is a general ability. The findings invite further study of the links between interpersonal dynamics in conversation and musical interaction.

  9. Increasing support for contraception as HIV prevention: stakeholder mapping to identify influential individuals and their perceptions.

    Directory of Open Access Journals (Sweden)

    Tricia Petruney

    Full Text Available BACKGROUND: Voluntary contraceptive use by HIV-positive women currently prevents more HIV-positive births, at a lower cost, than anti-retroviral drug (ARV regimens. Despite this evidence, most prevention of mother-to-child transmission (PMTCT programs focus solely on providing ARV prophylaxis to pregnant women and rarely include the prevention of unintended pregnancies among HIV-positive women. METHODOLOGY/PRINCIPAL FINDINGS: To strengthen support for family planning as HIV prevention, we systematically identified key individuals in the field of international HIV/AIDS-those who could potentially influence the issue-and sought to determine their perceptions of barriers to and facilitators for implementing this PMTCT strategy. We used a criteria-based approach to determine which HIV/AIDS stakeholders have the most significant impact on HIV/AIDS research, programs, funding and policy and stratified purposive sampling to conduct interviews with a subset of these individuals. The interview findings pointed to obstacles to strengthening linkages between family planning and HIV/AIDS, including the need for: resources to integrate family planning and HIV services, infrastructure or capacity to provide integrated services at the facility level, national leadership and coordination, and targeted advocacy to key decision-makers. CONCLUSIONS/SIGNIFICANCE: The individuals we identified as having regional or international influence in the field of HIV/AIDS have the ability to leverage an increasingly conducive funding environment and a growing evidence base to address the policy, programmatic and operational challenges to integrating family planning with HIV/AIDS. Fostering greater support for implementing contraception for HIV prevention will require the dedication, collaboration and coordination of many such actors. Our findings can inform a targeted advocacy campaign.

  10. Superimposed Training-Based Channel Estimation for MIMO Relay Networks

    Directory of Open Access Journals (Sweden)

    Xiaoyan Xu

    2012-01-01

    Full Text Available We introduce the superimposed training strategy into the multiple-input multiple-output (MIMO amplify-and-forward (AF one-way relay network (OWRN to perform the individual channel estimation at the destination. Through the superposition of a group of additional training vectors at the relay subject to power allocation, the separated estimates of the source-relay and relay-destination channels can be obtained directly at the destination, and the accordance with the two-hop AF strategy can be guaranteed at the same time. The closed-form Bayesian Cramér-Rao lower bound (CRLB is derived for the estimation of two sets of flat-fading MIMO channel under random channel parameters and further exploited to design the optimal training vectors. A specific suboptimal channel estimation algorithm is applied in the MIMO AF OWRN using the optimal training sequences, and the normalized mean square error performance for the estimation is provided to verify the Bayesian CRLB results.

  11. Ion channels in the central regulation of energy and glucose homeostasis

    OpenAIRE

    Sohn, Jong-Woo

    2013-01-01

    Ion channels are critical regulators of neuronal excitability and synaptic function in the brain. Recent evidence suggests that ion channels expressed by neurons within the brain are responsible for regulating energy and glucose homeostasis. In addition, the central effects of neurotransmitters and hormones are at least in part achieved by modifications of ion channel activity. This review focuses on ion channels and their neuronal functions followed by a discussion of the identified roles fo...

  12. Evaluation of portable near infrared spectrophotometer to stage maturity in channel catfish

    Science.gov (United States)

    Gonadal maturity of channel catfish varies within the same cohort of fish. Female channel catfish with superior maturity need to be identified and staged for higher success to induce spawn wit ovulating hormones to produce channel x blue hybrid catfish fry in hatcheries. Maturation is not synchron...

  13. Channelling and electromagnetic radiation of channelling particles

    International Nuclear Information System (INIS)

    Kalashnikov, N.

    1983-01-01

    A brief description is presented of the channelling of charged particles between atoms in the crystal lattice. The specificities are discussed of the transverse motion of channelling particles as are the origin and properties of quasi-characteristic radiation of channelling particles which accompany transfers from one band of permissible energies of the transverse motion of channelling particles to the other. (B.S.)

  14. Calcium homeostasis modulator (CALHM) ion channels.

    Science.gov (United States)

    Ma, Zhongming; Tanis, Jessica E; Taruno, Akiyuki; Foskett, J Kevin

    2016-03-01

    Calcium homeostasis modulator 1 (CALHM1), formerly known as FAM26C, was recently identified as a physiologically important plasma membrane ion channel. CALHM1 and its Caenorhabditis elegans homolog, CLHM-1, are regulated by membrane voltage and extracellular Ca(2+) concentration ([Ca(2+)]o). In the presence of physiological [Ca(2+)]o (∼1.5 mM), CALHM1 and CLHM-1 are closed at resting membrane potentials but can be opened by strong depolarizations. Reducing [Ca(2+)]o increases channel open probability, enabling channel activation at negative membrane potentials. Together, voltage and Ca(2+) o allosterically regulate CALHM channel gating. Through convergent evolution, CALHM has structural features that are reminiscent of connexins and pannexins/innexins/LRRC8 (volume-regulated anion channel (VRAC)) gene families, including four transmembrane helices with cytoplasmic amino and carboxyl termini. A CALHM1 channel is a hexamer of CALHM1 monomers with a functional pore diameter of ∼14 Å. CALHM channels discriminate poorly among cations and anions, with signaling molecules including Ca(2+) and ATP able to permeate through its pore. CALHM1 is expressed in the brain where it plays an important role in cortical neuron excitability induced by low [Ca(2+)]o and in type II taste bud cells in the tongue that sense sweet, bitter, and umami tastes where it functions as an essential ATP release channel to mediate nonsynaptic neurotransmitter release. CLHM-1 is expressed in C. elegans sensory neurons and body wall muscles, and its genetic deletion causes locomotion defects. Thus, CALHM is a voltage- and Ca(2+) o-gated ion channel, permeable to large cations and anions, that plays important roles in physiology.

  15. Ion channels in the central regulation of energy and glucose homeostasis

    Directory of Open Access Journals (Sweden)

    Jong-Woo eSohn

    2013-05-01

    Full Text Available Ion channels are critical regulators of neuronal excitability and synaptic function in the brain. Recent evidence suggests that ion channels expressed by neurons within the brain are responsible for regulating energy and glucose homeostasis. In addition, the central effects of neurotransmitters and hormones are at least in part achieved by modifications of ion channel activity. This review focuses on ion channels and their neuronal functions followed by a discussion of the identified roles for specific ion channels in the central pathways regulating food intake, energy expenditure, and glucose balance.

  16. Identifying At-Risk Individuals for Insomnia Using the Ford Insomnia Response to Stress Test

    Science.gov (United States)

    Kalmbach, David A.; Pillai, Vivek; Arnedt, J. Todd; Drake, Christopher L.

    2016-01-01

    Study Objectives: A primary focus of the National Institute of Mental Health's current strategic plan is “predicting” who is at risk for disease. As such, the current investigation examined the utility of premorbid sleep reactivity in identifying a specific and manageable population at elevated risk for future insomnia. Methods: A community-based sample of adults (n = 2,892; 59.3% female; 47.9 ± 13.3 y old) with no lifetime history of insomnia or depression completed web-based surveys across three annual assessments. Participants reported parental history of insomnia, demographic characteristics, sleep reactivity on the Ford Insomnia in Response to Stress Test (FIRST), and insomnia symptoms. DSM-IV diagnostic criteria were used to determine insomnia classification. Results: Baseline FIRST scores were used to predict incident insomnia at 1-y follow-up. Two clinically meaningful FIRST cutoff values were identified: FIRST ≥ 16 (sensitivity 77%; specificity 50%; odds ratio [OR] = 2.88, P insomnia onset, even after controlling for stress exposure and demographic characteristics. Of the incident cases, insomniacs with highly reactive sleep systems reported longer sleep onset latencies (FIRST ≥ 16: 65 min; FIRST ≥ 18: 68 min) than participants with nonreactive insomnia (FIRST insomnia based on trait sleep reactivity. The FIRST accurately identifies a focused target population in which the psychobiological processes complicit in insomnia onset and progression can be better investigated, thus improving future preventive efforts. Citation: Kalmbach DA, Pillai V, Arnedt JT, Drake CL. Identifying at-risk individuals for insomnia using the ford insomnia response to stress test. SLEEP 2016;39(2):449–456. PMID:26446111

  17. Improving the service life and performance of CANDU fuel channels

    International Nuclear Information System (INIS)

    Causey, A.R.; Cheadle, B.A.; Coleman, C.E.; Price, E.G.

    1997-01-01

    The development objective for CANDU fuel channels is to produce a design that can operate for 40 years at 90% capacity. Steady progress toward this objective is being made. The factors that determine the life of the channel are reviewed and the processes necessary to achieve the objectives identified. Performance of future fuel channels will be enhanced by reduced operating costs, increased safety margins to postulated accident conditions, and reduced retubing costs compared to current channels. The approaches to these issues are discussed briefly in the paper. (author)

  18. Improving the service life and performance of CANDU fuel channels

    International Nuclear Information System (INIS)

    Coleman, C.E.; Cheadle, B.A.; Causey, A.R.; Doubt, G.L.; Fong, R.W.L.; Venkatapathi, S.

    1996-03-01

    The development objective for CANDU fuel channels is to produce a design that can operate for 40 years at 90% capacity. Steady progress toward this objective is being made. The factors that determine the life of a CANDU fuel channel are reviewed and the processes necessary to achieve the objectives are identified. Performance of future fuel channels will be enhanced by reduced operating costs and increased safety margins to postulated accident conditions compared with those for current channels. The approaches to these issues are discussed briefly in this report. (author)

  19. A thermal analysis computer programme package for the estimation of KANUPP coolant channel flows and outlet header temperature distribution

    International Nuclear Information System (INIS)

    Siddiqui, M.S.

    1992-06-01

    COFTAN is a computer code for actual estimation of flows and temperatures in the coolant channels of a pressure tube heavy water reactor. The code is being used for Candu type reactor with coolant flowing 208 channels. The simulation model first performs the detailed calculation of flux and power distribution based on two groups diffusion theory treatment on a three dimensional mesh and then channel powers, resulting from the summation of eleven bundle powers in each of the 208 channels, are employed to make actual estimation of coolant flows using channel powers and channel outlet temperature monitored by digital computers. The code by using the design flows in individual channels and applying a correction factor based on control room monitored flows in eight selected channels, can also provide a reserve computational tool of estimating individual channel outlet temperatures, thus providing an alternate arrangements for checking Rads performance. 42 figs. (Orig./A.B.)

  20. Liquid Water Transport in the Reactant Channels of Proton Exchange Membrane Fuel Cells

    Science.gov (United States)

    Banerjee, Rupak

    Water management has been identified as a critical issue in the development of PEM fuel cells for automotive applications. Water is present inside the PEM fuel cell in three phases, i.e. liquid phase, vapor phase and mist phase. Liquid water in the reactant channels causes flooding of the cell and blocks the transport of reactants to the reaction sites at the catalyst layer. Understanding the behavior of liquid water in the reactant channels would allow us to devise improved strategies for removing liquid water from the reactant channels. In situ fuel cell tests have been performed to identify and diagnose operating conditions which result in the flooding of the fuel cell. A relationship has been identified between the liquid water present in the reactant channels and the cell performance. A novel diagnostic technique has been established which utilizes the pressure drop multiplier in the reactant channels to predict the flooding of the cell or the drying-out of the membrane. An ex-situ study has been undertaken to quantify the liquid water present in the reactant channels. A new parameter, the Area Coverage Ratio (ACR), has been defined to identify the interfacial area of the reactant channel which is blocked for reactant transport by the presence of liquid water. A parametric study has been conducted to study the effect of changing temperature and the inlet relative humidity on the ACR. The ACR decreases with increase in current density as the gas flow rates increase, removing water more efficiently. With increase in temperature, the ACR decreases rapidly, such that by 60°C, there is no significant ACR to be reported. Inlet relative humidity of the gases does change the saturation of the gases in the channel, but did not show any significant effect on the ACR. Automotive powertrains, which is the target for this work, are continuously faced with transient changes. Water management under transient operating conditions is significantly more challenging and has not

  1. Spotting Cheetahs: Identifying Individuals by Their Footprints.

    Science.gov (United States)

    Jewell, Zoe C; Alibhai, Sky K; Weise, Florian; Munro, Stuart; Van Vuuren, Marlice; Van Vuuren, Rudie

    2016-05-01

    The cheetah (Acinonyx jubatus) is Africa's most endangered large felid and listed as Vulnerable with a declining population trend by the IUCN(1). It ranges widely over sub-Saharan Africa and in parts of the Middle East. Cheetah conservationists face two major challenges, conflict with landowners over the killing of domestic livestock, and concern over range contraction. Understanding of the latter remains particularly poor(2). Namibia is believed to support the largest number of cheetahs of any range country, around 30%, but estimates range from 2,905(3) to 13,520(4). The disparity is likely a result of the different techniques used in monitoring. Current techniques, including invasive tagging with VHF or satellite/GPS collars, can be costly and unreliable. The footprint identification technique(5) is a new tool accessible to both field scientists and also citizens with smartphones, who could potentially augment data collection. The footprint identification technique analyzes digital images of footprints captured according to a standardized protocol. Images are optimized and measured in data visualization software. Measurements of distances, angles, and areas of the footprint images are analyzed using a robust cross-validated pairwise discriminant analysis based on a customized model. The final output is in the form of a Ward's cluster dendrogram. A user-friendly graphic user interface (GUI) allows the user immediate access and clear interpretation of classification results. The footprint identification technique algorithms are species specific because each species has a unique anatomy. The technique runs in a data visualization software, using its own scripting language (jsl) that can be customized for the footprint anatomy of any species. An initial classification algorithm is built from a training database of footprints from that species, collected from individuals of known identity. An algorithm derived from a cheetah of known identity is then able to classify

  2. Spotting Cheetahs: Identifying Individuals by Their Footprints

    Science.gov (United States)

    Jewell, Zoe C.; Alibhai, Sky K.; Weise, Florian; Munro, Stuart; Van Vuuren, Marlice; Van Vuuren, Rudie

    2016-01-01

    The cheetah (Acinonyx jubatus) is Africa's most endangered large felid and listed as Vulnerable with a declining population trend by the IUCN1. It ranges widely over sub-Saharan Africa and in parts of the Middle East. Cheetah conservationists face two major challenges, conflict with landowners over the killing of domestic livestock, and concern over range contraction. Understanding of the latter remains particularly poor2. Namibia is believed to support the largest number of cheetahs of any range country, around 30%, but estimates range from 2,9053 to 13,5204. The disparity is likely a result of the different techniques used in monitoring. Current techniques, including invasive tagging with VHF or satellite/GPS collars, can be costly and unreliable. The footprint identification technique5 is a new tool accessible to both field scientists and also citizens with smartphones, who could potentially augment data collection. The footprint identification technique analyzes digital images of footprints captured according to a standardized protocol. Images are optimized and measured in data visualization software. Measurements of distances, angles, and areas of the footprint images are analyzed using a robust cross-validated pairwise discriminant analysis based on a customized model. The final output is in the form of a Ward's cluster dendrogram. A user-friendly graphic user interface (GUI) allows the user immediate access and clear interpretation of classification results. The footprint identification technique algorithms are species specific because each species has a unique anatomy. The technique runs in a data visualization software, using its own scripting language (jsl) that can be customized for the footprint anatomy of any species. An initial classification algorithm is built from a training database of footprints from that species, collected from individuals of known identity. An algorithm derived from a cheetah of known identity is then able to classify free

  3. Deep Learning for Distribution Channels' Management

    Directory of Open Access Journals (Sweden)

    Sabina-Cristiana NECULA

    2017-01-01

    Full Text Available This paper presents an experiment of using deep learning models for distribution channel management. We present an approach that combines self-organizing maps with artificial neural network with multiple hidden layers in order to identify the potential sales that might be addressed for channel distribution change/ management. Our study aims to highlight the evolution of techniques from simple features/learners to more complex learners and feature engineering or sampling techniques. This paper will allow researchers to choose best suited techniques and features to prepare their churn prediction models.

  4. Selective spider toxins reveal a role for Nav1.1 channel in mechanical pain

    Science.gov (United States)

    Osteen, Jeremiah D.; Herzig, Volker; Gilchrist, John; Emrick, Joshua J.; Zhang, Chuchu; Wang, Xidao; Castro, Joel; Garcia-Caraballo, Sonia; Grundy, Luke; Rychkov, Grigori Y.; Weyer, Andy D.; Dekan, Zoltan; Undheim, Eivind A. B.; Alewood, Paul; Stucky, Cheryl L.; Brierley, Stuart M.; Basbaum, Allan I.; Bosmans, Frank; King, Glenn F.; Julius, David

    2016-01-01

    Voltage-gated sodium (Nav) channels initiate action potentials in most neurons, including primary afferent nerve fibers of the pain pathway. Local anesthetics block pain through non-specific actions at all Nav channels, but the discovery of selective modulators would facilitate the analysis of individual subtypes and their contributions to chemical, mechanical, or thermal pain. Here, we identify and characterize spider toxins that selectively activate the Nav1.1 subtype, whose role in nociception and pain has not been explored. We exploit these probes to demonstrate that Nav1.1-expressing fibers are modality-specific nociceptors: their activation elicits robust pain behaviors without neurogenic inflammation and produces profound hypersensitivity to mechanical, but not thermal, stimuli. In the gut, high-threshold mechanosensitive fibers also express Nav1.1 and show enhanced toxin sensitivity in a model of irritable bowel syndrome. Altogether, these findings establish an unexpected role for Nav1.1 in regulating the excitability of sensory nerve fibers that underlie mechanical pain. PMID:27281198

  5. Identifying the Minimum Model Features to Replicate Historic Morphodynamics of a Juvenile Delta

    Science.gov (United States)

    Czapiga, M. J.; Parker, G.

    2017-12-01

    We introduce a quasi-2D morphodynamic delta model that improves on past models that require many simplifying assumptions, e.g. a single channel representative of a channel network, fixed channel width, and spatially uniform deposition. Our model is useful for studying long-term progradation rates of any generic micro-tidal delta system with specification of: characteristic grain size, input water and sediment discharges and basin morphology. In particular, we relax the assumption of a single, implicit channel sweeping across the delta topset in favor of an implicit channel network. This network, coupled with recent research on channel-forming Shields number, quantitative assessments of the lateral depositional length of sand (corresponding loosely to levees) and length between bifurcations create a spatial web of deposition within the receiving basin. The depositional web includes spatial boundaries for areas infilling with sands carried as bed material load, as well as those filling via passive deposition of washload mud. Our main goal is to identify the minimum features necessary to accurately model the morphodynamics of channel number, width, depth, and overall delta progradation rate in a juvenile delta. We use the Wax Lake Delta in Louisiana as a test site due to its rapid growth in the last 40 years. Field data including topset/island bathymetry, channel bathymetry, topset/island width, channel width, number of channels, and radial topset length are compiled from US Army Corps of Engineers data for 1989, 1998, and 2006. Additional data is extracted from a DEM from 2015. These data are used as benchmarks for the hindcast model runs. The morphology of Wax Lake Delta is also strongly affected by a pre-delta substrate that acts as a lower "bedrock" boundary. Therefore, we also include closures for a bedrock-alluvial transition and an excess shear rate-law incision model to estimate bedrock incision. The model's framework is generic, but inclusion of individual

  6. Optimal Channel Selection Based on Online Decision and Offline Learning in Multichannel Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mu Qiao

    2017-01-01

    Full Text Available We propose a channel selection strategy with hybrid architecture, which combines the centralized method and the distributed method to alleviate the overhead of access point and at the same time provide more flexibility in network deployment. By this architecture, we make use of game theory and reinforcement learning to fulfill the optimal channel selection under different communication scenarios. Particularly, when the network can satisfy the requirements of energy and computational costs, the online decision algorithm based on noncooperative game can help each individual sensor node immediately select the optimal channel. Alternatively, when the network cannot satisfy the requirements of energy and computational costs, the offline learning algorithm based on reinforcement learning can help each individual sensor node to learn from its experience and iteratively adjust its behavior toward the expected target. Extensive simulation results validate the effectiveness of our proposal and also prove that higher system throughput can be achieved by our channel selection strategy over the conventional off-policy channel selection approaches.

  7. Side-gated ultrathin-channel nanopore FET sensors

    International Nuclear Information System (INIS)

    Yanagi, Itaru; Haga, Takanobu; Ando, Masahiko; Yamamoto, Jiro; Mine, Toshiyuki; Ishida, Takeshi; Hatano, Toshiyuki; Akahori, Rena; Yokoi, Takahide; Anazawa, Takashi; Oura, Takeshi

    2016-01-01

    A side-gated, ultrathin-channel nanopore FET (SGNAFET) is proposed for fast and label-free DNA sequencing. The concept of the SGNAFET comprises the detection of changes in the channel current during DNA translocation through a nanopore and identifying the four types of nucleotides as a result of these changes. To achieve this goal, both p- and n-type SGNAFETs with a channel thicknesses of 2 or 4 nm were fabricated, and the stable transistor operation of both SGNAFETs in air, water, and a KCl buffer solution were confirmed. In addition, synchronized current changes were observed between the ionic current through the nanopore and the SGNAFET’s drain current during DNA translocation through the nanopore. (paper)

  8. Some properties of a channeling model of fracture flow

    International Nuclear Information System (INIS)

    Tsang, Y.W.; Tsang, C.F.; Neretnieks, I.

    1986-12-01

    The Gamma distribution and the log-normal distribution were used to describe the density distribution of the apertures within a channel. For every set of parameter values (correlation length, and the parameters of the distributions) 95 different statistically equivalent channels were generated. The aperture distribution along the channels are then used to determine the total channel volume, the hydraulic conductivity and the flow rate and residence time for a given gradient. The volumes of the channels were found to vary little whereas the hydraulic conductivity, which is primarily determined by the smallest aperture along the channels, varies considerably. For a wide density distribution the hydraulic conductivity easily spans several orders of magnitude. The flow rate and the velocity variations are primarily influenced by the conductivity variations and are only to a small extent influenced by the volume variations in the channel. The average specific area of the whole channel exhibits small variations. The hydraulic and transport properties of hypothetical fractures containing several channels are investigated by randomly picking several of the generated channels, coupling them in parallel and subjecting them to the same hydraulic head difference. The flow rate and residence time distribution of the coupled channels is used to investigate the dispersion properties of the fracture. It was found that the dispersion expressed as Peclet numbers was on the order of 1 to 4 for most of the distributions used but could attain very large Peclet numbers for (unrealistically) narrow aperture distributions. Simulations of breakthrough curves for tracers in single fracture flow experiments indicate that when few channels participate and the dispersion in the individual channels is small, the breakthrough curve is expected not to be entirely smooth but to contain distinct plateaus. This property has been noted in several experiments. (orig./HP)

  9. Feasibility Studies of Alpha-Channeling in Mirror Machines

    International Nuclear Information System (INIS)

    Zhmoginov, A.I.; Fisch, N.J.

    2010-01-01

    The linear magnetic trap is an attractive concept both for fusion reactors and for other plasma applications due to its relative engineering simplicity and high-beta operation. Applying the α-channeling technique to linear traps, such as mirror machines, can benefit this concept by efficiently redirecting α particle energy to fuel ion heating or by otherwise sustaining plasma confinement, thus increasing the effective fusion reactivity. To identify waves suitable for α-channeling a rough optimization of the energy extraction rate with respect to the wave parameters is performed. After the optimal regime is identified, a systematic search for modes with similar parameters in mirror plasmas is performed, assuming quasi-longitudinal or quasi-transverse wave propagation. Several modes suitable for α particle energy extraction are identified for both reactor designs and for proof- of-principle experiments.

  10. Microwell Arrays for Studying Many Individual Cells

    Science.gov (United States)

    Folch, Albert; Kosar, Turgut Fettah

    2009-01-01

    "Laboratory-on-a-chip" devices that enable the simultaneous culturing and interrogation of many individual living cells have been invented. Each such device includes a silicon nitride-coated silicon chip containing an array of micromachined wells sized so that each well can contain one cell in contact or proximity with a patch clamp or other suitable single-cell-interrogating device. At the bottom of each well is a hole, typically 0.5 m wide, that connects the well with one of many channels in a microfluidic network formed in a layer of poly(dimethylsiloxane) on the underside of the chip. The microfluidic network makes it possible to address wells (and, thus, cells) individually to supply them with selected biochemicals. The microfluidic channels also provide electrical contact to the bottoms of the wells.

  11. A new Infrared Atmospheric Sounding Interferometer channel selection and assessment of its impact on Met Office NWP forecasts

    Science.gov (United States)

    Noh, Young-Chan; Sohn, Byung-Ju; Kim, Yoonjae; Joo, Sangwon; Bell, William; Saunders, Roger

    2017-11-01

    A new set of Infrared Atmospheric Sounding Interferometer (IASI) channels was re-selected from 314 EUMETSAT channels. In selecting channels, we calculated the impact of the individually added channel on the improvement in the analysis outputs from a one-dimensional variational analysis (1D-Var) for the Unified Model (UM) data assimilation system at the Met Office, using the channel score index (CSI) as a figure of merit. Then, 200 channels were selected in order by counting each individual channel's CSI contribution. Compared with the operationally used 183 channels for the UM at the Met Office, the new set shares 149 channels, while the other 51 channels are new. Also examined is the selection from the entropy reduction method with the same 1D-Var approach. Results suggest that channel selection can be made in a more objective fashion using the proposed CSI method. This is because the most important channels can be selected across the whole IASI observation spectrum. In the experimental trial runs using the UM global assimilation system, the new channels had an overall neutral impact in terms of improvement in forecasts, as compared with results from the operational channels. However, upper-tropospheric moist biases shown in the control run with operational channels were significantly reduced in the experimental trial with the newly selected channels. The reduction of moist biases was mainly due to the additional water vapor channels, which are sensitive to the upper-tropospheric water vapor.

  12. Thermodynamics of competitive molecular channel transport: application to artificial nuclear pores.

    Science.gov (United States)

    Bauer, Wolfgang R; Nadler, Walter

    2010-12-13

    In an analytical model channel transport is analyzed as a function of key parameters, determining efficiency and selectivity of particle transport in a competitive molecular environment. These key parameters are the concentration of particles, solvent-channel exchange dynamics, as well as particle-in-channel- and interparticle interaction. These parameters are explicitly related to translocation dynamics and channel occupation probability. Slowing down the exchange dynamics at the channel ends, or elevating the particle concentration reduces the in-channel binding strength necessary to maintain maximum transport. Optimized in-channel interaction may even shift from binding to repulsion. A simple equation gives the interrelation of access dynamics and concentration at this transition point. The model is readily transferred to competitive transport of different species, each of them having their individual in-channel affinity. Combinations of channel affinities are determined which differentially favor selectivity of certain species on the cost of others. Selectivity for a species increases if its in-channel binding enhances the species' translocation probability when compared to that of the other species. Selectivity increases particularly for a wide binding site, long channels, and fast access dynamics. Recent experiments on competitive transport of in-channel binding and inert molecules through artificial nuclear pores serve as a paradigm for our model. It explains qualitatively and quantitatively how binding molecules are favored for transport at the cost of the transport of inert molecules.

  13. A Feedback-Controlled Mandibular Positioner Identifies Individuals With Sleep Apnea Who Will Respond to Oral Appliance Therapy.

    Science.gov (United States)

    Remmers, John E; Topor, Zbigniew; Grosse, Joshua; Vranjes, Nikola; Mosca, Erin V; Brant, Rollin; Bruehlmann, Sabina; Charkhandeh, Shouresh; Zareian Jahromi, Seyed Abdolali

    2017-07-15

    Mandibular protruding oral appliances represent a potentially important therapy for obstructive sleep apnea (OSA). However, their clinical utility is limited by a less-than-ideal efficacy rate and uncertainty regarding an efficacious mandibular position, pointing to the need for a tool to assist in delivery of the therapy. The current study assesses the ability to prospectively identify therapeutic responders and determine an efficacious mandibular position. Individuals (n = 202) with OSA participated in a blinded, 2-part investigation. A system for identifying therapeutic responders was developed in part 1 (n = 149); the predictive accuracy of this system was prospectively evaluated on a new population in part 2 (n = 53). Each participant underwent a 2-night, in-home feedback-controlled mandibular positioner (FCMP) test, followed by treatment with a custom oral appliance and an outcome study with the oral appliance in place. A machine learning classification system was trained to predict therapeutic outcome on data obtained from FCMP studies on part 1 participants. The accuracy of this trained system was then evaluated on part 2 participants by examining the agreement between prospectively predicted outcome and observed outcome. A predicted efficacious mandibular position was derived from each FCMP study. Predictive accuracy was as follows: sensitivity 85%; specificity 93%; positive predictive value 97%; and negative predictive value 72%. Of participants correctly predicted to respond to therapy, the predicted mandibular protrusive position proved efficacious in 86% of cases. An unattended, in-home FCMP test prospectively identifies individuals with OSA who will respond to oral appliance therapy and provides an efficacious mandibular position. The trial that this study reports on is registered on www.clinicaltrials.gov, ID NCT03011762, study name: Feasibility and Predictive Accuracy of an In-Home Computer Controlled Mandibular Positioner in Identifying Favourable

  14. An Effective Channel Allocation Scheme to Reduce Co-Channel and Adjacent Channel Interference for WMN Backhaul

    International Nuclear Information System (INIS)

    Abbasi, S.; Ismaili, I.A.; Khuhawar, F.Y.

    2016-01-01

    Two folded work presents channel allocation scheme sustaining channel orthogonality and channel spacing to reduce CCI (Co-Channel Interference) and ACI (Adjacent Channel Interference) for inter flow of an intra-flow link. Proposed scheme as a part of radio resource allocation is applied on infrastructure based backhaul of wireless mesh network using directional antennas. The proposed approach is applied separately on 2.4 and 5GHz bands. Interference of connectivity graph is modelled by strongly connected directed graph and greedy algorithms are used for channel allocation. We have used OPNET Modeller suite to simulate network models for this research. The proposed arrangement reduces the channel interference and increases system throughput. In this research, the influence of channel is computed in terms of network throughput and delay. (author)

  15. Architecture of channel-belt deposits in an aggrading shallow sandbed braided river: the lower Niobrara River, northeast Nebraska

    Science.gov (United States)

    Skelly, Raymond L.; Bristow, Charlie S.; Ethridge, Frank G.

    2003-05-01

    Architecture of recent channel-belt deposits of the Niobrara River, northeast Nebraska, USA, records the response of a sandy braided river to rapid base-level rise. Up to 3 m of aggradation has occurred within the lower 14 km of the Niobrara River since the mid-1950s as a result of base-level rise at the confluence of the Niobrara and Missouri Rivers. Aerial photographs and channel surveys indicate that the lower Niobrara has evolved from a relatively deep, stable channel with large, bank-attached braid bars to a relatively shallow, aggrading channel with braid bars and smaller secondary channels. Architecture of channel-belt deposits associated with the recent aggradation has been defined using ground-penetrating radar (GPR) and vibracores. The channel-belt deposits exhibit a series of amalgamated channel fills and braid bar complexes (i.e., macroforms). Radar facies identified in the GPR data represent architectural elements of the braid bar complexes, large and small bedforms [two-dimensional (2-D) and three-dimensional (3-D) dunes], and channels. Individual braid bars appear to consist of basal high-flow and upper low-flow components. Preservation of the complete, high-flow bar geometry is generally incomplete due to frequent migration of smaller scale, secondary channels within the channel belt (i.e., braided channel network) at low discharges. The large-scale stratification of the braid bar deposits is dominated by cross-channel and upstream accretion. Elements of downstream accretion are also recognized. These accretion geometries have not been documented previously in similar sandy braided rivers. Braid bar deposits with low-flow modification (e.g., incision by secondary channels) are recognized in the deeper portions of the deposits imaged by GPR. Preservation of braid bars, with both high- and low-flow components, is a result of the rapid base-level rise and channel-bed aggradation experienced by the Niobrara River over the past 45 years. Recent avulsion

  16. Effects of relativistic and channel focusing on q-Gaussian laser beam propagating in a preformed parabolic plasma channel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Li; Hong, Xue-Ren, E-mail: hxr_nwnu@163.com; Sun, Jian-An, E-mail: sunja@nwnu.edu.cn; Tang, Rong-An; Yang, Yang; Zhou, Wei-Jun; Tian, Jian-Min; Duan, Wen-Shan

    2017-07-12

    The propagation of q-Gaussian laser beam in a preformed plasma channel is investigated by means of the variational method. A differential equation for the spot size has been obtained by including the effects of relativistic self-focusing, ponderomotive self-channeling and preformed channel focusing. The propagation behaviors and their corresponding physical conditions are identified. The comparison of the propagation between q-Gaussian and Gaussian laser beams is done by theoretical and numerical analysis. It is shown that, in the same channel, the focusing power of q-Gaussian laser beam is lower than that of Gaussian laser beam, i.e., the q-Gaussian laser beam is easier to focus than Gaussian laser beam. - Highlights: • Some behaviors for Gaussian laser are also found for q-Gaussian one. • The parameter regions corresponding to different laser behaviors are given. • Influence of q on the laser propagation behavior is obvious. • The q-Gaussian laser beam is easier to focus than the Gaussian one.

  17. Effects of relativistic and channel focusing on q-Gaussian laser beam propagating in a preformed parabolic plasma channel

    International Nuclear Information System (INIS)

    Wang, Li; Hong, Xue-Ren; Sun, Jian-An; Tang, Rong-An; Yang, Yang; Zhou, Wei-Jun; Tian, Jian-Min; Duan, Wen-Shan

    2017-01-01

    The propagation of q-Gaussian laser beam in a preformed plasma channel is investigated by means of the variational method. A differential equation for the spot size has been obtained by including the effects of relativistic self-focusing, ponderomotive self-channeling and preformed channel focusing. The propagation behaviors and their corresponding physical conditions are identified. The comparison of the propagation between q-Gaussian and Gaussian laser beams is done by theoretical and numerical analysis. It is shown that, in the same channel, the focusing power of q-Gaussian laser beam is lower than that of Gaussian laser beam, i.e., the q-Gaussian laser beam is easier to focus than Gaussian laser beam. - Highlights: • Some behaviors for Gaussian laser are also found for q-Gaussian one. • The parameter regions corresponding to different laser behaviors are given. • Influence of q on the laser propagation behavior is obvious. • The q-Gaussian laser beam is easier to focus than the Gaussian one.

  18. Improving the service life and performance of CANDU fuel channels

    International Nuclear Information System (INIS)

    Causey, A.R.; Cheadle, B.A.; Coleman, C.E.; Price, E.G.

    1996-02-01

    The development objective for CANDU fuel channels is to produce a design that can operate for 40 years at 90% capacity. Steady progress toward this objective is being made. The factors that determine the life of a CANDU fuel channel are reviewed and the processes necessary to achieve the objectives identified. Performance of future fuel channels will be enhanced by reduced operating costs, increased safety margins to postulated accident conditions, and reduced retubing costs compared with those for current channels. The approaches to these issues are discussed briefly in this report. (author). 14 refs., 1 tab., 8 figs

  19. SK2 channels regulate mitochondrial respiration and mitochondrial Ca2+ uptake

    NARCIS (Netherlands)

    Honrath, Birgit; Matschke, Lina; Meyer, Tammo; Magerhans, Lena; Perocchi, Fabiana; Ganjam, Goutham K; Zischka, Hans; Krasel, Cornelius; Gerding, Albert; Bakker, Barbara M; Bünemann, Moritz; Strack, Stefan; Decher, Niels; Culmsee, Carsten; Dolga, Amalia M

    Mitochondrial calcium ([Ca(2+)]m) overload and changes in mitochondrial metabolism are key players in neuronal death. Small conductance calcium-activated potassium (SK) channels provide protection in different paradigms of neuronal cell death. Recently, SK channels were identified at the inner

  20. Role of vascular potassium channels in the regulation of renal hemodynamics

    DEFF Research Database (Denmark)

    Sørensen, Charlotte Mehlin; Braunstein, Thomas Hartig; von Holstein-Rathlou, Niels-Henrik

    2012-01-01

    of one or more classes of K+ channels will lead to a change in hemodynamic resistance and therefore of renal blood flow and glomerular filtration pressure. Through these effects, the activity of renal vascular K+ channels influences renal salt and water excretion, fluid homeostasis, and ultimately blood...... pressure. Four main classes of K+ channels [calcium activated (KCa), inward rectifier (Kir), voltage activated (KV), and ATP sensitive (KATP)] are found in the renal vasculature. Several in vitro experiments have suggested a role for individual classes of K+ channels in the regulation of renal vascular...... function. Results from in vivo experiments are sparse. We discuss the role of the different classes of renal vascular K+ channels and their possible role in the integrated function of the renal microvasculature. Since several pathological conditions, among them hypertension, are associated with alterations...

  1. Voltage-gated proton channel is expressed on phagosomes

    International Nuclear Information System (INIS)

    Okochi, Yoshifumi; Sasaki, Mari; Iwasaki, Hirohide; Okamura, Yasushi

    2009-01-01

    Voltage-gated proton channel has been suggested to help NADPH oxidase activity during respiratory burst of phagocytes through its activities of compensating charge imbalance and regulation of pH. In phagocytes, robust production of reactive oxygen species occurs in closed membrane compartments, which are called phagosomes. However, direct evidence for the presence of voltage-gated proton channels in phagosome has been lacking. In this study, the expression of voltage-gated proton channels was studied by Western blot with the antibody specific to the voltage-sensor domain protein, VSOP/Hv1, that has recently been identified as the molecular correlate for the voltage-gated proton channel. Phagosomal membranes of neutrophils contain VSOP/Hv1 in accordance with subunits of NADPH oxidases, gp91, p22, p47 and p67. Superoxide anion production upon PMA activation was significantly reduced in neutrophils from VSOP/Hv1 knockout mice. These are consistent with the idea that voltage-gated proton channels help NADPH oxidase in phagocytes to produce reactive oxygen species.

  2. A MHD channel study for the ETF conceptual design

    Science.gov (United States)

    Wang, S. Y.; Staiger, P. J.; Smith, J. M.

    1981-01-01

    The procedures and computations used to identify an MHD channel for a 540 mW(I) EFT-scale plant are presented. Under the assumed constraints of maximum E(x), E(y), J(y) and Beta; results show the best plant performance is obtained for active length, L is approximately 12 M, whereas in the initial ETF studies, L is approximately 16 M. As MHD channel length is reduced from 16 M, the channel enthalpy extraction falls off, slowly. This tends to reduce the MHD power output; however, the shorter channels result in lower heat losses to the MHD channel cooling water which allows for the incorporation of more low pressure boiler feedwater heaters into the system and an increase in steam plant efficiency. The net result of these changes is a net increase in the over all MHD/steam plant efficiency. In addition to the sensitivity of various channel parameters, the trade-offs between the level of oxygen enrichment and the electrical stress on the channel are also discussed.

  3. Gating of human ClC-2 chloride channels and regulation by carboxy-terminal domains.

    Science.gov (United States)

    Garcia-Olivares, Jennie; Alekov, Alexi; Boroumand, Mohammad Reza; Begemann, Birgit; Hidalgo, Patricia; Fahlke, Christoph

    2008-11-15

    Eukaryotic ClC channels are dimeric proteins with each subunit forming an individual protopore. Single protopores are gated by a fast gate, whereas the slow gate is assumed to control both protopores through a cooperative movement of the two carboxy-terminal domains. We here study the role of the carboxy-terminal domain in modulating fast and slow gating of human ClC-2 channels, a ubiquitously expressed ClC-type chloride channel involved in transepithelial solute transport and in neuronal chloride homeostasis. Partial truncation of the carboxy-terminus abolishes function of ClC-2 by locking the channel in a closed position. However, unlike other isoforms, its complete removal preserves function of ClC-2. ClC-2 channels without the carboxy-terminus exhibit fast and slow gates that activate and deactivate significantly faster than in WT channels. In contrast to the prevalent view, a single carboxy-terminus suffices for normal slow gating, whereas both domains regulate fast gating of individual protopores. Our findings demonstrate that the carboxy-terminus is not strictly required for slow gating and that the cooperative gating resides in other regions of the channel protein. ClC-2 is expressed in neurons and believed to open at negative potentials and increased internal chloride concentrations after intense synaptic activity. We propose that the function of the ClC-2 carboxy-terminus is to slow down the time course of channel activation in order to stabilize neuronal excitability.

  4. Identifying individuals with antisocial personality disorder using resting-state FMRI.

    Directory of Open Access Journals (Sweden)

    Yan Tang

    Full Text Available Antisocial personality disorder (ASPD is closely connected to criminal behavior. A better understanding of functional connectivity in the brains of ASPD patients will help to explain abnormal behavioral syndromes and to perform objective diagnoses of ASPD. In this study we designed an exploratory data-driven classifier based on machine learning to investigate changes in functional connectivity in the brains of patients with ASPD using resting state functional magnetic resonance imaging (fMRI data in 32 subjects with ASPD and 35 controls. The results showed that the classifier achieved satisfactory performance (86.57% accuracy, 77.14% sensitivity and 96.88% specificity and could extract stabile information regarding functional connectivity that could be used to discriminate ASPD individuals from normal controls. More importantly, we found that the greatest change in the ASPD subjects was uncoupling between the default mode network and the attention network. Moreover, the precuneus, superior parietal gyrus and cerebellum exhibited high discriminative power in classification. A voxel-based morphometry analysis was performed and showed that the gray matter volumes in the parietal lobule and white matter volumes in the precuneus were abnormal in ASPD compared to controls. To our knowledge, this study was the first to use resting-state fMRI to identify abnormal functional connectivity in ASPD patients. These results not only demonstrated good performance of the proposed classifier, which can be used to improve the diagnosis of ASPD, but also elucidate the pathological mechanism of ASPD from a resting-state functional integration viewpoint.

  5. IT IN COMMERCE: E-COMMERCE AND OMNI-CHANNEL SALES IN RUSSIA

    OpenAIRE

    PHILIPP A. ANTIPIN

    2017-01-01

    The article discusses the use of information technologies and possibilities provided by the Internet in commerce. The global and European experience of omni-channel sales is discussed. The prospects and conditions of the development of e-commerce and omni-channel sales are identified.

  6. Dopamine negatively modulates the NCA ion channels in C. elegans.

    Science.gov (United States)

    Topalidou, Irini; Cooper, Kirsten; Pereira, Laura; Ailion, Michael

    2017-10-01

    The NALCN/NCA ion channel is a cation channel related to voltage-gated sodium and calcium channels. NALCN has been reported to be a sodium leak channel with a conserved role in establishing neuronal resting membrane potential, but its precise cellular role and regulation are unclear. The Caenorhabditis elegans orthologs of NALCN, NCA-1 and NCA-2, act in premotor interneurons to regulate motor circuit activity that sustains locomotion. Recently we found that NCA-1 and NCA-2 are activated by a signal transduction pathway acting downstream of the heterotrimeric G protein Gq and the small GTPase Rho. Through a forward genetic screen, here we identify the GPCR kinase GRK-2 as a new player affecting signaling through the Gq-Rho-NCA pathway. Using structure-function analysis, we find that the GPCR phosphorylation and membrane association domains of GRK-2 are required for its function. Genetic epistasis experiments suggest that GRK-2 acts on the D2-like dopamine receptor DOP-3 to inhibit Go signaling and positively modulate NCA-1 and NCA-2 activity. Through cell-specific rescuing experiments, we find that GRK-2 and DOP-3 act in premotor interneurons to modulate NCA channel function. Finally, we demonstrate that dopamine, through DOP-3, negatively regulates NCA activity. Thus, this study identifies a pathway by which dopamine modulates the activity of the NCA channels.

  7. An investigation of 'sparse channel networks'. Characteristic behaviours and their causes

    International Nuclear Information System (INIS)

    Black, J.H.; Barker, J.A.; Woodman, N.D.

    2007-09-01

    This report represents a third study in a series concerned with groundwater flow in poorly permeable fractured crystalline rocks. The study has brought together three linked, but distinct, elements; a mathematical analysis of the intersection of ellipses, a review of field measurements associated with nuclear waste repository investigations and probabilistic simulations using a lattice network numerical model. We conclude that the model of channels that traverse fracture intersections without necessarily branching is a very likely representation of reality. More generally, assembling all the lines of evidence, it is suggested that groundwater flow systems in fractured crystalline rocks in the environs of underground laboratories have the following characteristics: Groundwater flows within a sparse network of channels just above the percolation limit. The frequency of intersections is low in that individual channels extend considerable distances between significant junctions. Individual channels often extend over many fracture surfaces and the resulting flow system is only weakly related to the density or size of mappable fractures. The sparseness of systems compared to the size of drifts and tunnels means that only a very few flow channels are intersected by drifts and tunnels. Highly convergent flow is required to connect to the rest of the network and this is misinterpreted as a skin of low hydraulic conductivity. Systems are so sparse that they are controlled by a few 'chokes' that give rise to compartments of head, and probably, of groundwater chemistry. Channels occur on all fracture planes, including those within fracture zones, and although the characteristics of the fracture zone channel networks may differ from those in surrounding rocks, they are nonetheless still channel networks. The actively flowing sparse channel network, occurring within any particular rock, is a naturally selected, small sub-set of the available channels. Hence, there are many

  8. Evolutionary and Structural Perspectives of Plant Cyclic Nucleotide Gated Cation Channels

    Directory of Open Access Journals (Sweden)

    Alice Kira Zelman

    2012-05-01

    Full Text Available Ligand-gated cation channels are a frequent component of signaling cascades in eukaryotes. Eukaryotes contain numerous diverse gene families encoding ion channels, some of which are shared and some of which are unique to particular kingdoms. Among the many different types are cyclic nucleotide-gated channels (CNGCs. CNGCs are cation channels with varying degrees of ion conduction selectivity. They are implicated in numerous signaling pathways and permit diffusion of divalent and monovalent cations, including Ca2+ and K+. CNGCs are present in both plant and animal cells, typically in the plasma membrane; recent studies have also documented their presence in prokaryotes. All eukaryote CNGC polypeptides have a cyclic nucleotide binding domain (CNBD and a calmodulin binding domain (CaMBD as well as a 6 transmembrane/1 pore tertiary structure. This review summarizes existing knowledge about the functional domains present in these cation-conducting channels, and considers the evidence indicating that plant and animal CNGCs evolved separately. Additionally, an amino acid motif that is only found in the phosphate binding cassette and hinge regions of plant CNGCs, and is present in all experimentally confirmed CNGCs but no other channels was identified. This CNGC-specific amino acid motif provides an additional diagnostic tool to identify plant CNGCs, and can increase confidence in the annotation of open reading frames in newly sequenced genomes as putative CNGCs. Conversely, the absence of the motif in some plant sequences currently identified as probable CNGCs may suggest that they are misannotated or protein fragments.

  9. Evolutionary and structural perspectives of plant cyclic nucleotide-gated cation channels

    KAUST Repository

    Zelman, Alice K.

    2012-05-29

    Ligand-gated cation channels are a frequent component of signaling cascades in eukaryotes. Eukaryotes contain numerous diverse gene families encoding ion channels, some of which are shared and some of which are unique to particular kingdoms. Among the many different types are cyclic nucleotide-gated channels (CNGCs). CNGCs are cation channels with varying degrees of ion conduction selectivity. They are implicated in numerous signaling pathways and permit diffusion of divalent and monovalent cations, including Ca2+ and K+. CNGCs are present in both plant and animal cells, typically in the plasma membrane; recent studies have also documented their presence in prokaryotes. All eukaryote CNGC polypeptides have a cyclic nucleotide-binding domain and a calmodulin binding domain as well as a six transmembrane/one pore tertiary structure. This review summarizes existing knowledge about the functional domains present in these cation-conducting channels, and considers the evidence indicating that plant and animal CNGCs evolved separately. Additionally, an amino acid motif that is only found in the phosphate binding cassette and hinge regions of plant CNGCs, and is present in all experimentally confirmed CNGCs but no other channels was identified. This CNGC-specific amino acid motif provides an additional diagnostic tool to identify plant CNGCs, and can increase confidence in the annotation of open reading frames in newly sequenced genomes as putative CNGCs. Conversely, the absence of the motif in some plant sequences currently identified as probable CNGCs may suggest that they are misannotated or protein fragments. 2012 Zelman, Dawe, Gehring and Berkowitz.

  10. Groundwater Discharge along a Channelized Coastal Plain Stream

    Energy Technology Data Exchange (ETDEWEB)

    LaSage, Danita M [Ky Dept for natural resources, Div of Mine Permits; Sexton, Joshua L [JL Sexton and Son; Mukherjee, Abhijit [Univ of Tx, Jackson School of Geosciences, Bur of Econ. Geology; Fryar, Alan E [Univ of KY, Dept of Earth and Geoligical Sciences; Greb, Stephen F [Univ of KY, KY Geological Survey

    2015-10-01

    In the Coastal Plain of the southeastern USA, streams have commonly been artificially channelized for flood control and agricultural drainage. However, groundwater discharge along such streams has received relatively little attention. Using a combination of stream- and spring-flow measurements, spring temperature measurements, temperature profiling along the stream-bed, and geologic mapping, we delineated zones of diffuse and focused discharge along Little Bayou Creek, a channelized, first-order perennial stream in western Kentucky. Seasonal variability in groundwater discharge mimics hydraulic-head fluctuations in a nearby monitoring well and spring-discharge fluctuations elsewhere in the region, and is likely to reflect seasonal variability in recharge. Diffuse discharge occurs where the stream is incised into the semi-confined regional gravel aquifer, which is comprised of the Mounds Gravel. Focused discharge occurs upstream where the channel appears to have intersected preferential pathways within the confining unit. Seasonal fluctuations in discharge from individual springs are repressed where piping results in bank collapse. Thereby, focused discharge can contribute to the morphological evolution of the stream channel.

  11. Thermodynamics of competitive molecular channel transport: application to artificial nuclear pores.

    Directory of Open Access Journals (Sweden)

    Wolfgang R Bauer

    Full Text Available In an analytical model channel transport is analyzed as a function of key parameters, determining efficiency and selectivity of particle transport in a competitive molecular environment. These key parameters are the concentration of particles, solvent-channel exchange dynamics, as well as particle-in-channel- and interparticle interaction. These parameters are explicitly related to translocation dynamics and channel occupation probability. Slowing down the exchange dynamics at the channel ends, or elevating the particle concentration reduces the in-channel binding strength necessary to maintain maximum transport. Optimized in-channel interaction may even shift from binding to repulsion. A simple equation gives the interrelation of access dynamics and concentration at this transition point. The model is readily transferred to competitive transport of different species, each of them having their individual in-channel affinity. Combinations of channel affinities are determined which differentially favor selectivity of certain species on the cost of others. Selectivity for a species increases if its in-channel binding enhances the species' translocation probability when compared to that of the other species. Selectivity increases particularly for a wide binding site, long channels, and fast access dynamics. Recent experiments on competitive transport of in-channel binding and inert molecules through artificial nuclear pores serve as a paradigm for our model. It explains qualitatively and quantitatively how binding molecules are favored for transport at the cost of the transport of inert molecules.

  12. Immunolocalization and expression of small-conductance calcium-activated potassium channels in human myometrium

    DEFF Research Database (Denmark)

    Rosenbaum, Sofia T; Svalø, Julie; Nielsen, Karsten

    2012-01-01

    Small-conductance calcium-activated potassium (SK3) channels have been detected in human myometrium and we have previously shown a functional role of SK channels in human myometrium in vitro. The aims of this study were to identify the precise localization of SK3 channels and to quantify SK3 m....... This is the first report to provide evidence for a possible role of SK3 channels in human uterine telocytes....

  13. Role of TRP Channels in Dinoflagellate Mechanotransduction.

    Science.gov (United States)

    Lindström, J B; Pierce, N T; Latz, M I

    2017-10-01

    Transient receptor potential (TRP) ion channels are common components of mechanosensing pathways, mainly described in mammals and other multicellular organisms. To gain insight into the evolutionary origins of eukaryotic mechanosensory proteins, we investigated the involvement of TRP channels in mechanosensing in a unicellular eukaryotic protist, the dinoflagellate Lingulodinium polyedra. BLASTP analysis of the protein sequences predicted from the L. polyedra transcriptome revealed six sequences with high similarity to human TRPM2, TRPM8, TRPML2, TRPP1, and TRPP2; and characteristic TRP domains were identified in all sequences. In a phylogenetic tree including all mammalian TRP subfamilies and TRP channel sequences from unicellular and multicellular organisms, the L. polyedra sequences grouped with the TRPM, TPPML, and TRPP clades. In pharmacological experiments, we used the intrinsic bioluminescence of L. polyedra as a reporter of mechanoresponsivity. Capsaicin and RN1734, agonists of mammalian TRPV, and arachidonic acid, an agonist of mammalian TRPV, TRPA, TRPM, and Drosophila TRP, all stimulated bioluminescence in L. polyedra. Mechanical stimulation of bioluminescence, but not capsaicin-stimulated bioluminescence, was inhibited by gadolinium (Gd 3+ ), a general inhibitor of mechanosensitive ion channels, and the phospholipase C (PLC) inhibitor U73122. These pharmacological results are consistent with the involvement of TRP-like channels in mechanosensing by L. polyedra. The TRP channels do not appear to be mechanoreceptors but rather are components of the mechanotransduction signaling pathway and may be activated via a PLC-dependent mechanism. The presence and function of TRP channels in a dinoflagellate emphasize the evolutionary conservation of both the channel structures and their functions.

  14. Structural inferences for the native skeletal muscle sodium channel as derived from patterns of endogenous proteolysis

    International Nuclear Information System (INIS)

    Kraner, S.; Yang, J.; Barchi, R.

    1989-01-01

    The alpha subunit (Mr approximately 260,000) of the rat skeletal muscle sodium channel is sensitive to cleavage by endogenous proteases during the isolation of muscle surface membrane. Antisera against synthetic oligopeptides were used to map the resultant fragments in order to identify protease-sensitive regions of the channel's structure in its native membrane environment. Antibodies to the amino terminus labeled major fragments of Mr approximately 130,000 and 90,000 and lesser amounts of other peptides as small as Mr approximately 12,000. Antisera to epitopes within the carboxyl-terminal half of the primary sequence recognized two fragments of Mr approximately 110,000 and 78,000. Individual antisera also selectively labeled smaller polypeptides in the most extensively cleaved preparations. The immunoreactivity patterns of monoclonal antibodies previously raised against the purified channel were then surveyed. The binding sites for one group of monoclonals, including several that recognize subtype-specific epitopes in the channel structure, were localized within a 12-kDa fragment near the amino terminus. The distribution of carbohydrate along the primary structure of the channel was also assessed by quantitating 125 I-wheat germ agglutinin and 125I-concanavalin A binding to the proteolytic peptides. Most of the carbohydrate detected by these lectins was located between 22 and 90 kDa from the amino terminus of the protein. No lectin binding was detected to fragments arising from carboxyl-terminal half of the protein. These results were analyzed in terms of current models of sodium channel tertiary structure. In its normal membrane environment, the skeletal muscle sodium channel appears sensitive to cleavage by endogenous proteases in regions predicted to link the four repeat domains on the cytoplasmic side of the membrane while the repeat domains themselves are resistant to proteolysis

  15. Citizens and service channels: channel choice and channel management implications

    NARCIS (Netherlands)

    Pieterson, Willem Jan

    2010-01-01

    The arrival of electronic channels in the 1990s has had a huge impact on governmental service delivery. The new channels have led to many new opportunities to improve public service delivery, not only in terms of citizen satisfaction, but also in cost reduction for governmental agencies. However,

  16. A computational design approach for virtual screening of peptide interactions across K+ channel families

    Directory of Open Access Journals (Sweden)

    Craig A. Doupnik

    2015-01-01

    Full Text Available Ion channels represent a large family of membrane proteins with many being well established targets in pharmacotherapy. The ‘druggability’ of heteromeric channels comprised of different subunits remains obscure, due largely to a lack of channel-specific probes necessary to delineate their therapeutic potential in vivo. Our initial studies reported here, investigated the family of inwardly rectifying potassium (Kir channels given the availability of high resolution crystal structures for the eukaryotic constitutively active Kir2.2 channel. We describe a ‘limited’ homology modeling approach that can yield chimeric Kir channels having an outer vestibule structure representing nearly any known vertebrate or invertebrate channel. These computationally-derived channel structures were tested in silico for ‘docking’ to NMR structures of tertiapin (TPN, a 21 amino acid peptide found in bee venom. TPN is a highly selective and potent blocker for the epithelial rat Kir1.1 channel, but does not block human or zebrafish Kir1.1 channel isoforms. Our Kir1.1 channel-TPN docking experiments recapitulated published in vitro findings for TPN-sensitive and TPN-insensitive channels. Additionally, in silico site-directed mutagenesis identified ‘hot spots’ within the channel outer vestibule that mediate energetically favorable docking scores and correlate with sites previously identified with in vitro thermodynamic mutant-cycle analysis. These ‘proof-of-principle’ results establish a framework for virtual screening of re-engineered peptide toxins for interactions with computationally derived Kir channels that currently lack channel-specific blockers. When coupled with electrophysiological validation, this virtual screening approach may accelerate the drug discovery process, and can be readily applied to other ion channels families where high resolution structures are available.

  17. Single-channel kinetics of BK (Slo1 channels

    Directory of Open Access Journals (Sweden)

    Yanyan eGeng

    2015-01-01

    Full Text Available 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 5 closed states on the upper tier and 5 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.

  18. Sedimentary Facies Mapping Based on Tidal Channel Network and Topographic Features

    Science.gov (United States)

    Ryu, J. H.; Lee, Y. K.; Kim, K.; Kim, B.

    2015-12-01

    Tidal flats on the west coast of Korea suffer intensive changes in their surface sedimentary facies as a result of the influence of natural and artificial changes. Spatial relationships between surface sedimentary facies distribution and benthic environments were estimated for the open-type Ganghwa tidal flat and semi closed-type Hwangdo tidal flat, Korea. In this study, we standardized the surface sedimentary facies and tidal channel index of the channel density, distance, thickness and order. To extract tidal channel information, we used remotely sensed data, such as those from the Korea Multi-Purpose Satellite (KOMPSAT)-2, KOMPSAT-3, and aerial photographs. Surface sedimentary facies maps were generated based on field data using an interpolation method.The tidal channels in each sediment facies had relatively constant meandering patterns, but the density and complexity were distinguishable. The second fractal dimension was 1.7-1.8 in the mud flat, about 1.4 in the mixed flat, and about 1.3 in the sand flat. The channel density was 0.03-0.06 m/m2 in the mud flat and less than 0.02 m/m2 in the mixed and sand flat areas of the two test areas. Low values of the tidal channel index, which indicated a simple pattern of tidal channel distribution, were identified at areas having low elevation and coarse-grained sediments. By contrast, high values of the tidal channel index, which indicated a dendritic pattern of tidal channel distribution, were identified at areas having high elevation and fine-grained sediments. Surface sediment classification based on remotely sensed data must circumspectly consider an effective critical grain size, water content, local topography, and intertidal structures.

  19. Identification of Distribution Channels to Create Sustainable Vegetable Prices

    Directory of Open Access Journals (Sweden)

    Aflit Nuryulia Praswati

    2017-12-01

    Full Text Available The price of vegetables has a role as a contributor to the rate of inflation. Currently the number of vegetable production in Boyolali region can no longer meet the needs of local communities. The limited amount of vegetable production and the inhibition of the vegetable distribution channel creates a scarcity of vegetables that result in price increases. This study aims to identify the distribution channel and the formation of vegetable prices derived from Boyolali area. The method used in this research is quantitative and qualitative. Respondents from this study consisted of farmers, wholesalers, small trader and end consumers. The type of distribution channel prevailing in Boyolali area are traditional and modern distribution channels. Intermediate distribution channels play a greater role in determining vegetable prices. If farmers want to improve their economic condition, it needs innovation and creativity in the process of planting, harvesting, packaging and marketing vegetable products.

  20. Identifying the effects of education on the ability to cope with a disability among individuals with disabilities

    DEFF Research Database (Denmark)

    Bengtsson, Steen; Gupta, Nabanita Datta

    2017-01-01

    The literature on disability has suggested that an educated individual with a disability is more likely to better cope with her/his disability than those without education. However, few published studies explore whether the relationship between education and ability to cope with a disability...... is anything more than an association. Using data on disability and accommodation from a large Danish survey from 2012–13 and exploiting a major Danish schooling reform as a natural experiment, we identified a potential causal effect of education on both economic (holding a job) as well as social (cultural...... with a disability indeed had higher levels of both economic and social coping. To some extent, having more knowledge of public support systems and higher motivation explained the better coping among the group of individuals with disabilities who were educated. Our results indicated, however, that a large part...

  1. System-Level Design of a 64-Channel Low Power Neural Spike Recording Sensor.

    Science.gov (United States)

    Delgado-Restituto, Manuel; Rodriguez-Perez, Alberto; Darie, Angela; Soto-Sanchez, Cristina; Fernandez-Jover, Eduardo; Rodriguez-Vazquez, Angel

    2017-04-01

    This paper reports an integrated 64-channel neural spike recording sensor, together with all the circuitry to process and configure the channels, process the neural data, transmit via a wireless link the information and receive the required instructions. Neural signals are acquired, filtered, digitized and compressed in the channels. Additionally, each channel implements an auto-calibration algorithm which individually configures the transfer characteristics of the recording site. The system has two transmission modes; in one case the information captured by the channels is sent as uncompressed raw data; in the other, feature vectors extracted from the detected neural spikes are released. Data streams coming from the channels are serialized by the embedded digital processor. Experimental results, including in vivo measurements, show that the power consumption of the complete system is lower than 330 μW.

  2. Is Kasei Valles (Mars) the largest volcanic channel in the solar system?

    Science.gov (United States)

    Leverington, David W.

    2018-02-01

    With a length of more than 2000 km and widths of up to several hundred kilometers, Kasei Valles is the largest outflow system on Mars. Superficially, the scabland-like character of Kasei Valles is evocative of terrestrial systems carved by catastrophic aqueous floods, and the system is widely interpreted as a product of outbursts from aquifers. However, as at other Martian outflow channels, clear examples of fluvial sedimentary deposits have proven difficult to identify here. Though Kasei Valles lacks several key properties expected of aqueous systems, its basic morphological and contextual properties are aligned with those of ancient volcanic channels on Venus, the Moon, Mercury, and Earth. There is abundant evidence that voluminous effusions of low-viscosity magmas occurred at the head of Kasei Valles, the channel system acted as a conduit for associated flows, and mare-style volcanic plains developed within its terminal basin. Combined mechanical and thermal incision rates of at least several meters per day are estimated to have been readily achieved at Kasei Valles by 20-m-deep magmas flowing with viscosities of 1 Pa s across low topographic slopes underlain by bedrock. If Kasei Valles formed through incision by magma, it would be the largest known volcanic channel in the solar system. The total volume of magma erupted at Kasei Valles is estimated here to have possibly reached or exceeded ∼5 × 106 km3, a volume comparable in magnitude to those that characterize individual Large Igneous Provinces on Earth. Development of other large outflow systems on Mars is expected to have similarly involved eruption of up to millions of cubic kilometers of magma.

  3. A Mathematica package for calculation of planar channeling radiation spectra of relativistic electrons channeled in a diamond-structure single crystal (quantum approach)

    Science.gov (United States)

    Azadegan, B.

    2013-03-01

    The presented Mathematica code is an efficient tool for simulation of planar channeling radiation spectra of relativistic electrons channeled along major crystallographic planes of a diamond-structure single crystal. The program is based on the quantum theory of channeling radiation which has been successfully applied to study planar channeling at electron energies between 10 and 100 MeV. Continuum potentials for different planes of diamond, silicon and germanium single crystals are calculated using the Doyle-Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the one-dimensional Schrödinger equation. The code is designed to calculate the electron wave functions, transverse electron states in the planar continuum potential, transition energies, line widths of channeling radiation and depth dependencies of the population of quantum states. Finally the spectral distribution of spontaneously emitted channeling radiation is obtained. The simulation of radiation spectra considerably facilitates the interpretation of experimental data. Catalog identifier: AEOH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 446 No. of bytes in distributed program, including test data, etc.: 209805 Distribution format: tar.gz Programming language: Mathematica. Computer: Platforms on which Mathematica is available. Operating system: Operating systems on which Mathematica is available. RAM: 1 MB Classification: 7.10. Nature of problem: Planar channeling radiation is emitted by relativistic charged particles during traversing a single crystal in direction parallel to a crystallographic plane. Channeling is modeled as the motion

  4. Microfluidic in-channel multi-electrode platform for neurotransmitter sensing

    Science.gov (United States)

    Kara, A.; Mathault, J.; Reitz, A.; Boisvert, M.; Tessier, F.; Greener, J.; Miled, A.

    2016-03-01

    In this project we present a microfluidic platform with in-channel micro-electrodes for in situ screening of bio/chemical samples through a lab-on-chip system. We used a novel method to incorporate electrochemical sensors array (16x20) connected to a PCB, which opens the way for imaging applications. A 200 μm height microfluidic channel was bonded to electrochemical sensors. The micro-channel contains 3 inlets used to introduce phosphate buffer saline (PBS), ferrocynide and neurotransmitters. The flow rate was controlled through automated micro-pumps. A multiplexer was used to scan electrodes and perform individual cyclic voltammograms by a custom potentiostat. The behavior of the system was linear in terms of variation of current versus concentration. It was used to detect the neurotransmitters serotonin, dopamine and glutamate.

  5. Identification of cyclic nucleotide gated channels using regular expressions

    KAUST Repository

    Zelman, Alice K.

    2013-09-03

    Cyclic nucleotide-gated channels (CNGCs) are nonselective cation channels found in plants, animals, and some bacteria. They have a six-transmembrane/one- pore structure, a cytosolic cyclic nucleotide-binding domain, and a cytosolic calmodulin-binding domain. Despite their functional similarities, the plant CNGC family members appear to have different conserved amino acid motifs within corresponding functional domains than animal and bacterial CNGCs do. Here we describe the development and application of methods employing plant CNGC-specific sequence motifs as diagnostic tools to identify novel candidate channels in different plants. These methods are used to evaluate the validity of annotations of putative orthologs of CNGCs from plant genomes. The methods detail how to employ regular expressions of conserved amino acids in functional domains of annotated CNGCs and together with Web tools such as PHI-BLAST and ScanProsite to identify novel candidate CNGCs in species including Physcomitrella patens. © Springer Science+Business Media New York 2013.

  6. Strategies for sustainable channel relations in mobile telecom sector

    Directory of Open Access Journals (Sweden)

    Githa Heggde

    2011-01-01

    Full Text Available The telecom sector in India largely comprises of wireless connections for phones. As of today, there are approximately 21 network providers in the country with about 7 per each circle, each offering competitive pricing to the consumers. The main objective of the study is to provide an accurate role for the company executive in developing channel relations. Further to this, the study explores the strategies which can sustain a good working relationship between the company and its channel members in the mobile telecom sector. The constructs identified for developing sustainable relationships were Setting distribution objectives, Channel design, Logistics, Image Building, Inventory management, Channel management, Payment & credit, Promotional assistance, Setting targets, Coverage frequency , Motivating channel members to perform. The sample selected contained distributors from the Mobile telecom sector and company executives/channel managers of leading telecom companies. Factor analysis and Friedman’s test was applied. The findings revealed a correlation in attitude between distributors and the executives. Motivating distributors was rated as the most important strategy by the company. The distributors felt that all channel partners needed to have positive attitude towards the channel while company executives felt that aggression made channel members perform effectively. Such findings will be of use to mobile telecom companies who are new entrants to the Indian market and to existing companies who plan to expand their coverage.

  7. Marine Toxins That Target Voltage-gated Sodium Channels

    Directory of Open Access Journals (Sweden)

    Robert J. French

    2006-04-01

    Full Text Available Abstract: Eukaryotic, voltage-gated sodium (NaV channels are large membrane proteins which underlie generation and propagation of rapid electrical signals in nerve, muscle and heart. Nine different NaV receptor sites, for natural ligands and/or drugs, have been identified, based on functional analyses and site-directed mutagenesis. In the marine ecosystem, numerous toxins have evolved to disrupt NaV channel function, either by inhibition of current flow through the channels, or by modifying the activation and inactivation gating processes by which the channels open and close. These toxins function in their native environment as offensive or defensive weapons in prey capture or deterrence of predators. In composition, they range from organic molecules of varying size and complexity to peptides consisting of ~10-70 amino acids. We review the variety of known NaV-targeted marine toxins, outlining, where known, their sites of interaction with the channel protein and their functional effects. In a number of cases, these natural ligands have the potential applications as drugs in clinical settings, or as models for drug development.

  8. Low-SNR Capacity of MIMO Optical Intensity Channels

    KAUST Repository

    Chaaban, Anas; Rezki, Zouheir; Alouini, Mohamed-Slim

    2017-01-01

    The capacity of the multiple-input multiple-output (MIMO) optical intensity channel is studied, under both average and peak intensity constraints. We focus on low SNR, which can be modeled as the scenario where both constraints proportionally vanish, or where the peak constraint is held constant while the average constraint vanishes. A capacity upper bound is derived, and is shown to be tight at low SNR under both scenarios. The capacity achieving input distribution at low SNR is shown to be a maximally-correlated vector-binary input distribution. Consequently, the low-SNR capacity of the channel is characterized. As a byproduct, it is shown that for a channel with peak intensity constraints only, or with peak intensity constraints and individual (per aperture) average intensity constraints, a simple scheme composed of coded on-off keying, spatial repetition, and maximum-ratio combining is optimal at low SNR.

  9. Low-SNR Capacity of MIMO Optical Intensity Channels

    KAUST Repository

    Chaaban, Anas

    2017-09-18

    The capacity of the multiple-input multiple-output (MIMO) optical intensity channel is studied, under both average and peak intensity constraints. We focus on low SNR, which can be modeled as the scenario where both constraints proportionally vanish, or where the peak constraint is held constant while the average constraint vanishes. A capacity upper bound is derived, and is shown to be tight at low SNR under both scenarios. The capacity achieving input distribution at low SNR is shown to be a maximally-correlated vector-binary input distribution. Consequently, the low-SNR capacity of the channel is characterized. As a byproduct, it is shown that for a channel with peak intensity constraints only, or with peak intensity constraints and individual (per aperture) average intensity constraints, a simple scheme composed of coded on-off keying, spatial repetition, and maximum-ratio combining is optimal at low SNR.

  10. Metaproteomics of saliva identifies human protein markers specific for individuals with periodontitis and dental caries compared to orally healthy controls

    DEFF Research Database (Denmark)

    Belstrøm, Daniel; Jersie-Christensen, Rosa R; Lyon, David

    2016-01-01

    BACKGROUND: The composition of the salivary microbiota has been reported to differentiate between patients with periodontitis, dental caries and orally healthy individuals. To identify characteristics of diseased and healthy saliva we thus wanted to compare saliva metaproteomes from patients...... with periodontitis and dental caries to healthy individuals. METHODS: Stimulated saliva samples were collected from 10 patients with periodontitis, 10 patients with dental caries and 10 orally healthy individuals. The proteins in the saliva samples were subjected to denaturing buffer and digested enzymatically...... and inflammatory markers in periodontitis and dental caries compared to healthy controls. Bacterial proteome profiles and functional annotation were very similar in health and disease. CONCLUSIONS: Overexpression of proteins related to the complement system and inflammation seems to correlate with oral disease...

  11. Molecular Evolution of Slow and Quick Anion Channels (SLACs and QUACs/ALMTs).

    Science.gov (United States)

    Dreyer, Ingo; Gomez-Porras, Judith Lucia; Riaño-Pachón, Diego Mauricio; Hedrich, Rainer; Geiger, Dietmar

    2012-01-01

    Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant) SLAC-like and 422 (402 non-redundant) ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.

  12. Molecular evolution of slow and quick anion channels (SLACs and QUACs/ALMTs

    Directory of Open Access Journals (Sweden)

    Ingo eDreyer

    2012-11-01

    Full Text Available Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant SLAC-like and 422 (402 non-redundant ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.

  13. Note: Optical receiver system for 152-channel magnetoencephalography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin-Mok; Kwon, Hyukchan; Yu, Kwon-kyu; Lee, Yong-Ho; Kim, Kiwoong [Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of)

    2014-11-15

    An optical receiver system composing 13 serial data restore/synchronizer modules and a single module combiner converted optical 32-bit serial data into 32-bit synchronous parallel data for a computer to acquire 152-channel magnetoencephalography (MEG) signals. A serial data restore/synchronizer module identified 32-bit channel-voltage bits from 48-bit streaming serial data, and then consecutively reproduced 13 times of 32-bit serial data, acting in a synchronous clock. After selecting a single among 13 reproduced data in each module, a module combiner converted it into 32-bit parallel data, which were carried to 32-port digital input board in a computer. When the receiver system together with optical transmitters were applied to 152-channel superconducting quantum interference device sensors, this MEG system maintained a field noise level of 3 fT/√Hz @ 100 Hz at a sample rate of 1 kSample/s per channel.

  14. Mechanically Gated Ion Channels in Mammalian Hair Cells

    Directory of Open Access Journals (Sweden)

    Xufeng Qiu

    2018-04-01

    Full Text Available Hair cells in the inner ear convert mechanical stimuli provided by sound waves and head movements into electrical signal. Several mechanically evoked ionic currents with different properties have been recorded in hair cells. The search for the proteins that form the underlying ion channels is still in progress. The mechanoelectrical transduction (MET channel near the tips of stereociliary in hair cells, which is responsible for sensory transduction, has been studied most extensively. Several components of the sensory mechanotransduction machinery in stereocilia have been identified, including the multi-transmembrane proteins tetraspan membrane protein in hair cell stereocilia (TMHS/LHFPL5, transmembrane inner ear (TMIE and transmembrane channel-like proteins 1 and 2 (TMC1/2. However, there remains considerable uncertainty regarding the molecules that form the channel pore. In addition to the sensory MET channel, hair cells express the mechanically gated ion channel PIEZO2, which is localized near the base of stereocilia and not essential for sensory transduction. The function of PIEZO2 in hair cells is not entirely clear but it might have a role in damage sensing and repair processes. Additional stretch-activated channels of unknown molecular identity and function have been found to localize at the basolateral membrane of hair cells. Here, we review current knowledge regarding the different mechanically gated ion channels in hair cells and discuss open questions concerning their molecular composition and function.

  15. [Synopsis about the hypothesis of "information channel" of channel-collateral system].

    Science.gov (United States)

    Chang, Xi-Lang

    2008-10-01

    The author of the present paper founded a theorem about the "incompleteness of single channel structure" (nerve, blood vessel, lymphatic, interspace, aperture, etc.) through quantitative and qualitative analysis about the economic information channel in the human body, which eliminates the probability of single channel structure in the information channel of channel (meridian)-collateral system. After comprehensive analysis on the current researches, the author puts forward a neodoxy, i.e., the body "information channel" structure of the channel-collateral system, mainly follows the distribution regularity of systemic statistics, and is not a single specific entity; various layers of the information channel in the main stems of the channel-collaterals are composed of optimized structure tissues. Hence, the structure of this information channel of channel-collateral system is an overall-optimized, sequential and compatible systemic structure. From this neodoxy, the author brings forward a working principle of channel-collaterals, which is supported theoretically by bio-auxology. The longitudinal distribution of the main stems of meridian-collaterals is considered to result from that in the process of the animal evolution, in the animals moving forward, the microscopic complicated movement of intracorporeal information and energy molecules is related to the forward macroscopic and non-uniform movement of organism in trans-measure. Its impulse and kinetic momentum forms a main vector in the longitudinal direction of the body (the direction of the main stem of channel-collaterals). In order to adapt to and utilize natural regularities, the main stems of the channel-collaterals gradually differentiate and evolve in the living organism, forming a whole system. The "hypothesis of biological origin of channel-collateral system" and "that of information channel of the channel-collaterals in the body" constitute a relatively complete theoretical system framework.

  16. LDPC-based iterative joint source-channel decoding for JPEG2000.

    Science.gov (United States)

    Pu, Lingling; Wu, Zhenyu; Bilgin, Ali; Marcellin, Michael W; Vasic, Bane

    2007-02-01

    A framework is proposed for iterative joint source-channel decoding of JPEG2000 codestreams. At the encoder, JPEG2000 is used to perform source coding with certain error-resilience (ER) modes, and LDPC codes are used to perform channel coding. During decoding, the source decoder uses the ER modes to identify corrupt sections of the codestream and provides this information to the channel decoder. Decoding is carried out jointly in an iterative fashion. Experimental results indicate that the proposed method requires fewer iterations and improves overall system performance.

  17. Channel box

    International Nuclear Information System (INIS)

    Tanabe, Akira.

    1993-01-01

    In a channel box of a BWR type reactor, protruding pads are disposed in axial position on the lateral side of a channel box opposing to a control rod and facing the outer side portion of the control rod in a reactor core loaded state. In the initial loading stage of fuel assemblies, channel fasteners and spacer pads are abutted against each other in the upper portion between the channel boxes sandwiching the control rod therebetween. Further, in the lower portion, a gap as a channel for the movement of the control rod is ensured by the support of fuel support metals. If the channel box is bent toward the control rod along with reactor operation, the pads are abutted against each other to always ensure the gap through which the control rod can move easily. Further, when the pads are brought into contact with each other, the bending deformation of the channel box is corrected by urging to each other. Thus, the control rod can always be moved smoothly to attain reactor safety operation. (N.H.)

  18. Ion Permeation and Mechanotransduction Mechanisms of Mechanosensitive Piezo Channels.

    Science.gov (United States)

    Zhao, Qiancheng; Wu, Kun; Geng, Jie; Chi, Shaopeng; Wang, Yanfeng; Zhi, Peng; Zhang, Mingmin; Xiao, Bailong

    2016-03-16

    Piezo proteins have been proposed as the long-sought-after mechanosensitive cation channels in mammals that play critical roles in various mechanotransduction processes. However, the molecular bases that underlie their ion permeation and mechanotransduction have remained functionally undefined. Here we report our finding of the miniature pore-forming module of Piezo1 that resembles the pore architecture of other trimeric channels and encodes the essential pore properties. We further identified specific residues within the pore module that determine unitary conductance, pore blockage and ion selectivity for divalent and monovalent cations and anions. The non-pore-containing region of Piezo1 confers mechanosensitivity to mechano-insensitive trimeric acid-sensing ion channels, demonstrating that Piezo1 channels possess intrinsic mechanotransduction modules separate from their pore modules. In conclusion, this is the first report on the bona fide pore module and mechanotransduction components of Piezo channels, which define their ion-conducting properties and gating by mechanical stimuli, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Multi-channel electronically scanned cryogenic pressure sensor

    Science.gov (United States)

    Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Kruse, Nancy M. H. (Inventor)

    1995-01-01

    A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multielement array. These dies are bonded at specific sites on a glass, prepatterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

  20. Tourism and information technologies distribution channels: a panorama of the brazilian reality

    Directory of Open Access Journals (Sweden)

    Elisete Santos da Silva Zagheni

    2011-05-01

    Full Text Available Technological evolution has made it possible that the same service may be delivered by means of multiple channels, including in the tourism sector.  The present study proposes to present a bibliographic summary of the distribution channels in tourism and the impact of information technologies (IT in these channels.  Based on exploratory research, 24 scientific papers were analyzed with the intention of identifying a research structure concerning the channels of Brazilian tourism and IT.  We observed that in Brazil, there is a lack of work concerning distribution channels in tourism, highlighting the management of these channels under the view of supply chains.  Beyond this, these papers concentrate on two elements of the channels: means of lodging and hospitality, and travel agencies.  These elements have used direct channels based on IT in order to support service activities and the commercialization of the tourist product.

  1. Revealing dynamically-organized receptor ion channel clusters in live cells by a correlated electric recording and super-resolution single-molecule imaging approach.

    Science.gov (United States)

    Yadav, Rajeev; Lu, H Peter

    2018-03-28

    The N-methyl-d-aspartate (NMDA) receptor ion-channel is activated by the binding of ligands, along with the application of action potential, important for synaptic transmission and memory functions. Despite substantial knowledge of the structure and function, the gating mechanism of the NMDA receptor ion channel for electric on-off signals is still a topic of debate. We investigate the NMDA receptor partition distribution and the associated channel's open-close electric signal trajectories using a combined approach of correlating single-molecule fluorescence photo-bleaching, single-molecule super-resolution imaging, and single-channel electric patch-clamp recording. Identifying the compositions of NMDA receptors, their spatial organization and distributions over live cell membranes, we observe that NMDA receptors are organized inhomogeneously: nearly half of the receptor proteins are individually dispersed; whereas others exist in heterogeneous clusters of around 50 nm in size as well as co-localized within the diffraction limited imaging area. We demonstrate that inhomogeneous interactions and partitions of the NMDA receptors can be a cause of the heterogeneous gating mechanism of NMDA receptors in living cells. Furthermore, comparing the imaging results with the ion-channel electric current recording, we propose that the clustered NMDA receptors may be responsible for the variation in the current amplitude observed in the on-off two-state ion-channel electric signal trajectories. Our findings shed new light on the fundamental structure-function mechanism of NMDA receptors and present a conceptual advancement of the ion-channel mechanism in living cells.

  2. A panel of microsatellites to individually identify leopards and its application to leopard monitoring in human dominated landscapes

    Directory of Open Access Journals (Sweden)

    Selvaraj Velu

    2009-12-01

    Full Text Available Abstract Background Leopards are the most widely distributed of the large cats, ranging from Africa to the Russian Far East. Because of habitat fragmentation, high human population densities and the inherent adaptability of this species, they now occupy landscapes close to human settlements. As a result, they are the most common species involved in human wildlife conflict in India, necessitating their monitoring. However, their elusive nature makes such monitoring difficult. Recent advances in DNA methods along with non-invasive sampling techniques can be used to monitor populations and individuals across large landscapes including human dominated ones. In this paper, we describe a DNA-based method for leopard individual identification where we used fecal DNA samples to obtain genetic material. Further, we apply our methods to non-invasive samples collected in a human-dominated landscape to estimate the minimum number of leopards in this human-leopard conflict area in Western India. Results In this study, 25 of the 29 tested cross-specific microsatellite markers showed positive amplification in 37 wild-caught leopards. These loci revealed varied levels of polymorphism (four-12 alleles and heterozygosity (0.05-0.79. Combining data on amplification success (including non-invasive samples and locus specific polymorphisms, we showed that eight loci provide a sibling probability of identity of 0.0005, suggesting that this panel can be used to discriminate individuals in the wild. When this microsatellite panel was applied to fecal samples collected from a human-dominated landscape, we identified 7 individuals, with a sibling probability of identity of 0.001. Amplification success of field collected scats was up to 72%, and genotype error ranged from 0-7.4%. Conclusion Our results demonstrated that the selected panel of eight microsatellite loci can conclusively identify leopards from various kinds of biological samples. Our methods can be used to

  3. Imaging large cohorts of single ion channels and their activity

    Directory of Open Access Journals (Sweden)

    Katia eHiersemenzel

    2013-09-01

    Full Text Available As calcium is the most important signaling molecule in neurons and secretory cells, amongst many other cell types, it follows that an understanding of calcium channels and their regulation of exocytosis is of vital importance. Calcium imaging using calcium dyes such as Fluo3, or FRET-based dyes that have been used widely has provided invaluable information, which combined with modeling has estimated the sub-types of channels responsible for triggering the exocytotic machinery as well as inferences about the relative distances away from vesicle fusion sites these molecules adopt. Importantly, new super-resolution microscopy techniques, combined with novel Ca2+ indicators and imaginative imaging approaches can now define directly the nanoscale locations of very large cohorts of single channel molecules in relation to single vesicles. With combinations of these techniques the activity of individual channels can be visualized and quantified using novel Ca2+ indicators. Fluorescently labeled specific channel toxins can also be used to localize endogenous assembled channel tetramers. Fluorescence lifetime imaging microscopy and other single-photon-resolution spectroscopic approaches offer the possibility to quantify protein-protein interactions between populations of channels and the SNARE protein machinery for the first time. Together with simultaneous electrophysiology, this battery of quantitative imaging techniques has the potential to provide unprecedented detail describing the locations, dynamic behaviours, interactions and conductance activities of many thousands of channel molecules and vesicles in living cells.

  4. Genome-wide association meta-analysis of 78,308 individuals identifies new loci and genes influencing human intelligence.

    Science.gov (United States)

    Sniekers, Suzanne; Stringer, Sven; Watanabe, Kyoko; Jansen, Philip R; Coleman, Jonathan R I; Krapohl, Eva; Taskesen, Erdogan; Hammerschlag, Anke R; Okbay, Aysu; Zabaneh, Delilah; Amin, Najaf; Breen, Gerome; Cesarini, David; Chabris, Christopher F; Iacono, William G; Ikram, M Arfan; Johannesson, Magnus; Koellinger, Philipp; Lee, James J; Magnusson, Patrik K E; McGue, Matt; Miller, Mike B; Ollier, William E R; Payton, Antony; Pendleton, Neil; Plomin, Robert; Rietveld, Cornelius A; Tiemeier, Henning; van Duijn, Cornelia M; Posthuma, Danielle

    2017-07-01

    Intelligence is associated with important economic and health-related life outcomes. Despite intelligence having substantial heritability (0.54) and a confirmed polygenic nature, initial genetic studies were mostly underpowered. Here we report a meta-analysis for intelligence of 78,308 individuals. We identify 336 associated SNPs (METAL P intelligence in childhood (0.45) and adulthood (0.80), we show substantial genetic correlation (r g = 0.89, LD score regression P = 5.4 × 10 -29 ). These findings provide new insight into the genetic architecture of intelligence.

  5. Ion channeling

    International Nuclear Information System (INIS)

    Erramli, H.; Blondiaux, G.

    1994-01-01

    Channeling phenomenon was predicted, many years ago, by stark. The first channeling experiments were performed in 1963 by Davies and his coworkers. Parallely Robinson and Oen have investigated this process by simulating trajectories of ions in monocrystals. This technique has been combined with many methods like Rutherford Backscattering Spectrometry (R.B.S.), Particles Induced X-rays Emission (P.I.X.E) and online Nuclear Reaction (N.R.A.) to localize trace elements in the crystal or to determine crystalline quality. To use channeling for material characterization we need data about the stopping power of the incident particle in the channeled direction. The ratios of channeled to random stopping powers of silicon for irradiation in the direction have been investigated and compared to the available theoretical results. We describe few applications of ion channeling in the field of materials characterization. Special attention is given to ion channeling combined with Charged Particle Activation Analysis (C.P.A.A.) for studying the behaviour of oxygen atoms in Czochralski silicon lattices under the influence of internal gettering and in different gaseous atmospheres. Association between ion channeling and C.P.A.A was also utilised for studying the influence of the growing conditions on concentration and position of carbon atoms at trace levels in the MOVPE Ga sub (1-x) Al sub x lattice. 6 figs., 1 tab., 32 refs. (author)

  6. Channel characteristics and coordination in three-echelon dual-channel supply chain

    Science.gov (United States)

    Saha, Subrata

    2016-02-01

    We explore the impact of channel structure on the manufacturer, the distributer, the retailer and the entire supply chain by considering three different channel structures in radiance of with and without coordination. These structures include a traditional retail channel and two manufacturer direct channels with and without consistent pricing. By comparing the performance of the manufacturer, the distributer and the retailer, and the entire supply chain in three different supply chain structures, it is established analytically that, under some conditions, a dual channel can outperform a single retail channel; as a consequence, a coordination mechanism is developed that not only coordinates the dual channel but also outperforms the non-cooperative single retail channel. All the analytical results are further analysed through numerical examples.

  7. Synergistic Malaria Parasite Killing by Two Types of Plasmodial Surface Anion Channel Inhibitors.

    Directory of Open Access Journals (Sweden)

    Margaret Pain

    Full Text Available Malaria parasites increase their host erythrocyte's permeability to a broad range of ions and organic solutes. The plasmodial surface anion channel (PSAC mediates this uptake and is an established drug target. Development of therapies targeting this channel is limited by several problems including interactions between known inhibitors and permeating solutes that lead to incomplete channel block. Here, we designed and executed a high-throughput screen to identify a novel class of PSAC inhibitors that overcome this solute-inhibitor interaction. These new inhibitors differ from existing blockers and have distinct effects on channel-mediated transport, supporting a model of two separate routes for solute permeation though PSAC. Combinations of inhibitors specific for the two routes had strong synergistic action against in vitro parasite propagation, whereas combinations acting on a single route produced only additive effects. The magnitude of synergism depended on external nutrient concentrations, consistent with an essential role of the channel in parasite nutrient acquisition. The identified inhibitors will enable a better understanding of the channel's structure-function and may be starting points for novel combination therapies that produce synergistic parasite killing.

  8. A Finite Element Solution of Lateral Periodic Poisson–Boltzmann Model for Membrane Channel Proteins

    Science.gov (United States)

    Xu, Jingjie; Lu, Benzhuo

    2018-01-01

    Membrane channel proteins control the diffusion of ions across biological membranes. They are closely related to the processes of various organizational mechanisms, such as: cardiac impulse, muscle contraction and hormone secretion. Introducing a membrane region into implicit solvation models extends the ability of the Poisson–Boltzmann (PB) equation to handle membrane proteins. The use of lateral periodic boundary conditions can properly simulate the discrete distribution of membrane proteins on the membrane plane and avoid boundary effects, which are caused by the finite box size in the traditional PB calculations. In this work, we: (1) develop a first finite element solver (FEPB) to solve the PB equation with a two-dimensional periodicity for membrane channel proteins, with different numerical treatments of the singular charges distributions in the channel protein; (2) add the membrane as a dielectric slab in the PB model, and use an improved mesh construction method to automatically identify the membrane channel/pore region even with a tilt angle relative to the z-axis; and (3) add a non-polar solvation energy term to complete the estimation of the total solvation energy of a membrane protein. A mesh resolution of about 0.25 Å (cubic grid space)/0.36 Å (tetrahedron edge length) is found to be most accurate in linear finite element calculation of the PB solvation energy. Computational studies are performed on a few exemplary molecules. The results indicate that all factors, the membrane thickness, the length of periodic box, membrane dielectric constant, pore region dielectric constant, and ionic strength, have individually considerable influence on the solvation energy of a channel protein. This demonstrates the necessity to treat all of those effects in the PB model for membrane protein simulations. PMID:29495644

  9. Planar Superconducting Millimeter-Wave/Terahertz Channelizing Filter

    Science.gov (United States)

    Ehsan, Negar; U-yen, Kongpop; Brown, Ari; Hsieh, Wen-Ting; Wollack, Edward; Moseley, Samuel

    2013-01-01

    This innovation is a compact, superconducting, channelizing bandpass filter on a single-crystal (0.45 m thick) silicon substrate, which operates from 300 to 600 GHz. This device consists of four channels with center frequencies of 310, 380, 460, and 550 GHz, with approximately 50-GHz bandwidth per channel. The filter concept is inspired by the mammalian cochlea, which is a channelizing filter that covers three decades of bandwidth and 3,000 channels in a very small physical space. By using a simplified physical cochlear model, and its electrical analog of a channelizing filter covering multiple octaves bandwidth, a large number of output channels with high inter-channel isolation and high-order upper stopband response can be designed. A channelizing filter is a critical component used in spectrometer instruments that measure the intensity of light at various frequencies. This embodiment was designed for MicroSpec in order to increase the resolution of the instrument (with four channels, the resolution will be increased by a factor of four). MicroSpec is a revolutionary wafer-scale spectrometer that is intended for the SPICA (Space Infrared Telescope for Cosmology and Astrophysics) Mission. In addition to being a vital component of MicroSpec, the channelizing filter itself is a low-resolution spectrometer when integrated with only an antenna at its input, and a detector at each channel s output. During the design process for this filter, the available characteristic impedances, possible lumped element ranges, and fabrication tolerances were identified for design on a very thin silicon substrate. Iterations between full-wave and lumped-element circuit simulations were performed. Each channel s circuit was designed based on the availability of characteristic impedances and lumped element ranges. This design was based on a tabular type bandpass filter with no spurious harmonic response. Extensive electromagnetic modeling for each channel was performed. Four channels

  10. TASK Channels on Basal Forebrain Cholinergic Neurons Modulate Electrocortical Signatures of Arousal by Histamine.

    Science.gov (United States)

    Vu, Michael T; Du, Guizhi; Bayliss, Douglas A; Horner, Richard L

    2015-10-07

    Basal forebrain cholinergic neurons are the main source of cortical acetylcholine, and their activation by histamine elicits cortical arousal. TWIK-like acid-sensitive K(+) (TASK) channels modulate neuronal excitability and are expressed on basal forebrain cholinergic neurons, but the role of TASK channels in the histamine-basal forebrain cholinergic arousal circuit is unknown. We first expressed TASK channel subunits and histamine Type 1 receptors in HEK cells. Application of histamine in vitro inhibited the acid-sensitive K(+) current, indicating a functionally coupled signaling mechanism. We then studied the role of TASK channels in modulating electrocortical activity in vivo using freely behaving wild-type (n = 12) and ChAT-Cre:TASK(f/f) mice (n = 12), the latter lacking TASK-1/3 channels on cholinergic neurons. TASK channel deletion on cholinergic neurons significantly altered endogenous electroencephalogram oscillations in multiple frequency bands. We then identified the effect of TASK channel deletion during microperfusion of histamine into the basal forebrain. In non-rapid eye movement sleep, TASK channel deletion on cholinergic neurons significantly attenuated the histamine-induced increase in 30-50 Hz activity, consistent with TASK channels contributing to histamine action on basal forebrain cholinergic neurons. In contrast, during active wakefulness, histamine significantly increased 30-50 Hz activity in ChAT-Cre:TASK(f/f) mice but not wild-type mice, showing that the histamine response depended upon the prevailing cortical arousal state. In summary, we identify TASK channel modulation in response to histamine receptor activation in vitro, as well as a role of TASK channels on cholinergic neurons in modulating endogenous oscillations in the electroencephalogram and the electrocortical response to histamine at the basal forebrain in vivo. Attentive states and cognitive function are associated with the generation of γ EEG activity. Basal forebrain

  11. The least channel capacity for chaos synchronization.

    Science.gov (United States)

    Wang, Mogei; Wang, Xingyuan; Liu, Zhenzhen; Zhang, Huaguang

    2011-03-01

    Recently researchers have found that a channel with capacity exceeding the Kolmogorov-Sinai entropy of the drive system (h(KS)) is theoretically necessary and sufficient to sustain the unidirectional synchronization to arbitrarily high precision. In this study, we use symbolic dynamics and the automaton reset sequence to distinguish the information that is required in identifying the current drive word and obtaining the synchronization. Then, we show that the least channel capacity that is sufficient to transmit the distinguished information and attain the synchronization of arbitrarily high precision is h(KS). Numerical simulations provide support for our conclusions.

  12. Molecular Basis of Paraltyic Neurotoxin Action on Voltage-Sensitive Sodium Channels

    Science.gov (United States)

    1985-10-14

    of 9,700 daltons isolated from the coral Goni2oora gy. (1). The toxin enhances neurally mediated contraction of blood vessels and taenia coli of the...sites on the solium channel and to identify the site of GPT action within the structure of the sodium channel protein. 2. Site of Action of Brvyetoxin

  13. A negative charge in transmembrane segment 1 of domain II of the cockroach sodium channel is critical for channel gating and action of pyrethroid insecticides

    International Nuclear Information System (INIS)

    Du Yuzhe; Song Weizhong; Groome, James R.; Nomura, Yoshiko; Luo Ningguang; Dong Ke

    2010-01-01

    Voltage-gated sodium channels are the primary target of pyrethroids, an important class of synthetic insecticides. Pyrethroids bind to a distinct receptor site on sodium channels and prolong the open state by inhibiting channel deactivation and inactivation. Recent studies have begun to reveal sodium channel residues important for pyrethroid binding. However, how pyrethroid binding leads to inhibition of sodium channel deactivation and inactivation remains elusive. In this study, we show that a negatively charged aspartic acid residue at position 802 (D802) located in the extracellular end of transmembrane segment 1 of domain II (IIS1) is critical for both the action of pyrethroids and the voltage dependence of channel activation. Charge-reversing or -neutralizing substitutions (K, G, or A) of D802 shifted the voltage dependence of activation in the depolarizing direction and reduced channel sensitivity to deltamethrin, a pyrethroid insecticide. The charge-reversing mutation D802K also accelerated open-state deactivation, which may have counteracted the inhibition of sodium channel deactivation by deltamethrin. In contrast, the D802G substitution slowed open-state deactivation, suggesting an additional mechanism for neutralizing the action of deltamethrin. Importantly, Schild analysis showed that D802 is not involved in pyrethroid binding. Thus, we have identified a sodium channel residue that is critical for regulating the action of pyrethroids on the sodium channel without affecting the receptor site of pyrethroids.

  14. Channel stability of Turkey Creek, Nebraska

    Science.gov (United States)

    Rus, David L.; Soenksen, Philip J.

    1998-01-01

    Channelization on Turkey Creek and its receiving stream, the South Fork Big Nemaha River, has disturbed the equilibrium of Turkey Creek and has led to channel-stability problems, such as degradation and channel widening, which pose a threat to bridges and land adjacent to the stream. As part of a multiagency study, the U.S. Geological Survey assessed channel stability at two bridge sites on upper and middle portions of Turkey Creek by analyzing streambed-elevation data for gradation changes, comparing recent cross-section surveys and historic accounts, identifying bank-failure blocks, and analyzing tree-ring samples. These results were compared to gradation data and trend results for a U.S. Geological Survey streamflow-gaging station near the mouth of Turkey Creek from a previous study. Examination of data on streambed elevations reveals that degradation has occurred. The streambed elevation declined 0.5 m at the upper site from 1967-97. The streambed elevation declined by 3.2 m at the middle site from 1948-97 and exposed 2 m of the pilings of the Nebraska Highway 8 bridge. Channel widening could not be verified at the two sites from 1967-97, but a historic account indicates widening at the middle site to be two to three times that of the 1949 channel width. Small bank failures were evident at the upper site and a 4-m-wide bank failure occurred at the middle site in 1987 according to tree ring analyses. Examination of streambed-elevation data from a previous study at the lower site reveals a statistically significant aggrading trend from 1958-93. Further examination of these data suggests minor degradation occurred until 1975, followed by aggradation.

  15. Influence of large wood on channel morphology and sediment storage in headwater mountain streams, Fraser Experimental Forest, Colorado

    Science.gov (United States)

    Sandra E. Ryan; Erica L. Bishop; J. Michael Daniels

    2014-01-01

    Large fallen wood can have a significant impact on channel form and process in forested mountain streams. In this study, four small channels on the Fraser Experimental Forest near Fraser, Colorado, USA, were surveyed for channel geometries and large wood loading, including the size, source, and characteristics of individual pieces. The study is part of a larger effort...

  16. FMRFamide-gated sodium channel and ASIC channels: a new class of ionotropic receptors for FMRFamide and related peptides.

    Science.gov (United States)

    Lingueglia, Eric; Deval, Emmanuel; Lazdunski, Michel

    2006-05-01

    FMRFamide and related peptides typically exert their action through G-protein coupled receptors. However, two ionotropic receptors for these peptides have recently been identified. They are both members of the epithelial amiloride-sensitive Na+ channel and degenerin (ENaC/DEG) family of ion channels. The invertebrate FMRFamide-gated Na+ channel (FaNaC) is a neuronal Na+-selective channel which is directly gated by micromolar concentrations of FMRFamide and related tetrapeptides. Its response is fast and partially desensitizing, and FaNaC has been proposed to participate in peptidergic neurotransmission. On the other hand, mammalian acid-sensing ion channels (ASICs) are not gated but are directly modulated by FMRFamide and related mammalian peptides like NPFF and NPSF. ASICs are activated by external protons and are therefore extracellular pH sensors. They are expressed both in the central and peripheral nervous system and appear to be involved in many physiological and pathophysiological processes such as hippocampal long-term potentiation and defects in learning and memory, acquired fear-related behavior, retinal function, brain ischemia, pain sensation in ischemia and inflammation, taste perception, hearing functions, and mechanoperception. The potentiation of ASIC activity by endogenous RFamide neuropeptides probably participates in the response to noxious acidosis in sensory and central neurons. Available data also raises the possibility of the existence of still unknown FMRFamide related endogenous peptides acting as direct agonists for ASICs.

  17. MONETARY TRANSMISSION CHANNELS IN ROMANIA – THE CREDIT CHANNEL

    Directory of Open Access Journals (Sweden)

    Magdalena RĂDULESCU

    2009-12-01

    Full Text Available The theoretical – intuitive analysis applied to the segment of monetary transmission evidences the fact that forming the traditional monetary impulses transmission channels are in a starting phase due to the long financial non – intermediary process which Romanian economy had known. In these conditions, the exchange rate channel, and also NBR currency purchases was, for a long time, an important way through which monetary authorities actions influenced macro economical behaviors. But starting with 2000, it is observed a credit channel reactivation and, especially, interest rate channel. Anyhow, the credit channel continues to be undermined by the existence of liquidity surplus within the system, by the phenomena of substitution of national currency credit with currency credits, and also moral hazardous displays. Albeit some of these phenomena also affect the interest rate channel, its role in sending monetary policy impulses is in a continuous progress. Apparently, it acts by way of nominal interest rates, their real level seeming less relevant. Once with remaking the two traditional channels, the companies and households balance is configured and consolidated, which shall potentate in the future the efficiency of the monetary policy. This paper analyses the credit channel in Romania, through an unrestricted VAR analysis.. It shows the responses of exchange rate, inflation rate, GDP, interest rate, imports and exports to a shock on non-governmental credit

  18. Investigations of Orchestra Auralizations Using the Multi-Channel Multi-Source Auralization Technique

    DEFF Research Database (Denmark)

    Vigeant, Michelle; Wang, Lily M.; Rindel, Jens Holger

    2008-01-01

    a multi-channel multi-source auralization technique, involving individual five-channel anechoic recordings of each instrumental part of two symphonies. In the first study, these auralizations were subjectively compared to orchestra auralizations made using (a) a single omni-directional source, (b......) a surface source, and (c) single-channel multi-source method. Results show that the multi-source auralizations were rated to be more realistic than the surface source ones and to have larger source width than the single omni-directional source auralizations. No significant differences were found between......Room acoustics computer modeling is a tool for generating impulse responses and auralizations from modeled spaces. The auralizations are commonly made from a single-channel anechoic recording of solo instruments. For this investigation, auralizations of an entire orchestra were created using...

  19. ZnO-channel thin-film transistors: Channel mobility

    International Nuclear Information System (INIS)

    Hoffman, R.L.

    2004-01-01

    ZnO-channel thin-film transistor (TFT) test structures are fabricated using a bottom-gate structure on thermally oxidized Si; ZnO is deposited via RF sputtering from an oxide target, with an unheated substrate. Electrical characteristics are evaluated, with particular attention given to the extraction and interpretation of transistor channel mobility. ZnO-channel TFT mobility exhibits severe deviation from that assumed by ideal TFT models; mobility extraction methodology must accordingly be recast so as to provide useful insight into device operation. Two mobility metrics, μ avg and μ inc , are developed and proposed as relevant tools in the characterization of nonideal TFTs. These mobility metrics are employed to characterize the ZnO-channel TFTs reported herein; values for μ inc as high as 25 cm2/V s are measured, comprising a substantial increase in ZnO-channel TFT mobility as compared to previously reported performance for such devices

  20. Analyzing determinants influencing an individual׳s intention to use social commerce website

    Directory of Open Access Journals (Sweden)

    Prerna Lal

    2017-06-01

    Full Text Available The evolution of social media has changed the landscape of online commerce for both organizations as well as customers. Introduction of social commerce websites has bought shift in consumers׳ buying decision, i.e. from individual to social shopping. This study aims to identify factors that influence an individual׳s decision to use social commerce websites in an Indian Context. A conceptual model was developed based on extensive literature review. Wherein total six factors that influence an individual׳s intention to use social commerce were identified and were divided into three broad categories: social factors (informational support and community commitment, trust (towards members and community and website quality (ease of use and service quality. Research model was empirically examined using structural equation modeling. The findings of this study demonstrated positive relationship between all six factors and an individual׳s intention to use social commerce website. Additionally, study identified informational support as the most significant factor that influences an individual׳s intention to use social commerce website followed by trust towards members, service equality, trust towards community, ease of navigation, and community commitment.

  1. Single molecule microscopy on Store-Operated Calcium channels

    International Nuclear Information System (INIS)

    Madl, J.

    2011-01-01

    Store-Operated Calcium Entry is essential for many signaling processes in non-excitable cells. The best studied Store-Operated Calcium current is the Calcium-Release-Activated-Calcium (CRAC) current in T-cells and mast cells, with Orai1 representing the essential pore forming subunit. Functional CRAC channels in store-depleted cells are composed of four Orai1 subunits. However, the stoichiometric composition in resting cells is still discussed controversially: both a tetrameric and a dimeric stoichiometry of resting-state Orai1 have been reported for immobilized or immobile Orai1 proteins. The aim of this thesis was to design a more versatile approach that allows reliable determination of the subunit stoichiometry of mobile Orai1 channels. The motive for this approach is that mobile sub-fractions of the entire Orai1 population provide the cleanest pool of data, devoid of contributions e.g. from immobile Orai1 clusters or Orai1-loaded vesicles attached to the plasma membrane. Moreover, resting-state Orai1 is predominantly mobile, and mobility appears critical for the lateral redistribution which occurs upon store depletion. The method per se is based on single molecule fluorescence microscopy and brightness analysis. Orai1 proteins were fused to a monomeric variant of Green Fluorescent Protein (mGFP) and over-expressed in a human cell line (T24). The 1:1 labeling stoichiometry allows using the brightness of individual Orai1-mGFP channels as a direct measure of the pore stoichiometry. Due to over-expression a potential mixing with endogenous Orai1 can be neglected. However, over-expression of Orai1-mGFP results in channel densities that are too high to allow for resolving single channels using diffraction limited optical microscopy. In order to overcome this challenge, I developed an experimental strategy that allows reduction of the density of actively fluorescent Orai1-mGFP channels without altering the labeling stoichiometry. In order to reduce the surface density

  2. Landuse Types within Channel Corridor and River Channel Morphology of River Ona, Ibadan, Nigeria

    Directory of Open Access Journals (Sweden)

    Olutoyin Fashae

    2017-12-01

    Full Text Available The importance of river a corridor warrants a well thought out and balanced management approach because it helps in improving or maintaining water quality, protecting wetlands, etc. Hence, this study seeks to identify major landuse types within the River Ona Corridor; examine the impact of these landuse types within the River Ona corridor on its channel morphology and understand the risk being posed by these landuse types. The study is designed by selecting two reaches of six times the average width from each of the four major landuse types that exist along the river corridor. This study revealed that along the downstream section of Eleyele Dam of River Ona, natural forest stabilizes river channel banks, thereby presenting a narrow and shallow width and depth respectively but the widest of all is found at the agricultural zones.

  3. Disguising quantum channels by mixing and channel distance trade-off

    International Nuclear Information System (INIS)

    Fung, Chi-Hang Fred; Chau, H F

    2014-01-01

    We consider the reverse problem of the distinguishability of two quantum channels, which we call the disguising problem. Given two quantum channels, the goal here is to make the two channels identical by mixing with some other channels with minimal mixing probabilities. This quantifies how much one channel can disguise as the other. In addition, the possibility to trade-off between the two mixing probabilities allows one channel to be more preserved (less mixed) at the expense of the other. We derive lower- and upper-bounds of the trade-off curve and apply them to a few example channels. Optimal trade-off is obtained in one example. We relate the disguising problem and the distinguishability problem by showing that the former can lower and upper bound the diamond norm. We also show that the disguising problem gives an upper-bound on the key generation rate in quantum cryptography. (paper)

  4. Application and validation of case-finding algorithms for identifying individuals with human immunodeficiency virus from administrative data in British Columbia, Canada.

    Directory of Open Access Journals (Sweden)

    Bohdan Nosyk

    Full Text Available To define a population-level cohort of individuals infected with the human immunodeficiency virus (HIV in the province of British Columbia from available registries and administrative datasets using a validated case-finding algorithm.Individuals were identified for possible cohort inclusion from the BC Centre for Excellence in HIV/AIDS (CfE drug treatment program (antiretroviral therapy and laboratory testing datasets (plasma viral load (pVL and CD4 diagnostic test results, the BC Centre for Disease Control (CDC provincial HIV surveillance database (positive HIV tests, as well as databases held by the BC Ministry of Health (MoH; the Discharge Abstract Database (hospitalizations, the Medical Services Plan (physician billing and PharmaNet databases (additional HIV-related medications. A validated case-finding algorithm was applied to distinguish true HIV cases from those likely to have been misclassified. The sensitivity of the algorithms was assessed as the proportion of confirmed cases (those with records in the CfE, CDC and MoH databases positively identified by each algorithm. A priori hypotheses were generated and tested to verify excluded cases.A total of 25,673 individuals were identified as having at least one HIV-related health record. Among 9,454 unconfirmed cases, the selected case-finding algorithm identified 849 individuals believed to be HIV-positive. The sensitivity of this algorithm among confirmed cases was 88%. Those excluded from the cohort were more likely to be female (44.4% vs. 22.5%; p<0.01, had a lower mortality rate (2.18 per 100 person years (100PY vs. 3.14/100PY; p<0.01, and had lower median rates of health service utilization (days of medications dispensed: 9745/100PY vs. 10266/100PY; p<0.01; days of inpatient care: 29/100PY vs. 98/100PY; p<0.01; physician billings: 602/100PY vs. 2,056/100PY; p<0.01.The application of validated case-finding algorithms and subsequent hypothesis testing provided a strong framework for

  5. Individuals with knee impairments identify items in need of clarification in the Patient Reported Outcomes Measurement Information System (PROMIS®) pain interference and physical function item banks - a qualitative study.

    Science.gov (United States)

    Lynch, Andrew D; Dodds, Nathan E; Yu, Lan; Pilkonis, Paul A; Irrgang, James J

    2016-05-11

    The content and wording of the Patient Reported Outcome Measurement Information System (PROMIS) Physical Function and Pain Interference item banks have not been qualitatively assessed by individuals with knee joint impairments. The purpose of this investigation was to identify items in the PROMIS Physical Function and Pain Interference Item Banks that are irrelevant, unclear, or otherwise difficult to respond to for individuals with impairment of the knee and to suggest modifications based on cognitive interviews. Twenty-nine individuals with knee joint impairments qualitatively assessed items in the Pain Interference and Physical Function Item Banks in a mixed-methods cognitive interview. Field notes were analyzed to identify themes and frequency counts were calculated to identify items not relevant to individuals with knee joint impairments. Issues with clarity were identified in 23 items in the Physical Function Item Bank, resulting in the creation of 43 new or modified items, typically changing words within the item to be clearer. Interpretation issues included whether or not the knee joint played a significant role in overall health and age/gender differences in items. One quarter of the original items (31 of 124) in the Physical Function Item Bank were identified as irrelevant to the knee joint. All 41 items in the Pain Interference Item Bank were identified as clear, although individuals without significant pain substituted other symptoms which interfered with their life. The Physical Function Item Bank would benefit from additional items that are relevant to individuals with knee joint impairments and, by extension, to other lower extremity impairments. Several issues in clarity were identified that are likely to be present in other patient cohorts as well.

  6. A Tour de Force: The Discovery, Properties, and Function of Piezo Channels.

    Science.gov (United States)

    Gottlieb, P A

    2017-01-01

    Mechanical transducers appear throughout cell biology and are used to convert mechanical stress into chemical or electrical signals that allow the cell to respond to environmental changes. In the past six years, a eukaryotic mechanical channel family with two members, Piezo1 and Piezo2, has been identified. Piezo1 was shown to be a cation-selective channel that does not require ancillary proteins for activity. Mouse Piezo1 is large, with over 2500 amino acids, and is not homologous to other ion channels. Both piezo channels have rapid voltage-dependent inactivation with a reversal potential near 0mV. The CryoEm structure of Piezo1 at 4.8Å shows trimer stoichiometry. Since the discovery of the piezo channels, their roles in the physiological response of cells have started to emerge. Significant progress has been made in understanding the intrinsic properties of the channels and how these properties are modulated by cytoskeletal elements. Specific diseases, such as hereditary xerocytosis affecting red blood cells, have mutations in Piezo1 that alter the cell's response to force, typically slowing inactivation and introducing a latency for activation. A number of physiological functions for piezo channels have been identified. These range from sensing the stiffness of surrounding substrate, to the response to light touch, to serotonin release from the gut. This review provides a general overview of the properties and roles of Piezo1 and Piezo2 in eukaryotic mechanotransduction. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Verification of otolith identity used by fisheries scientists for aging channel catfish

    Science.gov (United States)

    Long, James M.; Stewart, David R.

    2010-01-01

    Previously published studies of the age estimation of channel catfish Ictalurus punctatus based on otoliths have reported using the sagittae, whereas it is likely they were actually using the lapilli. This confusion may have resulted because in catfishes (ostariophyseans) the lapilli are the largest of the three otoliths, whereas in nonostariophysean fish the sagittae are the largest. Based on (1) scanning electron microscope microphotographs of channel catfish otoliths, (2) X-ray computed tomography scans of a channel catfish head, (3) descriptions of techniques used to removed otoliths from channel catfish reported in the literature, and (4) a sample of channel catfish otoliths received from fisheries biologists from around the country, it is clear that lapilli are most often used for channel catfish aging studies, not sagittae, as has been previously reported. Fisheries scientists who obtain otoliths from channel catfish can use the information in this paper to correctly identify otolith age.

  8. Spatio-temporal scaling of channels in braided streams.

    Science.gov (United States)

    A.G. Hunt; G.E. Grant; V.K. Gupta

    2006-01-01

    The spatio-temporal scaling relationship for individual channels in braided streams is shown to be identical to the spatio-temporal scaling associated with constant Froude number, e.g., Fr = l. A means to derive this relationship is developed from a new theory of sediment transport. The mechanism by which the Fr = l condition apparently governs the scaling seems to...

  9. Decreased expression of Kv7 channels in Hirchsprung's disease.

    Science.gov (United States)

    O'Donnell, Anne-Marie; Coyle, David; Puri, Prem

    2017-07-01

    Voltage-dependent K + channels (Kv channels) participate in electrical rhythmicity and smooth muscle responses and are regulated by excitatory and inhibitory neurotransmitters. Kv channels also participate in the interstitial cell of Cajal (ICC) and smooth muscle cell (SMC) responses to neural inputs. The Kv family consists of 12 subfamilies, Kv1-Kv12, with five members of the Kv7 family identified to date: Kv7.1-Kv7.5. A recent study identified the potassium channel Kv7.5 as having a role in the excitability of ICC-IM in the mouse colon. We therefore designed this study to test the hypothesis that Kv7 channels are present in the normal human colon and are reduced in Hirschprung's disease (HSCR). HSCR tissue specimens were collected at the time of pull-through surgery (n=10), while normal control tissue specimens were obtained at the time of colostomy closure in patients with imperforate anus (n=10). Kv7.3-Kv7.5 immunohistochemistry was performed and visualized using confocal microscopy to assess their distribution. Western blot analysis was undertaken to determine Kv7.3-Kv7.5 protein quantification. Kv7.3 and Kv7.4-immunoreactivity was co-localized with neuron and ICC markers, while Kv7.5 was found to be expressed on both ICCs and SMCs. Western blot analysis revealed similar levels of Kv7.3 and Kv7.5 expression in the normal colon and HSCR colon, while Kv7.4 proteins were found to be markedly decreased in ganglionic specimens and decreased further in aganglionic specimens. A deficiency of Kv7.4 channels in the ganglionic and aganglionic bowel may place a role in colonic dysmotility in HSCR. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Multi-channel service concept design and prototyping

    NARCIS (Netherlands)

    Sperling, C.P.; Simons, L.P.A.; Bouwman, W.A.G.A.

    2007-01-01

    Designing e-services which have to function in a multi-channel context has proved to be challenging for organizations. Previous research has shown that structured design methods are useful to structure the design process. In this paper we proceed from an existing method (which identifies

  11. Compound Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Kramer Gerhard

    2009-01-01

    Full Text Available Abstract This paper considers the compound wiretap channel, which generalizes Wyner's wiretap model to allow the channels to the (legitimate receiver and to the eavesdropper to take a number of possible states. No matter which states occur, the transmitter guarantees that the receiver decodes its message and that the eavesdropper is kept in full ignorance about the message. The compound wiretap channel can also be viewed as a multicast channel with multiple eavesdroppers, in which the transmitter sends information to all receivers and keeps the information secret from all eavesdroppers. For the discrete memoryless channel, lower and upper bounds on the secrecy capacity are derived. The secrecy capacity is established for the degraded channel and the semideterministic channel with one receiver. The parallel Gaussian channel is further studied. The secrecy capacity and the secrecy degree of freedom ( are derived for the degraded case with one receiver. Schemes to achieve the for the case with two receivers and two eavesdroppers are constructed to demonstrate the necessity of a prefix channel in encoder design. Finally, the multi-antenna (i.e., MIMO compound wiretap channel is studied. The secrecy capacity is established for the degraded case and an achievable is given for the general case.

  12. ATP Release Channels

    Directory of Open Access Journals (Sweden)

    Akiyuki Taruno

    2018-03-01

    Full Text Available Adenosine triphosphate (ATP has been well established as an important extracellular ligand of autocrine signaling, intercellular communication, and neurotransmission with numerous physiological and pathophysiological roles. In addition to the classical exocytosis, non-vesicular mechanisms of cellular ATP release have been demonstrated in many cell types. Although large and negatively charged ATP molecules cannot diffuse across the lipid bilayer of the plasma membrane, conductive ATP release from the cytosol into the extracellular space is possible through ATP-permeable channels. Such channels must possess two minimum qualifications for ATP permeation: anion permeability and a large ion-conducting pore. Currently, five groups of channels are acknowledged as ATP-release channels: connexin hemichannels, pannexin 1, calcium homeostasis modulator 1 (CALHM1, volume-regulated anion channels (VRACs, also known as volume-sensitive outwardly rectifying (VSOR anion channels, and maxi-anion channels (MACs. Recently, major breakthroughs have been made in the field by molecular identification of CALHM1 as the action potential-dependent ATP-release channel in taste bud cells, LRRC8s as components of VRACs, and SLCO2A1 as a core subunit of MACs. Here, the function and physiological roles of these five groups of ATP-release channels are summarized, along with a discussion on the future implications of understanding these channels.

  13. Functional characterization of a prokaryotic Kir channel.

    Science.gov (United States)

    Enkvetchakul, Decha; Bhattacharyya, Jaya; Jeliazkova, Iana; Groesbeck, Darcy K; Cukras, Catherine A; Nichols, Colin G

    2004-11-05

    The Kir gene family encodes inward rectifying K+ (Kir) channels that are widespread and critical regulators of excitability in eukaryotic cells. A related gene family (KirBac) has recently been identified in prokaryotes. While a crystal structure of one member, Kir-Bac1.1, has been solved, there has been no functional characterization of any KirBac gene products. Here we present functional characterization of KirBac1.1 reconstituted in liposomes. Utilizing a 86Rb+ uptake assay, we demonstrate that KirBac1.1 generates a K+ -selective permeation path that is inhibited by extraliposomal Ba2+ and Ca2+ ions. In contrast to KcsA (an acid-activated bacterial potassium channel), KirBac1.1 is inhibited by extraliposomal acid (pKa approximately 6). This characterization of KirBac1.1 activity now paves the way for further correlation of structure and function in this model Kir channel.

  14. Spark Channels

    Energy Technology Data Exchange (ETDEWEB)

    Haydon, S. C. [Department of Physics, University of New England, Armidale, NSW (Australia)

    1968-04-15

    A brief summary is given of the principal methods used for initiating spark channels and the various highly time-resolved techniques developed recently for studies with nanosecond resolution. The importance of the percentage overvoltage in determining the early history and subsequent development of the various phases of the growth of the spark channel is discussed. An account is then given of the recent photographic, oscillographic and spectroscopic investigations of spark channels initiated by co-axial cable discharges of spark gaps at low [{approx} 1%] overvoltages. The phenomena observed in the development of the immediate post-breakdown phase, the diffuse glow structure, the growth of the luminous filament and the final formation of the spark channel in hydrogen are described. A brief account is also given of the salient features emerging from corresponding studies of highly overvolted spark gaps in which the spark channel develops from single avalanche conditions. The essential differences between the two types of channel formation are summarized and possible explanations of the general features are indicated. (author)

  15. Adaptive evolution of the vertebrate skeletal muscle sodium channel

    Directory of Open Access Journals (Sweden)

    Jian Lu

    2011-01-01

    Full Text Available Tetrodotoxin (TTX is a highly potent neurotoxin that blocks the action potential by selectively binding to voltage-gated sodium channels (Na v. The skeletal muscle Na v (Na v1.4 channels in most pufferfish species and certain North American garter snakes are resistant to TTX, whereas in most mammals they are TTX-sensitive. It still remains unclear as to whether the difference in this sensitivity among the various vertebrate species can be associated with adaptive evolution. In this study, we investigated the adaptive evolution of the vertebrate Na v1.4 channels. By means of the CODEML program of the PAML 4.3 package, the lineages of both garter snakes and pufferfishes were denoted to be under positive selection. The positively selected sites identified in the p-loop regions indicated their involvement in Na v1.4 channel sensitivity to TTX. Most of these sites were located in the intracellular regions of the Na v1.4 channel, thereby implying the possible association of these regions with the regulation of voltage-sensor movement.

  16. Clinical Application of Colour Modulation of Gamma Energy and Depth by Dual-Channel Scanning

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, E.; Ben-Porath, M. [Veterans Administration Hospital, Hines, IL (United States)

    1969-01-15

    A dual-channel scanning system has been described permitting the simultaneous imaging in individual color of the distribution of two gamma-emitting radioisotopes. In those cases where two organs are adjacent and concentrate the same isotope, they may be displayed in separate color if one of the organs concentrates another gamma-emitting isotope with a different energy. This is accomplished by individual color readout of this isotope and the display of the subtraction of this isotope from the common isotope in another color. By using two facing scintillation probes on either side of the individual being scanned, two overlapping organs at different depths concentrating the same isotope can be color differentiated by a dual-channel playout of each probe. The principal application of these dual-channel scanning methods to date has been the simultaneous display of the liver and pancreas in individual colors using {sup 198}Au and {sup 75}selenomethionine. Characteristic scans have been obtained which differentiate a number of disease states from the normal pancreas and liver. The pancreatic and liver diseases studied and characterized are carcinoma of the pancreas, pancreatic insufficiency, acute recurrent pancreatitis, pancreatic pseudocyst and Laennec's cirrhosis, hepatoma and metastatic malignancy in the liver. The uptake of {sup 75}selenomethionine in malignant lesions in many instances produces positive scans of these tumors in contrasting color to the liver. Depth discrimination in color with the two-probe system has permitted the lateralization of intracranial lesions, the color of the display being proportional to the depth of the lesion. The discrimination of depth and gamma-ray energy by dual-channel color scanning and its general application in visualizing other organs has been accomplished. (author)

  17. An investigation of 'sparse channel networks'. Characteristic behaviours and their causes

    Energy Technology Data Exchange (ETDEWEB)

    Black, J.H. (In Situ Solutions, East Bridgford (GB)); Barker, J.A.; Woodman, N.D. (Univ. of Southampton (GB))

    2007-09-15

    This report represents a third study in a series concerned with groundwater flow in poorly permeable fractured crystalline rocks. The study has brought together three linked, but distinct, elements; a mathematical analysis of the intersection of ellipses, a review of field measurements associated with nuclear waste repository investigations and probabilistic simulations using a lattice network numerical model. We conclude that the model of channels that traverse fracture intersections without necessarily branching is a very likely representation of reality. More generally, assembling all the lines of evidence, it is suggested that groundwater flow systems in fractured crystalline rocks in the environs of underground laboratories have the following characteristics: Groundwater flows within a sparse network of channels just above the percolation limit. The frequency of intersections is low in that individual channels extend considerable distances between significant junctions. Individual channels often extend over many fracture surfaces and the resulting flow system is only weakly related to the density or size of mappable fractures. The sparseness of systems compared to the size of drifts and tunnels means that only a very few flow channels are intersected by drifts and tunnels. Highly convergent flow is required to connect to the rest of the network and this is misinterpreted as a skin of low hydraulic conductivity. Systems are so sparse that they are controlled by a few 'chokes' that give rise to compartments of head, and probably, of groundwater chemistry. Channels occur on all fracture planes, including those within fracture zones, and although the characteristics of the fracture zone channel networks may differ from those in surrounding rocks, they are nonetheless still channel networks. The actively flowing sparse channel network, occurring within any particular rock, is a naturally selected, small sub-set of the available channels. Hence, there are

  18. Joint source/channel coding of scalable video over noisy channels

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, G.; Zakhor, A. [Department of Electrical Engineering and Computer Sciences University of California Berkeley, California94720 (United States)

    1997-01-01

    We propose an optimal bit allocation strategy for a joint source/channel video codec over noisy channel when the channel state is assumed to be known. Our approach is to partition source and channel coding bits in such a way that the expected distortion is minimized. The particular source coding algorithm we use is rate scalable and is based on 3D subband coding with multi-rate quantization. We show that using this strategy, transmission of video over very noisy channels still renders acceptable visual quality, and outperforms schemes that use equal error protection only. The flexibility of the algorithm also permits the bit allocation to be selected optimally when the channel state is in the form of a probability distribution instead of a deterministic state. {copyright} {ital 1997 American Institute of Physics.}

  19. Nonverbal channel use in communication of emotion: how may depend on why.

    Science.gov (United States)

    App, Betsy; McIntosh, Daniel N; Reed, Catherine L; Hertenstein, Matthew J

    2011-06-01

    This study investigated the hypothesis that different emotions are most effectively conveyed through specific, nonverbal channels of communication: body, face, and touch. Experiment 1 assessed the production of emotion displays. Participants generated nonverbal displays of 11 emotions, with and without channel restrictions. For both actual production and stated preferences, participants favored the body for embarrassment, guilt, pride, and shame; the face for anger, disgust, fear, happiness, and sadness; and touch for love and sympathy. When restricted to a single channel, participants were most confident about their communication when production was limited to the emotion's preferred channel. Experiment 2 examined the reception or identification of emotion displays. Participants viewed videos of emotions communicated in unrestricted and restricted conditions and identified the communicated emotions. Emotion identification in restricted conditions was most accurate when participants viewed emotions displayed via the emotion's preferred channel. This study provides converging evidence that some emotions are communicated predominantly through different nonverbal channels. Further analysis of these channel-emotion correspondences suggests that the social function of an emotion predicts its primary channel: The body channel promotes social-status emotions, the face channel supports survival emotions, and touch supports intimate emotions.

  20. Tuning the ion selectivity of two-pore channels

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiangtao; Zeng, Weizhong; Jiang, Youxing (UTSMC)

    2017-01-17

    Organellar two-pore channels (TPCs) contain two copies of a Shaker-like six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in plants and animals. Interestingly, plant and animal TPCs share high sequence similarity in the filter region, yet exhibit drastically different ion selectivity. Plant TPC1 functions as a nonselective cation channel on the vacuole membrane, whereas mammalian TPC channels have been shown to be endo/lysosomal Na+-selective or Ca2+-release channels. In this study, we performed systematic characterization of the ion selectivity of TPC1 from Arabidopsis thaliana (AtTPC1) and compared its selectivity with the selectivity of human TPC2 (HsTPC2). We demonstrate that AtTPC1 is selective for Ca2+ over Na+, but nonselective among monovalent cations (Li+, Na+, and K+). Our results also confirm that HsTPC2 is a Na+-selective channel activated by phosphatidylinositol 3,5-bisphosphate. Guided by our recent structure of AtTPC1, we converted AtTPC1 to a Na+-selective channel by mimicking the selectivity filter of HsTPC2 and identified key residues in the TPC filters that differentiate the selectivity between AtTPC1 and HsTPC2. Furthermore, the structure of the Na+-selective AtTPC1 mutant elucidates the structural basis for Na+ selectivity in mammalian TPCs.

  1. SK2 channels regulate mitochondrial respiration and mitochondrial Ca2+ uptake.

    Science.gov (United States)

    Honrath, Birgit; Matschke, Lina; Meyer, Tammo; Magerhans, Lena; Perocchi, Fabiana; Ganjam, Goutham K; Zischka, Hans; Krasel, Cornelius; Gerding, Albert; Bakker, Barbara M; Bünemann, Moritz; Strack, Stefan; Decher, Niels; Culmsee, Carsten; Dolga, Amalia M

    2017-05-01

    Mitochondrial calcium ([Ca 2+ ] m ) overload and changes in mitochondrial metabolism are key players in neuronal death. Small conductance calcium-activated potassium (SK) channels provide protection in different paradigms of neuronal cell death. Recently, SK channels were identified at the inner mitochondrial membrane, however, their particular role in the observed neuroprotection remains unclear. Here, we show a potential neuroprotective mechanism that involves attenuation of [Ca 2+ ] m uptake upon SK channel activation as detected by time lapse mitochondrial Ca 2+ measurements with the Ca 2+ -binding mitochondria-targeted aequorin and FRET-based [Ca 2+ ] m probes. High-resolution respirometry revealed a reduction in mitochondrial respiration and complex I activity upon pharmacological activation and overexpression of mitochondrial SK2 channels resulting in reduced mitochondrial ROS formation. Overexpression of mitochondria-targeted SK2 channels enhanced mitochondrial resilience against neuronal death, and this effect was inhibited by overexpression of a mitochondria-targeted dominant-negative SK2 channel. These findings suggest that SK channels provide neuroprotection by reducing [Ca 2+ ] m uptake and mitochondrial respiration in conditions, where sustained mitochondrial damage determines progressive neuronal death.

  2. ZAP: a distributed channel assignment algorithm for cognitive radio networks

    OpenAIRE

    Junior , Paulo Roberto ,; Fonseca , Mauro; Munaretto , Anelise; Viana , Aline ,; Ziviani , Artur

    2011-01-01

    Abstract We propose ZAP, an algorithm for the distributed channel assignment in cognitive radio (CR) networks. CRs are capable of identifying underutilized licensed bands of the spectrum, allowing their reuse by secondary users without interfering with primary users. In this context, efficient channel assignment is challenging as ideally it must be simple, incur acceptable communication overhead, provide timely response, and be adaptive to accommodate frequent changes in the network. Another ...

  3. A protein interaction mechanism for suppressing the mechanosensitive Piezo channels

    OpenAIRE

    Zhang, Tingxin; Chi, Shaopeng; Jiang, Fan; Zhao, Qiancheng; Xiao, Bailong

    2017-01-01

    Piezo proteins are bona fide mammalian mechanotransduction channels for various cell types including endothelial cells. The mouse Piezo1 of 2547 residues forms a three-bladed, propeller-like homo-trimer comprising a central pore-module and three propeller-structures that might serve as mechanotransduction-modules. However, the mechanogating and regulation of Piezo channels remain unclear. Here we identify the sarcoplasmic /endoplasmic-reticulum Ca2+ ATPase (SERCA), including the widely expres...

  4. Compound Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Shlomo Shamai (Shitz

    2009-01-01

    Full Text Available This paper considers the compound wiretap channel, which generalizes Wyner's wiretap model to allow the channels to the (legitimate receiver and to the eavesdropper to take a number of possible states. No matter which states occur, the transmitter guarantees that the receiver decodes its message and that the eavesdropper is kept in full ignorance about the message. The compound wiretap channel can also be viewed as a multicast channel with multiple eavesdroppers, in which the transmitter sends information to all receivers and keeps the information secret from all eavesdroppers. For the discrete memoryless channel, lower and upper bounds on the secrecy capacity are derived. The secrecy capacity is established for the degraded channel and the semideterministic channel with one receiver. The parallel Gaussian channel is further studied. The secrecy capacity and the secrecy degree of freedom (s.d.o.f. are derived for the degraded case with one receiver. Schemes to achieve the s.d.o.f. for the case with two receivers and two eavesdroppers are constructed to demonstrate the necessity of a prefix channel in encoder design. Finally, the multi-antenna (i.e., MIMO compound wiretap channel is studied. The secrecy capacity is established for the degraded case and an achievable s.d.o.f. is given for the general case.

  5. New Trends in Cancer Therapy: Targeting Ion Channels and Transporters

    Directory of Open Access Journals (Sweden)

    Annarosa Arcangeli

    2010-04-01

    Full Text Available The expression and activity of different channel types mark and regulate specific stages of cancer establishment and progression. Blocking channel activity impairs the growth of some tumors, both in vitro and in vivo, which opens a new field for pharmaceutical research. However, ion channel blockers may produce serious side effects, such as cardiac arrhythmias. For instance, Kv11.1 (hERG1 channels are aberrantly expressed in several human cancers, in which they control different aspects of the neoplastic cell behaviour. hERG1 blockers tend to inhibit cancer growth. However they also retard the cardiac repolarization, thus lengthening the electrocardiographic QT interval, which can lead to life-threatening ventricular arrhythmias. Several possibilities exist to produce less harmful compounds, such as developing specific drugs that bind hERG1 channels in the open state or disassemble the ion channel/integrin complex which appears to be crucial in certain stages of neoplastic progression. The potential approaches to improve the efficacy and safety of ion channel targeting in oncology include: (1 targeting specific conformational channel states; (2 finding ever more specific inhibitors, including peptide toxins, for channel subtypes mainly expressed in well-identified tumors; (3 using specific ligands to convey traceable or cytotoxic compounds; (4 developing channel blocking antibodies; (5 designing new molecular tools to decrease channel expression in selected cancer types. Similar concepts apply to ion transporters such as the Na+/K+ pump and the Na+/H+ exchanger. Pharmacological targeting of these transporters is also currently being considered in anti-neoplastic therapy.

  6. Global versus local mechanisms of temperature sensing in ion channels.

    Science.gov (United States)

    Arrigoni, Cristina; Minor, Daniel L

    2018-05-01

    Ion channels turn diverse types of inputs, ranging from neurotransmitters to physical forces, into electrical signals. Channel responses to ligands generally rely on binding to discrete sensor domains that are coupled to the portion of the channel responsible for ion permeation. By contrast, sensing physical cues such as voltage, pressure, and temperature arises from more varied mechanisms. Voltage is commonly sensed by a local, domain-based strategy, whereas the predominant paradigm for pressure sensing employs a global response in channel structure to membrane tension changes. Temperature sensing has been the most challenging response to understand and whether discrete sensor domains exist for pressure and temperature has been the subject of much investigation and debate. Recent exciting advances have uncovered discrete sensor modules for pressure and temperature in force-sensitive and thermal-sensitive ion channels, respectively. In particular, characterization of bacterial voltage-gated sodium channel (BacNa V ) thermal responses has identified a coiled-coil thermosensor that controls channel function through a temperature-dependent unfolding event. This coiled-coil thermosensor blueprint recurs in other temperature sensitive ion channels and thermosensitive proteins. Together with the identification of ion channel pressure sensing domains, these examples demonstrate that "local" domain-based solutions for sensing force and temperature exist and highlight the diversity of both global and local strategies that channels use to sense physical inputs. The modular nature of these newly discovered physical signal sensors provides opportunities to engineer novel pressure-sensitive and thermosensitive proteins and raises new questions about how such modular sensors may have evolved and empowered ion channel pores with new sensibilities.

  7. Seasonal Change in Nearshore and Channel Morphology at Packery Channel, A New Inlet Serving Corpus Christi, Texas

    Science.gov (United States)

    2011-01-01

    position defined by limiting features such as the dune toe or seawall. Individual transects are spaced at 1 to 30 m apart. These surveys usually require...associated nominal depths (MSL) are: 1) a wading survey conducted from the landward limiting feature, such as dune or seawall, to offshore depth of...Hall Pier. The surge forced water up to the dune line adjacent to the channel. The water was funneled toward and into the inlet, introducing sand from

  8. Touch, Tension, and Transduction - The Function and Regulation of Piezo Ion Channels.

    Science.gov (United States)

    Wu, Jason; Lewis, Amanda H; Grandl, Jörg

    2017-01-01

    In 2010, two proteins, Piezo1 and Piezo2, were identified as the long-sought molecular carriers of an excitatory mechanically activated current found in many cells. This discovery has opened the floodgates for studying a vast number of mechanotransduction processes. Over the past 6 years, groundbreaking research has identified Piezos as ion channels that sense light touch, proprioception, and vascular blood flow, ruled out roles for Piezos in several other mechanotransduction processes, and revealed the basic structural and functional properties of the channel. Here, we review these findings and discuss the many aspects of Piezo function that remain mysterious, including how Piezos convert a variety of mechanical stimuli into channel activation and subsequent inactivation, and what molecules and mechanisms modulate Piezo function. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Promotion through Marketing Channels : The Case of Kosovo

    Directory of Open Access Journals (Sweden)

    MSc. Hidajet Karaxha

    2016-01-01

    Full Text Available In order for a product to be put in the hands of the customer, requires a mechanism which is called distribution channel and which enables the connection between the consumer and producer. One of the many strategies applied by Kosovar companies for the involvement of the members of the channel is also the promotion through distribution channels. Therefore, the strategies which involve the members of the channel have a higher probability to be positively accepted by the members of the channel, when they are part of a general program of supporting the needs of the producers. The process of realizing a marketing strategy of a company does not concise only of achieving specific goals of production during the realization of the promotion phase, but it also requires identifying the target market and achieving it. The purpose of this paper is to review the promotion strategy of distribution channels, which emphasize the support by the members of the channel, initiated by the producers through cooperative advertisements, promotional salaries, slotting taxes, incentives, promotions in markets and also special promotional agreements. The theoretical and practical side of the study are very important, especially regarding to new theoretical and practical views in the study context. Besides the theoretical contribution that will be offered by this paper, there will also be interesting findings in the practical aspect where through this paper, the owners, managers, firms will be able to understand the role and importance of promotion through distribution channels. Knowing that there are only few studies offered in this field, this paper offers help for everyone interested in this field. This paper contains empirical data collected by questionnaires and interviews.

  10. Method of stabilizing single channel analyzers

    International Nuclear Information System (INIS)

    Fasching, G.E.; Patton, G.H.

    1975-01-01

    A method and the apparatus to reduce the drift of single channel analyzers are described. Essentially, this invention employs a time-sharing or multiplexing technique to insure that the outputs from two single channel analyzers (SCAS) maintain the same count ratio regardless of variations in the threshold voltage source or voltage changes, the multiplexing technique is accomplished when a flip flop, actuated by a clock, changes state to switch the output from the individual SCAS before these outputs are sent to a ratio counting scalar. In the particular system embodiment disclosed that illustrates this invention, the sulfur content of coal is determined by subjecting the coal to radiation from a neutron producing source. A photomultiplier and detector system equates the transmitted gamma radiation to an analog voltage signal and sends the same signal after amplification, to a SCA system that contains the invention. Therein, at least two single channel analyzers scan the analog signal over different parts of a spectral region. The two outputs may then be sent to a digital multiplexer so that the output from the multiplexer contains counts falling within two distinct segments of the region. By dividing the counts from the multiplexer by each other, the percentage of sulfur within the coal sample under observation may be determined. (U.S.)

  11. Channel Extension in Deep-Water Distributive Systems

    Science.gov (United States)

    Hoyal, D. C.; Sheets, B. A.

    2007-12-01

    The cyclic nature of channel and lobe formation in submarine fans is the result of the unstable and ephemeral nature of newly formed distributary channels. Avulsion cycles are initiated as unconfined sheet flow immediately following avulsion followed by stages of channel incision and extension, deposition of channel mouth deposits, and often channel backfilling. In contrast with those in alluvial and deltaic environments, avulsion cycles in submarine fans are relatively poorly understood due to the difficulty of observing deep ocean processes, either over short timescales needed to measure the hydrodynamics of active turbidity currents, or over longer timescales needed for the morphodynamic evolution of individual distributary channels and avulsion events. Here we report the results of over 80 experiments in a 5m x 3m x1m deep tank using saline (NaCl) density flows carrying low-density plastic sediment (SG 1.5) flowing down an inclined ramp. These experiments were designed to investigate trends observed in earlier self-organized experimental submarine fans with well-developed avulsion cycles, in which distributive lobes were observed to form on relatively high slopes. In particular, we were interested in investigating the relationship between channel extension length (distance from the inlet to the point where the flow becomes de-channelized, transitioning into a mouth-bar/lobe) and slope. The results of the experiments are clear but counter-intuitive. Channels appear to extend in discrete segments and channel extension length is inversely related to slope over a wide range of slopes (5-17 degrees). In addition, channel extension seems largely independent of inlet flow density (salt concentration) over the experimental range (10-24 g/cc). Measurements of densimetric Froude number (Fr') indicate Fr' increases downstream to near critical conditions at the channel lobe transition. Our preliminary interpretation is that distributary channels become unstable due to

  12. PIP2 mediates functional coupling and pharmacology of neuronal KCNQ channels

    DEFF Research Database (Denmark)

    Kim, Robin Y; Pless, Stephan A; Kurata, Harley T

    2017-01-01

    Retigabine (RTG) is a first-in-class antiepileptic drug that suppresses neuronal excitability through the activation of voltage-gated KCNQ2-5 potassium channels. Retigabine binds to the pore-forming domain, causing a hyperpolarizing shift in the voltage dependence of channel activation. To elucid......Retigabine (RTG) is a first-in-class antiepileptic drug that suppresses neuronal excitability through the activation of voltage-gated KCNQ2-5 potassium channels. Retigabine binds to the pore-forming domain, causing a hyperpolarizing shift in the voltage dependence of channel activation....... These findings reveal an important role for PIP2 in coupling retigabine binding to altered VSD function. We identify a polybasic motif in the proximal C terminus of retigabine-sensitive KCNQ channels that contributes to VSD-pore coupling via PIP2, and thereby influences the unique gating effects of retigabine....

  13. Carbonate Channel-Levee Systems Influenced by Mass-Transport Deposition, Browse Basin, Australia

    Science.gov (United States)

    Dunlap, D.; Janson, X.; Sanchez-Phelps, C.; Covault, J. A.

    2017-12-01

    Submarine channels are primary conduits for clastic sediment transport to deep-water basins, thereby controlling the location of marine depocenters and sediment bypass. The evolution and depositional character of submarine channels have broad implications to sediment dispersal, sediment quality, and hydrocarbon exploration potential. Siliciclastic channel systems have been extensively studied in modern environments, seismic and outcrop; however, carbonate channel-levee deposits have only recently been explored. Here we utilize newly released high-resolution (90 Hz) seismic-reflection data from the Australian Browse Basin to document the influence of mass-transport complex (MTC) deposition on the stratigraphic architecture of carbonate channel-levee systems. The 2014 vintage seismic survey is 2500 km2 and hosts numerous large Miocene-age carbonate channel-levee complexes basinward of the shelf edge. Regional horizons and individual channel forms were mapped. Channels range from 200-300 m wide and are bounded by high-relief levee-overbank wedges (>100 ms TWTT). These channels extend across the survey area >70 km. The leveed-channels were sourced from middle and late Miocene slope gullies linked to platform carbonates. Slope-attached and locally derived MTC's are evident throughout the Miocene section likely related to periods of basin inversion and shelf-edge gully incision. We interpret that regionally extensive (>1000 km2) slope-attached MTC's can shut down a channel-levee system and trigger the initiation of a new system, whereas more locally derived (wasting and turbidity currents, which informs depositional models of carbonate slope systems and calls for re-evaluation of the controls on stratigraphic patterns in mixed siliciclastic-carbonate deep-water basins.

  14. Stress, cortisol, and obesity: a role for cortisol responsiveness in identifying individuals prone to obesity.

    Science.gov (United States)

    Hewagalamulage, S D; Lee, T K; Clarke, I J; Henry, B A

    2016-07-01

    There is a strong inter-relationship between activation of the hypothalamo-pituitary-adrenal axis and energy homeostasis. Patients with abdominal obesity have elevated cortisol levels. Furthermore, stress and glucocorticoids act to control both food intake and energy expenditure. In particular, glucocorticoids are known to increase the consumption of foods enriched in fat and sugar. It is well-known that, in all species, the cortisol response to stress or adrenocorticotropin is highly variable. It has now emerged that cortisol responsiveness is an important determinant in the metabolic sequelae to stress. Sheep that are characterized as high-cortisol responders (HRs) have greater propensity to weight gain and obesity than low-cortisol responders (LRs). This difference in susceptibility to become obese is associated with a distinct metabolic, neuroendocrine, and behavioral phenotype. In women and ewes, HR individuals eat more in response to stress than LR. Furthermore, HR sheep have impaired melanocortin signaling and reduced skeletal muscle thermogenesis. High-cortisol responder sheep exhibit reactive coping strategies, whereas LRs exhibit proactive coping strategies. This complex set of traits leads to increased food intake and reduced energy expenditure in HR and thus, predisposition to obesity. We predict that cortisol responsiveness may be used as a marker to identify individuals who are at risk of weight gain and subsequent obesity. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Zirconium ignition in exposed fuel channel

    Energy Technology Data Exchange (ETDEWEB)

    Elias, E., E-mail: merezra@technion.ac.il; Hasan, D.; Nekhamkin, Y.

    2015-05-15

    Highlights: • We demonstrate the idea of runaway zirconium–steam reactions in severe accidents in today's LWRs. • We predict the thermal-hydraulics conditions relevant to cladding oxidation in an exposed fuel channel of a partially uncovered core. • The Semenov theory of metal combustion is extended to define a criterion for runaway oxidation reaction in fuel cladding. - Abstract: A theoretical model based on simultaneous solution of the heat and mass transfer equations is developed for predicting the rate of thermo-chemical reaction between zirconium cladding and a hot steam environment. Ignition conditions relevant to cladding oxidation in an exposed fuel channel of a partially uncovered core are predicted based on the theory of metal combustion. A range of decay power, convective heat transfer coefficients, and initial temperatures leading to uncontrolled runaway cladding oxidation is identified. The model could be readily integrated as part of a fuel channel analysis code for predicting possible outcomes of different accident mitigation procedures in light water nuclear reactors under LOCA conditions.

  16. Conductance of Ion Channels - Theory vs. Experiment

    Science.gov (United States)

    Pohorille, Andrew; Wilson, Michael; Mijajlovic, Milan

    2013-01-01

    . In addition, once the free energy profile becomes available the full current-voltage dependence can be readily obtained. For both channels we carried out calculations using both approaches. We also tested the main assumptions underlying the diffusive model, such as uncorrelated nature of individual crossing events and Fickian diffusion. The accuracy and consistency of different methods will be discussed. Finally we will discuss how comparisons between calculated and measured ionic conductance and selectivity of transport can be used for determining structural models of the channels.

  17. A Bayesian matching pursuit based scheduling algorithm for feedback reduction in MIMO broadcast channels

    KAUST Repository

    Shibli, Hussain J.

    2013-06-01

    Opportunistic schedulers rely on the feedback of all users in order to schedule a set of users with favorable channel conditions. While the downlink channels can be easily estimated at all user terminals via a single broadcast, several key challenges are faced during uplink transmission. First of all, the statistics of the noisy and fading feedback channels are unknown at the base station (BS) and channel training is usually required from all users. Secondly, the amount of network resources (air-time) required for feedback transmission grows linearly with the number of users. In this paper, we tackle the above challenges and propose a Bayesian based scheduling algorithm that 1) reduces the air-time required to identify the strong users, and 2) is agnostic to the statistics of the feedback channels and utilizes the a priori statistics of the additive noise to identify the strong users. Numerical results show that the proposed algorithm reduces the feedback air-time while improving detection in the presence of fading and noisy channels when compared to recent compressed sensing based algorithms. Furthermore, the proposed algorithm achieves a sum-rate throughput close to that obtained by noiseless dedicated feedback systems. © 2013 IEEE.

  18. Design and characterization of a single channel two-liquid capacitor and its application to hyperelastic strain sensing.

    Science.gov (United States)

    Liu, Shanliangzi; Sun, Xiaoda; Hildreth, Owen J; Rykaczewski, Konrad

    2015-03-07

    Room temperature liquid-metal microfluidic devices are attractive systems for hyperelastic strain sensing. These liquid-phase electronics are intrinsically soft and retain their functionality even when stretched to several times their original length. Currently two types of liquid metal-based strain sensors exist for in-plane measurements: single-microchannel resistive and two-microchannel capacitive devices. With a winding serpentine channel geometry, these sensors typically have a footprint of about a square centimeter. This large footprint of an individual device limits the number of sensors that can be embedded into, for example, electronic fabric or skin. In this work we introduce an alternative capacitor design consisting of two liquid metal electrodes separated by a liquid dielectric material within a single straight channel. Using a liquid insulator instead of a solid elastomer enables us to tailor the system's capacitance by selecting high or low dielectric constant liquids. We quantify the effects of the electrode geometry including the diameter, spacing, and meniscus shape as well as the dielectric constant of the insulating liquid on the overall system's capacitance. We also develop a procedure for fabricating the two-liquid capacitor within a single straight polydiemethylsiloxane channel and demonstrate that this device can have about 25 times higher capacitance per sensor's base area when compared to two-channel liquid metal capacitors. Lastly, we characterize the response of this compact device to strain and identify operational issues arising from complex hydrodynamics near liquid-liquid and liquid-elastomer interfaces.

  19. Quantum Channels With Memory

    International Nuclear Information System (INIS)

    Rybar, T.

    2012-01-01

    Quantum memory channels represent a very general, yet simple and comprehensible model for causal processes. As such they have attracted considerable research interest, mostly aimed on their transfer capabilities and structure properties. Most notably it was shown that memory channels can be implemented via physically naturally motivated collision models. We also define the concept of repeatable channels and show that only unital channels can be implemented repeat ably with pure memory channels. In the special case of qubit channels we also show that every unital qubit channel has a repeatable implementation. We also briefly explore the possibilities of stroboscopical simulation of channels and show that all random unitary channels can be stroboscopically simulated. Particularly in qubit case, all indivisible qubit channels are also random unitary, hence for qubit all indivisible channels can be stroboscopically simulated. Memory channels also naturally capture the framework of correlated experiments. We develop methods to gather and interpret data obtained in such setting and in detail examine the two qubit case. We also show that for control unitary interactions the measured data will never contradict a simple unitary evolution. Thus no memory effects can be spotted then. (author)

  20. Molecular mechanism of voltage sensing in voltage-gated proton channels

    Science.gov (United States)

    Rebolledo, Santiago; Perez, Marta E.

    2013-01-01

    Voltage-gated proton (Hv) channels play an essential role in phagocytic cells by generating a hyperpolarizing proton current that electrically compensates for the depolarizing current generated by the NADPH oxidase during the respiratory burst, thereby ensuring a sustained production of reactive oxygen species by the NADPH oxidase in phagocytes to neutralize engulfed bacteria. Despite the importance of the voltage-dependent Hv current, it is at present unclear which residues in Hv channels are responsible for the voltage activation. Here we show that individual neutralizations of three charged residues in the fourth transmembrane domain, S4, all reduce the voltage dependence of activation. In addition, we show that the middle S4 charged residue moves from a position accessible from the cytosolic solution to a position accessible from the extracellular solution, suggesting that this residue moves across most of the membrane electric field during voltage activation of Hv channels. Our results show for the first time that the charge movement of these three S4 charges accounts for almost all of the measured gating charge in Hv channels. PMID:23401575

  1. Touch, Tension, and Transduction – the Function and Regulation of Piezo Ion Channels

    Science.gov (United States)

    Wu, Jason; Lewis, Amanda; Grandl, Jörg

    2016-01-01

    In 2010, two proteins, Piezo1 and Piezo2, were identified as the long-sought molecular carriers of an excitatory mechanically activated current found in many cells. This discovery has opened the floodgates for studying a vast number of mechanotransduction processes. Over the past six years, groundbreaking research has identified Piezos as ion channels that sense light touch, proprioception, and vascular blood flow, ruled out roles for Piezos in several other mechanotransduction processes, and revealed the basic structural and functional properties of the channel. Here, we review these findings and discuss the many aspects of Piezo function that remain mysterious, including how Piezos convert a variety of mechanical stimuli into channel activation and subsequent inactivation, and what molecules and mechanisms modulate Piezo function. PMID:27743844

  2. Mimicking multi-channel scattering with single-channel approaches

    OpenAIRE

    Grishkevich, Sergey; Schneider, Philipp-Immanuel; Vanne, Yulian V.; Saenz, Alejandro

    2009-01-01

    The collision of two atoms is an intrinsic multi-channel (MC) problem as becomes especially obvious in the presence of Feshbach resonances. Due to its complexity, however, single-channel (SC) approximations, which reproduce the long-range behavior of the open channel, are often applied in calculations. In this work the complete MC problem is solved numerically for the magnetic Feshbach resonances (MFRs) in collisions between generic ultracold 6Li and 87Rb atoms in the ground state and in the ...

  3. Fine Channel Networks

    Science.gov (United States)

    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.

  4. Sub-nanometre channels embedded in two-dimensional materials

    KAUST Repository

    Han, Yimo

    2017-12-04

    Two-dimensional (2D) materials are among the most promising candidates for next-generation electronics due to their atomic thinness, allowing for flexible transparent electronics and ultimate length scaling1. Thus far, atomically thin p–n junctions2,3,4,5,6,7,8, metal–semiconductor contacts9,10,11, and metal–insulator barriers12,13,14 have been demonstrated. Although 2D materials achieve the thinnest possible devices, precise nanoscale control over the lateral dimensions is also necessary. Here, we report the direct synthesis of sub-nanometre-wide one-dimensional (1D) MoS2 channels embedded within WSe2 monolayers, using a dislocation-catalysed approach. The 1D channels have edges free of misfit dislocations and dangling bonds, forming a coherent interface with the embedding 2D matrix. Periodic dislocation arrays produce 2D superlattices of coherent MoS2 1D channels in WSe2. Using molecular dynamics simulations, we have identified other combinations of 2D materials where 1D channels can also be formed. The electronic band structure of these 1D channels offers the promise of carrier confinement in a direct-gap material and the charge separation needed to access the ultimate length scales necessary for future electronic applications.

  5. Calibration through on-line monitoring of instruments channels

    International Nuclear Information System (INIS)

    James, R.W.

    1996-01-01

    Plant technical specifications require periodic calibration of instrument channels, and this has traditionally meant calibration at fixed time intervals for nearly all instruments. Experience has shown that unnecessarily frequent calibrations reduce channel availability and reliability, impact outage durations, and increase maintenance costs. An alternative approach to satisfying existing requirements for periodic calibration consists of on-line monitoring and quantitative comparison of instrument channels during operation to identify instrument degradation and failure. A Utility Working Group has been formed by EPRI to support the technical activities necessary to achieve generic NRC acceptance of on-line monitoring of redundant instrument channels as a basis for determining when to perform calibrations. A topical report proposing NRC acceptance of this approach was submitted in August 1995, and the Working Group is currently resolving NRC technical questions. This paper describes the proposed approach and the current status of the topical report with regard to NRC review. While these activities will not preclude utilities from continuing to use existing calibration approaches, successful acceptance of this performance-based approach will allow utilities to substantially reduce the number of calibrations which are performed. Concurrent benefits will include reduced I ampersand C impact on outage durations and improved sensitivity to instrument channel performance

  6. Assessment of long-term channel changes in the Mekong River using remote sensing and a channel-evolution model

    Science.gov (United States)

    Miyazawa, N.

    2011-12-01

    River-channel changes are a key factor affecting physical, ecological and management issues in the fluvial environment. In this study, long-term channel changes in the Mekong River were assessed using remote sensing and a channel-evolution model. A channel-evolution model for calculating long-term channel changes of a measndering river was developed using a previous fluid-dynamic model [Zolezzi and Seminara, 2001], and was applied in order to quantify channel changes of two meandering reaches in the Mekong River. Quite few attempts have been made so far to combine remote sensing observation of meandering planform change with the application of channel evolution models within relatively small-scale gravel-bed systems in humid temperate regions. The novel point of the present work is to link state-of-art meandering planform evolution model with observed morphological changes within large-scale sand-bed rivers with higher bank height in tropical monsoonal climate regions, which are the highly dynamic system, and assess the performance. Unstable extents of the reaches could be historically identified using remote-sensing technique. The instability caused i) bank erosion and accretion of meander bends and ii) movement or development of bars and changes in the flow around the bars. The remote sensing measurements indicate that maximum erosion occurred downstream of the maximum curvature of the river-center line in both reaches. The model simulations indicates that under the mean annual peak discharge the maximum of excess longitudinal velocity near the banks occurs downstream of the maximum curvature in both reaches. The channel migration coefficients of the reaches were calibrated by comparing remote-sensing measurements and model simulations. The diffrence in the migration coefficients between both reaches depends on the diffrence in bank height rather than the geotechnical properties of floodplain sediments. Possible eroded floodplain areas and accreted floodplain

  7. Control system devices : architectures and supply channels overview.

    Energy Technology Data Exchange (ETDEWEB)

    Trent, Jason; Atkins, William Dee; Schwartz, Moses Daniel; Mulder, John C.

    2010-08-01

    This report describes a research project to examine the hardware used in automated control systems like those that control the electric grid. This report provides an overview of the vendors, architectures, and supply channels for a number of control system devices. The research itself represents an attempt to probe more deeply into the area of programmable logic controllers (PLCs) - the specialized digital computers that control individual processes within supervisory control and data acquisition (SCADA) systems. The report (1) provides an overview of control system networks and PLC architecture, (2) furnishes profiles for the top eight vendors in the PLC industry, (3) discusses the communications protocols used in different industries, and (4) analyzes the hardware used in several PLC devices. As part of the project, several PLCs were disassembled to identify constituent components. That information will direct the next step of the research, which will greatly increase our understanding of PLC security in both the hardware and software areas. Such an understanding is vital for discerning the potential national security impact of security flaws in these devices, as well as for developing proactive countermeasures.

  8. A methodology for delineating planning-level channel migration zones.

    Science.gov (United States)

    2014-07-01

    The Washington State administrative codes that implement the Shoreline Management Act (SMA) require communities to identify the general location of channel migration zones (CMZs), and regulate development within these areas on shoreline streams. Shor...

  9. Volume Regulated Channels

    DEFF Research Database (Denmark)

    Klausen, Thomas Kjær

    of volume perturbations evolution have developed system of channels and transporters to tightly control volume homeostasis. In the past decades evidence has been mounting, that the importance of these volume regulated channels and transporters are not restricted to the defense of cellular volume...... but are also essential for a number of physiological processes such as proliferation, controlled cell death, migration and endocrinology. The thesis have been focusing on two Channels, namely the swelling activated Cl- channel (ICl, swell) and the transient receptor potential Vanilloid (TRPV4) channel. I: Cl......- serves a multitude of functions in the mammalian cell, regulating the membrane potential (Em), cell volume, protein activity and the driving force for facilitated transporters giving Cl- and Cl- channels a major potential of regulating cellular function. These functions include control of the cell cycle...

  10. Extraction of Multithread Channel Networks With a Reduced-Complexity Flow Model

    Science.gov (United States)

    Limaye, Ajay B.

    2017-10-01

    Quantitative measures of channel network geometry inform diverse applications in hydrology, sediment transport, ecology, hazard assessment, and stratigraphic prediction. These uses require a clear, objectively defined channel network. Automated techniques for extracting channels from topography are well developed for convergent channel networks and identify flow paths based on land-surface gradients. These techniques—even when they allow multiple flow paths—do not consistently capture channel networks with frequent bifurcations (e.g., in rivers, deltas, and alluvial fans). This paper uses multithread rivers as a template to develop a new approach for channel extraction suitable for channel networks with divergences. Multithread channels are commonly mapped using observed inundation extent, and I generalize this approach using a depth-resolving, reduced-complexity flow model to map inundation patterns for fixed topography across an arbitrary range of discharge. A case study for the Platte River, Nebraska, reveals that (1) the number of bars exposed above the water surface, bar area, and the number of wetted channel threads (i.e., braiding index) peak at intermediate discharge; (2) the anisotropic scaling of bar dimensions occurs for a range of discharge; and (3) the maximum braiding index occurs at a corresponding reference discharge that provides an objective basis for comparing the planform geometry of multithread rivers. Mapping by flow depth overestimates braiding index by a factor of 2. The new approach extends channel network extraction from topography to the full spectrum of channel patterns, with the potential for comparing diverse channel patterns at scales from laboratory experiments to natural landscapes.

  11. Streambed adjustment and channel widening in eastern Nebraska

    Science.gov (United States)

    Rus, David L.; Dietsch, Benjamin J.; Simon, Andrew

    2003-01-01

    In eastern Nebraska, stream straightening and dredging efforts since the 1890s have disturbed the natural equilibrium of stream channels and have led to streambed adjustment by degradation and subsequent channel widening. This report describes a study to evaluate the effect these disturbances have had on stream channels in eastern Nebraska. Two sets of survey data were collected approximately 2 years apart during 1996-99 at 151 primary sites. Additionally, historical streambed-elevation data (dating back to the 1890s) were compiled from several sources for the primary sites and 45 supplemental sites, and relevant disturbances were identified for each of eight basin groupings. Streambed-elevation data sets were used to estimate the amount of change to the streambed at the sites over the time period of the data. Recent channel widening was documented for 73 of the primary sites by comparing the two survey sets. The majority of observed streambed-gradation responses appear to be related to the various straightening efforts and to the effects of grade-control structures in the study area. Channel responses were complicated by the presence of multiple disturbances. However, in many cases, the streambed-elevation data sets provide a reliable representation of the past streambed gradation, with some sites showing 6 to 7 meters of degradation since they were straightened. Many sites that had been straightened showed considerable degradation following the disturbance. This indicates that eastern Nebraska stream channels can regain equilibrium mainly through the slope adjustment process of head-ward-progressing degradation. Bank failures were documented at sites in all eight of the basin groupings analyzed, and widening rates were computed at 64 of 73 sites. Observed bank widening in the Big Blue River Basin, a relatively unstraightened basin, indicates that other disturbances besides stream-channel straightening may be causing channel responses in the basin and possibly in

  12. Two-phase flow instability and bifurcation analysis of inclined multiple uniformly heated channels - 15107

    International Nuclear Information System (INIS)

    Mishra, A.M.; Paul, S.; Singh, S.; Panday, V.

    2015-01-01

    In this paper the two-phase flow instability analysis of multiple heated channels with various inclinations is studied. In addition, the bifurcation analysis is also carried out to capture the nonlinear dynamics of the system and to identify the regions in parameter space for which subcritical and supercritical bifurcations exist. In order to carry out the analysis, the system is mathematically represented by nonlinear Partial Differential Equation (PDE) for mass, momentum and energy in single as well as two-phase region. Then converted into Ordinary Differential Equation (ODE) using weighted residual method. Also, coupling equation is being used under the assumption that pressure drop in each channel is the same and the total mass flow rate is equal to sum of the individual mass flow rates. The homogeneous equilibrium model is used for the analysis. Stability Map is obtained in terms of phase change number (Npch) and Subcooling Number (Nsb) by solving a set of nonlinear, coupled algebraic equations obtained at equilibrium using Newton Raphson Method. MATLAB Code is verified by comparing it with results obtained by Matcont (Open source software) under same parametric values. Numerical simulations of the time-dependent, nonlinear ODEs are carried out for selected points in the operating parameter space to obtain the actual damped and growing oscillations in the channel inlet flow velocity which confirms the stability region across the stability map. Generalized Hopf (GH) points are observed for different inclinations, they are also points for subcritical and supercritical bifurcations. (authors)

  13. Robust Distributed Kalman Filter for Wireless Sensor Networks with Uncertain Communication Channels

    Directory of Open Access Journals (Sweden)

    Du Yong Kim

    2012-01-01

    Full Text Available We address a state estimation problem over a large-scale sensor network with uncertain communication channel. Consensus protocol is usually used to adapt a large-scale sensor network. However, when certain parts of communication channels are broken down, the accuracy performance is seriously degraded. Specifically, outliers in the channel or temporal disconnection are avoided via proposed method for the practical implementation of the distributed estimation over large-scale sensor networks. We handle this practical challenge by using adaptive channel status estimator and robust L1-norm Kalman filter in design of the processor of the individual sensor node. Then, they are incorporated into the consensus algorithm in order to achieve the robust distributed state estimation. The robust property of the proposed algorithm enables the sensor network to selectively weight sensors of normal conditions so that the filter can be practically useful.

  14. Evolutionary conservation and changes in insect TRP channels.

    Science.gov (United States)

    Matsuura, Hironori; Sokabe, Takaaki; Kohno, Keigo; Tominaga, Makoto; Kadowaki, Tatsuhiko

    2009-09-10

    TRP (Transient Receptor Potential) channels respond to diverse stimuli and thus function as the primary integrators of varied sensory information. They are also activated by various compounds and secondary messengers to mediate cell-cell interactions as well as to detect changes in the local environment. Their physiological roles have been primarily characterized only in mice and fruit flies, and evolutionary studies are limited. To understand the evolution of insect TRP channels and the mechanisms of integrating sensory inputs in insects, we have identified and compared TRP channel genes in Drosophila melanogaster, Bombyx mori, Tribolium castaneum, Apis mellifera, Nasonia vitripennis, and Pediculus humanus genomes as part of genome sequencing efforts. All the insects examined have 2 TRPV, 1 TRPN, 1 TRPM, 3 TRPC, and 1 TRPML subfamily members, demonstrating that these channels have the ancient origins in insects. The common pattern also suggests that the mechanisms for detecting mechanical and visual stimuli and maintaining lysosomal functions may be evolutionarily well conserved in insects. However, a TRPP channel, the most ancient TRP channel, is missing in B. mori, A. mellifera, and N. vitripennis. Although P. humanus and D. melanogaster contain 4 TRPA subfamily members, the other insects have 5 TRPA subfamily members. T. castaneum, A. mellifera, and N. vitripennis contain TRPA5 channels, which have been specifically retained or gained in Coleoptera and Hymenoptera. Furthermore, TRPA1, which functions for thermotaxis in Drosophila, is missing in A. mellifera and N. vitripennis; however, they have other Hymenoptera-specific TRPA channels (AmHsTRPA and NvHsTRPA). NvHsTRPA expressed in HEK293 cells is activated by temperature increase, demonstrating that HsTRPAs function as novel thermal sensors in Hymenoptera. The total number of insect TRP family members is 13-14, approximately half that of mammalian TRP family members. As shown for mammalian TRP channels, this

  15. Evolutionary conservation and changes in insect TRP channels

    Directory of Open Access Journals (Sweden)

    Tominaga Makoto

    2009-09-01

    Full Text Available Abstract Background TRP (Transient Receptor Potential channels respond to diverse stimuli and thus function as the primary integrators of varied sensory information. They are also activated by various compounds and secondary messengers to mediate cell-cell interactions as well as to detect changes in the local environment. Their physiological roles have been primarily characterized only in mice and fruit flies, and evolutionary studies are limited. To understand the evolution of insect TRP channels and the mechanisms of integrating sensory inputs in insects, we have identified and compared TRP channel genes in Drosophila melanogaster, Bombyx mori, Tribolium castaneum, Apis mellifera, Nasonia vitripennis, and Pediculus humanus genomes as part of genome sequencing efforts. Results All the insects examined have 2 TRPV, 1 TRPN, 1 TRPM, 3 TRPC, and 1 TRPML subfamily members, demonstrating that these channels have the ancient origins in insects. The common pattern also suggests that the mechanisms for detecting mechanical and visual stimuli and maintaining lysosomal functions may be evolutionarily well conserved in insects. However, a TRPP channel, the most ancient TRP channel, is missing in B. mori, A. mellifera, and N. vitripennis. Although P. humanus and D. melanogaster contain 4 TRPA subfamily members, the other insects have 5 TRPA subfamily members. T. castaneum, A. mellifera, and N. vitripennis contain TRPA5 channels, which have been specifically retained or gained in Coleoptera and Hymenoptera. Furthermore, TRPA1, which functions for thermotaxis in Drosophila, is missing in A. mellifera and N. vitripennis; however, they have other Hymenoptera-specific TRPA channels (AmHsTRPA and NvHsTRPA. NvHsTRPA expressed in HEK293 cells is activated by temperature increase, demonstrating that HsTRPAs function as novel thermal sensors in Hymenoptera. Conclusion The total number of insect TRP family members is 13-14, approximately half that of mammalian TRP

  16. JADSPE, Multi-Channel Gamma Spectra Unfolding Program

    International Nuclear Information System (INIS)

    Rikovska, J.; Stejskalova, E.

    2005-01-01

    1 - Description of program or function: JADSPE is a package of eight programs to process multi-channel gamma-ray spectra. The programs can be used to: - locate automatically spectral peaks and calculate their positions, areas, and full widths at half maximum (FWHM); - plot the spectra on a CALCOMP plotter, TEKTRONIX terminal or a line printer; - add or subtract several spectra with the possibility of adjusting either their start and end channels or the maxima of the chosen corresponding peaks. The JADSPE package comprises the following programs: - SPECTF: automatic location of peaks and calculation of their positions, areas and FWHMS. The standard deviations of peak parameters are also determined, and each evaluated region is plotted on the line printer. - SPECT1: The areas and FWHMs are calculated for peaks whose positions are known beforehand. The standard deviations of calculated parameters are also determined, and each evaluated region is plotted on the line printer. - PLOCHA: The peak net area is calculated by summing the channel contents in specified regions and by subtracting a linear background. - GRAPH: Spectrum plotting on the line printer. - PLTNEW: Spectrum plotting on CALCOMP plotter or on TEKTRONIX terminal. - SUMDIF: The channel contents of several gamma-ray spectra are added or subtracted. - SSPFP: The channel contents of several gamma-ray spectra are added with adjustment of the maxima of specified peaks. - SOUCET: The channel contents of several gamma-ray spectra are added with the adjustment of start and end channels of the spectra. 2 - Method of solution: Non-linear least-square fit. 3 - Restrictions on the complexity of the problem: The full energy peaks are approximated by a symmetrical Gaussian function and the underlying background is approximated by a first-order polynomial. A fixed spectrum length of 4096 channels is assumed. Maxima of: - number of peaks in one multiplet: 9; - number of peaks identified by the automatic search procedure

  17. Slack sodium-activated potassium channel membrane expression requires p38 mitogen-activated protein kinase phosphorylation.

    Science.gov (United States)

    Gururaj, Sushmitha; Fleites, John; Bhattacharjee, Arin

    2016-04-01

    p38 MAPK has long been understood as an inducible kinase under conditions of cellular stress, but there is now increasing evidence to support its role in the regulation of neuronal function. Several phosphorylation targets have been identified, an appreciable number of which are ion channels, implicating the possible involvement of p38 MAPK in neuronal excitability. The KNa channel Slack is an important protein to be studied as it is highly and ubiquitously expressed in DRG neurons and is important in the maintenance of their firing accommodation. We sought to examine if the Slack channel could be a substrate of p38 MAPK activity. First, we found that the Slack C-terminus contains two putative p38 MAPK phosphorylation sites that are highly conserved across species. Second, we show via electrophysiology experiments that KNa currents and further, Slack currents, are subject to tonic modulation by p38 MAPK. Third, biochemical approaches revealed that Slack channel regulation by p38 MAPK occurs through direct phosphorylation at the two putative sites of interaction, and mutating both sites prevented surface expression of Slack channels. Based on these results, we conclude that p38 MAPK is an obligate regulator of Slack channel function via the trafficking of channels into the membrane. The present study identifies Slack KNa channels as p38 MAPK substrates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Nociceptive TRP Channels: Sensory Detectors and Transducers in Multiple Pain Pathologies

    Directory of Open Access Journals (Sweden)

    Aaron D. Mickle

    2016-11-01

    Full Text Available Specialized receptors belonging to the transient receptor potential (TRP family of ligand-gated ion channels constitute the critical detectors and transducers of pain-causing stimuli. Nociceptive TRP channels are predominantly expressed by distinct subsets of sensory neurons of the peripheral nervous system. Several of these TRP channels are also expressed in neurons of the central nervous system, and in non-neuronal cells that communicate with sensory nerves. Nociceptive TRPs are activated by specific physico-chemical stimuli to provide the excitatory trigger in neurons. In addition, decades of research has identified a large number of immune and neuromodulators as mediators of nociceptive TRP channel activation during injury, inflammatory and other pathological conditions. These findings have led to aggressive targeting of TRP channels for the development of new-generation analgesics. This review summarizes the complex activation and/or modulation of nociceptive TRP channels under pathophysiological conditions, and how these changes underlie acute and chronic pain conditions. Furthermore, development of small-molecule antagonists for several TRP channels as analgesics, and the positive and negative outcomes of these drugs in clinical trials are discussed. Understanding the diverse functional and modulatory properties of nociceptive TRP channels is critical to function-based drug targeting for the development of evidence-based and efficacious new generation analgesics.

  19. The Nav1.2 channel is regulated by GSK3

    Science.gov (United States)

    James, Thomas F.; Nenov, Miroslav N.; Wildburger, Norelle C.; Lichti, Cheryl; Luisi, Jonathan; Vergara, Fernanda; Panova-Electronova, Neli I.; Nilsson, Carol L.; Rudra, Jai; Green, Thomas A.; Labate, Demetrio; Laezza, Fernanda

    2015-01-01

    Background Phosphorylation plays an essential role in regulating the voltage-gated sodium (Nav) channels and excitability. Yet, a surprisingly limited number of kinases have been identified as regulators of Nav channels. Herein, we posited that glycogen synthase kinase 3 (GSK3), a critical kinase found associated with numerous brain disorders, might directly regulate neuronal Nav channels. Methods We used patch-clamp electrophysiology to record sodium currents from Nav1.2 channels stably expressed in HEK-293 cells. mRNA and protein levels were quantified with RT-PCR, Western blot, or confocal microscopy, and in vitro phosphorylation and mass spectrometry to identify phosphorylated residues. Results We found that exposure of cells to GSK3 inhibitor XIII significantly potentiates the peak current density of Nav1.2, a phenotype reproduced by silencing GSK3 with siRNA. Contrarily, overexpression of GSK3β suppressed Nav1.2-encoded currents. Neither mRNA nor total protein expression were changed upon GSK3 inhibition. Cell surface labeling of CD4-chimeric constructs expressing intracellular domains of the Nav1.2 channel indicates that cell surface expression of CD4-Nav1.2-Ctail was up-regulated upon pharmacological inhibition of GSK3, resulting in an increase of surface puncta at the plasma membrane. Finally, using in vitro phosphorylation in combination with high resolution mass spectrometry, we further demonstrate that GSK3β phosphorylates T1966 at the C-terminal tail of Nav1.2. Conclusion These findings provide evidence for a new mechanism by which GSK3 modulate Nav channel function via its C-terminal tail. General Significance These findings provide fundamental knowledge in understanding signaling dysfunction common in several neuropsychiatric disorders. PMID:25615535

  20. Biased and flow driven Brownian motion in periodic channels

    Science.gov (United States)

    Martens, S.; Straube, A.; Schmid, G.; Schimansky-Geier, L.; Hänggi, P.

    2012-02-01

    In this talk we will present an expansion of the common Fick-Jacobs approximation to hydrodynamically as well as by external forces driven Brownian transport in two-dimensional channels exhibiting smoothly varying periodic cross-section. We employ an asymptotic analysis to the components of the flow field and to stationary probability density for finding the particles within the channel in a geometric parameter. We demonstrate that the problem of biased Brownian dynamics in a confined 2D geometry can be replaced by Brownian motion in an effective periodic one-dimensional potential ψ(x) which takes the external bias, the change of the local channel width, and the flow velocity component in longitudinal direction into account. In addition, we study the influence of the external force magnitude, respectively, the pressure drop of the fluid on the particle transport quantities like the averaged velocity and the effective diffusion coefficient. The critical ratio between the external force and pressure drop where the average velocity equals zero is identified and the dependence of the latter on the channel geometry is derived. Analytic findings are confirmed by numerical simulations of the particle dynamics in a reflection symmetric sinusoidal channel.

  1. A protein interaction mechanism for suppressing the mechanosensitive Piezo channels.

    Science.gov (United States)

    Zhang, Tingxin; Chi, Shaopeng; Jiang, Fan; Zhao, Qiancheng; Xiao, Bailong

    2017-11-27

    Piezo proteins are bona fide mammalian mechanotransduction channels for various cell types including endothelial cells. The mouse Piezo1 of 2547 residues forms a three-bladed, propeller-like homo-trimer comprising a central pore-module and three propeller-structures that might serve as mechanotransduction-modules. However, the mechanogating and regulation of Piezo channels remain unclear. Here we identify the sarcoplasmic /endoplasmic-reticulum Ca 2+ ATPase (SERCA), including the widely expressed SERCA2, as Piezo interacting proteins. SERCA2 strategically suppresses Piezo1 via acting on a 14-residue-constituted intracellular linker connecting the pore-module and mechanotransduction-module. Mutating the linker impairs mechanogating and SERCA2-mediated modulation of Piezo1. Furthermore, the synthetic linker-peptide disrupts the modulatory effects of SERCA2, demonstrating the key role of the linker in mechanogating and regulation. Importantly, the SERCA2-mediated regulation affects Piezo1-dependent migration of endothelial cells. Collectively, we identify SERCA-mediated regulation of Piezos and the functional significance of the linker, providing important insights into the mechanogating and regulation mechanisms of Piezo channels.

  2. The Breakdown: Hillslope Sources of Channel Blocks in Bedrock Landscapes

    Science.gov (United States)

    Selander, B.; Anderson, S. P.; Rossi, M.

    2017-12-01

    Block delivery from hillslopes is a poorly understood process that influences bedrock channel incision rates and shapes steep terrain. Previous studies demonstrate that hillslope sediment delivery rate and grain size increases with channel downcutting rate or fracture density (Attal et al., 2015, ESurf). However, blocks that exceed the competence of the channel can inhibit incision. In Boulder Creek, a bedrock channel in the Colorado Front Range, large boulders (>1 m diameter) are most numerous in the steepest channel reaches; their distribution seems to reflect autogenic channel-hillslope feedback between incision rate and block delivery (Shobe et al., 2016, GRL). It is clear that the processes, rates of production, and delivery of large blocks from hillslopes into channels are critical to our understanding of steep terrain evolution. Fundamental questions are 1) whether block production or block delivery is rate limiting, 2) what mechanisms release blocks, and 3) how block production and transport affect slope morphology. As a first step, we map rock outcrops on the granodiorite hillslopes lining Boulder Creek within Boulder Canyon using a high resolution DEM. Our algorithm uses high ranges of curvature values in conjunction with slopes steeper than the angle of repose to quickly identify rock outcrops. We field verified mapped outcrop and sediment-mantled locations on hillslopes above and below the channel knickzone. We find a greater abundance of exposed rock outcrops on steeper hillslopes in Boulder Canyon. Additionally, we find that channel reaches with large in-channel blocks are located at the base of hillslopes with large areas of exposed bedrock, while reaches lacking large in-channel blocks tend to be at the base of predominately soil mantled and forested hillslopes. These observations support the model of block delivery and channel incision of Shobe et al. (2016, GRL). Moreover, these results highlight the conundrum of how rapid channel incision is

  3. A Gate Hinge Controls the Epithelial Calcium Channel TRPV5

    OpenAIRE

    van der Wijst, Jenny; Leunissen, Elizabeth H.; Blanchard, Maxime G.; Venselaar, Hanka; Verkaart, Sjoerd; Paulsen, Candice E.; Bindels, Ren? J.; Hoenderop, Joost G.

    2017-01-01

    TRPV5 is unique within the large TRP channel family for displaying a high Ca2+ selectivity together with Ca2+-dependent inactivation. Our study aims to uncover novel insights into channel gating through in-depth structure-function analysis. We identify an exceptional tryptophan (W583) at the terminus of the intracellular pore that is unique for TRPV5 (and TRPV6). A combination of site-directed mutagenesis, biochemical and electrophysiological analysis, together with homology modeling, demonst...

  4. The influence of log jam development on channel morphology in an intermediate sized coastal stream, Carnation Creek, B.C.

    Science.gov (United States)

    Luzi, D. S.; Sidle, R. C.; Hogan, D. L.

    2006-12-01

    Large wood (LW) is an important functional and structural component of forest stream ecosystems, regulating sediment storage and transport, consequently determining channel morphology, and as an important foundation for aquatic habitat. LW occurs as either individual pieces or in accumulations (log jams). Where individual pieces of LW affect the stream at a small scale, several bankfull widths, jams influence the stream on a much larger scale. The spatial extent of jam related effects on channel morphology vary, dependent upon the life stage of the jam. Temporal changes in jams have received relatively little attention in the literature. The development stage of a jam is associated with upstream channel aggradation and downstream degradation; this process reverses during a jam's deterioration phase. Carnation Creek, an 11 km2 watershed located on the west coast of Vancouver Island, provided a rare opportunity to examine both the spatial and temporal impacts of log jams on channel morphology. An understanding of these relationships will be developed through the analysis of changes in channel variables, such as channel dimensions, pattern, hydraulic characteristics, and morphology. These characteristics will be extracted from annual cross sectional surveys taken during 1971 - 1998.

  5. Molecular cloning of a K+ channel from the malaria parasite Plasmodium falciparum

    DEFF Research Database (Denmark)

    Ellekvist, Peter; Ricke, Christina Høier; Litman, Thomas

    2004-01-01

    In most living cells, K(+) channels are important for the generation of the membrane potential and for volume regulation. The parasite Plasmodium falciparum, which causes malignant malaria, must be able to deal with large variations in the ambient K(+) concentration: it is exposed to high...... concentrations of K(+) when inside the erythrocyte and low concentrations when in plasma. In the recently published genome of P. falciparum, we have identified a gene, pfkch1, encoding a potential K(+) channel, which to some extent resembles the big-conductance (BK) K(+) channel. We have cloned the approximately...

  6. β1 subunit stabilises sodium channel Nav1.7 against mechanical stress.

    Science.gov (United States)

    Körner, Jannis; Meents, Jannis; Machtens, Jan-Philipp; Lampert, Angelika

    2018-06-01

    The voltage-gated sodium channel Nav1.7 is a key player in neuronal excitability and pain signalling. In addition to voltage sensing, the channel is also modulated by mechanical stress. Using whole-cell patch-clamp experiments, we discovered that the sodium channel subunit β1 is able to prevent the impact of mechanical stress on Nav1.7. An intramolecular disulfide bond of β1 was identified to be essential for stabilisation of inactivation, but not activation, against mechanical stress using molecular dynamics simulations, homology modelling and site-directed mutagenesis. Our results highlight the role of segment 6 of domain IV in fast inactivation. We present a candidate mechanism for sodium channel stabilisation against mechanical stress, ensuring reliable channel functionality in living systems. Voltage-gated sodium channels are key players in neuronal excitability and pain signalling. Precise gating of these channels is crucial as even small functional alterations can lead to pathological phenotypes such as pain or heart failure. Mechanical stress has been shown to affect sodium channel activation and inactivation. This suggests that stabilising components are necessary to ensure precise channel gating in living organisms. Here, we show that mechanical shear stress affects voltage dependence of activation and fast inactivation of the Nav1.7 channel. Co-expression of the β1 subunit, however, protects both gating modes of Nav1.7 against mechanical shear stress. Using molecular dynamics simulation, homology modelling and site-directed mutagenesis, we identify an intramolecular disulfide bond of β1 (Cys21-Cys43) which is partially involved in this process: the β1-C43A mutant prevents mechanical modulation of voltage dependence of activation, but not of fast inactivation. Our data emphasise the unique role of segment 6 of domain IV for sodium channel fast inactivation and confirm previous reports that the intracellular process of fast inactivation can be

  7. Water removal characteristics of parallel serpentine channels

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, K.; Zhou, B.; Quan, P. [Windsor Univ., ON (Canada). Dept. of Mechanical, Automotive and Materials Engineering

    2005-07-01

    A study was conducted in which the liquid water behaviours in parallel serpentine channels with manifolds on the cathode side of a proton exchange membrane (PEM) fuel cell stack were examined. A 3-dimensional, unsteady two-phase flow model within the commercial computational fluid dynamics software package FLUENT was used. Membrane electrode assemblies (MEA) were placed on different sides in the numerical analysis. Several water management issues were identified for this type of fuel cell stack by examining the flow behaviours of liquid water and airflow velocity fields. It was shown that water in the outflow manifold could be blocked by air streams from the gas flow channels, with water flowing continuously into the outflow manifold. It was also shown that the pressure drop along all the unit cells can never increase or decrease at the same pace. Water which adheres to the end wall of both the inlet and outlet manifolds is difficult to remove. It was suggested that faster water drainage can be achieved by keeping the MEA side of the gas flow channels close to the outlet of the outflow manifold. It was also suggested that the collecting and separating effect at the serpentine gas flow channels could improve the water drainage. 8 refs., 10 figs.

  8. A channel profile analyser

    International Nuclear Information System (INIS)

    Gobbur, S.G.

    1983-01-01

    It is well understood that due to the wide band noise present in a nuclear analog-to-digital converter, events at the boundaries of adjacent channels are shared. It is a difficult and laborious process to exactly find out the shape of the channels at the boundaries. A simple scheme has been developed for the direct display of channel shape of any type of ADC on a cathode ray oscilliscope display. This has been accomplished by sequentially incrementing the reference voltage of a precision pulse generator by a fraction of a channel and storing ADC data in alternative memory locations of a multichannel pulse height analyser. Alternative channels are needed due to the sharing at the boundaries of channels. In the flat region of the profile alternate memory locations are channels with zero counts and channels with the full scale counts. At the boundaries all memory locations will have counts. The shape of this is a direct display of the channel boundaries. (orig.)

  9. Insight into DEG/ENaC channel gating from genetics and structure.

    Science.gov (United States)

    Eastwood, Amy L; Goodman, Miriam B

    2012-10-01

    The founding members of the superfamily of DEG/ENaC ion channel proteins are C. elegans proteins that form mechanosensitive channels in touch and pain receptors. For more than a decade, the research community has used mutagenesis to identify motifs that regulate gating. This review integrates insight derived from unbiased in vivo mutagenesis screens with recent crystal structures to develop new models for activation of mechanically gated DEGs.

  10. Learning in the machine: The symmetries of the deep learning channel.

    Science.gov (United States)

    Baldi, Pierre; Sadowski, Peter; Lu, Zhiqin

    2017-11-01

    In a physical neural system, learning rules must be local both in space and time. In order for learning to occur, non-local information must be communicated to the deep synapses through a communication channel, the deep learning channel. We identify several possible architectures for this learning channel (Bidirectional, Conjoined, Twin, Distinct) and six symmetry challenges: (1) symmetry of architectures; (2) symmetry of weights; (3) symmetry of neurons; (4) symmetry of derivatives; (5) symmetry of processing; and (6) symmetry of learning rules. Random backpropagation (RBP) addresses the second and third symmetry, and some of its variations, such as skipped RBP (SRBP) address the first and the fourth symmetry. Here we address the last two desirable symmetries showing through simulations that they can be achieved and that the learning channel is particularly robust to symmetry variations. Specifically, random backpropagation and its variations can be performed with the same non-linear neurons used in the main input-output forward channel, and the connections in the learning channel can be adapted using the same algorithm used in the forward channel, removing the need for any specialized hardware in the learning channel. Finally, we provide mathematical results in simple cases showing that the learning equations in the forward and backward channels converge to fixed points, for almost any initial conditions. In symmetric architectures, if the weights in both channels are small at initialization, adaptation in both channels leads to weights that are essentially symmetric during and after learning. Biological connections are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Automatic detection and classification of artifacts in single-channel EEG

    DEFF Research Database (Denmark)

    Olund, Thomas; Duun-Henriksen, Jonas; Kjaer, Troels W.

    2014-01-01

    Ambulatory EEG monitoring can provide medical doctors important diagnostic information, without hospitalizing the patient. These recordings are however more exposed to noise and artifacts compared to clinically recorded EEG. An automatic artifact detection and classification algorithm for single......-channel EEG is proposed to help identifying these artifacts. Features are extracted from the EEG signal and wavelet subbands. Subsequently a selection algorithm is applied in order to identify the best discriminating features. A non-linear support vector machine is used to discriminate among different...... artifact classes using the selected features. Single-channel (Fp1-F7) EEG recordings are obtained from experiments with 12 healthy subjects performing artifact inducing movements. The dataset was used to construct and validate the model. Both subject-specific and generic implementation, are investigated...

  12. Voltage-dependent gating in a "voltage sensor-less" ion channel.

    Directory of Open Access Journals (Sweden)

    Harley T Kurata

    2010-02-01

    Full Text Available The voltage sensitivity of voltage-gated cation channels is primarily attributed to conformational changes of a four transmembrane segment voltage-sensing domain, conserved across many levels of biological complexity. We have identified a remarkable point mutation that confers significant voltage dependence to Kir6.2, a ligand-gated channel that lacks any canonical voltage-sensing domain. Similar to voltage-dependent Kv channels, the Kir6.2[L157E] mutant exhibits time-dependent activation upon membrane depolarization, resulting in an outwardly rectifying current-voltage relationship. This voltage dependence is convergent with the intrinsic ligand-dependent gating mechanisms of Kir6.2, since increasing the membrane PIP2 content saturates Po and eliminates voltage dependence, whereas voltage activation is more dramatic when channel Po is reduced by application of ATP or poly-lysine. These experiments thus demonstrate an inherent voltage dependence of gating in a "ligand-gated" K+ channel, and thereby provide a new view of voltage-dependent gating mechanisms in ion channels. Most interestingly, the voltage- and ligand-dependent gating of Kir6.2[L157E] is highly sensitive to intracellular [K+], indicating an interaction between ion permeation and gating. While these two key features of channel function are classically dealt with separately, the results provide a framework for understanding their interaction, which is likely to be a general, if latent, feature of the superfamily of cation channels.

  13. Identification of potential novel interaction partners of the sodium-activated potassium channels Slick and Slack in mouse brain.

    Science.gov (United States)

    Rizzi, Sandra; Schwarzer, Christoph; Kremser, Leopold; Lindner, Herbert H; Knaus, Hans-Günther

    2015-12-01

    The sodium-activated potassium channels Slick (Slo2.1, KCNT2) and Slack (Slo2.2, KCNT1) are paralogous channels of the Slo family of high-conductance potassium channels. Slick and Slack channels are widely distributed in the mammalian CNS and they play a role in slow afterhyperpolarization, generation of depolarizing afterpotentials and in setting and stabilizing the resting potential. In the present study we used a combined approach of (co)-immunoprecipitation studies, Western blot analysis, double immunofluorescence and mass spectrometric sequencing in order to investigate protein-protein interactions of the Slick and Slack channels. The data strongly suggest that Slick and Slack channels co-assemble into identical cellular complexes. Double immunofluorescence experiments revealed that Slick and Slack channels co-localize in distinct mouse brain regions. Moreover, we identified the small cytoplasmic protein beta-synuclein and the transmembrane protein 263 (TMEM 263) as novel interaction partners of both, native Slick and Slack channels. In addition, the inactive dipeptidyl-peptidase (DPP 10) and the synapse associated protein 102 (SAP 102) were identified as constituents of the native Slick and Slack channel complexes in the mouse brain. This study presents new insights into protein-protein interactions of native Slick and Slack channels in the mouse brain.

  14. Purification and subunit structure of a putative K+-channel protein identified by its binding properties for dendrotoxin I

    International Nuclear Information System (INIS)

    Rehm, H.; Lazdunski, M.

    1988-01-01

    The binding protein for the K + -channel toxin dendrotoxin I was purified from a detergent extract of rat brain membranes. The purification procedure utilized chromatography on DEAE-Trisacryl, affinity chromatography on a dendrotoxin-I-Aca 22 column, and wheat germ agglutinin-Affigel 10 with a final 3,800- to 4,600-fold enrichment and a recovery of 8-16%. The high affinity (K d , 40-100 pM) and specificity of the binding site are retained throughout the purification procedure. Analysis of the purified material on silver-stained NaDodSO 4 /polyacrylamide gel revealed three bands of M r 76,000-80,000, 38,000 and 35,000. Interestingly, the binding site for 125 I-labeled mast cell degranulating peptide, another putative K + -channel ligand from bee venom, which induces long-term potentiation in hippocampus, seems to reside on the same protein complex, as both binding sites copurify through the entire purification protocol

  15. Pannexin-1 channels show distinct morphology and no gap junction characteristics in mammalian cells.

    Science.gov (United States)

    Beckmann, Anja; Grissmer, Alexander; Krause, Elmar; Tschernig, Thomas; Meier, Carola

    2016-03-01

    Pannexins (Panx) are proteins with a similar membrane topology to connexins, the integral membrane protein of gap junctions. Panx1 channels are generally of major importance in a large number of system and cellular processes and their function has been thoroughly characterized. In contrast, little is known about channel structure and subcellular distribution. We therefore determine the subcellular localization of Panx1 channels in cultured cells and aim at the identification of channel morphology in vitro. Using freeze-fracture replica immunolabeling on EYFP-Panx1-overexpressing HEK 293 cells, large particles were identified in plasma membranes, which were immunogold-labeled using either GFP or Panx1 antibodies. There was no labeling or particles in the nuclear membranes of these cells, pointing to plasma membrane localization of Panx1-EYFP channels. The assembly of particles was irregular, this being in contrast to the regular pattern of gap junctions. The fact that no counterparts were identified on apposing cells, which would have been indicative of intercellular signaling, supported the idea of Panx1 channels within one membrane. Control cells (transfected with EYFP only, non-transfected) were devoid of both particles and immunogold labeling. Altogether, this study provides the first demonstration of Panx1 channel morphology and assembly in intact cells. The identification of Panx1 channels as large particles within the plasma membrane provides the knowledge required to enable recognition of Panx1 channels in tissues in future studies. Thus, these results open up new avenues for the detailed analysis of the subcellular localization of Panx1 and of its nearest neighbors such as purinergic receptors in vivo.

  16. Assembly of the epithelial Na+ channel evaluated using sucrose gradient sedimentation analysis.

    Science.gov (United States)

    Cheng, C; Prince, L S; Snyder, P M; Welsh, M J

    1998-08-28

    Three subunits, alpha, beta, and gamma, contribute to the formation of the epithelial Na+ channel. To investigate the oligomeric assembly of the channel complex, we used sucrose gradient sedimentation analysis to determine the sedimentation properties of individual subunits and heteromultimers comprised of multiple subunits. When the alpha subunit was expressed alone, it first formed an oligomeric complex with a sedimentation coefficient of 11 S, and then generated a higher order multimer of 25 S. In contrast, individual beta and gamma subunits predominately assembled into 11 S complexes. We obtained similar results with expression in cells and in vitro. When we co-expressed beta with alpha or with alpha plus gamma, the beta subunit assembled into a 25 S complex. Glycosylation of the alpha subunit was not required for assembly into a 25 S complex. We found that the alpha subunit formed intra-chain disulfide bonds. Although such bonds were not required to generate an oligomeric complex, under nonreducing conditions the alpha subunit formed a complex that migrated more homogeneously at 25 S. This suggests that intra-chain disulfide bonds may stabilize the complex. These data suggest that the epithelial Na+ channel subunits form high order oligomeric complexes and that the alpha subunit contains the information that facilitates such formation. Interestingly, the ability of the alpha, but not the beta or gamma, subunit to assemble into a 25 S homomeric complex correlates with the ability of these subunits to generate functional channels when expressed alone.

  17. Channel and Timeslot Co-Scheduling with Minimal Channel Switching for Data Aggregation in MWSNs

    Directory of Open Access Journals (Sweden)

    Sanggil Yeoum

    2017-05-01

    Full Text Available Collision-free transmission and efficient data transfer between nodes can be achieved through a set of channels in multichannel wireless sensor networks (MWSNs. While using multiple channels, we have to carefully consider channel interference, channel and time slot (resources optimization, channel switching delay, and energy consumption. Since sensor nodes operate on low battery power, the energy consumed in channel switching becomes an important challenge. In this paper, we propose channel and time slot scheduling for minimal channel switching in MWSNs, while achieving efficient and collision-free transmission between nodes. The proposed scheme constructs a duty-cycled tree while reducing the amount of channel switching. As a next step, collision-free time slots are assigned to every node based on the minimal data collection delay. The experimental results demonstrate that the validity of our scheme reduces the amount of channel switching by 17.5%, reduces energy consumption for channel switching by 28%, and reduces the schedule length by 46%, as compared to the existing schemes.

  18. The structure of a conserved Piezo channel domain reveals a novel beta sandwich fold

    Science.gov (United States)

    Kamajaya, Aron; Kaiser, Jens; Lee, Jonas; Reid, Michelle; Rees, Douglas C.

    2014-01-01

    Summary Piezo has recently been identified as a family of eukaryotic mechanosensitive channels composed of subunits containing over 2000 amino acids, without recognizable sequence similarity to other channels. Here, we present the crystal structure of a large, conserved extramembrane domain located just before the last predicted transmembrane helix of C. elegans PIEZO, which adopts a novel beta sandwich fold. The structure was also determined of a point mutation located on a conserved surface at the position equivalent to the human PIEZO1 mutation found in Dehydrated Hereditary Stomatocytosis (DHS) patients (M2225R). While the point mutation does not change the overall domain structure, it does alter the surface electrostatic potential that may perturb interactions with a yet-to-be identified ligand or protein. The lack of structural similarity between this domain and any previously characterized fold, including those of eukaryotic and bacterial channels, highlights the distinctive nature of the Piezo family of eukaryotic mechanosensitive channels. PMID:25242456

  19. Surface channeling

    International Nuclear Information System (INIS)

    Sizmann, R.; Varelas, C.

    1976-01-01

    There is experimental evidence that swift light ions incident at small angles towards single crystalline surfaces can lose an appreciable fraction of their kinetic energy during reflection. It is shown that these projectiles penetrate into the bulk surface region of the crystal. They can travel as channeled particles along long paths through the solid (surface channeling). The angular distribution and the depth history of the re-emerged projectiles are investigated by computer simulations. A considerable fraction of the penetrating projectiles re-emerges from the crystal with constant transverse energy if the angle of incidence is smaller than the critical angle for axial channeling. Analytical formulae are derived based on a diffusion model for surface channeling. A comparison with experimental data exhibits the relevance of the analytical solutions. (Auth.)

  20. Study of multi-channel readout ASIC and its discrete module for particle detector

    International Nuclear Information System (INIS)

    Wang Ke; Fan Lei; Zhang Shengjun; Li Xian

    2013-01-01

    Recently, kinds of particle detectors have used Application Specific Integrated Circuits (ASIC) in their electronics readout systems, it is the key part for the whole system. This project designed a multi-channel readout ASIC for general detectors. The chip has Preamplifier, Shaper and Peak Detector embedded for easy readout. For each channel, signal which is preprocessed by a low-noise preamplifier is sent to the shaper to form a quasi-Gaussian pulse and keep its peak for readout. This chip and modules of individual Preamplifier, Shaper and Peak Detector have been manufactured and tested. The discrete modules work well, and the 6-channel chip NPRE 6 is ready for test in some particle detection system. (authors)

  1. Even distribution/dividing of single-phase fluids by symmetric bifurcation of flow channels

    International Nuclear Information System (INIS)

    Liu, Hong; Li, Peiwen

    2013-01-01

    Highlights: ► We addressed an issue of distributing a flow to a number of flow channels uniformly. ► The flow distribution is accomplished through bifurcation of channels. ► Some key parameters to the flow distribution uniformity have been identified. ► Flow uniformity was studied for several versions of flow distributor designs. ► A novel fluid packaging device of high efficiency was provided. -- Abstract: This study addresses a fundamental issue of distributing a single-phase fluid flow into a number of flow channels uniformly. A basic mechanism of flow distribution is accomplished through bifurcation of channels that symmetrically split one flow channel into two downstream channels. Applying the basic mechanism, cascades flow distributions are designed to split one flow into a large number of downstream flows uniformly. Some key parameters decisive to the flow distribution uniformity in such a system have been identified, and the flow distribution uniformity of air was studied for several versions of flow distributor designs using CFD analysis. The effect of the key parameters of the flow channel designs to the flow distribution uniformity was investigated. As an example of industrial application, a novel fluid packaging device of high efficiency was proposed and some CFD analysis results for the device were provided. The optimized flow distributor makes a very good uniform flow distribution which will significantly improve the efficiency of fluid packaging. The technology is expected to be of great significance to many industrial devices that require high uniformity of flow distribution

  2. Expression and distribution of voltage-gated ion channels in ferret sinoatrial node.

    Science.gov (United States)

    Brahmajothi, Mulugu V; Morales, Michael J; Campbell, Donald L; Steenbergen, Charles; Strauss, Harold C

    2010-10-01

    Spontaneous diastolic depolarization in the sinoatrial (SA) node enables it to serve as pacemaker of the heart. The variable cell morphology within the SA node predicts that ion channel expression would be heterogeneous and different from that in the atrium. To evaluate ion channel heterogeneity within the SA node, we used fluorescent in situ hybridization to examine ion channel expression in the ferret SA node region and atrial appendage. SA nodal cells were distinguished from surrounding cardiac myocytes by expression of the slow (SA node) and cardiac (surrounding tissue) forms of troponin I. Nerve cells in the sections were identified by detection of GAP-43 and cytoskeletal middle neurofilament. Transcript expression was characterized for the 4 hyperpolarization-activated cation channels, 6 voltage-gated Na(+) channels, 3 voltage-gated Ca(2+) channels, 24 voltage-gated K(+) channel α-subunits, and 3 ancillary subunits. To ensure that transcript expression was representative of protein expression, immunofluorescence was used to verify localization patterns of voltage-dependent K(+) channels. Colocalizations were performed to observe any preferential patterns. Some overlapping and nonoverlapping binding patterns were observed. Measurement of different cation channel transcripts showed heterogeneous expression with many different patterns of expression, attesting to the complexity of electrical activity in the SA node. This study provides insight into the possible role ion channel heterogeneity plays in SA node pacemaker activity.

  3. Sub-Nanometer Channels Embedded in Two-Dimensional Materials

    KAUST Repository

    Han, Yimo

    2017-07-31

    Two-dimensional (2D) materials are among the most promising candidates for next-generation electronics due to their atomic thinness, allowing for flexible transparent electronics and ultimate length scaling1. Thus far, atomically-thin p-n junctions2-7, metal-semiconductor contacts8-10, and metal-insulator barriers11-13 have been demonstrated. While 2D materials achieve the thinnest possible devices, precise nanoscale control over the lateral dimensions are also necessary. Although external one-dimensional (1D) carbon nanotubes14 can be used to locally gate 2D materials, this adds a non-trivial third dimension, complicating device integration and flexibility. Here, we report the direct synthesis of sub-nanometer 1D MoS2 channels embedded within WSe2 monolayers, using a dislocation-catalyzed approach. The 1D channels have edges free of misfit dislocations and dangling bonds, forming a coherent interface with the embedding 2D matrix. Periodic dislocation arrays produce 2D superlattices of coherent MoS2 1D channels in WSe2. Molecular dynamics (MD) simulations have identified other combinations of 2D materials that could form 1D channels. Density function theory (DFT) calculation predicts these 1D channels display type II band alignment needed for carrier confinement and charge separation to access the ultimate length scales necessary for future electronic applications.

  4. Beyond voltage-gated ion channels: Voltage-operated membrane proteins and cellular processes.

    Science.gov (United States)

    Zhang, Jianping; Chen, Xingjuan; Xue, Yucong; Gamper, Nikita; Zhang, Xuan

    2018-04-18

    Voltage-gated ion channels were believed to be the only voltage-sensitive proteins in excitable (and some non-excitable) cells for a long time. Emerging evidence indicates that the voltage-operated model is shared by some other transmembrane proteins expressed in both excitable and non-excitable cells. In this review, we summarize current knowledge about voltage-operated proteins, which are not classic voltage-gated ion channels as well as the voltage-dependent processes in cells for which single voltage-sensitive proteins have yet to be identified. Particularly, we will focus on the following. (1) Voltage-sensitive phosphoinositide phosphatases (VSP) with four transmembrane segments homologous to the voltage sensor domain (VSD) of voltage-gated ion channels; VSPs are the first family of proteins, other than the voltage-gated ion channels, for which there is sufficient evidence for the existence of the VSD domain; (2) Voltage-gated proton channels comprising of a single voltage-sensing domain and lacking an identified pore domain; (3) G protein coupled receptors (GPCRs) that mediate the depolarization-evoked potentiation of Ca 2+ mobilization; (4) Plasma membrane (PM) depolarization-induced but Ca 2+ -independent exocytosis in neurons. (5) Voltage-dependent metabolism of phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P 2 , PIP 2 ) in the PM. These recent discoveries expand our understanding of voltage-operated processes within cellular membranes. © 2018 Wiley Periodicals, Inc.

  5. LRRK2 regulates voltage-gated calcium channel function.

    Directory of Open Access Journals (Sweden)

    Cade eBedford

    2016-05-01

    Full Text Available Voltage-gated Ca2+ (CaV channels enable Ca2+ influx in response to membrane depolarization. CaV2.1 channels are localized to the presynaptic membrane of many types of neurons where they are involved in triggering neurotransmitter release. Several signaling proteins have been identified as important CaV2.1 regulators including protein kinases, G-proteins and Ca2+ binding proteins. Recently, we discovered that leucine rich repeat kinase 2 (LRRK2, a protein associated with inherited Parkinson’s disease, interacts with specific synaptic proteins and influences synaptic transmission. Since synaptic proteins functionally interact with CaV2.1 channels and synaptic transmission is triggered by Ca2+ entry via CaV2.1, we investigated whether LRRK2 could impact CaV2.1 channel function. CaV2.1 channel properties were measured using whole cell patch clamp electrophysiology in HEK293 cells transfected with CaV2.1 subunits and various LRRK2 constructs. Our results demonstrate that both wild type LRRK2 and the G2019S LRRK2 mutant caused a significant increase in whole cell Ca2+ current density compared to cells expressing only the CaV2.1 channel complex. In addition, LRRK2 expression caused a significant hyperpolarizing shift in voltage-dependent activation while having no significant effect on inactivation properties. These functional changes in CaV2.1 activity are likely due to a direct action of LRRK2 as we detected a physical interaction between LRRK2 and the β3 CaV channel subunit via coimmunoprecipitation. Furthermore, effects on CaV2.1 channel function are dependent on LRRK2 kinase activity as these could be reversed via treatment with a LRRK2 inhibitor. Interestingly, LRRK2 also augmented endogenous voltage-gated Ca2+ channel function in PC12 cells suggesting other CaV channels could also be regulated by LRRK2. Overall, our findings support a novel physiological role for LRRK2 in regulating CaV2.1 function that could have implications for how

  6. Structure-based assessment of disease-related mutations in human voltage-gated sodium channels

    Directory of Open Access Journals (Sweden)

    Weiyun Huang

    2017-02-01

    Full Text Available ABSTRACT Voltage-gated sodium (Nav channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Nav channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Nav channels, with Nav1.1 and Nav1.5 each harboring more than 400 mutations. Nav channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Nav channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Cav channel Cav1.1 provides a template for homology-based structural modeling of the evolutionarily related Nav channels. In this Resource article, we summarized all the reported disease-related mutations in human Nav channels, generated a homologous model of human Nav1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Nav channels, the analysis presented here serves as the base framework for mechanistic investigation of Nav channelopathies and for potential structure-based drug discovery.

  7. Structure-based assessment of disease-related mutations in human voltage-gated sodium channels.

    Science.gov (United States)

    Huang, Weiyun; Liu, Minhao; Yan, S Frank; Yan, Nieng

    2017-06-01

    Voltage-gated sodium (Na v ) channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Na v channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Na v channels, with Na v 1.1 and Na v 1.5 each harboring more than 400 mutations. Na v channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Na v channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Ca v ) channel Ca v 1.1 provides a template for homology-based structural modeling of the evolutionarily related Na v channels. In this Resource article, we summarized all the reported disease-related mutations in human Na v channels, generated a homologous model of human Na v 1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Na v channels, the analysis presented here serves as the base framework for mechanistic investigation of Na v channelopathies and for potential structure-based drug discovery.

  8. Channels of health communications used among Korean and Asian Indian older adults.

    Science.gov (United States)

    Lee, Ji Seon

    2010-01-01

    According to Healthy People 2010, health communication is an important tool to reduce health disparities. Communication channels in which people prefer to receive health information may differ by race/ethnicity. One of the main challenges in designing an effective health communication program is to identify the most trusted and most often used channels of health information by Asian older adults. The aim of this study is to determine which health communication channels can be used to promote healthy lifestyles among older adults. A non-probability, convenience-sampling technique was used to recruit Korean (n = 9) and Asian Indian (n = 9) older adults from two senior centers in New York City. The findings from the two focus groups identified three distinct channels used by Asian older adults when obtaining health information: interpersonal (i.e., health care providers, word of mouth), mass media (i.e., ethnic mass media sources), and community specific (i.e., religious organizations, community centers). Health communication is an important area for prevention. Increased efforts are needed to develop culturally appropriate health messages and equally important to deliver these messages in the context in which Asian older adults trust and use the most.

  9. Experimental evidence of independence of nuclear de-channeling length on the particle charge sign

    Energy Technology Data Exchange (ETDEWEB)

    Bagli, E.; Guidi, V.; Mazzolari, A.; Bandiera, L.; Germogli, G.; Sytov, A.I. [Universita di Ferrara, Dipartimento di Fisica e Scienze della Terra (Italy); INFN Sezione di Ferrara (Italy); De Salvador, D. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); INFN Laboratori Nazionali di Legnaro (Italy); Berra, A.; Prest, M. [Universita dell' Insubria, Como (Italy); INFN Sezione di Milano Bicocca, Milan (Italy); Vallazza, E. [INFN Sezione di Trieste (Italy)

    2017-02-15

    Under coherent interactions, particles undergo correlated collisions with the crystal lattice and their motion result in confinement in the fields of atomic planes, i.e. particle channeling. Other than coherently interacting with the lattice, particles also suffer incoherent interactions with individual nuclei and may leave their bounded motion, i.e., they de-channel. The latter is the main limiting factor for applications of coherent interactions in crystal-assisted particle steering. We experimentally investigated the nature of de-channeling of 120 GeV/c e{sup -} and e{sup +} in a bent silicon crystal at H4-SPS external line at CERN. We found that while channeling efficiency differs significantly for e{sup -} (2 ± 2%) and e{sup +} (54 ± 2%), their nuclear de-channeling length is comparable, (0.6 ± 0.1) mm for e{sup -} and (0.7 ± 0.3) mm for e{sup +}. The experimental proof of the equality of the nuclear de-channeling length for positrons and electrons is interpreted in terms of similar dynamics undergone by the channeled particles in the field of nuclei irrespective of their charge. (orig.)

  10. An information-guided channel-hopping scheme for block-fading channels with estimation errors

    KAUST Repository

    Yang, Yuli

    2010-12-01

    Information-guided channel-hopping technique employing multiple transmit antennas was previously proposed for supporting high data rate transmission over fading channels. This scheme achieves higher data rates than some mature schemes, such as the well-known cyclic transmit antenna selection and space-time block coding, by exploiting the independence character of multiple channels, which effectively results in having an additional information transmitting channel. Moreover, maximum likelihood decoding may be performed by simply decoupling the signals conveyed by the different mapping methods. In this paper, we investigate the achievable spectral efficiency of this scheme in the case of having channel estimation errors, with optimum pilot overhead for minimum meansquare error channel estimation, when transmitting over blockfading channels. Our numerical results further substantiate the robustness of the presented scheme, even with imperfect channel state information. ©2010 IEEE.

  11. ASIC3 Channels Integrate Agmatine and Multiple Inflammatory Signals through the Nonproton Ligand Sensing Domain

    Directory of Open Access Journals (Sweden)

    Cao Hui

    2010-12-01

    Full Text Available Abstract Background Acid-sensing ion channels (ASICs have long been known to sense extracellular protons and contribute to sensory perception. Peripheral ASIC3 channels represent natural sensors of acidic and inflammatory pain. We recently reported the use of a synthetic compound, 2-guanidine-4-methylquinazoline (GMQ, to identify a novel nonproton sensing domain in the ASIC3 channel, and proposed that, based on its structural similarity with GMQ, the arginine metabolite agmatine (AGM may be an endogenous nonproton ligand for ASIC3 channels. Results Here, we present further evidence for the physiological correlation between AGM and ASIC3. Among arginine metabolites, only AGM and its analog arcaine (ARC activated ASIC3 channels at neutral pH in a sustained manner similar to GMQ. In addition to the homomeric ASIC3 channels, AGM also activated heteromeric ASIC3 plus ASIC1b channels, extending its potential physiological relevance. Importantly, the process of activation by AGM was highly sensitive to mild acidosis, hyperosmolarity, arachidonic acid (AA, lactic acid and reduced extracellular Ca2+. AGM-induced ASIC3 channel activation was not through the chelation of extracellular Ca2+ as occurs with increased lactate, but rather through a direct interaction with the newly identified nonproton ligand sensing domain. Finally, AGM cooperated with the multiple inflammatory signals to cause pain-related behaviors in an ASIC3-dependent manner. Conclusions Nonproton ligand sensing domain might represent a novel mechanism for activation or sensitization of ASIC3 channels underlying inflammatory pain-sensing under in vivo conditions.

  12. Update on the implication of potassium channels in autism: K+ channelautism spectrum disorder

    Directory of Open Access Journals (Sweden)

    Luca eGuglielmi

    2015-03-01

    Full Text Available Autism spectrum disorders (ASDs are characterized by impaired ability to properly implement environmental stimuli that are essential to achieve a state of social and cultural exchange. Indeed, the main features of ASD are impairments of interpersonal relationships, verbal and non-verbal communication and restricted and repetitive behaviors. These aspects are often accompanied by several comorbidities such as motor delay, praxis impairment, gait abnormalities, insomnia and above all epilepsy. Genetic analyses of autistic individuals uncovered deleterious mutations in several K+ channel types strengthening the notion that their intrinsic dysfunction may play a central etiologic role in ASD. However, indirect implication of K+ channels in ASD has been also reported. For instance, loss of fragile X mental retardation protein (FMRP results in K+ channels deregulation, network dysfunction and ASD-like cognitive and behavioral symptoms. Therefore, this review provides an update on direct and indirect implications of K+ channels in ASDs. Owing to a mounting body of evidence associating a channelopathy pathogenesis to autism and that nearly 500 ion channel proteins are encoded by the human genome, we also propose to classify ASDs − whose susceptibility is significantly enhanced by ion channels defects, either in a monogenic or multigenic condition − in a new category named channelAutism Spectrum Disorder (channelASD; cASD and introduce a new taxonomy (e.g.: Kvx.y-channelASD and likewise Navx.y-channelASD, Cavx.y-channelASD; etc.. This review also highlights some degree of clinical and genetic overlap between K+ channelASDs and K+ channelepsies, whereby such correlation suggests that a subcategory characterized by a channelASD-channelepsy phenotype may be distinguished. Ultimately, this overview aims to further understand the different clinical subgroups and help parse out the distinct biological basis of autism that are essential to establish patient

  13. Hand Motion Classification Using a Multi-Channel Surface Electromyography Sensor

    Directory of Open Access Journals (Sweden)

    Dong Sun

    2012-01-01

    Full Text Available The human hand has multiple degrees of freedom (DOF for achieving high-dexterity motions. Identifying and replicating human hand motions are necessary to perform precise and delicate operations in many applications, such as haptic applications. Surface electromyography (sEMG sensors are a low-cost method for identifying hand motions, in addition to the conventional methods that use data gloves and vision detection. The identification of multiple hand motions is challenging because the error rate typically increases significantly with the addition of more hand motions. Thus, the current study proposes two new methods for feature extraction to solve the problem above. The first method is the extraction of the energy ratio features in the time-domain, which are robust and invariant to motion forces and speeds for the same gesture. The second method is the extraction of the concordance correlation features that describe the relationship between every two channels of the multi-channel sEMG sensor system. The concordance correlation features of a multi-channel sEMG sensor system were shown to provide a vast amount of useful information for identification. Furthermore, a new cascaded-structure classifier is also proposed, in which 11 types of hand gestures can be identified accurately using the newly defined features. Experimental results show that the success rate for the identification of the 11 gestures is significantly high.

  14. Hand motion classification using a multi-channel surface electromyography sensor.

    Science.gov (United States)

    Tang, Xueyan; Liu, Yunhui; Lv, Congyi; Sun, Dong

    2012-01-01

    The human hand has multiple degrees of freedom (DOF) for achieving high-dexterity motions. Identifying and replicating human hand motions are necessary to perform precise and delicate operations in many applications, such as haptic applications. Surface electromyography (sEMG) sensors are a low-cost method for identifying hand motions, in addition to the conventional methods that use data gloves and vision detection. The identification of multiple hand motions is challenging because the error rate typically increases significantly with the addition of more hand motions. Thus, the current study proposes two new methods for feature extraction to solve the problem above. The first method is the extraction of the energy ratio features in the time-domain, which are robust and invariant to motion forces and speeds for the same gesture. The second method is the extraction of the concordance correlation features that describe the relationship between every two channels of the multi-channel sEMG sensor system. The concordance correlation features of a multi-channel sEMG sensor system were shown to provide a vast amount of useful information for identification. Furthermore, a new cascaded-structure classifier is also proposed, in which 11 types of hand gestures can be identified accurately using the newly defined features. Experimental results show that the success rate for the identification of the 11 gestures is significantly high.

  15. Distribution and function of voltage-gated sodium channels in the nervous system.

    Science.gov (United States)

    Wang, Jun; Ou, Shao-Wu; Wang, Yun-Jie

    2017-11-02

    Voltage-gated sodium channels (VGSCs) are the basic ion channels for neuronal excitability, which are crucial for the resting potential and the generation and propagation of action potentials in neurons. To date, at least nine distinct sodium channel isoforms have been detected in the nervous system. Recent studies have identified that voltage-gated sodium channels not only play an essential role in the normal electrophysiological activities of neurons but also have a close relationship with neurological diseases. In this study, the latest research findings regarding the structure, type, distribution, and function of VGSCs in the nervous system and their relationship to neurological diseases, such as epilepsy, neuropathic pain, brain tumors, neural trauma, and multiple sclerosis, are reviewed in detail.

  16. Charged and Neutral Particles Channeling Phenomena Channeling 2008

    Science.gov (United States)

    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

  17. Serotonin-immunoreactivity in the ventral nerve cord of Pycnogonida--support for individually identifiable neurons as ancestral feature of the arthropod nervous system.

    Science.gov (United States)

    Brenneis, Georg; Scholtz, Gerhard

    2015-07-10

    The arthropod ventral nerve cord features a comparably low number of serotonin-immunoreactive neurons, occurring in segmentally repeated arrays. In different crustaceans and hexapods, these neurons have been individually identified and even inter-specifically homologized, based on their soma positions and neurite morphologies. Stereotypic sets of serotonin-immunoreactive neurons are also present in myriapods, whereas in the investigated chelicerates segmental neuron clusters with higher and variable cell numbers have been reported. This led to the suggestion that individually identifiable serotonin-immunoreactive neurons are an apomorphic feature of the Mandibulata. To test the validity of this neurophylogenetic hypothesis, we studied serotonin-immunoreactivity in three species of Pycnogonida (sea spiders). This group of marine arthropods is nowadays most plausibly resolved as sister group to all other extant chelicerates, rendering its investigation crucial for a reliable reconstruction of arthropod nervous system evolution. In all three investigated pycnogonids, the ventral walking leg ganglia contain different types of serotonin-immunoreactive neurons, the somata of which occurring mostly singly or in pairs within the ganglionic cortex. Several of these neurons are readily and consistently identifiable due to their stereotypic soma position and characteristic neurite morphology. They can be clearly homologized across different ganglia and different specimens as well as across the three species. Based on these homologous neurons, we reconstruct for their last common ancestor (presumably the pycnogonid stem species) a minimal repertoire of at least seven identified serotonin-immunoreactive neurons per hemiganglion. Beyond that, each studied species features specific pattern variations, which include also some neurons that were not reliably labeled in all specimens. Our results unequivocally demonstrate the presence of individually identifiable serotonin

  18. ATP-sensitive K(+-channels in muscle cells: features and physiological role

    Directory of Open Access Journals (Sweden)

    O. B. Vadzyuk

    2014-08-01

    Full Text Available ATP-sensitive K+-channels of plasma membranes belong to the inward rectifier potassium channels type. They are involved in coupling of electrical activity of muscle cell with its metabolic­ state. These channels are heterooctameric and consist of two types of subunits: four poreforming (Kir 6.х and four regulatory (SUR, sulfonylurea receptor. The Kir subunits contain highly selective K+ filter and provide for high-velocity K+ currents. The SUR subunits contain binding sites for activators and blockers and have metabolic sensor, which enables channel activation under conditions of metabolic stress. ATP blocks K+ currents through the ATP-sensitive K+-channels in the most types of muscle cells. However, functional activity of these channels does not depend on absolute concentration of ATP but on the АТР/ADP ratio and presence of Mg2+. Physiologically active substances, such as phosphatidylinositol bisphosphate and fatty acid esters can regulate the activity of these structures in muscle cells. Activation of these channels under ischemic conditions underlies their cytoprotective action, which results in prevention of Ca2+ overload in cytosol. In contrast to ATP-sensitive K+-channels of plasma membranes, the data regarding the structure and function of ATP-sensitive K+-channels of mitochondrial membrane are contradictory. Pore-forming subunits of this channel have not been firmly identified yet. ATP-sensitive K+ transport through the mitochondrial­ membrane is easily tested by different methods, which are briefly reviewed in this paper. Interaction of mitoKATP with physiological and pharmacological ligands is discussed as well.

  19. Crystal structure of the epithelial calcium channel TRPV6.

    Science.gov (United States)

    Saotome, Kei; Singh, Appu K; Yelshanskaya, Maria V; Sobolevsky, Alexander I

    2016-06-23

    Precise regulation of calcium homeostasis is essential for many physiological functions. The Ca(2+)-selective transient receptor potential (TRP) channels TRPV5 and TRPV6 play vital roles in calcium homeostasis as Ca(2+) uptake channels in epithelial tissues. Detailed structural bases for their assembly and Ca(2+) permeation remain obscure. Here we report the crystal structure of rat TRPV6 at 3.25 Å resolution. The overall architecture of TRPV6 reveals shared and unique features compared with other TRP channels. Intracellular domains engage in extensive interactions to form an intracellular 'skirt' involved in allosteric modulation. In the K(+) channel-like transmembrane domain, Ca(2+) selectivity is determined by direct coordination of Ca(2+) by a ring of aspartate side chains in the selectivity filter. On the basis of crystallographically identified cation-binding sites at the pore axis and extracellular vestibule, we propose a Ca(2+) permeation mechanism. Our results provide a structural foundation for understanding the regulation of epithelial Ca(2+) uptake and its role in pathophysiology.

  20. Channel allocation and rate adaptation for relayed transmission over correlated fading channels

    KAUST Repository

    Hwang, Kyusung

    2009-09-01

    We consider, in this paper, channel allocation and rate adaptation scheme for relayed transmission over correlated fading channels via cross-layer design. Specifically, jointly considering the data link layer buffer occupancy and channel quality at both the source and relay nodes, we develop an optimal channel allocation and rate adaptation policy for a dual-hop relayed transmission. As such the overall transmit power for the relayed system is minimized while a target packet dropping rate (PDR) due to buffer over flows is guaranteed. In order to find such an optimal policy, the channel allocation and rate adaptation transmission framework is formulated as a constraint Markov decision process (CMDP). The PDR performance of the optimal policy is compared with that of two conventional suboptimal schemes, namely the channel quality based and the buffer occupancy based channel allocation schemes. Numerical results show that for a given power budget, the optimal scheme requires significantly less power than the conventional schemes in order to maintain a target PDR. ©2009 IEEE.

  1. Analysis of two-phase flow and boiling heat transfer in inclined channel of core-catcher

    International Nuclear Information System (INIS)

    Tahara, M.; Suzuki, Y.; Abe, N.; Kurita, T.; Hamazaki, R.; Kojima, Y.

    2008-01-01

    Passive Corium Cooling System (CCS) provides a function of ex-vessel debris cooling and molten core stabilization during a severe accident. CCS features inclined cooling channels arranged axi-symmetrically below the core-catcher basin. In order to estimate the coolability of the inclined cooling channel, it is indispensable to identify the flow pattern of the two-phase flow in the cooling channel. Several former studies for the two-phase flow pattern in the inclined channel are referred. Taitel and Dukler (1976) developed a prediction method of the flow pattern transition in horizontal and near horizontal tubes. Barnea et al. (1980) showed the flow pattern map of upward flow with 10 degrees inclination. Sakaguti et al. (1996) observed the two-phase flow patterns in the horizontal pipe connected with slightly upward pipe, in which the flow pattern in the pipe with a bending part was expressed by the combination of a basic flow pattern and some auxiliary flow patterns. Then we investigated these studies In order to identify the flow patterns observed in the inclined cooling channel of CCS. Furthermore we experimentally observed the flow patterns in the inclined cooling channel with various inlet conditions. As a result of the investigation and observation, typical flow patterns in the inclined cooling channel were identified. Two typical flow patterns were observed depending on the steam flow rate, one of which is 'elongated bubble 'flow, and the other is 'churn with collapsing backward and upward slug 'flow The flow and heat transfer in the inclined channel of CCS is analyzed by using a two-phase analysis code employing two-fluid model in which the constitutive equations for the two-phase flow in inclined channels are incorporated. That is, drift flux parameter for each of the elongated bubble flow, and the churn with collapsing backward and upward slug flow are incorporated to the two-phase analysis code, which are based on the rising velocity of the long bubble in

  2. The neurobiology of individuality

    Science.gov (United States)

    de Bivort, Benjamin

    2015-03-01

    Individuals often display conspicuously different patterns of behavior, even when they are very closely related genetically. These differences give rise to our sense of individuality, but what is their molecular and neurobiological basis? Individuals that are nominally genetically identical differ at various molecular and neurobiological levels: cell-to-cell variation in somatic genomes, cell-to-cell variation in expression patterns, individual-to-individual variation in neuronal morphology and physiology, and individual-to-individual variation in patterns of brain activity. It is unknown which of these levels is fundamentally causal of behavioral differences. To investigate this problem, we use the fruit fly Drosophila melanogaster, whose genetic toolkit allows the manipulation of each of these mechanistic levels, and whose rapid lifecycle and small size allows for high-throughput automation of behavioral assays. This latter point is crucial; identifying inter-individual behavioral differences requires high sample sizes both within and across individual animals. Automated behavioral characterization is at the heart of our research strategy. In every behavior examined, individual flies have individual behavioral preferences, and we have begun to identify both neural genes and circuits that control the degree of behavioral variability between individuals.

  3. Exome Sequencing Identifies a Novel LMNA Splice-Site Mutation and Multigenic Heterozygosity of Potential Modifiers in a Family with Sick Sinus Syndrome, Dilated Cardiomyopathy, and Sudden Cardiac Death.

    Directory of Open Access Journals (Sweden)

    Michael V Zaragoza

    Full Text Available The goals are to understand the primary genetic mechanisms that cause Sick Sinus Syndrome and to identify potential modifiers that may result in intrafamilial variability within a multigenerational family. The proband is a 63-year-old male with a family history of individuals (>10 with sinus node dysfunction, ventricular arrhythmia, cardiomyopathy, heart failure, and sudden death. We used exome sequencing of a single individual to identify a novel LMNA mutation and demonstrated the importance of Sanger validation and family studies when evaluating candidates. After initial single-gene studies were negative, we conducted exome sequencing for the proband which produced 9 gigabases of sequencing data. Bioinformatics analysis showed 94% of the reads mapped to the reference and identified 128,563 unique variants with 108,795 (85% located in 16,319 genes of 19,056 target genes. We discovered multiple variants in known arrhythmia, cardiomyopathy, or ion channel associated genes that may serve as potential modifiers in disease expression. To identify candidate mutations, we focused on ~2,000 variants located in 237 genes of 283 known arrhythmia, cardiomyopathy, or ion channel associated genes. We filtered the candidates to 41 variants in 33 genes using zygosity, protein impact, database searches, and clinical association. Only 21 of 41 (51% variants were validated by Sanger sequencing. We selected nine confirmed variants with minor allele frequencies G, a novel heterozygous splice-site mutation as the primary mutation with rare or novel variants in HCN4, MYBPC3, PKP4, TMPO, TTN, DMPK and KCNJ10 as potential modifiers and a mechanism consistent with haploinsufficiency.

  4. A Meta-Analysis Identifies New Loci Associated with Body Mass index in Individuals of African Ancestry

    Science.gov (United States)

    Monda, Keri L.; Chen, Gary K.; Taylor, Kira C.; Palmer, Cameron; Edwards, Todd L.; Lange, Leslie A.; Ng, Maggie C.Y.; Adeyemo, Adebowale A.; Allison, Matthew A.; Bielak, Lawrence F.; Chen, Guanji; Graff, Mariaelisa; Irvin, Marguerite R.; Rhie, Suhn K.; Li, Guo; Liu, Yongmei; Liu, Youfang; Lu, Yingchang; Nalls, Michael A.; Sun, Yan V.; Wojczynski, Mary K.; Yanek, Lisa R.; Aldrich, Melinda C.; Ademola, Adeyinka; Amos, Christopher I.; Bandera, Elisa V.; Bock, Cathryn H.; Britton, Angela; Broeckel, Ulrich; Cai, Quiyin; Caporaso, Neil E.; Carlson, Chris; Carpten, John; Casey, Graham; Chen, Wei-Min; Chen, Fang; Chen, Yii-Der I.; Chiang, Charleston W.K.; Coetzee, Gerhard A.; Demerath, Ellen; Deming-Halverson, Sandra L.; Driver, Ryan W.; Dubbert, Patricia; Feitosa, Mary F.; Freedman, Barry I.; Gillanders, Elizabeth M.; Gottesman, Omri; Guo, Xiuqing; Haritunians, Talin; Harris, Tamara; Harris, Curtis C.; Hennis, Anselm JM; Hernandez, Dena G.; McNeill, Lorna H.; Howard, Timothy D.; Howard, Barbara V.; Howard, Virginia J.; Johnson, Karen C.; Kang, Sun J.; Keating, Brendan J.; Kolb, Suzanne; Kuller, Lewis H.; Kutlar, Abdullah; Langefeld, Carl D.; Lettre, Guillaume; Lohman, Kurt; Lotay, Vaneet; Lyon, Helen; Manson, JoAnn E.; Maixner, William; Meng, Yan A.; Monroe, Kristine R.; Morhason-Bello, Imran; Murphy, Adam B.; Mychaleckyj, Josyf C.; Nadukuru, Rajiv; Nathanson, Katherine L.; Nayak, Uma; N’Diaye, Amidou; Nemesure, Barbara; Wu, Suh-Yuh; Leske, M. Cristina; Neslund-Dudas, Christine; Neuhouser, Marian; Nyante, Sarah; Ochs-Balcom, Heather; Ogunniyi, Adesola; Ogundiran, Temidayo O.; Ojengbede, Oladosu; Olopade, Olufunmilayo I.; Palmer, Julie R.; Ruiz-Narvaez, Edward A.; Palmer, Nicholette D.; Press, Michael F.; Rampersaud, Evandine; Rasmussen-Torvik, Laura J.; Rodriguez-Gil, Jorge L.; Salako, Babatunde; Schadt, Eric E.; Schwartz, Ann G.; Shriner, Daniel A.; Siscovick, David; Smith, Shad B.; Wassertheil-Smoller, Sylvia; Speliotes, Elizabeth K.; Spitz, Margaret R.; Sucheston, Lara; Taylor, Herman; Tayo, Bamidele O.; Tucker, Margaret A.; Van Den Berg, David J.; Velez Edwards, Digna R.; Wang, Zhaoming; Wiencke, John K.; Winkler, Thomas W.; Witte, John S.; Wrensch, Margaret; Wu, Xifeng; Yang, James J.; Levin, Albert M.; Young, Taylor R.; Zakai, Neil A.; Cushman, Mary; Zanetti, Krista A.; Zhao, Jing Hua; Zhao, Wei; Zheng, Yonglan; Zhou, Jie; Ziegler, Regina G.; Zmuda, Joseph M.; Fernandes, Jyotika K.; Gilkeson, Gary S.; Kamen, Diane L.; Hunt, Kelly J.; Spruill, Ida J.; Ambrosone, Christine B.; Ambs, Stefan; Arnett, Donna K.; Atwood, Larry; Becker, Diane M.; Berndt, Sonja I.; Bernstein, Leslie; Blot, William J.; Borecki, Ingrid B.; Bottinger, Erwin P.; Bowden, Donald W.; Burke, Gregory; Chanock, Stephen J.; Cooper, Richard S.; Ding, Jingzhong; Duggan, David; Evans, Michele K.; Fox, Caroline; Garvey, W. Timothy; Bradfield, Jonathan P.; Hakonarson, Hakon; Grant, Struan F.A.; Hsing, Ann; Chu, Lisa; Hu, Jennifer J.; Huo, Dezheng; Ingles, Sue A.; John, Esther M.; Jordan, Joanne M.; Kabagambe, Edmond K.; Kardia, Sharon L.R.; Kittles, Rick A.; Goodman, Phyllis J.; Klein, Eric A.; Kolonel, Laurence N.; Le Marchand, Loic; Liu, Simin; McKnight, Barbara; Millikan, Robert C.; Mosley, Thomas H.; Padhukasahasram, Badri; Williams, L. Keoki; Patel, Sanjay R.; Peters, Ulrike; Pettaway, Curtis A.; Peyser, Patricia A.; Psaty, Bruce M.; Redline, Susan; Rotimi, Charles N.; Rybicki, Benjamin A.; Sale, Michèle M.; Schreiner, Pamela J.; Signorello, Lisa B.; Singleton, Andrew B.; Stanford, Janet L.; Strom, Sara S.; Thun, Michael J.; Vitolins, Mara; Zheng, Wei; Moore, Jason H.; Williams, Scott M.; Zhu, Xiaofeng; Zonderman, Alan B.; Kooperberg, Charles; Papanicolaou, George; Henderson, Brian E.; Reiner, Alex P.; Hirschhorn, Joel N.; Loos, Ruth JF; North, Kari E.; Haiman, Christopher A.

    2013-01-01

    Genome-wide association studies (GWAS) have identified 36 loci associated with body mass index (BMI), predominantly in populations of European ancestry. We conducted a meta-analysis to examine the association of >3.2 million SNPs with BMI in 39,144 men and women of African ancestry, and followed up the most significant associations in an additional 32,268 individuals of African ancestry. We identified one novel locus at 5q33 (GALNT10, rs7708584, p=3.4×10−11) and another at 7p15 when combined with data from the Giant consortium (MIR148A/NFE2L3, rs10261878, p=1.2×10−10). We also found suggestive evidence of an association at a third locus at 6q16 in the African ancestry sample (KLHL32, rs974417, p=6.9×10−8). Thirty-two of the 36 previously established BMI variants displayed directionally consistent effect estimates in our GWAS (binomial p=9.7×10−7), of which five reached genome-wide significance. These findings provide strong support for shared BMI loci across populations as well as for the utility of studying ancestrally diverse populations. PMID:23583978

  5. Meta-analysis of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer’s disease

    Science.gov (United States)

    Lambert, Jean-Charles; Ibrahim-Verbaas, Carla A; Harold, Denise; Naj, Adam C; Sims, Rebecca; Bellenguez, Céline; Jun, Gyungah; DeStefano, Anita L; Bis, Joshua C; Beecham, Gary W; Grenier-Boley, Benjamin; Russo, Giancarlo; Thornton-Wells, Tricia A; Jones, Nicola; Smith, Albert V; Chouraki, Vincent; Thomas, Charlene; Ikram, M Arfan; Zelenika, Diana; Vardarajan, Badri N; Kamatani, Yoichiro; Lin, Chiao-Feng; Gerrish, Amy; Schmidt, Helena; Kunkle, Brian; Dunstan, Melanie L; Ruiz, Agustin; Bihoreau, Marie-Thérèse; Choi, Seung-Hoan; Reitz, Christiane; Pasquier, Florence; Hollingworth, Paul; Ramirez, Alfredo; Hanon, Olivier; Fitzpatrick, Annette L; Buxbaum, Joseph D; Campion, Dominique; Crane, Paul K; Baldwin, Clinton; Becker, Tim; Gudnason, Vilmundur; Cruchaga, Carlos; Craig, David; Amin, Najaf; Berr, Claudine; Lopez, Oscar L; De Jager, Philip L; Deramecourt, Vincent; Johnston, Janet A; Evans, Denis; Lovestone, Simon; Letenneur, Luc; Morón, Francisco J; Rubinsztein, David C; Eiriksdottir, Gudny; Sleegers, Kristel; Goate, Alison M; Fiévet, Nathalie; Huentelman, Matthew J; Gill, Michael; Brown, Kristelle; Kamboh, M Ilyas; Keller, Lina; Barberger-Gateau, Pascale; McGuinness, Bernadette; Larson, Eric B; Green, Robert; Myers, Amanda J; Dufouil, Carole; Todd, Stephen; Wallon, David; Love, Seth; Rogaeva, Ekaterina; Gallacher, John; St George-Hyslop, Peter; Clarimon, Jordi; Lleo, Alberto; Bayer, Anthony; Tsuang, Debby W; Yu, Lei; Tsolaki, Magda; Bossù, Paola; Spalletta, Gianfranco; Proitsi, Petroula; Collinge, John; Sorbi, Sandro; Sanchez-Garcia, Florentino; Fox, Nick C; Hardy, John; Deniz Naranjo, Maria Candida; Bosco, Paolo; Clarke, Robert; Brayne, Carol; Galimberti, Daniela; Mancuso, Michelangelo; Matthews, Fiona; Moebus, Susanne; Mecocci, Patrizia; Zompo, Maria Del; Maier, Wolfgang; Hampel, Harald; Pilotto, Alberto; Bullido, Maria; Panza, Francesco; Caffarra, Paolo; Nacmias, Benedetta; Gilbert, John R; Mayhaus, Manuel; Lannfelt, Lars; Hakonarson, Hakon; Pichler, Sabrina; Carrasquillo, Minerva M; Ingelsson, Martin; Beekly, Duane; Alvarez, Victoria; Zou, Fanggeng; Valladares, Otto; Younkin, Steven G; Coto, Eliecer; Hamilton-Nelson, Kara L; Gu, Wei; Razquin, Cristina; Pastor, Pau; Mateo, Ignacio; Owen, Michael J; Faber, Kelley M; Jonsson, Palmi V; Combarros, Onofre; O’Donovan, Michael C; Cantwell, Laura B; Soininen, Hilkka; Blacker, Deborah; Mead, Simon; Mosley, Thomas H; Bennett, David A; Harris, Tamara B; Fratiglioni, Laura; Holmes, Clive; de Bruijn, Renee F A G; Passmore, Peter; Montine, Thomas J; Bettens, Karolien; Rotter, Jerome I; Brice, Alexis; Morgan, Kevin; Foroud, Tatiana M; Kukull, Walter A; Hannequin, Didier; Powell, John F; Nalls, Michael A; Ritchie, Karen; Lunetta, Kathryn L; Kauwe, John S K; Boerwinkle, Eric; Riemenschneider, Matthias; Boada, Mercè; Hiltunen, Mikko; Martin, Eden R; Schmidt, Reinhold; Rujescu, Dan; Wang, Li-san; Dartigues, Jean-François; Mayeux, Richard; Tzourio, Christophe; Hofman, Albert; Nöthen, Markus M; Graff, Caroline; Psaty, Bruce M; Jones, Lesley; Haines, Jonathan L; Holmans, Peter A; Lathrop, Mark; Pericak-Vance, Margaret A; Launer, Lenore J; Farrer, Lindsay A; van Duijn, Cornelia M; Van Broeckhoven, Christine; Moskvina, Valentina; Seshadri, Sudha; Williams, Julie; Schellenberg, Gerard D; Amouyel, Philippe

    2013-01-01

    Eleven susceptibility loci for late-onset Alzheimer’s disease (LOAD) were identified by previous studies; however, a large portion of the genetic risk for this disease remains unexplained. We conducted a large, two-stage meta-analysis of genome-wide association studies (GWAS) in individuals of European ancestry. In stage 1, we used genotyped and imputed data (7,055,881 SNPs) to perform meta-analysis on 4 previously published GWAS data sets consisting of 17,008 Alzheimer’s disease cases and 37,154 controls. In stage 2,11,632 SNPs were genotyped and tested for association in an independent set of 8,572 Alzheimer’s disease cases and 11,312 controls. In addition to the APOE locus (encoding apolipoprotein E), 19 loci reached genome-wide significance (P < 5 × 10−8) in the combined stage 1 and stage 2 analysis, of which 11 are newly associated with Alzheimer’s disease. PMID:24162737

  6. Intracellular trafficking pathways of Cx43 gap junction channels.

    Science.gov (United States)

    Epifantseva, Irina; Shaw, Robin M

    2018-01-01

    Gap Junction (GJ) channels, including the most common Connexin 43 (Cx43), have fundamental roles in excitable tissues by facilitating rapid transmission of action potentials between adjacent cells. For instance, synchronization during each heartbeat is regulated by these ion channels at the cardiomyocyte cell-cell border. Cx43 protein has a short half-life, and rapid synthesis and timely delivery of those proteins to particular subdomains are crucial for the cellular organization of gap junctions and maintenance of intracellular coupling. Impairment in gap junction trafficking contributes to dangerous complications in diseased hearts such as the arrhythmias of sudden cardiac death. Of recent interest are the protein-protein interactions with the Cx43 carboxy-terminus. These interactions have significant impact on the full length Cx43 lifecycle and also contribute to trafficking of Cx43 as well as possibly other functions. We are learning that many of the known non-canonical roles of Cx43 can be attributed to the recently identified six endogenous Cx43 truncated isoforms which are produced by internal translation. In general, alternative translation is a new leading edge for proteome expansion and therapeutic drug development. This review highlights recent mechanisms identified in the trafficking of gap junction channels, involvement of other proteins contributing to the delivery of channels to the cell-cell border, and understanding of possible roles of the newly discovered alternatively translated isoforms in Cx43 biology. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Predictive 3D modelling of the interactions of pyrethroids with the voltage-gated sodium channels of ticks and mites.

    Science.gov (United States)

    O'Reilly, Andrias O; Williamson, Martin S; González-Cabrera, Joel; Turberg, Andreas; Field, Linda M; Wallace, B A; Davies, T G Emyr

    2014-03-01

    The pyrethroid insecticides are a very successful group of compounds that target invertebrate voltage-gated sodium channels and are widely used in the control of insects, ticks and mites. It is well established that some pyrethroids are good insecticides whereas others are more effective as acaricides. This species specificity is advantageous for controlling particular pest(s) in the presence of another non-target invertebrate, for example controlling the Varroa mite in honeybee colonies. We applied in silico techniques to compare the voltage-gated sodium channels of insects versus ticks and mites and their interactions with a range of pyrethroids and DDT analogues. We identified a single amino acid difference within the pyrethroid binding pocket of ticks/mites that may have significant impact on the effectiveness of pyrethroids as acaricides. Other individual amino acid differences within the binding pocket in distinct tick and mite species may provide a basis for future acaricidal selectivity. Three-dimensional modelling of the pyrethroid/DDT receptor site has led to a new hypothesis to explain the preferential binding of acaricidal pyrethroids to the sodium channels of ticks/mites. This is important for understanding pyrethroid selectivity and the potential effects of mutations that can give rise to resistance to pyrethroids in commercially-important pest species. © 2013 Society of Chemical Industry.

  8. Enhancing Electromagnetic Side-Channel Analysis in an Operational Environment

    Science.gov (United States)

    Montminy, David P.

    Side-channel attacks exploit the unintentional emissions from cryptographic devices to determine the secret encryption key. This research identifies methods to make attacks demonstrated in an academic environment more operationally relevant. Algebraic cryptanalysis is used to reconcile redundant information extracted from side-channel attacks on the AES key schedule. A novel thresholding technique is used to select key byte guesses for a satisfiability solver resulting in a 97.5% success rate despite failing for 100% of attacks using standard methods. Two techniques are developed to compensate for differences in emissions from training and test devices dramatically improving the effectiveness of cross device template attacks. Mean and variance normalization improves same part number attack success rates from 65.1% to 100%, and increases the number of locations an attack can be performed by 226%. When normalization is combined with a novel technique to identify and filter signals in collected traces not related to the encryption operation, the number of traces required to perform a successful attack is reduced by 85.8% on average. Finally, software-defined radios are shown to be an effective low-cost method for collecting side-channel emissions in real-time, eliminating the need to modify or profile the target encryption device to gain precise timing information.

  9. Ethanol affects network activity in cultured rat hippocampus: mediation by potassium channels.

    Directory of Open Access Journals (Sweden)

    Eduard Korkotian

    Full Text Available The effects of ethanol on neuronal network activity were studied in dissociated cultures of rat hippocampus. Exposure to low (0.25-0.5% ethanol concentrations caused an increase in synchronized network spikes, and a decrease in the duration of individual spikes. Ethanol also caused an increase in rate of miniature spontaneous excitatory postsynaptic currents. Higher concentrations of ethanol eliminated network spikes. These effects were reversible upon wash. The effects of the high, but not the low ethanol were blocked by the GABA antagonist bicuculline. The enhancing action of low ethanol was blocked by apamin, an SK potassium channel antagonist, and mimicked by 1-EBIO, an SK channel opener. It is proposed that in cultured hippocampal networks low concentration of ethanol is associated with SK channel activity, rather than the GABAergic receptor.

  10. Personalized multi-channel headphone sound reproduction based on active noise cancellation

    NARCIS (Netherlands)

    Schobben, D.W.E.; Aarts, R.M.

    2005-01-01

    A system for headphone signal processing is discussed which gives a listener the same impression as listening to a multi-channel loudspeaker set-up. It is important that this processing is optimized for each individual listener. If this is not the case, large localization errors may occur. In the

  11. New selection criteria for channel refueling of a Candu-6 reactor: introduction to floppy rules

    International Nuclear Information System (INIS)

    Brissette, D.

    2001-01-01

    A revised set of rules is in use at Gentilly-2 NGS for the selection of channels for refuelling. Traditional hard channel rejection rules (of go/no-go type) have been replaced by a more efficient set of soft evaluation rules based on concepts borrowed to the Fuzzy Logic. New evaluation rules, labelled as 'Floppy Rules', enable to assess and rate the channel suitability for refuelling by using a smooth and natural continuum of values qualifying excellent, good, fair and poor choices. Global channel suitability for refuelling is measured by combining separate ratings obtained from individual evaluation rules. Each evaluation rule is based on a specific control parameter related to local or lumped core properties. Two new software codes (NEWRULES and REFUEL) designed around the concept of Floppy Rules enable to perform a very efficient selection of optimized channel refuelling sequences either in manual and automatic mode. (author)

  12. Joint Channel Assignment and Routing in Multiradio Multichannel Wireless Mesh Networks: Design Considerations and Approaches

    Directory of Open Access Journals (Sweden)

    Omar M. Zakaria

    2016-01-01

    Full Text Available Multiradio wireless mesh network is a promising architecture that improves the network capacity by exploiting multiple radio channels concurrently. Channel assignment and routing are underlying challenges in multiradio architectures since both determine the traffic distribution over links and channels. The interdependency between channel assignments and routing promotes toward the joint solutions for efficient configurations. This paper presents an in-depth review of the joint approaches of channel assignment and routing in multiradio wireless mesh networks. First, the key design issues, modeling, and approaches are identified and discussed. Second, existing algorithms for joint channel assignment and routing are presented and classified based on the channel assignment types. Furthermore, the set of reconfiguration algorithms to adapt the network traffic dynamics is also discussed. Finally, the paper presents some multiradio practical implementations and test-beds and points out the future research directions.

  13. Femtosecond laser direct generation of 3D-microfluidic channels inside bulk PMMA.

    Science.gov (United States)

    Roth, Gian-Luca; Esen, Cemal; Hellmann, Ralf

    2017-07-24

    We report on laser direct generation of 3D-microchannels for microfluidic applications inside PMMA bulk material by focused femtosecond pulses. Inner lying channels with cross sectional areas from 100 µm 2 to 4400 µm 2 are directly created in the volume of a PMMA substrate. Using the presented process, the channel length is fundamentally unlimited. Here we demonstrate a channel length of 6 meters inside a substrate with dimensions of 20 × 20 × 1.1 mm. The formation of the micro channels is based on nonlinear absorption around the focal volume that triggers a material modification. The modified volume can be selectively opened to form the channel by a subsequent annealing process. The cross section of the channel is strongly influenced by the energy distribution and illumination around the focal volume determined by the optical setup and process design. The 3D channel layout can easily be realized by moving the specimen using 3D motorized stage, allowing freely chosen complex shaped channel architectures. Within a comprehensive parameter study, varying laser power, number of multi-passes, writing speed and writing depths, we identify an optimized process in terms of attainable channel height, width and aspect ratio, as well as process stability and reproducibility. The proof of concept for an application in three dimensional microfluidic systems is provided by florescence microscopy using a dye rhodamine B solution in isopropanol.

  14. On the secrecy capacity of the MISO wiretap channel under imperfect channel estimation

    KAUST Repository

    Rezki, Zouheir; Alomair, Basel; Alouini, Mohamed-Slim

    2014-01-01

    We consider a wiretap channel consisting of a source with multiple antennas, a legitimate receiver and an eavesdropper with a single antenna each. The channels between the source and the receivers undergo fast fading. We assume that the transmitter, in addition to the statistics of both channels, is only aware of a noisy version of the CSI to the legitimate receiver referred to as main channel. The legitimate receiver is aware of both its instantaneous channel gain and the transmitter's estimate of the main channel. On the other hand, the eavesdropper's receiver, in addition to its instantaneous channel realization, is aware of the actual main CSI and the transmitter's estimate as well. While the capacity of this channel is still open even with perfect CSI at the transmitter, we provide in this paper upper and lower bounds on the secrecy capacity. The upper bound is tighter than the one corresponding to perfect main CSI and the gap between the two upper bounds is characterized in function of the channel estimation error variance, at high-SNR. Furthermore, we show that our upper and lower bounds coincide in the case of no main CSI providing a trivial secrecy capacity.

  15. A Hot Knife Through Ice-Cream: Earthflow Response to Channel Incision (Or Channel Response to Earthflows?), Eel River Canyon, California

    Science.gov (United States)

    Mackey, B. H.; Roering, J. J.; McKean, J. A.

    2007-12-01

    Abundant glacier-like earthflow features are recognized as a primary erosional process in the highly erodable Franciscan Melange of the Eel River Basin, CA. Despite their prominence in this "melting ice-cream" topography, many questions regarding their effects on the long term sediment flux from this rapidly eroding basin remain unresolved. For example, does an earthflow's basal shear zone propagate vertically downwards with vertical river incision? What controls the upslope and lateral extent of individual earthflows? How does the erosive power of a river influence the rate of earthflow movement, or conversely do earthflow toe deposits regulate the rate of river incision? Here we present preliminary findings derived from study of 200km2 of lidar data (1m resolution) covering hillslopes adjacent to 30km of the Eel River. Lidar allows detailed analysis of the interaction between earthflows and the drainage network, and we document how inferred changes in local base level are propagated throughout adjacent hillslopes via earthflow movement. The most active earthflows (determined by field surveying and analysis of aerial photos rectified using lidar- generated digital topography) coincide with locally steep sections of channel, while downstream of the most active flows we frequently observe less-active or dormant earthflows. This observation supports the idea that the locations of the most active earthflows coincide with headward propagating knickpoints in the channel. The rate of earthflow movement appears to slow when an earthflow exhausts the upslope area of easily mobilized sediment. Earthflow toes can protrude directly into the channel, causing the channel to narrow and steepen, and even undercut the opposite bank. Large resistant boulders (>2m diameter) transported by the earthflow accumulate in the streambed and appear to both act as a check on further channel incision and earthflow movement. In contrast, areas adjacent to active earthflows exhibit smooth

  16. Information transmission and recovery in neural communications channels

    International Nuclear Information System (INIS)

    Eguia, M. C.; Rabinovich, M. I.; Abarbanel, H. D. I.

    2000-01-01

    behavior is strikingly different than the passive role communications channels usually play, and the ''data processing theorem'' of conventional communications theory is violated by these neural channels. Our calculations indicate that neurons can reinforce reliable transmission along a chain even when the synapses and the neurons are not completely reliable components. This phenomenon is generic in parameter space, robust in the presence of noise, and independent of the discretization process. Our results suggest a framework in which one might understand the apparent design complexity of neural information transduction networks. If networks with many dynamical neurons can recover information not apparent at various waystations in the communications channel, such networks may be more robust to noisy signals, may be more capable of communicating many types of encoded sensory neural information, and may be the appropriate design for components, neurons and synapses, which can be individually imprecise, inaccurate ''devices.''

  17. A linearization of quantum channels

    Science.gov (United States)

    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.

  18. Meiofauna communities from the Straits of Magellan and the Beagle Channel

    Directory of Open Access Journals (Sweden)

    G. C. Chen

    1999-12-01

    Full Text Available Meiofauna from 20 stations (ranging between 8 and 550 m in the Magellan Straits and the Beagle Channel revealed 28 small sized taxa of higher categories including the temporary meiofauna. Nematoda, Copepoda Harpacticoidea and Polychaeta occurred in all samples; Turbellaria, Bivalvia, Kinorhyncha and Ostracoda were regularly present. Nematodes represented between 68% and 94% of the meiofauna at each station, followed by the copepods (2.3% to 14.5% and polychaetes (1.1% to 11.5%. Maximal total density, 9700 individuals 10 cm-2, was found in the surroundings of Picton Island, while the mean abundance per station was 3374 individuals 10 cm-2. The vertical pattern within the sediment showed that 87% of meiofauna components concentrated in the upper 0-5 cm sediment layers and 13% in the lower ( > 5cm layers. More than 95% of copepods, as well as the temporary meiofauna occurred in the top 5 cm layers. The proportion of nematodes and copepods shows opposite trends in the vertical distribution. Multivariate analysis using the total density and the 10 `true´ meiofauna taxa densities discriminates between communities in the Straits of Magellan and the Beagle Channel area. Meiofaunal density was much higher in the Beagle Channel, but the diversity was lower than that in the Straits of Magellan. The Southern Magellan meiofauna communities are compared with those found at the Antarctic Peninsula and in the Weddell Sea (high Antarctic. It is considered that hydrodynamic features (tidal currents with strong winds, geographical characteristics, together with sediment composition are the key parameters structuring the meiofauna community in the Straits of Magellan and in the Beagle Channel.

  19. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Yang Haibing

    2007-01-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a -factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  20. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Haibing Yang

    2007-05-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a K-factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  1. Thrombosed false channel in acute aortic dissections

    International Nuclear Information System (INIS)

    Alerci, M.; Dore, R.; Kluzer, A.; Digiulio, G.; D'Andrea, F.; De Agostini, A.

    1987-01-01

    Three cases are reported of acute dissection with complete thrombosis of the false channel, which is a very uncommonevent in DeBakey's I and II type aortic dissections. The 3 patients entered hospital because of severe thoracic pain without any ECG sign of myocardial infarction. Emergency CT showed evidence of pericardial effusion suggesting hemopericardium, enlargement of the ascending aorta and a peripheral semilunar filling defect which caused a slight deformation of the true channel. On precontrast scans, only one case showed inward displacement of peripheral calcifications and high-density aortic wall. No tipical signs of aortic dissection were reported, expect in the first patient - where a double contrast filled lumen, separated by an intimal flap was seen. CT findings are individually discussed. It is emphasized that in all patients more than one CT sign was present at a time. The correct evaluation of these signs together with the clinacal data could lead to the right diagnosis of aortic dissection in spite of the lack of a f???

  2. Mechanisms of Gain Control by Voltage-Gated Channels in Intrinsically-Firing Neurons

    Science.gov (United States)

    Patel, Ameera X.; Burdakov, Denis

    2015-01-01

    Gain modulation is a key feature of neural information processing, but underlying mechanisms remain unclear. In single neurons, gain can be measured as the slope of the current-frequency (input-output) relationship over any given range of inputs. While much work has focused on the control of basal firing rates and spike rate adaptation, gain control has been relatively unstudied. Of the limited studies on gain control, some have examined the roles of synaptic noise and passive somatic currents, but the roles of voltage-gated channels present ubiquitously in neurons have been less explored. Here, we systematically examined the relationship between gain and voltage-gated ion channels in a conductance-based, tonically-active, model neuron. Changes in expression (conductance density) of voltage-gated channels increased (Ca2+ channel), reduced (K+ channels), or produced little effect (h-type channel) on gain. We found that the gain-controlling ability of channels increased exponentially with the steepness of their activation within the dynamic voltage window (voltage range associated with firing). For depolarization-activated channels, this produced a greater channel current per action potential at higher firing rates. This allowed these channels to modulate gain by contributing to firing preferentially at states of higher excitation. A finer analysis of the current-voltage relationship during tonic firing identified narrow voltage windows at which the gain-modulating channels exerted their effects. As a proof of concept, we show that h-type channels can be tuned to modulate gain by changing the steepness of their activation within the dynamic voltage window. These results show how the impact of an ion channel on gain can be predicted from the relationship between channel kinetics and the membrane potential during firing. This is potentially relevant to understanding input-output scaling in a wide class of neurons found throughout the brain and other nervous systems

  3. Localization and Molecular Determinants of the Hanatoxin Receptors on the Voltage-Sensing Domains of a K+ Channel

    Science.gov (United States)

    Li-Smerin, Yingying; Swartz, Kenton J.

    2000-01-01

    Hanatoxin inhibits voltage-gated K+ channels by modifying the energetics of activation. We studied the molecular determinants and physical location of the Hanatoxin receptors on the drk1 voltage-gated K+ channel. First, we made multiple substitutions at three previously identified positions in the COOH terminus of S3 to examine whether these residues interact intimately with the toxin. We also examined a region encompassing S1–S3 using alanine-scanning mutagenesis to identify additional determinants of the toxin receptors. Finally, guided by the structure of the KcsA K+ channel, we explored whether the toxin interacts with the peripheral extracellular surface of the pore domain in the drk1 K+ channel. Our results argue for an intimate interaction between the toxin and the COOH terminus of S3 and suggest that the Hanatoxin receptors are confined within the voltage-sensing domains of the channel, at least 20–25 Å away from the central pore axis. PMID:10828242

  4. Volume of the space of qubit-qubit channels and state transformations under random quantum channels

    OpenAIRE

    Lovas, Attila; Andai, Attila

    2017-01-01

    The simplest building blocks for quantum computations are the qubit-qubit quantum channels. In this paper, we analyze the structure of these channels via their Choi representation. The restriction of a quantum channel to the space of classical states (i.e. probability distributions) is called the underlying classical channel. The structure of quantum channels over a fixed classical channel is studied, the volume of general and unital qubit channels with respect to the Lebesgue measure is comp...

  5. The structure of a conserved piezo channel domain reveals a topologically distinct β sandwich fold.

    Science.gov (United States)

    Kamajaya, Aron; Kaiser, Jens T; Lee, Jonas; Reid, Michelle; Rees, Douglas C

    2014-10-07

    Piezo has recently been identified as a family of eukaryotic mechanosensitive channels composed of subunits containing over 2,000 amino acids, without recognizable sequence similarity to other channels. Here, we present the crystal structure of a large, conserved extramembrane domain located just before the last predicted transmembrane helix of C. elegans PIEZO, which adopts a topologically distinct β sandwich fold. The structure was also determined of a point mutation located on a conserved surface at the position equivalent to the human PIEZO1 mutation found in dehydrated hereditary stomatocytosis patients (M2225R). While the point mutation does not change the overall domain structure, it does alter the surface electrostatic potential that may perturb interactions with a yet-to-be-identified ligand or protein. The lack of structural similarity between this domain and any previously characterized fold, including those of eukaryotic and bacterial channels, highlights the distinctive nature of the Piezo family of eukaryotic mechanosensitive channels. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Correlation between Waardenburg syndrome phenotype and genotype in a population of individuals with identified PAX3 mutations.

    Science.gov (United States)

    DeStefano, A L; Cupples, L A; Arnos, K S; Asher, J H; Baldwin, C T; Blanton, S; Carey, M L; da Silva, E O; Friedman, T B; Greenberg, J; Lalwani, A K; Milunsky, A; Nance, W E; Pandya, A; Ramesar, R S; Read, A P; Tassabejhi, M; Wilcox, E R; Farrer, L A

    1998-05-01

    Waardenburg syndrome (WS) type 1 is an autosomal dominant disorder characterized by sensorineural hearing loss, pigmentary abnormalities of the eye, hair, and skin, and dystopia canthorum. The phenotype is variable and affected individuals may exhibit only one or a combination of several of the associated features. To assess the relationship between phenotype and gene defect, clinical and genotype data on 48 families (271 WS individuals) collected by members of the Waardenburg Consortium were pooled. Forty-two unique mutations in the PAX3 gene, previously identified in these families, were grouped in five mutation categories: amino acid (AA) substitution in the paired domain, AA substitution in the homeodomain, deletion of the Ser-Thr-Pro-rich region, deletion of the homeodomain and the Ser-Thr-Pro-rich region, and deletion of the entire gene. These mutation classes are based on the structure of the PAX3 gene and were chosen to group mutations predicted to have similar defects in the gene product. Association between mutation class and the presence of hearing loss, eye pigment abnormality, skin hypopigmentation, or white forelock was evaluated using generalized estimating equations, which allowed for incorporation of a correlation structure that accounts for potential similarity among members of the same family. Odds for the presence of eye pigment abnormality, white forelock, and skin hypopigmentation were 2, 8, and 5 times greater, respectively, for individuals with deletions of the homeodomain and the Pro-Ser-Thr-rich region compared to individuals with an AA substitution in the homeodomain. Odds ratios that differ significantly from 1.0 for these traits may indicate that the gene products resulting from different classes of mutations act differently in the expression of WS. Although a suggestive association was detected for hearing loss with an odds ratio of 2.6 for AA substitution in the paired domain compared with AA substitution in the homeodomain, this odds

  7. Beyond the Manual Channel

    DEFF Research Database (Denmark)

    , the main focus there is on spoken languages in their written and spoken forms. This series of workshops, however, offers a forum for researchers focussing on sign languages. For the fourth time, the workshop had sign language corpora as its main topic. This time, the focus was on any aspect beyond...... the manual channel. Not surprisingly, most papers deal with non-manuals on the face. Once again, the papers at this workshop clearly identify the potentials of even closer cooperation between sign linguists and sign language engineers, and we think it is events like this that contribute a lot to a better...

  8. Water removal characteristics of parallel serpentine channels. Paper no. IGEC-1-035

    International Nuclear Information System (INIS)

    Jiao, K.; Zhou, B.; Quan, P.

    2005-01-01

    Water management in a proton exchange membrane (PEM) fuel cell stack has been a challenging issue on the road to commercialization. This paper presents a numerical investigation of air-water flow in parallel serpentine channels on cathode side of a PEM fuel cell stack by use of the commercial Computational Fluid Dynamics (CFD) software package FLUENT. Different air-water flow behaviours inside the serpentine flow channels with inlet and outlet manifolds were discussed. The results showed that there were significant variations of water distribution and pressure drop in different cells at different times. The 'collecting-and-separating effect' due to the serpentine shape of the gas flow channels, the pressure drop change due to the water distribution inside the outlet manifold were observed. Several gas flow problems of this type of parallel serpentine channels were identified and useful suggestions were given through investigating the flow patterns inside the channels and manifolds. (author)

  9. Performance Analysis of Iterative Channel Estimation and Multiuser Detection in Multipath DS-CDMA Channels

    Science.gov (United States)

    Li, Husheng; Betz, Sharon M.; Poor, H. Vincent

    2007-05-01

    This paper examines the performance of decision feedback based iterative channel estimation and multiuser detection in channel coded aperiodic DS-CDMA systems operating over multipath fading channels. First, explicit expressions describing the performance of channel estimation and parallel interference cancellation based multiuser detection are developed. These results are then combined to characterize the evolution of the performance of a system that iterates among channel estimation, multiuser detection and channel decoding. Sufficient conditions for convergence of this system to a unique fixed point are developed.

  10. Multi-channel motor evoked potential monitoring during anterior cervical discectomy and fusion

    Directory of Open Access Journals (Sweden)

    Dong-Gun Kim

    Full Text Available Objectives: Anterior cervical discectomy and fusion (ACDF surgery is the most common surgical procedure for the cervical spine with low complication rate. Despite the potential prognostic benefit, intraoperative neurophysiological monitoring (IONM, a method for detecting impending neurological compromise, is not routinely used in ACDF surgery. The present study aimed to identify the potential benefits of monitoring multi-channel motor evoked potentials (MEPs during ACDF surgery. Methods: We retrospectively reviewed 200 consecutive patients who received IONM with multi-channel MEPs and somatosensory evoked potentials (SSEPs. On average, 9.2 muscles per patient were evaluated under MEP monitoring. Results: The rate of MEP change during surgery in the multi-level ACDF group was significantly higher than the single-level group. Two patients from the single-level ACDF group (1.7% and four patients from the multi-level ACDF group (4.9% experienced post-operative motor deficits. Multi-channel MEPs monitoring during single and multi-level ACDF surgery demonstrated higher sensitivity, specificity, positive predictive and negative predictive value than SSEP monitoring. Conclusions: Multi-channel MEP monitoring might be beneficial for the detection of segmental injury as well as long tract injury during single- and multi-level ACDF surgery. Significance: This is first large scale study to identify the usefulness of multi-channel MEPs in monitoring ACDF surgery. Keywords: Disc disease, Somatosensory evoked potentials, Intraoperative neurophysiological monitoring, Motor evoked potentials, Anterior cervical discectomy and fusion

  11. Structure and band gap determination of irradiation-induced amorphous nano-channels in LiNbO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sachan, R., E-mail: sachanr@ornl.gov; Pakarinen, O. H.; Chisholm, M. F. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Liu, P. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); School of Physics, State Key Laboratory of Crystal Materials and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan 250100 (China); Patel, M. K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Zhang, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Wang, X. L. [School of Physics, State Key Laboratory of Crystal Materials and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan 250100 (China); Weber, W. J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2015-04-07

    The irradiation of lithium niobate with swift heavy ions results in the creation of amorphous nano-sized channels along the incident ion path. These nano-channels are on the order of a hundred microns in length and could be useful for photonic applications. However, there are two major challenges in these nano-channels characterization: (i) it is difficult to investigate the structural characteristics of these nano-channels due to their very long length and (ii) the analytical electron microscopic analysis of individual ion track is complicated due to electron beam sensitive nature of lithium niobate. Here, we report the first high resolution microscopic characterization of these amorphous nano-channels, widely known as ion-tracks, by direct imaging them at different depths in the material, and subsequently correlating the key characteristics with electronic energy loss of ions. Energetic Kr ions ({sup 84}Kr{sup 22} with 1.98 GeV energy) are used to irradiate single crystal lithium niobate with a fluence of 2 × 10{sup 10} ions/cm{sup 2}, which results in the formation of individual ion tracks with a penetration depth of ∼180 μm. Along the ion path, electron energy loss of the ions, which is responsible for creating the ion tracks, increases with depth under these conditions in LiNbO{sub 3}, resulting in increases in track diameter of a factor of ∼2 with depth. This diameter increase with electronic energy loss is consistent with predictions of the inelastic thermal spike model. We also show a new method to measure the band gap in individual ion track by using electron energy-loss spectroscopy.

  12. A novel hypothesis for the binding mode of HERG channel blockers

    International Nuclear Information System (INIS)

    Choe, Han; Nah, Kwang Hoon; Lee, Soo Nam; Lee, Han Sam; Lee, Hui Sun; Jo, Su Hyun; Leem, Chae Hun; Jang, Yeon Jin

    2006-01-01

    We present a new docking model for HERG channel blockade. Our new model suggests three key interactions such that (1) a protonated nitrogen of the channel blocker forms a hydrogen bond with the carbonyl oxygen of HERG residue T623; (2) an aromatic moiety of the channel blocker makes a π-π interaction with the aromatic ring of HERG residue Y652; and (3) a hydrophobic group of the channel blocker forms a hydrophobic interaction with the benzene ring of HERG residue F656. The previous model assumes two interactions such that (1) a protonated nitrogen of the channel blocker forms a cation-π interaction with the aromatic ring of HERG residue Y652; and (2) a hydrophobic group of the channel blocker forms a hydrophobic interaction with the benzene ring of HERG residue F656. To test these models, we classified 69 known HERG channel blockers into eight binding types based on their plausible binding modes, and further categorized them into two groups based on the number of interactions our model would predict with the HERG channel (two or three). We then compared the pIC 5 value distributions between these two groups. If the old hypothesis is correct, the distributions should not differ between the two groups (i.e., both groups show only two binding interactions). If our novel hypothesis is correct, the distributions should differ between Groups 1 and 2. Consistent with our hypothesis, the two groups differed with regard to pIC 5 , and the group having more predicted interactions with the HERG channel had a higher mean pIC 5 value. Although additional work will be required to further validate our hypothesis, this improved understanding of the HERG channel blocker binding mode may help promote the development of in silico predictions methods for identifying potential HERG channel blockers

  13. The Arabidopsis guard cell outward potassium channel GORK is regulated by CPK33.

    Science.gov (United States)

    Corratgé-Faillie, Claire; Ronzier, Elsa; Sanchez, Frédéric; Prado, Karine; Kim, Jeong-Hyeon; Lanciano, Sophie; Leonhardt, Nathalie; Lacombe, Benoît; Xiong, Tou Cheu

    2017-07-01

    A complex signaling network involving voltage-gated potassium channels from the Shaker family contributes to the regulation of stomatal aperture. Several kinases and phosphatases have been shown to be crucial for ABA-dependent regulation of the ion transporters. To date, the Ca 2+ -dependent regulation of Shaker channels by Ca 2+ -dependent protein kinases (CPKs) is still elusive. A functional screen in Xenopus oocytes was launched to identify such CPKs able to regulate the three main guard cell Shaker channels KAT1, KAT2, and GORK. Seven guard cell CPKs were tested and multiple CPK/Shaker couples were identified. Further work on CPK33 indicates that GORK activity is enhanced by CPK33 and unaffected by a nonfunctional CPK33 (CPK33-K102M). Furthermore, Ca 2+ -induced stomatal closure is impaired in two cpk33 mutant plants. © 2017 Federation of European Biochemical Societies.

  14. On the secrecy capacity of the MISO wiretap channel under imperfect channel estimation

    KAUST Repository

    Rezki, Zouheir

    2014-12-01

    We consider a wiretap channel consisting of a source with multiple antennas, a legitimate receiver and an eavesdropper with a single antenna each. The channels between the source and the receivers undergo fast fading. We assume that the transmitter, in addition to the statistics of both channels, is only aware of a noisy version of the CSI to the legitimate receiver referred to as main channel. The legitimate receiver is aware of both its instantaneous channel gain and the transmitter\\'s estimate of the main channel. On the other hand, the eavesdropper\\'s receiver, in addition to its instantaneous channel realization, is aware of the actual main CSI and the transmitter\\'s estimate as well. While the capacity of this channel is still open even with perfect CSI at the transmitter, we provide in this paper upper and lower bounds on the secrecy capacity. The upper bound is tighter than the one corresponding to perfect main CSI and the gap between the two upper bounds is characterized in function of the channel estimation error variance, at high-SNR. Furthermore, we show that our upper and lower bounds coincide in the case of no main CSI providing a trivial secrecy capacity.

  15. Identification of an HV 1 voltage-gated proton channel in insects.

    Science.gov (United States)

    Chaves, Gustavo; Derst, Christian; Franzen, Arne; Mashimo, Yuta; Machida, Ryuichiro; Musset, Boris

    2016-04-01

    The voltage-gated proton channel 1 (HV 1) is an important component of the cellular proton extrusion machinery and is essential for charge compensation during the respiratory burst of phagocytes. HV 1 has been identified in a wide range of eukaryotes throughout the animal kingdom, with the exception of insects. Therefore, it has been proposed that insects do not possess an HV 1 channel. In the present study, we report the existence of an HV 1-type proton channel in insects. We searched insect transcriptome shotgun assembly (TSA) sequence databases and found putative HV 1 orthologues in various polyneopteran insects. To confirm that these putative HV 1 orthologues were functional channels, we studied the HV 1 channel of Nicoletia phytophila (NpHV 1), an insect of the Zygentoma order, in more detail. NpHV 1 comprises 239 amino acids and is 33% identical to the human voltage-gated proton channel 1. Patch clamp measurements in a heterologous expression system showed proton selectivity, as well as pH- and voltage-dependent gating. Interestingly, NpHV 1 shows slightly enhanced pH-dependent gating compared to the human channel. Mutations in the first transmembrane segment at position 66 (Asp66), the presumed selectivity filter, lead to a loss of proton-selective conduction, confirming the importance of this aspartate residue in voltage-gated proton channels. Nucleotide sequence data have been deposited in the GenBank database under accession number KT780722. © 2016 Federation of European Biochemical Societies.

  16. Channel electron multipliers

    International Nuclear Information System (INIS)

    Seidman, A.; Avrahami, Z.; Sheinfux, B.; Grinberg, J.

    1976-01-01

    A channel electron multiplier is described having a tubular wall coated with a secondary-electron emitting material and including an electric field for accelerating the electrons, the electric field comprising a plurality of low-resistive conductive rings each alternating with a high-resistive insulating ring. The thickness of the low-resistive rings is many times larger than that of the high-resistive rings, being in the order of tens of microns for the low-resistive rings and at least one order of magnitude lower for the high-resistive rings; and the diameter of the channel tubular walls is also many times larger than the thickness of the high-resistive rings. Both single-channel and multiple-channel electron multipliers are described. A very important advantage, particularly in making multiple-channel multipliers, is the simplicity of the procedure that may be used in constructing such multipliers. Other operational advantages are described

  17. A channel-by-channel method of reducing the errors associated with peak area integration

    International Nuclear Information System (INIS)

    Luedeke, T.P.; Tripard, G.E.

    1996-01-01

    A new method of reducing the errors associated with peak area integration has been developed. This method utilizes the signal content of each channel as an estimate of the overall peak area. These individual estimates can then be weighted according to the precision with which each estimate is known, producing an overall area estimate. Experimental measurements were performed on a small peak sitting on a large background, and the results compared to those obtained from a commercial software program. Results showed a marked decrease in the spread of results around the true value (obtained by counting for a long period of time), and a reduction in the statistical uncertainty associated with the peak area. (orig.)

  18. Micro-Spectroscopic Chemical Imaging of Individual Identified Marine Biogenic and Ambient Organic Ice Nuclei (Invited)

    Science.gov (United States)

    Knopf, D. A.; Alpert, P. A.; Wang, B.; OBrien, R. E.; Moffet, R. C.; Aller, J. Y.; Laskin, A.; Gilles, M.

    2013-12-01

    Atmospheric ice formation represents one of the least understood atmospheric processes with important implications for the hydrological cycle and climate. Current freezing descriptions assume that ice active sites on the particle surface initiate ice nucleation, however, the nature of these sites remains elusive. Here, we present a new experimental method that allows us to relate physical and chemical properties of individual particles with observed water uptake and ice nucleation ability using a combination of micro-spectroscopic and optical single particle analytical techniques. We apply this method to field-collected particles and particles generated via bursting of bubbles produced by glass frit aeration and plunging water impingement jets in a mesocosm containing artificial sea water and bacteria and/or phytoplankton. The most efficient ice nuclei (IN) within a particle population are identified and characterized. Single particle characterization is achieved by computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy. A vapor controlled cooling-stage coupled to an optical microscope is used to determine the onsets of water uptake, immersion freezing, and deposition ice nucleation of the individual particles as a function of temperature (T) as low as 200 K and relative humidity (RH) up to water saturation. In addition, we perform CCSEM/EDX to obtain on a single particle level the elemental composition of the entire particle population. Thus, we can determine if the IN are exceptional in nature or belong to a major particle type class with respect to composition and size. We find that ambient and sea spray particles are coated by organic material and can induce ice formation under tropospheric relevant conditions. Micro-spectroscopic single particle analysis of the investigated particle samples invokes a potential

  19. Slopes To Prevent Trapping of Bubbles in Microfluidic Channels

    Science.gov (United States)

    Greer, Harold E.; Lee, Michael C.; Smith, J. Anthony; Willis, Peter A.

    2010-01-01

    The idea of designing a microfluidic channel to slope upward along the direction of flow of the liquid in the channel has been conceived to help prevent trapping of gas bubbles in the channel. In the original application that gave rise to this idea, the microfluidic channels are parts of micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. It is necessary to prevent trapping of gas bubbles in these devices because uninterrupted liquid pathways are essential for sustaining the electrical conduction and flows that are essential for CE. The idea is also applicable to microfluidic devices that may be developed for similar terrestrial microCE biotechnological applications or other terrestrial applications in which trapping of bubbles in microfluidic channels cannot be tolerated. A typical microCE device in the original application includes, among other things, multiple layers of borosilicate float glass wafers. Microfluidic channels are formed in the wafers, typically by use of wet chemical etching. The figure presents a simplified cross section of part of such a device in which the CE channel is formed in the lowermost wafer (denoted the channel wafer) and, according to the present innovation, slopes upward into a via hole in another wafer (denoted the manifold wafer) lying immediately above the channel wafer. Another feature of the present innovation is that the via hole in the manifold wafer is made to taper to a wider opening at the top to further reduce the tendency to trap bubbles. At the time of reporting the information for this article, an effort to identify an optimum technique for forming the slope and the taper was in progress. Of the techniques considered thus far, the one considered to be most promising is precision milling by use of femtosecond laser pulses. Other similar techniques that may work equally well are precision milling using a focused ion beam, or a small diamond

  20. Analysis of systematic error deviation of water temperature measurement at the fuel channel outlet of the reactor Maria

    International Nuclear Information System (INIS)

    Bykowski, W.

    2000-01-01

    The reactor Maria has two primary cooling circuits; fuel channels cooling circuit and reactor pool cooling circuit. Fuel elements are placed inside the fuel channels which are parallely linked in parallel, between the collectors. In the course of reactor operation the following measurements are performed: continuous measurement of water temperature at the fuel channels inlet, continuous measurement of water temperature at the outlet of each fuel channel and continuous measurement of water flow rate through each fuel channel. Based on those thermal-hydraulic parameters the instantaneous thermal power generated in each fuel channel is determined and by use of that value the thermal balance and the degree of fuel burnup is assessed. The work contains an analysis concerning estimate of the systematic error of temperature measurement at outlet of each fuel channel and so the erroneous assessment of thermal power extracted in each fuel channel and the burnup degree for the individual fuel element. The results of measurements of separate factors of deviations for the fuel channels are enclosed. (author)

  1. Identifying Empirically Supported Treatments for Pica in Individuals with Intellectual Disabilities

    Science.gov (United States)

    Hagopian, Louis P.; Rooker, Griffin W.; Rolider, Natalie U.

    2011-01-01

    The purpose of the current study was to critically examine the existing literature on the treatment of pica displayed by individuals with intellectual disabilities. Criteria for empirically supported treatments as described by Divisions 12 and 16 of APA, and adapted for studies employing single-case designs were used to review this body of…

  2. Cytoplasmic Domain of MscS Interacts with Cell Division Protein FtsZ: A Possible Non-Channel Function of the Mechanosensitive Channel in Escherichia Coli.

    Directory of Open Access Journals (Sweden)

    Piotr Koprowski

    Full Text Available Bacterial mechano-sensitive (MS channels reside in the inner membrane and are considered to act as emergency valves whose role is to lower cell turgor when bacteria enter hypo-osmotic environments. However, there is emerging evidence that members of the Mechano-sensitive channel Small (MscS family play additional roles in bacterial and plant cell physiology. MscS has a large cytoplasmic C-terminal region that changes its shape upon activation and inactivation of the channel. Our pull-down and co-sedimentation assays show that this domain interacts with FtsZ, a bacterial tubulin-like protein. We identify point mutations in the MscS C-terminal domain that reduce binding to FtsZ and show that bacteria expressing these mutants are compromised in growth on sublethal concentrations of β-lactam antibiotics. Our results suggest that interaction between MscS and FtsZ could occur upon inactivation and/or opening of the channel and could be important for the bacterial cell response against sustained stress upon stationary phase and in the presence of β-lactam antibiotics.

  3. Cytoplasmic Domain of MscS Interacts with Cell Division Protein FtsZ: A Possible Non-Channel Function of the Mechanosensitive Channel in Escherichia Coli.

    Science.gov (United States)

    Koprowski, Piotr; Grajkowski, Wojciech; Balcerzak, Marcin; Filipiuk, Iwona; Fabczak, Hanna; Kubalski, Andrzej

    2015-01-01

    Bacterial mechano-sensitive (MS) channels reside in the inner membrane and are considered to act as emergency valves whose role is to lower cell turgor when bacteria enter hypo-osmotic environments. However, there is emerging evidence that members of the Mechano-sensitive channel Small (MscS) family play additional roles in bacterial and plant cell physiology. MscS has a large cytoplasmic C-terminal region that changes its shape upon activation and inactivation of the channel. Our pull-down and co-sedimentation assays show that this domain interacts with FtsZ, a bacterial tubulin-like protein. We identify point mutations in the MscS C-terminal domain that reduce binding to FtsZ and show that bacteria expressing these mutants are compromised in growth on sublethal concentrations of β-lactam antibiotics. Our results suggest that interaction between MscS and FtsZ could occur upon inactivation and/or opening of the channel and could be important for the bacterial cell response against sustained stress upon stationary phase and in the presence of β-lactam antibiotics.

  4. Insulin activates single amiloride-blockable Na channels in a distal nephron cell line (A6).

    Science.gov (United States)

    Marunaka, Y; Hagiwara, N; Tohda, H

    1992-09-01

    Using the patch-clamp technique, we studied the effect of insulin on an amiloride-blockable Na channel in the apical membrane of a distal nephron cell line (A6) cultured on permeable collagen films for 10-14 days. NPo (N, number of channels per patch membrane; Po, average value of open probability of individual channels in the patch) under baseline conditions was 0.88 +/- 0.12 (SE)(n = 17). After making cell-attached patches on the apical membrane which contained Na channels, insulin (1 mU/ml) was applied to the serosal bath. While maintaining the cell-attached patch, NPo significantly increased to 1.48 +/- 0.19 (n = 17; P less than 0.001) after 5-10 min of insulin application. The open probability of Na channels was 0.39 +/- 0.01 (n = 38) under baseline condition, and increased to 0.66 +/- 0.03 (n = 38, P less than 0.001) after addition of insulin. The baseline single-channel conductance was 4pS, and neither the single-channel conductance nor the current-voltage relationship was significantly changed by insulin. These results indicate that insulin increases Na absorption in the distal nephron by increasing the open probability of the amiloride-blockable Na channel.

  5. Analysing Gas-Liquid Flow in PEM Electrolyser Micro-Channels

    DEFF Research Database (Denmark)

    Lafmejani, Saeed Sadeghi; Olesen, Anders Christian; Kær, Søren Knudsen

    2016-01-01

    and are fairly expensive. One means of increasing the hydrogen yield to cost ratio of such systems, is to increase the operating current density. However, at high current densities, management of heat and mass transfer in the anode current collector and channel becomes crucial. This entails that further...... understanding of the gas-liquid flow in both the porous media and the channel is necessary for insuring proper oxygen, water and heat management of the electrolysis cell. In this work, the patterns of vertical upward gas-liquid flow in a 5×1×94 mm micro-channel are experimentally analysed. A sheet of titanium...... felt is used as a permeable wall for permeation of air through a column of water similar to the phenomenon encountered at the anode. The transparent setup is operated ex-situ and the gas-liquid flow regimes are identified using a camera....

  6. Long-range forces affecting equilibrium inertial focusing behavior in straight high aspect ratio microfluidic channels

    Energy Technology Data Exchange (ETDEWEB)

    Reece, Amy E.; Oakey, John, E-mail: joakey@uwyo.edu [Department of Chemical Engineering, University of Wyoming, Laramie, Wyoming 82071 (United States)

    2016-04-15

    The controlled and directed focusing of particles within flowing fluids is a problem of fundamental and technological significance. Microfluidic inertial focusing provides passive and precise lateral and longitudinal alignment of small particles without the need for external actuation or sheath fluid. The benefits of inertial focusing have quickly enabled the development of miniaturized flow cytometers, size-selective sorting devices, and other high-throughput particle screening tools. Straight channel inertial focusing device design requires knowledge of fluid properties and particle-channel size ratio. Equilibrium behavior of inertially focused particles has been extensively characterized and the constitutive phenomena described by scaling relationships for straight channels of square and rectangular cross section. In concentrated particle suspensions, however, long-range hydrodynamic repulsions give rise to complex particle ordering that, while interesting and potentially useful, can also dramatically diminish the technique’s effectiveness for high-throughput particle handling applications. We have empirically investigated particle focusing behavior within channels of increasing aspect ratio and have identified three scaling regimes that produce varying degrees of geometrical ordering between focused particles. To explore the limits of inertial particle focusing and identify the origins of these long-range interparticle forces, we have explored equilibrium focusing behavior as a function of channel geometry and particle concentration. Experimental results for highly concentrated particle solutions identify equilibrium thresholds for focusing that scale weakly with concentration and strongly with channel geometry. Balancing geometry mediated inertial forces with estimates for interparticle repulsive forces now provide a complete picture of pattern formation among concentrated inertially focused particles and enhance our understanding of the fundamental limits

  7. Measurement channel of neutron flow based on software

    International Nuclear Information System (INIS)

    Rivero G, T.; Benitez R, J. S.

    2008-01-01

    The measurement of the thermal power in nuclear reactors is based mainly on the measurement of the neutron flow. The presence of these in the reactor core is associated to neutrons released by the fission reaction of the uranium-235. Once moderate, these neutrons are precursors of new fissions. This process it is known like chain reaction. Thus, the power to which works a nuclear reactor, he is proportional to the number of produced fissions and as these depend on released neutrons, also the power is proportional to the number of present neutrons. The measurement of the thermal power in a reactor is realized with called instruments nuclear channels. To low power (level source), these channels measure the individual counts of detected neutrons, whereas to a medium and high power, they measure the electrical current or fluctuation of the same one that generate the fission neutrons in ionization chambers especially designed to detect neutrons. For the case of TRIGA reactors, the measurement channels of neutron flow use discreet digital electronic technology makes some decades already. Recently new technological tools have arisen that allow developing new versions of nuclear channels of simple form and compacts. The present work consists of the development of a nuclear channel for TRIGA reactors based on the use of the correlated signal of a fission chamber for ample interval. This new measurement channel uses a data acquisition card of high speed and the data processing by software that to the being installed in a computer is created a virtual instrument, with what spreads in real time, in graphic and understandable form for the operator, the power indication to which it operates the nuclear reactor. This system when being based on software, offers a major versatility to realize changes in the signal processing and power monitoring algorithms. The experimental tests of neutronic power measurement show a reliable performance through seven decades of power, with a

  8. Coherifying quantum channels

    Science.gov (United States)

    Korzekwa, Kamil; Czachórski, Stanisław; Puchała, Zbigniew; Życzkowski, Karol

    2018-04-01

    Is it always possible to explain random stochastic transitions between states of a finite-dimensional system as arising from the deterministic quantum evolution of the system? If not, then what is the minimal amount of randomness required by quantum theory to explain a given stochastic process? Here, we address this problem by studying possible coherifications of a quantum channel Φ, i.e., we look for channels {{{Φ }}}{ \\mathcal C } that induce the same classical transitions T, but are ‘more coherent’. To quantify the coherence of a channel Φ we measure the coherence of the corresponding Jamiołkowski state J Φ. We show that the classical transition matrix T can be coherified to reversible unitary dynamics if and only if T is unistochastic. Otherwise the Jamiołkowski state {J}{{Φ }}{ \\mathcal C } of the optimally coherified channel is mixed, and the dynamics must necessarily be irreversible. To assess the extent to which an optimal process {{{Φ }}}{ \\mathcal C } is indeterministic we find explicit bounds on the entropy and purity of {J}{{Φ }}{ \\mathcal C }, and relate the latter to the unitarity of {{{Φ }}}{ \\mathcal C }. We also find optimal coherifications for several classes of channels, including all one-qubit channels. Finally, we provide a non-optimal coherification procedure that works for an arbitrary channel Φ and reduces its rank (the minimal number of required Kraus operators) from {d}2 to d.

  9. A novel toxin from Haplopelma lividum selectively inhibits the NAV1.8 channel and possesses potent analgesic efficacy

    DEFF Research Database (Denmark)

    Meng, Ping; Huang, Honggang; Wang, Gan

    2017-01-01

    Spider venoms are a complex mixture of peptides with a large number of neurotoxins targeting ion channels. Although thousands of peptide toxins have been identified from venoms of numerous species of spiders, many unknown species urgently need to be investigated. In this study, a novel sodium...... channel inhibitor, μ-TRTX-Hl1a, was identified from the venom of Haplopelma lividum. It contained eight cysteines and formed a conserved cysteine pattern of ICK motif. μ-TRTX-Hl1a inhibited the TTX-resistant (TTX-r) sodium channel current rather than the TTX-sensitive (TTX-s) sodium channel current...

  10. 32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry.

    Science.gov (United States)

    Wiggins, G C; Triantafyllou, C; Potthast, A; Reykowski, A; Nittka, M; Wald, L L

    2006-07-01

    A 32-channel 3T receive-only phased-array head coil was developed for human brain imaging. The helmet-shaped array was designed to closely fit the head with individual overlapping circular elements arranged in patterns of hexagonal and pentagonal symmetry similar to that of a soccer ball. The signal-to-noise ratio (SNR) and noise amplification (g-factor) in accelerated imaging applications were quantitatively evaluated in phantom and human images and compared with commercially available head coils. The 32-channel coil showed SNR gains of up to 3.5-fold in the cortex and 1.4-fold in the corpus callosum compared to a (larger) commercial eight-channel head coil. The experimentally measured g-factor performance of the helmet array showed significant improvement compared to the eight-channel array (peak g-factor 59% and 26% of the eight-channel values for four- and fivefold acceleration). The performance of the arrays is demonstrated in high-resolution and highly accelerated brain images. Copyright (c) 2006 Wiley-Liss, Inc.

  11. C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1.

    Science.gov (United States)

    Mumm, Patrick; Imes, Dennis; Martinoia, Enrico; Al-Rasheid, Khaled A S; Geiger, Dietmar; Marten, Irene; Hedrich, Rainer

    2013-09-01

    Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al(3+)-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al(3+)-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activation–deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.

  12. Study of the structure of the particles of channel black of phase-contrasting electron microscopy of high resolution

    Energy Technology Data Exchange (ETDEWEB)

    Varlakov, V.P.; Fialkov, A.S.; Smirnov, B.N.

    1981-01-01

    The structure of channel black, DG-100, in the initial and graphitized states has been studied by phase-contrasting electron microscopy with a direct resolution of the carbon layers. An individual carbon layer is the main structural element of carbon black. The structure of channel black in the graphitized state looks like a hollow closed polyhedron made up of bundles of continuous carbon layers which can bend and become deformed to a great extent, testifying to the polymeric nature of the structure of channel black. The authors give an interpretation of the roentgen values of the 'dimensions of crystallites' in channel black.

  13. The Extended-Window Channel Estimator for Iterative Channel-and-Symbol Estimation

    Directory of Open Access Journals (Sweden)

    Barry John R

    2005-01-01

    Full Text Available The application of the expectation-maximization (EM algorithm to channel estimation results in a well-known iterative channel-and-symbol estimator (ICSE. The EM-ICSE iterates between a symbol estimator based on the forward-backward recursion (BCJR equalizer and a channel estimator, and may provide approximate maximum-likelihood blind or semiblind channel estimates. Nevertheless, the EM-ICSE has high complexity, and it is prone to misconvergence. In this paper, we propose the extended-window (EW estimator, a novel channel estimator for ICSE that can be used with any soft-output symbol estimator. Therefore, the symbol estimator may be chosen according to performance or complexity specifications. We show that the EW-ICSE, an ICSE that uses the EW estimator and the BCJR equalizer, is less complex and less susceptible to misconvergence than the EM-ICSE. Simulation results reveal that the EW-ICSE may converge faster than the EM-ICSE.

  14. CHANNEL ESTIMATION TECHNIQUE

    DEFF Research Database (Denmark)

    2015-01-01

    A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over the communicat......A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over...... the communication channel. The method further includes determining a sequence of second coefficient estimates of the communication channel based on a decomposition of the first coefficient estimates in a dictionary matrix and a sparse vector of the second coefficient estimates, the dictionary matrix including...... filter characteristics of at least one known transceiver filter arranged in the communication channel....

  15. Combining satellite photographs and raster lidar data for channel connectivity in tidal marshes.

    Science.gov (United States)

    Li, Zhi; Hodges, Ben

    2017-04-01

    High resolution airborne lidar is capable of providing topographic detail down to the 1 x 1 m scale or finer over large tidal marshes of a river delta. Such data sets can be challenging to develop and ground-truth due to the inherent complexities of the environment, the relatively small changes in elevation throughout a marsh, and practical difficulties in accessing the variety of flooded, dry, and muddy regions. Standard lidar point-cloud processing techniques (as typically applied in large lidar data collection program) have a tendency to mis-identify narrow channels and water connectivity in a marsh, which makes it difficult to directly use such data for modeling marsh flows. Unfortunately, it is not always practical, or even possible, to access the point cloud and re-analyze the raw lidar data when discrepancies have been found in a raster work product. Faced with this problem in preparing a model of the Trinity River delta (Texas, USA), we developed an approach to integrating analysis of a lidar-based raster with satellite images. Our primary goal was to identify the clear land/water boundaries needed to identify channelization in the available rasterized lidar data. The channel extraction method uses pixelized satellite photographs that are stretched/distorted with image-processing techniques to match identifiable control features in both lidar and photographic data sets. A kmeans clustering algorithm was applied cluster pixels based on their colors, which is effective in separating land and water in a satellite photograph. The clustered image was matched to the lidar data such that the combination shows the channel network. In effect, we are able to use the fact that the satellite photograph is higher resolution than the lidar data, and thus provides connectivity in the clustering at a finer scale. The principal limitation of the method is the where the satellite image and lidar suffer from similar problems For example, vegetation overhanging a narrow

  16. Research on Cost Information Sharing and Channel Choice in a Dual-Channel Supply Chain

    Directory of Open Access Journals (Sweden)

    Huihui Liu

    2016-01-01

    Full Text Available Many studies examine information sharing in an uncertain demand environment in a supply chain. However there is little literature on cost information sharing in a dual-channel structure consisting of a retail channel and a direct sales channel. Assuming that the retail sale cost and direct sale cost are random variables with a general distribution, the paper investigates the retailer’s choice on cost information sharing in a Bertrand competition model. Based on the equilibrium outcome of information sharing, the manufacturer’s channel choice is discussed in detail. Our paper provides several interesting conclusions. In both single- and dual-channel structures, the retailer has little motivation to share its private cost information which is verified to be valuable for the manufacturer. When the cost correlation between the two channels increases, our analyses show that the manufacturer’s profit improves. However, when channel choice is involved, the value of information could play a different role. The paper finds that a dual-channel structure can benefit the manufacturer only when the cost correlation is sufficiently low. In addition, if the cost correlation is weak, the cost fluctuation will bring out the advantage of a dual-channel structure and adding a new direct channel will help in risk pooling.

  17. Purification and subunit structure of a putative K sup + -channel protein identified by its binding properties for dendrotoxin I

    Energy Technology Data Exchange (ETDEWEB)

    Rehm, H.; Lazdunski, M. (Centre National de la Recherche Scientifique, Nice (France))

    1988-07-01

    The binding protein for the K{sup +}-channel toxin dendrotoxin I was purified from a detergent extract of rat brain membranes. The purification procedure utilized chromatography on DEAE-Trisacryl, affinity chromatography on a dendrotoxin-I-Aca 22 column, and wheat germ agglutinin-Affigel 10 with a final 3,800- to 4,600-fold enrichment and a recovery of 8-16%. The high affinity (K{sub d}, 40-100 pM) and specificity of the binding site are retained throughout the purification procedure. Analysis of the purified material on silver-stained NaDodSO{sub 4}/polyacrylamide gel revealed three bands of M{sub r} 76,000-80,000, 38,000 and 35,000. Interestingly, the binding site for {sup 125}I-labeled mast cell degranulating peptide, another putative K{sup +}-channel ligand from bee venom, which induces long-term potentiation in hippocampus, seems to reside on the same protein complex, as both binding sites copurify through the entire purification protocol.

  18. The voltage-sensing domain of a phosphatase gates the pore of a potassium channel.

    Science.gov (United States)

    Arrigoni, Cristina; Schroeder, Indra; Romani, Giulia; Van Etten, James L; Thiel, Gerhard; Moroni, Anna

    2013-03-01

    The modular architecture of voltage-gated K(+) (Kv) channels suggests that they resulted from the fusion of a voltage-sensing domain (VSD) to a pore module. Here, we show that the VSD of Ciona intestinalis phosphatase (Ci-VSP) fused to the viral channel Kcv creates Kv(Synth1), a functional voltage-gated, outwardly rectifying K(+) channel. Kv(Synth1) displays the summed features of its individual components: pore properties of Kcv (selectivity and filter gating) and voltage dependence of Ci-VSP (V(1/2) = +56 mV; z of ~1), including the depolarization-induced mode shift. The degree of outward rectification of the channel is critically dependent on the length of the linker more than on its amino acid composition. This highlights a mechanistic role of the linker in transmitting the movement of the sensor to the pore and shows that electromechanical coupling can occur without coevolution of the two domains.

  19. Application of ELJ to create and maintain side channels in a dynamic gravel bed river

    Science.gov (United States)

    Crabbe, E.; Crowe Curran, J.; Ockelford, A.

    2017-12-01

    Braided and anastomosing rivers create and maintain a large amount of side channel habitat. Unfortunately, many rivers that were once multi-channel rivers have been constrained to single thread channels as a consequence of land use changes that occurred in the 19th and 20th centuries or earlier. An increasingly common management goal today is the re-creation of self-maintaining side and tributary habitat through as natural means as possible. This work examines the geomorphic history of one such channel and the success of recent rehabilitation efforts. Our case study comes from the South Fork Nooksack River in the Cascades Range in Washington State. The Nooksack River is a gravel and sand bed channel with a snowmelt dominated hydrograph. Engineered log jams (ELJ) have been employed to direct flow into side and chute channels with the larger goals of increasing overall channel complexity and salmon spawning opportunities. ELJs have been constructed on the channel since the 2000s, and the ELJs in the study reaches range in age up to 10 years. The size and design of individual jams within the reach vary, enabling a comparison between jam types. ELJs are evaluated for their ability to maintain gravel bar locations and open tributary channels through the snowmelt season over the reach scale. Additional goals of trapping wood onto the jams and existing bars, stabilizing channel banks, and allowing for the growth of bar vegetation are also examined.

  20. Calcium Occupancy of N-terminal Sites within Calmodulin Induces Inhibition of the Ryanodine Receptor Calcium Release Channel

    Energy Technology Data Exchange (ETDEWEB)

    Boschek, Curt B; Jones, Terry E; Squier, Thomas C; Bigelow, Diana J

    2007-08-01

    Calmodulin (CaM) regulates calcium release from intracellular stores in skeletal muscle through its association with the ryanodine receptor (RyR1) calcium release channel, where CaM association enhances channel opening at resting calcium levels and its closing at micromolar calcium levels associated with muscle contraction. A high-affinity CaM-binding sequence (RyRp) has been identified in RyR1, which corresponds to a 30-residue sequence (i.e., K3614 – N3643) located within the central portion of the primary sequence. However, it is currently unclear whether the identified CaM-binding sequence a) senses calcium over the physiological range of calcium-concentrations associated with RyR1 regulation or b) plays a structural role unrelated to the calcium-dependent modulation of RyR1 function. Therefore, we have measured the calcium-dependent activation of the individual domains of CaM in association with RyRp and their relationship to the CaM-dependent regulation of RyR1. These measurements utilize an engineered CaM, permitting the site-specific incorporation of N-(1-pyrene) maleimide at either T34C (PyN-CaM) or T110C (PyC-CaM) in the N- and C-domains, respectively. Consistent with prior measurements, we observe a high-affinity association between both apo- and calcium-activated CaM and RyRp. Upon association with RyRp, fluorescence changes in PyN-CaM or PyC-CaM permit the measurement of the calcium-activation of these individual domains. Fluorescence changes upon calcium-activation of PyC-CaM in association with RyRp are indicative of high-affinity calcium-dependent activation of the C-terminal domain of CaM bound to RyRp at resting calcium levels and the activation of the N-terminal domain at levels of calcium associated cellular activation. In comparison, occupancy of calcium-binding sites in the N-domain of CaM mirrors the calcium-dependence of RyR1 inhibition observed at activating calcium levels, where [Ca]1/2 = 4.3 0.4 μM, suggesting a direct regulation of Ry

  1. Assessing the Returns from Organic Marketing Channels

    OpenAIRE

    Park, Timothy A.

    2009-01-01

    Organic farmers face heightened pressure in developing a portfolio of different marketing channels and in bargaining competitively with increasingly sophisticated marketing participants in the supply chain for organic products. This research assists producers by identifying specific farm and demographic factors that enhance earnings given the choice of marketing outlet. The two significant selectivity coefficients confirm that organic earnings when marketing through a single outlet are biased...

  2. Meta-analysis of 375,000 individuals identifies 38 susceptibility loci for migraine.

    Science.gov (United States)

    Gormley, Padhraig; Anttila, Verneri; Winsvold, Bendik S; Palta, Priit; Esko, Tonu; Pers, Tune H; Farh, Kai-How; Cuenca-Leon, Ester; Muona, Mikko; Furlotte, Nicholas A; Kurth, Tobias; Ingason, Andres; McMahon, George; Ligthart, Lannie; Terwindt, Gisela M; Kallela, Mikko; Freilinger, Tobias M; Ran, Caroline; Gordon, Scott G; Stam, Anine H; Steinberg, Stacy; Borck, Guntram; Koiranen, Markku; Quaye, Lydia; Adams, Hieab H H; Lehtimäki, Terho; Sarin, Antti-Pekka; Wedenoja, Juho; Hinds, David A; Buring, Julie E; Schürks, Markus; Ridker, Paul M; Hrafnsdottir, Maria Gudlaug; Stefansson, Hreinn; Ring, Susan M; Hottenga, Jouke-Jan; Penninx, Brenda W J H; Färkkilä, Markus; Artto, Ville; Kaunisto, Mari; Vepsäläinen, Salli; Malik, Rainer; Heath, Andrew C; Madden, Pamela A F; Martin, Nicholas G; Montgomery, Grant W; Kurki, Mitja I; Kals, Mart; Mägi, Reedik; Pärn, Kalle; Hämäläinen, Eija; Huang, Hailiang; Byrnes, Andrea E; Franke, Lude; Huang, Jie; Stergiakouli, Evie; Lee, Phil H; Sandor, Cynthia; Webber, Caleb; Cader, Zameel; Muller-Myhsok, Bertram; Schreiber, Stefan; Meitinger, Thomas; Eriksson, Johan G; Salomaa, Veikko; Heikkilä, Kauko; Loehrer, Elizabeth; Uitterlinden, Andre G; Hofman, Albert; van Duijn, Cornelia M; Cherkas, Lynn; Pedersen, Linda M; Stubhaug, Audun; Nielsen, Christopher S; Männikkö, Minna; Mihailov, Evelin; Milani, Lili; Göbel, Hartmut; Esserlind, Ann-Louise; Christensen, Anne Francke; Hansen, Thomas Folkmann; Werge, Thomas; Kaprio, Jaakko; Aromaa, Arpo J; Raitakari, Olli; Ikram, M Arfan; Spector, Tim; Järvelin, Marjo-Riitta; Metspalu, Andres; Kubisch, Christian; Strachan, David P; Ferrari, Michel D; Belin, Andrea C; Dichgans, Martin; Wessman, Maija; van den Maagdenberg, Arn M J M; Zwart, John-Anker; Boomsma, Dorret I; Smith, George Davey; Stefansson, Kari; Eriksson, Nicholas; Daly, Mark J; Neale, Benjamin M; Olesen, Jes; Chasman, Daniel I; Nyholt, Dale R; Palotie, Aarno

    2016-08-01

    Migraine is a debilitating neurological disorder affecting around one in seven people worldwide, but its molecular mechanisms remain poorly understood. There is some debate about whether migraine is a disease of vascular dysfunction or a result of neuronal dysfunction with secondary vascular changes. Genome-wide association (GWA) studies have thus far identified 13 independent loci associated with migraine. To identify new susceptibility loci, we carried out a genetic study of migraine on 59,674 affected subjects and 316,078 controls from 22 GWA studies. We identified 44 independent single-nucleotide polymorphisms (SNPs) significantly associated with migraine risk (P < 5 × 10(-8)) that mapped to 38 distinct genomic loci, including 28 loci not previously reported and a locus that to our knowledge is the first to be identified on chromosome X. In subsequent computational analyses, the identified loci showed enrichment for genes expressed in vascular and smooth muscle tissues, consistent with a predominant theory of migraine that highlights vascular etiologies.

  3. Dynamics of premixed hydrogen/air flames in mesoscale channels

    Energy Technology Data Exchange (ETDEWEB)

    Pizza, Gianmarco [Paul Scherrer Institute, Combustion Research, CH-5232, Villigen PSI (Switzerland); Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, CH-8092, Zurich (Switzerland); Frouzakis, Christos E.; Boulouchos, Konstantinos [Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, CH-8092, Zurich (Switzerland); Mantzaras, John [Paul Scherrer Institute, Combustion Research, CH-5232, Villigen PSI (Switzerland); Tomboulides, Ananias G. [Department of Engineering and Management of Energy Resources, University of Western Macedonia, 50100 Kozani (Greece)

    2008-10-15

    Direct numerical simulation with detailed chemistry and transport is used to study the stabilization and dynamics of lean ({phi}=0.5) premixed hydrogen/air atmospheric pressure flames in mesoscale planar channels. Channel heights of h=2, 4, and 7 mm, and inflow velocities in the range 0.3{<=}U{sub IN}{<=}1100cm/ s are investigated. Six different burning modes are identified: mild combustion, ignition/extinction, closed steady symmetric flames, open steady symmetric flames, oscillating and, finally, asymmetric flames. Chaotic behavior of cellular flame structures is observed for certain values of U{sub IN}. Stability maps delineating the regions of the different flame types are finally constructed. (author)

  4. Voltage-Gated Calcium Channels

    Science.gov (United States)

    Zamponi, Gerald Werner

    Voltage Gated Calcium Channels is the first comprehensive book in the calcium channel field, encompassing over thirty years of progress towards our understanding of calcium channel structure, function, regulation, physiology, pharmacology, and genetics. This book balances contributions from many of the leading authorities in the calcium channel field with fresh perspectives from risings stars in the area, taking into account the most recent literature and concepts. This is the only all-encompassing calcium channel book currently available, and is an essential resource for academic researchers at all levels in the areas neuroscience, biophysics, and cardiovascular sciences, as well as to researchers in the drug discovery area.

  5. Multi-Channel RF System for MRI-Guided Transurethral Ultrasound Thermal Therapy

    Science.gov (United States)

    Yak, Nicolas; Asselin, Matthew; Chopra, Rajiv; Bronskill, Michael

    2009-04-01

    MRI-guided transurethral ultrasound thermal therapy is an approach to treating localized prostate cancer which targets precise deposition of thermal energy within a confined region of the gland. This treatment requires a system incorporating a heating applicator with multiple planar ultrasound transducers and associated RF electronics to control individual elements independently in order to achieve accurate 3D treatment. We report the design, construction, and characterization of a prototype multi-channel system capable of controlling 16 independent RF signals for a 16-element heating applicator. The main components are a control computer, microcontroller, and a 16-channel signal generator with 16 amplifiers, each incorporating a low-pass filter and transmitted/reflected power detection circuit. Each channel can deliver from 0.5 to 10 W of electrical power and good linearity from 3 to 12 MHz. Harmonic RF signals near the Larmor frequency of a 1.5 T MRI were measured to be below -30 dBm and heating experiments within the 1.5 T MR system showed no significant decrease in SNR of the temperature images. The frequency and power for all 16 channels could be changed in less than 250 ms, which was sufficiently rapid for proper performance of the control algorithms. A common backplane design was chosen which enabled an inexpensive, modular approach for each channel resulting in an overall system with minimal footprint.

  6. Incision of the Jezero Crater Outflow Channel by Fluvial Sediment Transport

    Science.gov (United States)

    Holo, S.; Kite, E. S.

    2017-12-01

    Jezero crater, the top candidate landing site for the Mars 2020 rover, once possessed a lake that over-spilled and eroded a large outflow channel into the Eastern rim. The Western deltaic sediments that would be the primary science target of the rover record a history of lake level, which is modulated by the inflow and outflow channels. While formative discharges for the Western delta exist ( 500 m3/s), little work has been done to see if these flows are the same responsible for outflow channel incision. Other models of the Jezero outflow channel incision assume that a single rapid flood (incision timescales of weeks), with unknown initial hydraulic head and no discharge into the lake (e.g. from the inflow channels or the subsurface), incised an open channel with discharge modulated by flow over a weir. We present an alternate model where, due to an instability at the threshold of sediment motion, the incision of the outflow channel occurs in concert with lake filling. In particular, we assume a simplified lake-channel-valley system geometry and that the channel is hydraulically connected to the filling/draining crater lake. Bed load sediment transport and water discharge through the channel are quantified using the Meyer-Peter and Mueller relation and Manning's law respectively. Mass is conserved for both water and sediment as the lake level rises/falls and the channel incises. This model does not resolve backwater effects or concavity in the alluvial system, but it does capture the non-linear feedbacks between lake draining, erosion rate, channel flow rate, and slope relaxation. We identify controls on incision of the outflow channel and estimate the time scale of outflow channel formation through a simple dynamical model. We find that the observed 300m of channel erosion can be reproduced in decades to centuries of progressive bed load as the delta forming flows fill the lake. This corresponds to time scales on the order of or smaller than the time scale

  7. Trafficking and intracellular regulation of Kv7.1 potassium channels in the heart

    DEFF Research Database (Denmark)

    Nielsen, Nathalie Hélix

    identified. About 100 of these mutations are located in the N- or the C-terminal parts of the channel. The aim of the present work was to gain a better understanding of the Kv7.1 channel protein function. In the first study we identified a Kv7.1 missense mutation in a German family with Long QT Syndrome......The electrical activity of the heart, measured by application of surface body electrodes and recorded as an electrocardiogram, is the result of a finely tuned balance of ion movement (K+, Na+, Ca2+). The ionic currents collectively constitute the cardiac action potential created in the cell...

  8. Resonance properties of tidal channels with multiple retention basins: role of adjacent sea

    Science.gov (United States)

    Roos, Pieter C.; Schuttelaars, Henk M.

    2015-03-01

    We present an idealised model of the tidal response in a main channel with multiple secondary basins, co-oscillating with an adjacent sea. The sea is represented as a semi-infinite strip of finite width, anywhere between the limits of a channel extension (narrow) and a half-plane (wide). The sea geometry controls the extent to which radiative damping takes place and hence the type of conditions that effectively apply at the channel mouth. These conditions range between the two extremes of prescribing elevation (deep sea limit) and prescribing the incoming wave (sea as channel extension of the same depth, as done in an earlier study). The closer to this first extreme, the stronger the oscillations in the secondary basins may feed back onto the channel mouth and thus produce an amplified or weakened response in the system as a whole. The possibly resonant response is explained by analysing the additional waves that emerge on either side of the entrance of the secondary basin. Finally, we show that the simultaneous presence of two secondary basins may amplify or weaken the accumulated responses to these basins individually.

  9. Porous Materials to Support Bilayer Lipid Membranes for Ion Channel Biosensors

    Directory of Open Access Journals (Sweden)

    Thai Phung

    2011-01-01

    Full Text Available To identify materials suitable as membrane supports for ion channel biosensors, six filter materials of varying hydrophobicity, tortuosity, and thickness were examined for their ability to support bilayer lipid membranes as determined by electrical impedance spectroscopy. Bilayers supported by hydrophobic materials (PTFE, polycarbonate, nylon, and silanised silver had optimal resistance (14–19 GΩ and capacitance (0.8–1.6 μF values whereas those with low hydrophobicity did not form BLMs (PVDF or were short-lived (unsilanised silver. The ability of ion channels to function in BLMs was assessed using a method recently reported to improve the efficiency of proteoliposome incorporation into PTFE-supported bilayers. Voltage-gated sodium channel activation by veratridine and inhibition by saxitoxin showed activity for PTFE, nylon, and silanised silver, but not polycarbonate. Bilayers on thicker, more tortuous, and hydrophobic materials produced higher current levels. Bilayers that self-assembled on PTFE filters were the longest lived and produced the most channel activity using this method.

  10. Evaluation of coherence interference in optical wireless communication through multiscattering channels.

    Science.gov (United States)

    Kedar, Debbie; Arnon, Shlomi

    2006-05-10

    Optical wireless communication has been the subject of much research in recent years because of the increasing interest in laser satellite-ground links and urban optical wireless communication. The major sources of performance degradation have been identified as the spatial, angular, and temporal spread of the propagating beam when the propagation channel is multiscattering, resulting in reduced power reception and intersignal interference, as well as turbulence-induced scintillations and noise due to receiver circuitry and background illumination. However, coherence effects due to multipath interference caused by a scattering propagation channel do not appear to have been treated in detail in the scientific literature. We attempt a theoretical analysis of coherence interference in optical wireless communication through scattering channels and try to quantify the resultant performance degradation for different media. We conclude that coherence interference is discernible in optical wireless communication through scattering channels and is highly dependent on the microscopic nature of the propagation medium.

  11. TRPV6 channels.

    Science.gov (United States)

    Fecher-Trost, Claudia; Weissgerber, Petra; Wissenbach, Ulrich

    2014-01-01

    TRPV6 (former synonyms ECAC2, CaT1, CaT-like) displays several specific features which makes it unique among the members of the mammalian Trp gene family (1) TRPV6 (and its closest relative, TRPV5) are the only highly Ca(2+)-selective channels of the entire TRP superfamily (Peng et al. 1999; Wissenbach et al. 2001; Voets et al. 2004). (2) Translation of Trpv6 initiates at a non-AUG codon, at ACG, located upstream of the annotated AUG, which is not used for initiation (Fecher-Trost et al. 2013). The ACG codon is nevertheless decoded by methionine. Not only a very rare event in eukaryotic biology, the full-length TRPV6 protein existing in vivo comprises an amino terminus extended by 40 amino acid residues compared to the annotated truncated TRPV6 protein which has been used in most studies on TRPV6 channel activity so far. (In the following numbering occurs according to this full-length protein, with the numbers of the so far annotated truncated protein in brackets). (3) Only in humans a coupled polymorphism of Trpv6 exists causing three amino acid exchanges and resulting in an ancestral Trpv6 haplotype and a so-called derived Trpv6 haplotype (Wissenbach et al. 2001). The ancestral allele encodes the amino acid residues C197(157), M418(378) and M721(681) and the derived alleles R197(157), V418(378) and T721(681). The ancestral haplotype is found in all species, the derived Trpv6 haplotype has only been identified in humans, and its frequency increases with the distance to the African continent. Apparently the Trpv6 gene has been a strong target for selection in humans, and its derived variant is one of the few examples showing consistently differences to the orthologues genes of other primates (Akey et al. 2004, 2006; Stajich and Hahn 2005; Hughes et al. 2008). (4) The Trpv6 gene expression is significantly upregulated in several human malignancies including the most common cancers, prostate and breast cancer (Wissenbach et al. 2001; Zhuang et al. 2002; Fixemer et al

  12. Large conductance Ca2+-activated K+ (BK channel: Activation by Ca2+ and voltage

    Directory of Open Access Journals (Sweden)

    RAMÓN LATORRE

    2006-01-01

    Full Text Available Large conductance Ca2+-activated K+ (BK channels belong to the S4 superfamily of K+ channels that include voltage-dependent K+ (Kv channels characterized by having six (S1-S6 transmembrane domains and a positively charged S4 domain. As Kv channels, BK channels contain a S4 domain, but they have an extra (S0 transmembrane domain that leads to an external NH2-terminus. The BK channel is activated by internal Ca2+, and using chimeric channels and mutagenesis, three distinct Ca2+-dependent regulatory mechanisms with different divalent cation selectivity have been identified in its large COOH-terminus. Two of these putative Ca2+-binding domains activate the BK channel when cytoplasmic Ca2+ reaches micromolar concentrations, and a low Ca2+ affinity mechanism may be involved in the physiological regulation by Mg2+. The presence in the BK channel of multiple Ca2+-binding sites explains the huge Ca2+ concentration range (0.1 μM-100 μM in which the divalent cation influences channel gating. BK channels are also voltage-dependent, and all the experimental evidence points toward the S4 domain as the domain in charge of sensing the voltage. Calcium can open BK channels when all the voltage sensors are in their resting configuration, and voltage is able to activate channels in the complete absence of Ca2+. Therefore, Ca2+ and voltage act independently to enhance channel opening, and this behavior can be explained using a two-tiered allosteric gating mechanism.

  13. Progress in Development of Improved Ion-Channel Biosensors

    Science.gov (United States)

    Nadeau, Jay L.; White, Victor E.; Maurer, Joshua A.; Dougherty, Dennis A.

    2008-01-01

    Further improvements have recently been made in the development of the devices described in Improved Ion-Channel Biosensors (NPO-30710), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 30. As discussed in more detail in that article, these sensors offer advantages of greater stability, greater lifetime, and individual electrical addressability, relative to prior ion-channel biosensors. In order to give meaning to a brief description of the recent improvements, it is necessary to recapitulate a substantial portion of the text of the cited previous article. The figure depicts one sensor that incorporates the recent improvements, and can be helpful in understanding the recapitulated text, which follows: These sensors are microfabricated from silicon and other materials compatible with silicon. Typically, the sensors are fabricated in arrays in silicon wafers on glass plates. Each sensor in the array can be individually electrically addressed, without interference with its neighbors. Each sensor includes a well covered by a thin layer of silicon nitride, in which is made a pinhole for the formation of a lipid bilayer membrane. In one stage of fabrication, the lower half of the well is filled with agarose, which is allowed to harden. Then the upper half of the well is filled with a liquid electrolyte (which thereafter remains liquid) and a lipid bilayer is painted over the pinhole. The liquid contains a protein that forms an ion channel on top of the hardened agarose. The combination of enclosure in the well and support by the hardened agarose provides the stability needed to keep the membrane functional for times as long as days or even weeks. An electrode above the well, another electrode below the well, and all the materials between the electrodes together constitute a capacitor. What is measured is the capacitive transient current in response to an applied voltage pulse. One notable feature of this sensor, in comparison with prior such sensors, is a

  14. Transmembrane helical interactions in the CFTR channel pore.

    Directory of Open Access Journals (Sweden)

    Jhuma Das

    2017-06-01

    Full Text Available Mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR gene affect CFTR protein biogenesis or its function as a chloride channel, resulting in dysregulation of epithelial fluid transport in the lung, pancreas and other organs in cystic fibrosis (CF. Development of pharmaceutical strategies to treat CF requires understanding of the mechanisms underlying channel function. However, incomplete 3D structural information on the unique ABC ion channel, CFTR, hinders elucidation of its functional mechanism and correction of cystic fibrosis causing mutants. Several CFTR homology models have been developed using bacterial ABC transporters as templates but these have low sequence similarity to CFTR and are not ion channels. Here, we refine an earlier model in an outward (OWF and develop an inward (IWF facing model employing an integrated experimental-molecular dynamics simulation (200 ns approach. Our IWF structure agrees well with a recently solved cryo-EM structure of a CFTR IWF state. We utilize cysteine cross-linking to verify positions and orientations of residues within trans-membrane helices (TMHs of the OWF conformation and to reconstruct a physiologically relevant pore structure. Comparison of pore profiles of the two conformations reveal a radius sufficient to permit passage of hydrated Cl- ions in the OWF but not the IWF model. To identify structural determinants that distinguish the two conformations and possible rearrangements of TMHs within them responsible for channel gating, we perform cross-linking by bifunctional reagents of multiple predicted pairs of cysteines in TMH 6 and 12 and 6 and 9. To determine whether the effects of cross-linking on gating observed are the result of switching of the channel from open to close state, we also treat the same residue pairs with monofunctional reagents in separate experiments. Both types of reagents prevent ion currents indicating that pore blockage is primarily responsible.

  15. Long-pore Electrostatics in Inward-rectifier Potassium Channels

    Science.gov (United States)

    Robertson, Janice L.; Palmer, Lawrence G.; Roux, Benoît

    2008-01-01

    Inward-rectifier potassium (Kir) channels differ from the canonical K+ channel structure in that they possess a long extended pore (∼85 Å) for ion conduction that reaches deeply into the cytoplasm. This unique structural feature is presumably involved in regulating functional properties specific to Kir channels, such as conductance, rectification block, and ligand-dependent gating. To elucidate the underpinnings of these functional roles, we examine the electrostatics of an ion along this extended pore. Homology models are constructed based on the open-state model of KirBac1.1 for four mammalian Kir channels: Kir1.1/ROMK, Kir2.1/IRK, Kir3.1/GIRK, and Kir6.2/KATP. By solving the Poisson-Boltzmann equation, the electrostatic free energy of a K+ ion is determined along each pore, revealing that mammalian Kir channels provide a favorable environment for cations and suggesting the existence of high-density regions in the cytoplasmic domain and cavity. The contribution from the reaction field (the self-energy arising from the dielectric polarization induced by the ion's charge in the complex geometry of the pore) is unfavorable inside the long pore. However, this is well compensated by the electrostatic interaction with the static field arising from the protein charges and shielded by the dielectric surrounding. Decomposition of the static field provides a list of residues that display remarkable correspondence with existing mutagenesis data identifying amino acids that affect conduction and rectification. Many of these residues demonstrate interactions with the ion over long distances, up to 40 Å, suggesting that mutations potentially affect ion or blocker energetics over the entire pore. These results provide a foundation for understanding ion interactions in Kir channels and extend to the study of ion permeation, block, and gating in long, cation-specific pores. PMID:19001143

  16. Evaluation channel performance in multichannel environments

    NARCIS (Netherlands)

    Gensler, S.; Dekimpe, M.; Skiera, B.

    2007-01-01

    Evaluating channel performance is crucial for actively managing multiple sales channels, and requires understanding the customers' channel preferences. Two key components of channel performance are (i) the existing customers' intrinsic loyalty to a particular channel and (ii) the channel's ability

  17. Maja Valles, Mars: A Multi-Source Fluvio-Volcanic Outflow Channel System

    Science.gov (United States)

    Keske, A.; Christensen, P. R.

    2017-12-01

    The resemblance of martian outflow channels to the channeled scablands of the Pacific Northwest has led to general consensus that they were eroded by large-scale flooding. However, the observation that many of these channels are coated in lava issuing from the same source as the water source has motivated the alternative hypothesis that the channels were carved by fluid, turbulent lava. Maja Valles is a circum-Chryse outflow channel whose origin was placed in the late Hesperian by Baker and Kochel (1979), with more recent studies of crater density variations suggesting that its formation history involved multiple resurfacing events (Chapman et al., 2003). In this study, we have found that while Maja Valles indeed host a suite of standard fluvial landforms, its northern portion is thinly coated with lava that has buried much of the older channel landforms and overprinted them with effusive flow features, such as polygons and bathtub rings. Adjacent to crater pedestals and streamlined islands are patches of dark, relatively pristine material pooled in local topographic lows that we have interpreted as ponds of lava remaining from one or more fluid lava flows that flooded the channel system and subsequently drained, leaving marks of the local lava high stand. Despite the presence of fluvial landforms throughout the valles, lava flow features exist in the northern reaches of the system alone, 500-1200 km from the channels' source. The flows can instead be traced to a collection of vents in Lunae Plaum, west of the valles. In previously studied fluvio-volcanic outflow systems, such as Athabasca Valles, the sources of the volcanic activity and fluvial activity have been indistinguishable. In contrast, Maja Valles features numerous fluvio-volcanic landforms bearing similarity to those identified in other channel systems, yet the source of its lava flows is distinct from the source of its channels. Furthermore, in the absence of any channels between the source of the lava

  18. The Art of Athlete Leadership: Identifying High-Quality Athlete Leadership at the Individual and Team Level Through Social Network Analysis.

    Science.gov (United States)

    Fransen, Katrien; Van Puyenbroeck, Stef; Loughead, Todd M; Vanbeselaere, Norbert; De Cuyper, Bert; Vande Broek, Gert; Boen, Filip

    2015-06-01

    This research aimed to introduce social network analysis as a novel technique in sports teams to identify the attributes of high-quality athlete leadership, both at the individual and at the team level. Study 1 included 25 sports teams (N = 308 athletes) and focused on athletes' general leadership quality. Study 2 comprised 21 sports teams (N = 267 athletes) and focused on athletes' specific leadership quality as a task, motivational, social, and external leader. The extent to which athletes felt connected with their leader proved to be most predictive for athletes' perceptions of that leader's quality on each leadership role. Also at the team level, teams with higher athlete leadership quality were more strongly connected. We conclude that social network analysis constitutes a valuable tool to provide more insight in the attributes of high-quality leadership both at the individual and at the team level.

  19. Optimal complex exponentials BEM and channel estimation in doubly selective channel

    International Nuclear Information System (INIS)

    Song, Lijun; Lei, Xia; Yu, Feng; Jin, Maozhu

    2016-01-01

    Over doubly selective channel, the optimal complex exponentials BEM (CE-BEM) is required to characterize the transmission in transform domain in order to reducing the huge number of the estimated parameters during directly estimating the impulse response in time domain. This paper proposed an improved CE-BEM to alleviating the high frequency sampling error caused by conventional CE-BEM. On the one hand, exploiting the improved CE-BEM, we achieve the sampling point is in the Doppler spread spectrum and the maximum sampling frequency is equal to the maximum Doppler shift. On the other hand we optimize the function and dimension of basis in CE-BEM respectively ,and obtain the closed solution of the EM based channel estimation differential operator by exploiting the above optimal BEM. Finally, the numerical results and theoretic analysis show that the dimension of basis is mainly depend on the maximum Doppler shift and signal-to-noise ratio (SNR), and if fixing the number of the pilot symbol, the dimension of basis is higher, the modeling error is smaller, while the accuracy of the parameter estimation is reduced, which implies that we need to achieve a tradeoff between the modeling error and the accuracy of the parameter estimation and the basis function influences the accuracy of describing the Doppler spread spectrum after identifying the dimension of the basis.

  20. Vertical Differentiation of Cassava Marketing Channels in Africa

    Directory of Open Access Journals (Sweden)

    Enete, AA.

    2008-01-01

    Full Text Available Farming systems in sub-Saharan Africa are inherently risky because they are fundamentally dependent on vagaries of weather. Sub-Saharan Africa is also a region in crises; poverty, civil strife and HIV/AIDS. Attention must therefore be focused on improving the production and marketing of crops that could thrive under these circumstances. Because of its tolerance of extreme drought and low input use conditions, Cassava is perhaps the best candidate in this regard. And cassava is a basic food staple and a major source of farm income for the people of the region. Efficiency in cassava marketing is a very important determinant of both consumers' living cost and producers' income in Africa. Vertical differentiation of marketing channels improves marketing efficiency. Identified in this paper are factors that drive vertical differentiation of cassava marketing channels. The paper is based on primary data collected within the framework of the Collaborative Study of Cassava in Africa. High population density, good market access conditions, availability of mechanized cassava processing technology and cassava price information stimulate vertical differentiation of the marketing channels.

  1. Laser--Doppler anemometry technique applied to two-phase dispersed flows in a rectangular channel

    International Nuclear Information System (INIS)

    Lee, S.L.; Srinivasan, J.

    1979-01-01

    A new optical technique using Laser--Doppler anemometry has been applied to the local measurement of turbulent upward flow of a dilute water droplet--air two-phase dispersion in a vertical rectangular channel. Individually examined were over 20,000 droplet signals coming from each of a total of ten transversely placed measuring points, the closest of which to the channel wall was 250 μ away from the wall. Two flows of different patterns due to different imposed flow conditions were investigated, one with and the other without a liquid film formed on the channel wall. Reported are the size and number density distribution and the axial and lateral velocity distributions for the droplets as well as the axial and lateral velocity distributions for the air

  2. Channel Choice: A Literature Review

    DEFF Research Database (Denmark)

    Østergaard Madsen, Christian; Kræmmergaard, Pernille

    2015-01-01

    The channel choice branch of e-government studies citizens’ and businesses’ choice of channels for interacting with government, and how government organizations can integrate channels and migrate users towards the most cost-efficient channels. In spite of the valuable contributions offered...

  3. A heat transfer model for evaporating micro-channel coalescing bubble flow

    International Nuclear Information System (INIS)

    Consolini, L.; Thome, J.R.

    2009-01-01

    The current study presents a one-dimensional model of confined coalescing bubble flow for the prediction of micro-channel convective boiling heat transfer. Coalescing bubble flow has recently been identified as one of the characteristic flow patterns to be found in micro-scale systems, occurring at intermediate vapor qualities between the isolated bubble and the fully annular regimes. As two or more bubbles bond under the action of inertia and surface tension, the passage frequency of the bubble liquid slug pair declines, with a redistribution of liquid among the remaining flow structures. Assuming heat transfer to occur only by conduction through the thin evaporating liquid film surrounding individual bubbles, the present model includes a simplified description of the dynamics of the thin film evaporation process that takes into account the added mass transfer by breakup of the bridging liquid slugs. The new model has been confronted against experimental data taken within the coalescing bubble flow mode that have been identified by a diabatic micro-scale flow pattern map. The comparisons for three different fluids (R-134a, R-236fa and R-245fa) gave encouraging results with 83% of the database predicted within a ± 30% error band. (author)

  4. Reconfigurable virtual electrowetting channels.

    Science.gov (United States)

    Banerjee, Ananda; Kreit, Eric; Liu, Yuguang; Heikenfeld, Jason; Papautsky, Ian

    2012-02-21

    Lab-on-a-chip systems rely on several microfluidic paradigms. The first uses a fixed layout of continuous microfluidic channels. Such lab-on-a-chip systems are almost always application specific and far from a true "laboratory." The second involves electrowetting droplet movement (digital microfluidics), and allows two-dimensional computer control of fluidic transport and mixing. The merging of the two paradigms in the form of programmable electrowetting channels takes advantage of both the "continuous" functionality of rigid channels based on which a large number of applications have been developed to date and the "programmable" functionality of digital microfluidics that permits electrical control of on-chip functions. In this work, we demonstrate for the first time programmable formation of virtual microfluidic channels and their continuous operation with pressure driven flows using an electrowetting platform. Experimental, theoretical, and numerical analyses of virtual channel formation with biologically relevant electrolyte solutions and electrically-programmable reconfiguration are presented. We demonstrate that the "wall-less" virtual channels can be formed reliably and rapidly, with propagation rates of 3.5-3.8 mm s(-1). Pressure driven transport in these virtual channels at flow rates up to 100 μL min(-1) is achievable without distortion of the channel shape. We further demonstrate that these virtual channels can be switched on-demand between multiple inputs and outputs. Ultimately, we envision a platform that would provide rapid prototyping of microfluidic concepts and would be capable of a vast library of functions and benefitting applications from clinical diagnostics in resource-limited environments to rapid system prototyping to high throughput pharmaceutical applications.

  5. Mapping of Residues Forming the Voltage Sensor of the Voltage-Dependent Anion-Selective Channel

    Science.gov (United States)

    Thomas, Lorie; Blachly-Dyson, Elizabeth; Colombini, Marco; Forte, Michael

    1993-06-01

    Voltage-gated ion-channel proteins contain "voltage-sensing" domains that drive the conformational transitions between open and closed states in response to changes in transmembrane voltage. We have used site-directed mutagenesis to identify residues affecting the voltage sensitivity of a mitochondrial channel, the voltage-dependent anion-selective channel (VDAC). Although charge changes at many sites had no effect, at other sites substitutions that increased positive charge also increased the steepness of voltage dependance and substitutions that decreased positive charge decreased voltage dependance by an appropriate amount. In contrast to the plasma membrane K^+ and Na^+ channels, these residues are distributed over large parts of the VDAC protein. These results have been used to define the conformational transitions that accompany voltage gating of an ion channel. This gating mechanism requires the movement of large portions of the VDAC protein through the membrane.

  6. TRP Channels as Therapeutic Targets in Diabetes and Obesity

    Directory of Open Access Journals (Sweden)

    Andrea Zsombok

    2016-08-01

    Full Text Available During the last three to four decades the prevalence of obesity and diabetes mellitus has greatly increased worldwide, including in the United States. Both the short- and long-term forecasts predict serious consequences for the near future, and encourage the development of solutions for the prevention and management of obesity and diabetes mellitus. Transient receptor potential (TRP channels were identified in tissues and organs important for the control of whole body metabolism. A variety of TRP channels has been shown to play a role in the regulation of hormone release, energy expenditure, pancreatic function, and neurotransmitter release in control, obese and/or diabetic conditions. Moreover, dietary supplementation of natural ligands of TRP channels has been shown to have potential beneficial effects in obese and diabetic conditions. These findings raised the interest and likelihood for potential drug development. In this mini-review, we discuss possibilities for better management of obesity and diabetes mellitus based on TRP-dependent mechanisms.

  7. A comprehensive search for calcium binding sites critical for TMEM16A calcium-activated chloride channel activity

    Science.gov (United States)

    Tien, Jason; Peters, Christian J; Wong, Xiu Ming; Cheng, Tong; Jan, Yuh Nung; Jan, Lily Yeh; Yang, Huanghe

    2014-01-01

    TMEM16A forms calcium-activated chloride channels (CaCCs) that regulate physiological processes such as the secretions of airway epithelia and exocrine glands, the contraction of smooth muscles, and the excitability of neurons. Notwithstanding intense interest in the mechanism behind TMEM16A-CaCC calcium-dependent gating, comprehensive surveys to identify and characterize potential calcium sensors of this channel are still lacking. By aligning distantly related calcium-activated ion channels in the TMEM16 family and conducting systematic mutagenesis of all conserved acidic residues thought to be exposed to the cytoplasm, we identify four acidic amino acids as putative calcium-binding residues. Alterations of the charge, polarity, and size of amino acid side chains at these sites alter the ability of different divalent cations to activate the channel. Furthermore, TMEM16A mutant channels containing double cysteine substitutions at these residues are sensitive to the redox potential of the internal solution, providing evidence for their physical proximity and solvent accessibility. DOI: http://dx.doi.org/10.7554/eLife.02772.001 PMID:24980701

  8. Charge Fractionalization in the Two-Channel Kondo Effect

    Science.gov (United States)

    Landau, L. Aviad; Cornfeld, Eyal; Sela, Eran

    2018-05-01

    The phenomenon of charge fractionalization describes the emergence of novel excitations with fractional quantum numbers, as predicted in strongly correlated systems such as spin liquids. We elucidate that precisely such an unusual effect may occur in the simplest possible non-Fermi liquid, the two-channel Kondo effect. To bring this concept down to experimental test, we study nonequilibrium transport through a device realizing the charge two-channel Kondo critical point in a recent experiment by Iftikhar et al. [Nature (London) 526, 233 (2015), 10.1038/nature15384]. The shot noise at low voltages is predicted to result in a universal Fano factor e*/e =1 /2 . This allows us to experimentally identify elementary transport processes of emergent fermions carrying half-integer charge.

  9. KV7 potassium channels

    DEFF Research Database (Denmark)

    Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A

    2014-01-01

    Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

  10. Outward Rectification of Voltage-Gated K+ Channels Evolved at Least Twice in Life History.

    Directory of Open Access Journals (Sweden)

    Janin Riedelsberger

    Full Text Available Voltage-gated potassium (K+ channels are present in all living systems. Despite high structural similarities in the transmembrane domains (TMD, this K+ channel type segregates into at least two main functional categories-hyperpolarization-activated, inward-rectifying (Kin and depolarization-activated, outward-rectifying (Kout channels. Voltage-gated K+ channels sense the membrane voltage via a voltage-sensing domain that is connected to the conduction pathway of the channel. It has been shown that the voltage-sensing mechanism is the same in Kin and Kout channels, but its performance results in opposite pore conformations. It is not known how the different coupling of voltage-sensor and pore is implemented. Here, we studied sequence and structural data of voltage-gated K+ channels from animals and plants with emphasis on the property of opposite rectification. We identified structural hotspots that alone allow already the distinction between Kin and Kout channels. Among them is a loop between TMD S5 and the pore that is very short in animal Kout, longer in plant and animal Kin and the longest in plant Kout channels. In combination with further structural and phylogenetic analyses this finding suggests that outward-rectification evolved twice and independently in the animal and plant kingdom.

  11. Preservation of meandering river channels in uniformly aggrading channel belts

    NARCIS (Netherlands)

    Lageweg, W.I. van de; Schuurman, F.; Cohen, K.M.; Dijk, W.M. van; Shimizu, Y.; Kleinhans, M.G.

    2016-01-01

    Channel belt deposits from meandering river systems commonly display an internal architecture of stacked depositional features with scoured basal contacts due to channel and bedform migration across a range of scales. Recognition and correct interpretation of these bounding surfaces is essential to

  12. Multi-channel service retailing: The effects of channel performance satisfaction on behavioral intentions.

    NARCIS (Netherlands)

    Birgelen, van M.; Jong, de A.; Ruyter, de J.C.

    2006-01-01

    Abstract The number of channels that retailers can use interchangeably to provide customer service has increased. We report on a study of clients of a large retail bank that investigates the channel performance satisfaction–behavioral intentions relationship when the traditional service channel

  13. CLC channel function and dysfunction in health and disease

    Directory of Open Access Journals (Sweden)

    Gabriel eStölting

    2014-10-01

    Full Text Available CLC channels and transporters are expressed in most tissues and fulfill diverse functions. There are four human CLC channels, ClC-1, ClC-2, ClC-Ka and ClC-Kb, and five CLC transporters, ClC-3 through -7. Some of the CLC channels additionally associate with accessory subunits. Whereas barttin is mandatory for the functional expression of CLC-K, GlialCam is a facultative subunit of ClC-2 which modifies gating and thus increases the functional variability within the CLC family. Isoform-specific ion conduction and gating properties optimize distinct CLC channels for their cellular tasks. ClC-1 preferentially conducts at negative voltages, and the resulting inward rectification provides a large resting chloride conductance without interference with the muscle action potential. Exclusive opening at voltages negative to the chloride reversal potential allows for ClC-2 to regulate intracellular chloride concentrations. ClC-Ka and ClC-Kb are equally suited for inward and outward currents to support transcellular chloride fluxes. Every human CLC channel gene has been linked to a genetic disease, and studying these mutations has provided much information about the physiological roles and the molecular basis of CLC channel function. Mutations in the gene encoding ClC-1 cause myotonia congenita, a disease characterized by sarcolemmal hyperexcitability and muscle stiffness. Loss-of-function of ClC-Kb/barttin channels in patients suffering from Bartter syndrome identified the determinants of chloride conductances in the limb of Henle. Mutations in CLCN2 were found in patients with CNS disorders but the functional role of this isoform is still not understood. Recent links between ClC-1 and epilepsy and ClC-Ka and heart failure suggested novel cellular functions of these proteins. This review aims to survey the knowledge about physiological and pathophysiological functions of human CLC channels in the light of recent discoveries from biophysical, physiological

  14. Contrasted structuring effects of mesoscale features on the seabird community in the Mozambique Channel

    Science.gov (United States)

    Jaquemet, S.; Ternon, J. F.; Kaehler, S.; Thiebot, J. B.; Dyer, B.; Bemanaja, E.; Marteau, C.; Le Corre, M.

    2014-02-01

    The Mozambique Channel (western Indian Ocean) is a dynamic environment characterised by strong mesoscale features, which influence all biological components of the pelagic ecosystem. We investigated the distribution, abundance and feeding behaviour of seabirds in the Mozambique Channel in relation to physical and biological environmental variables, with a specific interest in mesoscale features. Seabird censuses were conducted in summer and winter during 7 cruises in the southern and northern Mozambique Channel. Tropical species accounted for 49% of the 37 species identified and 97% of the individuals, and species from the sub-Antarctic region constituted 30% of the identifications. The typically tropical sooty tern (Onychoprion fuscata) was the dominant species during all cruises, and overall accounted for 74% of the species observations and 85% of counted birds. Outputs of Generalised Linear Models at the scale of the Mozambique Channel suggested that higher densities of flying and feeding birds occurred in areas with lower sea surface temperatures and lower surface chlorophyll a concentrations. Most of the flocks of feeding birds did not associate with surface schools of fish or marine mammals, but when they did, these flocks were larger, especially when associated with tuna. While tropical species seemed to favour cyclonic eddies, frontal and divergence zones, non-tropical species were more frequently recorded over shelf waters. Sooty terns foraged preferentially in cyclonic eddies where zooplankton, micronekton and tuna schools were abundant. Among other major tropical species, frigatebirds (Fregata spp.) predominated in frontal zones between eddies, where tuna schools also frequently occurred and where geostrophic currents were the strongest. Red-footed boobies (Sula sula) concentrated in divergence zones characterised by low sea level anomalies, low geostrophic currents, and high zooplankton biomass close to the surface. Our results highlight the importance

  15. Lipid ratio as a suitable tool to identify individuals with MetS risk: A case- control study.

    Science.gov (United States)

    Abbasian, Maryam; Delvarianzadeh, Mehri; Ebrahimi, Hossein; Khosravi, Farideh

    2017-11-01

    This study aimed to compare the serum lipids ratio in staff with and without metabolic syndrome (MetS) who were working in Shahroud University of Medical Sciences. This case-control study was conducted in 2015 on 499 personnel aged 30-60 years old. ATP III criteria were used to diagnose patients with MetS. The data were analyzed by using logistic regression and ROC curve. Mean lipid ratio was higher in individuals having the MetS in both sexes compared with those without. In addition, the mean levels of lipid ratios significantly increased with increasing number of MetS components in both sexes. Also it could be concluded that TG/HDL-C ratio is the best marker for the diagnosis of MetS in men and women. Moreover, the cut-off point for the TG/HDL-C was 2.86 in women and 4.03 in men. It was found that for any unit of increases in the TG/HDL-C, the risk of developing the MetS will increase by 2.12 times. TG/HDL-C ratio is found to be the best clinical marker for the diagnosis of MetS compare with other lipid ratios, therefore it is recommended to be used as a feasible tool to identify individuals with MetS risk. Copyright © 2016 Diabetes India. Published by Elsevier Ltd. All rights reserved.

  16. Conclusive identification of quantum channels via monogamy of quantum correlations

    International Nuclear Information System (INIS)

    Kumar, Asutosh; Singha Roy, Sudipto; Pal, Amit Kumar; Prabhu, R.; Sen, Aditi; Sen, Ujjwal

    2016-01-01

    We investigate the action of global noise and local channels, namely, amplitude-damping, phase-damping, and depolarizing channels, on monogamy of quantum correlations, such as negativity and quantum discord, in three-qubit systems. We discuss the monotonic and non-monotonic variation, and robustness of the monogamy scores. By using monogamy scores, we propose a two-step protocol to conclusively identify the noise applied to the quantum system, by using generalized Greenberger–Horne–Zeilinger and generalized W states as resource states. We discuss a possible generalization of the results to higher number of parties. - Highlights: • Monogamy score monotonically decays with noise for generalized GHZ state as input. • Non-monotonically decaying monogamy score with noise for generalized W state as input. • Characterizing the dynamics of monogamy score. • Dynamics terminal quantifying robustness of monogamy score against noise. • Conclusively identifying the type of noise using monogamy score.

  17. Conclusive identification of quantum channels via monogamy of quantum correlations

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Asutosh; Singha Roy, Sudipto; Pal, Amit Kumar [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Prabhu, R. [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Department of Physics, Indian Institute of Technology Patna, Bihta 801103, Bihar (India); Sen, Aditi, E-mail: aditi@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Sen, Ujjwal [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India)

    2016-10-23

    We investigate the action of global noise and local channels, namely, amplitude-damping, phase-damping, and depolarizing channels, on monogamy of quantum correlations, such as negativity and quantum discord, in three-qubit systems. We discuss the monotonic and non-monotonic variation, and robustness of the monogamy scores. By using monogamy scores, we propose a two-step protocol to conclusively identify the noise applied to the quantum system, by using generalized Greenberger–Horne–Zeilinger and generalized W states as resource states. We discuss a possible generalization of the results to higher number of parties. - Highlights: • Monogamy score monotonically decays with noise for generalized GHZ state as input. • Non-monotonically decaying monogamy score with noise for generalized W state as input. • Characterizing the dynamics of monogamy score. • Dynamics terminal quantifying robustness of monogamy score against noise. • Conclusively identifying the type of noise using monogamy score.

  18. Channel selection for simultaneous and proportional myoelectric prosthesis control of multiple degrees-of-freedom

    Science.gov (United States)

    Hwang, Han-Jeong; Hahne, Janne Mathias; Müller, Klaus-Robert

    2014-10-01

    Objective. Recent studies have shown the possibility of simultaneous and proportional control of electrically powered upper-limb prostheses, but there has been little investigation on optimal channel selection. The objective of this study is to find a robust channel selection method and the channel subsets most suitable for simultaneous and proportional myoelectric prosthesis control of multiple degrees-of-freedom (DoFs). Approach. Ten able-bodied subjects and one person with congenital upper-limb deficiency took part in this study, and performed wrist movements with various combinations of two DoFs (flexion/extension and radial/ulnar deviation). During the experiment, high density electromyographic (EMG) signals and the actual wrist angles were recorded with an 8 × 24 electrode array and a motion tracking system, respectively. The wrist angles were estimated from EMG features with ridge regression using the subsets of channels chosen by three different channel selection methods: (1) least absolute shrinkage and selection operator (LASSO), (2) sequential feature selection (SFS), and (3) uniform selection (UNI). Main results. SFS generally showed higher estimation accuracy than LASSO and UNI, but LASSO always outperformed SFS in terms of robustness, such as noise addition, channel shift and training data reduction. It was also confirmed that about 95% of the original performance obtained using all channels can be retained with only 12 bipolar channels individually selected by LASSO and SFS. Significance. From the analysis results, it can be concluded that LASSO is a promising channel selection method for accurate simultaneous and proportional prosthesis control. We expect that our results will provide a useful guideline to select optimal channel subsets when developing clinical myoelectric prosthesis control systems based on continuous movements with multiple DoFs.

  19. Trafficking of Kv2.1 Channels to the Axon Initial Segment by a Novel Nonconventional Secretory Pathway

    DEFF Research Database (Denmark)

    Jensen, Camilla Stampe; Watanabe, Shoji; Stas, Jeroen Ingrid

    2017-01-01

    the localization of Kv2.1 in these two different membrane compartments in cultured rat hippocampal neurons of mixed sex. Our data uncover a unique ability of Kv2.1 channels to use two molecularly distinct trafficking pathways to accomplish this. Somatodendritic Kv2.1 channels are targeted by the conventional...... secretory pathway, whereas axonal Kv2.1 channels are targeted by a nonconventional trafficking pathway independent of the Golgi apparatus. We further identified a new AIS trafficking motif in the C-terminus of Kv2.1, and show that putative phosphorylation sites in this region are critical for the restricted.......SIGNIFICANCE STATEMENT Our study uncovered a novel mechanism that targets the Kv2.1 voltage-gated potassium channel to two distinct trafficking pathways and two distinct subcellular destinations: the somatodendritic plasma membrane and that of the axon initial segment. We also identified a distinct motif, including...

  20. Channel heads in mountain catchments subject to human impact - The Skrzyczne range in Southern Poland

    Science.gov (United States)

    Wrońska-Wałach, Dominika; Żelazny, Mirosław; Małek, Stanisław; Krakowian, Katarzyna; Dąbek, Natalia

    2018-05-01

    Channel heads in mountain catchments are increasingly influenced by human activity. The disturbance of mountain headwater areas in moderate latitudes by the clearing of trees and the associated logging, road building and hydrotechnical constructions contribute to changes in the water cycle and consequently may induce a change in channel head development. Here we examine channel heads in the Beskid Śląski Mts., one of the areas most affected by ecological disaster in the Polish Flysch Carpathians. An ecological disaster associated with the decline of spruce trees in the 1980s and 1990s caused a substantial decrease (of about 50%) in the land area occupied by spruce forest in the Beskid Śląski Mts. As a result, headwater areas were subject to multidirectional changes in the environment. The purpose of this paper is to determine the detailed characteristics of channel heads currently developing in the analyzed headwater areas, as well as to identify independent factors that affect the evolution of channel heads. Geomorphological mapping was conducted in 2012 in the vicinity of springs in the study area. One-way ANOVA was used to determine the significance of differences between mean values calculated for groups identified based on: i) geomorphologic processes (hollows with rock veneer - h, spring niches - sn, gullies - g), ii) location vs. transformation of channel heads (forested areas vs., deforested areas with road constructions). Principal component analysis (PCA) was used to determine the structure and general patterns associated with relationships between the parameters of a channel head and its contribution area, as well as to identify and interpret new (orthogonal) spaces defined using distinct factors. As far as we know, this kind of approach has been never applied before. A total of 80 channel heads surrounding 104 springs were surveyed close to the main ridge in the study area. A total of 14 morphometric parameters were taken into account in this study

  1. Identifying the Individual Differences among Students during Learning and Teaching Process by Science Teachers

    Science.gov (United States)

    Kubat, Ulas

    2018-01-01

    It is important for teachers to know variables such as physical characteristics, intelligence, perception, gender, ability, learning styles, which are individual differences of the learners. An effective and productive learning-teaching process can be planned by considering these individual differences of the students. Since the learners' own…

  2. Bankruptcy of Individuals

    Directory of Open Access Journals (Sweden)

    Ionina M. B.

    2015-10-01

    Full Text Available This article discusses the bankruptcy of individuals under the Federal Law "On Insolvency (Bankruptcy", the Federal Law "On Amendments to the Federal Law "On Insolvency (Bankruptcy" and some legislative acts of the Russian Federation regarding regulation of rehabilitation procedures applicable to an individual debtor. The author analyzes the main ways to address the issue of the bankruptcy of an individual, identifies risks for both a bankrupt and credit institutions

  3. Distribution Channels Conflict and Management

    OpenAIRE

    Kiran, Dr Vasanth; Majumdar, Dr Mousumi; Kishore, Dr Krishna

    2012-01-01

    Relationships in distribution channels tend to be long-term oriented and members of the channel rely on each other to jointly realize their goals by serving buyers. Despite the channels focus on serving buyers, conflicts often arise between channel members because of each members self-interest. When conflicts arise, the perceptions of a channel member based on normative, rational/instrumental, or emotional reasoning will influence relational norms like trust and commitment that characterize t...

  4. A remarkably stable TipE gene cluster: evolution of insect Para sodium channel auxiliary subunits

    Directory of Open Access Journals (Sweden)

    Li Jia

    2011-11-01

    Full Text Available Abstract Background First identified in fruit flies with temperature-sensitive paralysis phenotypes, the Drosophila melanogaster TipE locus encodes four voltage-gated sodium (NaV channel auxiliary subunits. This cluster of TipE-like genes on chromosome 3L, and a fifth family member on chromosome 3R, are important for the optional expression and functionality of the Para NaV channel but appear quite distinct from auxiliary subunits in vertebrates. Here, we exploited available arthropod genomic resources to trace the origin of TipE-like genes by mapping their evolutionary histories and examining their genomic architectures. Results We identified a remarkably conserved synteny block of TipE-like orthologues with well-maintained local gene arrangements from 21 insect species. Homologues in the water flea, Daphnia pulex, suggest an ancestral pancrustacean repertoire of four TipE-like genes; a subsequent gene duplication may have generated functional redundancy allowing gene losses in the silk moth and mosquitoes. Intronic nesting of the insect TipE gene cluster probably occurred following the divergence from crustaceans, but in the flour beetle and silk moth genomes the clusters apparently escaped from nesting. Across Pancrustacea, TipE gene family members have experienced intronic nesting, escape from nesting, retrotransposition, translocation, and gene loss events while generally maintaining their local gene neighbourhoods. D. melanogaster TipE-like genes exhibit coordinated spatial and temporal regulation of expression distinct from their host gene but well-correlated with their regulatory target, the Para NaV channel, suggesting that functional constraints may preserve the TipE gene cluster. We identified homology between TipE-like NaV channel regulators and vertebrate Slo-beta auxiliary subunits of big-conductance calcium-activated potassium (BKCa channels, which suggests that ion channel regulatory partners have evolved distinct lineage

  5. Quantum communication under channel uncertainty

    International Nuclear Information System (INIS)

    Noetzel, Janis Christian Gregor

    2012-01-01

    This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

  6. Joint image reconstruction method with correlative multi-channel prior for x-ray spectral computed tomography

    Science.gov (United States)

    Kazantsev, Daniil; Jørgensen, Jakob S.; Andersen, Martin S.; Lionheart, William R. B.; Lee, Peter D.; Withers, Philip J.

    2018-06-01

    Rapid developments in photon-counting and energy-discriminating detectors have the potential to provide an additional spectral dimension to conventional x-ray grayscale imaging. Reconstructed spectroscopic tomographic data can be used to distinguish individual materials by characteristic absorption peaks. The acquired energy-binned data, however, suffer from low signal-to-noise ratio, acquisition artifacts, and frequently angular undersampled conditions. New regularized iterative reconstruction methods have the potential to produce higher quality images and since energy channels are mutually correlated it can be advantageous to exploit this additional knowledge. In this paper, we propose a novel method which jointly reconstructs all energy channels while imposing a strong structural correlation. The core of the proposed algorithm is to employ a variational framework of parallel level sets to encourage joint smoothing directions. In particular, the method selects reference channels from which to propagate structure in an adaptive and stochastic way while preferring channels with a high data signal-to-noise ratio. The method is compared with current state-of-the-art multi-channel reconstruction techniques including channel-wise total variation and correlative total nuclear variation regularization. Realistic simulation experiments demonstrate the performance improvements achievable by using correlative regularization methods.

  7. Proton channel HVCN1 is required for effector functions of mouse eosinophils

    Science.gov (United States)

    2013-01-01

    Background Proton currents are required for optimal respiratory burst in phagocytes. Recently, HVCN1 was identified as the molecule required for the voltage-gated proton channel activity associated with the respiratory burst in neutrophils. Although there are similarities between eosinophils and neutrophils regarding their mechanism for respiratory burst, the role of proton channels in eosinophil functions has not been fully understood. Results In the present study, we first identified the expression of the proton channel HVCN1 in mouse eosinophils. Furthermore, using HVCN1-deficient eosinophils, we demonstrated important cell-specific effector functions for HVCN1. Similar to HVCN1-deficient neutrophils, HVCN1-deficient eosinophils produced significantly less reactive oxygen species (ROS) upon phorbol myristate acetate (PMA) stimulation compared with WT eosinophils. In contrast to HVCN1-deficient neutrophils, HVCN1-deficient eosinophils did not show impaired calcium mobilization or migration ability compared with wild-type (WT) cells. Uniquely, HVCN1-deficient eosinophils underwent significantly increased cell death induced by PMA stimulation compared with WT eosinophils. The increased cell death was dependent on NADPH oxidase activation, and correlated with the failure of HVCN1-deficient cells to maintain membrane polarization and intracellular pH in the physiological range upon activation. Conclusions Eosinophils require proton channel HVCN1 for optimal ROS generation and prevention of activation-induced cell death. PMID:23705768

  8. Transcriptome Analysis of Individual Stromal Cell Populations Identifies Stroma-Tumor Crosstalk in Mouse Lung Cancer Model

    Directory of Open Access Journals (Sweden)

    Hyejin Choi

    2015-02-01

    Full Text Available Emerging studies have begun to demonstrate that reprogrammed stromal cells play pivotal roles in tumor growth, metastasis, and resistance to therapy. However, the contribution of stromal cells to non-small-cell lung cancer (NSCLC has remained underexplored. We used an orthotopic model of Kras-driven NSCLC to systematically dissect the contribution of specific hematopoietic stromal cells in lung cancer. RNA deep-sequencing analysis of individually sorted myeloid lineage and tumor epithelial cells revealed cell-type-specific differentially regulated genes, indicative of activated stroma. We developed a computational model for crosstalk signaling discovery based on ligand-receptor interactions and downstream signaling networks and identified known and novel tumor-stroma paracrine and tumor autocrine crosstalk-signaling pathways in NSCLC. We provide cellular and molecular insights into components of the lung cancer microenvironment that contribute to carcinogenesis. This study has the potential for development of therapeutic strategies that target tumor-stroma interactions and may complement conventional anti-cancer treatments.

  9. Fluorescence-based high-throughput functional profiling of ligand-gated ion channels at the level of single cells.

    Directory of Open Access Journals (Sweden)

    Sahil Talwar

    Full Text Available Ion channels are involved in many physiological processes and are attractive targets for therapeutic intervention. Their functional properties vary according to their subunit composition, which in turn varies in a developmental and tissue-specific manner and as a consequence of pathophysiological events. Understanding this diversity requires functional analysis of ion channel properties in large numbers of individual cells. Functional characterisation of ligand-gated channels involves quantitating agonist and drug dose-response relationships using electrophysiological or fluorescence-based techniques. Electrophysiology is limited by low throughput and high-throughput fluorescence-based functional evaluation generally does not enable the characterization of the functional properties of each individual cell. Here we describe a fluorescence-based assay that characterizes functional channel properties at single cell resolution in high throughput mode. It is based on progressive receptor activation and iterative fluorescence imaging and delivers >100 dose-responses in a single well of a 384-well plate, using α1-3 homomeric and αβ heteromeric glycine receptor (GlyR chloride channels as a model system. We applied this assay with transiently transfected HEK293 cells co-expressing halide-sensitive yellow fluorescent protein and different GlyR subunit combinations. Glycine EC50 values of different GlyR isoforms were highly correlated with published electrophysiological data and confirm previously reported pharmacological profiles for the GlyR inhibitors, picrotoxin, strychnine and lindane. We show that inter and intra well variability is low and that clustering of functional phenotypes permits identification of drugs with subunit-specific pharmacological profiles. As this method dramatically improves the efficiency with which ion channel populations can be characterized in the context of cellular heterogeneity, it should facilitate systems

  10. THE ASSET PRICE CHANNEL AND ITS ROLE IN MONETARY POLICY TRANSMISSION

    Directory of Open Access Journals (Sweden)

    Dan Horatiu

    2013-07-01

    Full Text Available his paper addresses the subject of the monetary policy transmission mechanism by focusing on the asset price channel, which is the monetary transmission channel responsible for the propagation of the effects induced by the monetary policy decisions made by the central bank that affect the price of assets. We will analyze the asset price channel by taking a close look at its structure, internal processes and the way it delivers monetary policy throughout the economy, ultimately influencing key variables such as the unemployment rate and the levels of consumption and production. After an introduction dealing with the entire monetary transmission mechanism, its role and purposes, we will focus on the particularities of the asset price channel and the two main ways in which it delivers monetary policy decision effects: through changes in Tobin’s q value, which is the ratio between the market value of a given company and its replacement cost of capital, and through the effect of wealth, both of financial and housing nature, on consumption. In our study, we will consider theoretical aspects and observations, but also empirical evidence that highlights that the exact way in which the asset price channel functions may differ from one economy to another due to differences in the structures of the respective economies and differences in psychology and cultural values of consumers. The deep understanding of the asset price transmission channel is very important for any central bank, as this is the channel that governs key aspects of monetary policy transmission linked to the market value of assets and individual wealth. These values have, as we will see in more detail throughout the paper, an important impact on both consumption and investment, two economic actions that can help the economy, but can also prove to be a crucial element in starting and perpetuating an economic crisis.

  11. 3D reconstruction of the source and scale of buried young flood channels on Mars.

    Science.gov (United States)

    Morgan, Gareth A; Campbell, Bruce A; Carter, Lynn M; Plaut, Jeffrey J; Phillips, Roger J

    2013-05-03

    Outflow channels on Mars are interpreted as the product of gigantic floods due to the catastrophic eruption of groundwater that may also have initiated episodes of climate change. Marte Vallis, the largest of the young martian outflow channels (Mars hydrologic activity during a period otherwise considered to be cold and dry. Using data from the Shallow Radar sounder on the Mars Reconnaissance Orbiter, we present a three-dimensional (3D) reconstruction of buried channels on Mars and provide estimates of paleohydrologic parameters. Our work shows that Cerberus Fossae provided the waters that carved Marte Vallis, and it extended an additional 180 kilometers to the east before the emplacement of the younger lava flows. We identified two stages of channel incision and determined that channel depths were more than twice those of previous estimates.

  12. Eight channel fast scalar

    Energy Technology Data Exchange (ETDEWEB)

    Waddoup, W D; Stubbs, R J [Durham Univ. (UK)

    1977-11-01

    An eight channel 64-bit scaler has been constructed with a static CMOS memory. Scaling frequencies are independently variable, at each channel, as are the number of bits/channel. The scaler, when used in conjunction with a multichannel charge to time converter results in a very flexible, gated multichannel ADC.

  13. Calcium-dependent expression of transient receptor potential canonical type 3 channels in patients with chronic kidney disease

    DEFF Research Database (Denmark)

    Liu, Ying; Krueger, Katharina; Hovsepian, Anahit

    2011-01-01

    patients with chronic kidney disease and 19 age- and sex-matched healthy control subjects. TRPC3 channels were identified by immunoblotting using specific antibodies and TRPC3 protein was further confirmed by mass spectrometry. We observed a significant increase of TRPC3 channel protein expression...

  14. Verification of Compliance of Channel and Bundle Power Limits Considering Ageing

    International Nuclear Information System (INIS)

    Kim, In Young; Choi, Yong Won; Lee, Un Chul

    2010-01-01

    In the process of resolving GAI 95G03(Compliance with Bundle and Channel Power Limits) and 01G01(Fuel Management and Surveillance Software Upgrade), Canadian nuclear industry and its regulators upgrade their software like reactor physics code to a level of at least similar to the Industry Standard Toolset (IST). As results, power coefficients of reactivity have large uncertainty had become obvious. If large allowances for uncertainties were needed, analysis must be carried out to ensure reactor safety. To analyze this large uncertainty in power coefficient, uncertainty factors of power coefficient should be identified. Thus in this paper, sensitivity analysis on aging elements is performed by ascertaining envelope of channel power and bundle power. And Compliance with bundle power and channel power limits (GAI 95G03) considering aging effect is verified

  15. Automatic pickup of arrival time of channel wave based on multi-channel constraints

    Science.gov (United States)

    Wang, Bao-Li

    2018-03-01

    Accurately detecting the arrival time of a channel wave in a coal seam is very important for in-seam seismic data processing. The arrival time greatly affects the accuracy of the channel wave inversion and the computed tomography (CT) result. However, because the signal-to-noise ratio of in-seam seismic data is reduced by the long wavelength and strong frequency dispersion, accurately timing the arrival of channel waves is extremely difficult. For this purpose, we propose a method that automatically picks up the arrival time of channel waves based on multi-channel constraints. We first estimate the Jaccard similarity coefficient of two ray paths, then apply it as a weight coefficient for stacking the multichannel dispersion spectra. The reasonableness and effectiveness of the proposed method is verified in an actual data application. Most importantly, the method increases the degree of automation and the pickup precision of the channel-wave arrival time.

  16. Functional modifications of acid-sensing ion channels by ligand-gated chloride channels.

    Directory of Open Access Journals (Sweden)

    Xuanmao Chen

    Full Text Available Together, acid-sensing ion channels (ASICs and epithelial sodium channels (ENaC constitute the majority of voltage-independent sodium channels in mammals. ENaC is regulated by a chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR. Here we show that ASICs were reversibly inhibited by activation of GABA(A receptors in murine hippocampal neurons. This inhibition of ASICs required opening of the chloride channels but occurred with both outward and inward GABA(A receptor-mediated currents. Moreover, activation of the GABA(A receptors modified the pharmacological features and kinetic properties of the ASIC currents, including the time course of activation, desensitization and deactivation. Modification of ASICs by open GABA(A receptors was also observed in both nucleated patches and outside-out patches excised from hippocampal neurons. Interestingly, ASICs and GABA(A receptors interacted to regulate synaptic plasticity in CA1 hippocampal slices. The activation of glycine receptors, which are similar to GABA(A receptors, also modified ASICs in spinal neurons. We conclude that GABA(A receptors and glycine receptors modify ASICs in neurons through mechanisms that require the opening of chloride channels.

  17. A 31-channel MR brain array coil compatible with positron emission tomography.

    Science.gov (United States)

    Sander, Christin Y; Keil, Boris; Chonde, Daniel B; Rosen, Bruce R; Catana, Ciprian; Wald, Lawrence L

    2015-06-01

    Simultaneous acquisition of MR and positron emission tomography (PET) images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (signal to noise ratio [SNR], g-factor) and PET attenuation. The coil design showed an improvement in attenuation by 190% (average) compared with conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical region of interest) compared with a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. © 2014 Wiley Periodicals, Inc.

  18. Coupling of SK channels, L-type Ca2+ channels, and ryanodine receptors in cardiomyocytes.

    Science.gov (United States)

    Zhang, Xiao-Dong; Coulibaly, Zana A; Chen, Wei Chun; Ledford, Hannah A; Lee, Jeong Han; Sirish, Padmini; Dai, Gu; Jian, Zhong; Chuang, Frank; Brust-Mascher, Ingrid; Yamoah, Ebenezer N; Chen-Izu, Ye; Izu, Leighton T; Chiamvimonvat, Nipavan

    2018-03-16

    Small-conductance Ca 2+ -activated K + (SK) channels regulate the excitability of cardiomyocytes by integrating intracellular Ca 2+ and membrane potentials on a beat-to-beat basis. The inextricable interplay between activation of SK channels and Ca 2+ dynamics suggests the pathology of one begets another. Yet, the exact mechanistic underpinning for the activation of cardiac SK channels remains unaddressed. Here, we investigated the intracellular Ca 2+ microdomains necessary for SK channel activation. SK currents coupled with Ca 2+ influx via L-type Ca 2+ channels (LTCCs) continued to be elicited after application of caffeine, ryanodine or thapsigargin to deplete SR Ca 2+ store, suggesting that LTCCs provide the immediate Ca 2+ microdomain for the activation of SK channels in cardiomyocytes. Super-resolution imaging of SK2, Ca v 1.2 Ca 2+ channel, and ryanodine receptor 2 (RyR2) was performed to quantify the nearest neighbor distances (NND) and localized the three molecules within hundreds of nanometers. The distribution of NND between SK2 and RyR2 as well as SK2 and Ca v 1.2 was bimodal, suggesting a spatial relationship between the channels. The activation mechanism revealed by our study paved the way for the understanding of the roles of SK channels on the feedback mechanism to regulate the activities of LTCCs and RyR2 to influence local and global Ca 2+ signaling.

  19. Activation of TRPV1 channels inhibits mechanosensitive Piezo channel activity by depleting membrane phosphoinositides

    Science.gov (United States)

    Borbiro, Istvan; Badheka, Doreen; Rohacs, Tibor

    2015-01-01

    Capsaicin is an activator of the heat-sensitive TRPV1 (transient receptor potential vanilloid 1) ion channels and has been used as a local analgesic. We found that activation of TRPV1 channels with capsaicin either in dorsal root ganglion neurons or in a heterologous expression system inhibited the mechanosensitive Piezo1 and Piezo2 channels by depleting phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and its precursor PI(4)P from the plasma membrane through Ca2+-induced phospholipase Cδ (PLCδ) activation. Experiments with chemically inducible phosphoinositide phosphatases and receptor-induced activation of PLCβ indicated that inhibition of Piezo channels required depletion of both PI(4)P and PI(4,5)P2. The mechanically activated current amplitudes decreased substantially in the excised inside-out configuration, where the membrane patch containing Piezo1 channels is removed from the cell. PI(4,5)P2 and PI(4)P applied to these excised patches inhibited this decrease. Thus, we concluded that Piezo channel activity requires the presence of phosphoinositides, and the combined depletion of PI(4,5)P2 or PI(4)P reduces channel activity. In addition to revealing a role for distinct membrane lipids in mechanosensitive ion channel regulation, these data suggest that inhibition of Piezo2 channels may contribute to the analgesic effect of capsaicin. PMID:25670203

  20. Ionic channels underlying the ventricular action potential in zebrafish embryo.

    Science.gov (United States)

    Alday, Aintzane; Alonso, Hiart; Gallego, Monica; Urrutia, Janire; Letamendia, Ainhoa; Callol, Carles; Casis, Oscar

    2014-06-01

    Over the last years zebrafish has become a popular model in the study of cardiac physiology, pathology and pharmacology. Recently, the application of the 3Rs regulation and the characteristics of the embryo have reduced the use of adult zebrafish use in many studies. However, the zebrafish embryo cardiac physiology is poorly characterized since most works have used indirect techniques and direct recordings of cardiac action potential and ionic currents are scarce. In order to optimize the zebrafish embryo model, we used electrophysiological, pharmacological and immunofluorescence tools to identify the characteristics and the ionic channels involved in the ventricular action potentials of zebrafish embryos. The application of Na(+) or T-type Ca(+2) channel blockers eliminated the cardiac electrical activity, indicating that the action potential upstroke depends on Na(+) and T-type Ca(+2) currents. The plateau phase depends on L-type Ca(+2) channels since it is abolished by specific blockade. The direct channel blockade indicates that the action potential repolarization and diastolic potential depends on ERG K(+) channels. The presence in the embryonic heart of the Nav1.5, Cav1.2, Cav3.2 and ERG channels was also confirmed by immunofluorescence, while the absence of effect of specific blockers and immunostaining indicate that two K(+) repolarizing currents present in human heart, Ito and IKs, are absent in the embryonic zebrafish heart. Our results describe the ionic channels present and its role in the zebrafish embryo heart and support the use of zebrafish embryos to study human diseases and their use for drug testing. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. New Channels, New Possibilities

    DEFF Research Database (Denmark)

    Pieterson, Willem; Ebbers, Wolfgang; Østergaard Madsen, Christian

    2017-01-01

    In this contribution we discuss the characteristics of what we call the fourth generation of public sector service channels: social robots. Based on a review of relevant literature we discuss their characteristics and place into multi-channel models of service delivery. We argue that social robots......-channel models of service delivery. This is especially relevant given the current lack of evaluations of such models, the broad range of channels available, and their different stages of deployment at governments around the world. Nevertheless, social robots offer an potentially very relevant addition...

  2. RadSim: a program to simulate individual particle interactions for educational purposes

    International Nuclear Information System (INIS)

    Verhaegen, Frank; Palefsky, Steven; DeBlois, Francois

    2006-01-01

    A program was developed, RadSim, which can be used to simulate certain individual interactions of photons, electrons, positrons and alpha particles with a single atom for educational purposes. The program can be run in two modes: manual and simulated. In the manual mode, an individual particle undergoing a specified interaction with a target atom can be simulated, which essentially comes down to a graphical evaluation of kinematic equations. In the simulated mode, a preset number of identical particles are allowed to undergo a specified interaction type with a target atom. The exit channel of the interaction is sampled from probability distributions using Monte Carlo methods. The incoming and outgoing particles are visualized and the frequency distribution of the kinematic variables of the exit channel is displayed graphically. It has to be emphasized that RadSim was mainly developed for educational purposes. (note)

  3. Molecular and functional expression of high conductance Ca 2+ activated K+ channels in the eel intestinal epithelium

    DEFF Research Database (Denmark)

    Lionetto, Maria G; Rizzello, Antonia; Giordano, Maria E

    2008-01-01

    Several types of K(+) channels have been identified in epithelial cells. Among them high conductance Ca(2+)-activated K(+) channels (BK channels) are of relevant importance for their involvement in regulatory volume decrease (RVD) response following hypotonic stress. The aim of the present work...... was to investigate the functional and molecular expression of BK in the eel intestine, which is a useful experimental model for cell volume regulation research. In the present paper using rat BK channel-specific primer, a RT-PCR signal of 696 pb cDNA was detected in eel intestine, whole nucleotide sequence showed...... high similarity (83%) to the alpha subunit of BK channel family. BK channel protein expression was verified by immunoblotting and confocal microscopy, while the functional role of BK channels in epithelial ion transport mechanisms and cell volume regulation was examined by electrophysiological...

  4. Degree of anisotropy as an automated indicator of rip channels in high resolution bathymetric models

    Science.gov (United States)

    Trimble, S. M.; Houser, C.; Bishop, M. P.

    2017-12-01

    A rip current is a concentrated seaward flow of water that forms in the surf zone of a beach as a result of alongshore variations in wave breaking. Rips can carry swimmers swiftly into deep water, and they are responsible for hundreds of fatal drownings and thousands of rescues worldwide each year. These currents form regularly alongside hard structures like piers and jetties, and can also form along sandy coasts when there is a three dimensional bar morphology. This latter rip type tends to be variable in strength and location, making them arguably the most dangerous to swimmers and most difficult to identify. These currents form in characteristic rip channels in surf zone bathymetry, in which the primary axis of self-similarity is oriented shore-normal. This paper demonstrates a new method for automating identification of such rip channels in bathymetric digital surface models (DSMs) using bathymetric data collected by various remote sensing methods. Degree of anisotropy is used to detect rip channels and distinguishes between sandbars, rip channels, and other beach features. This has implications for coastal geomorphology theory and safety practices. As technological advances increase access and accuracy of topobathy mapping methods in the surf zone, frequent nearshore bathymetric DSMs could be more easily captured and processed, then analyzed with this method to result in localized, automated, and frequent detection of rip channels. This could ultimately reduce rip-related fatalities worldwide (i) in present mitigation, by identifying the present location of rip channels, (ii) in forecasting, by tracking the channel's evolution through multiple DSMs, and (iii) in rip education by improving local lifeguard knowledge of the rip hazard. Although this paper on applies analysis of degree of anisotropy to the identification of rip channels, this parameter can be applied to multiple facets of barrier island morphological analysis.

  5. Differential expression of the Kv1 voltage-gated potassium channel family in the rat nephron.

    Science.gov (United States)

    Carrisoza-Gaytán, Rolando; Salvador, Carolina; Diaz-Bello, Beatriz; Escobar, Laura I

    2014-10-01

    Several potassium (K(+)) channels contribute to maintaining the resting membrane potential of renal epithelial cells. Apart from buffering the cell membrane potential and cell volume, K(+) channels allow sodium reabsorption in the proximal tubule (PT), K(+) recycling and K(+) reabsorption in the thick ascending limb (TAL) and K(+) secretion and K(+) reabsorption in the distal convoluted tubule (DCT), connecting tubule (CNT) and collecting duct. Previously, we identified Kv.1.1, Kv1.3 and Kv1.6 channels in collecting ducts of the rat inner medulla. We also detected intracellular Kv1.3 channel in the acid secretory intercalated cells, which is trafficked to the apical membrane in response to dietary K(+) to function as a secretory K(+) channel. In this work we sought to characterize the expression of all members of the Kv1 family in the rat nephron. mRNA and protein expression were detected for all Kv1 channels. Immunoblots identified differential expression of each Kv1 in the cortex, outer and inner medulla. Immunofluorescence labeling detected Kv1.5 in Bowman´s capsule and endothelial cells and Kv1.7 in podocytes, endothelial cells and macula densa in glomeruli; Kv1.4, Kv1.5 and Kv1.7 in PT; Kv1.2, Kv1.4 and Kv1.6 in TAL; Kv1.1, Kv1.4 and Kv1.6 in DCT and CNT and Kv1.3 in DCT, and all the Kv1 family in the cortical and medullary collecting ducts. Recently, some hereditary renal syndromes have been attributed to mutations in K(+) channels. Our results expand the repertoire of K(+) channels that contribute to K(+) homeostasis to include the Kv1 family.

  6. Aberrant modulation of a delayed rectifier potassium channel by glutamate in Alzheimer's disease.

    Science.gov (United States)

    Poulopoulou, Cornelia; Markakis, Ioannis; Davaki, Panagiota; Tsaltas, Eleftheria; Rombos, Antonis; Hatzimanolis, Alexandros; Vassilopoulos, Dimitrios

    2010-02-01

    In Alzheimer's disease (AD), potassium channel abnormalities have been reported in both neural and peripheral tissues. Herein, using whole-cell patch-clamp, we demonstrate an aberrant glutamate-dependent modulation of K(V)1.3 channels in T lymphocytes of AD patients. Although intrinsic K(V)1.3 properties in patients were similar to healthy individuals, glutamate (1-1000 microM) failed to yield the hyperpolarizing shift normally observed in K(V)1.3 steady-state inactivation (-4.4+/-2.7 mV in AD vs. -14.3+/-2.5 mV in controls, 10 microM glutamate), resulting in a 4-fold increase of resting channel activity. Specific agonist and antagonist data indicate that this abnormality is due to dysfunction of cognate group II mGluRs. Given that glutamate is present in plasma and that both mGluRs and K(V)1.3 channels regulate T-lymphocyte responsiveness, our finding may account for the presence of immune-associated alterations in AD. Furthermore, if this aberration reflects a corresponding one in neural tissue, it could provide a potential target in AD pathogenesis.

  7. Ion channelling in diamond

    International Nuclear Information System (INIS)

    Derry, T.E.

    1978-06-01

    Diamond is one of the most extreme cases from a channelling point of view, having the smallest thermal vibration amplitude and the lowest atomic number of commonly-encountered crystals. These are the two parameters most important for determining channelling behaviour. It is of consiberable interest therefore to see how well the theories explaining and predicting the channeling properties of other substance, succeed with diamond. Natural diamond, although the best available form for these experiments, is rather variable in its physical properties. Part of the project was devoted to considering and solving the problem of obtaining reproducible results representative of the ideal crystal. Channelling studies were performed on several good crystals, using the Rutherford backscattering method. Critical angles for proton channelling were measured for incident energies from 0.6 to 4.5 MeV, in the three most open axes and three most open planes of the diamond structure, and for α-particle channelling at 0.7 and 1.0 MeV (He + ) in the same axes and planes. For 1.0 MeV protons, the crystal temperature was varied from 20 degrees Celsius to 700 degrees Celsius. The results are presented as curves of backscattered yield versus angle in the region of each axis or plane, and summarised in the form of tables and graphs. Generally the critical angles, axial minimum yields, and temperature dependence are well predicted by the accepted theories. The most valuable overall conclusion is that the mean thermal vibration amplitude of the atoms in a crytical determines the critical approach distance to the channel walls at which an ion can remain channelled, even when this distance is much smaller than the Thomas-Fermi screening distance of the atomic potential, as is the case in diamond. A brief study was made of the radiation damage caused by α-particle bombardment, via its effect on the channelling phenomenon. It was possible to hold damage down to negligible levels during the

  8. Ion Channel Trafficking: Control of Ion Channel Density as a Target for Arrhythmias?

    Directory of Open Access Journals (Sweden)

    Elise Balse

    2017-10-01

    Full Text Available The shape of the cardiac action potential (AP is determined by the contributions of numerous ion channels. Any dysfunction in the proper function or expression of these ion channels can result in a change in effective refractory period (ERP and lead to arrhythmia. The processes underlying the correct targeting of ion channels to the plasma membrane are complex, and have not been fully characterized in cardiac myocytes. Emerging evidence highlights ion channel trafficking as a potential causative factor in certain acquired and inherited arrhythmias, and therapies which target trafficking as opposed to pore block are starting to receive attention. In this review we present the current evidence for the mechanisms which underlie precise control of cardiac ion channel trafficking and targeting.

  9. Random mutagenesis screening indicates the absence of a separate H(+)-sensor in the pH-sensitive Kir channels.

    Science.gov (United States)

    Paynter, Jennifer J; Shang, Lijun; Bollepalli, Murali K; Baukrowitz, Thomas; Tucker, Stephen J

    2010-01-01

    Several inwardly-rectifying (Kir) potassium channels (Kir1.1, Kir4.1 and Kir4.2) are characterised by their sensitivity to inhibition by intracellular H(+) within the physiological range. The mechanism by which these channels are regulated by intracellular pH has been the subject of intense scrutiny for over a decade, yet the molecular identity of the titratable pH-sensor remains elusive. In this study we have taken advantage of the acidic intracellular environment of S. cerevisiae and used a K(+) -auxotrophic strain to screen for mutants of Kir1.1 with impaired pH-sensitivity. In addition to the previously identified K80M mutation, this unbiased screening approach identified a novel mutation (S172T) in the second transmembrane domain (TM2) that also produces a marked reduction in pH-sensitivity through destabilization of the closed-state. However, despite this extensive mutagenic approach, no mutations could be identified which removed channel pH-sensitivity or which were likely to act as a separate H(+) -sensor unique to the pH-sensitive Kir channels. In order to explain these results we propose a model in which the pH-sensing mechanism is part of an intrinsic gating mechanism common to all Kir channels, not just the pH-sensitive Kir channels. In this model, mutations which disrupt this pH-sensor would result in an increase, not reduction, in pH-sensitivity. This has major implications for any future studies of Kir channel pH-sensitivity and explains why formal identification of these pH-sensing residues still represents a major challenge.

  10. Laser warning receiver to identify the wavelength and angle of arrival of incident laser light

    Science.gov (United States)

    Sinclair; Michael B.; Sweatt, William C.

    2010-03-23

    A laser warning receiver is disclosed which has up to hundreds of individual optical channels each optically oriented to receive laser light from a different angle of arrival. Each optical channel has an optical wedge to define the angle of arrival, and a lens to focus the laser light onto a multi-wavelength photodetector for that channel. Each multi-wavelength photodetector has a number of semiconductor layers which are located in a multi-dielectric stack that concentrates the laser light into one of the semiconductor layers according to wavelength. An electrical signal from the multi-wavelength photodetector can be processed to determine both the angle of arrival and the wavelength of the laser light.

  11. Estimation and Mitigation of Channel Non-Reciprocity in Massive MIMO

    Science.gov (United States)

    Raeesi, Orod; Gokceoglu, Ahmet; Valkama, Mikko

    2018-05-01

    Time-division duplex (TDD) based massive MIMO systems rely on the reciprocity of the wireless propagation channels when calculating the downlink precoders based on uplink pilots. However, the effective uplink and downlink channels incorporating the analog radio front-ends of the base station (BS) and user equipments (UEs) exhibit non-reciprocity due to non-identical behavior of the individual transmit and receive chains. When downlink precoder is not aware of such channel non-reciprocity (NRC), system performance can be significantly degraded due to NRC induced interference terms. In this work, we consider a general TDD-based massive MIMO system where frequency-response mismatches at both the BS and UEs, as well as the mutual coupling mismatch at the BS large-array system all coexist and induce channel NRC. Based on the NRC-impaired signal models, we first propose a novel iterative estimation method for acquiring both the BS and UE side NRC matrices and then also propose a novel NRC-aware downlink precoder design which utilizes the obtained estimates. Furthermore, an efficient pilot signaling scheme between the BS and UEs is introduced in order to facilitate executing the proposed estimation method and the NRC-aware precoding technique in practical systems. Comprehensive numerical results indicate substantially improved spectral efficiency performance when the proposed NRC estimation and NRC-aware precoding methods are adopted, compared to the existing state-of-the-art methods.

  12. Flow Oriented Channel Assignment for Multi-radio Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Niu Zhisheng

    2010-01-01

    Full Text Available We investigate channel assignment for a multichannel wireless mesh network backbone, where each router is equipped with multiple interfaces. Of particular interest is the development of channel assignment heuristics for multiple flows. We present an optimization formulation and then propose two iterative flow oriented heuristics for the conflict-free and interference-aware cases, respectively. To maximize the aggregate useful end-to-end flow rates, both algorithms identify and resolve congestion at instantaneous bottleneck link in each iteration. Then the link rate is optimally allocated among contending flows that share this link by solving a linear programming (LP problem. A thorough performance evaluation is undertaken as a function of the number of channels and interfaces/node and the number of contending flows. The performance of our algorithm is shown to be significantly superior to best known algorithm in its class in multichannel limited radio scenarios.

  13. ZAP: a distributed channel assignment algorithm for cognitive radio networks

    Directory of Open Access Journals (Sweden)

    Munaretto Anelise

    2011-01-01

    Full Text Available Abstract We propose ZAP, an algorithm for the distributed channel assignment in cognitive radio (CR networks. CRs are capable of identifying underutilized licensed bands of the spectrum, allowing their reuse by secondary users without interfering with primary users. In this context, efficient channel assignment is challenging as ideally it must be simple, incur acceptable communication overhead, provide timely response, and be adaptive to accommodate frequent changes in the network. Another challenge is the optimization of network capacity through interference minimization. In contrast to related work, ZAP addresses these challenges with a fully distributed approach based only on local (neighborhood knowledge, while significantly reducing computational costs and the number of messages required for channel assignment. Simulations confirm the efficiency of ZAP in terms of (i the performance tradeoff between different metrics and (ii the fast achievement of a suitable assignment solution regardless of network size and density.

  14. Role of voltage-gated L-type Ca2+ channel isoforms for brain function.

    Science.gov (United States)

    Striessnig, J; Koschak, A; Sinnegger-Brauns, M J; Hetzenauer, A; Nguyen, N K; Busquet, P; Pelster, G; Singewald, N

    2006-11-01

    Voltage-gated LTCCs (L-type Ca2+ channels) are established drug targets for the treatment of cardiovascular diseases. LTCCs are also expressed outside the cardiovascular system. In the brain, LTCCs control synaptic plasticity in neurons, and DHP (dihydropyridine) LTCC blockers such as nifedipine modulate brain function (such as fear memory extinction and depression-like behaviour). Voltage-sensitive Ca2+ channels Cav1 .2 and Cav1.3 are the predominant brain LTCCs. As DHPs and other classes of organic LTCC blockers inhibit both isoforms, their pharmacological distinction is impossible and their individual contributions to defined brain functions remain largely unknown. Here, we summarize our recent experiments with two genetically modified mouse strains, which we generated to explore the individual biophysical features of Cav1.2 and Cav1.3 LTCCs and to determine their relative contributions to various physiological peripheral and neuronal functions. The results described here also allow predictions about the pharmacotherapeutic potential of isoform-selective LTCC modulators.

  15. Customer Responses to Channel Migration Strategies Toward the E-channel

    NARCIS (Netherlands)

    Trampe, Debra; Konus, Umut; Verhoef, Peter C.

    2014-01-01

    Many firms stimulate customers to use the E-channel for services, which provokes various consumer responses to such limits on their freedom of choice. In a study on bank customers, we examine the extent of customer reactance in response to various E-channel migration strategies, the potential of

  16. Multi-rate control over AWGN channels via analog joint source-channel coding

    KAUST Repository

    Khina, Anatoly; Pettersson, Gustav M.; Kostina, Victoria; Hassibi, Babak

    2017-01-01

    We consider the problem of controlling an unstable plant over an additive white Gaussian noise (AWGN) channel with a transmit power constraint, where the signaling rate of communication is larger than the sampling rate (for generating observations and applying control inputs) of the underlying plant. Such a situation is quite common since sampling is done at a rate that captures the dynamics of the plant and which is often much lower than the rate that can be communicated. This setting offers the opportunity of improving the system performance by employing multiple channel uses to convey a single message (output plant observation or control input). Common ways of doing so are through either repeating the message, or by quantizing it to a number of bits and then transmitting a channel coded version of the bits whose length is commensurate with the number of channel uses per sampled message. We argue that such “separated source and channel coding” can be suboptimal and propose to perform joint source-channel coding. Since the block length is short we obviate the need to go to the digital domain altogether and instead consider analog joint source-channel coding. For the case where the communication signaling rate is twice the sampling rate, we employ the Archimedean bi-spiral-based Shannon-Kotel'nikov analog maps to show significant improvement in stability margins and linear-quadratic Gaussian (LQG) costs over simple schemes that employ repetition.

  17. Multi-rate control over AWGN channels via analog joint source-channel coding

    KAUST Repository

    Khina, Anatoly

    2017-01-05

    We consider the problem of controlling an unstable plant over an additive white Gaussian noise (AWGN) channel with a transmit power constraint, where the signaling rate of communication is larger than the sampling rate (for generating observations and applying control inputs) of the underlying plant. Such a situation is quite common since sampling is done at a rate that captures the dynamics of the plant and which is often much lower than the rate that can be communicated. This setting offers the opportunity of improving the system performance by employing multiple channel uses to convey a single message (output plant observation or control input). Common ways of doing so are through either repeating the message, or by quantizing it to a number of bits and then transmitting a channel coded version of the bits whose length is commensurate with the number of channel uses per sampled message. We argue that such “separated source and channel coding” can be suboptimal and propose to perform joint source-channel coding. Since the block length is short we obviate the need to go to the digital domain altogether and instead consider analog joint source-channel coding. For the case where the communication signaling rate is twice the sampling rate, we employ the Archimedean bi-spiral-based Shannon-Kotel\\'nikov analog maps to show significant improvement in stability margins and linear-quadratic Gaussian (LQG) costs over simple schemes that employ repetition.

  18. Channel sialic acids limit hERG channel activity during the ventricular action potential.

    Science.gov (United States)

    Norring, Sarah A; Ednie, Andrew R; Schwetz, Tara A; Du, Dongping; Yang, Hui; Bennett, Eric S

    2013-02-01

    Activity of human ether-a-go-go-related gene (hERG) 1 voltage-gated K(+) channels is responsible for portions of phase 2 and phase 3 repolarization of the human ventricular action potential. Here, we questioned whether and how physiologically and pathophysiologically relevant changes in surface N-glycosylation modified hERG channel function. Voltage-dependent hERG channel gating and activity were evaluated as expressed in a set of Chinese hamster ovary (CHO) cell lines under conditions of full glycosylation, no sialylation, no complex N-glycans, and following enzymatic deglycosylation of surface N-glycans. For each condition of reduced glycosylation, hERG channel steady-state activation and inactivation relationships were shifted linearly by significant depolarizing ∼9 and ∼18 mV, respectively. The hERG window current increased significantly by 50-150%, and the peak shifted by a depolarizing ∼10 mV. There was no significant change in maximum hERG current density. Deglycosylated channels were significantly more active (20-80%) than glycosylated controls during phases 2 and 3 of action potential clamp protocols. Simulations of hERG current and ventricular action potentials corroborated experimental data and predicted reduced sialylation leads to a 50-70-ms decrease in action potential duration. The data describe a novel mechanism by which hERG channel gating is modulated through physiologically and pathophysiologically relevant changes in N-glycosylation; reduced channel sialylation increases hERG channel activity during the action potential, thereby increasing the rate of action potential repolarization.

  19. Dream content: Individual and generic aspects.

    Science.gov (United States)

    Hobson, Allan; Kahn, David

    2007-12-01

    Dream reports were collected from normal subjects in an effort to determine the degree to which dream reports can be used to identify individual dreamers. Judges were asked to group the reports by their authors. The judges scored the reports correctly at chance levels. This finding indicated that dreams may be at least as much like each other as they are the signature of individual dreamers. Our results suggest that dream reports cannot be used to identify the individuals who produced them when identifiers like names and gender of friends and family members are removed from the dream report. In addition to using dreams to learn about an individual, we must look at dreams as telling us about important common or generic aspects of human consciousness.

  20. Course on Ionic Channels

    CERN Document Server

    1986-01-01

    This book is based on a series of lectures for a course on ionic channels held in Santiago, Chile, on November 17-20, 1984. It is intended as a tutorial guide on the properties, function, modulation, and reconstitution of ionic channels, and it should be accessible to graduate students taking their first steps in this field. In the presentation there has been a deliberate emphasis on the spe­ cific methodologies used toward the understanding of the workings and function of channels. Thus, in the first section, we learn to "read" single­ channel records: how to interpret them in the theoretical frame of kinetic models, which information can be extracted from gating currents in re­ lation to the closing and opening processes, and how ion transport through an open channel can be explained in terms of fluctuating energy barriers. The importance of assessing unequivocally the origin and purity of mem­ brane preparations and the use of membrane vesicles and optical tech­ niques in the stUGY of ionic channels a...

  1. Quantum communication under channel uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Noetzel, Janis Christian Gregor

    2012-09-06

    This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

  2. Phosphatidylinositol-4,5-bisphosphate is required for KCNQ1/KCNE1 channel function but not anterograde trafficking.

    Directory of Open Access Journals (Sweden)

    Alice A Royal

    Full Text Available The slow delayed-rectifier potassium current (IKs is crucial for human cardiac action potential repolarization. The formation of IKs requires co-assembly of the KCNQ1 α-subunit and KCNE1 β-subunit, and mutations in either of these subunits can lead to hereditary long QT syndrome types 1 and 5, respectively. It is widely recognised that the KCNQ1/KCNE1 (Q1/E1 channel requires phosphatidylinositol-4,5-bisphosphate (PIP2 binding for function. We previously identified a cluster of basic residues in the proximal C-terminus of KCNQ1 that form a PIP2/phosphoinositide binding site. Upon charge neutralisation of these residues we found that the channel became more retained in the endoplasmic reticulum, which raised the possibility that channel-phosphoinositide interactions could play a role in channel trafficking. To explore this further we used a chemically induced dimerization (CID system to selectively deplete PIP2 and/or phosphatidylinositol-4-phosphate (PI(4P at the plasma membrane (PM or Golgi, and we subsequently monitored the effects on both channel trafficking and function. The depletion of PIP2 and/or PI(4P at either the PM or Golgi did not alter channel cell-surface expression levels. However, channel function was extremely sensitive to the depletion of PIP2 at the PM, which is in contrast to the response of other cardiac potassium channels tested (Kir2.1 and Kv11.1. Surprisingly, when using the CID system IKs was dramatically reduced even before dimerization was induced, highlighting limitations regarding the utility of this system when studying processes highly sensitive to PIP2 depletion. In conclusion, we identify that the Q1/E1 channel does not require PIP2 or PI(4P for anterograde trafficking, but is heavily reliant on PIP2 for channel function once at the PM.

  3. XPM-induced degradation of multilevel phase modulated channel caused by neighboring NRZ modulated channels

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee; Schiellerup, G.; Peucheret, Christophe

    2008-01-01

    The impact of XPM from NRZ modulated channels on an 8-level phase modulated channel in a WDM system was investigated. Requirements on launch power are found. 400 km transmission was achieved with negligible penalty.......The impact of XPM from NRZ modulated channels on an 8-level phase modulated channel in a WDM system was investigated. Requirements on launch power are found. 400 km transmission was achieved with negligible penalty....

  4. User's Guide for Mixed-Size Sediment Transport Model for Networks of One-Dimensional Open Channels

    Science.gov (United States)

    Bennett, James P.

    2001-01-01

    use of the model as to numbers of channels, channel junctions, cross sections per channel, or points defining the cross sections. Following completion of the simulation computations, the GUI accommodates display of longitudinal plots of either bed elevation and size composition, or of transport rate and size composition of the various components, for individual channels and selected times during the simulation period. For individual cross sections, the GUI also allows display of time series of transport rate and size composition of the various components and of bed elevation and size composition.

  5. The impact of the multi-channel retail mix on online store choice: Does online experience matter?

    OpenAIRE

    Melis, Kristina; Campo, Katia; Breugelmans, Els; Lamey, Lien

    2015-01-01

    More and more grocery retailers are becoming multi-channel retailers, as they are opening an online alternative next to their traditional offline supermarkets. While the number of multi-channel grocery shoppers is also expanding at a fast growth rate, there are still large differences in online shopping frequency, and as a result, in the levels of experience with buying in the online grocery channel. This study wants to (i) identify the underlying drivers of online store choice and (ii) explo...

  6. Structural determinants of PIP(2) regulation of inward rectifier K(ATP) channels.

    Science.gov (United States)

    Shyng, S L; Cukras, C A; Harwood, J; Nichols, C G

    2000-11-01

    Phosphatidylinositol 4,5-bisphosphate (PIP(2)) activates K(ATP) and other inward rectifier (Kir) channels. To determine residues important for PIP(2) regulation, we have systematically mutated each positive charge in the COOH terminus of Kir6.2 to alanine. The effects of these mutations on channel function were examined using (86)Rb efflux assays on intact cells and inside-out patch-clamp methods. Both methods identify essentially the same basic residues in two narrow regions (176-222 and 301-314) in the COOH terminus that are important for the maintenance of channel function and interaction with PIP(2). Only one residue (R201A) simultaneously affected ATP and PIP(2) sensitivity, which is consistent with the notion that these ligands, while functionally competitive, are unlikely to bind to identical sites. Strikingly, none of 13 basic residues in the terminal portion (residues 315-390) of the COOH terminus affected channel function when neutralized. The data help to define the structural requirements for PIP(2) sensitivity of K(ATP) channels. Moreover, the regions and residues defined in this study parallel those uncovered in recent studies of PIP(2) sensitivity in other inward rectifier channels, indicating a common structural basis for PIP(2) regulation.

  7. Methodologies and technologies for life assessment and management of coolant channels of Indian pressurised heavy water reactors

    International Nuclear Information System (INIS)

    Rupani, B.B.; Sinha, S.K.; Sinha, R.K.

    2002-01-01

    coolant channels and various research publications in international journals formed the bases for evolution of the above safety methodologies. Today, the analytical models together with the safety evaluation methodologies have become an important tool for assessing fitness for service of individual pressure tube in different reactors. Apart from developing the above analytical tools and methodologies for safety evaluation, several systems and tools have been designed and developed to cater for the activities like remote inspection, online integrity monitoring and life extension etc., of our life management programme of coolant channel. Amongst the systems developed for remote inspection of the coolant channel such as Dry Visual Inspection System (DRYVIS), BARC Inspection System(BARCIS) and Hydraulic Remote Inside Diameter Measurement System (HYRIM) etc., BARCIS is more versatile in terms of its capability to carry out different type of measurements. Inspection of the coolant channel by BARCIS has been incorporated as an important activity in our life management programme of the coolant channel. A non destructive diagnostic technique based on the principle of vibration measurement has been developed to identify the contact between the pressure tube and calandria tube. This technique called 'Non Intrusive Vibration Diagnostic Technique (NIVDT)' is being used as a tool to screen the vulnerable pressure tubes so as reduce the reduce the inspection load. Tools and techniques developed for online integrity monitoring includes Sliver Sample Scraping Tool (SSST). At present, scraping operation can be carried out in both the dry and the wet channel of operating reactor. The development of SSST is intended for taking nondestructively sliver samples from the operating coolant channel. These sliver samples are then analysed to get hydrogen content in them. Measured hydrogen content helps not only in predicting the operating life of a coolant channel but also in improving the

  8. Hydrodynamics and Connectivity of Channelized Floodplains: Insights from the Meandering East Fork White River, Indiana, USA

    Science.gov (United States)

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

    2017-12-01

    High resolution topography reveals that meandering river floodplains in Indiana commonly have networks of channels. These floodplain channel networks are most prevalent in agricultural, low-gradient, wide floodplains. It appears that these networks are formed when floodplain channels connect oxbows to each other and the main river channel. Collectively, the channels in the floodplain create an interconnected network of pathways that convey water beginning at flows less than bankfull, and as stage increases, more of the floodplain becomes dissected by floodplain channels. In this work, we quantify the hydrodynamics and connectivity of the flow on the floodplain and in the main channel of the East Fork White River near Seymour, Indiana, USA. We constructed a two-dimensional numerical model using HECRAS of the river-floodplain system from LiDAR data and from main-channel river bathymetry to elucidate the behaviour of these floodplain channels across a range of flows. Model calibration and verification data included stage from a USGS gage, high-water marks at a high and medium flow, and an aerial photograph of inundation in the floodplain channels. The numerical model simulated flow depth and velocity, which was used to quantify connectivity of the floodplain channels, exchange between the main channel and floodplain channels, and residence time of water on the floodplain. Model simulations suggest that the floodplain channels convey roughly 50% of the total flow at what is typically considered "bankfull" flow. Overall, we present a process-based approach for analyzing complex floodplain-river systems where an individual floodplain-river system can be distilled down to a set of characteristic curves. Notably, we map the East Fork White River system to exchange-residence time space and argue that this characterization forms the basis for thinking about morphologic evolution (e.g., sediment deposition and erosion) and biogeochemistry (e.g., nitrate removal) in floodplain

  9. Automated identification of stream-channel geomorphic features from high‑resolution digital elevation models in West Tennessee watersheds

    Science.gov (United States)

    Cartwright, Jennifer M.; Diehl, Timothy H.

    2017-01-17

    High-resolution digital elevation models (DEMs) derived from light detection and ranging (lidar) enable investigations of stream-channel geomorphology with much greater precision than previously possible. The U.S. Geological Survey has developed the DEM Geomorphology Toolbox, containing seven tools to automate the identification of sites of geomorphic instability that may represent sediment sources and sinks in stream-channel networks. These tools can be used to modify input DEMs on the basis of known locations of stormwater infrastructure, derive flow networks at user-specified resolutions, and identify possible sites of geomorphic instability including steep banks, abrupt changes in channel slope, or areas of rough terrain. Field verification of tool outputs identified several tool limitations but also demonstrated their overall usefulness in highlighting likely sediment sources and sinks within channel networks. In particular, spatial clusters of outputs from multiple tools can be used to prioritize field efforts to assess and restore eroding stream reaches.

  10. On the secrecy capacity of the wiretap channel with imperfect main channel estimation

    KAUST Repository

    Rezki, Zouheir

    2014-10-01

    We study the secrecy capacity of fast fading channels under imperfect main channel (between the transmitter and the legitimate receiver) estimation at the transmitter. Lower and upper bounds on the ergodic secrecy capacity are derived for a class of independent identically distributed (i.i.d.) fading channels. The achievable rate follows from a standard wiretap code in which a simple on-off power control is employed along with a Gaussian input. The upper bound is obtained using an appropriate correlation scheme of the main and eavesdropper channels and is the best known upper bound so far. The upper and lower bounds coincide with recently derived ones in case of perfect main CSI. Furthermore, the upper bound is tight in case of no main CSI, where the secrecy capacity is equal to zero. Asymptotic analysis at high and low signal-to-noise ratio (SNR) is also given. At high SNR, we show that the capacity is bounded by providing upper and lower bounds that depend on the channel estimation error. At low SNR, however, we prove that the secrecy capacity is asymptotically equal to the capacity of the main channel as if there were no secrecy constraint. Numerical results are provided for i.i.d. Rayleigh fading channels.

  11. Comparison of methods used to identify superior individuals in genomic selection in plant breeding.

    Science.gov (United States)

    Bhering, L L; Junqueira, V S; Peixoto, L A; Cruz, C D; Laviola, B G

    2015-09-10

    The aim of this study was to evaluate different methods used in genomic selection, and to verify those that select a higher proportion of individuals with superior genotypes. Thus, F2 populations of different sizes were simulated (100, 200, 500, and 1000 individuals) with 10 replications each. These consisted of 10 linkage groups (LG) of 100 cM each, containing 100 equally spaced markers per linkage group, of which 200 controlled the characteristics, defined as the 20 initials of each LG. Genetic and phenotypic values were simulated assuming binomial distribution of effects for each LG, and the absence of dominance. For phenotypic values, heritabilities of 20, 50, and 80% were considered. To compare methodologies, the analysis processing time, coefficient of coincidence (selection of 5, 10, and 20% of superior individuals), and Spearman correlation between true genetic values, and the genomic values predicted by each methodology were determined. Considering the processing time, the three methodologies were statistically different, rrBLUP was the fastest, and Bayesian LASSO was the slowest. Spearman correlation revealed that the rrBLUP and GBLUP methodologies were equivalent, and Bayesian LASSO provided the lowest correlation values. Similar results were obtained in coincidence variables among the individuals selected, in which Bayesian LASSO differed statistically and presented a lower value than the other methodologies. Therefore, for the scenarios evaluated, rrBLUP is the best methodology for the selection of genetically superior individuals.

  12. Dielectrophoretic analysis of changes in cytoplasmic ion levels due to ion channel blocker action reveals underlying differences between drug-sensitive and multidrug-resistant leukaemic cells

    International Nuclear Information System (INIS)

    Duncan, L; Shelmerdine, H; Hughes, M P; Coley, H M; Huebner, Y; Labeed, F H

    2008-01-01

    Dielectrophoresis (DEP)-the motion of particles in non-uniform AC fields-has been used in the investigation of cell electrophysiology. The technique offers the advantages of rapid determination of the conductance and capacitance of membrane and cytoplasm. However, it is unable to directly determine the ionic strengths of individual cytoplasmic ions, which has potentially limited its application in assessing cell composition. In this paper, we demonstrate how dielectrophoresis can be used to investigate the cytoplasmic ion composition by using ion channel blocking agents. By blocking key ion transporters individually, it is possible to determine their overall contribution to the free ions in the cytoplasm. We use this technique to evaluate the relative contributions of chloride, potassium and calcium ions to the cytoplasmic conductivities of drug sensitive and resistant myelogenous leukaemic (K562) cells in order to determine the contributions of individual ion channel activity in mediating multi-drug resistance in cancer. Results indicate that whilst K + and Ca 2+ levels were extremely similar between sensitive and resistant lines, levels of Cl - were elevated by three times to that in the resistant line, implying increased chloride channel activity. This result is in line with current theories of MDR, and validates the use of ion channel blockers with DEP to investigate ion channel function. (note)

  13. Scorpion Toxins Specific for Potassium (K+ Channels: A Historical Overview of Peptide Bioengineering

    Directory of Open Access Journals (Sweden)

    Zachary L. Bergeron

    2012-11-01

    Full Text Available Scorpion toxins have been central to the investigation and understanding of the physiological role of potassium (K+ channels and their expansive function in membrane biophysics. As highly specific probes, toxins have revealed a great deal about channel structure and the correlation between mutations, altered regulation and a number of human pathologies. Radio- and fluorescently-labeled toxin isoforms have contributed to localization studies of channel subtypes in expressing cells, and have been further used in competitive displacement assays for the identification of additional novel ligands for use in research and medicine. Chimeric toxins have been designed from multiple peptide scaffolds to probe channel isoform specificity, while advanced epitope chimerization has aided in the development of novel molecular therapeutics. Peptide backbone cyclization has been utilized to enhance therapeutic efficiency by augmenting serum stability and toxin half-life in vivo as a number of K+-channel isoforms have been identified with essential roles in disease states ranging from HIV, T-cell mediated autoimmune disease and hypertension to various cardiac arrhythmias and Malaria. Bioengineered scorpion toxins have been monumental to the evolution of channel science, and are now serving as templates for the development of invaluable experimental molecular therapeutics.

  14. Risk Modelling for Passages in Approach Channel

    Directory of Open Access Journals (Sweden)

    Leszek Smolarek

    2013-01-01

    Full Text Available Methods of multivariate statistics, stochastic processes, and simulation methods are used to identify and assess the risk measures. This paper presents the use of generalized linear models and Markov models to study risks to ships along the approach channel. These models combined with simulation testing are used to determine the time required for continuous monitoring of endangered objects or period at which the level of risk should be verified.

  15. Comparative evaluation of three heat transfer enhancement strategies in a grooved channel

    Energy Technology Data Exchange (ETDEWEB)

    Herman, C.; Kang, E. [Dept. of Mechanical Engineering, Johns Hopkins Univ., Baltimore, MD (United States)

    2001-09-01

    Results of a comparative evaluation of three heat transfer enhancement strategies for forced convection cooling of a parallel plate channel populated with heated blocks, representing electronic components mounted on printed circuit boards, are reported. Heat transfer in the reference geometry, the asymmetrically heated parallel plate channel, is compared with that for the basic grooved channel, and the same geometry enhanced by cylinders and vanes placed above the downstream edge of each heated block. In addition to conventional heat transfer and pressure drop measurements, holographic interferometry combined with high-speed cinematography was used to visualize the unsteady temperature fields in the self-sustained oscillatory flow. The locations of increased heat transfer within one channel periodicity depend on the enhancement technique applied, and were identified by analyzing the unsteady temperature distributions visualized by holographic interferometry. This approach allowed gaining insight into the mechanisms responsible for heat transfer enhancement. Experiments were conducted at moderate flow velocities in the laminar, transitional and turbulent flow regimes. Reynolds numbers were varied in the range Re = 200-6500, corresponding to flow velocities from 0.076 to 2.36 m/s. Flow oscillations were first observed between Re = 1050 and 1320 for the basic grooved channel, and around Re = 350 and 450 for the grooved channels equipped with cylinders and vanes, respectively. At Reynolds numbers above the onset of oscillations and in the transitional flow regime, heat transfer rates in the investigated grooved channels exceeded the performance of the reference geometry, the asymmetrically heated parallel plate channel. Heat transfer in the grooved channels enhanced with cylinders and vanes showed an increase by a factor of 1.2-1.8 and 1.5-3.5, respectively, when compared to data obtained for the basic grooved channel; however, the accompanying pressure drop penalties

  16. Identifying genetic relatives without compromising privacy.

    Science.gov (United States)

    He, Dan; Furlotte, Nicholas A; Hormozdiari, Farhad; Joo, Jong Wha J; Wadia, Akshay; Ostrovsky, Rafail; Sahai, Amit; Eskin, Eleazar

    2014-04-01

    The development of high-throughput genomic technologies has impacted many areas of genetic research. While many applications of these technologies focus on the discovery of genes involved in disease from population samples, applications of genomic technologies to an individual's genome or personal genomics have recently gained much interest. One such application is the identification of relatives from genetic data. In this application, genetic information from a set of individuals is collected in a database, and each pair of individuals is compared in order to identify genetic relatives. An inherent issue that arises in the identification of relatives is privacy. In this article, we propose a method for identifying genetic relatives without compromising privacy by taking advantage of novel cryptographic techniques customized for secure and private comparison of genetic information. We demonstrate the utility of these techniques by allowing a pair of individuals to discover whether or not they are related without compromising their genetic information or revealing it to a third party. The idea is that individuals only share enough special-purpose cryptographically protected information with each other to identify whether or not they are relatives, but not enough to expose any information about their genomes. We show in HapMap and 1000 Genomes data that our method can recover first- and second-order genetic relationships and, through simulations, show that our method can identify relationships as distant as third cousins while preserving privacy.

  17. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter

    2014-01-01

    About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...... drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate...... that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K(+) channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure...

  18. Calcium-Activated Cl- Channel: Insights on the Molecular Identity in Epithelial Tissues.

    Science.gov (United States)

    Rottgen, Trey S; Nickerson, Andrew J; Rajendran, Vazhaikkurichi M

    2018-05-10

    Calcium-activated chloride secretion in epithelial tissues has been described for many years. However, the molecular identity of the channel responsible for the Ca 2+ -activated Cl − secretion in epithelial tissues has remained a mystery. More recently, TMEM16A has been identified as a new putative Ca 2+ -activated Cl − channel (CaCC). The primary goal of this article will be to review the characterization of TMEM16A, as it relates to the physical structure of the channel, as well as important residues that confer voltage and Ca 2+ -sensitivity of the channel. This review will also discuss the role of TMEM16A in epithelial physiology and potential associated-pathophysiology. This will include discussion of developed knockout models that have provided much needed insight on the functional localization of TMEM16A in several epithelial tissues. Finally, this review will examine the implications of the identification of TMEM16A as it pertains to potential novel therapies in several pathologies.

  19. Emission channeling studies of Indium Phosphide at low temperatures at CERN-ISOLDE

    CERN Document Server

    Amorim, Lígia Marina; Wahl, Ulrich

    $^{111}$In radioactive atoms were implanted into a single crystal of InP. After annealing for lattice recovery of implantation defects, the lattice site location of $^{111}$In/$^{111}$Cd was studied with the emission channeling technique, from room temperature ( 300K) down to 50K at CERN-ISOLDE. This work aims to test a recently developed cooling station for emission channeling experiments. InP is a material with a relatively low Debye temperature, where significant changes of atomic vibrations are expected with temperature, thus providing an ideal test ground of the effects, which can be expected to influence the data, i.e., de-channeling from lattice vibration and changes of the root mean square displacement (r.m.s.) of the atomic position of the probe atom. In the future we intend to apply these studies to monitor individual impurities or lattice constituents, with temperature, upon phase transitions as well as studying lattice sites of dopants implanted at low temperature.

  20. Channel Estimation in DCT-Based OFDM

    Science.gov (United States)

    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. PMID:24757439