WorldWideScience

Sample records for channels selectively control

  1. A general method for selecting quantum channel for bidirectional controlled state teleportation and other schemes of controlled quantum communication

    Science.gov (United States)

    Thapliyal, Kishore; Verma, Amit; Pathak, Anirban

    2015-12-01

    Recently, a large number of protocols for bidirectional controlled state teleportation (BCST) have been proposed using n-qubit entangled states (nin {5,6,7}) as quantum channel. Here, we propose a general method of selecting multiqubit (n>4) quantum channels suitable for BCST and show that all the channels used in the existing protocols of BCST can be obtained using the proposed method. Further, it is shown that the quantum channels used in the existing protocols of BCST form only a negligibly small subset of the set of all the quantum channels that can be constructed using the proposed method to implement BCST. It is also noted that all these quantum channels are also suitable for controlled bidirectional remote state preparation. Following the same logic, methods for selecting quantum channels for other controlled quantum communication tasks, such as controlled bidirectional joint remote state preparation and controlled quantum dialogue, are also provided.

  2. The mechanosensory calcium-selective ion channel: key component of a plasmalemmal control centre?

    Science.gov (United States)

    Pickard, B. G.; Ding, J. P.

    1993-01-01

    Mechanosensory calcium-selective ion channels probably serve to detect not only mechanical stress but also electrical, thermal, and diverse chemical stimuli. Because all stimuli result in a common output, most notably a shift in second messenger calcium concentration, the channels are presumed to serve as signal integrators. Further, insofar as second messenger calcium in turn gives rise to mechanical, electrical, and diverse chemical changes, the channels are postulated to initiate regulatory feedbacks. It is proposed that the channels and the feedback loops play a wide range of roles in regulating normal plant function, as well as in mediating disturbance of normal function by environmental stressors and various pathogens. In developing evidence for the physiological performance of the channel, a model for a cluster of regulatory plasmalemmal proteins and cytoskeletal elements grouped around a set of wall-to-membrane and transmembrane linkers has proved useful. An illustration of how the model might operate is presented. It is founded on the demonstration that several xenobiotics interfere both with normal channel behaviour and with gravitropic reception. Accordingly, the first part of the illustration deals with how the channels and the control system within which they putatively operate might initiate gravitropism. Assuming that gravitropism is an asymmetric expression of growth, the activities of the channels and the plasmalemmal control system are extrapolated to account for regulation of both rate and allometry of cell expansion. Finally, it is discussed how light, hormones, redox agents and herbicides could in principle affect growth via the putative plasmalemmal control cluster or centre.

  3. Control of the selectivity of the aquaporin water channel family by global orientational tuning

    DEFF Research Database (Denmark)

    Jensen, Morten Østergaard; Tajkhorshid, E.; Nollert, P.;

    2002-01-01

    Aquaporins are transmembrane channels found in cell membranes of all life forms. We examine their apparently paradoxical property, facilitation of efficient permeation of water while excluding protons, which is of critical importance to preserving the electrochemical potential across the cell......, this dictates opposite orientations of water molecules in the two halves of the channel, and thus prevents the formation of a "proton wire," while permitting rapid water diffusion. Both simulations and observations revealed a more regular distribution of channel water and an increased water permeability...... membrane. We have determined the structure of the Escherichia coli aquaglyceroporin GlpF with bound water, in native (2.7 angstroms) and in W48F/F200T mutant (2.1 angstroms) forms, and carried out 12-nanosecond molecular dynamics simulations that define the spatial and temporal probability distribution...

  4. Control of the Selectivity of the Aquaporin Water Channel Family by Global Orientational Tuning

    Science.gov (United States)

    Tajkhorshid, Emad; Nollert, Peter; Jensen, Morten Ø.; Miercke, Larry J. W.; O'Connell, Joseph; Stroud, Robert M.; Schulten, Klaus

    2002-04-01

    Aquaporins are transmembrane channels found in cell membranes of all life forms. We examine their apparently paradoxical property, facilitation of efficient permeation of water while excluding protons, which is of critical importance to preserving the electrochemical potential across the cell membrane. We have determined the structure of the Escherichia coli aquaglyceroporin GlpF with bound water, in native (2.7 angstroms) and in W48F/F200T mutant (2.1 angstroms) forms, and carried out 12-nanosecond molecular dynamics simulations that define the spatial and temporal probability distribution and orientation of a single file of seven to nine water molecules inside the channel. Two conserved asparagines force a central water molecule to serve strictly as a hydrogen bond donor to its neighboring water molecules. Assisted by the electrostatic potential generated by two half-membrane spanning loops, this dictates opposite orientations of water molecules in the two halves of the channel, and thus prevents the formation of a ``proton wire,'' while permitting rapid water diffusion. Both simulations and observations revealed a more regular distribution of channel water and an increased water permeability for the W48F/F200T mutant.

  5. BLIND CHANNEL ESTIMATION IN DELAY DIVERSITY FOR FREQUENCY SELECTIVE CHANNELS

    Institute of Scientific and Technical Information of China (English)

    Zhao Zheng; Jia Ying; Yin Qinye

    2003-01-01

    Delay diversity is an effective transmit diversity technique to combat adverse ef-fects of fading. Thus far, previous work in delay diversity assumed that perfect estimates ofcurrent channel fading conditions are available at the receiver and training symbols are requiredto estimate the channel from the transmitter to the receiver. However, increasing the number ofthe antennas increases the required training interval and reduces the available time within whichdata may be transmitted. Learning the channel coefficients becomes increasingly difficult for thefrequency selective channels. In this paper, with the subspace method and the delay character ofdelay diversity, a channel estimation method is proposed, which does not use training symbols. Itaddresses the transmit diversity for a frequency selective channel from a single carrier perspectivein the form of a simple equivalent fiat fading model. Monte Carlo simulations give the perfor-mance of channel estimation and the performance comparison of our channel-estimation-baseddetector with decision feedback equalization, which uses the perfect channel information.

  6. Control of the Aquaporin-4 Channel Water Permeability by Structural Dynamics of Aromatic/Arginine Selectivity Filter Residues.

    Science.gov (United States)

    Kitchen, Philip; Conner, Alex C

    2015-11-17

    The aquaporins (AQPs) make up a family of integral membrane proteins that control cellular water flow. Gating of the water channel by conformational changes induced by phosphorylation or protein-protein interactions is an established regulatory mechanism for AQPs. Recent in silico and crystallographic analyses of the structural biology of AQPs suggest that the rate of water flow can also be controlled by small movements of single-amino acid side chains lining the water pore. Here we use measurements of the membrane water permeability of mammalian cells expressing AQP4 mutants to provide the first in vitro evidence in support of this hypothesis. PMID:26512424

  7. Channel selection for automatic seizure detection

    DEFF Research Database (Denmark)

    Duun-Henriksen, Jonas; Kjaer, Troels Wesenberg; Madsen, Rasmus Elsborg; Remvig, Line Sofie; Thomsen, Carsten Eckhart; Sørensen, Helge Bjarup Dissing

    2012-01-01

    Objective: To investigate the performance of epileptic seizure detection using only a few of the recorded EEG channels and the ability of software to select these channels compared with a neurophysiologist. Methods: Fifty-nine seizures and 1419 h of interictal EEG are used for training and testing...... of an automatic channel selection method. The characteristics of the seizures are extracted by the use of a wavelet analysis and classified by a support vector machine. The best channel selection method is based upon maximum variance during the seizure. Results: Using only three channels, a seizure...... recorded directly on the epileptic focus. Conclusions: Based on our dataset, automatic seizure detection can be done using only three EEG channels without loss of performance. These channels should be selected based on maximum variance and not, as often done, using the focal channels. Significance: With...

  8. Molecular determinants of anion selectivity in the cystic fibrosis transmembrane conductance regulator chloride channel pore.

    OpenAIRE

    Linsdell, P; Evagelidis, A; Hanrahan, J W

    2000-01-01

    Ionic selectivity in many cation channels is achieved over a short region of the pore known as the selectivity filter, the molecular determinants of which have been identified in Ca(2+), Na(+), and K(+) channels. However, a filter controlling selectivity among different anions has not previously been identified in any Cl(-) channel. In fact, because Cl(-) channels are only weakly selective among small anions, and because their selectivity has proved so resistant to site-directed mutagenesis, ...

  9. Channel selective tunnelling through a nanographene assembly.

    Science.gov (United States)

    Wong, H S; Feng, X; Müllen, K; Chandrasekhar, N; Durkan, C

    2012-03-01

    We report selective tunnelling through a nanographene intermolecular tunnel junction achieved via scanning tunnelling microscope tip functionalization with hexa-peri-hexabenzocoronene (HBC) molecules. This leads to an offset in the alignment between the energy levels of the tip and the molecular assembly, resulting in the imaging of a variety of distinct charge density patterns in the HBC assembly, not attainable using a bare metallic tip. Different tunnelling channels can be selected by the application of an electric field in the tunnelling junction, which changes the condition of the HBC on the tip. Density functional theory-based calculations relate the imaged HBC patterns to the calculated molecular orbitals at certain energy levels. These patterns bear a close resemblance to the π-orbital states of the HBC molecule calculated at the relevant energy levels, mainly below the Fermi energy of HBC. This correlation demonstrates the ability of an HBC functionalized tip as regards accessing an energy range that is restricted to the usual operating bias range around the Fermi energy with a normal metallic tip at room temperature. Apart from relating to molecular orbitals, some patterns could also be described in association with the Clar aromatic sextet formula. Our observations may help pave the way towards the possibility of controlling charge transport between organic interfaces. PMID:22322294

  10. Cognitive FH Channel Selection for Bluetooth Network

    OpenAIRE

    Yi Peng; Qingzhi Du; Long Hua; Yubing Shao

    2013-01-01

    Bluetooth is a short-range wireless technology that operates in the 2.4GHz unlicensed ISM band, so it will inevitably encounter the interference from other wireless systems and other Bluetooth piconets. Because of the flexible, efficient and reliable spectrum access by adapting the radio’s operating characteristics to the real-time conditions of the environment, cognitive radio technology is apply in Bluetooth network. In this paper, a novel cognitive FH channel selection method which is buil...

  11. Frequency selective tunable spin wave channeling in the magnonic network

    Science.gov (United States)

    Sadovnikov, A. V.; Beginin, E. N.; Odincov, S. A.; Sheshukova, S. E.; Sharaevskii, Yu. P.; Stognij, A. I.; Nikitov, S. A.

    2016-04-01

    Using the space-resolved Brillouin light scattering spectroscopy, we study the frequency and wavenumber selective spin-wave channeling. We demonstrate the frequency selective collimation of spin-wave in an array of magnonic waveguides, formed between the adjacent magnonic crystals on the surface of yttrium iron garnet film. We show the control over spin-wave propagation length by the orientation of an in-plane bias magnetic field. Fabricated array of magnonic crystal can be used as a magnonic platform for multidirectional frequency selective signal processing applications in magnonic networks.

  12. Self-organized models of selectivity in calcium channels

    International Nuclear Information System (INIS)

    The role of flexibility in the selectivity of calcium channels is studied using a simple model with two parameters that accounts for the selectivity of calcium (and sodium) channels in many ionic solutions of different compositions and concentrations using two parameters with unchanging values. We compare the distribution of side chains (oxygens) and cations (Na+ and Ca2+) and integrated quantities. We compare the occupancies of cations Ca2+/Na+ and linearized conductance of Na+. The distributions show a strong dependence on the locations of fixed side chains and the flexibility of the side chains. Holding the side chains fixed at certain predetermined locations in the selectivity filter distorts the distribution of Ca2+ and Na+ in the selectivity filter. However, integrated quantities—occupancy and normalized conductance—are much less sensitive. Our results show that some flexibility of side chains is necessary to avoid obstruction of the ionic pathway by oxygen ions in 'unfortunate' fixed positions. When oxygen ions are mobile, they adjust 'automatically' and move 'out of the way', so they can accommodate the permeable cations in the selectivity filter. Structure is the computed consequence of the forces in this model. The structures are self-organized, at their free energy minimum. The relationship of ions and side chains varies with an ionic solution. Monte Carlo simulations are particularly well suited to compute induced-fit, self-organized structures because the simulations yield an ensemble of structures near their free energy minimum. The exact location and mobility of oxygen ions has little effect on the selectivity behavior of calcium channels. Seemingly, nature has chosen a robust mechanism to control selectivity in calcium channels: the first-order determinant of selectivity is the density of charge in the selectivity filter. The density is determined by filter volume along with the charge and excluded volume of

  13. Selection models for information channels : Applications in multichannel digital marketing

    OpenAIRE

    Winberg, Victor; Eckerdal, Nils

    2015-01-01

    In all digital marketing efforts, different information channels must be selected and used to reach customers. In this thesis, data describing the interactions that members of the loyalty program of a Nordic airline company have had with three information channels is used to estimate four selection models. These multinomial logistic regression models have the purpose of selecting which channel(s) best suits a given member. The models are evaluated and the one that best fits the given situatio...

  14. DISTRIBUTION CHANNELS SELECTION USING PCA-DEA APPROACH

    OpenAIRE

    Milan Andrejić; Milorad Kilibarda

    2015-01-01

    Strategic decision making is very important in logistics. One of the most important strategic decisions in logistics is the selection of distribution channels. This paper proposes the efficiency of distribution channels as one of the main selection criteria. The efficiency of distribution channels simultaneously affects logistics costs and customer satisfaction. Based on the main characteristics of the distribution channels, such as delivery time, service level, volume of business, the level ...

  15. Ion Selectivity in Voltage-gated Biological Ion Channels

    OpenAIRE

    Finnerty, J. J.; Peyser, Alexander; Carloni, Paolo

    2014-01-01

    We demonstrate that a combination of calculating the exact electrostatic potential and approximate volume exclusion within the sub-nanometer selectivity filter of a biological ion channel is critical for estimating the selectivity of the ion channel. Biological membranes separate solutions of different ionic composition which can lead to significant transmembrane voltages and chemical potentials. Ion selective biological ion channels are used by nature to manage these potentials. The high cha...

  16. Multiple flow profiles for two-phase flow in single microfluidic channels through site-selective channel coating

    NARCIS (Netherlands)

    Logtenberg, Hella; Lopez-Martinez, Maria J.; Feringa, Ben L.; Browne, Wesley R.; Verpoorte, Elisabeth

    2011-01-01

    An approach to control two-phase flow systems in a poly(dimethylsiloxane) (PDMS) microfluidic device using spatially selective surface modification is demonstrated. Side-by-side flows of ethanol : water solutions containing different polymers are used to selectively modify both sides of a channel by

  17. A review of channel selection algorithms for EEG signal processing

    Science.gov (United States)

    Alotaiby, Turky; El-Samie, Fathi E. Abd; Alshebeili, Saleh A.; Ahmad, Ishtiaq

    2015-12-01

    Digital processing of electroencephalography (EEG) signals has now been popularly used in a wide variety of applications such as seizure detection/prediction, motor imagery classification, mental task classification, emotion classification, sleep state classification, and drug effects diagnosis. With the large number of EEG channels acquired, it has become apparent that efficient channel selection algorithms are needed with varying importance from one application to another. The main purpose of the channel selection process is threefold: (i) to reduce the computational complexity of any processing task performed on EEG signals by selecting the relevant channels and hence extracting the features of major importance, (ii) to reduce the amount of overfitting that may arise due to the utilization of unnecessary channels, for the purpose of improving the performance, and (iii) to reduce the setup time in some applications. Signal processing tools such as time-domain analysis, power spectral estimation, and wavelet transform have been used for feature extraction and hence for channel selection in most of channel selection algorithms. In addition, different evaluation approaches such as filtering, wrapper, embedded, hybrid, and human-based techniques have been widely used for the evaluation of the selected subset of channels. In this paper, we survey the recent developments in the field of EEG channel selection methods along with their applications and classify these methods according to the evaluation approach.

  18. Control power in perfect controlled teleportation via partially entangled channels

    OpenAIRE

    Li, Xi-Han; Ghose, Shohini

    2014-01-01

    We analyze and evaluate perfect controlled teleportation via three-qubit entangled channels from the point of view of the controller. The key idea in controlled teleportation is that the teleportation is performed only with the participation of the controller. We calculate a quantitative measure of the controller's power and establish a lower bound on the control power required for controlled teleportation. We show that the maximally entangled GHZ state is a suitable channel for controlled te...

  19. Microscopic model for selective permeation in ion channels.

    OpenAIRE

    Wu, J.

    1991-01-01

    Ionic permeation in the selectivity filter of ion channels is analyzed by a microscopic model based on molecular kinetic theory. The energy and flux equations are derived by assuming that: (a) the selectivity filter is formed by a symmetrical array of carbonyl groups; (b) ion movement is near the axis of the channel; (c) a fraction of water molecules is separated from the ion while it moves across the selectivity filter; (d) the applied voltage drops linearly across the selectivity filter; (e...

  20. [Model of the selective calcium channel of characean algae].

    Science.gov (United States)

    Lunevskiĭ, V Z; Zherelova, O M; Aleksandrov, A A; Vinokurov, M G; Berestovskiĭ, G N

    1980-01-01

    The present work was intended to further investigate the selective filter of calcium channel on both a cell membrane and reconstructed channels. For the studies on cell membranes, an inhibitor of chloride channels was chosen (ethacrynic acid) to pass currents only through the calcium channels. On both the cells and reconstructed channels, permeability of ions of different crystal radii and valencies was investigated. The obtained results suggest that the channel represents a wide water pore with a diameter larger than 8 A into which ions go together with the nearest water shell. The values of the maximal currents are given by electrostatic interaction of the ions with the anion center of the channel. A phenomenological two-barrier model of the channel is given which describes the movement of all the ions studied. PMID:6251921

  1. The Control of Male Fertility by Spermatozoan Ion Channels

    Science.gov (United States)

    Lishko, Polina V.; Kirichok, Yuriy; Ren, Dejian; Navarro, Betsy; Chung, Jean-Ju

    2014-01-01

    Ion channels control the sperm ability to fertilize the egg by regulating sperm maturation in the female reproductive tract and by triggering key sperm physiological responses required for successful fertilization such as hyperactivated motility, chemotaxis, and the acrosome reaction. CatSper, a pH-regulated, calcium-selective ion channel, and KSper (Slo3) are core regulators of sperm tail calcium entry and sperm hyperactivated motility. Many other channels had been proposed as regulating sperm activity without direct measurements. With the development of the sperm patch-clamp technique, CatSper and KSper have been confirmed as the primary spermatozoan ion channels. In addition, the voltage-gated proton channel Hv1 has been identified in human sperm tail, and the P2X2 ion channel has been identified in the midpiece of mouse sperm. Mutations and deletions in sperm-specific ion channels affect male fertility in both mice and humans without affecting other physiological functions. The uniqueness of sperm ion channels makes them ideal pharmaceutical targets for contraception. In this review we discuss how ion channels regulate sperm physiology. PMID:22017176

  2. Optimal Channel Allocation with Dynamic Power Control in Cellular Networks

    Directory of Open Access Journals (Sweden)

    Xin Wu

    2011-03-01

    Full Text Available Techniques for channel allocation in cellular networks have been an area of intense research interest formany years. An efficient channel allocation scheme can significantly reduce call-blocking and calldroppingprobabilities. Another important issue is to effectively manage the power requirements forcommunication. An efficient power control strategy leads to reduced power consumption and improvedsignal quality. In this paper, we present a novel integer linear program (ILP formulation that jointlyoptimizes channel allocation and power control for incoming calls, based on the carrier-to-interferenceratio (CIR. In our approach we use a hybrid channel assignment scheme, where an incoming call isadmitted only if a suitable channel is found such that the CIR of all ongoing calls on that channel, as wellas that of the new call, will be above a specified value. Our formulation also guarantees that the overallpower requirement for the selected channel will be minimized as much as possible and that no ongoingcalls will be dropped as a result of admitting the new call. We have run simulations on a benchmark 49cell environment with 70 channels to investigate the effect of different parameters such as the desiredCIR. The results indicate that our approach leads to significant improvements over existing techniques.

  3. DISTRIBUTION CHANNELS SELECTION USING PCA-DEA APPROACH

    Directory of Open Access Journals (Sweden)

    Milan Andrejić

    2015-03-01

    Full Text Available Strategic decision making is very important in logistics. One of the most important strategic decisions in logistics is the selection of distribution channels. This paper proposes the efficiency of distribution channels as one of the main selection criteria. The efficiency of distribution channels simultaneously affects logistics costs and customer satisfaction. Based on the main characteristics of the distribution channels, such as delivery time, service level, volume of business, the level of errors and the different cost categories in this paper the PCA-DEA approach for measuring the efficiency and selection of certain types of distribution channels is proposed. Model is tested on the numerical example. Results show the great capability of the proposed model.

  4. Opportunistic relaying in multipath and slow fading channel: Relay selection and optimal relay selection period

    KAUST Repository

    Sungjoon Park,

    2011-11-01

    In this paper we present opportunistic relay communication strategies of decode and forward relaying. The channel that we are considering includes pathloss, shadowing, and fast fading effects. We find a simple outage probability formula for opportunistic relaying in the channel, and validate the results by comparing it with the exact outage probability. Also, we suggest a new relay selection algorithm that incorporates shadowing. We consider a protocol of broadcasting the channel gain of the previously selected relay. This saves resources in slow fading channel by reducing collisions in relay selection. We further investigate the optimal relay selection period to maximize the throughput while avoiding selection overhead. © 2011 IEEE.

  5. Control microprocessor system for charge particle channeling

    International Nuclear Information System (INIS)

    Control microprocessor systems are widely applied not only in designing industrial robots but in providing functioning of different experimental plants. The experiment control system for charge particle channeling has been considered in the paper. Flexibility, relatively low cost and high reliability are advantages of these systems

  6. Monte Carlo study of gating and selection in potassium channels

    OpenAIRE

    Andreucci, D.; Bellaveglia, D.; Cirillo, E. N. M.; S. Marconi

    2011-01-01

    The study of selection and gating in potassium channels is a very important issue in modern biology. Indeed such structures are known in all types of cells in all organisms where they play many important functional roles. The mechanism of gating and selection of ionic species is not clearly understood. In this paper we study a model in which gating is obtained via an affinity-switching selectivity filter. We discuss the dependence of selectivity and efficiency on the cytosolic ionic concentra...

  7. A Framework for Selection of Intermediary in Marketing Channel

    Directory of Open Access Journals (Sweden)

    Hamid Reza Irani

    2011-10-01

    Full Text Available Purpose – This study seeks to examine how company can select the best intermediary for its Marketing channels with minimum of criteria and time. Design/methodology/approach – A theoretical framework is proposed based on the most
    importance tasks of intermediary and criteria for measuring them. There are four basic tasks and 30 criteria in three independent levels. Subsequently, an exploratory case study in Iranian Food industry is described that illustrates the value of the framework. Findings – It is possible, for example, to apply the theoretical framework to select the intermediary for any industry or any country. Research limitations/implications – The study has possible location- and industry-specific limitations.
    Originality/value – Moreover, the framework has proven to be useful in improving the selection of the intermediary in marketing channel. This is a notable and promising side-effect of the exploratory study, at least from a managerial point of view.
    Keywords: Marketing channel, Distribution channel, Channel design, Selection criteria, channel members, Intermediary selection

  8. OPRA capacity bounds for selection diversity over generalized fading channels

    KAUST Repository

    Hanif, Muhammad Fainan

    2014-05-01

    Channel side information at the transmitter can increase the average capacity by enabling optimal power and rate adaptation. The resulting optimal power and rate adaptation (OPRA) capacity rarely has a closed-form analytic expression. In this paper, lower and upper bounds on OPRA capacity for selection diversity scheme are presented. These bounds hold for variety of fading channels including log-normal and generalized Gamma distributed models and have very simple analytic expressions for easy evaluation even for kth best path selection. Some selected numerical results show that the newly proposed bounds closely approximate the actual OPRA capacity. © 2014 IEEE.

  9. Sub-micron resolution selected area electron channeling patterns

    International Nuclear Information System (INIS)

    Collection of selected area channeling patterns (SACPs) on a high resolution FEG-SEM is essential to carry out quantitative electron channeling contrast imaging (ECCI) studies, as it facilitates accurate determination of the crystal plane normal with respect to the incident beam direction and thus allows control the electron channeling conditions. Unfortunately commercial SACP modes developed in the past were limited in spatial resolution and are often no longer offered. In this contribution we present a novel approach for collecting high resolution SACPs (HR-SACPs) developed on a Gemini column. This HR-SACP technique combines the first demonstrated sub-micron spatial resolution with high angular accuracy of about 0.1°, at a convenient working distance of 10 mm. This innovative approach integrates the use of aperture alignment coils to rock the beam with a digitally calibrated beam shift procedure to ensure the rocking beam is maintained on a point of interest. Moreover a new methodology to accurately measure SACP spatial resolution is proposed. While column considerations limit the rocking angle to 4°, this range is adequate to index the HR-SACP in conjunction with the pattern simulated from the approximate orientation deduced by EBSD. This new technique facilitates Accurate ECCI (A-ECCI) studies from very fine grained and/or highly strained materials. It offers also new insights for developing HR-SACP modes on new generation high-resolution electron columns. - Highlights: • A novel approach is used for rocking beam on new generation FESEM electron columns. • High Resolution SACP collection is developed to carry out quantitative ECCI. • The 4° rocking angle is enough to index the SACP using a simulated pattern. • A new methodology is presented to measure the SACP spatial resolution. • 500 nm spatial resolution at 10 mm working distance was shown for the HR-SACPs

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

    International Nuclear Information System (INIS)

    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)

  11. Statistical Theory of Selectivity and Conductivity in Biological Channels

    CERN Document Server

    Luchinsky, D G; Kaufman, I; Timucin, D A; Eisenberg, R S; McClintock, P V E

    2016-01-01

    We present an equilibrium statistical-mechanical theory of selectivity in biological ion channels. In doing so, we introduce a grand canonical ensemble for ions in a channel's selectivity filter coupled to internal and external bath solutions for a mixture of ions at arbitrary concentrations, we use linear response theory to find the current through the filter for small gradients of electrochemical potential, and we show that the conductivity of the filter is given by the generalized Einstein relation. We apply the theory to the permeation of ions through the potassium selectivity filter, and are thereby able to resolve the long-standing paradox of why the high selectivity of the filter brings no associated delay in permeation. We show that the Eisenman selectivity relation follows directly from the condition of diffusion-limited conductivity through the filter. We also discuss the effect of wall fluctuations on the filter conductivity.

  12. Quantum Model for the Selectivity Filter in K$^{+}$ Ion Channel

    CERN Document Server

    Cifuentes, A A

    2013-01-01

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions thorough the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field which changes the free energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K$^+$ ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone and this increases noise. Moreover, we also show that, for a wide range of driving frequencie...

  13. Modulation of mechanosensitive calcium-selective cation channels by temperature

    Science.gov (United States)

    Ding, J. P.; Pickard, B. G.

    1993-01-01

    Gating of associations of mechanosensitive Ca(2+)-selective cation co-channels in the plasmalemma of onion epidermis has a strong and unusual temperature dependence. Tension-dependent activity rises steeply as temperature is lowered from 25 degrees C to about 6 degrees C, but drops to a low level at about 5 degrees C. Under the conditions tested (with Mg2+ and K+ at the cytosolic face of outside-out membrane patches), promotion results both from more bursting at all observed linkage levels and from longer duration of bursts of co-channels linked as quadruplets and quintuplets. Co-channel conductance decreases linearly, but only modestly, with declining temperature. It is proposed that these and related mechanosensitive channels may participate in a variety of responses to temperature, including thermonasty, thermotropism, hydrotropism, and both cold damage and cold acclimation.

  14. Antenna Subset Selection for Cyclic Prefix Assisted MIMO Wireless Communications over Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    T. Kaiser

    2008-04-01

    Full Text Available Antenna (subset selection techniques are feasible to reduce the hardware complexity of multiple-input multiple-output (MIMO systems, while keeping the benefits of higher-order MIMO systems. Many studies of antenna selection schemes are based on frequency-flat channel models, which are inconsistent to broadband MIMO systems employing spatial-multiplexing. In broadband MIMO systems aiming to provide high-data-rate links, the employed signal bandwidth is typically larger than the coherence bandwidth of the channel so that the channel will be of frequency selective nature. Within this contribution we provide an overview on joint transmitter- and receiver-side antenna subset selection methods for frequency selective channels and deploy them in MIMO orthogonal frequency division multiplexing (OFDM systems and MIMO single-carrier (SC systems employing frequency domain equalization (FDE.

  15. Is ion channel selectivity mediated by confined water?

    OpenAIRE

    Prada-Gracia, Diego; Rao, Francesco

    2012-01-01

    Ion channels form pores across the lipid bilayer, selectively allowing inorganic ions to cross the membrane down their electrochemical gradient. While the study of ion desolvation free-energies have attracted much attention, the role of water inside the pore is less clear. Here, molecular dynamics simulations of a reduced model of the KcsA selectivity filter indicate that the equilibrium position of Na+, but not of K+, is strongly influenced by confined water. The latter forms a stable comple...

  16. Threonine in the selectivity filter of the acetylcholine receptor channel.

    OpenAIRE

    Villarroel, A.; Sakmann, B

    1992-01-01

    The acetylcholine receptor (AChR) is a cation selective channel whose biophysical properties as well as its molecular composition are fairly well characterized. Previous studies on the rat muscle alpha-subunit indicate that a threonine residue located near the cytoplasmic side of the M2 segment is a determinant of ion flow. We have studied the role of this threonine in ionic selectivity by measuring conductance sequences for monovalent alkali cations and bionic reversal potentials of the wild...

  17. Ionic Selectivity and Permeation Properties of Human PIEZO1 Channels.

    Directory of Open Access Journals (Sweden)

    Radhakrishnan Gnanasambandam

    Full Text Available Members of the eukaryotic PIEZO family (the human orthologs are noted hPIEZO1 and hPIEZO2 form cation-selective mechanically-gated channels. We characterized the selectivity of human PIEZO1 (hPIEZO1 for alkali ions: K+, Na+, Cs+ and Li+; organic cations: TMA and TEA, and divalents: Ba2+, Ca2+, Mg2+ and Mn2+. All monovalent ions permeated the channel. At a membrane potential of -100 mV, Cs+, Na+ and K+ had chord conductances in the range of 35-55 pS with the exception of Li+, which had a significantly lower conductance of ~ 23 pS. The divalents decreased the single-channel permeability of K+, presumably because the divalents permeated slowly and occupied the open channel for a significant fraction of the time. In cell-attached mode, 90 mM extracellular divalents had a conductance for inward currents carried by the divalents of: 25 pS for Ba2+ and 15 pS for Ca2+ at -80 mV and 10 pS for Mg2+ at -50 mV. The organic cations, TMA and TEA, permeated slowly and attenuated K+ currents much like the divalents. As expected, the channel K+ conductance increased with K+ concentration saturating at ~ 45 pS and the KD of K+ for the channel was 32 mM. Pure divalent ion currents were of lower amplitude than those with alkali ions and the channel opening rate was lower in the presence of divalents than in the presence of monovalents. Exposing cells to the actin disrupting reagent cytochalasin D increased the frequency of openings in cell-attached patches probably by reducing mechanoprotection.

  18. Joint Relay Selection and Power Allocation for Cooperative Communication over Frequency Selective Fading Channels

    Directory of Open Access Journals (Sweden)

    Youhua Ma

    2012-08-01

    Full Text Available In this paper, we consider the joint problem of relay selection and optimal power allocation for multi-relay amplify-and-forward (AF cooperative communication system over frequency selective fading channels. An optimization model combined relay selection and power allocation under a total transmission power budget is formulated. Then, this combinatorial problem is solved in a distributed strategy. Relay selection with a new threshold-based multiple-relay selection (MRS scheme is implemented at first, and then power is allocated between source and the selected relays in an optimized way to maximize channel capacity. Simulation result shows that the proposed joint scenario with relay selection and power allocation achieves better throughput performance than that of parallel-relay scenario (means that random relay is selected to forward data and allocated part of total power on average. Furthermore, the performances of the new MRS scheme and other relay selection strategies are also investigated.

  19. Develop A Framework for Selection of Intermediary in Marketing Channel

    Directory of Open Access Journals (Sweden)

    Hamid Reza Irani

    2011-03-01

    Full Text Available This study seeks to examine how a company can select the best intermediary for itsMarketing channels with minimum of criteria and time. A theoretical framework is proposed basedon the most important tasks of intermediary and the criteria to measure them. There are four basictasks and thirty criteria in three independent levels. Subsequently, an exploratory case study inIranian Food industry is described to illustrate the value of the framework. It is possible to apply thetheoretical framework to select the intermediary for any industry or country. However, there mightbe possible location-specific or industry-specific limitations. Moreover, the framework has provedto be useful in improving the selection of the intermediary in marketing channel. This is a notableand promising side-effect of the exploratory study, at least from a managerial point of view.

  20. Is ion channel selectivity mediated by confined water?

    CERN Document Server

    Prada-Gracia, Diego

    2012-01-01

    Ion channels form pores across the lipid bilayer, selectively allowing inorganic ions to cross the membrane down their electrochemical gradient. While the study of ion desolvation free-energies have attracted much attention, the role of water inside the pore is less clear. Here, molecular dynamics simulations of a reduced model of the KcsA selectivity filter indicate that the equilibrium position of Na+, but not of K+, is strongly influenced by confined water. The latter forms a stable complex with Na+, moving the equilibrium position of the ion to the plane of the backbone carbonyls. Almost at the centre of the binding site, the water molecule is trapped by favorable electrostatic interactions and backbone hydrogen-bonds. In the absence of confined water the equilibrium position of both Na+ and K+ is identical. Our observations strongly suggest a previously unnoticed active role of confined water in the selectivity mechanism of ion channels.

  1. Protein structure and ionic selectivity in calcium channels: Selectivity filter size, not shape, matters

    OpenAIRE

    Malasics, Attila; Gillespie, Dirk; Nonner, Wolfgang; Henderson, Douglas; Eisenberg, Bob; Boda, Dezső

    2009-01-01

    Calcium channels have highly charged selectivity filters (4 COO− groups) that attract cations in to balance this charge and minimize free energy, forcing the cations (Na+ and Ca2+) to compete for space in the filter. A reduced model was developed to better understand the mechanism of ion selectivity in calcium channels. The charge/space competition (CSC) mechanism implies that Ca2+ is more efficient in balancing the charge of the filter because it provides twice the charge as Na+ while occupy...

  2. A Combined Antenna Arrays and Reverse-Link Synchronous DS-CDMA System over Frequency-Selective Fading Channels with Power Control Error

    Directory of Open Access Journals (Sweden)

    Yong-Seok Kim

    2004-08-01

    Full Text Available An improved antenna array (AA has been introduced, in which reverse-link synchronous transmission technique (RLSTT is incorporated to effectively make better an estimation of covariance matrices at a beamformer-RAKE receiver. While RLSTT is effective in the first finger at the RAKE receiver in order to reject multiple-access interference (MAI, the beamformer estimates the desired user's complex weights, enhancing its signal and reducing cochannel interference (CCI from the other directions. In this work, it is attempted to provide a comprehensive analysis of user capacity which reflects several important factors such as the shape of multipath intensity profile (MIP, the number of antennas, and power control error (PCE. Theoretical analysis, confirmed by the simulations, demonstrates that the orthogonality provided by employing RLSTT along with AA may make the DS-CDMA system insensitive to the PCE even with fewer numbers of antennas.

  3. Discrimination between mountain stream channel types using independent control variables

    Science.gov (United States)

    Wohl, E.; Merritt, D. M.

    2004-12-01

    We use a large and diverse dataset from mountain streams around the world to explore our ability to classify reach-scale channel morphology using easily measurable control variables. The dataset includes 136 step-pool reaches, 44 plane-bed reaches, and 93 pool-riffle reaches from streams in the western United States, Panama, and New Zealand. We used stepwise discriminant analysis to select the most parsimonious subset of variables for classifying channel type. A 3-variable discriminant function using slope, D84, and channel width produced a classification error rate of 24% (103 reaches correctly classified). Seventy percent of plane-bed reaches were correctly classified (16% incorrectly classified as pool-riffle, 14% incorrectly classified as step-pool). Sixty-seven percent of pool-riffle channels were correctly classified (31% incorrectly classified as plane-bed, 2% as step-pool). Eighty-nine percent of step-pool reaches were correctly classified (9% incorrectly classified as plane-bed, 2% as pool-riffle). The partial R2-values indicate that slope is by far the most significant single explanatory variable. The ability to accurately classify channel type in other regions using the elegant 3-variable discriminant function developed from the entire dataset has important implications for water-resources management and for understanding relationships between process and form in mountain streams.

  4. On Channel Estimation for Analog Network Coding in a Frequency-Selective Fading Channel

    Directory of Open Access Journals (Sweden)

    Sjödin Tomas

    2011-01-01

    Full Text Available Recently, broadband analog network coding (ANC was introduced for high-speed transmission over the wireless (frequency-selective fading channel. However, ANC requires the knowledge of channel state information (CSI for self-information removal and coherent signal detection. In ANC, the users' pilot signals interfere during the first slot, which renders the relay unable to estimate CSIs of different users, and, consequently, four time-slot pilot-assisted channel estimation (CE is required to avoid interference. Naturally, this will reduce the capacity of ANC scheme. In this paper, we theoretically analyze the bit error rate (BER performance of bi-directional broadband ANC communication based on orthogonal frequency division multiplexing (OFDM radio access. We also theoretically analyze the performance of the channel estimator's mean square error (MSE. The analysis is based on the assumption of perfect timing and frequency synchronization. The achievable BER performance and the estimator's MSE for broadband ANC is evaluated by numerical and computer simulation. We discuss how, and by how much, the imperfect knowledge of CSI affects the BER performance of broadband ANC. It is shown that the CE scheme achieves a slightly higher BER in comparison with ideal CE case for a low and moderate mobile terminal speed in a frequency-selective fading channel.

  5. Mechanosensory calcium-selective cation channels in epidermal cells

    Science.gov (United States)

    Ding, J. P.; Pickard, B. G.

    1993-01-01

    This paper explores the properties and likely functions of an epidermal Ca(2+)-selective cation channel complex activated by tension. As many as eight or nine linked or linkable equivalent conductance units or co-channels can open together. Open time for co-channel quadruplets and quintuplets tends to be relatively long with millimolar Mg2+ (but not millimolar Ca2+) at the cytosolic face of excised plasma membrane. Sensitivity to tension is regulated by transmembrane voltage and temperature. Under some circumstances channel activity is sychronized in rhythmic pulses. Certain lanthanides and a cytoskeleton-disturbing herbicide that inhibit gravitropic reception act on the channel system at low concentrations. Specifically, ethyl-N-phenylcarbamate promotes tension-dependent activity at micromolar levels. With moderate suction, Gd3+ provided at about 0.5 micromole at the extracellular face of the membrane promotes for several seconds but may then become inhibitory. Provision at 1-2 micromoles promotes and subsequently inhibits more vigorously (often abruptly and totally), and at high levels inhibits immediately. La3+, a poor gravitropic inhibitor, acts similarly but much more gradually and only at much higher concentrations. These properties, particularly these susceptibilities to modulation, indicate that in vivo the mechanosensitive channel must be mechanosensory and mechanoregulatory. It could serve to transduce the shear forces generated in the integrated wall-membrane-cytoskeleton system during turgor changes and cell expansion as well as transducing the stresses induced by gravity, touch and flexure. In so far as such transduction is modulated by voltage and temperature, the channels would also be sensors for these modalities as long as the wall-membrane-cytoskeleton system experiences mechanical stress.

  6. Hopping control channel MAC protocol for opportunistic spectrum access networks

    Institute of Scientific and Technical Information of China (English)

    FU Jing-tuan; JI Hong; MAO Xu

    2010-01-01

    Opportunistic spectrum access (OSA) is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access (CHMA) protocol,we introduce a hopping control channel medium access control (MAC) protocol in the context of OSA networks. In our proposed protocol,all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users' occupancy of the channel,we use a primary user (PU) detection model to calculate the channel availability for unlicensed users' access. Then,a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation,we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.

  7. The new secondary channel control system at TRIUMF

    International Nuclear Information System (INIS)

    The control of the secondary channels at TRIUMF has been decentralized. Each channel is now controlled through a single CAMAC crate from an IBM PC in the experimental counting room. Intelligent motor controllers were developed to replace the ageing slit control system. Advanced features of the control software package TICS, such as computer optimization of channel parameters and high-voltage conditioning of the dc separators, are described. (orig.)

  8. Channel Selection Based on Trust and Multiarmed Bandit in Multiuser, Multichannel Cognitive Radio Networks

    OpenAIRE

    2014-01-01

    This paper proposes a channel selection scheme for the multiuser, multichannel cognitive radio networks. This scheme formulates the channel selection as the multiarmed bandit problem, where cognitive radio users are compared to the players and channels to the arms. By simulation negotiation we can achieve the potential reward on each channel after it is selected for transmission; then the channel with the maximum accumulated rewards is formally chosen. To further improve the performance, the ...

  9. SK channel-selective opening by SKA-31 induces hyperpolarization and decreases contractility in human urinary bladder smooth muscle

    OpenAIRE

    Soder, Rupal P; Parajuli, Shankar P.; Hristov, Kiril L.; Eric S. Rovner; Petkov, Georgi V.

    2012-01-01

    Overactive bladder (OAB) is often associated with increased involuntary detrusor smooth muscle (DSM) contractions during the bladder-filling phase. To develop novel therapies for OAB, it is critical to better understand the mechanisms that control DSM excitability and contractility. Recent studies showed that small-conductance Ca2+-activated K+ (SK) channels, SK3 channels, in particular, regulate human DSM function. However, the concept that SK channel-selective pharmacological activation can...

  10. Channel Selection Based on Trust and Multiarmed Bandit in Multiuser, Multichannel Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Fanzi Zeng

    2014-01-01

    Full Text Available This paper proposes a channel selection scheme for the multiuser, multichannel cognitive radio networks. This scheme formulates the channel selection as the multiarmed bandit problem, where cognitive radio users are compared to the players and channels to the arms. By simulation negotiation we can achieve the potential reward on each channel after it is selected for transmission; then the channel with the maximum accumulated rewards is formally chosen. To further improve the performance, the trust model is proposed and combined with multi-armed bandit to address the channel selection problem. Simulation results validate the proposed scheme.

  11. A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs.

    Science.gov (United States)

    Mo, Yuanfu; Yu, Dexin; Song, Jun; Zheng, Kun; Guo, Yajuan

    2015-01-01

    In a vehicular ad hoc network (VANET), the periodic exchange of single-hop status information broadcasts (beacon frames) produces channel loading, which causes channel congestion and induces information conflict problems. To guarantee fairness in beacon transmissions from each node and maximum network connectivity, adjustment of the beacon transmission power is an effective method for reducing and preventing channel congestion. In this study, the primary factors that influence wireless channel loading are selected to construct the KF-BCLF, which is a channel load forecasting algorithm based on a recursive Kalman filter and employs multiple regression equation. By pre-adjusting the transmission power based on the forecasted channel load, the channel load was kept within a predefined range; therefore, channel congestion was prevented. Based on this method, the CLF-BTPC, which is a transmission power control algorithm, is proposed. To verify KF-BCLF algorithm, a traffic survey method that involved the collection of floating car data along a major traffic road in Changchun City is employed. By comparing this forecast with the measured channel loads, the proposed KF-BCLF algorithm was proven to be effective. In addition, the CLF-BTPC algorithm is verified by simulating a section of eight-lane highway and a signal-controlled urban intersection. The results of the two verification process indicate that this distributed CLF-BTPC algorithm can effectively control channel load, prevent channel congestion, and enhance the stability and robustness of wireless beacon transmission in a vehicular network. PMID:26571042

  12. Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels

    OpenAIRE

    Boda, D.; Leaf, G.; Fonseca, J.; Eisenberg, B.

    2015-01-01

    The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity filter of the channel is used. The selectivity filter of this channel type contains aspartate (D), glutamate (E), lysine (K), and alanine (A) residues (the DEKA locus). We use Grand Canonical Monte Carlo simulations to compute equilibrium binding selectivity in the selectivity filter and to obtain various terms of the excess chemical potential from a particle insertio...

  13. Cyclostationary signature design for common control channel of cognitive radio

    Institute of Scientific and Technical Information of China (English)

    QI Yuan; PENG Tao; WANG Wen-bo; LUO Shi-feng

    2009-01-01

    Embedding specific signatures in transmitted signals for identifying common control channels of cognitive radio are addressed in research laboratories because availability of the spectrum occupied by the common control channel might change in time. A novel solution to embed a unique cyclostationary signature for the common control channel of cognitive radio is proposed in this article. Based on linear periodically time-variant transformation (LPTV) model, the cyclic autocorrelation expression of the proposed signature is derived, which characterizes its cyclostationarity. Analysis of the cyclostationary signature is presented considering effects of additive white Gaussian noise(AWGN)and multiplath channels. Simulation results illustrating the reliability of signatures are given.

  14. K+ and Na+ Conduction in Selective and Nonselective Ion Channels Via Molecular Dynamics Simulations

    OpenAIRE

    Furini, Simone; Domene, Carmen

    2013-01-01

    Generations of scientists have been captivated by ion channels and how they control the workings of the cell by admitting ions from one side of the cell membrane to the other. Elucidating the molecular determinants of ion conduction and selectivity are two of the most fundamental issues in the field of biophysics. Combined with ongoing progress in structural studies, modeling and simulation have been an integral part of the development of the field. As of this writing, the relentless growth i...

  15. Software of microprogrammed controller of ES computer channel

    International Nuclear Information System (INIS)

    Instruction set of the microprogrammed controller of the Es computer channel is described. These provide some internal and external operations and data transfer between the ES computer memory and MCC registers under the control of the channel program. The variants of ending abonent instructions are given

  16. Game Theoretical Approaches for Transport-Aware Channel Selection in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Chen Shih-Ho

    2010-01-01

    Full Text Available Effectively sharing channels among secondary users (SUs is one of the greatest challenges in cognitive radio network (CRN. In the past, many studies have proposed channel selection schemes at the physical or the MAC layer that allow SUs swiftly respond to the spectrum states. However, they may not lead to enhance performance due to slow response of the transport layer flow control mechanism. This paper presents a cross-layer design framework called Transport Aware Channel Selection (TACS scheme to optimize the transport throughput based on states, such as RTT and congestion window size, of TCP flow control mechanism. We formulate the TACS problem as two different game theoretic approaches: Selfish Spectrum Sharing Game (SSSG and Cooperative Spectrum Sharing Game (CSSG and present novel distributed heuristic algorithms to optimize TCP throughput. Computer simulations show that SSSG and CSSG could double the SUs throughput of current MAC-based scheme when primary users (PUs use their channel infrequently, and with up to 12% to 100% throughput increase when PUs are more active. The simulation results also illustrated that CSSG performs up to 20% better than SSSG in terms of the throughput.

  17. On channel selection and shape co-existence

    International Nuclear Information System (INIS)

    Ambivalence with respect to a favoured shape is emerging as a ubiquitous phenomenon in nuclei. Multiple minima in the nuclear potential well occur because of the delicate balance in nuclei between the long and short-range properties of the nuclear force and the contribution specific particle orbitals make in forcing the nucleus to a decision. Exploration of the dependence of the resulting shape co-existence on particle number and orbital is a prominent area of research. Experimental aspects of spectroscopy studies using heavy ion fusion, evaporation reactions and channel selection are discussed, with focus on shape co-existence in the light Os-Pt-Hg-Pb region. 42 refs., 8 figs

  18. Cognitive Radio Channel Selection Strategy Based on Experience-Weighted Attraction Learning

    OpenAIRE

    Qian Jiansheng; Sun Yong

    2013-01-01

    In this paper, an innovative proposed channel selection algorithm based on Experience-Weighted Attraction (EWA) learning allows Cognitive Radio (CR) to learn radio environment communication channel characteristics online. By accumulating the history channel experience, it can predict, select and change the current optimal communication channel, dynamic ensure the quality of communication links and finally reduce system communication outage probability. Validation and reliability have been str...

  19. 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.

  20. Controlled beta-quenching of fuel channels using inert gas

    International Nuclear Information System (INIS)

    The trend towards higher fuel assembly discharge burnups poses new challenges for fuel channels in terms of their dimensional behavior and corrosion resistance. This led AREVA NP to develop a new technique for beta quenching of fuel channels that combines the effect of beta-quenching with the optimization of the microstructure. The first set of fuel channels with these optimized material properties have been placed in the core of a German boiling water reactor (BWR) nuclear power plant in spring of 2004. Some more channels have been sited in the core of a Scandinavian BWR in fall of 2007 to broaden the in-pile experience with these channels. Dimensional stability is the major requirement that is applied to fuel channels. High corrosion resistance and low hydrogen pickup are certainly required as well. However, corrosion and hydrogen pickup are usually not life limiting factors due to the large wall thickness of the material. Since thick layers of oxide may spall off extensively at high burnup and cause increase of the dose rate for the personnel, high corrosion resistance of fuel channels is mandatory. The fuel channels which surround BWR fuel assemblies are exposed to neutron irradiation as well as to loads induced by the reactor coolant flowing through them. These service conditions induce material growth and creep which cause permanent changes in the dimensions of the channels. Especially, fuel channel bow is of certain interest as increased channel bow may lead to some friction with control blades. Fuel channel bow is mainly induced by fluence gradients. However, there may be additional influences such as oxidation and hydrogen uptake to cause increased channel bow. The effect of hydrogen is currently discussed in the nuclear community to explain the unexpected high fuel channel bow that has been observed in some nuclear power plants. (orig.)

  1. Current and selectivity in a model sodium channel under physiological conditions: Dynamic Monte Carlo simulations

    OpenAIRE

    Csányi, Éva; Boda, Dezső; Gillespie, Dirk; Kristóf, Tamás

    2011-01-01

    A reduced model of a sodium channel is analyzed using Dynamic Monte Carlo simulations. These include the first simulations of ionic current under approximately physiological ionic conditions through a model sodium channel and an analysis of how mutations of the sodium channel’s DEKA selectivity filter motif transform the channel from being Na+ selective to being Ca2+ selective. Even though the model of the pore, amino acids, and permeant ions is simplified, the model reproduces the fundamenta...

  2. Deterministic controlled remote state preparation using partially entangled quantum channel

    Science.gov (United States)

    Chen, Na; Quan, Dong Xiao; Yang, Hong; Pei, Chang Xing

    2016-04-01

    In this paper, we propose a novel scheme for deterministic controlled remote state preparation (CRSP) of arbitrary two-qubit states. Suitably chosen partially entangled state is used as the quantum channel. With proper projective measurements carried out by the sender and controller, the receiver can reconstruct the target state by means of appropriate unitary operation. Unit success probability can be achieved for arbitrary two-qubit states. Different from some previous CRSP schemes utilizing partially entangled channels, auxiliary qubit is not required in our scheme. We also show that the success probability is independent of the parameters of the partially entangled quantum channel.

  3. Electrostatic tuning of permeation and selectivity in aquaporin water channels

    DEFF Research Database (Denmark)

    Jensen, Mogens O Stibius; Tajkhorshid, E.; Schulten, K.

    2003-01-01

    stronger than water-protein interactions, except near a conserved, positively charged Arg residue. We find that variations of the protein electrostatic field through the channel, owing to preserved structural features, completely explain the bipolar orientation of water. This orientation persists despite......Water permeation and electrostatic interactions between water and channel are investigated in the Escherichia coli glycerol uptake facilitator GlpF, a member of the aquaporin water channel family, by molecular dynamics simulations. A tetrameric model of the channel embedded in a 16:0/ 18:1c9......-palmitoyloleylphosphatidylethanolamine membrane was used for the simulations. During the simulations, water molecules pass through the channel in single file. The movement of the single. le water molecules through the channel is concerted, and we show that it can be described by a continuous-time random-walk model. The integrity of the...

  4. Critical assessment of OmpF channel selectivity: merging information from different experimental protocols

    International Nuclear Information System (INIS)

    The ion selectivity of a channel can be quantified in several ways by using different experimental protocols. A wide, mesoscopic channel, the OmpF porin of the outer membrane of E. coli, serves as a case study for comparing and analysing several measures of the channel cation-anion permeability in chlorides of alkali metals (LiCl, NaCl, KCl, CsCl). We show how different insights can be gained and integrated to rationalize the global image of channel selectivity. To this end, reversal potential, channel conductance and bi-ionic potential (two different salts with a common anion on each side of the channel but with the same concentration) experiments are discussed in light of an electrodiffusion model based on the Poisson-Nernst-Planck formalism. Measurements and calculations based on the atomic crystal structure of the channel show that each protocol displays a particular balance between the different sources of selectivity.

  5. Tuning the ion selectivity of tetrameric cation channels by changing the number of ion binding sites

    Energy Technology Data Exchange (ETDEWEB)

    Derebe, Mehabaw G.; Sauer, David B.; Zeng, Weizhong; Alam, Amer; Shi, Ning; Jiang, Youxing (UTSMC); (ETH Zurich)

    2015-11-30

    Selective ion conduction across ion channel pores is central to cellular physiology. To understand the underlying principles of ion selectivity in tetrameric cation channels, we engineered a set of cation channel pores based on the nonselective NaK channel and determined their structures to high resolution. These structures showcase an ensemble of selectivity filters with a various number of contiguous ion binding sites ranging from 2 to 4, with each individual site maintaining a geometry and ligand environment virtually identical to that of equivalent sites in K{sup +} channel selectivity filters. Combined with single channel electrophysiology, we show that only the channel with four ion binding sites is K{sup +} selective, whereas those with two or three are nonselective and permeate Na{sup +} and K{sup +} equally well. These observations strongly suggest that the number of contiguous ion binding sites in a single file is the key determinant of the channel's selectivity properties and the presence of four sites in K{sup +} channels is essential for highly selective and efficient permeation of K{sup +} ions.

  6. Valence selectivity of the gramicidin channel: a molecular dynamics free energy perturbation study.

    OpenAIRE

    Roux, B

    1996-01-01

    The valence selectivity of the gramicidin channel is examined using computer simulations based on atomic models. The channel interior is modeled using a gramicidin-like periodic poly (L,D)-alanine beta-helix. Free energy perturbation calculations are performed to obtain the relative affinity of K+ and Cl- for the channel. It is observed that the interior of the gramicidin channel provides an energetically favorable interaction site for a cation but not for an anion. Relative to solvation in b...

  7. How to Achieve the Optimal DMT of Selective Fading MIMO Channels?

    OpenAIRE

    Mroueh, Lina; Belfiore, Jean-Claude

    2010-01-01

    In this paper, we consider a particular class of selective fading channel corresponding to a channel that is selective either in time or in frequency. For this class of channel, we propose a systematic way to achieve the optimal DMT derived in Coronel and B\\"olcskei, IEEE ISIT, 2007 by extending the non-vanishing determinant (NVD) criterion to the selective channel case. A new code construction based on split NVD parallel codes is then proposed to satisfy the NVD parallel criterion. This resu...

  8. Non-equilibrium dynamics contribute to ion selectivity in the KcsA channel.

    Directory of Open Access Journals (Sweden)

    Van Ngo

    Full Text Available The ability of biological ion channels to conduct selected ions across cell membranes is critical for the survival of both animal and bacterial cells. Numerous investigations of ion selectivity have been conducted over more than 50 years, yet the mechanisms whereby the channels select certain ions and reject others are not well understood. Here we report a new application of Jarzynski's Equality to investigate the mechanism of ion selectivity using non-equilibrium molecular dynamics simulations of Na(+ and K(+ ions moving through the KcsA channel. The simulations show that the selectivity filter of KcsA adapts and responds to the presence of the ions with structural rearrangements that are different for Na(+ and K(+. These structural rearrangements facilitate entry of K(+ ions into the selectivity filter and permeation through the channel, and rejection of Na(+ ions. A mechanistic model of ion selectivity by this channel based on the results of the simulations relates the structural rearrangement of the selectivity filter to the differential dehydration of ions and multiple-ion occupancy and describes a mechanism to efficiently select and conduct K(+. Estimates of the K(+/Na(+ selectivity ratio and steady state ion conductance for KcsA from the simulations are in good quantitative agreement with experimental measurements. This model also accurately describes experimental observations of channel block by cytoplasmic Na(+ ions, the "punch through" relief of channel block by cytoplasmic positive voltages, and is consistent with the knock-on mechanism of ion permeation.

  9. Coulomb blockade model of permeation and selectivity in biological ion channels

    OpenAIRE

    Kaufman, Igor Kh.; McClintock, Peter V. E.; Eisenberg, R S

    2015-01-01

    Biological ion channels are protein nanotubes embedded in, and passing through, the bilipid membranes of cells. Physiologically, they are of crucial importance in that they allow ions to pass into and out of cells, fast and efficiently, though in a highly selective way. Here we show that the conduction and selectivity of calcium/sodium ion channels can be described in terms of ionic Coulomb blockade in a simplified electrostatic and Brownian dynamics model of the channel. The Coulomb blockade...

  10. Study of Selectivity and Permeation In Voltage-Gated Ion Channels

    OpenAIRE

    Giri, Janhavi

    2012-01-01

    Ion channels are membrane proteins responsible for an enormous range of biological functions. Ion selectivity and permeation are based on simple laws of physics and chemistry. Ion channels are therefore ideal candidates for physical investigation. A reduced model generates the selectivity of voltage-gated L-type calcium channel under a wide range of ionic conditions using only two parameters with unchanging values. The reasons behind the success of this reduced model are investigated. Monte C...

  11. Use of depleted fuel as a mitigation method for reducing FAC in selected channels

    International Nuclear Information System (INIS)

    Feeder pipes located at the outlet of fuel channels are known to corrode at a higher rate than expected. The degradation mechanism is identified as flow-assisted corrosion (FAC) and seems to affect all CANDU plants. The extent of feeder thinning was discovered in 1995 after the mechanical cleaning of steam generators. The transport mechanism of magnetite is dissolution of irons at the outlet feeder and deposition on the cold leg of steam generator tubes. Multiple factors affect the thinning rates and pH is one that was quickly readjusted in order to minimize iron solubility. Feeder inspection started rapidly at Gentilly-2 and thickness measurements were performed at every outage since 1996. Data collected over the years showed a certain pattern of thinning of the feeders most affected by FAC. The feeders that would need early dispositions are 2-inch size pipes with a compound bend (730 and 700). A closer look at this feeder outlet geometry showed some correlation between thinning rate and boiling rate. One observed tendency is a reduction of thinning rate following the cleaning of steam generators in 1999 - thus linking boiling to thinning rate. Although the possible correlation between boiling and thinning rate is based on a limited amount of data, Gentilly-2 decided to conduct an experiment to see if reducing boiling in selected channels may slow down the thinning rate. The experiment consisted of cuffing boiling by using a number of depleted fuel bundles in specific channels to maintain the outlet temperature below saturation temperature. Two channels were refueled with depleted fuel in Nov. and Dec. 2000. Close monitoring of these two channels (D5 and C6) and their twin (symmetric) channels (C17 and D18) would permit a conclusion regarding the effectiveness of controlling the power of selected channels for minimizing the thinning rate. Results obtained in 2002 show promising results but a longer assessment period is required to eliminate any doubt. Longer term

  12. Selection of marketing channels for the distribution of industrial enterprises’ innovative products

    Directory of Open Access Journals (Sweden)

    L.O. Syhyda

    2014-03-01

    Full Text Available The aim of the article. The aim of the study is to determine the stages by which it is possible to select among existing marketing channels of the enterprise ones that would be best to use in innovative products’ distribution. The results of the analysis. The author proposes stages by following which it is possible to choose marketing channels for the innovative products’ distribution at industrial enterprises. At the first stage of marketing channels’ selection diagnostics of marketing distribution policy actual state is held. It allows to identify shortcomings in the distribution system and to identify areas of its improvement in order to bring the finished products to customers in the best conditions. At the second stage the assessment of enterprise’s existing marketing channels is provided. The assessment helps to define marketing channels of the enterprise and the type of innovative products that can be distributed via them. The third stage provides the selection of the most relevant marketing channels among existing channels at the enterprise. Those channels are expected to spread innovative products. The selection is based on qualitative assessment. A qualitative assessment of the marketing channel of innovative products is made by following criterias: - target market of innovative product and market on which channel operates; - compliance of innovative product to the range of products which are distributed via the channel; - actions for advance of an innovative product; - willingness of participants in channel to distribute innovative product; - level of expenses for distribution of innovative product via the channel; - risk at distribution of innovative products in the channel. The last, fourth stage involves selection of management strategies for marketing channels of innovative product. Conclusions and directions of further researches. Thus, the proposed sequence of stages of innovative products’ marketing channels choice

  13. Channel and delay estimation for base-station–based cooperative communications in frequency-selective fading channels

    Directory of Open Access Journals (Sweden)

    Hongjun Xu

    2011-07-01

    Full Text Available A channel and delay estimation algorithm for both positive and negative delay, based on the distributed Alamouti scheme, has been recently discussed for base-station–based asynchronous cooperative systems in frequency-flat fading channels. This paper extends the algorithm, the maximum likelihood estimator, to work in frequency-selective fading channels. The minimum mean square error (MMSE performance of channel estimation for both packet schemes and normal schemes is discussed in this paper. The symbol error rate (SER performance of equalisation and detection for both time-reversal space-time block code (STBC and single-carrier STBC is also discussed in this paper. The MMSE simulation results demonstrated the superior performance of the packet scheme over the normal scheme with an improvement in performance of up to 6 dB when feedback was used in the frequency-selective channel at a MSE of 3 x 10–2. The SER simulation results showed that, although both the normal and packet schemes achieved similar diversity orders, the packet scheme demonstrated a 1 dB coding gain over the normal scheme at a SER of 10–5. Finally, the SER simulations showed that the frequency-selective fading system outperformed the frequency-flat fading system.

  14. How to Achieve the Optimal DMT of Selective Fading MIMO Channels?

    CERN Document Server

    Mroueh, Lina

    2010-01-01

    In this paper, we consider a particular class of selective fading channel corresponding to a channel that is selective either in time or in frequency. For this class of channel, we propose a systematic way to achieve the optimal DMT derived in Coronel and B\\"olcskei, IEEE ISIT, 2007 by extending the non-vanishing determinant (NVD) criterion to the selective channel case. A new code construction based on split NVD parallel codes is then proposed to satisfy the NVD parallel criterion. This result is of significant interest not only in its own right, but also because it settles a long-standing debate in the literature related to the optimal DMT of selective fading channels.

  15. Insights About Channel Width Controls Based on Channel Narrowing Below Dams

    Science.gov (United States)

    Schmidt, J. C.

    2007-12-01

    All channels narrow under conditions of flood reduction, such as downstream from dams, but the magnitude of narrowing is highly variable. Channel width changes on 61 dam-impacted reaches covering more than 4000 km of six large rivers of the western United States (Missouri, Rio Grande, Colorado, Trinity, Snake, Deschutes) were reviewed in an extensive literature search, supplemented by field studies on the Rio Grande, Colorado River and its tributaries, and Snake River. These studies demonstrate that narrowing occurs under conditions of post-dam sediment deficit and surplus, indicating that the primary control on width is not sediment mass balance. However, channel width changes are not related to flood reduction in a simple way, such as would be predicted by downstream hydraulic geometry relations. Narrowing is of larger magnitude on rivers with large suspended sediment loads, and is less obvious on gravel-bed rivers in sediment surplus. Narrowing occurs where beds incise and where this is not the case. Narrowing occurs in the presence or absence of invasive, woody riparian vegetation. Large-scale channel organization, such as distinguishing between meandering and debris-fan affected channels, has a strong effect on the magnitude of narrowing, primarily because the mechanism of narrowing differs between these major channel types. We examined channels whose post-dam 2-yr flood is as little as 0.20 times the pre-dam flood and where channel width narrowed by as much as 0.15 times of the pre- dam width. Field studies were based on extensive analysis of historical data as well an dendrogeomorphic interpretation of floodplain sediments.

  16. CYCLOSTATIONARITY-BASED OFDM SIGNAL SENSING OVER DOUBLY-SELECTIVE FADING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    Tian Jinfeng; Jiang Yonglei; Chen Huaxia; Hu Honglin

    2011-01-01

    In this paper,using cyclostationarity-based sensing method to detect the presence of Orthogonal Frequency Division Multiplexing (OFDM) signal over doubly-selective fading channels is studied.By approximating the channel with Basis Expansion Model (BEM),we derive the second-order cyclostationary statistics of the received OFDM signal over doubly-selective fading channels.Theoretical analysis indicates that new cyclostationary signatures produced by Doppler spread and multipath delay can be further exploited in the detecting process.Simulation examples demonstrate that the sensing methods using channel-induced cyclostationary features provide substantial improvements on detection performance.

  17. Control of helium activity in the fuel reactor channels

    International Nuclear Information System (INIS)

    The objective of this task was to study the possibility of detecting a damaged fuel channel, and to introduce automated procedure for continuous control of reactor channels during operation. The existing control systems at the RA reactor (permanent control of heavy water and helium activity, radiation monitoring of heavy water and helium system, measurements of fire damp gas percent) are not sufficient for fast detection of fuel element failures. Since a 'hot' fuel channel cannot be removed from the core because it should be cooled in the core by heavy water circulation, it is not possible to prevent contamination of heavy water by fission products. It is concluded that it is not indispensable to detect the failed fuel element promptly, i.e. that tome is not a critical issue

  18. Selectivity sequences in a model calcium channel: role of electrostatic field strength

    OpenAIRE

    Krauss, Daniel; Eisenberg, Bob; Gillespie, Dirk

    2011-01-01

    The energetics that give rise to selectivity sequences of ionic binding selectivity of Li+, Na+, K+, Rb+, and Cs+ in a model of a calcium channel are considered. This work generalizes Eisenman’s classic treatment (Biophys J 2(Suppl. 2):259, 1962) by including multiple, mobile binding site oxygens that coordinate many permeating ions (all modeled as charged, hard spheres). The selectivity filter of the model calcium channel allows the carboxyl terminal groups of glutamate and aspartate side ch...

  19. Cannabinoid Control of Learning and Memory through HCN Channels.

    Science.gov (United States)

    Maroso, Mattia; Szabo, Gergely G; Kim, Hannah K; Alexander, Allyson; Bui, Anh D; Lee, Sang-Hun; Lutz, Beat; Soltesz, Ivan

    2016-03-01

    The mechanisms underlying the effects of cannabinoids on cognitive processes are not understood. Here we show that cannabinoid type-1 receptors (CB1Rs) control hippocampal synaptic plasticity and spatial memory through the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that underlie the h-current (Ih), a key regulator of dendritic excitability. The CB1R-HCN pathway, involving c-Jun-N-terminal kinases (JNKs), nitric oxide synthase, and intracellular cGMP, exerts a tonic enhancement of Ih selectively in pyramidal cells located in the superficial portion of the CA1 pyramidal cell layer, whereas it is absent from deep-layer cells. Activation of the CB1R-HCN pathway impairs dendritic integration of excitatory inputs, long-term potentiation (LTP), and spatial memory formation. Strikingly, pharmacological inhibition of Ih or genetic deletion of HCN1 abolishes CB1R-induced deficits in LTP and memory. These results demonstrate that the CB1R-Ih pathway in the hippocampus is obligatory for the action of cannabinoids on LTP and spatial memory formation. PMID:26898775

  20. Towards Automatic Decentralized Control Structure Selection

    DEFF Research Database (Denmark)

    Jørgensen, John Bagterp; Jørgensen, Sten Bay

    2000-01-01

    A subtask in integration of design and control of chemical processes is the selection of a control structure. Automating the selection of the control structure enables sequential integration of process and control design. As soon as the process is specified or computed, a structure for...... decentralized control is determined automatically, and the resulting decentralized control structure is automatically tuned using standard techniques. Dynamic simulation of the resulting process system gives immediate feedback to the process design engineer regarding practical operability of the process. The...... control structure selection problem is formulated as a special MILP employing cost coefficients which are computed using Parseval's theorem combined with RGA and IMC concepts. This approach enables selection and tuning of large-scale plant-wide decentralized controllers through efficient combination of...

  1. Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels

    Directory of Open Access Journals (Sweden)

    D. Boda

    2015-03-01

    Full Text Available The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity filter of the channel is used. The selectivity filter of this channel type contains aspartate (D, glutamate (E, lysine (K, and alanine (A residues (the DEKA locus. We use Grand Canonical Monte Carlo simulations to compute equilibrium binding selectivity in the selectivity filter and to obtain various terms of the excess chemical potential from a particle insertion procedure based on Widom's method. We show that K+ ions in competition with Na+ are efficiently excluded from the selectivity filter due to entropic hard sphere exclusion. The dielectric constant of protein has no effect on this selectivity. Ca2+ ions, on the other hand, are excluded from the filter due to a free energetic penalty which is enhanced by the low dielectric constant of protein.

  2. Towards Automatic Decentralized Control Structure Selection

    DEFF Research Database (Denmark)

    A subtask in integration of design and control of chemical processes is the selection of a control structure. Automating the selection of the control structure enables sequential integration of process and controld esign. As soon as the process is specified or computed, a structure for...... decentralized control is determined automatically, and the resulting decentralized control structure is automatically tuned using standard techniques. Dynamic simulation of the resulting process system gives immediate feedback to the process design engineer regarding practical operability of the process. The...... control structure selection problem is formulated as a special MILP employing cost coefficients which are computed using Parseval's theorem combined with RGA and IMC concepts. This approach enables selection and tuning of large-scale plant-wide decentralized controllers through efficient combination of...

  3. Discovery and characterization of a potent and selective inhibitor of Aedes aegypti inward rectifier potassium channels.

    Science.gov (United States)

    Raphemot, Rene; Rouhier, Matthew F; Swale, Daniel R; Days, Emily; Weaver, C David; Lovell, Kimberly M; Konkel, Leah C; Engers, Darren W; Bollinger, Sean R; Bollinger, Sean F; Hopkins, Corey; Piermarini, Peter M; Denton, Jerod S

    2014-01-01

    Vector-borne diseases such as dengue fever and malaria, which are transmitted by infected female mosquitoes, affect nearly half of the world's population. The emergence of insecticide-resistant mosquito populations is reducing the effectiveness of conventional insecticides and threatening current vector control strategies, which has created an urgent need to identify new molecular targets against which novel classes of insecticides can be developed. We previously demonstrated that small molecule inhibitors of mammalian Kir channels represent promising chemicals for new mosquitocide development. In this study, high-throughput screening of approximately 30,000 chemically diverse small-molecules was employed to discover potent and selective inhibitors of Aedes aegypti Kir1 (AeKir1) channels heterologously expressed in HEK293 cells. Of 283 confirmed screening 'hits', the small-molecule inhibitor VU625 was selected for lead optimization and in vivo studies based on its potency and selectivity toward AeKir1, and tractability for medicinal chemistry. In patch clamp electrophysiology experiments of HEK293 cells, VU625 inhibits AeKir1 with an IC50 value of 96.8 nM, making VU625 the most potent inhibitor of AeKir1 described to date. Furthermore, electrophysiology experiments in Xenopus oocytes revealed that VU625 is a weak inhibitor of AeKir2B. Surprisingly, injection of VU625 failed to elicit significant effects on mosquito behavior, urine excretion, or survival. However, when co-injected with probenecid, VU625 inhibited the excretory capacity of mosquitoes and was toxic, suggesting that the compound is a substrate of organic anion and/or ATP-binding cassette (ABC) transporters. The dose-toxicity relationship of VU625 (when co-injected with probenecid) is biphasic, which is consistent with the molecule inhibiting both AeKir1 and AeKir2B with different potencies. This study demonstrates proof-of-concept that potent and highly selective inhibitors of mosquito Kir channels can

  4. Performance of Downlink UTRAN LTE under Control Channel Constraints

    DEFF Research Database (Denmark)

    López Villa, Dimas; Úbeda Castellanos, Carlos; Kovács, István Z.; Frederiksen, Frank; Pedersen, Klaus I.

    Dynamic time-frequency domain packet scheduling algorithms in the shared channel of downlink orthogonal Frequency Division Multiple Access (OFDMA) systems have been shown to achieve high multi-user diversity scheduling gains. However, the flexibility is obtained at the cost of additional control...

  5. Two-pulse laser control of bond-selective fragmentation

    DEFF Research Database (Denmark)

    Amstrup, Bjarne; Henriksen, Niels Engholm

    1996-01-01

    We elaborate on a two-pulse (pump-pump) laser control scheme for selective bond-breaking in molecules [Amstrup and Henriksen, J. Chem. Phys. 97, 8285 (1992)]. We show, in particular, that with this scheme one can overcome the obstacle of intramolecular vibrational relaxation. As an example, we...... consider an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18. It is shown that asymmetric bond stretching can be created in simple (intense) laser fields. We predict that an alternating high selectivity between the channels O-16+(OO)-O-16-O-18 and (OO)-O-16-O-16+ O-18 can be...

  6. Control Configuration Selection for Multivariable Descriptor Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Stoustrup, Jakob

    2012-01-01

    Control configuration selection is the procedure of choosing the appropriate input and output pairs for the design of SISO (or block) controllers. This step is an important prerequisite for a successful industrial control strategy. In industrial practices it is often the case that the system, which...... systems, hydraulic systems to heat transfer, and chemical processes. The focus of this paper is on the problem of control configuration selection for multivariable descriptor systems. A gramian-based interaction measure for control configuration selection of such processes is described in this paper....... The proposed MIMO interaction measure is the extension of its gramian-based analogous counterpart, which has been proposed for the input–output pairing as well as for the controller architecture selection of the processes with the standard state-space form. The main advantage of this interaction measure...

  7. From pan-reactive KV7 channel opener to subtype selective opener/inhibitor by addition of a methyl group

    DEFF Research Database (Denmark)

    Blom, Sigrid Marie; Rottländer, Mario; Kehler, Jan;

    2014-01-01

    -activity relationship of acrylamide KV7 channel openers and the effects of these compounds on mutant KV7 channels, we have designed and synthesized a novel KV7 channel modulator with a unique profile. The compound, named SMB-1, is an inhibitor of KV7.2 and an activator of KV7.4. SMB-1 inhibits KV7.2 by reducing the.......2-5 opener retigabine indicate that SMB-1 binds within the same pocket as retigabine for both inhibition of KV7.2 and activation of KV7.4. SMB-1 may serve as a valuable tool for KV7 channel research and may be used as a template for further design of better subtype selective KV7 channel modulators. A......The voltage-gated potassium channels of the KV7 family (KV7.1-5) play important roles in controlling neuronal excitability and are therefore attractive targets for treatment of CNS disorders linked to hyperexcitability. One of the main challenges in developing KV7 channel active drugs has been to...

  8. Proactive Relay Selection with Joint Impact of Hardware Impairment and Co-channel Interference

    OpenAIRE

    Duy, Tran Trung; Duong, Trung Q.; da Costa, Daniel Benevides; Bao, Vo Ngyugen Quoc; Elkashlan, Maged

    2015-01-01

    In this paper, we investigate the end-to-end performance of dual-hop proactive decode-and-forward relaying networks with Nth best relay selection in the presence of two practical deleterious effects: i) hardware impairment and ii) cochannel interference. In particular, we derive new exact and asymptotic closed-form expressions for the outage probability and average channel capacity of Nth best partial and opportunistic relay selection schemes over Rayleigh fading channels. Insightful discussi...

  9. Streaming potentials in gramicidin channels measured with ion-selective microelectrodes.

    OpenAIRE

    Tripathi, S; Hladky, S B

    1998-01-01

    Streaming potentials have been measured for gramicidin channels with a new method employing ion-selective microelectrodes. It is shown that ideally ion-selective electrodes placed at the membrane surface record the true streaming potential. Using this method for ion concentrations below 100 mM, approximately seven water molecules are transported whenever a sodium, potassium, or cesium ion, passes through the channel. This new method confirms earlier measurements (Rosenberg, P.A., and A. Finke...

  10. Selection of marketing channels for the distribution of industrial enterprises’ innovative products

    OpenAIRE

    L.O. Syhyda

    2014-01-01

    The aim of the article. The aim of the study is to determine the stages by which it is possible to select among existing marketing channels of the enterprise ones that would be best to use in innovative products’ distribution. The results of the analysis. The author proposes stages by following which it is possible to choose marketing channels for the innovative products’ distribution at industrial enterprises. At the first stage of marketing channels’ selection diagnostics of marketing...

  11. Wavelet Packet Function Based RAKE/Adaptive Multichannel DFE for a WPMA System over Frequency Selective Rayleigh Fading Channels

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaodong; BI Guangguo

    2001-01-01

    A wavelet packet function based multiple access (WPMA) system is developed in this paper to maximize capacity and improve receiver performance over frequency selective multipath fading channels. To design an efficient receiver that mitigates residual multiple access interference (MAI) and intersymbol interference, while improving received signal-to-interference and noise ratio (SINR) simultaneously on the uplink, a multichannel decision feedback equalizer (DFE) following a wavelet packet function based RAKE receiver is proposed. Simulation results show that, over GSM TU channels the developed receiver performs quite well if the power of each user is perfectly controlled or the space diversity combining (SDC) technique is applied.

  12. Synthetic Channel-forming Peptides and Ion Selectivity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Introduction Peptides made up of alternating L- and D- amino acids can form β-helices as in gramicidin A or cyclic peptides that aggregate to form tubes[1]. In both cases the structures are hollow with all the side chains projecting outwards. Kennedy et al. [2] postulated that peptides having the (LLLD)n configuration could form helices with every fourth side chain projecting inward.It is a fact that synthetic N-formyl-( LeuSerLeuGly)6-OH, when added to a lipid bilayer, dimerizes, to form ion channels having conductances greater than that of gramicidin.

  13. A Bintree Energy Approach for Colour Image Segmentation Using Adaptive Channel Selection

    Institute of Scientific and Technical Information of China (English)

    TU Sheng-xian; ZHANG Su; CHEN Ya-zhu; XIAO Chang-yan; ZHANG Lei

    2008-01-01

    A new hierarchical approach called bintree energy segmentation was presented for color image seg-mentation. The image features are extracted by adaptive clustering on multi-channel data at each level and used as the criteria to dynamically select the best chromatic channel, where the segmentation is carried out. In this approach, an extended direct energy computation method based on the Chan-Vese model was proposed to segment the selected channel, and the segmentation outputs are then fused with other channels into new images,from which a new channel with better features is selected for the second round segmentation. This procedure is repeated until the preset condition is met. Finally, a binary segmentation tree is formed, in which each leaf represents a class of objects with a distinctive color. To facilitate the data organization, image background is employed in segmentation and channels fusion. The bintree energy segmentation exploits color information involved in all channels data and tries to optimize the global segmentation result by choosing the "best" chan-nel for segmentation at each level. The experiments show that the method is effective in speed, accuracy and flexibility.

  14. MIMO-DFE BASED SPACE-TIME RECEIVER OVER FREQUENCY SELECTIVE CHANNELS WITH LIMITED ERROR PROPAGATION

    Institute of Scientific and Technical Information of China (English)

    Shen Liyun; Hu Bo

    2005-01-01

    MIMO-DFE(Multiple-Input-Multiple-Output Decision Feedback Equalizer) based receiver architectures are researched recently to detect signals in BLAST(Bell laboratories LAyered Space-Time) over frequency-selective channels. Due to their recursive structure, these receivers may suffer from error propagation which results in an overall mean square error degradation. An MIMO-DFE based BLAST receiver with limited error propagation to combat frequencyselective channel is proposed, which employs both norm constraint on feedback filter taps and soft decision device. Simulation results show that the proposed receiver outperforms conventional ones in various frequency selective channels.

  15. Voltage-Gated Potassium Channels: A Structural Examination of Selectivity and Gating.

    Science.gov (United States)

    Kim, Dorothy M; Nimigean, Crina M

    2016-01-01

    Voltage-gated potassium channels play a fundamental role in the generation and propagation of the action potential. The discovery of these channels began with predictions made by early pioneers, and has culminated in their extensive functional and structural characterization by electrophysiological, spectroscopic, and crystallographic studies. With the aid of a variety of crystal structures of these channels, a highly detailed picture emerges of how the voltage-sensing domain reports changes in the membrane electric field and couples this to conformational changes in the activation gate. In addition, high-resolution structural and functional studies of K(+) channel pores, such as KcsA and MthK, offer a comprehensive picture on how selectivity is achieved in K(+) channels. Here, we illustrate the remarkable features of voltage-gated potassium channels and explain the mechanisms used by these machines with experimental data. PMID:27141052

  16. Study of Internal Channel Surface Roughnesses Manufactured by Selective Laser Melting in Aluminum and Titanium Alloys

    Science.gov (United States)

    Pakkanen, Jukka; Calignano, Flaviana; Trevisan, Francesco; Lorusso, Massimo; Ambrosio, Elisa Paola; Manfredi, Diego; Fino, Paolo

    2016-04-01

    Interest in additive manufacturing (AM) has gained considerable impetus over the past decade. One of the driving factors for AM success is the ability to create unique designs with intrinsic characteristics as, e.g., internal channels used for hydraulic components, cooling channels, and heat exchangers. However, a couple of the main problems in internal channels manufactured by AM technologies are the high surface roughness obtained and the distortion of the channel shape. There is still much to understand in these design aspects. In this study, a cylindrical geometry for internal channels to be built with different angles with respect to the building plane in AlSi10Mg and Ti6Al4V alloys by selective laser melting was considered. The internal surfaces of the channels produced in both materials were analyzed by means of a surface roughness tester and by optical and electron microscopy to evaluate the effects of the material and design choices.

  17. Study of Internal Channel Surface Roughnesses Manufactured by Selective Laser Melting in Aluminum and Titanium Alloys

    Science.gov (United States)

    Pakkanen, Jukka; Calignano, Flaviana; Trevisan, Francesco; Lorusso, Massimo; Ambrosio, Elisa Paola; Manfredi, Diego; Fino, Paolo

    2016-08-01

    Interest in additive manufacturing (AM) has gained considerable impetus over the past decade. One of the driving factors for AM success is the ability to create unique designs with intrinsic characteristics as, e.g., internal channels used for hydraulic components, cooling channels, and heat exchangers. However, a couple of the main problems in internal channels manufactured by AM technologies are the high surface roughness obtained and the distortion of the channel shape. There is still much to understand in these design aspects. In this study, a cylindrical geometry for internal channels to be built with different angles with respect to the building plane in AlSi10Mg and Ti6Al4V alloys by selective laser melting was considered. The internal surfaces of the channels produced in both materials were analyzed by means of a surface roughness tester and by optical and electron microscopy to evaluate the effects of the material and design choices.

  18. Quality Control Of Selected Pesticides With GC

    International Nuclear Information System (INIS)

    The practical quality control of selected pesticides with GC is treated. Detailed descriptions are given on materials and methods used, including sample preparation and GC operating conditions. The systematic validation of multi methods is described, comprising performance characteristics in routine analysis, like selectivity, specificity etc. This is illustrated by chromatograms, calibration curves and tables derived from real laboratory data. (author)

  19. 1st International Conference on Hydraulic Design in Water Resources Engineering : Channels and Channel Control Structures

    CERN Document Server

    1984-01-01

    The development of water resources has proceeded at an amazing speed around the world in the last few decades. The hydraulic engineer has played his part: in constructing much larger artificial channels than ever before, larger and more sophisticated control structures, and systems of irrigation, drainage and water supply channels in which the flow by its nature is complex and unsteady requiring computer-based techniques at both the design and operation stage. It seemed appropriate to look briefly at some of the developments in hydraulic design resulting from this situation. Hence the idea of the Conference was formed. The Proceedings of the Conference show that hydraulic engineers have been able to acquire a very substantial base of design capability from the experience of the period referred to. The most outstanding development to have occurred is in the combination of physical and mathematical modelling, which in hydraulic engineering has followed a parallel path to that in other branches of engineering sc...

  20. Lysine and the Na+/K+ Selectivity in Mammalian Voltage-Gated Sodium Channels.

    Science.gov (United States)

    Li, Yang; Liu, Huihui; Xia, Mengdie; Gong, Haipeng

    2016-01-01

    Voltage-gated sodium (Nav) channels are critical in the generation and transmission of neuronal signals in mammals. The crystal structures of several prokaryotic Nav channels determined in recent years inspire the mechanistic studies on their selection upon the permeable cations (especially between Na+ and K+ ions), a property that is proposed to be mainly determined by residues in the selectivity filter. However, the mechanism of cation selection in mammalian Nav channels lacks direct explanation at atomic level due to the difference in amino acid sequences between mammalian and prokaryotic Nav homologues, especially at the constriction site where the DEKA motif has been identified to determine the Na+/K+ selectivity in mammalian Nav channels but is completely absent in the prokaryotic counterparts. Among the DEKA residues, Lys is of the most importance since its mutation to Arg abolishes the Na+/K+ selectivity. In this work, we modeled the pore domain of mammalian Nav channels by mutating the four residues at the constriction site of a prokaryotic Nav channel (NavRh) to DEKA, and then mechanistically investigated the contribution of Lys in cation selection using molecular dynamics simulations. The DERA mutant was generated as a comparison to understand the loss of ion selectivity caused by the K-to-R mutation. Simulations and free energy calculations on the mutants indicate that Lys facilitates Na+/K+ selection by electrostatically repelling the cation to a highly Na+-selective location sandwiched by the carboxylate groups of Asp and Glu at the constriction site. In contrast, the electrostatic repulsion is substantially weakened when Lys is mutated to Arg, because of two intrinsic properties of the Arg side chain: the planar geometric design and the sparse charge distribution of the guanidine group. PMID:27584582

  1. Residential Noise Control Requirements for Powerline Communications Channel

    OpenAIRE

    Guillen, Edward; Lopez, Julian; Padilla, Daniel

    2010-01-01

    Noises on powerline communication channels such as coloured noise, narrow band noise, periodic impulsive noise and asynchronous impulsive noise affect PLC network throughput. However, these noises can be successfully controlled by band-pass and bandstop filters installed on strategic PLC network connection points. It's necessary to establish a model to probe if the noise measurements on this work can be applied on industrial environments and if the noise can affect PLC networks installed on n...

  2. A Wearable Channel Selection-Based Brain-Computer Interface for Motor Imagery Detection.

    Science.gov (United States)

    Lo, Chi-Chun; Chien, Tsung-Yi; Chen, Yu-Chun; Tsai, Shang-Ho; Fang, Wai-Chi; Lin, Bor-Shyh

    2016-01-01

    Motor imagery-based brain-computer interface (BCI) is a communication interface between an external machine and the brain. Many kinds of spatial filters are used in BCIs to enhance the electroencephalography (EEG) features related to motor imagery. The approach of channel selection, developed to reserve meaningful EEG channels, is also an important technique for the development of BCIs. However, current BCI systems require a conventional EEG machine and EEG electrodes with conductive gel to acquire multi-channel EEG signals and then transmit these EEG signals to the back-end computer to perform the approach of channel selection. This reduces the convenience of use in daily life and increases the limitations of BCI applications. In order to improve the above issues, a novel wearable channel selection-based brain-computer interface is proposed. Here, retractable comb-shaped active dry electrodes are designed to measure the EEG signals on a hairy site, without conductive gel. By the design of analog CAR spatial filters and the firmware of EEG acquisition module, the function of spatial filters could be performed without any calculation, and channel selection could be performed in the front-end device to improve the practicability of detecting motor imagery in the wearable EEG device directly or in commercial mobile phones or tablets, which may have relatively low system specifications. Finally, the performance of the proposed BCI is investigated, and the experimental results show that the proposed system is a good wearable BCI system prototype. PMID:26861347

  3. Partial relay selection based on shadowing side information over generalized composite fading channels

    KAUST Repository

    Yilmaz, Ferkan

    2011-11-01

    In this paper, in contrast to the relay selection protocols available in the literature, we propose a partial relay selection protocol utilizing only the shadowing side information of the relays instead of their full channel side information in order to select a relay in a dual-hop relaying system through the available limited feedback channels and power budget. We then presented an exact unified performance expression combining the average bit error probability, ergodic capacity, and moments-generating function of the proposed partial relay selection over generalized fading channels. Referring to the unified performance expression introduced in [1], we explicitly offer a generic unified performance expression that can be easily calculated and that is applicable to a wide variety of fading scenarios. Finally, as an illustration of the mathematical formalism, some numerical and simulation results are generated for an extended generalized-K fading environment, and these numerical and simulation results are shown to be in perfect agreement. © 2011 IEEE.

  4. Channel selection in e-commerce age: A strategic analysis of co-op advertising models

    Directory of Open Access Journals (Sweden)

    Yongmei Liu

    2013-03-01

    Full Text Available Purpose: The purpose of this paper is to develop and compare two co-op advertising models: advertising model under traditional channel and co-op advertising model under dual channel, to select optimal channel structure to sell products for manufacturer and to derive optimal co-op advertising strategies for the manufacturer and the retailer.Design/methodology/approach: Stackelberg game theoretical is used to develop two co-op advertising models: co-op advertising model under traditional channel and co-op advertising model under dual channel. Then we compare the two models to select optimal channel structure to sell products for manufacturer and to derive optimal co-op advertising strategies for the manufacturer and the retailer. Furthermore, we analyze the impact of product web-fit on these optimal strategies and illustrate by some numeral examples. Based on our results, we provide some significant theories and managerial insights, and derive some probable paths of future research.Findings: We provide a framework for researching optimal co-op advertising strategies in a two-level supply chain considering different marketing channel structures. First, we discuss the traditional channel co-op adverting model and the dual channel co-op advertising model based on Stackelberg game theoretical, and we derive optimal co-op advertising strategies. Next, comparisons of these two channel structures are discussed and we find that the manufacturer always benefits from dual channel. But the retailer not always benefits from dual channel structure, and dual channel structure is better than retail channel with certain conditions. Also, the optimal co-op advertising strategies for the manufacturer and the retailer are obtained.Research limitations/implications: First, we focus on the aforementioned two channel structures; a further comparison with other channel structures can be investigated. Second, we ignore some factors that influence the demand of product

  5. Sediment control - an appropriate solution for small irrigation channels

    International Nuclear Information System (INIS)

    Sediment control is one of the key factors considered prior to the design of an irrigation channel. When the channel takes off from its headworks, its slope is usually smaller than that of the parent stream to obtain required head. If the sediment load is heavy then the channel can not maintain equilibrium since the high influx can not be transported fully due to its small gradient. This results in the deposition of part incoming sediment in the channel itself. A typical irrigation intake suitable for small schemes, which consists of a simple settling basin with double orifice: one at the inlet from the river and the other at the outlet to the canal. The basin is provided with a side spill weir near its downstream end, to discharge flows in excess of the maximum canal capacity. This paper deals with the experimental study of such an arrangement. Different flows were run covering a range of levels in the river, from minimum to flood flows to check the hydraulic performance of the layout and in particular to study its effectiveness in settling sediment at low flows and avoiding excessive sediment input to the canal during flood. (author)

  6. Cation gating and selectivity in a purified, reconstituted, voltage-dependent sodium channel

    International Nuclear Information System (INIS)

    In excitable membranes, the voltage-dependent sodium channel controls the primary membrane conductance change necessary for the generation of an action potential. Over the past four decades, the time- and voltage-dependent sodium currents gated by this channel have been thoroughly documented with increasingly sophisticated voltage-clamp techniques. Recent advances in the biochemistry of membrane proteins have led to the solubilization and purification of this channel protein from nerve (6) and from muscle (4) or muscle-derived (1) membranes, and have provided an approach to the correlation of the channel's molecular structure with its functional properties. Each of these sodium channel preparations appears to contain a large glycoprotein either as its sole component (2) or in association with several small subunits (6, 3). Evidence that these purified proteins represent the excitable membrane sodium channel is presented. 8 refs., 1 fig., 1 tab

  7. The Enhanced Decoding Method for QO-SFBC System in Frequency Selective Fading Channel Environment

    Directory of Open Access Journals (Sweden)

    Young-il Min

    2011-03-01

    Full Text Available In this paper, we propose an enhanced decoding method to improve the performance of the quasi orthogonal (QO-space frequency block coding (SFBC in frequency selective fading channel environment. Generally, QO-SFBC obtains full diversity gain with more than two transmit antennas by using the constellation rotation in flat fading channel. However, QO-SFBC provides less diversity gain in frequency selective fading channel, because the discrepancy of channel frequency responses (CFRs at adjacent subcarriers causes additive interferences. Although the conventional method using the simple averaging scheme for all CFRs at adjacent subcarriers can be effective for mitigating interferences, it is not quite robust to variation of CFRs, especially in high Doppler frequency environments. Therefore, to achieve better diversity gain in frequency selective fading channel environment, the selective averaged QO-SFBC decoding method based on mathematical analysis considering each CFR of elements in QO-SFBC encoding block is proposed. By using computer simulation, we show that the proposed method can provide better performance compared with the conventional methods and verify that the proposed method is attractive and suitable for implementation with stable operation when frequency selectivity is high.

  8. Wavelength-selective fluorescence in ion channels formed by gramicidin A in membranes

    Indian Academy of Sciences (India)

    Amitabha Chattopadhyay; Satinder S Rawat

    2007-03-01

    Gramicidins are linear peptides that form ion channels that are specific for monovalent cations in membranes. The tryptophan residues in the gramicidin channel play a crucial role in the organization and function of the channel. The natural mixture of gramicidins, denoted as gramicidin A', consists of mostly gramicidin A, but also contains gramicidins B, C and D as minor components. We have previously shown that the tryptophan residues in ion channels formed by the naturally occurring peptide, gramicidin A', display wavelength-dependent fluorescence characteristics due to the motionally restricted environment in which they are localized. In order to check the influence of ground-state heterogeneity in the observed wavelength-selective fluorescence of gramicidin A' in membranes, we performed similar experiments with pure gramicidin A in model membranes. Our results show that the observed wavelength-selective fluorescence characteristics of naturally occurring gramicidin A' are not due to groundstate heterogeneity.

  9. On a multi-channel transportation loss system with controlled input and controlled service

    Directory of Open Access Journals (Sweden)

    Jewgeni Dshalalow

    1987-01-01

    Full Text Available A multi-channel loss queueing system is investigated. The input stream is a controlled point process. The service in each of m parallel channels depends on the state of the system at certain moments of time when input and service may be controlled. To obtain explicitly the limiting distribution of the main process (Zt (the number of busy channels in equilibrium, an auxiliary three dimensional process with two additional components (one of them is a semi-Markov process is treated as semi-regenerative process. An optimization problem is discussed. Simple expressions for an objective function are derived.

  10. Sodium channel selectivity and conduction: Prokaryotes have devised their own molecular strategy

    OpenAIRE

    Finol-Urdaneta, Rocio K.; Wang, Yibo; Al-Sabi, Ahmed; Zhao, Chunfeng; Noskov, Sergei Y.; French, Robert J.

    2014-01-01

    Striking structural differences between voltage-gated sodium (Nav) channels from prokaryotes (homotetramers) and eukaryotes (asymmetric, four-domain proteins) suggest the likelihood of different molecular mechanisms for common functions. For these two channel families, our data show similar selectivity sequences among alkali cations (relative permeability, Pion/PNa) and asymmetric, bi-ionic reversal potentials when the Na/K gradient is reversed. We performed coordinated experimental and compu...

  11. All-optical control of electron trapping in plasma channels

    Science.gov (United States)

    Kalmykov, Serguei Y.; Shadwick, Bradley A.; Davoine, Xavier

    2013-10-01

    Generation of background-free, polychromatic electron beams using laser plasma acceleration in longitudinally uniform, mm-length dense plasma channels is demonstrated. Periodic self-injection and acceleration transfers up to 10 percents of the drive pulse energy to several 100-pC charge, GeV-scale-energy electron bunches, each having a few-percent energy spread. Negative chirp of the broad-bandwidth (up to 400 nm), few-Joule-energy driver reduces the nonlinear frequency red-shift, preventing rapid self-steepening of the pulse, whereas the channel suppresses diffraction of the pulse leading edge. The pulse thus remains uncompressed through electron dephasing, strongly reducing unwanted continuous injection. As a bonus, delayed self-compression of the driver extends the dephasing length, boosting electron energy to the GeV level. The number of the quasi-monoenergetic bunches, their charge, energy, and energy separation can be controlled by varying the channel radius and the acceleration length, whereas accumulation of the noise (viz. continuously injected charge) is prevented by the proper dispersion control via negative chirp of the pulse. These clean polychromatic beams can drive tunable, multi-color gamma-ray Compton sources. Supported by the U.S. DOE Grant DE-SC0008382, NSF Grant PHY-1104683, and DOD AFOSR Grant FA9550-11-1-0157. The CALDER-Circ simulations were performed using HPC resources of GENCI-CCRT and GENCI-CINES (grant 2013-057027).

  12. Performance of Selection Combining for Differential Amplify-and-Forward Relaying Over Time-Varying Channels

    OpenAIRE

    Avendi, M. R.; Nguyen, Ha H.

    2014-01-01

    Selection combining (SC) at the destination for differential amplify-and-forward (AF) relaying is attractive as it does not require channel state information as compared to the semi maximum-ratio-combining (semi-MRC) while delivering close performance. Performance analysis of the SC scheme was recently reported but only for the case of slow-fading channels. This paper provides an exact average bit-error-rate (BER) of the SC scheme over a general case of time-varying Rayleigh fading channels a...

  13. Robust EEG Channel Selection across Subjects for Brain-Computer Interfaces

    Directory of Open Access Journals (Sweden)

    Lal Thomas Navin

    2005-01-01

    Full Text Available Most EEG-based brain-computer interface (BCI paradigms come along with specific electrode positions, for example, for a visual-based BCI, electrode positions close to the primary visual cortex are used. For new BCI paradigms it is usually not known where task relevant activity can be measured from the scalp. For individual subjects, Lal et al. in 2004 showed that recording positions can be found without the use of prior knowledge about the paradigm used. However it remains unclear to what extent their method of recursive channel elimination (RCE can be generalized across subjects. In this paper we transfer channel rankings from a group of subjects to a new subject. For motor imagery tasks the results are promising, although cross-subject channel selection does not quite achieve the performance of channel selection on data of single subjects. Although the RCE method was not provided with prior knowledge about the mental task, channels that are well known to be important (from a physiological point of view were consistently selected whereas task-irrelevant channels were reliably disregarded.

  14. Discovery of novel tetrahydroisoquinoline derivatives as orally active N-type calcium channel blockers with high selectivity for hERG potassium channels.

    Science.gov (United States)

    Ogiyama, Takashi; Inoue, Makoto; Honda, Shugo; Yamada, Hiroyoshi; Watanabe, Toshihiro; Gotoh, Takayasu; Kiso, Tetsuo; Koakutsu, Akiko; Kakimoto, Shuichiro; Shishikura, Jun-ichi

    2014-12-15

    N-type calcium channels represent a promising target for the treatment of neuropathic pain. The selective N-type calcium channel blocker ziconotide ameliorates severe chronic pain but has a narrow therapeutic window and requires intrathecal administration. We identified tetrahydroisoquinoline derivative 1a as a novel potent N-type calcium channel blocker. However, this compound also exhibited potent inhibitory activity against hERG channels. Structural optimizations led to identification of (1S)-(1-cyclohexyl-3,4-dihydroisoquinolin-2(1H)-yl)-2-{[(1-hydroxycyclohexyl)methyl]amino}ethanone ((S)-1h), which exhibited high selectivity for hERG channels while retaining potency for N-type calcium channel inhibition. (S)-1h went on to demonstrate in vivo efficacy as an orally available N-type calcium channel blocker in a rat spinal nerve ligation model of neuropathic pain. PMID:25456079

  15. Selective control of HOD photodissociation using CW lasers

    Indian Academy of Sciences (India)

    Manabendra Sarma; S Adhikari; Manoj K Mishra

    2007-09-01

    Selective control of HOD photodissociation (H-O + D ← HOD → H + O-D) has been theoretically investigated using CW lasers with appropriate carrier frequency and |0, 0〉, |0, 1〉 and |0, 2〉 with zero quantum of excitation in the O-H bond and zero, one and two quanta of excitation in the O-D bond as the initial states. Results indicate that the O-H bond in HOD can be selectively dissociated with a maximum flux of 87% in the H + O-D channel from the ground vibrational state |0, 0〉. For the O-D bond dissociation, it requires two quanta of excitation (|0, 2〉) in the O-D mode to obtain 83% flux in the H-O + D channel. Use of a two colour laser set-up in conjunction with the field optimized initial state (FOIST) scheme to obtain an optimal linear combination of |0, 0〉 and |0, 1〉 vibrational states as the initial state provides an additional 7% improvement to flux in the H-O + D channel as compared to that from the pure |0, 1〉 state.

  16. Autocrine-Based Selection of Drugs That Target Ion Channels from Combinatorial Venom Peptide Libraries.

    Science.gov (United States)

    Zhang, Hongkai; Du, Mingjuan; Xie, Jia; Liu, Xiao; Sun, Jingying; Wang, Wei; Xin, Xiu; Possani, Lourival D; Yea, Kyungmoo; Lerner, Richard A

    2016-08-01

    Animal venoms represent a rich source of pharmacologically active peptides that interact with ion channels. However, a challenge to discovering drugs remains because of the slow pace at which venom peptides are discovered and refined. An efficient autocrine-based high-throughput selection system was developed to discover and refine venom peptides that target ion channels. The utility of this system was demonstrated by the discovery of novel Kv1.3 channel blockers from a natural venom peptide library that was formatted for autocrine-based selection. We also engineered a Kv1.3 blocker peptide (ShK) derived from sea anemone to generate a subtype-selective Kv1.3 blocker with a long half-life in vivo. PMID:27197631

  17. Simultaneous Channel and Feature Selection of Fused EEG Features Based on Sparse Group Lasso

    Directory of Open Access Journals (Sweden)

    Jin-Jia Wang

    2015-01-01

    Full Text Available Feature extraction and classification of EEG signals are core parts of brain computer interfaces (BCIs. Due to the high dimension of the EEG feature vector, an effective feature selection algorithm has become an integral part of research studies. In this paper, we present a new method based on a wrapped Sparse Group Lasso for channel and feature selection of fused EEG signals. The high-dimensional fused features are firstly obtained, which include the power spectrum, time-domain statistics, AR model, and the wavelet coefficient features extracted from the preprocessed EEG signals. The wrapped channel and feature selection method is then applied, which uses the logistical regression model with Sparse Group Lasso penalized function. The model is fitted on the training data, and parameter estimation is obtained by modified blockwise coordinate descent and coordinate gradient descent method. The best parameters and feature subset are selected by using a 10-fold cross-validation. Finally, the test data is classified using the trained model. Compared with existing channel and feature selection methods, results show that the proposed method is more suitable, more stable, and faster for high-dimensional feature fusion. It can simultaneously achieve channel and feature selection with a lower error rate. The test accuracy on the data used from international BCI Competition IV reached 84.72%.

  18. Secured Communication over Frequency-Selective Fading Channels: A Practical Vandermonde Precoding

    Directory of Open Access Journals (Sweden)

    Mari Kobayashi

    2009-01-01

    Full Text Available We study the frequency-selective broadcast channel with confidential messages (BCC where the transmitter sends a confidential message to receiver 1 and a common message to receivers 1 and 2. In the case of a block transmission of N symbols followed by a guard interval of L symbols, the frequency-selective channel can be modeled as a N×(N+L Toeplitz matrix. For this special type of multiple-input multiple-output channels, we propose a practical Vandermonde precoding that projects the confidential messages in the null space of the channel seen by receiver 2 while superposing the common message. For this scheme, we provide the achievable rate region and characterize the optimal covariance for some special cases of interest. Interestingly, the proposed scheme can be applied to other multiuser scenarios such as the K+1-user frequency-selective BCC with K confidential messages and the two-user frequency-selective BCC with two confidential messages. For each scenario, we provide the secrecy degree of freedom (s.d.o.f. region of the corresponding channel and prove the optimality of the Vandermonde precoding. One of the appealing features of the proposed scheme is that it does not require any specific secrecy encoding technique but can be applied on top of any existing powerful encoding schemes.

  19. Maitotoxin activates cation channels distinct from the receptor-activated non-selective cation channels of HL-60 cells

    OpenAIRE

    Musgrave, I. F.; Seifert, Roland; Schultz, Günter

    1994-01-01

    We investigated whether maitotoxin activates non-selective cation channels, as was recently proposed [Soergel, Yasumoto, Daly and Gusovsky (1992) Mol. Pharmacol. 41, 487-493]. Stimulation of dibutyryl cyclic AMP-differentiated HL-60 cells with the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP; 0.1 microM), the Ca(2+)-ATPase inhibitor thapsigargin (0.1 microM) or maitotoxin (25 ng/ml) resulted in an increase in cytoplasmic free calcium concentration ([Ca2+]i). Unlike ...

  20. Interfacing sensory input with motor output: does the control architecture converge to a serial process along a single channel?

    OpenAIRE

    Cornelis Van De Kamp; Peter Gawthrop; Martin Lakie

    2013-01-01

    Modular organization in control architecture may underlie the versatility of human motor control; but the nature of the interface relating sensory input through task-selection in the space of performance variables to control actions in the space of the elemental variables is currently unknown. Our central question is whether the control architecture converges to a serial process along a single channel? In discrete reaction time experiments, psychologists have firmly associated a serial single...

  1. Quantum model for a periodically driven selectivity filter in a K+ ion channel

    Science.gov (United States)

    Cifuentes, A. A.; Semião, F. L.

    2014-11-01

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions through the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field, which changes the free-energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K+ ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone, and this increases noise. Moreover, we also show that for a wide range of dephasing rates and driving frequencies, the two-pathway conduction used by the filter leads to higher ionic currents than the single-path model.

  2. Quantum model for a periodically driven selectivity filter in a K+ ion channel

    International Nuclear Information System (INIS)

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions through the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field, which changes the free-energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K+ ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone, and this increases noise. Moreover, we also show that for a wide range of dephasing rates and driving frequencies, the two-pathway conduction used by the filter leads to higher ionic currents than the single–path model. (paper)

  3. 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.

  4. Overlay Cognitive Radios With Channel-Aware Adaptive Link Selection and Buffer-Aided Relaying

    KAUST Repository

    Shaqfeh, Mohammad

    2015-08-01

    The aim of this work is to maximize the long-term average achievable rate region of a primary and a secondary source-destination pairs operating in an overlay setup over block-fading channels. To achieve this objective, we propose an opportunistic strategy to grant channel access to the primary and secondary sources based on the channel conditions in order to exploit the available multiple-link diversity gains in the system. The secondary source has causal knowledge of the primary messages and it acts as a relay of the primary source in return for getting access to the channel. To maximize the gains of relaying, the relay and destination are equipped with buffers to enable the use of channel-aware adaptive link selection. We propose and optimize different link selection policies and characterize their expected achievable rates. Also, we provide several numerical results to demonstrate the evident mutual benefits of buffer-aided cooperation and adaptive link selection to the primary and the secondary source-destination pairs. © 1972-2012 IEEE.

  5. Aluminium and hydrogen ions inhibit a mechanosensory calcium-selective cation channel

    Science.gov (United States)

    Ding, J. P.; Pickard, B. G.

    1993-01-01

    The tension-dependent activity of mechanosensory calcium-selective cation channels in excised plasmalemmal patches from onion bulb scale epidermis is modulated by pH in the physiologically meaningful range between 4.5 and 7.2. It is rapidly lowered by lowering pH and rapidly raised by raising pH. Channel activity is effectively inhibited by low levels of aluminium ions and activity can be partially restored by washing for a few minutes. We suggest that under normal conditions the sensitivity of the mechanosensory channels to pH of the wall free space plays important roles in regulation of plant activities such as growth. We further suggest that, when levels of acid and aluminium ions in the soil solution are high, they might inhibit similar sensory channels in cells of the root tip, thus contributing critically to the acid soil syndrome.

  6. Low-Complexity Iterative Receiver for Space-Time Coded Signals over Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    Mohamed Siala

    2002-05-01

    Full Text Available We propose a low-complexity turbo-detector scheme for frequency selective multiple-input multiple-output channels. The detection part of the receiver is based on a List-type MAP equalizer which is a state-reduction algorithm of the MAP algorithm using per-survivor technique. This alternative achieves a good tradeoff between performance and complexity provided a small amount of the channel is neglected. In order to induce the good performance of this equalizer, we propose to use a whitened matched filter (WMF which leads to a white-noise “minimum phase” channel model. Simulation results show that the use of the WMF yields significant improvement, particularly over severe channels. Thanks to the iterative turbo processing (detection and decoding are iterated several times, the performance loss due to the use of the suboptimum List-type equalizer is recovered.

  7. Selective Activation and Disengagement of Moral Control.

    Science.gov (United States)

    Bandura, Albert

    1990-01-01

    Analyzes psychological mechanisms by which moral control is selectively disengaged from inhumane conduct in ordinary and unusual circumstances. Explores the symptoms of moral exclusion as described in the literature. Presents categories that unify theory on moral exclusion and contribute practical classifications for use in empirical studies. (JS)

  8. Robust Control for Lateral and Longitudinal Channels of Small-Scale Unmanned Helicopters

    OpenAIRE

    Bao Feng

    2015-01-01

    Lateral and longitudinal channels are two closely related channels whose control stability influences flight performance of small-scale unmanned helicopters directly. This paper presents a robust control approach for lateral and longitudinal channels in the presence of parameter uncertainties and exogenous disturbances. The proposed control approach is performed by two steps. First, by performing system identification in frequency domain, system model of lateral and longitudinal channels can ...

  9. 78 FR 40692 - Foreign-Trade Zone 92-Gulfport, Mississippi; Application for Subzone; Channel Control Merchants...

    Science.gov (United States)

    2013-07-08

    ... Control Merchants, LLC, Hattiesburg, Mississippi An application has been submitted to the Foreign-Trade... subzone status for the facility of Channel Control Merchants, LLC, located in Hattiesburg,...

  10. Energy-efficient Joint Power Allocation and Channel Selection for D2D Communications

    Directory of Open Access Journals (Sweden)

    Guifang Ma

    2015-08-01

    Full Text Available Device-to-device (D2D communications have gained great attentions due to the potential and numerous benefits for cellular networks. However,it also brings tremendous resource allocation challenges for the sake of the constraint of battery life. Up to now, there are limited works attempt to prolong the battery life by improving the energy efficiency (EE. In this paper, we study how to perform resource allocation to increase EE in a interference limited environment under a noncooperative game model. Each D2D pair can reuse all or part of the channel resources allocated to cellular users. An energy-efficient joint power allocation and channel selection is proposed by employing the nonlinear fractional programming. We obtain the optimal power allocation and channel selection through an iterative algorithm called Dinkelbach method. Finally, the algorithm proposed in this paper is verified by simulation.

  11. Optimal Channel Selection for Spectrum-Agile Low-Power Wireless Packet Switched Networks in Unlicensed Band

    Directory of Open Access Journals (Sweden)

    Ahmad Bahai

    2008-06-01

    Full Text Available This paper addresses the problem of optimal channel selection for spectrum-agile low-powered wireless networks in unlicensed bands. The channel selection problem is formulated as a multiarmed bandit problem enabling us to derive the optimal selection rules. The model assumptions about the interfering traffic that motivates this formulation are also validated through 802.11 traffic measurements as an example of a packet switched network. Finally, the performance of the optimal dynamic channel selection is investigated through simulation. The simulation results show that the proposed algorithm consistently tracks the best channel compared to other heuristic schemes.

  12. Selective harmonic control for power converters

    DEFF Research Database (Denmark)

    Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede; Lu, Wenzhou; Danwei, Wang

    This paper proposes an Internal Model Principle (IMP) based Selective Harmonic Controller (SHC) for power converters. The proposed SHC offers an optimal control solution for power converters to mitigate power harmonics. It makes a good trade-off among cost, complexity and performance. It has high...... accuracy and fast transient response, and it is cost-effective, easy for real-time implementation, and compatible for design rules-of-thumb. An application on a three-phase PWM converter has confirmed the effectiveness of the proposed control scheme in terms of harmonic mitigation....

  13. Performance of Parallel Code Acquisition Schemes for Multicarrier CDMA over Frequency-Selective Rayleigh Fading Channels

    OpenAIRE

    Yang, L-L.; Hanzo, L

    2000-01-01

    In this contribution we investigate the issue of pseudo-noise (PN) code acquisition in a multi-carrier CDMA (MC-CDMA) system, which is suitable for high data rate transmissions. Specially, we investigate the acquisition performance of a pure parallel acquisition scheme over frequency-selective fading channels under the multiple in-phase states ($H_1$ cells) hypothesis, considering both noncoherent equal gain combining (EGC) and selection combining (SC) of the correlator outputs associated wit...

  14. Selecting RMF Controls for National Security Systems

    Energy Technology Data Exchange (ETDEWEB)

    Witzke, Edward L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    In 2014, the United States Department of Defense started tra nsitioning the way it performs risk management and accreditation of informatio n systems to a process entitled Risk Management Framework for DoD Information Technology or RMF for DoD IT. There are many more security and privacy contro ls (and control enhancements) from which to select in RMF, than there w ere in the previous Information Assurance process. This report is an attempt t o clarify the way security controls and enhancements are selected. After a brief overview and comparison of RMF for DoD I T with the previously used process, this report looks at the determination of systems as National Security Systems (NSS). Once deemed to be an NSS, this report addr esses the categorization of the information system with respect to impact level s of the various security objectives and the selection of an initial baseline o f controls. Next, the report describes tailoring the controls through the use of overl ays and scoping considerations. Finally, the report discusses organizatio n-defined values for tuning the security controls to the needs of the information system.

  15. Structural plasticity and dynamic selectivity of acid-sensing ion channel-spider toxin complexes

    Energy Technology Data Exchange (ETDEWEB)

    Baconguis, Isabelle; Gouaux, Eric [Oregon HSU

    2012-07-29

    Acid-sensing ion channels (ASICs) are voltage-independent, amiloride-sensitive channels involved in diverse physiological processes ranging from nociception to taste. Despite the importance of ASICs in physiology, we know little about the mechanism of channel activation. Here we show that psalmotoxin activates non-selective and Na+-selective currents in chicken ASIC1a at pH7.25 and 5.5, respectively. Crystal structures of ASIC1a–psalmotoxin complexes map the toxin binding site to the extracellular domain and show how toxin binding triggers an expansion of the extracellular vestibule and stabilization of the open channel pore. At pH7.25 the pore is approximately 10Å in diameter, whereas at pH5.5 the pore is largely hydrophobic and elliptical in cross-section with dimensions of approximately 5 by 7Å, consistent with a barrier mechanism for ion selectivity. These studies define mechanisms for activation of ASICs, illuminate the basis for dynamic ion selectivity and provide the blueprints for new therapeutic agents.

  16. Coulomb blockade model of permeation and selectivity in biological ion channels

    Science.gov (United States)

    Kaufman, I. Kh; McClintock, P. V. E.; Eisenberg, R. S.

    2015-08-01

    Biological ion channels are protein nanotubes embedded in, and passing through, the bilipid membranes of cells. Physiologically, they are of crucial importance in that they allow ions to pass into and out of cells, fast and efficiently, though in a highly selective way. Here we show that the conduction and selectivity of calcium/sodium ion channels can be described in terms of ionic Coulomb blockade in a simplified electrostatic and Brownian dynamics model of the channel. The Coulomb blockade phenomenon arises from the discreteness of electrical charge, the strong electrostatic interaction, and an electrostatic exclusion principle. The model predicts a periodic pattern of Ca2+ conduction versus the fixed charge Qf at the selectivity filter (conduction bands) with a period equal to the ionic charge. It thus provides provisional explanations of some observed and modelled conduction and valence selectivity phenomena, including the anomalous mole fraction effect and the calcium conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The same considerations may also be applicable to other kinds of channel, as well as to charged artificial nanopores.

  17. Performance comparison of asynchronous orthogonal multi-carrier CDMA in frequency selective channel

    OpenAIRE

    Xiang, G; Ng, TS

    1998-01-01

    Bit error rate (BER) performance of an asynchronous multi-carrier code division multiple access (MC-CDMA) system for the uplink of the mobile communication system with equal gain combining and maximum ratio combining are obtained. Given a fixed bandwidth frequency selective channel, performance of MC-CDMA is compared with that of conventional CDMA and MC-DS-CDMA in numerical results.

  18. Selection of fuel channels for Thermal Power Measurement in 700 MWe Indian PHWR by evolutionary algorithm

    International Nuclear Information System (INIS)

    Highlights: ► Thermal Power Monitoring System is used for on-line estimation of reactor bulk power and zone powers in PHWRs. ► This requires making best choice of 44 fuel channels out of 392 to be instrumented for measurement of flow and temperature. ► This constrained optimization problem is solved by Estimation of Distribution Algorithm. ► With the designed TPMS, bulk power and zone power can be predicted with an accuracy of 0.5% and 2% respectively. - Abstract: This paper presents studies on the design of Thermal Power Monitoring System (TPMS) for the forthcoming 700 MWe Indian Pressurized Heavy Water Reactor (PHWR). This reactor contains total 392 horizontal fuel channels. Each channel contains clustered natural Uranium fuel along with associated heavy water coolant placed inside a pressure tube. The coolant in different fuel channels is physically and thermally isolated from each other inside the core. It is necessary to select 44 fuel channels (out of 392) for keeping instrumentation to measure flow and temperature of coolant. The reactor is logically divided into 7 radial zones each containing certain number of fuel channels. The selection of instrumented channels is to be made such that power measured by them in terms of per unit basis represents the true zone-wise and global powers fairly accurately. This should be possible for a large number of reactor configurations that can occur because of the movement of reactivity devices in the core. Such a study is useful to make the TPMS more accurate means to measure the reactor bulk power and zone powers. The choice of 44 channels is an optimization problem in which the error in zonal and global power prediction is to be minimized. There are several constraints on the selection of instrumented channels. Therefore, a constrained combinatorial optimization problem has to be solved. An evolutionary technique based on Estimation of Distribution Algorithm (EDA) is used for this purpose. A suitable pattern of

  19. Interfacing sensory input with motor output: does the control architecture converge to a serial process along a single channel?

    Directory of Open Access Journals (Sweden)

    Cornelis Van De Kamp

    2013-05-01

    Full Text Available Modular organisation in control architecture may underlie the versatility of human motor control; but the nature of the interface relating sensory input through task-selection in the space of performance variables to control actions in the space of the elemental variables is currently unknown. Our central question is whether the control architecture converges to a serial process along a single channel? In discrete reaction time experiments, psychologists have firmly associated a serial single channel hypothesis with refractoriness and response selection (psychological refractory period. Recently, we developed a methodology and evidence identifying refractoriness in sustained control of an external single degree-of-freedom system. We hypothesise that multi-segmental whole-body control also shows refractoriness. Eight participants controlled their whole body to ensure a head marker tracked a target as fast and accurately as possible. Analysis showed enhanced delays in response to stimuli with close temporal proximity to the preceding stimulus. Consistent with our preceding work, this evidence is incompatible with control as a linear time invariant process. This evidence is consistent with a single-channel serial ballistic process within the intermittent control paradigm with an intermittent interval of around 0.5 s. A control architecture reproducing intentional human movement control must reproduce refractoriness. Intermittent control is designed to provide computational time for an online optimisation process and is appropriate for flexible adaptive control. For human motor control we suggest that parallel sensory input converges to a serial, single channel process involving planning, selection and temporal inhibition of alternative responses prior to low dimensional motor output. Such design could aid robots to reproduce the flexibility of human control.

  20. Theoretical analysis of selectivity mechanisms in molecular transport through channels and nanopores

    International Nuclear Information System (INIS)

    Selectivity is one of the most fundamental concepts in natural sciences, and it is also critically important in various technological, industrial, and medical applications. Although there are many experimental methods that allow to separate molecules, frequently they are expensive and not efficient. Recently, a new method of separation of chemical mixtures based on utilization of channels and nanopores has been proposed and successfully tested in several systems. However, mechanisms of selectivity in the molecular transport during the translocation are still not well understood. Here, we develop a simple theoretical approach to explain the origin of selectivity in molecular fluxes through channels. Our method utilizes discrete-state stochastic models that take into account all relevant chemical transitions and can be solved analytically. More specifically, we analyze channels with one and two binding sites employed for separating mixtures of two types of molecules. The effects of the symmetry and the strength of the molecular-pore interactions are examined. It is found that for one-site binding channels, the differences in the strength of interactions for two species drive the separation. At the same time, in more realistic two-site systems, the symmetry of interaction potential becomes also important. The most efficient separation is predicted when the specific binding site is located near the entrance to the nanopore. In addition, the selectivity is higher for large entrance rates into the channel. It is also found that the molecular transport is more selective for repulsive interactions than for attractive interactions. The physical-chemical origin of the observed phenomena is discussed

  1. Theoretical analysis of selectivity mechanisms in molecular transport through channels and nanopores

    Science.gov (United States)

    Agah, Shaghayegh; Pasquali, Matteo; Kolomeisky, Anatoly B.

    2015-01-01

    Selectivity is one of the most fundamental concepts in natural sciences, and it is also critically important in various technological, industrial, and medical applications. Although there are many experimental methods that allow to separate molecules, frequently they are expensive and not efficient. Recently, a new method of separation of chemical mixtures based on utilization of channels and nanopores has been proposed and successfully tested in several systems. However, mechanisms of selectivity in the molecular transport during the translocation are still not well understood. Here, we develop a simple theoretical approach to explain the origin of selectivity in molecular fluxes through channels. Our method utilizes discrete-state stochastic models that take into account all relevant chemical transitions and can be solved analytically. More specifically, we analyze channels with one and two binding sites employed for separating mixtures of two types of molecules. The effects of the symmetry and the strength of the molecular-pore interactions are examined. It is found that for one-site binding channels, the differences in the strength of interactions for two species drive the separation. At the same time, in more realistic two-site systems, the symmetry of interaction potential becomes also important. The most efficient separation is predicted when the specific binding site is located near the entrance to the nanopore. In addition, the selectivity is higher for large entrance rates into the channel. It is also found that the molecular transport is more selective for repulsive interactions than for attractive interactions. The physical-chemical origin of the observed phenomena is discussed.

  2. Energetics of discrete selectivity bands and mutation-induced transitions in the calcium-sodium ion channels family

    Science.gov (United States)

    Kaufman, I.; Luchinsky, D. G.; Tindjong, R.; McClintock, P. V. E.; Eisenberg, R. S.

    2013-11-01

    We use Brownian dynamics (BD) simulations to study the ionic conduction and valence selectivity of a generic electrostatic model of a biological ion channel as functions of the fixed charge Qf at its selectivity filter. We are thus able to reconcile the discrete calcium conduction bands recently revealed in our BD simulations, M0 (Qf=1e), M1 (3e), M2 (5e), with a set of sodium conduction bands L0 (0.5e), L1 (1.5e), thereby obtaining a completed pattern of conduction and selectivity bands vs Qf for the sodium-calcium channels family. An increase of Qf leads to an increase of calcium selectivity: L0 (sodium-selective, nonblocking channel) → M0 (nonselective channel) → L1 (sodium-selective channel with divalent block) → M1 (calcium-selective channel exhibiting the anomalous mole fraction effect). We create a consistent identification scheme where the L0 band is putatively identified with the eukaryotic sodium channel The scheme created is able to account for the experimentally observed mutation-induced transformations between nonselective channels, sodium-selective channels, and calcium-selective channels, which we interpret as transitions between different rows of the identification table. By considering the potential energy changes during permeation, we show explicitly that the multi-ion conduction bands of calcium and sodium channels arise as the result of resonant barrierless conduction. The pattern of periodic conduction bands is explained on the basis of sequential neutralization taking account of self-energy, as Qf(z,i)=ze(1/2+i), where i is the order of the band and z is the valence of the ion. Our results confirm the crucial influence of electrostatic interactions on conduction and on the Ca2+/Na+ valence selectivity of calcium and sodium ion channels. The model and results could be also applicable to biomimetic nanopores with charged walls.

  3. Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity

    Directory of Open Access Journals (Sweden)

    Aitor del Coso

    2007-11-01

    Full Text Available Multiple-input-multiple-output (MIMO techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of N wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC following a decode-and-forward (D&F strategy (i.e., regenerative forwarding, and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, 𝒞=log⁡2(W0(N. Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  4. Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity

    Directory of Open Access Journals (Sweden)

    del Coso Aitor

    2007-01-01

    Full Text Available Multiple-input-multiple-output (MIMO techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC following a decode-and-forward (D&F strategy (i.e., regenerative forwarding, and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, . Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  5. Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel

    International Nuclear Information System (INIS)

    The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high-resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential-of-mean-force profiles for sodium and chloride ions inside the transmembrane region. Our calculations reveal that the GLIC channel is open for a sodium ion to transport, but presents a 11 kcal/mol free energy barrier for a chloride ion. Our collective findings identify three distinct contributions to the observed preference for the permeant ions. First, there is a substantial contribution due to a ring of negatively charged glutamate residues (E-2 ) at the narrow intracellular end of the channel. The negative electrostatics of this region and the ability of the glutamate side chains to directly bind cations would strongly favor the passage of sodium ions while hindering translocation of chloride ions. Second, our results imply a significant hydrophobic contribution to selectivity linked to differences in the desolvation penalty for the sodium versus chloride ions in the central hydrophobic region of the pore. This hydrophobic contribution is evidenced by the large free energy barriers experienced by Cl in the middle of the pore for both GLIC and the E-2 A mutant. Finally, there is a distinct contribution arising from the overall negative electrostatics of the channel.

  6. Outage performance of Decode-and-Forward partial selection in Nakagami-m fading channels

    KAUST Repository

    Benjillali, Mustapha

    2010-01-01

    In this paper, we investigate the outage performance of Decode-and-Forward with partial selection relaying in dualhop cooperative Nakagami-m fading links. The source, based on the unique knowledge of local first hop channel state information, selects the best relay to increase the chances of successful decoding and hence the possibility of cooperation when the direct link is also available. After deriving the exact distribution of the sum of two gamma variates with the same shape parameter, the outage probability of the system-with and without the direct link-is obtained in closed-form. We also derive the ε-outage capacity in different particular cases, and the obtained results- when the channel model is reduced to a Rayleigh fading-are either new or correspond to those previously obtained in other works. Simulation results confirm the accuracy of our analysis for a large selection of system and fading parameters. © 2009 IEEE.

  7. Visual inspections of N Reactor horizontal control rod channels

    International Nuclear Information System (INIS)

    Safety surveillance is performed in horizontal control rod (HCR) channels to locate conditions which could slow or block rod travel. The findings guide the application of preventive measures to assure eventual rod motion impairment will not occur. Borescopes and, more recently, miniaturized closed circuit television (CCTV) cameras have been used for these examinations. Inspections and measurement results are documented in annual surveillance reports, however reported CCTV observations have been limited to highlights. The objective of this report is to catalogue the CCTV recordings in a format suitable for analysis and interpretation and to ease the access to any desired location by noting tape counter readings corresponding with each tube block in view. Searching file tapes for conditions in a specific areas in the past required counting blocks as they passed the camera to determine the distance from a feature like the edge of the reflector or a steam vent gap. This report adds the observations from recent rod channel inspections (1987 and 1988) to a comprehensive survey of graphite conditions in the moderator and reflector regions of the N Reactor core. When completed, the stand-by status of graphite components will be available for use in restart or decommissioning deliberations

  8. Single-Walled Carbon Nanotubes Acting as Controllable Transport Channels

    Institute of Scientific and Technical Information of China (English)

    HUANG Bo-Da; XIA Yue-Yuan; ZHAO Ming-Wen; LI Feng; LIU Xiang-Dong; JI Yan-Ju; SONG Chen; TAN Zhen-Yu; LIU Hui

    2004-01-01

    @@ The motion and equilibrium distribution of water molecules adsorbed inside neutral and negatively charged singlewalled carbon nanotubes (SWNTs) have been studied using molecular dynamics simulations (MDSs) at room temperature based on CHARMM (Chemistry at HARvard Molecular Mechanics) potential parameters. We find that water molecules have a conspicuous electropism phenomenon and regular tubule patterns inside and outside the charged tube wall. The analyses of the motion behaviour of water molecules in the radial and axial directions show that by charging the SWNT, the adsorption efficiency is greatly enhanced, and the electric field produced by the charged SWNTs prevents water molecules from flowing out of the nanotube. However, water molecules can travel through the neutral SWNT in a fluctuating manner. This indicates that by electrically charging and uncharging the SWNTs, one can control the adsorption and transport behaviour of polar molecules in SWNTs for using as a stable storage medium or long transport channels. The transport velocity can be tailored by changing the charge on the SWNTs, which may have a further application as modulatable transport channels.

  9. Meningococcal PorA/C1, a channel that combines high conductance and high selectivity.

    OpenAIRE

    Song, J.; Minetti, C A; Blake, M. S.; Colombini, M

    1999-01-01

    Class 1 porins (PorA/C1) from Neisseria meningitidis achieve both high selectivity and high conductance. The channel is highly selective (24:1 Na+ over Cl-), suggesting a highly negatively charged selectivity filter. The trimeric nature of PorA/C1 accounts for part of the enormous conductance in 200 mM NaCl (0.97nS). However, the currents that can be achieved exceed the simple infinite-sink calculation for a pore 0.7 nm in radius (estimated from nonelectrolyte permeability). The conductance i...

  10. Cation Selectivity by the CorA Mg2+ Channel Requires a Fully Hydrated Cation†

    OpenAIRE

    Moomaw, Andrea S.; Maguire, Michael E.

    2010-01-01

    The CorA Mg2+ channel is the primary uptake system in about half of all bacteria and archaea. However, the basis for its Mg2+ selectivity is unknown. Previous data suggested that CorA binds a fully hydrated Mg2+ ion, unlike other ion channels. The crystal structure of Thermotoga maritima CorA shows a homopentamer with two transmembrane segments per monomer connected by a short periplasmic loop. This highly conserved loop, 281EFMPELKWS289 in Salmonella enterica serovar Typhimurium CorA, is the...

  11. Selecting the best performing online marketing communication channels to an international start-up Eve

    OpenAIRE

    Karatsevidis, Konstantinos

    2016-01-01

    In today’s technologically advanced world online marketers are constantly faced with ever-growing challenges of running successful marketing campaigns. The problem that most of digital marketers face is the overwhelming amount of marketing tools and channels available to them. “How to select which channel to focus on?”, “Should we invest in viral marketing or social media ads?”, “What’s the next big thing in marketing?” Those are the questions marketers face every day. This Bachelor...

  12. On the structural basis for ionic selectivity among Na+, K+, and Ca2+ in the voltage-gated sodium channel.

    OpenAIRE

    Favre, I; Moczydlowski, E; Schild, L

    1996-01-01

    Voltage-sensitive sodium channels and calcium channels are homologous proteins with distinctly different selectivity for permeation of inorganic cations. This difference in function is specified by amino acid residues located within P-region segments that link presumed transmembrane elements S5 and S6 in each of four repetitive Domains I, II, III, and IV. By analyzing the selective permeability of Na+, K+, and Ca2+ in various mutants of the mu 1 rat muscle sodium channel, the results in this ...

  13. Mechanisms of atrial-selective block of Na+ channels by ranolazine: II. Insights from a mathematical model

    OpenAIRE

    Nesterenko, Vladislav V.; Zygmunt, Andrew C.; Rajamani, Sridharan; Belardinelli, Luiz; Antzelevitch, Charles

    2011-01-01

    Block of Na+ channel conductance by ranolazine displays marked atrial selectivity that is an order of magnitude higher that of other class I antiarrhythmic drugs. Here, we present a Markovian model of the Na+ channel gating, which includes activation-inactivation coupling, aimed at elucidating the mechanisms underlying this potent atrial selectivity of ranolazine. The model incorporates experimentally observed differences between atrial and ventricular Na+ channel gating, including a more neg...

  14. Controls on plan-form evolution of submarine channels

    Science.gov (United States)

    Imran, J.; Mohrig, D. C.

    2014-12-01

    Vertically aggrading sinuous channels constitute a basic building block of modern submarine fans and the greater continental slope. Interpretation of seismically imaged channels reveals a significant diversity in internal architecture, as well as important similarities and differences in the evolution of submarine channels relative to better studied rivers. Many submarine channel cross sections possess a 'gull wing' shape. Successive stacking of such channels demonstrates that systematic bank erosion is not required in order for lateral migration to occur. The lateral shift of such aggrading channels, however, is expected to be much less dynamic than in the case of terrestrial rivers. Recent high-resolution 3D seismic data from offshore Angola and an upstream segment of the Bengal Submarine Fan show intensely meandering channels that experience considerable lateral shifting during periods of active migration within submarine valleys. The cross sections of the actively migrating channels are similar to meandering river channels characterized by an outer cut-bank and inner-bank accretion. In submarine channels, the orientation of the secondary flow can be river-like or river-reverse depending on the channel gradient, cross sectional shape, and the adaptation length of the channel bend. In river channels, a single circulation cell commonly occupies the entire channel relief, redistributing the bed-load sediment across the channel, and influencing the thread of high velocity and thus the plan-form evolution of the channel. In submarine environments, the height of the circulation cell will be significantly smaller than channel relief, thus leading to development of lower relief point bars from bed-load transport. Nevertheless these "underfit" bars may play an important role in plan-form evolution of submarine channels. In rivers and submarine channels, the inclined surface accretion can be constructed via pure bed-load, suspended-load, or a combination of both transport

  15. Ultra-Wideband Channel Sounder – Design, Construction and Selected Applications

    Directory of Open Access Journals (Sweden)

    R. Zetik

    2013-06-01

    Full Text Available The paper describes construction, design, and application of a real-time ultra-wideband channel sounder. Its specific architecture allows measurements of time-variant radio propagation channels in different frequency bands. The sounder’s stimulation signal is the maximum length binary sequence. Synchronous multi-channel operation is supported by its excellent timing stability and by its low power consumption of miniature sized low temperature co-fired ceramics modules that comprise custom integrated SiGe circuits. This is a prerequisite to build a multiple-input-multiple-output sounder which is suitable for sounding even in distributed scenarios such as sensor networks. Selected application examples demonstrated the performance and possibilities of the sounder.

  16. Complexity-reduced ICI cancellation for OFDM system over doubly-selective channels

    Institute of Scientific and Technical Information of China (English)

    Xi Xiaoping; Zhang Can

    2009-01-01

    In doubly-selective fading wireless channel, the conventional orthogonal frequency division multiplexing (OFDM) receivers for inter-carrier interference (ICI) compensation require extensive computations. To obtain an effective balance between performance and complexity, the whole channel response matrix was decomposed into a sequence of submatrix, and then a novel equalizer based on minimum mean square error (MMSE) criterion was presented to combat the ICI. Furthermore, a simple ordering-based decision-feedback equalizer (DFE) was derived to exploit the temperal diversity gain offered by mobile channels. Numerical studies illustrate that although the MMSE equalizer still suffers from error floor, whereas the DFE equalizer exhibits significant performance improvement. The advantage of the proposed scheme indicates its potential applications in the future broadband wireless systems.

  17. Transmit selection for imperfect threshold-based receive MRC in Rayleigh fading channels

    KAUST Repository

    Radaydeh, Redha Mahmoud Mesleh

    2010-01-01

    The performance of multiple-antenna diversity systems in which the receiver combines signal replicas per thresholdbased maximal ratio combining (MRC) and the transmitter uses only a single antenna according to receive combined signal strength is studied. The impact of imperfect channel estimation is considered when the received signal replicas undergo independent and flat multipath fading. The analysis is applicable for arbitrary transmit antenna selection when the multiple-antenna channels experience identically distributed and non-identically distributed Rayleigh fading conditions. New closed-form expressions for the combined SNR statistics and some performance measures are presented. The system models adopted herein and the presented analytical results can be used to study the performance of different system architectures under various channel conditions when the implementation complexity is of interest. © 2009 IEEE.

  18. Selective modulation of cellular voltage dependent calcium channels by hyperbaric pressure - a suggested HPNS partial mechanism

    Directory of Open Access Journals (Sweden)

    Ben eAviner

    2014-05-01

    Full Text Available Professional deep sea divers experience motor and cognitive impairment, known as High Pressure Neurological Syndrome (HPNS, when exposed to pressures of 100 msw (1.1MPa and above, considered to be the result of synaptic transmission alteration. Previous studies have indicated modulation of presynaptic Ca2+ currents at high pressure. We directly measured for the first time pressure effects on the currents of voltage dependent Ca2+ channels (VDCCs expressed in Xenopus oocytes. Pressure selectivity augmented the current in CaV1.2 and depressed it in CaV3.2 channels. Pressure application also affected the channels' kinetics, such as ƮRise, ƮDecay. Pressure modulation of VDCCs seems to play an important role in generation of HPNS signs and symptoms.

  19. Asymptotic analysis for Nakagami-m fading channels with relay selection

    KAUST Repository

    Zhong, Caijun

    2011-06-01

    In this paper, we analyze the asymptotic outage probability performance of both decode-and-forward (DF) and amplify-and-forward (AF) relaying systems using partial relay selection and the "best" relay selection schemes for Nakagami-m fading channels. We derive their respective outage probability expressions in the asymptotic high signal-to-noise ratio (SNR) regime, from which the diversity order and coding gain are analyzed. In addition, we investigate the impact of power allocation between the source and relay terminals and derive the diversity-multiplexing tradeoff (DMT) for these relay selection systems. The theoretical findings suggest that partial relay selection can improve the diversity of the system and can achieve the same DMT as the "best" relay selection scheme under certain conditions. © 2011 IEEE.

  20. Selecting participants for listening tests of multi-channel reproduced sound

    DEFF Research Database (Denmark)

    Wickelmaier, Florian; Choisel, Sylvain

    2005-01-01

    A selection procedure was devised in order to select listeners for experiments in which their main task will be to judge multi-channel reproduced sound. 91 participants filled in a web-based questionnaire. 78 of them took part in an assessment of their hearing thresholds, their spatial hearing, and...... their verbal production abilities. The listeners displayed large individual differences in their performance. 40 subjects were selected based on the test results. The self-assessed listening habits and experience in the web questionnaire could not predict the results of the selection procedure. Further......, the hearing thresholds did not correlate with the spatial-hearing test. This leads to the conclusion that task-specific performance tests might be the preferable means of selecting a listening panel....

  1. Energetics of discrete selectivity bands and mutation-induced transitions in the calcium-sodium ion channels family

    CERN Document Server

    Kaufman, I; Tindjong, R; McClintock, P V E; Eisenberg, R S

    2013-01-01

    We use Brownian dynamics simulations to study the permeation properties of a generic electrostatic model of a biological ion channel as a function of the fixed charge Q_f at its selectivity filter. We reconcile the recently-discovered discrete calcium conduction bands M0 (Q_f=1e), M1 (3e), M2 (5e) with the set of sodium conduction bands L0 (0.5-0.7e), L1 (1.5-2e) thereby obtaining a completed pattern of conduction and selectivity bands v Q_f for the sodium-calcium channels family. An increase of Q_f leads to an increase of calcium selectivity: L0 (sodium selective, non-blocking channel) -> M0 (non-selective channel) -> L1 (sodium selective channel with divalent block) -> M1 (calcium selective channel exhibiting the anomalous mole fraction effect). We create a consistent identification scheme where the L1 band is identified with the eukaryotic (DEKA) sodium channel, and L0 (speculatively) with the bacterial NaChBac channel. The scheme created is able to account for the experimentally observed mutation-induced ...

  2. Precoded OFDM System for ICI Mitigation over Time-Frequency Selective Fading Channels

    Institute of Scientific and Technical Information of China (English)

    LONG Yi; KUANG Linling; LU Jianhua

    2009-01-01

    In orthogonal frequency-division multiplexing (OFDM) systems, the capability to support high mo-bility is greatly limited by the intercarrier interference (ICI) caused by time-frequency selective fading chan-nels. This paper presents a precoded OFDM system for ICI mitigation. A precoder is introduced to relieve the ICI by transmitting N-point composite information symbols at twice the subcarrier interval. A Ha-damard-matrix-like pilot pattern is used to recover the composite information symbols in a postprocessor at the receiver. Simulations show that, compared to the conventional self-cancellation scheme, this scheme gives much better signal-to-interference-noise ratio performance with much less overhead. Furthermore, the scheme can support twice the vehicle speed in time-frequency selective fading channels than the standard OFDM systems without ICI mitigation.

  3. Performance analysis of selective cooperation with fixed gain relays in Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-09-01

    Selecting the best relay using the maximum signal to noise ratio (SNR) among all the relays ready to cooperate saves system resources and utilizes the available bandwidth more efficiently compared to the regular all-relay cooperation. In this paper, we analyze the performance of the best relay selection scheme with fixed gain relays operating in Nakagami-. m channels. We first derive the probability density function (PDF) of upper bounded end-to-end SNR of the relay link. Using this PDF, we derive some key performance parameters for the system including average bit error probability and average channel capacity. The analytical results are verified through Monte Carlo simulations. © 2012 Elsevier B.V.

  4. A biomimetic DNA-based channel for the ligand-controlled transport of charged molecular cargo across a biological membrane

    Science.gov (United States)

    Burns, Jonathan R.; Seifert, Astrid; Fertig, Niels; Howorka, Stefan

    2016-02-01

    Biological ion channels are molecular gatekeepers that control transport across cell membranes. Recreating the functional principle of such systems and extending it beyond physiological ionic cargo is both scientifically exciting and technologically relevant to sensing or drug release. However, fabricating synthetic channels with a predictable structure remains a significant challenge. Here, we use DNA as a building material to create an atomistically determined molecular valve that can control when and which cargo is transported across a bilayer. The valve, which is made from seven concatenated DNA strands, can bind a specific ligand and, in response, undergo a nanomechanical change to open up the membrane-spanning channel. It is also able to distinguish with high selectivity the transport of small organic molecules that differ by the presence of a positively or negatively charged group. The DNA device could be used for controlled drug release and the building of synthetic cell-like or logic ionic networks.

  5. An embryo of protocells: The capsule of graphene with selective ion channels

    OpenAIRE

    Li, Zhan; Wang, Chunmei; Tian, Longlong; Bai, Jing; Yao, Huijun; Zhao, Yang; Zhang, Xin; Cao, Shiwei; Qi, Wei; Wang, Suomin; Shi, Keliang; Xu, Youwen; Mingliang, Zhang; Liu, Bo; Qiu, Hongdeng

    2015-01-01

    The synthesis of artificial cell is a route for searching the origin of protocell. Here, we create a novel cell model of graphene capsules with selective ion channels, indicating that graphene might be an embryo of protocell membrane. Firstly, we found that the highly oxidized graphene and phospholipid-graphene oxide composite would curl into capsules under a strongly acidic saturated solution of heavy metallic salt solution at low temperature. Secondly, L-amino acids exhibited higher reactiv...

  6. Performance of asynchronous orthogonal multicarrier CDMA system in frequency selective fading channel

    OpenAIRE

    Xiang, G; Ng, TS

    1999-01-01

    An asynchronous multicarrier (MC) direct-sequence (DS) code-division multiple-access (CDMA) scheme for the uplink of the mobile communication system operating in a frequency selective fading channel is analyzed. Bit error rate performance of the system with either equal-gain combining or maximum-ratio combining is obtained. Numerical results indicate that the system performs better than that of the conventional DS-CDMA system and another MC-DS-CDMA system.

  7. Applying Theoretical Approach for Predicting the Selective Calcium Channel Blockers Pharmacological Parameter by Biopartitioning Micellar Chromatography

    Institute of Scientific and Technical Information of China (English)

    WANG Su-Min; YANG Geng-Liang; LI Zhi-Wei; LIU Hai-Yan; GUO Hui-Juan

    2006-01-01

    The usefulness of biopartitioning micellar chromatography (BMC) for predicting oral drug acute toxicity and apparent bioavailability was demonstrated. A logarithmic model (an LD50 model) and the second order polynomial models (apparent bioavailability model) have been obtained using the retention data of the selective calcium channel blockers to predict pharmacological properties of compounds. The use of BMC is simple, reproducible and can provide key information about the acute toxicity and transport properties of new compounds during the drug discovery process.

  8. K(+) versus Na(+) ions in a K channel selectivity filter: a simulation study.

    OpenAIRE

    Shrivastava, Indira H.; Tieleman, D. Peter; Biggin, Philip C; Sansom, Mark S P

    2002-01-01

    Molecular dynamics simulations of a bacterial potassium channel (KcsA) embedded in a phospholipid bilayer reveal significant differences in interactions of the selectivity filter with K(+) compared with Na(+) ions. K(+) ions and water molecules within the filter undergo concerted single-file motion in which they translocate between adjacent sites within the filter on a nanosecond timescale. In contrast, Na(+) ions remain bound to sites within the filter and do not exhibit translocation on a n...

  9. Keeping active channels in their place: membrane phosphoinositides regulate TRPM channel activity in a compartment-selective manner.

    Science.gov (United States)

    Braun, Andrew P

    2012-01-01

    We have long appreciated that the controlled movement of ions and solutes across the cell surface or plasma membrane affects every aspect of cell function, ranging from membrane excitability to metabolism to secretion, and is also critical for the long-term maintenance of cell viability. Studies examining these physiological transport processes have revealed a vast array of ion channels, transporters and ATPase-driven pumps that underlie these transmembrane ionic movements and how acquired or genetic disruption of these processes are linked to disease. More recently, it has become evident that the ongoing function of intracellular organelles and subcellular compartments also depends heavily on the controlled movement of ions to establish distinct pH or ionic environments. However, limited experimental access to these subcellular domains/structures has hampered scientific progress in this area, due in large part to the difficulty of applying proven functional assays, such as patch clamp and radiotracer methodologies, to these specialized membrane locations. Using both functional and immune-labeling assays, we now know that the types and complement of channels, transporters and pumps located within intracellular membranes and organelles often differ from those present on the plasma membrane. Moreover, it appears that this differential distribution is due to the presence of discrete tags/signals present within these transport proteins that dictate their sorting/trafficking to spatially discrete membrane compartments, where they may also interact with scaffolding proteins that help maintain their localization. Such targeting signals may thus operate in a manner analogous to the way a postal code is used to direct the delivery of a letter. PMID:23151432

  10. Spreading Code Assignment Strategies for MIMO-CDMA Systems Operating in Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Claude D'Amours

    2009-01-01

    Full Text Available Code Division Multiple Access (CDMA and multiple input multiple output- (MIMO- CDMA systems suffer from multiple access interference (MAI which limits the spectral efficiency of these systems. By making these systems more power efficient, we can increase the overall spectral efficiency. This can be achieved through the use of improved modulation and coding techniques. Conventional MIMO-CDMA systems use fixed spreading code assignments. By strategically selecting the spreading codes as a function of the data to be transmitted, we can achieve coding gain and introduce additional degrees of freedom in the decision variables at the output of the matched filters. In this paper, we examine the bit error rate performance of parity bit-selected spreading and permutation spreading under different wireless channel conditions. A suboptimal detection technique based on maximum likelihood detection is proposed for these systems operating in frequency selective channels. Simulation results demonstrate that these code assignment techniques provide an improvement in performance in terms of bit error rate (BER while providing increased spectral efficiency compared to the conventional system. Moreover, the proposed strategies are more robust to channel estimation errors as well as spatial correlation.

  11. Spreading Code Assignment Strategies for MIMO-CDMA Systems Operating in Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Dahmane AdelOmar

    2009-01-01

    Full Text Available Abstract Code Division Multiple Access (CDMA and multiple input multiple output- (MIMO- CDMA systems suffer from multiple access interference (MAI which limits the spectral efficiency of these systems. By making these systems more power efficient, we can increase the overall spectral efficiency. This can be achieved through the use of improved modulation and coding techniques. Conventional MIMO-CDMA systems use fixed spreading code assignments. By strategically selecting the spreading codes as a function of the data to be transmitted, we can achieve coding gain and introduce additional degrees of freedom in the decision variables at the output of the matched filters. In this paper, we examine the bit error rate performance of parity bit-selected spreading and permutation spreading under different wireless channel conditions. A suboptimal detection technique based on maximum likelihood detection is proposed for these systems operating in frequency selective channels. Simulation results demonstrate that these code assignment techniques provide an improvement in performance in terms of bit error rate (BER while providing increased spectral efficiency compared to the conventional system. Moreover, the proposed strategies are more robust to channel estimation errors as well as spatial correlation.

  12. Potassium-selective block of barium permeation through single KcsA channels

    OpenAIRE

    Piasta, Kene N.; Theobald, Douglas L.; Miller, Christopher

    2011-01-01

    Ba2+, a doubly charged analogue of K+, specifically blocks K+ channels by virtue of electrostatic stabilization in the permeation pathway. Ba2+ block is used here as a tool to determine the equilibrium binding affinity for various monovalent cations at specific sites in the selectivity filter of a noninactivating mutant of KcsA. At high concentrations of external K+, the block-time distribution is double exponential, marking at least two Ba2+ sites in the selectivity filter, in accord with a ...

  13. Quantum Model for a Periodically Driven Selectivity Filter in K$^{+}$ Ion Channel

    OpenAIRE

    Cifuentes, A. A.; Semião, F. L.

    2013-01-01

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions thorough the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlle...

  14. Selective Kv1.3 channel blocker as therapeutic for obesity and insulin resistance

    OpenAIRE

    Upadhyay, Sanjeev Kumar; Eckel-Mahan, Kristin L.; Mirbolooki, M Reza; Tjong, Indra; Griffey, Stephen M.; Schmunk, Galina; Koehne, Amanda; Halbout, Briac; Iadonato, Shawn; Pedersen, Brian; Borrelli, Emiliana; Ping H. Wang; Mukherjee, Jogeshwar; Sassone-Corsi, Paolo; Chandy, K. George

    2013-01-01

    Obesity is a global epidemic in need of novel and safe therapeutics. We show that ShK-186, a selective blocker of the Kv1.3 potassium channel, has powerful antiobesity effects in a mouse model of diet-induced obesity. ShK-186 increases energy expenditure by activating brown adipose tissue, causes profound changes in liver metabolism and reduces obesity-induced inflammation of white adipose tissue. Our studies highlight the potential use of selective Kv1.3 blockers in the treatment of obesity ...

  15. Remotely Controlled Isomer Selective Molecular Switching.

    Science.gov (United States)

    Schendel, Verena; Borca, Bogdana; Pentegov, Ivan; Michnowicz, Tomasz; Kraft, Ulrike; Klauk, Hagen; Wahl, Peter; Schlickum, Uta; Kern, Klaus

    2016-01-13

    Nonlocal addressing-the "remote control"-of molecular switches promises more efficient processing for information technology, where fast speed of switching is essential. The surface state of the (111) facets of noble metals, a confined two-dimensional electron gas, provides a medium that enables transport of signals over large distances and hence can be used to address an entire ensemble of molecules simultaneously with a single stimulus. In this study we employ this characteristic to trigger a conformational switch in anthradithiophene (ADT) molecules by injection of hot carriers from a scanning tunneling microscope (STM) tip into the surface state of Cu(111). The carriers propagate laterally and trigger the switch in molecules at distances as far as 100 nm from the tip location. The switching process is shown to be long-ranged, fully reversible, and isomer selective, discriminating between cis and trans diastereomers, enabling maximum control. PMID:26619213

  16. Control channels with full galvanic isolation by the fiber optical communication line method

    International Nuclear Information System (INIS)

    Application of control channel with full galvanic insulation using the fiber optics communication line (FOCL) method was analyzed. The developed control systems provide full electrical insulation between the controlled facility and control center. Application of FOCL method excludes loops, occurring under conditions of coearthing of several pulse units, and background effects, occurring between control channels. The full insulation between the facility and control center assures the safety operation and high electric potential

  17. On the Classical Vibrational Coherence of Carbonyl Groups in the Selectivity Filter Backbone of KcsA Ion Channel

    OpenAIRE

    Salari, Vahid; Sajadi, Maryam; Bassereh, Hassan; Rezania, Vahid; Alaei, Mojtaba; Tuszynski, Jack

    2015-01-01

    It has been suggested that quantum coherence in the selectivity filter of ion channel may play a key role in fast conduction and selectivity of ions. However, it has not been clearly elucidated yet why classical coherence is not sufficient for this purpose. In this paper, we investigate the classical vibrational coherence between carbonyl groups oscillations in the selectivity filter of KcsA ion channels based on the data obtained from molecular dynamics simulations. Our results show that cla...

  18. Optimal Channel Selection for Spectrum-Agile Low-Power Wireless Packet Switched Networks in Unlicensed Band

    OpenAIRE

    Ahmad Bahai; Ali Motamedi

    2008-01-01

    Abstract This paper addresses the problem of optimal channel selection for spectrum-agile low-powered wireless networks in unlicensed bands. The channel selection problem is formulated as a multiarmed bandit problem enabling us to derive the optimal selection rules. The model assumptions about the interfering traffic that motivates this formulation are also validated through 802.11 traffic measurements as an example of a packet switched network. Finally, the performance of the optimal dynamic...

  19. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate.

    Science.gov (United States)

    Ivanov, Vadim; Ivanova, Svetlana; Kalinovsky, Tatiana; Niedzwiecki, Aleksandra; Rath, Matthias

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition to the side effects mentioned above by different channel blockers, these drugs can cause arterial wall damage, thereby contributing to vascular wall structure destabilization and promoting events facilitating rupture of plaques. Collagen synthesis is regulated by ascorbic acid, which is also essential for its optimum structure as a cofactor in lysine and proline hydroxylation, a precondition for optimum crosslinking of collagen and elastin. Therefore, the main objective in this study was to evaluate effects of various types of channel blockers on intracellular accumulation and cellular functions of ascorbate, specifically in relation to formation and extracellular deposition of major collagen types relevant for vascular function. Effects of select Na- and Ca- channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay. All channel blockers tested demonstrated inhibitory effects on collagen type I deposition to the ECM by fibroblasts, each to a different degree. Ascorbic acid significantly increased collagen I ECM deposition. Nifedipine (50 µM), a representative of channel blockers tested, significantly reduced ascorbic acid and ascorbyl palmitate-dependent ECM deposition of collagen type l and collagen type lV by cultured aortic smooth muscle cells. In addition, nifedipine (50 µM) significantly reduced ascorbate-dependent collagen type l and type lV synthesis by cultured aortic smooth

  20. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate

    Science.gov (United States)

    Ivanov, Vadim; Ivanova, Svetlana; Kalinovsky, Tatiana; Niedzwiecki, Aleksandra; Rath, Matthias

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition to the side effects mentioned above by different channel blockers, these drugs can cause arterial wall damage, thereby contributing to vascular wall structure destabilization and promoting events facilitating rupture of plaques. Collagen synthesis is regulated by ascorbic acid, which is also essential for its optimum structure as a cofactor in lysine and proline hydroxylation, a precondition for optimum crosslinking of collagen and elastin. Therefore, the main objective in this study was to evaluate effects of various types of channel blockers on intracellular accumulation and cellular functions of ascorbate, specifically in relation to formation and extracellular deposition of major collagen types relevant for vascular function. Effects of select Na- and Ca- channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay. All channel blockers tested demonstrated inhibitory effects on collagen type I deposition to the ECM by fibroblasts, each to a different degree. Ascorbic acid significantly increased collagen I ECM deposition. Nifedipine (50 µM), a representative of channel blockers tested, significantly reduced ascorbic acid and ascorbyl palmitate-dependent ECM deposition of collagen type l and collagen type lV by cultured aortic smooth muscle cells. In addition, nifedipine (50 µM) significantly reduced ascorbate-dependent collagen type l and type lV synthesis by cultured aortic smooth

  1. On Communication over Unknown Sparse Frequency-Selective Block-Fading Channels

    CERN Document Server

    Kannu, Arun Pachai

    2010-01-01

    The problem of reliable communication over unknown frequency-selective block-fading channels with sparse impulse responses is considered. In particular, discrete-time channels of length $L$ and sparsity $S\\leq L$, whose support and coefficients remain fixed over blocks of $N>L$ channel uses, but change independently from block to block, are considered in the high-SNR regime. Here, both the support and the coefficient realizations are apriori unknown. Assuming that the non-zero coefficients and noise are both Gaussian, it is first shown that the ergodic noncoherent channel capacity has pre-log factor $1-\\frac{S}{N}$ for any $L$. Next a pilot-aided transmission (PAT) scheme and noncoherent decoder are proposed which are capable of communicating with arbitrarily small error probability using only $S$ pilots per fading block. Furthermore, the achievable rate of this scheme is shown to have the optimal pre-log factor, i.e., $1-\\frac{S}{N}$. The proposed approach, which requires only $S$ pilots, can be contrasted w...

  2. Engineering Highly Potent and Selective Microproteins against Nav1.7 Sodium Channel for Treatment of Pain.

    Science.gov (United States)

    Shcherbatko, Anatoly; Rossi, Andrea; Foletti, Davide; Zhu, Guoyun; Bogin, Oren; Galindo Casas, Meritxell; Rickert, Mathias; Hasa-Moreno, Adela; Bartsevich, Victor; Crameri, Andreas; Steiner, Alexander R; Henningsen, Robert; Gill, Avinash; Pons, Jaume; Shelton, David L; Rajpal, Arvind; Strop, Pavel

    2016-07-01

    The prominent role of voltage-gated sodium channel 1.7 (Nav1.7) in nociception was revealed by remarkable human clinical and genetic evidence. Development of potent and subtype-selective inhibitors of this ion channel is crucial for obtaining therapeutically useful analgesic compounds. Microproteins isolated from animal venoms have been identified as promising therapeutic leads for ion channels, because they naturally evolved to be potent ion channel blockers. Here, we report the engineering of highly potent and selective inhibitors of the Nav1.7 channel based on tarantula ceratotoxin-1 (CcoTx1). We utilized a combination of directed evolution, saturation mutagenesis, chemical modification, and rational drug design to obtain higher potency and selectivity to the Nav1.7 channel. The resulting microproteins are highly potent (IC50 to Nav1.7 of 2.5 nm) and selective. We achieved 80- and 20-fold selectivity over the closely related Nav1.2 and Nav1.6 channels, respectively, and the IC50 on skeletal (Nav1.4) and cardiac (Nav1.5) sodium channels is above 3000 nm The lead molecules have the potential for future clinical development as novel therapeutics in the treatment of pain. PMID:27129258

  3. Design and Implementation of an Underlay Control Channel for Cognitive Radios

    Energy Technology Data Exchange (ETDEWEB)

    Daryl Wasden; Hussein Moradi; Behrouz Farhang-Boroujeny

    2012-11-01

    Implementation of any cognitive radio network requires an effective control channel that can operate under various modes of activity from the primary users. This paper reports the design and implementation of a filter bank multicarrier spread spectrum (FBMC-SS) system for use as the control channel in cognitive radio networks. The proposed design is based on a filtered multitone (FMT) implementation. Carrier and timing acquisition and tracking methods as well as a blind channel estimation method are developed for the proposed control channel. We also report an implementation of the proposed FBMC-SS system on a hardware platform; a FlexRIO FPGA module from National Instruments.

  4. Robust Control for Lateral and Longitudinal Channels of Small-Scale Unmanned Helicopters

    Directory of Open Access Journals (Sweden)

    Bao Feng

    2015-01-01

    Full Text Available Lateral and longitudinal channels are two closely related channels whose control stability influences flight performance of small-scale unmanned helicopters directly. This paper presents a robust control approach for lateral and longitudinal channels in the presence of parameter uncertainties and exogenous disturbances. The proposed control approach is performed by two steps. First, by performing system identification in frequency domain, system model of lateral and longitudinal channels can be accurately identified. Then, a robust H∞ state feedback controller is designed to stabilize the helicopter in lateral and longitudinal channels simultaneously under extraneous disturbances situation. The proposed approach takes advantages that it reduces order of the controller by preestimating some parameters (like flapping angles without sacrificing control accuracy. Numerical results show the reliability and effectiveness of the proposed method.

  5. Efficient Control Channel Resource Allocation for VoIP in OFDMA-Based Packet Radio Networks

    Directory of Open Access Journals (Sweden)

    Fan Yong

    2011-01-01

    Full Text Available We propose an efficient control channel resource allocation approach to enhance the performance of voice-over-IP (VoIP in orthogonal frequency division multiple access- (OFDMA- based next generation mobile communication systems. As the long-term evolution (LTE of universal terrestrial radio access network (UTRAN, evolved UTRAN (E-UTRAN is the first OFDMA-based packet radio network and thus selected in this paper as an application example. Our proposed physical downlink control channel (PDCCH resource allocation approach for E-UTRAN is composed of bidirectional power control, inner loop link adaptation (ILLA, and outer loop link adaptation (OLLA algorithms. Its effectiveness is validated through large-scale radio system level simulations, and simulation results confirm that VoIP capacity with dynamic scheduling can be further enhanced with this PDCCH resource allocation approach. Moreover, the VoIP performance requirements for international mobile telecommunications-advanced (IMT-Advanced radio interface technologies can be met with dynamic scheduling together with proposed PDCCH resource allocation. Besides E-UTRAN, this approach can be introduced to other OFDMA-based mobile communication systems for VoIP performance enhancement as well.

  6. Control of Energy Density inside a Disordered Medium by Coupling to Open or Closed Channels.

    Science.gov (United States)

    Sarma, Raktim; Yamilov, Alexey G; Petrenko, Sasha; Bromberg, Yaron; Cao, Hui

    2016-08-19

    We demonstrate experimentally the efficient control of light intensity distribution inside a random scattering system. The adaptive wave front shaping technique is applied to a silicon waveguide containing scattering nanostructures, and the on-chip coupling scheme enables access to all input spatial modes. By selectively coupling the incident light to the open or closed channels of the disordered system, we not only vary the total energy stored inside the system by a factor of 7.4, but also change the energy density distribution from an exponential decay to a linear decay and to a profile peaked near the center. This work provides an on-chip platform for controlling light-matter interactions in turbid media. PMID:27588875

  7. Control of energy density inside disordered medium by coupling to open or closed channels

    CERN Document Server

    Sarma, Raktim; Petrenko, Sasha; Bromberg, Yaron; Cao, Hui

    2016-01-01

    We demonstrate experimentally an efficient control of light intensity distribution inside a random scattering system. The adaptive wavefront shaping technique is applied to a silicon waveguide containing scattering nanostructures, and the on-chip coupling scheme enables access to all input spatial modes. By selectively coupling the incident light to open or closed channels of the disordered system, we not only vary the total energy stored inside the system by 7.4 times, but also change the energy density distribution from an exponential decay to a linear decay and to a profile peaked near the center. This work provides an on-chip platform for controlling light-matter interactions in turbid media.

  8. Adaptive Modulation with Best User Selection over Non-Identical Nakagami Fading Channels

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  9. ERGODIC CAPACITY FORMULA OF MIMO-OFDM SYSTEMS UNDER CORRELATED FREQUENCY SELECTIVE RAYLEIGH FADING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An explicit formula for the ergodic capacity of Orthogonal Frequency Division Multiplexing (OFDM)-based Multiple-Input Multiple-Output (MIMO) systems under correlated frequency selective Rayleigh channels is derived, by simplifying the channel response matrix in frequency domain into the so-called Kronecker model composed of three kinds of correlations, i.e. multipath tap gain correlation and spatial fading correlations at both transmitter and receiver. The derived formula is very simple and convenient for one to estimate the effects of all three kinds of correlations on MIMO-OFDM capacity. If taps are independent, there is a very simple expression for the ergodic capacity. In case of tap correlation, the capacity formula could be further given in an integral expression. The validity of the new formula is verified and the effects of correlations, delay spread as well as the number of subcarriers on the ergodic capacity are evaluated via Monte Carlo simulations.

  10. Cell volume and membrane stretch independently control K+ channel activity

    DEFF Research Database (Denmark)

    Bomholtz, Sofia Hammami; Willumsen, Niels J; Olsen, Hervør L; Morera, Francisco J; Latorre, Ramón; Klaerke, Dan A

    . To test this hypothesis we have studied the regulation of KCNQ1 and BK channels after expression in Xenopus oocytes. Results from cell-attached patch clamp studies (approximately 50 microm(2) macropatches) in oocytes expressing BK channels demonstrate that the macroscopic volume-insensitive BK...... current increases with increasing negative hydrostatic pressure (suction) applied to the pipette. Thus, at a pipette pressure of -5.0 +/- 0.1 mmHg the increase amounted to 381 +/- 146% (mean +/- S.E.M., n = 6, P < 0.025). In contrast, in oocytes expressing the strongly volume-sensitive KCNQ1 channel, the...

  11. Robust fetal QRS detection from noninvasive abdominal electrocardiogram based on channel selection and simultaneous multichannel processing.

    Science.gov (United States)

    Ghaffari, Ali; Mollakazemi, Mohammad Javad; Atyabi, Seyyed Abbas; Niknazar, Mohammad

    2015-12-01

    The purpose of this study is to provide a new method for detecting fetal QRS complexes from non-invasive fetal electrocardiogram (fECG) signal. Despite most of the current fECG processing methods which are based on separation of fECG from maternal ECG (mECG), in this study, fetal heart rate (FHR) can be extracted with high accuracy without separation of fECG from mECG. Furthermore, in this new approach thoracic channels are not necessary. These two aspects have reduced the required computational operations. Consequently, the proposed approach can be efficiently applied to different real-time healthcare and medical devices. In this work, a new method is presented for selecting the best channel which carries strongest fECG. Each channel is scored based on two criteria of noise distribution and good fetal heartbeat visibility. Another important aspect of this study is the simultaneous and combinatorial use of available fECG channels via the priority given by their scores. A combination of geometric features and wavelet-based techniques was adopted to extract FHR. Based on fetal geometric features, fECG signals were divided into three categories, and different strategies were employed to analyze each category. The method was validated using three datasets including Noninvasive fetal ECG database, DaISy and PhysioNet/Computing in Cardiology Challenge 2013. Finally, the obtained results were compared with other studies. The adopted strategies such as multi-resolution analysis, not separating fECG and mECG, intelligent channels scoring and using them simultaneously are the factors that caused the promising performance of the method. PMID:26462679

  12. Rough-Wall Channel Analysis Using Suboptimal Control Theory

    Science.gov (United States)

    Flores, O.; Jimenez, J.; Tenpleton, J.

    2003-01-01

    The original aim of this work was to shed some light on the physics of turbulence over rough walls using large-eddy simulations and the suboptimal-control wall boundary conditions introduced by Nicoud et al. It was hoped that, if that algorithm was used to fit the mean velocity profile of the simulations to that of a rough-walled channel, instead of to a smooth one, the wall stresses introduced by the control algorithm would give some indication of what aspects of rough walls are most responsible for the modification of the flow in real turbulence. It was similarly expected that the structure of the resulting velocity fluctuations would share some of the characteristics of rough-walled flows, thus again suggesting what is intrinsic and what is accidental in the effect of geometric wall roughness. A secondary goal was to study the effect of 'unphysical' boundary conditions on the outside flow by observing how a relatively major change of the target velocity profile, and therefore presumably of the applied wall stresses, modifies properties such as the dominant length scales of the velocity fluctuations away from the wall. As will be seen below, this secondary goal grew more important during the course of the study, which was carried out during a short summer visit of the first two authors to the CTR. It became clear that there are open questions about the way in which the control algorithm models the boundary conditions, even for smooth walls, and that these questions make the physical interpretation of the results difficult. Considerable more work in that area seems to be needed before even relatively advanced large-eddy simulations, such as these, can be used to draw conclusions about the physics of wall-bounded turbulent flows. The numerical method is the same as in Nicoud et al. The modifications introduced in the original code are briefly described in section 2, but the original paper should be consulted for a full description of the algorithm. The results are

  13. Phosphatidylinositol 4,5-bisphosphate alters pharmacological selectivity for epilepsy-causing KCNQ potassium channels

    Science.gov (United States)

    Zhou, Pingzheng; Yu, Haibo; Gu, Min; Nan, Fa-jun; Gao, Zhaobing; Li, Min

    2013-01-01

    Pharmacological augmentation of neuronal KCNQ muscarinic (M) currents by drugs such as retigabine (RTG) represents a first-in-class therapeutic to treat certain hyperexcitatory diseases by dampening neuronal firing. Whereas all five potassium channel subtypes (KCNQ1–KCNQ5) are found in the nervous system, KCNQ2 and KCNQ3 are the primary players that mediate M currents. We investigated the plasticity of subtype selectivity by two M current effective drugs, retigabine and zinc pyrithione (ZnPy). Retigabine is more effective on KCNQ3 than KCNQ2, whereas ZnPy is more effective on KCNQ2 with no detectable effect on KCNQ3. In neurons, activation of muscarinic receptor signaling desensitizes effects by retigabine but not ZnPy. Importantly, reduction of phosphatidylinositol 4,5-bisphosphate (PIP2) causes KCNQ3 to become sensitive to ZnPy but lose sensitivity to retigabine. The dynamic shift of pharmacological selectivity caused by PIP2 may be induced orthogonally by voltage-sensitive phosphatase, or conversely, abolished by mutating a PIP2 site within the S4–S5 linker of KCNQ3. Therefore, whereas drug-channel binding is a prerequisite, the drug selectivity on M current is dynamic and may be regulated by receptor signaling pathways via PIP2. PMID:23650395

  14. Putative resolution of the EEEE selectivity paradox in L-type Ca2+ and bacterial Na+ biological ion channels

    Science.gov (United States)

    Kaufman, I. Kh; Luchinsky, D. G.; Gibby, W. A. T.; McClintock, P. V. E.; Eisenberg, R. S.

    2016-05-01

    The highly selective permeation of ions through biological ion channels can be described and explained in terms of fluctuational dynamics under the influence of powerful electrostatic forces. Hence valence selectivity, e.g. between Ca2+ and Na+ in calcium and sodium channels, can be described in terms of ionic Coulomb blockade, which gives rise to distinct conduction bands and stop-bands as the fixed negative charge Q f at the selectivity filter of the channel is varied. This picture accounts successfully for a wide range of conduction phenomena in a diversity of ion channels. A disturbing anomaly, however, is that what appears to be the same electrostatic charge and structure (the so-called EEEE motif) seems to select Na+ conduction in bacterial channels but Ca2+ conduction in mammalian channels. As a possible resolution of this paradox it is hypothesised that an additional charged protein residue on the permeation path of the mammalian channel increases |{{Q}f}| by e, thereby altering the selectivity from Na+ to Ca2+. Experiments are proposed that will enable the hypothesis to be tested.

  15. Dynamics of ions in the selectivity filter of the KcsA channel

    OpenAIRE

    Cosseddu, Salvatore M.; Khovanov, I. A.; Allen, Michael P.; Rodger, P. Mark; Luchinsky, Dmitrii G.; McClintock, Peter V. E.

    2013-01-01

    The statistical and dynamical properties of ions in the selectivity filter of the KcsA ion channel are considered on the basis of molecular dynamics (MD) simulations of the KcsA protein embedded in a lipid membrane surrounded by an ionic solution. A new approach to the derivation of a Brownian dynamics (BD) model of ion permeation through the filter is discussed, based on unbiased MD simulations. It is shown that depending on additional assumptions, ion's dynamics can be described either by u...

  16. Atrial-Selective Sodium Channel Block Strategy to Suppress Atrial Fibrillation: Ranolazine versus Propafenone

    OpenAIRE

    Burashnikov, Alexander; Belardinelli, Luiz; Antzelevitch, Charles

    2012-01-01

    Ranolazine has been shown to produce atrial-selective depression of sodium channel-dependent parameters and suppress atrial fibrillation (AF) in a variety of experimental models. The present study contrasts the effects of ranolazine and those of a clinically used anti-AF class IC agent, propafenone. Electrophysiological and anti-AF effects of propafenone and ranolazine were compared at clinically relevant concentrations (i.e., 0.3–1.5 and 1–10 μM, respectively) in canine isolated coronary-per...

  17. Improving Performance of Wi-Fi by Compact MIMO Systems by using Gama Frequency-Selective Fading Channels

    OpenAIRE

    Sudesh Gupta; Rajesh Nema; Puran Gour

    2011-01-01

    In this paper we propose a compact MIMO system in frequency-selective fading channels which improves the performance of Wireless Media. A MIMO beam forming system model with mutual coupling and matching network is proposed to cope with frequency-selective fading channels. The overall system proposed transfer matrix is derived using Z-parameter method. The system using the transform matrix which accepts the relay and the delay matrix for the computation. Then apply the diversity criteria by wh...

  18. Design and performance of two-channel EUV multilayer mirrors with enhanced spectral selectivity

    Science.gov (United States)

    Hecquet, Christophe; Delmotte, Franck; Ravet-Krill, Marie-Françoise; de Rossi, Sébastien; Jérome, Arnaud; Bridou, Françoise; Varnière, Françoise; Meltchakov, Evgueni; Auchère, Frédéric; Giglia, Angelo; Mahne, Nicola; Nanaronne, Stefano

    2009-05-01

    In this paper, we present a study on two-channel multilayer mirrors which can operate at two wavelengths in Extreme Ultraviolet (EUV) spectral range. We propose a new method to design two-channel EUV multilayer mirrors with enhanced spectral selectivity. The mirror structure is a stack of two periodic multilayers separated by a buffer layer. We have defined the main parameters which allow adjustment of the distance between different order Bragg’s peak and of wavelength positions of reflectivity minima. Two mirrors have been designed and deposited for solar EUV telescope applications by using this method. The first mirror reflects Fe IX-X line (17.1 nm) and Fe XVI (33.5 nm) lines with attenuation of the He II line (30.4 nm). The second mirror reflects Fe IX-X and He II lines with attenuation of Fe XV (28.4 nm) and Fe XVI lines. Measurements with synchrotron radiation source confirm that, in both cases, for these mirrors, we are able to adjust reflectivity maxima (Bragg peak position) and minima. Such multilayers offer new possibilities for compact design of multi-wavelength EUV telescopes and/or for high spectral selectivity.

  19. An embryo of protocells: The capsule of graphene with selective ion channels

    Science.gov (United States)

    Li, Zhan; Wang, Chunmei; Tian, Longlong; Bai, Jing; Yao, Huijun; Zhao, Yang; Zhang, Xin; Cao, Shiwei; Qi, Wei; Wang, Suomin; Shi, Keliang; Xu, Youwen; Mingliang, Zhang; Liu, Bo; Qiu, Hongdeng; Liu, Jie; Wu, Wangsuo; Wang, Xiaoli; Wenzhen, An

    2015-05-01

    The synthesis of artificial cell is a route for searching the origin of protocell. Here, we create a novel cell model of graphene capsules with selective ion channels, indicating that graphene might be an embryo of protocell membrane. Firstly, we found that the highly oxidized graphene and phospholipid-graphene oxide composite would curl into capsules under a strongly acidic saturated solution of heavy metallic salt solution at low temperature. Secondly, L-amino acids exhibited higher reactivity than D-amino acids on graphene oxides to form peptides, and the formed peptides in the influence of graphene would be transformed into a secondary structure, promoting the formation of left-handed proteins. Lastly, monolayer nanoporous graphene, prepared by unfocused 84Kr25+, has a high selectivity for permeation of the monovalent metal ions ( Rb+ > K+ > Cs+ > Na+ > Li+, based on permeation concentration), but does not allow Cl- go through. It is similar to K+ channels, which would cause an influx of K+ into capsule of graphene with the increase of pH in the primitive ocean, creating a suitable inner condition for the origin of life. Therefore, we built a model cell of graphene, which would provide a route for reproducing the origin of life.

  20. Stochastic Control of Event-Driven Feedback in Multi-Antenna Interference Channels

    OpenAIRE

    Huang, Kaibin; Lau, Vincent K. N.; Kim, Dongku

    2010-01-01

    Spatial interference avoidance is a simple and effective way of mitigating interference in multi-antenna wireless networks. The deployment of this technique requires channel-state information (CSI) feedback from each receiver to all interferers, resulting in substantial network overhead. To address this issue, this paper proposes the method of distributive control that intelligently allocates CSI bits over multiple feedback links and adapts feedback to channel dynamics. For symmetric channel ...

  1. Heat Transfer Enhancement by Flow Control in a Rectangular Horizontal Channel

    OpenAIRE

    Ghazali Mebarki; Samir Rahal; Abdelhek Hamza

    2013-01-01

    Laminar fluid flows and heat transfers, by forced convection, in a rectangular horizontal channel, have been numerically investigated. Three blocks, simulating electronic components, have been attached to the channel bottom wall. In order to control the flow and enhance the heat transfer rate, a rectangular cross section bar, acting as a vortex generator, has been attached to the channel top wall. The Navier-Stokes and energy equations are solved using FLUENT. Velocity and temperature fields ...

  2. Adaptive Four-Channel Neuro-Fuzzy Control of a Master-Slave Robot

    Directory of Open Access Journals (Sweden)

    Watcharin Po-Ngaen

    2013-03-01

    Full Text Available In bilateral control of tele‐manipulation based on a conventional approach, there are deficiencies in stability robustness and manoeuvrability against variations in the dynamics of the master input device and the task environment. In this study, an adaptive four‐channel neuro‐fuzzy bilateral control scheme is proposed. To evaluate whether the proposed algorithm is a suitable technique for improving the robustness and manoeuvrability of tele‐robot implementation, four‐channel neuro‐fuzzy and classical bilateral control frameworks have been investigated in a simulation experiment. Distinct bilateral control schemes in the form of four‐channel intelligent control and the classic form of position–force and position‐position have been implemented and compared using a one degree of freedom (DOF master‐slave system. The experimental results show that the application of a four‐channel neuro‐fuzzy control strategy effectively improves the overall performance.

  3. Transmit selection algorithms for imperfect threshold-based receive MRC in the presence of co-channel interference

    KAUST Repository

    Radaydeh, Redha Mahmoud Mesleh

    2010-01-01

    The performance of transmit antenna selection for threshold-based maximal ratio combining (MRC) diversity receivers in the presence of multiple co-channel interfering signals is studied. The impact of imperfect channel estimation of desired user signals is considered, and the effect of phase and time misalignments between desired and undesired signals is incorporated in the analysis. Precise formulation for Nakagami-m faded interfering signals is presented. The analysis is applicable for arbitrary transmit antenna selection, which is based on the receiver combined signal-to-noise ratios (SNRs) or combined signal-to-interference-plus-noise ratios (SINRs) for different transmit channels. New expressions for the distribution of combined SINR and outage probability performance are derived considering SNR-based as well as SINR-based selection algorithms. The results can be used to study the performance of different system architectures under various channel conditions when the implementation complexity is of interest. ©2010 IEEE.

  4. Aperiodic Linear Networked Control Considering Variable Channel Delays: Application to Robots Coordination (+ supplementary file)

    NARCIS (Netherlands)

    Santos, C.; Espinosa, F.; Santiso, E.; Mazo, M.

    2015-01-01

    One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is th

  5. Selectivity of calcium channels in rat uterine smooth muscle: interactions between sodium, calcium and barium ions.

    Science.gov (United States)

    Jmari, K; Mironneau, C; Mironneau, J

    1987-03-01

    1. Action potentials and membrane currents were recorded by means of a double sucrose-gap technique from Cs-loaded strips from pregnant rats superfused in Ca-free EGTA-containing solutions. 2. When external Ca was reduced below 1 microM in the presence of 1 mM-EGTA, step depolarizations from a holding potential close to the normal resting potential produced tetrodotoxin-resistant inward currents. These currents were suppressed after removal of external Na and blocked by a variety of Ca-channel blockers such as Mn, Co, Ni and nifedipine. 3. Inactivation of the inward Na current was studied using a double-pulse protocol. The degree of inactivation of the Na current was almost maximal for depolarizations of +50 mV. Application of stronger depolarizations did not significantly increase it and had no effect on recovery from inactivation. Similarly, increasing the duration of the conditioning pulse from 30 to 250 ms had no further effect on both amplitude and kinetics of the Na current. These results suggest that the Na current inactivation reflects a pure voltage-dependent mechanism. 4. The effects of external Ca were studied over a 10(9)-fold range in concentration. When external Ca was gradually increased from 1 nM to 1 microM, the inward Na current was reduced and finally abolished. As the external Ca was increased over 0.5 mM, inward current reappeared and increased as Ca became the charge carrier. 5. When Na was the charge carrier, external Ca was the most effective divalent cation in blocking the Ca channel with a half-blockage concentration of 0.1 microM. Addition of millimolar concentrations of Ca and Sr also reduced the Ba current while adding Ba to Ca-containing solution produced no increase in current. 6. Membrane currents in solutions containing both Ba and Ca ions were less than in solutions containing either Ca or Ba at the same concentration, suggesting that Ca channels are single-file multi-ion pores. 7. We conclude that the selectivity of uterine Ca

  6. Identification of ML204, a Novel Potent Antagonist That Selectively Modulates Native TRPC4/C5 Ion Channels*

    Science.gov (United States)

    Miller, Melissa; Shi, Jie; Zhu, Yingmin; Kustov, Maksym; Tian, Jin-bin; Stevens, Amy; Wu, Meng; Xu, Jia; Long, Shunyou; Yang, Pu; Zholos, Alexander V.; Salovich, James M.; Weaver, C. David; Hopkins, Corey R.; Lindsley, Craig W.; McManus, Owen; Li, Min; Zhu, Michael X.

    2011-01-01

    Transient receptor potential canonical (TRPC) channels are Ca2+-permeable nonselective cation channels implicated in diverse physiological functions, including smooth muscle contractility and synaptic transmission. However, lack of potent selective pharmacological inhibitors for TRPC channels has limited delineation of the roles of these channels in physiological systems. Here we report the identification and characterization of ML204 as a novel, potent, and selective TRPC4 channel inhibitor. A high throughput fluorescent screen of 305,000 compounds of the Molecular Libraries Small Molecule Repository was performed for inhibitors that blocked intracellular Ca2+ rise in response to stimulation of mouse TRPC4β by μ-opioid receptors. ML204 inhibited TRPC4β-mediated intracellular Ca2+ rise with an IC50 value of 0.96 μm and exhibited 19-fold selectivity against muscarinic receptor-coupled TRPC6 channel activation. In whole-cell patch clamp recordings, ML204 blocked TRPC4β currents activated through either μ-opioid receptor stimulation or intracellular dialysis of guanosine 5′-3-O-(thio)triphosphate (GTPγS), suggesting a direct interaction of ML204 with TRPC4 channels rather than any interference with the signal transduction pathways. Selectivity studies showed no appreciable block by 10–20 μm ML204 of TRPV1, TRPV3, TRPA1, and TRPM8, as well as KCNQ2 and native voltage-gated sodium, potassium, and calcium channels in mouse dorsal root ganglion neurons. In isolated guinea pig ileal myocytes, ML204 blocked muscarinic cation currents activated by bath application of carbachol or intracellular infusion of GTPγS, demonstrating its effectiveness on native TRPC4 currents. Therefore, ML204 represents an excellent novel tool for investigation of TRPC4 channel function and may facilitate the development of therapeutics targeted to TRPC4. PMID:21795696

  7. A multi-channel humidity control system based on LabVIEW

    International Nuclear Information System (INIS)

    A real time multi-channel humidity control system was designed based on LabVIEW, using the dry air branch of BESⅢ drying system. The hardware of this control system consist of mini humidity and temperature sensors, intelligent collection module, switch quantity controller and electromagnetic valves. The humidity can be controlled at arbitrary value from air humidity to 3% with accuracy better than 2%. Multi microenvironment with different humidity can be easily controlled and monitored in real time by this system. It can also be extended to hybrid control of multi channel humidity and temperature. (authors)

  8. Quality Control in Child Care Staff Selection

    Science.gov (United States)

    Crow, Merwin R.

    1975-01-01

    This paper focuses on the process of staff selection of child care staff at a residential treatment center for children, ages 8-16. Phases of candidate selection, an "open-door" interview procedure, the orientation of hired candidates and the agency's philosophy, procedures and practices are discussed. (GO)

  9. Calcineurin Controls Voltage-Dependent-Inactivation (VDI) of the Normal and Timothy Cardiac Channels.

    Science.gov (United States)

    Cohen-Kutner, Moshe; Yahalom, Yfat; Trus, Michael; Atlas, Daphne

    2012-01-01

    Ca(2+)-entry in the heart is tightly controlled by Cav1.2 inactivation, which involves Ca(2+)-dependent inactivation (CDI) and voltage-dependent inactivation (VDI) components. Timothy syndrome, a subtype-form of congenital long-QT syndrome, results from a nearly complete elimination of VDI by the G406R mutation in the α(1)1.2 subunit of Cav1.2. Here, we show that a single (A1929P) or a double mutation (H1926A-H1927A) within the CaN-binding site at the human C-terminal tail of α(1)1.2, accelerate the inactivation rate and enhances VDI of both wt and Timothy channels. These results identify the CaN-binding site as the long-sought VDI-regulatory motif of the cardiac channel. The substantial increase in VDI and the accelerated inactivation caused by the selective inhibitors of CaN, cyclosporine A and FK-506, which act at the same CaN-binding site, further support this conclusion. A reversal of enhanced-sympathetic tone by VDI-enhancing CaN inhibitors could be beneficial for improving Timothy syndrome complications such as long-QT and autism. PMID:22511998

  10. Equivalence of Linear MMSE Detection in DS-CDMA and MC-CDMA Systems over Time and Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    Tamer A. Kadous

    2003-01-01

    Full Text Available The goal of this paper is to compare the performance of the linear minimum mean square error (MMSE detector for a class of code division multiple access (CDMA systems in time and frequency selective channels. Specifically, we consider direct sequence (DS-CDMA, multicarrier (MC-CDMA, and the MC-DS-CDMA systems. Two key tools are used in our development. First, a general time-frequency framework that includes the different CDMA systems as special cases. Second, the duality between time and frequency domains that is used to derive equivalences between the different CDMA systems operating over purely frequency selective and purely time selective channels. We then combine the insights obtained from these special cases to assess the performance of CDMA systems over time and frequency selective channels. We provide sufficient conditions for the codes employed by the CDMA systems for the equivalences to hold. Numerical results are presented to illustrate the results.

  11. A Fairness-Based Access Control Scheme to Optimize IPTV Fast Channel Changing

    Directory of Open Access Journals (Sweden)

    Junyu Lai

    2014-01-01

    Full Text Available IPTV services are typically featured with a longer channel changing delay compared to the conventional TV systems. The major contributor to this lies in the time spent on intraframe (I-frame acquisition during channel changing. Currently, most widely adopted fast channel changing (FCC methods rely on promptly transmitting to the client (conducting the channel changing a retained I-frame of the targeted channel as a separate unicasting stream. However, this I-frame acceleration mechanism has an inherent scalability problem due to the explosions of channel changing requests during commercial breaks. In this paper, we propose a fairness-based admission control (FAC scheme for the original I-frame acceleration mechanism to enhance its scalability by decreasing the bandwidth demands. Based on the channel changing history of every client, the FAC scheme can intelligently decide whether or not to conduct the I-frame acceleration for each channel change request. Comprehensive simulation experiments demonstrate the potential of our proposed FAC scheme to effectively optimize the scalability of the I-frame acceleration mechanism, particularly in commercial breaks. Meanwhile, the FAC scheme only slightly increases the average channel changing delay by temporarily disabling FCC (i.e., I-frame acceleration for the clients who are addicted to frequent channel zapping.

  12. Multi-Input Multi-Output Fading Channel Equalization with Constellation Selection and Space-Time Precoders

    Directory of Open Access Journals (Sweden)

    Ankita Shukla

    2011-09-01

    Full Text Available We consider multiplexing systems in correlated multiple-input multiple-output (MIMO fading channels with equal power allocated to each transmit antenna. Under several constraints, the number and subset of transmit antennas together with the transmit symbol constellations are determined assuming knowledge of the channel correlation matrices. The maximum outage data rate of the SCR receiver is seen to be close to the outage channel capacity. Identification of the channel matrix is of main concern in wireless multiple input multiple output (MIMO systems. To maximize the SNR, the best way to utilize a MIMO system is to communicate on the top singular vectors of the channel matrix. In this paper we addresses t several issues and the problem of channel tracking and equalization for multi-input multi-output (MIMO time-varying frequency-selective channels. These channels model the effects of inter-symbol interference (ISI, co-channel interference (CCI, and noise. Via singular value decomposition (SVD analysis, the precoder is used to be shown to outperform the orthogonal frequency division multiplexing (OFDM precoder in bit-error-rate (BER, transmission rate, and receiver implementation.

  13. Control works in debris-flow channels: influence on morphology and sediment transfer

    Science.gov (United States)

    Marchi, L.

    2012-04-01

    Extensive torrent control works, such as grade-control dams, debris basins, deflecting walls, etc. have been implemented in the European Alps since the last decades of 19th century. These structural measures, aimed at stabilizing channels and to control sediment transport, are also widespread in Japan and are increasingly present in other mountain regions. As debris flows are one of the most destructive processes in steep mountain channels, hydraulic works are often intended to attenuate debris-flow hazard. Multi-temporal aerial photos and historic records permit evaluating the long term effects of torrent control works on the morphological settings of the channels and the delivery of sediment. The experience arising from over one century of torrent control works in debris-flow channels of the Alps permits also to improve the management of steep headwater catchments. A basic issue in the management of debris-flow channels is the recognition of success versus failure of engineering control works. Successful debris-flow control works provide benchmarks for further implementations, whereas the failure in reducing debris-flow hazard may lead to refinements in planning and design of control works or to the choice of preferring non-structural measures for coping with debris flows. Data from historical archives on debris-flow occurrence and on the performance of control works are the basic sources of information for these analyses. Moreover, when dealing with hydraulic structures for debris-flow control, it should be reminded that the artificial morphology resulting from the construction of check dams provides only a temporary stability to the channel and adjacent banks. This stresses the importance of evaluating the state of conservation and the effectiveness of control works and implies the need for their careful and continuous maintenance. Inventories of hydraulic structures, coupled with detailed data on catchment and channel topography, sediment sources and supply

  14. Diversity Techniques for Single-Carrier Packet Retransmissions over Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Inbar Fijalkow

    2009-01-01

    Full Text Available In data packet communication systems over multipath frequency-selective channels, hybrid automatic repeat request (HARQ protocols are usually used in order to ensure data reliability. For single-carrier packet transmission in slow fading environment, an identical retransmission of the same packet, due to a decoding failure, does not fully exploit the available time diversity in retransmission-based HARQ protocols. In this paper, we compare two transmit diversity techniques, namely, cyclic frequency-shift diversity and bit-interleaving diversity. Both techniques can be integrated in the HARQ scheme in order to improve the performance of the joint detector. Their performance in terms of pairwise error probability is investigated using maximum likelihood detection and decoding. The impact of the channel memory and the modulation order on the performance gain is emphasized. In practice, we use low complexity linear filter-based equalization which can be efficiently implemented in the frequency domain. The use of iterative equalization and decoding is also considered. The performance gain in terms of frame error rate and data throughput is evaluated by numerical simulations.

  15. Blind CP-OFDM and ZP-OFDM Parameter Estimation in Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    Vincent Le Nir

    2009-01-01

    Full Text Available A cognitive radio system needs accurate knowledge of the radio spectrum it operates in. Blind modulation recognition techniques have been proposed to discriminate between single-carrier and multicarrier modulations and to estimate their parameters. Some powerful techniques use autocorrelation- and cyclic autocorrelation-based features of the transmitted signal applying to OFDM signals using a Cyclic Prefix time guard interval (CP-OFDM. In this paper, we propose a blind parameter estimation technique based on a power autocorrelation feature applying to OFDM signals using a Zero Padding time guard interval (ZP-OFDM which in particular excludes the use of the autocorrelation- and cyclic autocorrelation-based techniques. The proposed technique leads to an efficient estimation of the symbol duration and zero padding duration in frequency selective channels, and is insensitive to receiver phase and frequency offsets. Simulation results are given for WiMAX and WiMedia signals using realistic Stanford University Interim (SUI and Ultra-Wideband (UWB IEEE 802.15.4a channel models, respectively.

  16. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    Science.gov (United States)

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-11-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes.

  17. THE THEORETICAL BER PERFORMANCE ANALYSIS OF A COOPERATIVE DIVERSITY SCHEME IN FREQUENCY SELECTIVE FADING CHANNEL

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel cooperative diversity scheme based on Distributed Space-Time Block Coding and Multi-Carrier Code Division Multiple Access (DSTBC-MC-CDMA) is proposed which works well in frequency selective fading channels with multiple single-antenna users. And an analytical error model is established to describe the symbol decoding errors between interusers, based on which a close form expression for theoretical Bit Error Rate (BER) performance of the scheme is derived to analyze the influence of the interuser decoding errors on the BER performance of the scheme. Then simulation is complimented to verify the analytic result above, which also shows that the BER performance of DSTBC-MC-CDMA outgoes that of non-cooperative MC-CDMA with considerable gains. Furthermore, the simulations coincide with the theoretical results well.

  18. Channel Selection and Feature Projection for Cognitive Load Estimation Using Ambulatory EEG

    Directory of Open Access Journals (Sweden)

    Tian Lan

    2007-01-01

    Full Text Available We present an ambulatory cognitive state classification system to assess the subject's mental load based on EEG measurements. The ambulatory cognitive state estimator is utilized in the context of a real-time augmented cognition (AugCog system that aims to enhance the cognitive performance of a human user through computer-mediated assistance based on assessments of cognitive states using physiological signals including, but not limited to, EEG. This paper focuses particularly on the offline channel selection and feature projection phases of the design and aims to present mutual-information-based techniques that use a simple sample estimator for this quantity. Analyses conducted on data collected from 3 subjects performing 2 tasks (n-back/Larson at 2 difficulty levels (low/high demonstrate that the proposed mutual-information-based dimensionality reduction scheme can achieve up to 94% cognitive load estimation accuracy.

  19. A novel reduced-complexity group detection structure in MIMO frequency selective fading channels

    KAUST Repository

    Qaraqe, Khalid A.

    2010-09-01

    In this paper a novel reduced complexity detection method named modified symbol flipping method is introduced and its advantages on reducing the burden of the calculations at the receiver compared to the optimum maximum likelihood detection method on multiple input- multiple output frequency selective fading channels are explained. The initial concept of the symbol flipping method is derived from a preliminary detection scheme named bit flipping which was introduced in [1]. The detection structure employed in this paper is ing, detection, and cancellation. On the detection stage, the proposed method is employed and the results are compared to the group maximum likelihood detection scheme proposed in [2]. Simulation results show that a 6 dB performance gain can be achieved at the expense of a slight increase in complexity in comparison with the conventional symbol flipping scheme. © 2010 Crown.

  20. Diphtheria toxin-induced channels in Vero cells selective for monovalent cations

    Energy Technology Data Exchange (ETDEWEB)

    Sandvig, K.; Olsnes, S.

    1988-09-05

    Ion fluxes associated with translocation of diphtheria toxin across the surface membrane of Vero cells were studied. When cells with surface-bound toxin were exposed to low pH to induce toxin entry, the cells became permeable to Na+, K+, H+, choline+, and glucosamine+. There was no increased permeability to Cl-, SO4(-2), glucose, or sucrose, whereas the uptake of /sup 45/Ca2+ was slightly increased. The influx of Ca2+, which appears to be different from that of monovalent cations, was reduced by several inhibitors of anion transport and by verapamil, Mn2+, Co2+, and Ca2+, but not by Mg2+. The toxin-induced fluxes of N+, K+, and protons were inhibited by Cd2+. Cd2+ also protected the cells against intoxication by diphtheria toxin, suggesting that the open cation-selective channel is required for toxin translocation. The involvement of the toxin receptor is discussed.

  1. Charged residues distribution modulates selectivity of the open state of human isoforms of the voltage dependent anion-selective channel.

    Science.gov (United States)

    Amodeo, Giuseppe Federico; Scorciapino, Mariano Andrea; Messina, Angela; De Pinto, Vito; Ceccarelli, Matteo

    2014-01-01

    Voltage Dependent Anion-selective Channels (VDACs) are pore-forming proteins located in the outer mitochondrial membrane. They are responsible for the access of ions and energetic metabolites into the inner membrane transport systems. Three VDAC isoforms exist in mammalian, but their specific role is unknown. In this work we have performed extensive (overall ∼5 µs) Molecular Dynamics (MD) simulations of the human VDAC isoforms to detect structural and conformational variations among them, possibly related to specific functional roles of these proteins. Secondary structure analysis of the N-terminal domain shows a high similarity among the three human isoforms of VDAC but with a different plasticity. In particular, the N-terminal domain of the hVDAC1 is characterized by a higher plasticity, with a ∼20% occurrence for the 'unstructured' conformation throughout the folded segment, while hVDAC2, containing a peculiar extension of 11 amino acids at the N-terminal end, presents an additional 310-helical folded portion comprising residues 10' to 3, adhering to the barrel wall. The N-terminal sequences of hVDAC isoforms are predicted to have a low flexibility, with possible consequences in the dynamics of the human VDACs. Clear differences were found between hVDAC1 and hVDAC3 against hVDAC2: a significantly modified dynamics with possible important consequence on the voltage-gating mechanism. Charge distribution inside and at the mouth of the pore is responsible for a different preferential localization of ions with opposite charge and provide a valuable rationale for hVDAC1 and hVDAC3 having a Cl-/K+ selectivity ratio of 1.8, whereas hVDAC2 of 1.4. Our conclusion is that hVDAC isoforms, despite sharing a similar scaffold, have modified working features and a biological work is now requested to give evidence to the described dissimilarities. PMID:25084457

  2. Charged residues distribution modulates selectivity of the open state of human isoforms of the voltage dependent anion-selective channel.

    Directory of Open Access Journals (Sweden)

    Giuseppe Federico Amodeo

    Full Text Available Voltage Dependent Anion-selective Channels (VDACs are pore-forming proteins located in the outer mitochondrial membrane. They are responsible for the access of ions and energetic metabolites into the inner membrane transport systems. Three VDAC isoforms exist in mammalian, but their specific role is unknown. In this work we have performed extensive (overall ∼5 µs Molecular Dynamics (MD simulations of the human VDAC isoforms to detect structural and conformational variations among them, possibly related to specific functional roles of these proteins. Secondary structure analysis of the N-terminal domain shows a high similarity among the three human isoforms of VDAC but with a different plasticity. In particular, the N-terminal domain of the hVDAC1 is characterized by a higher plasticity, with a ∼20% occurrence for the 'unstructured' conformation throughout the folded segment, while hVDAC2, containing a peculiar extension of 11 amino acids at the N-terminal end, presents an additional 310-helical folded portion comprising residues 10' to 3, adhering to the barrel wall. The N-terminal sequences of hVDAC isoforms are predicted to have a low flexibility, with possible consequences in the dynamics of the human VDACs. Clear differences were found between hVDAC1 and hVDAC3 against hVDAC2: a significantly modified dynamics with possible important consequence on the voltage-gating mechanism. Charge distribution inside and at the mouth of the pore is responsible for a different preferential localization of ions with opposite charge and provide a valuable rationale for hVDAC1 and hVDAC3 having a Cl-/K+ selectivity ratio of 1.8, whereas hVDAC2 of 1.4. Our conclusion is that hVDAC isoforms, despite sharing a similar scaffold, have modified working features and a biological work is now requested to give evidence to the described dissimilarities.

  3. Fault tolerant model predictive control of open channels

    OpenAIRE

    Horváth, Klaudia; Blesa Izquierdo, Joaquim; Duviella, Eric; Chuquet, Karine

    2014-01-01

    Automated control of water systems (irrigation canals, navigation canals, rivers etc.) relies on the measured data. The control action is calculated, in case of feedback controller, directly from the on-line measured data. If the measured data is corrupted, the calculated control action will have a different effect than it is desired. Therefore, it is crucial that the feedback controller receives good quality measurement data. On-line fault detection techniques can be applied in order to dete...

  4. Flatness-based control of open-channel flow in an irrigation canal using SCADA

    OpenAIRE

    Rabbani, T.; Munier, S.; Dorchies, D.; Malaterre, P.O.; Bayen, A.; Litrico, X.

    2009-01-01

    Open channels are used to distribute water to large irrigated areas. In these systems, ensuring timely water delivery is essential to reduce operational water losses. This article derives a method for open-loop control of open channel flow, based on the Hayami model, a parabolic partial differential equation resulting from a simplification of the Saint-Venant equations. The open-loop control is represented as infinite series using differential flatness. Experimental results show the effective...

  5. Recruitment Selectivity of Single and Pairs of Transverse, Intrafascicular, Multi-channel Electrodes (TIME) in the Pig Median Nerve

    OpenAIRE

    Harreby, Kristian Rauhe; Kundu, Aritra; Geng, Bo; Maciejasz, Paweł; Guiraud, David; Stieglitz, Thomas; Boretius, Tim; Yoshida, Ken; Jensen, Winnie

    2012-01-01

    When applied in the rat model the Transverse Intrafascicular Multi-channel Electrode (TIME) showed selective nerve fascicle recruitment. But results from the larger and poly-fasicular median nerves in pigs indicated that a single TIME could not reach the entire nerve and could only selectively recruit a subset of the nerve fascicles. The use of multiple TIME structures could offer a means to achieve highly selective fascicular stimulation while reaching a larger percentage of the fascicles in...

  6. Selective inhibition of phosphodiesterase 1 relaxes urinary bladder smooth muscle: role for ryanodine receptor-mediated BK channel activation

    OpenAIRE

    Xin, Wenkuan; Soder, Rupal P; Cheng, Qiuping; Eric S. Rovner; Petkov, Georgi V.

    2012-01-01

    The large conductance voltage- and Ca2+-activated K+ (BK) channel is a major regulator of detrusor smooth muscle (DSM) excitability and contractility. Recently, we showed that nonselective phosphodiesterase (PDE) inhibition reduces guinea pig DSM excitability and contractility by increasing BK channel activity. Here, we investigated how DSM excitability and contractility changes upon selective inhibition of PDE type 1 (PDE1) and the underlying cellular mechanism involving ryanodine receptors ...

  7. Groundwater, biogeomorphic succession and controls on river channel pattern

    Science.gov (United States)

    Bätz, N.; Colombini, P.; Cherubini, P.; Lane, S. N.

    2015-12-01

    Strong feedbacks between river braiding and vegetation processes are now well-recognised. Recently, this has been illustrated in the notion of biogeomorphic succession, the transition from pioneer vegetation establishment to a fully-developed floodplain forest ecosystem. This succession also results in important vegetation-mediated feedbacks, through bank stabilisation and the capture of organic matter and fine sediments, stimulating soil formation and further enhancing the succession process itself. However, there are few studies that have addressed what this succession might mean for the evolution of channel planform, and almost no studies that have considered how this succession rates might be mediated by groundwater. The latter is a key concern for gravel-bed rivers with low water retention capacity. Here, we present results from a 2 km length of braiding-wandering river system in Switzerland (Allondon River). We show that the spatio-temporal dynamics of the groundwater table drives the biogeomorphic succession process at different rates, leading to very different river channel pattern responses. In the upper braiding-anastomosing part of the reach, the groundwater table is deeper. Here, dendrochronological data show that rates of pioneer vegetation growth are strongly dependent upon groundwater table fluctuations. Bank resistance modelling shows that vegetation-reinforcement of bank resistance is below its maximum. In the meandering lower part of the reach, with a mature floodplain forest, tree growth rates are independent of groundwater fluctuations, because trees can almost always access the higher groundwater table. Bank resistance is at its maximum. Through time, in response to disturbance frequency, the meandering tendency has migrated upstream. Thus, our results suggest that groundwater access modulates biogeomorphic succession processes in ways that determine the resultant river channel pattern.

  8. Potassium channel and NKCC cotransporter involvement in ocular refractive control mechanisms.

    Directory of Open Access Journals (Sweden)

    Sheila G Crewther

    Full Text Available Myopia affects well over 30% of adult humans globally. However, the underlying physiological mechanism is little understood. This study tested the hypothesis that ocular growth and refractive compensation to optical defocus can be controlled by manipulation of potassium and chloride ion-driven transretinal fluid movements to the choroid. Chicks were raised with +/-10D or zero power optical defocus rendering the focal plane of the eye in front of, behind, or at the level of the retinal photoreceptors respectively. Intravitreal injections of barium chloride, a non-specific inhibitor of potassium channels in the retina and RPE or bumetanide, a selective inhibitor of the sodium-potassium-chloride cotransporter were made, targeting fluid control mechanisms. Comparison of refractive compensation to 5 mM Ba(2+ and 10(-5 M bumetanide compared with control saline injected eyes shows significant change for both positive and negative lens defocus for Ba(2+ but significant change only for negative lens defocus with bumetanide (Rx(SAL(-10D = -8.6 +/- .9 D; Rx(Ba2+(-10D = -2.9 +/- .9 D; Rx(Bum(-10D = -2.9 +/- .9 D; Rx(SAL(+10D = +8.2 +/- .9 D; Rx(Ba2+(+10D = +2.8 +/- 1.3 D; Rx(Bum(+10D = +8.0 +/- .7 D. Vitreous chamber depths showed a main effect for drug conditions with less depth change in response to defocus shown for Ba(2+ relative to Saline, while bumetanide injected eyes showed a trend to increased depth without a significant interaction with applied defocus. The results indicate that both K channels and the NKCC cotransporter play a role in refractive compensation with NKCC blockade showing far more specificity for negative, compared with positive, lens defocus. Probable sites of action relevant to refractive control include the apical retinal pigment epithelium membrane and the photoreceptor/ON bipolar synapse. The similarities between the biometric effects of NKCC inhibition and biometric reports of the blockade of the retinal ON response, suggest a

  9. Thermal-hydraulic characteristics of the RBMK control and protection system channels

    International Nuclear Information System (INIS)

    The thermal-hydraulic characteristics of the RBMK-1000 control and protection system channel with rod cluster control have been calculated under different operational disturbance regimes. It has been shown that the temperature of the rod cluster control structural materials increases considerably if loss of coolant occurs. The critical element is the sleeve made of CAB1 aluminum alloy

  10. Control system of magnetic optical element power supplies for some beam channels

    International Nuclear Information System (INIS)

    The control system of the magnetic optical element power supplies for some beam channels of the IHEP accelerator, based on the micro-computer ''Elektronika-60'' and its software are described. The remote control is supplied with three Multidrop Serial Busses (31 consumer per bus). The number of controlled elements can be increased by adding one or more serial busses

  11. Multi-Channel Electroencephalogram (EEG) Signal Acquisition and its Effective Channel selection with De-noising Using AWICA for Biometric System

    OpenAIRE

    B.Sabarigiri; D.Suganyadevi

    2014-01-01

    the embedding of low cost electroencephalogram (EEG) sensors in wireless headsets gives improved authentication based on their brain wave signals has become a practical opportunity. In this paper signal acquisition along with effective multi-channel selection from a specific area of the brain and denoising using AWICA methods are proposed for EEG based personal identification. At this point, to develop identification system the steps are as follows. (i) the high-quality device with the least ...

  12. Voltage-controllable wavelength-selective optical switching based on multiply cascaded long-period fiber gratings

    Science.gov (United States)

    Han, Young-Geun; Choi, Sun-Min; Kim, Sang Hyuck; Lee, Sang Bae

    2003-11-01

    A novel wavelength-selective optical switching device based on multiply cascaded long-period fiber gratings is proposed and experimentally demonstrated. The on and off states of each channel in the optical switching device can be effectively switched by voltage-controllable coil heaters. The device has advantages of multichannel operation, multiwavelength selectivity, and bandwidth controllability. It can be useful for applications in multiwavelength operational signal gating, optical switching devices, routers, and multiplexers in optical communication systems.

  13. A Path Select Algorithm with Error Control Schemes and Energy Efficient Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sandeep Dahiya

    2012-04-01

    Full Text Available A wireless sensor network consists of a large number of sensor nodes that are spread densely to observe the phenomenon. The whole network lifetime relies on the lifetime of the each sensor node. If one node dies, it could lead to a separation of the sensor network. Also a multi hop structure and broadcast channel of wireless sensornecessitate error control scheme to achieve reliable data transmission. Automatic repeat request (ARQ and forward error correction (FEC are the key error control strategies in wire sensor network. In this paper we propose a path selection algorithm with error control schemes using energy efficient analysis.

  14. Modular Design of the Selectivity Filter Pore Loop in a Novel Family of Prokaryotic ‘Inward Rectifier’ (NirBac) channels

    OpenAIRE

    Lejla Zubcevic; Shizhen Wang; Bavro, Vassiliy N.; Sun-Joo Lee; Nichols, Colin G.; Stephen J. Tucker

    2015-01-01

    Potassium channels exhibit a modular design with distinct structural and functional domains; in particular, a highly conserved pore-loop sequence that determines their ionic selectivity. We now report the functional characterisation of a novel group of functionally non-selective members of the prokaryotic ‘inward rectifier’ subfamily of K+ channels. These channels share all the key structural domains of eukaryotic and prokaryotic Kir/KirBac channels, but instead possess unique pore-loop selec...

  15. Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers

    Science.gov (United States)

    Oliver, A. E.; Deamer, D. W.

    1994-01-01

    Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two

  16. Ferrofluid magnetoviscous control of wall flow channeling in porous media

    Institute of Scientific and Technical Information of China (English)

    Fa(ic)al Larachi; Damien Desvigne

    2007-01-01

    We analyzed the phenomenon of ferrofluid magnetoviscosity in high-permeability wall-region non-magnetic porous media of the Müller kind.After upscaling the pore-level ferrohydrodynamic model, we obtained a simplified volume-average zero-order axisymmetric model for non-Darcy non-turbulent flow of steady-state isothermal incompressible Newtonian ferrofluids through a porous medium experiencing external constant bulk-flow oriented gradient magnetic field, ferrofluid self-consistent demagnetizing field and induced magnetic field in the solid. The model was explored in contexts plagued by wall flow maldistribution due to low column-to-particle diameter ratios. It was shown that for proper magnetic field arrangement, wall channeling can be reduced by inflating wall flow resistance through magnetovisco-thickening and Kelvin body force density which reroute a fraction of wall flow towards bed core.

  17. Ultrafast nuclear dynamics in halomethanes studied with time-resolved Coulomb explosion imaging and channel-selective Fourier spectroscopy

    Science.gov (United States)

    Malakar, Y.; Kaderiya, B.; Pearson, W. L.; Ziaee, F.; Kanaka Raju, P.; Zohrabi, M.; Jensen, K.; Rajput, J.; Ben-Itzhak, I.; Rolles, D.; Rudenko, A.

    2016-05-01

    Halomethanes have recently attracted considerable attention since they often serve as prototype systems for laser-controlled chemistry (e.g., selective bond breaking or concerted elimination reactions), and are important molecules in atmospheric chemistry. Here we combine a femtosecond laser pump-probe setup with coincident 3D ion momentum imaging apparatus to study strong-field induced nuclear dynamics in methane and several of its halogenated derivatives (CH3 I, CH2 I2, CH2 ICl). We apply a time-resolved Coulomb explosion imaging technique to map the nuclear motion on both, bound and continuum potential surfaces, disentangle different fragmentation pathways and, for halogenated molecules, observe clear signatures of vibrational wave packets in neutral or ionized states. Channel-selective and kinetic-energy resolved Fourier analysis of these data allows for unique identification of different electronic states and vibrational modes responsible for a particular structure. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. DOE. K. R. P. and W. L. P. supported by NSF Award No. IIA-143049. K.J. supported by the NSF-REU Grant No. PHYS-1461251.

  18. Inhibition of T cell proliferation by selective block of Ca(2+)-activated K(+) channels

    DEFF Research Database (Denmark)

    Jensen, B S; Odum, Niels; Jorgensen, N K;

    1999-01-01

    established. The recent cloning of the Ca(2+)-activated, intermediate-conductance K(+) channel (IK channel) has enabled a detailed investigation of the role of this highly Ca(2+)-sensitive K(+) channel in the calcium signaling and subsequent regulation of T cell proliferation. The role IK channels play in T...... cell activation and proliferation has been investigated by using various blockers of IK channels. The Ca(2+)-activated K(+) current in human T cells is shown by the whole-cell voltage-clamp technique to be highly sensitive to clotrimazole, charybdotoxin, and nitrendipine, but not to ketoconazole...... inhibited after block of IK channels by clotrimazole. Clotrimazole and cyclosporin A act synergistically to inhibit T cell proliferation, which confirms that block of IK channels affects the process downstream from T cell receptor activation. We suggest that IK channels constitute another target for immune...

  19. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels.

    Science.gov (United States)

    Xu, Yan; Furutani, Shogo; Ihara, Makoto; Ling, Yun; Yang, Xinling; Kai, Kenji; Hayashi, Hideo; Matsuda, Kazuhiko

    2015-01-01

    Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori) larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA)-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR) RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to 10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs. PMID:25902139

  20. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels.

    Directory of Open Access Journals (Sweden)

    Yan Xu

    Full Text Available Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to 10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs.

  1. A Non-canonical Voltage-Sensing Mechanism Controls Gating in K2P K(+) Channels.

    Science.gov (United States)

    Schewe, Marcus; Nematian-Ardestani, Ehsan; Sun, Han; Musinszki, Marianne; Cordeiro, Sönke; Bucci, Giovanna; de Groot, Bert L; Tucker, Stephen J; Rapedius, Markus; Baukrowitz, Thomas

    2016-02-25

    Two-pore domain (K2P) K(+) channels are major regulators of excitability that endow cells with an outwardly rectifying background "leak" conductance. In some K2P channels, strong voltage-dependent activation has been observed, but the mechanism remains unresolved because they lack a canonical voltage-sensing domain. Here, we show voltage-dependent gating is common to most K2P channels and that this voltage sensitivity originates from the movement of three to four ions into the high electric field of an inactive selectivity filter. Overall, this ion-flux gating mechanism generates a one-way "check valve" within the filter because outward movement of K(+) induces filter opening, whereas inward movement promotes inactivation. Furthermore, many physiological stimuli switch off this flux gating mode to convert K2P channels into a leak conductance. These findings provide insight into the functional plasticity of a K(+)-selective filter and also refine our understanding of K2P channels and the mechanisms by which ion channels can sense voltage. PMID:26919430

  2. NUMERICAL SIMULATION OF ICE CONTROL EFFECT OF SOLAR ENERGY ON TIBETAN CHANNELS

    Institute of Scientific and Technical Information of China (English)

    AN Rui-dong; CHEN Ming-qian; LI Ran; Banjiuciren; SHI Yun-qiang

    2007-01-01

    With the Tanghe Diversion Channel in Tibet as an example, the theoretical study on the ice control effect of the solar sacks was conducted based on the previous study. The numerical simulation method was adopted and a one-dimensional numerical model for ice crystal in diversion channels in high-altitude cold regions was developed in this article. The heat transfer through the air-water interface and the mass transfer between ice and water were considered in the model. The model was validated by the field observation data on the diversion channel of the Tanghe Hydropower Station. The results show that the ice control effect of the solar sacks is obvious in the channel with large mass flow rate in the high-altitude cold regions.

  3. Filtering random matrices: the effect of incomplete channel control in multiple scattering.

    Science.gov (United States)

    Goetschy, A; Stone, A D

    2013-08-01

    We present an analytic random matrix theory for the effect of incomplete channel control on the measured statistical properties of the scattering matrix of a disordered multiple-scattering medium. When the fraction of the controlled input channels, m1, and output channels, m2, is decreased from unity, the density of the transmission eigenvalues is shown to evolve from the bimodal distribution describing coherent diffusion, to the distribution characteristic of uncorrelated Gaussian random matrices, with a rapid loss of access to the open eigenchannels. The loss of correlation is also reflected in an increase in the information capacity per channel of the medium. Our results have strong implications for optical and microwave experiments on diffusive scattering media. PMID:23971574

  4. Main-channel slopes of selected streams in Iowa for estimation of flood-frequency discharges

    Science.gov (United States)

    Eash, David A.

    2003-01-01

    This report describes a statewide study conducted to develop main-channel slope (MCS) curves for 138 selected streams in Iowa with drainage areas greater than 100 square miles. MCS values determined from the curves can be used in regression equations for estimating floodfrequency discharges. Multivariable regression equations previously developed for two of the three hydrologic regions defined for Iowa require the measurement of MCS. Main-channel slope is a difficult measurement to obtain for large streams using 1:24,000-scale topographic maps. The curves developed in this report provide a simplified method for determining MCS values for sites located along large streams in Iowa within hydrologic Regions 2 and 3. The curves were developed using MCS values quantified for 2,058 selected sites along 138 selected streams in Iowa. A geographic information system (GIS) technique and 1:24,000-scale topographic data were used to quantify MCS values for the stream sites. The sites were selected at about 5-mile intervals along the streams. River miles were quantified for each stream site using a GIS program. Data points for river-mile and MCS values were plotted and a best-fit curve was developed for each stream. An adjustment was applied to all 138 curves to compensate for differences in MCS values between manual measurements and GIS quantifications. The multivariable equations for Regions 2 and 3 were developed using manual measurements of MCS. A comparison of manual measurements and GIS quantifications of MCS indicates that manual measurements typically produce greater values of MCS compared to GIS quantifications. Median differences between manual measurements and GIS quantifications of MCS are 14.8 and 17.7 percent for Regions 2 and 3, respectively. Comparisons of percentage differences between flood-frequency discharges calculated using MCS values of manual measurements and GIS quantifications indicate that use of GIS values of MCS for Region 3 substantially

  5. Computer controlled multiple channel high voltage power supply [Paper No.: L8

    International Nuclear Information System (INIS)

    This paper describes the design of a computer controlled high voltage multiple channel power supply for use in Gamma Ray Astrophysics Experiment (GRAPE). Each channel is rated for 2.5 kV, 1mA with over current protection and output voltage read back facility. A single HV supply on a single width NIM module has been tried successfully. At present 8 channels on a module is being tried to make a very compact HV system. (author). 2 refs., 2 figs

  6. Developing control room operator selection procedures

    International Nuclear Information System (INIS)

    PDRI is performing a two-year study to identify the tasks performed and attributes required in electric power generating plant operating jobs, and focusing on the control room operator position. Approximately 65 investor-owned utilities are participating in the study

  7. Structure and selectivity of novel ω-conotoxins and conus catus that target neuronal calcium channel subtypes

    International Nuclear Information System (INIS)

    Full text: ω-Conotoxins selective for N-type voltage-sensitive calcium channels have promising therapeutic applications in conditions such as pain and neurodegeneration following cerebral ischaemia. Here we report the discovery of novel conotoxins from the piscivorous snail Conus carus using 125I-GVIA binding to rat brain membrane to guide fractionation of crude venom, and cloning to identify the expressed gene products from the venom duct tissue. Four peptides were isolated and named ω-conotoxins CVIA-D (CVIA-D) on the basis of their pharmacology and structure. CVIA-D had varying extents of homology to other ω-conotoxins, with loop 4 of CVID showing significant sequence divergence. From binding studies in rat brain, the rank order of potency to displace 125I-GVIA from N-type calcium channel (CVID = GVIA=MVIIA > CVIA > CVIC = CVIB > MVIIC) was reversed at the P/Q-type calcium channel (defined by 125I-MVIIC). CVID was most selective for N-type vs P/Q-type calcium channels, being 1.5 to 2-orders of magnitude more selective than GVIA and MVIIA, respectively. CVIA-D each inhibited neurally-evoked contractions in rat vas deferens in a reversible manner, with potencies that correlated with their ability to inhibit 125I-GVIA binding. Compared with GVIA, CVID was a more potent inhibitor of central N-type calcium channels (α1,B-dexpressed in Xenopus oocytes) than of peripheral N-type calcium channels (rat vas deferens). 1H NMR studies revealed that CVID adopts a similar 3D fold to other ω-conotoxins. However, in contrast to GVIA, MVIIA or MVIIC, CVID has two hydrogen bonds that hold loops 2 and 4 proximal, a factor that may contribute to the enhanced ability of CVID to discriminate among neuronal calcium channels

  8. Exact Performance Analysis of Partial Relay Selection Based on Shadowing Side Information over Generalized Composite Fading Channels

    CERN Document Server

    Yilmaz, Ferkan

    2011-01-01

    Relay technology has recently gained great interest in millimeter wave (60 GHz or above) radio frequencies as a promising transmission technique improving the quality of service, providing high data rate, and extending the coverage area without additional transmit power in deeply shadowed wireless environments. The performance of relay-based systems depends considerably on which relay selection protocols are used. These protocols are typically using the channel side information (CSI). Specifically, the relay terminal (RT) is chosen among all available RTs by a centralized entity (CE) which receives all RTs' CSI via feedback channels. However, in the millimeter wave radio frequencies, the rate of the variation of the CSI is much higher than that of a classical system operating in 6 GHz frequencies under the same mobility conditions, which evidently results in a serious problem causing outdated (inaccurate) CSI for the relay selection protocol at the CE since the feedback channels have a backhaul / transmission...

  9. Quantitative analysis of the water occupancy around the selectivity filter of a K+ channel in different gating modes

    OpenAIRE

    Weingarth, Markus; van der Cruijsen, Elwin A. W.; Ostmeyer, Jared; Lievestro, Sylke; Roux, Benoît; Baldus, Marc

    2014-01-01

    Recovery in K+ channels, i.e., the transition from the inactivated non-conductive selectivity filter conformation towards the conductive conformation, occurs on a timescale of the order of seconds, which is astonishingly long, given that the structural differences among the filter conformations are faint (< 1 Å). Computational studies and electrophysiological measurements suggested that buried water molecules bound behind the selectivity filter are at the origin of the slowness of recovery in...

  10. Quantitative analysis of the water occupancy around the selectivity filter of a K+ channel in different gating modes

    NARCIS (Netherlands)

    Weingarth, Markus; Van Der Cruijsen, Elwin A W; Ostmeyer, Jared; Lievestro, Sylke; Roux, Benoiît; Baldus, Marc

    2014-01-01

    Recovery in K+ channels, that is, the transition from the inactivated nonconductive selectivity filter conformation toward the conductive conformation, occurs on a time scale of the order of seconds, which is astonishingly long, given that the structural differences among the filter conformations ar

  11. Frequency-selective fading statistics of shallow-water acoustic communication channel with a few multipaths

    Science.gov (United States)

    Bae, Minja; Park, Jihyun; Kim, Jongju; Xue, Dandan; Park, Kyu-Chil; Yoon, Jong Rak

    2016-07-01

    The bit error rate of an underwater acoustic communication system is related to multipath fading statistics, which determine the signal-to-noise ratio. The amplitude and delay of each path depend on sea surface roughness, propagation medium properties, and source-to-receiver range as a function of frequency. Therefore, received signals will show frequency-dependent fading. A shallow-water acoustic communication channel generally shows a few strong multipaths that interfere with each other and the resulting interference affects the fading statistics model. In this study, frequency-selective fading statistics are modeled on the basis of the phasor representation of the complex path amplitude. The fading statistics distribution is parameterized by the frequency-dependent constructive or destructive interference of multipaths. At a 16 m depth with a muddy bottom, a wave height of 0.2 m, and source-to-receiver ranges of 100 and 400 m, fading statistics tend to show a Rayleigh distribution at a destructive interference frequency, but a Rice distribution at a constructive interference frequency. The theoretical fading statistics well matched the experimental ones.

  12. Research Spotlight: What controls the shape of sediment channels in river deltas?

    Science.gov (United States)

    Tretkoff, Ernie

    2011-03-01

    When turbulent, sediment-filled rivers empty into oceans and lakes, the channels often divide repeatedly to form triangular deltas. Some channels, however, travel long distances before bifurcating, creating elongated channels. Understanding how these patterns arise could be useful for designing wetland restoration schemes on river deltas. Seeking to explain the conditions under which elongated channels form, Falcini and Jerolmack considered an analogy with cold filaments in ocean currents, in which high potential vorticity (a measure that combines the rotation of a flow with its thermal gradient) helps a filament hold a coherent structure over long distances. The researchers introduced a model that incorporates sediment concentration and fluid vorticity, to derive a new “potential vorticity” equation that describes sedimentation patterns at the river mouth. Their model shows that a high potential vorticity is needed for the creation of elongated channels, and their comparison to modeling, laboratory, and field studies confirms that potential vorticity is a primary control on channel morphology. The new model could help to understand the shape of the iconic Mississippi River delta and may aid in the design of proposed channel diversions there and in other deltas. (Journal of Geophysical Research-Earth Surface, doi:10.1029/2010JF001802, 2010)

  13. Integrating nanopore sensors within microfluidic channel arrays using controlled breakdown.

    Science.gov (United States)

    Tahvildari, Radin; Beamish, Eric; Tabard-Cossa, Vincent; Godin, Michel

    2015-03-21

    Nanopore arrays are fabricated by controlled dielectric breakdown (CBD) in solid-state membranes integrated within polydimethylsiloxane (PDMS) microfluidic devices. This technique enables the scalable production of independently addressable nanopores. By confining the electric field within the microfluidic architecture, nanopore fabrication is precisely localized and electrical noise is significantly reduced. Both DNA and protein molecules are detected to validate the performance of this sensing platform. PMID:25631885

  14. Control structure selection for vapor compression refrigeration cycle

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Xiaohong; Li, Shaoyuan [Shanghai Jiao Tong Univ., Shanghai (China). Dept. of Automation; Shandong Jianzhu Univ., Jinan (China). School of Information and Electrical Engineering; Cai, Wenjian; Ding, Xudong [Nanyang Technological Univ., Singapore (Singapore). School of Electrical and Electronic Engineering

    2013-07-01

    A control structure selection criterion which can be used to evaluate the control performance of different control structures for the vapor compression refrigeration cycle is proposed in this paper. The calculation results of the proposed criterion based on the different reduction models are utilized to determine the optimized control model structure. The effectiveness of the criterion is verified by the control effects of the model predictive control (MPC) controllers which are designed based on different model structures. The response of the different controllers applied on the actual vapor compression refrigeration system indicate that the best model structure is in consistent with the one obtained by the proposed structure selection criterion which is a trade-off between computation complexity and control performance.

  15. Control of mesoscopic transport by modifying transmission channels in opaque media

    CERN Document Server

    Sarma, Raktim; Liew, Seng Fatt; Guy, Mikhael; Cao, Hui

    2015-01-01

    While controlling particle diffusion in a confined geometry is a popular approach taken by both natural and artificial systems, it has not been widely adopted for controlling light transport in random media, where wave interference effects play a critical role. The transmission eigenchannels determine not only light propagation through the disordered system but also the energy concentrated inside. Here we propose and demonstrate an effective approach to modify these channels, whose structures are considered to be universal in conventional diffusive waveguides. By adjusting the waveguide geometry, we are able to alter the spatial profiles of the transmission eigenchannels significantly and deterministically from the universal ones. In addition, propagating channels may be converted to evanescent channels or vice versa by tapering the waveguide cross-section. Our approach allows to control not only the transmitted and reflected light, but also the depth profile of energy density inside the scattering system. In...

  16. Perfect controlled joint remote state preparation independent of entanglement degree of the quantum channel

    International Nuclear Information System (INIS)

    We construct a quantum circuit to produce a task-oriented partially entangled state and use it as the quantum channel for controlled joint remote state preparation. Unlike most previous works, where the parameters of the quantum channel are given to the receiver who can accomplish the task only probabilistically by consuming auxiliary resource, operation and measurement, here we give them to the supervisor. Thanks to the knowledge of the task-oriented quantum channel parameters, the supervisor can carry out proper complete projective measurement, which, combined with the feed-forward technique adapted by the preparers, not only much economizes (simplifies) the receiver's resource (operation) but also yields unit total success probability. Notably, such apparent perfection does not depend on the entanglement degree of the shared quantum channel. Our protocol is within the reach of current quantum technologies. - Highlights: • Controlled joint remote state preparation is considered. • Quantum circuit is proposed to produce task-oriented partially entangled channel. • The quantum channel parameter is given to the supervisor (not to the receiver). • Unit success probability without additional resource/operations/measurement. • Perfection is achieved regardless of the shared entanglement degree

  17. CALCULATION METHODS OF OPTIMAL ADJUSTMENT OF CONTROL SYSTEM THROUGH DISTURBANCE CHANNEL

    Directory of Open Access Journals (Sweden)

    I. M. Golinko

    2014-01-01

    Full Text Available In the process of automatic control system debugging the great attention is paid to determining formulas’ parameters of optimal dynamic adjustment of regulators, taking into account the dynamics of Objects control. In most cases the known formulas are oriented on design of automatic control system through channel “input-output definition”. But practically in all continuous processes the main task of all regulators is stabilization of output parameters. The Methods of parameters calculation for dynamic adjustment of regulations were developed. These methods allow to optimize the analog and digital regulators, taking into account minimization of regulated influences. There were suggested to use the fact of detuning and maximum value of regulated influence. As the automatic control system optimization with proportional plus reset controllers on disturbance channel is an unimodal task, the main algorithm of optimization is realized by Hooke – Jeeves method. For controllers optimization through channel external disturbance there were obtained functional dependences of parameters calculations of dynamic proportional plus reset controllers from dynamic characteristics of Object control. The obtained dependences allow to improve the work of controllers (regulators of automatic control on external disturbance channel and so it allows to improve the quality of regulation of transient processes. Calculation formulas provide high accuracy and convenience in usage. In suggested method there are no nomographs and this fact expels subjectivity of investigation in determination of parameters of dynamic adjustment of proportional plus reset controllers. Functional dependences can be used for calculation of adjustment of PR controllers in a great range of change of dynamic characteristics of Objects control.

  18. KATP channels are not essential for pressure-dependent control of renin secretion

    DEFF Research Database (Denmark)

    Jensen, B L; Gambaryan, S; Scholz, H;

    1998-01-01

    This study aimed to investigate the functional role of ATP-sensitive K+ (KATP) channels in the control of renin secretion by renal perfusion pressure. We studied the effect of openers and blockers of KATP-channels on basal- and low-pressure-induced renin secretion from isolated perfused rat kidneys......, all of which suggests that KATP channel openers stimulate renin secretion at the level of JG cells. A decrease in the perfusion pressure from 13.3 to 9.33 kPa (100 mmHg to 70 mmHg) increased renin secretion twofold, and cromakalim further increased renin secretion. At 5.33 kPa (40 mmHg) renin...... pathway that includes a decrease in JG cell calcium. KATP channels are not essentially involved in pressure-sensitive renin secretion....

  19. On the delay effects of different channels in Internet-based networked control systems

    Science.gov (United States)

    Zhao, Yun-Bo; Kim, Jongrae; Sun, Xi-Ming; Liu, Guo-Ping

    2013-11-01

    The sensor-to-controller and the controller-to-actuator delays in networked control systems (NCSs) are investigated for the first time with respect to their different effects on the system performance. This study starts with identifying the delay-independent and delay-dependent control laws in NCSs, and confirms that only two delay-dependent control laws can cause different delay effects in different channels. The conditions under which the different delays in different channels can cause different effects are then given for both delay-dependent control laws. The results are verified by numerical examples. Potentially, these results can be regarded as important design principles in the practical implementation of NCSs.

  20. Efficient fidelity control by stepwise nucleotide selection in polymerase elongation

    CERN Document Server

    Yu, Jin

    2014-01-01

    Polymerases select nucleotides before incorporating them for chemical synthesis during gene replication or transcription. How the selection proceeds stepwise efficiently to achieve sufficiently high fidelity and speed is essential for polymerase function. We examined step-by-step selections that have conformational transition rates tuned one at time in the polymerase elongation cycle, with a controlled differentiation free energy at each checkpoint. The elongation is sustained at non-equilibrium steady state with constant free energy input and heat dissipation. It is found that error reduction capability does not improve for selection checkpoints down the reaction path. Hence, it is essential to select early to achieve an efficient fidelity control. In particular, for two consecutive selections that reject the wrong substrate back and inhibit it forward from a same kinetic state, the same error rates are obtained at the same free energy differentiation. The initial screening is indispensible for maintaining t...

  1. Channel control ASIC for the CMS hadron calorimeter front end readout module

    International Nuclear Information System (INIS)

    The Channel Control ASIC (CCA) is used along with a custom Charge Integrator and Encoder (QIE) ASIC to digitize signals from the hybrid photo diodes (HPDs) and photomultiplier tubes (PMTs) in the CMS hadron calorimeter. The CCA sits between the QIE and the data acquisition system. All digital signals to and from the QIE pass through the CCA chip. One CCA chip interfaces with two QIE channels. The CCA provides individually delayed clocks to each of the QIE chips in addition to various control signals. The QIE sends digitized PMT or HPD signals and time slice information to the CCA, which sends the data to the data acquisition system through an optical link

  2. Performance analysis of best relay selection scheme for amplify-and-forward cooperative networks in identical Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2010-06-01

    In cooperative communication networks, the use of multiple relays between the source and the destination was proposed to increase the diversity gain. Since the source and all the relays must transmit on orthogonal channels, multiple relay cooperation is considered inefficient in terms of channel resources and bandwidth utilization. To overcome this problem, the concept of best relay selection was recently proposed. In this paper, we analyze the performance of the best relay selection scheme for a cooperative network with multiple relays operating in amplify-and-forward (AF) mode over identical Nakagami-m channels using exact source-relay-destination signal to noise ratio (SNR) expression. We derive accurate closed form expressions for various system parameters including probability density function (pdf) of end-to-end SNR, average output SNR, average probability of bit error and average channel capacity. T he analytical results are verified through extensive simulations. It is shown that the best relay selection scheme performs better than the regular all relay cooperation.

  3. Three-Party Controlled Quantum Teleportation with Six-Photon Entangled States via Collective Noise Channel

    International Nuclear Information System (INIS)

    Two three-party controlled quantum teleportation protocols using six-photon entangled states are proposed for circumventing collective noise. It can be performed in collective-dephasing noise or collective-rotation noise with unitary successful probability. Due to the symmetry of the quantum channel, each participant can act as a sender, a receiver or a controller. Moreover, it can be generalized to multiparty controlled teleportation protocols. (authors)

  4. Selectivity of a Singly Permeating Ion in Nonselective NaK Channel: Combined QM and MD Based Investigations.

    Science.gov (United States)

    Sadhu, Biswajit; Sundararajan, Mahesh; Bandyopadhyay, Tusar

    2015-10-01

    Ion channels, such as potassium channels are known to discriminate ions to achieve remarkable selective transportation of K(+) over Na(+) through the membrane. The recently reported NaK ion channel, on the contrary, seems to be an exception, as it is observed to permeate most of the group IA alkali metal cations and hence is suggested to be nonselective in nature. However, does that correspond to a complete annihilation of selectivity inside the selectivity filter (SF) of the channel? What is the origin of such nonselectivity/selectivity, if any? The present computational study is an extensive multiscale modeling approach to find the probable answers to these intriguing questions. Here, we have used density functional theory (DFT) based calculations using a realistic truncated model of SF from the crystal structures of the NaK ion channel to evaluate the binding of various alkali metal ions (Na(+), K(+) and Cs(+)), free from "contamination" due to the absence any other "rivalry" cations, in its different binding sites. Among all of the possible binding sites, a vestibule is noticed to be nonselective and seen to act as a probable binding site only in the presence of multiple ions. Binding sites S3 and S4 are found to be selective for K(+) and Na(+), respectively. As an important observation, we find that calculations on oversimplified models using an isolated ion binding site may lead to an erroneous selectivity trend as it neglects the synergetics of consecutive binding sites on the final outcome. Energy decomposition analysis revealed ion-dipole electrostatics as the major contributing interaction in metal-bound binding sites. Our investigations find that although NaK is permeable to monovalent alkali metal ions, strongly "site specific" selectivity does exist at the three well-defined noncontiguous binding sites of the SF. Different important physicomechanical parameters (such as ligating environment, synergistic influence of binding sites, and topological

  5. Tackling the Combined Effects of Reverberation and Masking Noise Using Ideal Channel Selection

    Science.gov (United States)

    Hazrati, Oldooz; Loizou, Philipos C.

    2012-01-01

    Purpose: In this article, a new signal-processing algorithm is proposed and evaluated for the suppression of the combined effects of reverberation and noise. Method: The proposed algorithm decomposes, on a short-term basis (every 20 ms), the reverberant stimuli into a number of channels and retains only a subset of the channels satisfying a…

  6. An external sodium ion binding site controls allosteric gating in TRPV1 channels.

    Science.gov (United States)

    Jara-Oseguera, Andres; Bae, Chanhyung; Swartz, Kenton J

    2016-01-01

    TRPV1 channels in sensory neurons are integrators of painful stimuli and heat, yet how they integrate diverse stimuli and sense temperature remains elusive. Here, we show that external sodium ions stabilize the TRPV1 channel in a closed state, such that removing the external ion leads to channel activation. In studying the underlying mechanism, we find that the temperature sensors in TRPV1 activate in two steps to favor opening, and that the binding of sodium to an extracellular site exerts allosteric control over temperature-sensor activation and opening of the pore. The binding of a tarantula toxin to the external pore also exerts control over temperature-sensor activation, whereas binding of vanilloids influences temperature-sensitivity by largely affecting the open/closed equilibrium. Our results reveal a fundamental role of the external pore in the allosteric control of TRPV1 channel gating and provide essential constraints for understanding how these channels can be tuned by diverse stimuli. PMID:26882503

  7. HOW TO SELECT APPROPRIATE HUMAN RESOURCE CONTROLLING INDICATORS

    OpenAIRE

    Monika Dugelova; Mariana Strenitzerova

    2015-01-01

    Human resource controlling represents a company’s strategic method to support its role is planning, checking, and managing—including information supplement for human resources department. Human resource controlling helps with optimization and transformation of human resource functions and with general human resource management. Our survey deals with the implementation of human resource controlling in information technology companies. The selection of appropriate human resource controlling too...

  8. Response selection involves executive control: evidence from the selective interference paradigm.

    Science.gov (United States)

    Szmalec, Arnaud; Vandierendonck, André; Kemps, Eva

    2005-04-01

    In the present study, we investigated whether response selection involves executive control, using the selective interference paradigm within Baddeley's (1986) working memory framework. The interference from response selection was estimated by comparing the patterns of dual-task interference of simple and choice RT tasks with those of a number of established working memory tasks. In Experiment 1, we compared impairment of forward and backward verbal serial recall from the RT tasks and articulatory suppression. Experiment 2 measured the adverse effects of the RT tasks and matrix tapping on forward and backward visuospatial serial recall. Finally, in Experiment 3, we examined the impairment from the RT tasks with two measures of executive control--namely, letter and category fluency. Altogether, the three experiments demonstrated that response selection interferes with executive control and that the interference is not produced at the level of working memory's slave systems, which supports the assumption of executive involvement in response selection. PMID:16156187

  9. T-type calcium channel: a privileged gate for calcium entry and control of adrenal steroidogenesis

    Directory of Open Access Journals (Sweden)

    Michel Florian Rossier

    2016-05-01

    Full Text Available Intracellular calcium plays a crucial role in modulating a variety of functions such as muscle contraction, hormone secretion, gene expression or cell growth. Calcium signaling has been however shown to be more complex than initially thought. Indeed, it is confined within cell microdomains and different calcium channels are associated with different functions, as shown by various channelopathies.Sporadic mutations on voltage-operated L-type calcium channels in adrenal glomerulosa cells have been shown recently to be the second most prevalent genetic abnormalities present in human aldosterone-producing adenoma. The observed modification of the threshold of activation of the mutated channels not only provides an explanation for this gain of function but reminds us on the importance of maintaining adequate electrophysiological characteristics to make channels able to exert specific cellular functions. Indeed, the contribution to steroid production of the various calcium channels expressed in adrenocortical cells is not equal and the reason has been investigated for a long time. Given the very negative resting potential of these cells, and the small membrane depolarization induced by their physiological agonists, low threshold T-type calcium channels are particularly well suited for responding under these conditions and conveying calcium into the cell, at the right place for controlling steroidogenesis. In contrast, high threshold L-type channels are normally activated by much stronger cell depolarizations. The fact that dihydropyridine calcium antagonists, specific for L-type channels, are poorly efficient for reducing aldosterone secretion either in vivo or in vitro, strongly supports the view that these two types of channels differently affect steroid biosynthesis.Whether a similar analysis is transposable to fasciculata cells and cortisol secretion is one of the questions addressed in the present review. No similar mutations on L-type or T

  10. Ferrofluid magnetoviscous control of wall flow channeling in porous media

    Institute of Scientific and Technical Information of China (English)

    Faal; Larachi

    2007-01-01

    [1]Bacri,J.C.,Perzynski,R.,Shliomis,M.I.,& Burde,G.I.(1995).Negative viscosity effect in a magnetic fluid.Physical Review Letters,75(11),2128-2131.[2]Felderhof,B.U.(2001).Flow of a ferrofluid down a tube in an oscillating magnetic field.Physical Review E,64(021508),1-7.[3]Khuzir,P.,Bossis,G.,Bashtovoi,V.,& Volkova,O.(2003).Flow of magnetorheological fluid through porous media.European Journal of Mechanics B/Fluids,22,331-343.[4]McTague,J.P.(1969).Magnetoviscosity of magnetic colloids.Journal of Chemical Physics,51,133-136.[5]Odenbach,S.(2003).Magnetic fluids-Suspensions of magnetic dipoles and their magnetic control.Journal of Physics:Condensed Matter,15,S 1497-S1508.[6]Rinaldi,C.,& Zahn,M.(2002).Effects of spin viscosity on ferrofluid flow profiles in alternating and rotating magnetic fields.Physics of Fluids,14,2847-2870.[7]Rosensweig,R.E.(1997).Ferrohydrodynamics.New York:Dover Publications.[8]Schumacher,K.R.,Sellien,I.,Knoke,G.S.,Cadet,T.,& Finlayson,B.A.(2003).Experiment and simulation of laminar and turbulent ferrofluid pipe flow in an oscillating magnetic field.Physical Review E,67(026308),1-11.[9]Shliomis,M.I.(1972).Effective viscosity of magnetic suspensions.Soviet Physics JETP,34,1291-1294.[10]Whitaker,S.(1999).Theory and applications of transport in porous media.Dordrecht:Kluwer Academic Press.[11]Zeuner,A.,Richter,R.,& Rehberg,I.(1998).Experiments on negative and positive magnetoviscosity in an alternating magnetic field.Physical Review E,58,62876293.

  11. Performance analysis of selective cooperation in amplify-and-forward relay networks over identical Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2011-05-02

    In cooperative communications, multiple relays between a source and a destination can increase the diversity gain. Because all the nodes must use orthogonal channels, multiple-relay cooperation becomes spectrally inefficient. Therefore, a bestrelay selection scheme was recently proposed. In this paper, we analyzed the performance of this scheme for a system with the relays operating in amplify-and-forward mode over identical Nakagami-m channels using an exact source-relay-destination signal-to-noise ratio (SNR).We derived accurate closed-form expressions for various system parameters including the probability density function of end-to-end SNR, the average output SNR, the bit error probability, and the channel capacity. The analytical results were verified through Monte Carlo simulations. Copyright © 2011 John Wiley & Sons, Ltd.

  12. Data Refinement and Channel Selection for a Portable E-Nose System by the Use of Feature Feedback

    Directory of Open Access Journals (Sweden)

    Yoonseok Yang

    2010-11-01

    Full Text Available We propose a data refinement and channel selection method for vapor classification in a portable e-nose system. For the robust e-nose system in a real environment, we propose to reduce the noise in the data measured by sensor arrays and distinguish the important part in the data by the use of feature feedback. Experimental results on different volatile organic compounds data show that the proposed data refinement method gives good clustering for different classes and improves the classification performance. Also, we design a new sensor array that consists only of the useful channels. For this purpose, each channel is evaluated by measuring its discriminative power based on the feature mask used in the data refinement. Through the experimental results, we show that the new sensor array improves both the classification rates and the efficiency in computation and data storage.

  13. Examining the Relationship Between Flexible Resources and Health Information Channel Selection.

    Science.gov (United States)

    Manierre, Matthew

    2016-01-01

    This study examines how variations in flexible resources influence where individuals begin their search for health information. Access to flexible resources such as money, power, and knowledge can alter the accessibility of channels for health information, such as doctors, the Internet, and print media. Using the HINTS 3 sample, whether information channel utilization is predicted by the same factors in two groups with distinct levels of access to flexible resources, as approximated by high and low levels of education, is investigated. Differences in access to flexible resources are hypothesized to produce variations in channel utilization in bivariate analyses, as well as changes in coefficient strength and statistical significance in multivariate models. Multinomial logit models were used to assess how a number of variables influence the probability of using a specific information channel first in either flexible resource group. Results suggest that individuals with higher levels of education, a proxy for flexible resources, are more likely to report seeking information from the Internet first, which is consistent with research on the digital divide. It appears that diminished access to flexible resources is also associated with heightened utilization of offline channels, including doctors. A handful of differences in predictors were found between the low and high flexible resource groups when multivariate models were compared. Future research should take into account the distinctions between different offline channels while also seeking to further understand how social inequality relates to the utilization of different channels and corresponding health outcomes. PMID:25616853

  14. Multi-Channel Electroencephalogram (EEG Signal Acquisition and its Effective Channel selection with De-noising Using AWICA for Biometric System

    Directory of Open Access Journals (Sweden)

    B.Sabarigiri

    2014-05-01

    Full Text Available the embedding of low cost electroencephalogram (EEG sensors in wireless headsets gives improved authentication based on their brain wave signals has become a practical opportunity. In this paper signal acquisition along with effective multi-channel selection from a specific area of the brain and denoising using AWICA methods are proposed for EEG based personal identification. At this point, to develop identification system the steps are as follows. (i the high-quality device with the least numbers of channels are essential for the EEG signal acquisition and Selecting the equipment and verdict the best portions on the scalp is the primary step. (ii Scrutiny of the acquired EEG signals and de-noising from EMG, ECG, EOG Signals and power line artifacts using AWICA (iii Obtain the features from the Enhanced EEG signals by Wavelet Transform (WT and LS-SVM Classification in the MATLAB Environment. Based on the outcome, there is possibility for implementation of an EEG based Practical biometric system.

  15. Language Control in Bilinguals: Monitoring and Response Selection.

    Science.gov (United States)

    Branzi, Francesca M; Della Rosa, Pasquale A; Canini, Matteo; Costa, Albert; Abutalebi, Jubin

    2016-06-01

    Language control refers to the cognitive mechanism that allows bilinguals to correctly speak in one language avoiding interference from the nontarget language. Bilinguals achieve this feat by engaging brain areas closely related to cognitive control. However, 2 questions still await resolution: whether this network is differently engaged when controlling nonlinguistic representations, and whether this network is differently engaged when control is exerted upon a restricted set of lexical representations that were previously used (i.e., local control) as opposed to control of the entire language system (i.e., global control). In the present event-related functional magnetic resonance imaging study, we investigated these 2 questions by employing linguistic and nonlinguistic blocked switching tasks in the same bilingual participants. We first report that the left prefrontal cortex is driven similarly for control of linguistic and nonlinguistic representations, suggesting its domain-general role in the implementation of response selection. Second, we propose that language control in bilinguals is hierarchically organized with the dorsal anterior cingulate cortex/presupplementary motor area acting as the supervisory attentional system, recruited for increased monitoring demands such as local control in the second language. On the other hand, prefrontal, inferior parietal areas and the caudate would act as the response selection system, tailored for language selection for both local and global control. PMID:25838037

  16. Island Formation through Bar Deposition and Channel Cutoff in the Bedrock Controlled South River, Virginia

    Science.gov (United States)

    Jurk, D.; Pizzuto, J. E.

    2010-12-01

    Islands in braided and meandering alluvial channels form by bar accretion and channel cutoff, however, island formation in bedrock-controlled channels is poorly understood. The South River is a single-thread, sinuous, gravel-bed, bedrock river. It is neither meandering nor braided but aerial photographs show the development of gravel bars and the formation of islands that have formed through channel cutoff. This study deciphers processes that lead to both types of island formation and their role in the channel morphology of the South River. The South River was analyzed using aerial photographs and work in the field provided additional data that were used to identify islands and their properties. A Geographic Information System (GIS) was used to evaluate historical aerial photographs dating back to 1937 for location, morphology, origin, and development of islands along an approximately 40 km study reach. Field studies included the surveying of cross sections to determine elevations of islands relative to neighboring floodplains, as well as pebble counts and cores to define sediment characteristics. Aerial photographs indicate that six islands had formed before and an additional 12 islands formed after 1937, placing the average island formation frequency at 0.005 islands per km per year since 1937. Field data indicate that elevation, grain size, stratigraphy, and vegetation of some islands closely resemble those of the floodplains supporting the hypothesis that those islands formed through cutoff, while one island’s sediment was similar to that of the channel and did not show similarities to floodplains or any other islands indicating formation through in-channel sediment deposition. Studies of bank erosion rates along the South River demonstrate that 33% of bank erosion along the South River occurs in divided reaches of the channel associated with islands. Understanding the formation and evolution of these islands may allow for an accurate prediction of future

  17. Control of colloid transport via solute gradients in dead-end channels

    Science.gov (United States)

    Shin, Sangwoo; Um, Eujin; Warren, Patrick; Stone, Howard

    2015-11-01

    Transport of colloids in dead-end channels is involved in widespread applications ranging from drug delivery to geophysical flows. In such geometries, Brownian motion may be considered as the sole mechanism that enables transport of colloidal particles into or out of the channels, which is, unfortunately, an extremely inefficient transport mechanism for microscale particles. Here, we explore the possibility of diffusiophoresis as a means to control the colloid transport by introducing a solute gradient along the dead-end channels. We demonstrate that the transport of colloidal particles into the dead-end channels can be either enhanced or completely prevented via diffusiophoresis. We also observe a size-dependent focusing of the particles where, as the particle size increases, the particles tend to concentrate more, and they tend to reside deeper in the channel. Our findings have implications for all manners of controlled release processes, especially for site-specific drug delivery systems where localized targeting of drugs with minimal dispersion to the non-target is essential.

  18. The design of multi-channel pulse amplitude analyzer based on ARM micro controller

    International Nuclear Information System (INIS)

    It introduces the design of multi-channel pulse amplitude analyzer based on embedded ARM micro-controller. The embedded and real-time system μC/OS-II builds up the real-time and stability of the system and advances the integration. (authors)

  19. ControlTree: Navigating and Selecting in a Large Tree

    OpenAIRE

    Appert, Caroline; Fekete, Jean-Daniel

    2006-01-01

    International audience We introduce ControlTree, a novel interface using crossing interaction to navigate and select nodes in a large tree. ControlTree combines an optimized dynamic layout with interaction features to quickly reach a node in a node-link tree representation.

  20. Adaptive antenna selection and Tx/Rx beamforming for large-scale MIMO systems in 60 GHz channels

    Directory of Open Access Journals (Sweden)

    Prasad Narayan

    2011-01-01

    Full Text Available Abstract We consider a large-scale MIMO system operating in the 60 GHz band employing beamforming for high-speed data transmission. We assume that the number of RF chains is smaller than the number of antennas, which motivates the use of antenna selection to exploit the beamforming gain afforded by the large-scale antenna array. However, the system constraint that at the receiver, only a linear combination of the receive antenna outputs is available, which together with the large dimension of the MIMO system makes it challenging to devise an efficient antenna selection algorithm. By exploiting the strong line-of-sight property of the 60 GHz channels, we propose an iterative antenna selection algorithm based on discrete stochastic approximation that can quickly lock onto a near-optimal antenna subset. Moreover, given a selected antenna subset, we propose an adaptive transmit and receive beamforming algorithm based on the stochastic gradient method that makes use of a low-rate feedback channel to inform the transmitter about the selected beams. Simulation results show that both the proposed antenna selection and the adaptive beamforming techniques exhibit fast convergence and near-optimal performance.

  1. Controlled release of stored optical pulses in an atomic ensemble into two separate photonic channels

    International Nuclear Information System (INIS)

    We report an experiment in which optical pulses stored in an atomic system can be controllably released into two different photonic channels. By controllably turning on the retrieve control pulses at either 795 or 780 nm to read the stored optical pulses in a four-level double Λ-type atomic medium, we can obtain the released probe pulse at 795 or 780 nm, respectively. These readout pulses can be further separated spatially and directed into different optical propagation channels through a grating. Such controlled release of stored optical pulses may extend the capabilities of the quantum information storage technique, and can have applications in multichannel all-optical switching, all-optical routing, quantum information processing, and image storage systems

  2. (-)-Englerin A is a potent and selective activator of TRPC4 and TRPC5 calcium channels.

    Science.gov (United States)

    Akbulut, Yasemin; Gaunt, Hannah J; Muraki, Katsuhiko; Ludlow, Melanie J; Amer, Mohamed S; Bruns, Alexander; Vasudev, Naveen S; Radtke, Lea; Willot, Matthieu; Hahn, Sven; Seitz, Tobias; Ziegler, Slava; Christmann, Mathias; Beech, David J; Waldmann, Herbert

    2015-03-16

    Current therapies for common types of cancer such as renal cell cancer are often ineffective and unspecific, and novel pharmacological targets and approaches are in high demand. Here we show the unexpected possibility for the rapid and selective killing of renal cancer cells through activation of calcium-permeable nonselective transient receptor potential canonical (TRPC) calcium channels by the sesquiterpene (-)-englerin A. This compound was found to be a highly efficient, fast-acting, potent, selective, and direct stimulator of TRPC4 and TRPC5 channels. TRPC4/5 activation through a high-affinity extracellular (-)-englerin A binding site may open up novel opportunities for drug discovery aimed at renal cancer. PMID:25707820

  3. 49 CFR 236.13 - Spring switch; selection of signal control circuits through circuit controller.

    Science.gov (United States)

    2010-10-01

    ... circuits through circuit controller. 236.13 Section 236.13 Transportation Other Regulations Relating to...; selection of signal control circuits through circuit controller. The control circuits of signals governing... circuit controller, or through the contacts of relay repeating the position of such circuit...

  4. How Much Feedback Is Required for TDD Multi-Antenna Broadcast Channels with User Selection?

    Directory of Open Access Journals (Sweden)

    Salim Umer

    2010-01-01

    Full Text Available The enormous gains in a multi-antenna transmitter broadcast channel require the Channel State Information at the Transmitter (CSIT. Although the fundamental question "How much feedback is required for a broadcast channel?" has been treated in the literature to some extent, a more comprehensive treatment is certainly desirable. We study the time-division duplex broadcast channel with initial assumption of channel state information (CSI neither at the base station (BS nor at the users' side. We provide two transmission strategies through which the BS and the users get necessary CSI. We derive novel lower and upper bounds for the sum rate reflecting the rate loss compared to a perfect CSIT system. Corresponding approximate sum rate expressions are also developed for both schemes. These expressions fully capture the benefits of the CSIT feedback, allowing multi-user diversity gain and better inter-user interference cancellation, and the cost of exchange of information required. These expressions can be optimized for any set of system parameters to unveil the trade-off between the cost and the gains associated to feedback. Thus they allow to characterize the optimal amount of feedback which maximizes the sum rate of the broadcast channel, a well-accepted metric of system performance at the physical layer.

  5. Universal design of BESIII slow control and selection of software

    International Nuclear Information System (INIS)

    This article expatiates the importance of Slow Control System in BESIII during the project BEPCII. And introduces the design of universal blue print of Slow Control, construction of computer system and principle of software selection in Slow Control System. As prefabrication of BESIII, we have finished the multi-embranchment environment monitoring system in BESII. In the system, so far the configuration software Controx2000 runs well. (authors)

  6. Selection of an efficient power supply and heat dissipation of multi-channel power amplifiers in APAA

    OpenAIRE

    Chukhmanov, V. V.

    2015-01-01

    When increasing a range of radar with an active phased antenna array (APAA) it is needed to generate pulses of increased power. To solve this problem, we use the multi-channel power amplifiers (MCPA) with extreme power levels under certain restrictions. Their practical implementation in radar is determined by an appropriate selection of efficient power supply and heat dissipation of the output transistors. From a variety of component units and products, as well as from constructive and techno...

  7. Novel control channel quality improvement in satellite communication systems employing high coding gain FEC

    Science.gov (United States)

    Morikura, Masahiro; Kubota, Shuji; Enomoto, Kiyoshi; Kato, Shuzo

    The authors propose a novel control channel quality improvement scheme for satellite communication systems using a majority decision method over convolutional coding and Viterbi decoding channels. To improve majority decision performance, which is degraded by burst errors due to Viterbi decoding in conventional serial transmission methods, a parallel transmission method is proposed. The performance of the parallel and serial transmission methods has been analyzed, and experiments have been carried out using rate-1/2 convolutional encoding and Viterbi decoding (constraint length 4 and 7). It is shown that the parallel transmission method has about 1010 times lower block-error performance at Pe = 1 x 10-4 than the conventional method.

  8. Nonlinear Control of Tunneling Through an Epsilon-Near-Zero Channel

    CERN Document Server

    Powell, David A; Edwards, Brian; Vakil, Ashkan; Kivshar, Yuri S; Engheta, Nader

    2009-01-01

    The epsilon-near-zero (ENZ) tunneling phenomenon allows full transmission of waves through a narrow channel even in the presence of a strong geometric mismatch. Here we experimentally demonstrate nonlinear control of the ENZ tunneling by an external field, as well as self-modulation of the transmission resonance due to the incident wave. Using a waveguide section near cut-off frequency as the ENZ system, we introduce a diode with tunable and nonlinear capacitance to demonstrate both of these effects. Our results confirm earlier theoretical ideas on using an ENZ channel for dielectric sensing, and their potential applications for tunable slow-light structures.

  9. A single point mutation in the pore region of the epithelial Na+ channel changes ion selectivity by modifying molecular sieving

    OpenAIRE

    Kellenberger, Stephan; Gautschi, Ivan; Schild, Laurent

    1999-01-01

    The epithelial Na+ channel (ENaC) belongs to a new class of channel proteins called the ENaC/DEG superfamily involved in epithelial Na+ transport, mechanotransduction, and neurotransmission. The role of ENaC in Na+ homeostasis and in the control of blood pressure has been demonstrated recently by the identification of mutations in ENaC β and γ subunits causing hypertension. The function of ENaC in Na+ reabsorption depends critically on its ability to discriminate between Na+ and other ions li...

  10. Bit Error Rate Performance Analysis of a Threshold-Based Generalized Selection Combining Scheme in Nakagami Fading Channels

    Directory of Open Access Journals (Sweden)

    Sulyman Ahmed Iyanda

    2005-01-01

    Full Text Available The severity of fading on mobile communication channels calls for the combining of multiple diversity sources to achieve acceptable error rate performance. Traditional approaches perform the combining of the different diversity sources using either the conventional selective diversity combining (CSC, equal-gain combining (EGC, or maximal-ratio combining (MRC schemes. CSC and MRC are the two extremes of compromise between performance quality and complexity. Some researches have proposed a generalized selection combining scheme (GSC that combines the best M branches out of the L available diversity resources (M ≤ L . In this paper, we analyze a generalized selection combining scheme based on a threshold criterion rather than a fixed-size subset of the best channels. In this scheme, only those diversity branches whose energy levels are above a specified threshold are combined. Closed-form analytical solutions for the BER performances of this scheme over Nakagami fading channels are derived. We also discuss the merits of this scheme over GSC.

  11. Control of mesoscopic transport by modifying transmission channels in opaque media

    Science.gov (United States)

    Sarma, Raktim; Yamilov, Alexey; Liew, Seng Fatt; Guy, Mikhael; Cao, Hui

    2015-12-01

    While controlling particle diffusion in a confined geometry is a popular approach taken by both natural and artificial systems, it has not been widely adopted for controlling light transport in random media, where wave interference effects play a critical role. The transmission eigenchannels determine not only light propagation through the disordered system but also the energy concentrated inside. Here, we propose and demonstrate an effective approach to modify these channels, whose structures are considered to be universal in conventional diffusive waveguides. By adjusting the waveguide geometry, we are able to alter the spatial profiles of the transmission eigenchannels significantly and deterministically from the universal ones. In addition, evanescent channels may be converted to propagating channels by gradually increasing the waveguide cross-section. Our approach allows to control not only the transmitted and reflected light, but also the depth profile of energy density inside the scattering system. In particular geometries, perfect reflection channels are created, and their large penetration depth into the turbid medium as well as the complete return of probe light to the input end would greatly benefit sensing and imaging applications. Absorption along with geometry can be further employed for tuning the decay length of energy flux inside the random system, which cannot be achieved in a common waveguide with uniform cross-section. Our approach relies solely on confined geometry and does not require any modification of intrinsic disorder, thus it is applicable to a variety of systems and also to other types of waves.

  12. Mechanisms of atrial-selective block of Na+ channels by ranolazine: I. Experimental analysis of the use-dependent block

    OpenAIRE

    Zygmunt, Andrew C.; Nesterenko, Vladislav V.; Rajamani, Sridharan; Hu, Dan; Barajas-Martinez, Hector; Belardinelli, Luiz; Antzelevitch, Charles

    2011-01-01

    Atrial-selective inhibition of cardiac Na+ channel current (INa) and INa-dependent parameters has been shown to contribute to the safe and effective management of atrial fibrillation. The present study examined the basis for the atrial-selective actions of ranolazine. Whole cell INa was recorded at 15°C in canine atrial and ventricular myocytes and in human embryonic kidney (HEK)-293 cells expressing SCN5A. Tonic block was negligible at holding potentials from −140 to −100 mV, suggesting mini...

  13. Changes in cationic selectivity of the nicotinic channel at the rat ganglionic synapse: a role for chloride ions?

    Directory of Open Access Journals (Sweden)

    Oscar Sacchi

    Full Text Available The permeability of the nicotinic channel (nAChR at the ganglionic synapse has been examined, in the intact rat superior cervical ganglion in vitro, by fitting the Goldman current equation to the synaptic current (EPSC I-V relationship. Subsynaptic nAChRs, activated by neurally-released acetylcholine (ACh, were thus analyzed in an intact environment as natively expressed by the mature sympathetic neuron. Postsynaptic neuron hyperpolarization (from -40 to -90 mV resulted in a change of the synaptic potassium/sodium permeability ratio (P(K/P(Na from 1.40 to 0.92, corresponding to a reversible shift of the apparent acetylcholine equilibrium potential, E(ACh, by about +10 mV. The effect was accompanied by a decrease of the peak synaptic conductance (g(syn and of the EPSC decay time constant. Reduction of [Cl(-](o to 18 mM resulted in a change of P(K/P(Na from 1.57 (control to 2.26, associated with a reversible shift of E(ACh by about -10 mV. Application of 200 nM αBgTx evoked P(K/P(Na and g(syn modifications similar to those observed in reduced [Cl(-](o. The two treatments were overlapping and complementary, as if the same site/mechanism were involved. The difference current before and after chloride reduction or toxin application exhibited a strongly positive equilibrium potential, which could not be explained by the block of a calcium component of the EPSC. Observations under current-clamp conditions suggest that the driving force modification of the EPSC due to P(K/P(Na changes represent an additional powerful integrative mechanism of neuron behavior. A possible role for chloride ions is suggested: the nAChR selectivity was actually reduced by increased chloride gradient (membrane hyperpolarization, while it was increased, moving towards a channel preferentially permeable for potassium, when the chloride gradient was reduced.

  14. Quality control and quality assurance plan for bridge channel-stability assessments in Massachusetts

    Science.gov (United States)

    Parker, Gene W.; Pinson, Harlow

    1993-01-01

    A quality control and quality assurance plan has been implemented as part of the Massachusetts bridge scour and channel-stability assessment program. This program is being conducted by the U.S. Geological Survey, Massachusetts-Rhode Island District, in cooperation with the Massachusetts Highway Department. Project personnel training, data-integrity verification, and new data-management technologies are being utilized in the channel-stability assessment process to improve current data-collection and management techniques. An automated data-collection procedure has been implemented to standardize channel-stability assessments on a regular basis within the State. An object-oriented data structure and new image management tools are used to produce a data base enabling management of multiple data object classes. Data will be reviewed by assessors and data base managers before being merged into a master bridge-scour data base, which includes automated data-verification routines.

  15. Automatic control of neutron flux in experimental channels of the WWR-M type reactors

    International Nuclear Information System (INIS)

    The flowsheet of the neutron flux local regulator intended for maintaining the given level of neutron flux distribution in experimental channels of the WWR-M type reactor under stationary and transition modes, is suggested. The functional diagram of the electron regulation block (ERB) in considered. The regulator is tested when the reactor operates with the capacity of 13 MWt along with the staff system of automated regulation and without it. The experiments carried out demonstrate the stable operation of the entire control system and good performance characteristics of the ERR block. The conclusion is made that the suggested method of neutron flux automated regulation in experimental channels can be successfully extended to a higher number of experimental channels and applied at other research reactors. Small size fission chambers and direct charging detectors can be used in local systems as sensors

  16. Tityus bahiensis toxin IV-5b selectively affects Na channel inactivation in chick dorsal root ganglion neurons.

    Science.gov (United States)

    Trequattrini, C; Zamudio, F Z; Petris, A; Prestipino, G; Possani, L D; Franciolini, F

    1995-09-01

    A novel toxin was isolated from the venom of the Brazilian scorpion Tityus (T.) bahiensis. The N-terminal amino acid sequence of this toxin was shown to be 80% identical to the corresponding segment of T. serrulatus toxin IV-5. The new toxin was thus named toxin IV-5b. Toxin IV-5b was found to markedly slow inactivation of Na channel in dorsal root ganglion neurons from chick embryo. By contrast, Na channel activation was only negligibly delayed, and deactivation completely unaffected. Similarly unaffected by the toxin were K and Ca currents. The slowing effect of the toxin starts to appear at concentrations of c. 80 nM, and shows a KD of 143 nM. With a toxin concentration of 2.4 microM, the Na channel inactivation time constant was increased c. 3-fold with respect to the control. The slowing of inactivation was voltage dependent, and increased with depolarization. PMID:7553331

  17. Clonal Selection Algorithm Based Iterative Learning Control with Random Disturbance

    Directory of Open Access Journals (Sweden)

    Yuanyuan Ju

    2013-01-01

    Full Text Available Clonal selection algorithm is improved and proposed as a method to solve optimization problems in iterative learning control. And a clonal selection algorithm based optimal iterative learning control algorithm with random disturbance is proposed. In the algorithm, at the same time, the size of the search space is decreased and the convergence speed of the algorithm is increased. In addition a model modifying device is used in the algorithm to cope with the uncertainty in the plant model. In addition a model is used in the algorithm cope with the uncertainty in the plant model. Simulations show that the convergence speed is satisfactory regardless of whether or not the plant model is precise nonlinear plants. The simulation test verify the controlled system with random disturbance can reached to stability by using improved iterative learning control law but not the traditional control law.

  18. Selective data collection in vehicular networks for traffic control applications

    CERN Document Server

    Płaczek, Bartłomiej

    2011-01-01

    Vehicular sensor network (VSN) is an emerging technology, which combines wireless communication offered by vehicular ad hoc networks (VANET) with sensing devices installed in vehicles. VSN creates a huge opportunity to extend the road-side sensor infrastructure of existing traffic control systems. The efficient use of the wireless communication medium is one of the basic issues in VSN applications development. This paper introduces a novel method of selective data collection for traffic control applications, which provides a significant reduction in data amounts transmitted through VSN. The underlying idea is to detect the necessity of data transfers on the basis of uncertainty determination of the traffic control decisions. According to the proposed approach, sensor data are transmitted from vehicles to the control node only at selected time moments. Data collected in VSN are processed using on-line traffic simulation technique, which enables traffic flow prediction, performance evaluation of control strateg...

  19. The selectivity, voltage-dependence and acid sensitivity of the tandem pore potassium channel TASK-1: contributions of the pore domains

    OpenAIRE

    Yuill, KH; Stansfeld, PJ; Ashmole, I; Sutcliffe, MJ; Stanfield, PR

    2007-01-01

    We have investigated the contribution to ionic selectivity of residues in the selectivity filter and pore helices of the P1 and P2 domains in the acid sensitive potassium channel TASK-1. We used site directed mutagenesis and electrophysiological studies, assisted by structural models built through computational methods. We have measured selectivity in channels expressed in Xenopus oocytes, using voltage clamp to measure shifts in reversal potential and current amplitudes when Rb+ or Na+ repla...

  20. In pursuit of small molecule chemistry for calcium-permeable non-selective TRPC channels -- mirage or pot of gold?

    Science.gov (United States)

    Bon, Robin S; Beech, David J

    2013-10-01

    The primary purpose of this review is to address the progress towards small molecule modulators of human Transient Receptor Potential Canonical proteins (TRPC1, TRPC3, TRPC4, TRPC5, TRPC6 and TRPC7). These proteins generate channels for calcium and sodium ion entry. They are relevant to many mammalian cell types including acinar gland cells, adipocytes, astrocytes, cardiac myocytes, cochlea hair cells, endothelial cells, epithelial cells, fibroblasts, hepatocytes, keratinocytes, leukocytes, mast cells, mesangial cells, neurones, osteoblasts, osteoclasts, platelets, podocytes, smooth muscle cells, skeletal muscle and tumour cells. There are broad-ranging positive roles of the channels in cell adhesion, migration, proliferation, survival and turning, vascular permeability, hypertrophy, wound-healing, hypo-adiponectinaemia, angiogenesis, neointimal hyperplasia, oedema, thrombosis, muscle endurance, lung hyper-responsiveness, glomerular filtration, gastrointestinal motility, pancreatitis, seizure, innate fear, motor coordination, saliva secretion, mast cell degranulation, cancer cell drug resistance, survival after myocardial infarction, efferocytosis, hypo-matrix metalloproteinase, vasoconstriction and vasodilatation. Known small molecule stimulators of the channels include hyperforin, genistein and rosiglitazone, but there is more progress with inhibitors, some of which have promising potency and selectivity. The inhibitors include 2-aminoethoxydiphenyl borate, 2-aminoquinolines, 2-aminothiazoles, fatty acids, isothiourea derivatives, naphthalene sulfonamides, N-phenylanthranilic acids, phenylethylimidazoles, piperazine/piperidine analogues, polyphenols, pyrazoles and steroids. A few of these agents are starting to be useful as tools for determining the physiological and pathophysiological functions of TRPC channels. We suggest that the pursuit of small molecule modulators for TRPC channels is important but that it requires substantial additional effort and

  1. Bypass Selection for Control of Heat Exchanger Network

    Institute of Scientific and Technical Information of China (English)

    SUN Lin; LUO Xionglin; HOU Benquan; BAI Yujie

    2013-01-01

    Considering the flexibility and controllability of heat exchanger networks (HENs),bypasses are widely used for effective control of process stream target temperatures.However,the optimal location for the bypass is generally difficult to design with the trade-off between controllability and capital investments.In this paper,based on the steady-state model of heat exchanger networks the optimal bypass location was firstly selected by iteratively calculating the non-square Relative Gain Array (ns-RGA).To simplify the calculation process,rules of bypass selection were also proposed.In order to evaluate this method,then,the structural controllability of heat exchanger networks was analyzed.With both the consideration of the controllability and capital investments,the bypasses locations were finally selected.A case study on the HEN in Crude Distillation Unit was presented in which the ns-RGA and structural controllability were used to select bypasses and also to evaluate the results.

  2. Marketing channels and control the distribution of products in the meat industry.

    OpenAIRE

    Sidorchuk, Roman

    2010-01-01

    The article deals with the formation of distribution channels in the meat industry. Question of finding channels. Awareness of the problem-added customer value in the channel. The task of shaping the company's own distribution channel products. The procedure of forming a channel of distribution. The main problem in forming their own distribution channel. Prospects of development of different channels

  3. Catchment- and reach-scale controls on the distribution and expectation of geomorphic channel adjustment

    Science.gov (United States)

    Lisenby, Peyton E.; Fryirs, Kirstie A.

    2016-05-01

    Variability in channel function (behavior) can be assessed by characterizing different forms of adjustment over time. Here, historical channel adjustments in three tributary systems of the Lockyer Valley, Southeast Queensland (SEQ) are analyzed in order to evaluate the range of catchment- and reach-scale controls on channel behavior. Over 300 individual adjustments and 13 forms of adjustment were identified over a ˜130 year time span. We measured the width-to-depth ratio (W:D), mean stream power (ω), and basin area (A) at the location of all observed adjustments. The most common forms of adjustment were avulsions, lateral expansion of the channel, and bend adjustments. The tributary systems behave distinctly different from one another according to statistical comparisons between the W:D, ω, and A data for these forms of adjustment. We find that it is possible to develop process domains or typologies for forms of geomorphic adjustment found in the Lockyer Valley. These domains or typologies provide the foundations for synoptic comparisons between catchments and assessing the expectation of channel adjustment (forecasting), which should be included in process-based river management practice.

  4. Digital remote control system for power supplies of particle channel magnetooptical elements

    International Nuclear Information System (INIS)

    Current control of magnetooptical elements of accelerator particle channels is based on control of reference voltage of current stabilizers. Advent of industrial multidigit (12 bits) integral analog-to-digital converters permitted to develop simple digital sources of reference voltage. A digital control system of 30 spatially remoted power supplies of magnetooptical elements of particle channels on the basis of the ''Elektronika-60'' microcomputer is described. The microcomputer is connected by the standard communication line (20 mA) with the SM-4 computer. The ''Summa'' crate is connected with the microcomputer through the branch driver. Digit data are transmitted by the multibranch trunk of sequential communication (Manchester-2 code) at the rate of 0.5 Mband. Feedback was realized by connection of analog signals through the distributed commutator to the measuring line with a digital voltmeter

  5. A distinct sodium channel voltage-sensor locus determines insect selectivity of the spider toxin Dc1a

    Science.gov (United States)

    Bende, Niraj S.; Dziemborowicz, Sławomir; Mobli, Mehdi; Herzig, Volker; Gilchrist, John; Wagner, Jordan; Nicholson, Graham M.; King, Glenn F.; Bosmans, Frank

    2014-07-01

    β-Diguetoxin-Dc1a (Dc1a) is a toxin from the desert bush spider Diguetia canities that incapacitates insects at concentrations that are non-toxic to mammals. Dc1a promotes opening of German cockroach voltage-gated sodium (Nav) channels (BgNav1), whereas human Nav channels are insensitive. Here, by transplanting commonly targeted S3b-S4 paddle motifs within BgNav1 voltage sensors into Kv2.1, we find that Dc1a interacts with the domain II voltage sensor. In contrast, Dc1a has little effect on sodium currents mediated by PaNav1 channels from the American cockroach even though their domain II paddle motifs are identical. When exploring regions responsible for PaNav1 resistance to Dc1a, we identified two residues within the BgNav1 domain II S1-S2 loop that when mutated to their PaNav1 counterparts drastically reduce toxin susceptibility. Overall, our results reveal a distinct region within insect Nav channels that helps determine Dc1a sensitivity, a concept that will be valuable for the design of insect-selective insecticides.

  6. Investigating the Effects of the Common Control Channel Challenge in Multichannel Cognitive Networks With Hypothetical Spectrum Hole

    Directory of Open Access Journals (Sweden)

    Mthulisi Velempini

    2013-11-01

    Full Text Available Multichannel MAC protocols have become a design choice of wireless access networks as they increase theachievable throughput. However, the implementationof a common control channel has been a challenge.The common control channel challenge has not been investigated in opportunistic networks where theavailability of medium is temporary and unpredictable. The uncertainty of the availability of the channelcoupled with the common control channel challenge makes this area an interesting research topic.Unfortunately, this challenge requires further investigation in Cognitive Radio Ad Hoc Networks(CRAHN, a promising next generation technology. The challenge makes an interesting study in CRAHNgiven the opportunistic access and use of channels.Given a hypothetical spectrum hole of any size coupledwith the implementation of a control channel in a multi-channel environment, how much of good put canberealized and be effectively utilized for data transmission. We investigate the common control channelchallenge in CRAHN through network simulations. Theopportunistic nature of CRAHNs in the presence ofthe common control channel challenge is investigated. The simulation results show that the combinationofthe control channel challenge and the size of the spectrum hole degrade gracefully the network.Furthermore, the size of the spectrum hole has a bearing on good put. The results show that a big holeimproves performance. Unfortunately, the opportunistic attribute of CRAHNs does not guarantee desirablespectrum holes.

  7. Variable structure control for MRAC systems with perturbations in input and output channels

    Institute of Scientific and Technical Information of China (English)

    武玉强[1; 余星火[2; 冯纯伯[3

    2000-01-01

    A design scheme of variable structure model reference control systems using only input and output measurements is presented for the systems with unmodeled dynamics and disturbances in input and output channels. The modeled part of the systems has relative degree greater than one and unknown upper bound of degree. By introducing some auxiliary signals and normalized signals with memory functions and appropriate choice of controller parameters, the developed variable structure controller guarantees the global stability of the closed-loop system and the arbitrarily small tracking error.

  8. Pulse selection control for the IR FEL photocathode drive laser

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, K.; Evans, R.; Garza, O. [and others

    1997-08-01

    The method for current control of a photocathode source is described. This system allows for full remote control of a photocathode drive laser for resulting electron beam currents ranging from less than one microamp to a full current ranging from less than one microamp to a full current of five milliamps. All current modes are obtained by gating the drive laser with a series of electro-optical cells. The system remotely generates this control signal by assuming a mode of operation with the following properties selectable: Current mode as continuous or gated, micropulse density, macropulse gate width from single shot to 1ms duration, macropulse synchronization to A/C line voltage (60 Hz) or an external trigger, 60 Hz phase and slewing through 60 Hz when applicable. All selections are derived from programmable logic devices operating from a master-oscillator resulting in a discrete, phase stable, pulse control for the drive laser.

  9. Whether and How to Select Inertia and Acceleration of Discrete Particle Swarm Optimization Algorithm: A Study on Channel Assignment

    Directory of Open Access Journals (Sweden)

    Min Jin

    2014-01-01

    Full Text Available There is recently a great deal of interest and excitement in understanding the role of inertia and acceleration in the motion equation of discrete particle swarm optimization (DPSO algorithms. It still remains unknown whether the inertia section should be abandoned and how to select the appropriate acceleration in order for DPSO to show the best convergence performance. Adopting channel assignment as a case study, this paper systematically conducts experimental filtering research on this issue. Compared with other channel assignment schemes, the proposed scheme and the selection of inertia and acceleration are verified to have the advantage to channel assignment in three respects of convergence rate, convergence speed, and the independency of the quality of initial solution. Furthermore, the experimental result implies that DSPO might have the best convergence performance when its motion equation includes an inertia section in a less medium weight, a bigger acceleration coefficient for global-search optimum, and a smaller acceleration coefficient for individual-search optimum.

  10. On the performance of arbitrary transmit selection for threshold-based receive MRC with and without co-channel interference

    KAUST Repository

    Radaydeh, Redha Mahmoud Mesleh

    2011-11-01

    The performance of multiple-antenna diversity systems in which the receiver combines signal replicas per threshold-based maximal ratio combining (MRC) and transmitter uses only a single antenna according to receive combined signal strength is studied. The impact of imperfect channel estimation and the effect of phase and time misalignments between desired and undesired signals are implicitly investigated. It is assumed that the desired signal replicas and interfering signals undergo statistically independent flat Rayleigh fading. The analysis is applicable for arbitrary transmit antenna selection, based either on receive combined signal-to-noise ratio (SNR) or receive combined signal-to-interference-plus-noise ratio (SINR). For the scenario of identical multiple-antenna channels, closed-form analytical results for the combined SNR statistics and some performance measures are first presented. The SNR-based and SINR-based selection algorithms are then employed to obtain expressions for the distribution of combined SINR and outage probability performance, which are applicable for different statistical models of interfering signals. The adopted system models herein as well as the analytical development add enhancements on many existing results, and can be used to study the performance of different architectures under various channel conditions when the implementation complexity is of interest. © 2011 IEEE.

  11. Selection bias: neighbourhood controls and controls selected from those presenting to a Health Unit in a case control study of efficacy of BCG revaccination

    Directory of Open Access Journals (Sweden)

    de Souza Wayner V

    2007-02-01

    Full Text Available Abstract Background In most case control studies the hardest decision is the choice of the control group, as in the ideal control group the proportion exposed is the same as in the population that produced the cases. Methods A comparison of two control groups in a case control study of the efficacy of BCG revaccination. One group was selected from subjects presenting to the heath unit the case attended for routine prevention and care; the second group was selected from the neighbourhood of cases. All Health Units from which controls were selected offered BCG revaccination. Efficacy estimated in a randomized control trial of BCG revaccination was used to establish that the neighbourhood control group was the one that gave unbiased results. Results The proportion of controls with scars indicating BCG revaccination was higher among the control group selected from Health Unit attenders than among neighbourhood controls. This excess was not removed after control for social variables and history of exposure to tuberculosis, and appears to have resulted from the fact that people attending the Health Unit were more likely to have been revaccinated than neighbourhood controls, although we can not exclude an effect of other unmeasured variables. Conclusion In this study, controls selected from people presenting to a Health Unit overrepresented exposure to BCG revaccination. Had the results from the HU attenders control group been accepted this would have resulted in overestimation of vaccine efficacy. When the exposure of interest is offered in a health facility, selection of controls from attenders at the facility may result in over representation of exposure in controls and selection bias.

  12. Vibrational excitons in ionophores: Experimental probes for quantum coherence-assisted ion transport and selectivity in ion channels

    CERN Document Server

    Ganim, Ziad; Vaziri, Alipasha

    2011-01-01

    Despite a large body of work, the exact molecular details underlying ion-selectivity and transport in the potassium channel have not been fully laid to rest. One major reason has been the lack of experimental methods that can probe these mechanisms dynamically on their biologically relevant time scales. Recently it was suggested that quantum coherence and its interplay with thermal vibration might be involved in mediating ion-selectivity and transport. In this work we present an experimental strategy for using time resolved infrared spectroscopy to investigate these effects. We show the feasibility by demonstrating the IR absorption and Raman spectroscopic signatures of potassium binding model molecules that mimic the transient interactions of potassium with binding sites of the selectivity filter during ion conduction. In addition to guide our experiments on the real system we have performed molecular dynamic-based simulations of the FTIR and 2DIR spectra of the entire KcsA complex, which is the largest comp...

  13. Control structure selection for energy integrated distillation column

    DEFF Research Database (Denmark)

    Hansen, J.E.; Jørgensen, Sten Bay

    1998-01-01

    This paper treats a case study on control structure selection for an almost binary distillation column. The column is energy integrated with a heat pump in order to transfer heat from the condenser to the reboiler. This integrated plant configuration renders the possible control structures somewhat...... determine the best structure in terms disturbance rejection and setpoint tracking. The pairing and controller design are implemented and evaluated through nonlinear simulation. The suggested control structure is also qualitatively compared to a control structure applied experimentally. (C) 1998 Elsevier...... different from what is usual for binary distillation columns. Further the heat pump enables disturbances to propagate faster through the system. The plant has six possible actuators of which three must be used to stabilize the system. Hereby three actuators are left for product purity control. An MILP...

  14. High-efficient photo-electron transport channel in SiC constructed by depositing cocatalysts selectively on specific surface sites for visible-light H2 production

    Science.gov (United States)

    Wang, Da; Peng, Yuan; Wang, Qi; Pan, Nanyan; Guo, Zhongnan; Yuan, Wenxia

    2016-04-01

    Control cocatalyst location on a metal-free semiconductor to promote surface charge transfer for decreasing the electron-hole recombination is crucial for enhancing solar energy conversion. Based on the findings that some metals have an affinity for bonding with the specific atoms of polar semiconductors at a heterostructure interface, we herein control Pt deposition selectively on the Si sites of a micro-SiC photocatalyst surface via in-situ photo-depositing. The Pt-Si bond forming on the interface constructs an excellent channel, which is responsible for accelerating photo-electron transfer from SiC to Pt and then reducing water under visible-light. The hydrogen production is enhanced by two orders of magnitude higher than that of bare SiC, and 2.5 times higher than that of random-depositing nano-Pt with the same loading amount.

  15. Description and control of dissociation channels in gas-phase protein complexes

    Science.gov (United States)

    Thachuk, Mark; Fegan, Sarah K.; Raheem, Nigare

    2016-08-01

    Using molecular dynamics simulations of a coarse-grained model of the charged apo-hemoglobin protein complex, this work expands upon our initial report [S. K. Fegan and M. Thachuk, J. Am. Soc. Mass Spectrom. 25, 722-728 (2014)] about control of dissociation channels in the gas phase using specially designed charge tags. Employing a charge hopping algorithm and a range of temperatures, a variety of dissociation channels are found for activated gas-phase protein complexes. At low temperatures, a single monomer unfolds and becomes charge enriched. At higher temperatures, two additional channels open: (i) two monomers unfold and charge enrich and (ii) two monomers compete for unfolding with one eventually dominating and the other reattaching to the complex. At even higher temperatures, other more complex dissociation channels open with three or more monomers competing for unfolding. A model charge tag with five sites is specially designed to either attract or exclude charges. By attaching this tag to the N-terminus of specific monomers, the unfolding of those monomers can be decidedly enhanced or suppressed. In other words, using charge tags to direct the motion of charges in a protein complex provides a mechanism for controlling dissociation. This technique could be used in mass spectrometry experiments to direct forces at specific attachment points in a protein complex, and hence increase the diversity of product channels available for quantitative analysis. In turn, this could provide insight into the function of the protein complex in its native biological environment. From a dynamics perspective, this system provides an interesting example of cooperative behaviour involving motions with differing time scales.

  16. Efficient multicast data transfer with congestion control using dynamic source channels

    OpenAIRE

    Lucas, Vincent; Pansiot, Jean-Jacques; Grad, Dominique; Hilt, Benoît

    2010-01-01

    The most efficient receiver-driven multicast congestion control protocols use dynamic channels. This means that each group has a cyclic rate variation with a continuously decreasing phase. Despite promising results in terms of fairness, using efficiently these dynamic groups could be a challenging task for application programmers. This paper presents a sequencer which maps out application data to dynamic groups in an optimal way. Multiple applications such as file transfer or video streaming,...

  17. Non-cooperative Feedback Rate Control Game for Channel State Information in Wireless Networks

    OpenAIRE

    Song, Lingyang; Han, Zhu; Zhang, Zhongshan; Jiao, Bingli

    2011-01-01

    It has been well recognized that channel state information (CSI) feedback is of great importance for dowlink transmissions of closed-loop wireless networks. However, the existing work typically researched the CSI feedback problem for each individual mobile station (MS), and thus, cannot efficiently model the interactions among self-interested mobile users in the network level. To this end, in this paper, we propose an alternative approach to investigate the CSI feedback rate control problem i...

  18. Unfolding of a Temperature-Sensitive Domain Controls Voltage-Gated Channel Activation.

    Science.gov (United States)

    Arrigoni, Cristina; Rohaim, Ahmed; Shaya, David; Findeisen, Felix; Stein, Richard A; Nurva, Shailika Reddy; Mishra, Smriti; Mchaourab, Hassane S; Minor, Daniel L

    2016-02-25

    Voltage-gated ion channels (VGICs) are outfitted with diverse cytoplasmic domains that impact function. To examine how such elements may affect VGIC behavior, we addressed how the bacterial voltage-gated sodium channel (BacNa(V)) C-terminal cytoplasmic domain (CTD) affects function. Our studies show that the BacNa(V) CTD exerts a profound influence on gating through a temperature-dependent unfolding transition in a discrete cytoplasmic domain, the neck domain, proximal to the pore. Structural and functional studies establish that the BacNa(V) CTD comprises a bi-partite four-helix bundle that bears an unusual hydrophilic core whose integrity is central to the unfolding mechanism and that couples directly to the channel activation gate. Together, our findings define a general principle for how the widespread four-helix bundle cytoplasmic domain architecture can control VGIC responses, uncover a mechanism underlying the diverse BacNa(V) voltage dependencies, and demonstrate that a discrete domain can encode the temperature-dependent response of a channel. PMID:26919429

  19. Ion slowing down and charge exchange at small impact parameters selected by channeling: superdensity effects

    OpenAIRE

    L'Hoir, A.; Adoui, A.; Barrué, F.; Billebaud, A.; Bosch, F.; Bräuning-Demian, A.; Bräuning, H.; Cassimi, A.; Chevallier, M.; C. Cohen; Dauvergne, D; Demonchy, C.E.; Giot, L.; Kirsch, R.; Gumberidze, A

    2005-01-01

    In two experiments performed with 20-30 MeV/u highly charged heavy ions (Pb56+, U91+) channeled through thin silicon crystals, we observed the original features of superdensity, associated to the glancing collisions with atomic rows undergone by part of the incident projectiles. In particular the very high collision rate yields a quite specific charge exchange regime, that leads to a higher ionization probability than in random conditions. X-ray measurements show that electrons captured in ou...

  20. Selected topics from the single top t-channel: cross section and other properties

    CERN Document Server

    Maier, Benedikt

    2016-01-01

    Measurements of the cross section and of the interactions happening at the tWb vertext are performed in the single top t-channel at center-of-mass energies of 7 and 8 TeV. Results of both ATLAS and CMS collaborations are presented. No indications for new physics and no deviations from the Standard Model predictions within the experimental and theoretical uncertainties are found.

  1. Selected topics from single top t-channel (XS and other properties)

    CERN Document Server

    Maier, Benedikt

    2015-01-01

    Measurements of the cross section and of the interactions happening at the tWb vertext are performed in the single top $t$-channel at center-of-mass energies of $\\sqrt{s}=7$ and $8$\\,TeV. Results of both ATLAS and CMS collaborations are presented. No indications for new physics and no deviations from the Standard Model predictions within the experimental and theoretical uncertainties are found.

  2. Resource-Based and Institutional Perspectives on Export Channel Selection and Export Performance

    OpenAIRE

    He, X; Brouthers, K. D.; Filatotchev, I.

    2012-01-01

    Exporting is a critically important strategy for firms to grow, yet research in this area has tended to ignore how firms can leverage resource-based capabilities to improve export performance. Building on the resource-based view and institutional theory, the authors develop a novel perspective to explain how a firm can improve export performance by aligning its export channel with its level of market orientation capabilities, contingent on the institutional distance between home and export ma...

  3. Capacity bounds for kth best path selection over generalized fading channels

    KAUST Repository

    Hanif, Muhammad Fainan

    2014-02-01

    Exact ergodic capacity calculation for fading wireless channels typically involves time-consuming numerical evaluation of infinite integrals. In this paper, lower and upper bounds on ergodic capacity for kth best path are presented. These bounds have simple analytic expressions which allow their fast evaluation. Numerical results show that the newly proposed bounds closely approximate the exact ergodic capacity for a large variety of system configurations. © 1997-2012 IEEE.

  4. Multi-Feedback Interference Cancellation Algorithms for OFDM Systems over Doubly-Selective Channels

    Directory of Open Access Journals (Sweden)

    Peng Li

    2015-07-01

    Full Text Available Orthogonal frequency-division multiplexing (OFDM systems over rapidly time varying channels may suffer from significant inter-carrier interference (ICI, which destroys the orthogonality between subcarriers and degrades the detection performance. Without sufficient ICI suppression, OFDM systems usually experience an error floor. According to the approximate matched filter bound (AMFB, the error floor in a coded OFDM system is not irreducible. In this work, we introduce novel multiple feedback matched filter (MBMF-based ICI cancellation receivers. Based on the output of a novel MBMF scheme, the approach employs a multiple ICI cancellation strategy with or without signal-to-interference-plus-noise-ratio (SINR ordering. The developed schemes can significantly improve the performance and remove the error floor with a negligible complexity increase. Given the multiple cancellation approach, we compare the SINR performance of the MBMF outputs with that employing single feedback and show that the SINR performance with multiple cancellation candidates is improved over that with a single one at practical SNR values. Additionally, for time-varying channels, we exploit partial fast Fourier transform (PFFT by splitting one OFDM symbol into multiple segments; the channel state is separately estimated by least-squares (LS methods without inserting more pilots. Simulation results demonstrate the superiority of the proposed methods over serial and block equalizers and the robustness to the Doppler effects compared to conventional single-segment method.

  5. Attitude Control of a Single Tilt Tri-Rotor UAV System: Dynamic Modeling and Each Channel's Nonlinear Controllers Design

    Directory of Open Access Journals (Sweden)

    Juing-Shian Chiou

    2013-01-01

    Full Text Available This paper has implemented nonlinear control strategy for the single tilt tri-rotor aerial robot. Based on Newton-Euler’s laws, the linear and nonlinear mathematical models of tri-rotor UAVs are obtained. A numerical analysis using Newton-Raphson method is chosen for finding hovering equilibrium point. Back-stepping nonlinear controller design is based on constructing Lyapunov candidate function for closed-loop system. By imitating the linguistic logic of human thought, fuzzy logic controllers (FLCs are designed based on control rules and membership functions, which are much less rigid than the calculations computers generally perform. Effectiveness of the controllers design scheme is shown through nonlinear simulation model on each channel.

  6. Photodissociation of the carbon monoxide dication in the 3Σ− manifold: Quantum control simulation towards the C2+ + O channel

    International Nuclear Information System (INIS)

    The photodissociation and laser assisted dissociation of the carbon monoxide dication X3Π CO2+ into the 3Σ− states are investigated. Ab initio electronic structure calculations of the adiabatic potential energy curves, radial nonadiabatic couplings, and dipole moments for the X 3Π state are performed for 13 excited 3Σ− states of CO2+. The photodissociation cross section, calculated by time-dependent methods, shows that the C+ + O+ channels dominate the process in the studied energy range. The carbon monoxide dication CO2+ is an interesting candidate for control because it can be produced in a single, long lived, v = 0 vibrational state due to the instability of all the other excited vibrational states of the ground 3Π electronic state. In a spectral range of about 25 eV, perpendicular transition dipoles couple this 3Π state to a manifold of 3Σ− excited states leading to numerous C+ + O+ channels and a single C2+ + O channel. This unique channel is used as target for control calculations using local control theory. We illustrate the efficiency of this method in order to find a tailored electric field driving the photodissociation in a manifold of strongly interacting electronic states. The selected local pulses are then concatenated in a sequence inspired by the “laser distillation” strategy. Finally, the local pulse is compared with optimal control theory

  7. Developing a Comparative Docking Protocol for the Prediction of Peptide Selectivity Profiles: Investigation of Potassium Channel Toxins

    Directory of Open Access Journals (Sweden)

    Serdar Kuyucak

    2012-02-01

    Full Text Available During the development of selective peptides against highly homologous targets, a reliable tool is sought that can predict information on both mechanisms of binding and relative affinities. These tools must first be tested on known profiles before application on novel therapeutic candidates. We therefore present a comparative docking protocol in HADDOCK using critical motifs, and use it to “predict” the various selectivity profiles of several major αKTX scorpion toxin families versus Kv1.1, Kv1.2 and Kv1.3. By correlating results across toxins of similar profiles, a comprehensive set of functional residues can be identified. Reasonable models of channel-toxin interactions can be then drawn that are consistent with known affinity and mutagenesis. Without biological information on the interaction, HADDOCK reproduces mechanisms underlying the universal binding of αKTX-2 toxins, and Kv1.3 selectivity of αKTX-3 toxins. The addition of constraints encouraging the critical lysine insertion confirms these findings, and gives analogous explanations for other families, including models of partial pore-block in αKTX-6. While qualitatively informative, the HADDOCK scoring function is not yet sufficient for accurate affinity-ranking. False minima in low-affinity complexes often resemble true binding in high-affinity complexes, despite steric/conformational penalties apparent from visual inspection. This contamination significantly complicates energetic analysis, although it is usually possible to obtain correct ranking via careful interpretation of binding-well characteristics and elimination of false positives. Aside from adaptations to the broader potassium channel family, we suggest that this strategy of comparative docking can be extended to other channels of interest with known structure, especially in cases where a critical motif exists to improve docking effectiveness.

  8. Analyzing the trade-off between multiple memory controllers and memory channels on multi-core processor performance

    Energy Technology Data Exchange (ETDEWEB)

    Sancho Pitarch, Jose Carlos [Los Alamos National Laboratory; Kerbyson, Darren [Los Alamos National Laboratory; Lang, Mike [Los Alamos National Laboratory

    2010-01-01

    Increasing the core-count on current and future processors is posing critical challenges to the memory subsystem to efficiently handle concurrent memory requests. The current trend to cope with this challenge is to increase the number of memory channels available to the processor's memory controller. In this paper we investigate the effectiveness of this approach on the performance of parallel scientific applications. Specifically, we explore the trade-off between employing multiple memory channels per memory controller and the use of multiple memory controllers. Experiments conducted on two current state-of-the-art multicore processors, a 6-core AMD Istanbul and a 4-core Intel Nehalem-EP, for a wide range of production applications shows that there is a diminishing return when increasing the number of memory channels per memory controller. In addition, we show that this performance degradation can be efficiently addressed by increasing the ratio of memory controllers to channels while keeping the number of memory channels constant. Significant performance improvements can be achieved in this scheme, up to 28%, in the case of using two memory controllers with each with one channel compared with one controller with two memory channels.

  9. Equivalence of Linear MMSE Detection in DS-CDMA and MC-CDMA Systems over Time and Frequency Selective Channels

    OpenAIRE

    Tamer A. Kadous; Sayeed, Akbar M.

    2003-01-01

    The goal of this paper is to compare the performance of the linear minimum mean square error (MMSE) detector for a class of code division multiple access (CDMA) systems in time and frequency selective channels. Specifically, we consider direct sequence (DS)-CDMA, multicarrier (MC)-CDMA, and the MC-DS-CDMA systems. Two key tools are used in our development. First, a general time-frequency framework that includes the different CDMA systems as special cases. Second, the duality between time and...

  10. Reactivity effects from voiding the fuel and control channels in RBMK as computed by a detailed three- dimensional model

    International Nuclear Information System (INIS)

    The RBMK core has a high degree of asymmetry, both, in its geometry and burn up. For a sufficiently accurate calculation a full scale 3-D model has to be used. for the Chernobylsk-3-3 reactor. The conditions evaluated included voiding the core and voiding the control channels. The major conclusion from the study is that the reactivity from voiding the control channels is much larger than voiding the entire core fuel channels. Since the core fuel channel voiding accident is much more probable and much faster than voiding the control channels, improvement were introduced into the reactor by adding additional full length absorbers and increasing the fuel enrichment. These improvement reduce significantly the reactivity contribution from the core voiding. (author). 4 refs., 3 tabs

  11. Selecting participants for listening tests of multi-channel reproduced sound

    DEFF Research Database (Denmark)

    Wickelmaier, Florian Maria; Choisel, Sylvain

    2005-01-01

    spatial hearing, and their verbal production abilities. The listeners displayed large individual differences in their performance. Forty subjects were selected based on the test results. The self-assessed listening habits and experience in the web-questionnaire could not predict the results of the......A selection procedure was devised in order to select listeners for experiments in which their main task will be to judge multichannel reproduced sound. Ninety-one participants filled in a web-based questionnaire. Seventy-eight of them took part in an assessment of their hearing thresholds, their...... selection procedure. Further, the hearing thresholds did not correlate with the spatial-hearing test. This leads to the conclusion that task-specific performance tests might be the preferable means of selecting a listening panel....

  12. Role of Kir4.1 channels in growth control of glia.

    Science.gov (United States)

    Higashimori, Haruki; Sontheimer, Harald

    2007-12-01

    The inwardly rectifying potassium channel Kir4.1 is widely expressed by astrocytes throughout the brain. Kir4.1 channels are absent in immature, proliferating glial cells. The progressive expression of Kir4.1 correlates with astrocyte differentiation and is characterized by the establishment of a negative membrane potential (> -70 mV) and an exit from the cell cycle. Despite some correlative evidence, a mechanistic interdependence between Kir4.1 expression, membrane hyperpolarization, and control of cell proliferation has not been demonstrated. To address this question, we used astrocyte-derived tumors (glioma) that lack functional Kir4.1 channels, and generated two glioma cell lines that stably express either AcGFP-tagged Kir4.1 channels or AcGFP vectors only. Kir4.1 expression confers the same K+ conductance to glioma membranes and a similar responsiveness to changes in [K+]o that characterizes differentiated astrocytes. Kir4.1 expression was sufficient to move the resting potential of gliomas from -50 to -80 mV. Importantly, Kir4.1 expression impaired cell growth by shifting a significant number of cells from the G2/M phase into the quiescent G0/G1 stage of the cell cycle. Furthermore, these effects could be nullified entirely if Kir4.1 channels were either pharmacologically inhibited by 100 microM BaCl2 or if cells were chronically depolarized by 20 mM KCl to the membrane voltage of growth competent glioma cells. These studies therefore demonstrate directly that Kir4.1 causes a membrane hyperpolarization that is sufficient to account for the growth attenuation, which in turn induces cell maturation characterized by a shift of the cells from G2/M into G0/G1. PMID:17876807

  13. Compact Hybrid Subsystem of 16 Channel Optical Demultiplexer, 2x2 Switches, Optical Power Monitors and Control Circuit

    Institute of Scientific and Technical Information of China (English)

    Kenichiro; Takahashi; Toshihiko; Kishimoto; Shintaro; Mouri; Youichi; Hata; Hideaki; Yusa; Mitsuaki; Tamura; Kazuhito; Saito; Hisao; Maki

    2003-01-01

    A compact hybrid subsystem of 16channel optical demultiplexer, 2x2 switches, optical power monitors and control circuit board is developed. The subsystem is able to add or drop arbitrary optical channels and monitor the optical power level by software commands. The size of the subsystem is 170x200x30(mm).

  14. Scheduling algorithm to select $k$ optimal programme slots in television channels: A graph theoretic approach

    OpenAIRE

    Pal, Madhumangal; Pal, Anita

    2014-01-01

    In this paper, it is shown that all programmes of all television channels can be modelled as an interval graph. The programme slots are taken as the vertices of the graph and if the time duration of two {programme slots} have non-empty intersection, the corresponding vertices are considered to be connected by an edge. The number of viewers of a programme is taken as the weight of the vertex. A set of programmes that are mutually exclusive in respect of time scheduling is called a session. We ...

  15. Cycle Time Reduction in Injection Molding Process by Selection of Robust Cooling Channel Design

    OpenAIRE

    Muhammad Khan; S. Kamran Afaq; Nizar Ullah Khan; Saboor Ahmad

    2014-01-01

    Cycle time of a part in injection molding process is very important as the rate of production and the quality of the parts produced depend on it, whereas the cycle time of a part can be reduced by reducing the cooling time which can only be achieved by the uniform temperature distribution in the molded part which helps in quick dissipation of heat. Conformal cooling channel design is the solution to the problem which basically “conforms” to the shape of cavity in the molds. This paper describ...

  16. Analysis of maximal-ratio of transmitting/receiving antenna selection with perfect and partial channel information

    Institute of Scientific and Technical Information of China (English)

    Xiao XIAO; Guangxi ZHU; Lin ZHOU; Desheng WANG; Li LI

    2008-01-01

    To improve system performance and reduce the complexity and cost of receiver hardware, we investi-gated a new multiple-input multiple-output (MIMO) scheme combining maximal-ratio transmitting and receiver antenna selection (MRT/RAS). In this scheme, a single receiving antenna, which maximizes the signal-to-noise ratio (SNR) at the receiver, is selected for demodulation. The closed-form outage probability and the bit error rate (BER) of the MRT/RAS system are both presented. The simulation demonstrates that the MRT/ RAS scheme can achieve a full diversity order as if all the receiving antennas were used. It is shown that the MRT/RAS scheme outperforms some more complex space-time codes of the same spectral efficiency. The ana-lytical results are verified by simulation. In the end, we also analyze the MRT/RAS system based on partial chan-nel information.

  17. Two-pulse laser control for selective photofragment orientation

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm

    1999-01-01

    The nuclear wave packet dynamics in the potential well of a bound molecule can be controlled by an intense infrared (IR)-laser pulse. The phase of the nuclear wave packet motion is shown to depend on the phase of the laser field and the initial orientation of the molecule. We demonstrate, for...... diatomic heteronuclear molecules, that these spatial effects can be used to control the angular distribution of photofragments by selective dissociation of molecules with a given initial orientation from a sample of randomly oriented molecules. (C) 1999 American Institute of Physics. [S0021-9606(99)01131-9]....

  18. CRSN轻量级信道选择算法%CRSN Lightweight Channel Selection Algorithm

    Institute of Scientific and Technical Information of China (English)

    傅宇; 余强; 余娜; 赵石真

    2015-01-01

    近年对认知无线电动态频谱接入技术研究基本上分为两类:频谱感知和基于概率预测,频谱感知直接获取物理层状态信息能更加准确,然而由于其算法一般较为复杂,能耗较高。提出一种轻量级算法,综合考虑信道及链路状态信息用以进行信道决策,仿真表明该算法在保持较低能耗的前提下提高系统的吞吐量,降低网络延迟。%In recent years, research on cognitive radio dynamic spectrum access technology is basically divided into two categories:spectrum sensing and probabilistic forecasting, spectrum sensing direct access to the physical layer status information is more accurate, because of their algorithm is generally more complex, higher energy consumption. Proposes a lightweight algorithm, considering the channel and link state information for decision-channel, simulation shows that the algorithm increases the throughput of the system reduces network latency under the premise of maintaining low power consumption.

  19. Post-selection technique for quantum channels with applications to quantum cryptography

    International Nuclear Information System (INIS)

    We propose a general method for studying properties of quantum channels acting on an n-partite system, whose action is invariant under permutations of the subsystems. Our main result is that, in order to prove that a certain property holds for any arbitrary input, it is sufficient to consider the special case where the input is a particular de Finetti-type state, i.e., a state which consists of n identical and independent copies of an (unknown) state on a single subsystem. A similar statement holds for more general channels which are covariant with respect to the action of an arbitrary finite or locally compact group. Our technique can be applied to the analysis of information-theoretic problems. For example, in quantum cryptography, we get a simple proof for the fact that security of a discrete-variable quantum key distribution protocol against collective attacks implies security of the protocol against the most general attacks. The resulting security bounds are tighter than previously known bounds obtained by proofs relying on the exponential de Finetti theorem

  20. Feedback Power Control Strategies inWireless Sensor Networks with Joint Channel Decoding

    Directory of Open Access Journals (Sweden)

    Fabio Perna

    2009-11-01

    Full Text Available In this paper, we derive feedback power control strategies for block-faded multiple access schemes with correlated sources and joint channel decoding (JCD. In particular, upon the derivation of the feasible signal-to-noise ratio (SNR region for the considered multiple access schemes, i.e., the multidimensional SNR region where error-free communications are, in principle, possible, two feedback power control strategies are proposed: (i a classical feedback power control strategy, which aims at equalizing all link SNRs at the access point (AP, and (ii an innovative optimized feedback power control strategy, which tries to make the network operational point fall in the feasible SNR region at the lowest overall transmit energy consumption. These strategies will be referred to as “balanced SNR” and “unbalanced SNR,” respectively. While they require, in principle, an unlimited power control range at the sources, we also propose practical versions with a limited power control range. We preliminary consider a scenario with orthogonal links and ideal feedback. Then, we analyze the robustness of the proposed power control strategies to possible non-idealities, in terms of residual multiple access interference and noisy feedback channels. Finally, we successfully apply the proposed feedback power control strategies to a limiting case of the class of considered multiple access schemes, namely a central estimating officer (CEO scenario, where the sensors observe noisy versions of a common binary information sequence and the AP’s goal is to estimate this sequence by properly fusing the soft-output information output by the JCD algorithm.

  1. An Improved Endmember Selection Method Based on Vector Length for MODIS Reflectance Channels

    OpenAIRE

    Yuanliu Xu; Jiancheng Shi; Jinyang Du

    2015-01-01

    Endmember selection is the basis for sub-pixel land cover classifications using multiple endmember spectral mixture analysis (MESMA) that adopts variant endmember matrices for each pixel to mitigate errors caused by endmember variability in SMA. A spectral library covering a large number of endmembers can account for endmember variability, but it also lowers the computational efficiency. Therefore, an efficient endmember selection scheme to optimize the library is crucial to implement MESMA....

  2. Improving Performance of Wi-Fi by Compact MIMO Systems by using Gama Frequency-Selective Fading Channels

    Directory of Open Access Journals (Sweden)

    Mr. Sudesh Gupta

    2011-09-01

    Full Text Available In this paper we propose a compact MIMO system in frequency-selective fading channels which improves the performance of Wireless Media. A MIMO beam forming system model with mutual coupling and matching network is proposed to cope with frequency-selective fading channels. The overall system proposed transfer matrix is derived using Z-parameter method. The system using the transform matrix which accepts the relay and the delay matrix for the computation. Then apply the diversity criteria by which we can make the code output pair which is distinct. So we can obtain two different pairs one is shows the below value in the MIMO System one is the Higher value. It is the only way to achieve orthogonally. One particular problem with this is that it has uneven power among the symbols it transmits. This means that the signal does not have a constant envelope and that the power each antenna must transmit has to vary, both of which are undesirable. We can take the middle value which overcomes this problem.

  3. Improving Performance of Wi-Fi by Compact MIMO Systems by using Gama Frequency-Selective Fading Channels

    Directory of Open Access Journals (Sweden)

    Sudesh Gupta

    2011-12-01

    Full Text Available In this paper we propose a compact MIMO system in frequency-selective fading channels which improves the performance of Wireless Media. A MIMO beam forming system model with mutual coupling and matching network is proposed to cope with frequency-selective fading channels. The overall system proposed transfer matrix is derived using Z-parameter method. The system using the transform matrix which accepts the relay and the delay matrix for the computation. Then apply the diversity criteria by which we can make the code output pair which is distinct. So we can obtain two different pairs one is shows the below value in the MIMO System one is the Higher value. It is the only way to achieve orthogonally. One particular problem with this is that it has uneven power among the symbols it transmits. This means that the signal does not have a constant envelope and that the power each antenna must transmit has to vary, both of which are undesirable. We can take the middle value which overcomes this problem.

  4. Performance analysis of selective cooperation in underlay cognitive networks over Rayleigh channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2011-06-01

    Underlay cognitive networks should follow strict interference thresholds to operate in parallel with primary networks. This constraint limits their transmission power and eventually the area of coverage. Therefore, it is very likely that the underlay networks will make use of relays to transmit signals to the distant secondary users. In this paper, we propose a secondary relay selection scheme which maximizes the end-to-end signal to noise ratio (SNR) for the secondary link while keeping the interference levels to the primary network below a certain threshold. We derive closed form expressions for the probability density function (PDF) of the SNR at the secondary destination, average bit error probability and outage probability. Analytical results are verified through simulations which also give insight about the benefits and tradeoffs of the selective cooperation in underlay cognitive networks. It is shown that, in contrast to non-cognitive selective cooperation, this scheme performs better in low SNR region for cognitive networks. © 2011 IEEE.

  5. Non-textured laser modification of silica glass surface: Wettability control and flow channel formation

    Science.gov (United States)

    Aono, Yuko; Hirata, Atsushi; Tokura, Hitoshi

    2016-05-01

    Local wettability of silica glass surface is modified by infrared laser irradiation. The silica glass surface exhibits hydrophobic property in the presence of sbnd CF3 or sbnd (CH3)2 terminal functional groups, which are decomposed by thermal treatment, and degree of the decomposition depends on the applied heat. Laser irradiation can control the number of remaining functional groups according to the irradiation conditions; the contact angle of deionized water on the laser modified surfaces range from 100° to 40°. XPS analysis confirms that the variation in wettability corresponds to the number of remaining sbnd CF3 groups. The laser irradiation achieves surface modification without causing any cracks or damages to the surface, as observed by SEM and AFM; moreover, surface transparency to visible light and surface roughness remains unaffected. The proposed method is applied to plane flow channel systems. Dropped water spreads only on the hydrophilic and invisible line modified by the laser irradiation without formation of any grooves. This indicates that the modified line can act as a surface channel. Furthermore, self-transportation of liquid is also demonstrated on a channel with gradually-varied wettability along its length. A water droplet on a hydrophobic side is self-transported to a hydrophilic side due to contact-angle hysteresis force without any actuators or external forces.

  6. Outage Performance Analysis of Relay Selection Schemes in Wireless Energy Harvesting Cooperative Networks over Non-Identical Rayleigh Fading Channels.

    Science.gov (United States)

    Do, Nhu Tri; Bao, Vo Nguyen Quoc; An, Beongku

    2016-01-01

    In this paper, we study relay selection in decode-and-forward wireless energy harvesting cooperative networks. In contrast to conventional cooperative networks, the relays harvest energy from the source's radio-frequency radiation and then use that energy to forward the source information. Considering power splitting receiver architecture used at relays to harvest energy, we are concerned with the performance of two popular relay selection schemes, namely, partial relay selection (PRS) scheme and optimal relay selection (ORS) scheme. In particular, we analyze the system performance in terms of outage probability (OP) over independent and non-identical (i.n.i.d.) Rayleigh fading channels. We derive the closed-form approximations for the system outage probabilities of both schemes and validate the analysis by the Monte-Carlo simulation. The numerical results provide comprehensive performance comparison between the PRS and ORS schemes and reveal the effect of wireless energy harvesting on the outage performances of both schemes. Additionally, we also show the advantages and drawbacks of the wireless energy harvesting cooperative networks and compare to the conventional cooperative networks. PMID:26927119

  7. Source and Channel Adaptive Rate Control for Multicast Layered Video Transmission Based on a Clustering Algorithm

    Directory of Open Access Journals (Sweden)

    Jérôme Viéron

    2004-03-01

    Full Text Available This paper introduces source-channel adaptive rate control (SARC, a new congestion control algorithm for layered video transmission in large multicast groups. In order to solve the well-known feedback implosion problem in large multicast groups, we first present a mechanism for filtering RTCP receiver reports sent from receivers to the whole session. The proposed filtering mechanism provides a classification of receivers according to a predefined similarity measure. An end-to-end source and FEC rate control based on this distributed feedback aggregation mechanism coupled with a video layered coding system is then described. The number of layers, their rate, and their levels of protection are adapted dynamically to aggregated feedbacks. The algorithms have been validated with the NS2 network simulator.

  8. Weed control and selectivity of flumioxazin in eucalyptus

    Directory of Open Access Journals (Sweden)

    Rafael Augusto Soares Tiburcio

    2012-12-01

    Full Text Available Flumioxazin is a registered herbicide for agricultural crops what is an important fact concerning integrated management for weeds in eucalyptus plantations. This study evaluated the efficiency of weed control and the phytotoxicity in eucalyptus plants caused by the herbicide flumioxazin applied alone or in tank mixture with sulfentrazone and isoxaflutole. The aim was to extend the use of thisherbicide in eucalyptus. The herbicide was applied to eucalyptus plants using precision backpack sprayer. It was evaluated, visually,the intoxication percentage and measured height and diameter of eucalyptus trees, the control plants and dry mass of weeds. It wasconcluded that flumioxazin is selective to the eucalyptus at the 125 g.ha-1 dosage, and its efficiency in controlling weeds pre-emergencewas better when mixed in the tank with isoxaflutole and sulfentrazone.

  9. Control by blowing of the separated flow in a channel with a stepwise expansion

    Czech Academy of Sciences Publication Activity Database

    Jonáš, Pavel; Mazur, Oton; Uruba, Václav

    Praha : UTAM AV ČR, 2006 - (Náprstek, J.; Fischer, C.), s. 148-149 ISBN 80-86246-27-2. [Engineering mechanics 2006 : national conference with international participation. Svratka (CZ), 15.05.2006-18.05.2006] R&D Projects: GA AV ČR(CZ) IAA200760614; GA ČR(CZ) GA101/03/0018 Institutional research plan: CEZ:AV0Z20760514 Keywords : backward facing step * flow control by blowing/suction * narrow channel flow Subject RIV: BK - Fluid Dynamics

  10. NUMERICAL MODELING OF CHANNEL EQUILIBRIUM PROFILE AND ITS EFFECT ON FLOOD CONTROL

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the morphology of Luoshan-Hankou reach at the middle Yangtze River, the one-dimensional, unsteady flow and sediment transport numerical model was adopted to study the generalized channel equilibrium profile. The variation of the longitudinal equilibrium profile, and the relation with the condition of the inflow water and sediment from the upper reach were analyzed. Meanwhile, the numerical simulation results were compared with the corresponding theoretical results. Finally, the equilibrium longitudinal slope variations and its impact on flood control were analyzed after the sediment transport process has changed.

  11. Fault-tolerant controlled quantum secure direct communication over a collective quantum noise channel

    International Nuclear Information System (INIS)

    This work proposes controlled quantum secure direct communication (CQSDC) over an ideal channel. Based on the proposed CQSDC, two fault-tolerant CQSDC protocols that are robust under two kinds of collective noises, collective-dephasing noise and collective-rotation noise, respectively, are constructed. Due to the use of quantum entanglement of the Bell state (or logical Bell state) as well as dense coding, the proposed protocols provide easier implementation as well as better qubit efficiency than other CQSDC protocols. Furthermore, the proposed protocols are also free from correlation-elicitation attack and other well-known attacks. (paper)

  12. Influence of different structured channels of mesoporous silicate on the controlled ibuprofen delivery

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Lin [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China); Sun, Jihong, E-mail: jhsun@bjut.edu.cn [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China); Zhang, Li; Wang, Jinpeng; Ren, Bo [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China)

    2012-08-15

    The bimodal mesoporous silicas with short random mesoporous channels and MCM-41 with long ordered mesopores were synthesised and modified with 3-(2-aminoethylamino) propyltrimethoxysilane as ibuprofen carriers to study the influence of mesoporous structure on drug delivery property. For further comparing the different mesoporous channels, modified SBA-15 with relative large and long ordered mesopores was also synthesized as drug carriers. The resultant samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, N{sub 2} adsorption-desorption isotherms, thermogravimetric analyses, solid-state {sup 29}Si NMR spectra, elemental analysis, and UV-vis spectra. Meanwhile, the Korsmeyer-Peppas equation f{sub t} = kt{sup n} was employed to analyze the drug release profile and three release mediums including simulated fluid solution, distilled water and simulated gastric fluid were used. The results indicated that the modified BMMs with the bimodal mesopores leaded to the most drug loading amount of 25.0 mg/0.1 g, while the MCM-41 with the long and one-dimensional mesopores had the least loading amount around 20.3 mg/0.1 g. Meanwhile, the easier diffusion behavior of drug molecules in the bimodal mesopore channels of BMMs resulted in relatively faster drug release properties in comparison with MCM-41, while the release time maintained in SBF for about 12 h (release percent was about 90 wt%) and corresponding release constant k obtained from Korsmeyer-Peppas equation was around 4.10. Highlights: Black-Right-Pointing-Pointer BMMs, MCM-41 and SBA-15 with different mesostructure channels were modified with amino groups via post-treatment procedure. Black-Right-Pointing-Pointer Loading and release profiles of ibuprofen in modified BMMs, MCM-41 and SBA-15. Black-Right-Pointing-Pointer BMMs presents more drug loading amount than MCM-41 as well as better controlled release than SBA-15.

  13. Digitally controlled high-performance dc SQUID readout electronics for a 304-channel vector magnetometer

    Science.gov (United States)

    Bechstein, S.; Petsche, F.; Scheiner, M.; Drung, D.; Thiel, F.; Schnabel, A.; Schurig, Th

    2006-06-01

    Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/√Hz was specially designed for a 304-channel low-Tc dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm × 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm × 4 cm × 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented.

  14. An Improved Endmember Selection Method Based on Vector Length for MODIS Reflectance Channels

    Directory of Open Access Journals (Sweden)

    Yuanliu Xu

    2015-05-01

    Full Text Available Endmember selection is the basis for sub-pixel land cover classifications using multiple endmember spectral mixture analysis (MESMA that adopts variant endmember matrices for each pixel to mitigate errors caused by endmember variability in SMA. A spectral library covering a large number of endmembers can account for endmember variability, but it also lowers the computational efficiency. Therefore, an efficient endmember selection scheme to optimize the library is crucial to implement MESMA. In this study, we present an endmember selection method based on vector length. The spectra of a land cover class were divided into subsets using vector length intervals of the spectra, and the representative endmembers were derived from these subsets. Compared with the available endmember average RMSE (EAR method, our approach improved the computational efficiency in endmember selection. The method accuracy was further evaluated using spectral libraries derived from the ground reference polygon and Moderate Resolution Imaging Spectroradiometer (MODIS imagery respectively. Results using the different spectral libraries indicated that MESMA combined with the new approach performed slightly better than EAR method, with Kappa coefficient improved from 0.75 to 0.78. A MODIS image was used to test the mapping fraction, and the representative spectra based on vector length successfully modeled more than 90% spectra of the MODIS pixels by 2-endmember models.

  15. The Scorpion Toxin Analogue BmKTX-D33H as a Potential Kv1.3 Channel-Selective Immunomodulator for Autoimmune Diseases.

    Science.gov (United States)

    Ye, Fang; Hu, Youtian; Yu, Weiwei; Xie, Zili; Hu, Jun; Cao, Zhijian; Li, Wenxin; Wu, Yingliang

    2016-01-01

    The Kv1.3 channel-acting scorpion toxins usually adopt the conserved anti-parallel β-sheet domain as the binding interface, but it remains challenging to discover some highly selective Kv1.3 channel-acting toxins. In this work, we investigated the pharmacological profile of the Kv1.3 channel-acting BmKTX-D33H, a structural analogue of the BmKTX scorpion toxin. Interestingly, BmKTX-D33H, with its conserved anti-parallel β-sheet domain as a Kv1.3 channel-interacting interface, exhibited more than 1000-fold selectivity towards the Kv1.3 channel as compared to other K⁺ channels (including Kv1.1, Kv1.2, Kv1.7, Kv11.1, KCa2.2, KCa2.3, and KCa3.1). As expected, BmKTX-D33H was found to inhibit the cytokine production and proliferation of both Jurkat cells and human T cells in vitro. It also significantly improved the delayed-type hypersensitivity (DTH) responses, an autoreactive T cell-mediated inflammation in rats. Amino acid sequence alignment and structural analysis strongly suggest that the "evolutionary" Gly11 residue of BmKTX-D33H interacts with the turret domain of Kv1 channels; it appears to be a pivotal amino acid residue with regard to the selectivity of BmKTX-D33H towards the Kv1.3 channel (in comparison with the highly homologous scorpion toxins). Together, our data indicate that BmKTX-D33H is a Kv1.3 channel-specific blocker. Finally, the remarkable selectivity of BmKTX-D33H highlights the great potential of evolutionary-guided peptide drug design in future studies. PMID:27104568

  16. Tutorial on Feedback Control of Flows, Part I: Stabilization of Fluid Flows in Channels and Pipes

    Directory of Open Access Journals (Sweden)

    Ole M. Aamo

    2002-07-01

    Full Text Available The field of flow control has picked up pace over the past decade or so, on the promise of real-time distributed control on turbulent scales being realizable in the near future. This promise is due to the micromachining technology that emerged in the 1980s and developed at an amazing speed through the 1990s. In lab experiments, so called micro-electro-mechanical systems (MEMS that incorporate the entire detection-decision-actuation process on a single chip, have been batch processed in large numbers and assembled into flexible skins for gluing onto body-fluid interfaces for drag reduction purposes. Control of fluid flows span a wide variety of specialities. In Part I of this tutorial, we focus on the problem of reducing drag in channel and pipe flows by stabilizing the parabolic equilibrium profile using boundary feedback control. The control strategics used for this problem include classical control, based on the Nyquist criteria, and various optimal control techniques (H2, H-Infinity, as well as applications of Lyapunov stability theory.

  17. Relaminarisation of Re_{\\tau} = 100 channel flow with globally stabilising linear feedback control

    CERN Document Server

    Sharma, A S; McKeon, B J; Limebeer, D J N L; Koberg, W H; Sherwin, S J; 10.1063/1.3662449

    2013-01-01

    The problems of nonlinearity and high dimension have so far prevented a complete solution of the control of turbulent flow. Addressing the problem of nonlinearity, we propose a flow control strategy which ensures that the energy of any perturbation to the target profile decays monotonically. The controller's estimate of the flow state is similarly guaranteed to converge to the true value. We present a one-time off-line synthesis procedure, which generalises to accommodate more restrictive actuation and sensing arrangements, with conditions for existence for the controller given in this case. The control is tested in turbulent channel flow ($Re_\\tau=100$) using full-domain sensing and actuation on the wall-normal velocity. Concentrated at the point of maximum inflection in the mean profile, the control directly counters the supply of turbulence energy arising from the interaction of the wall-normal perturbations with the flow shear. It is found that the control is only required for the larger-scale motions, sp...

  18. Selective inhibition of a slow-inactivating voltage-dependent K+ channel in rat PC12 cells by hypoxia.

    Science.gov (United States)

    Conforti, L; Millhorn, D E

    1997-07-15

    1. Electrophysiological (single-channel patch clamp) and molecular biological experiments (reverse transcriptase-polymerase chain reaction) were performed to attempt to identify the O2-sensitive K+ channel in rat phaeochromocytoma (PC12) cells. 2. Four types of K+ channels were recorded in PC12 cells: a small-conductance K+ channel (14 pS), a calcium-activated K+ channel (KCa; 102 pS) and two K+ channels with similar conductance (20 pS). These last two channels differed in their time-dependent inactivation: one was a slow-inactivating channel, while the other belonged to the family of fast transient K+ channels. 3. The slow-inactivating 20 pS K+ channel was inhibited by hypoxia. Exposure to hypoxia produced a 50% reduction in channel activity (number of active channels in the patch x open probability). Hypoxia had no effect on the 20 pS transient K+ channels, whereas reduced O2 stimulated the KCa channels. 4. The genes encoding the alpha-subunits of slow-inactivating K+ channels for two members of the Shaker subfamily of K+ channels (Kv1.2 and Kv1.3) together with the Kv2.1, Kv3.1 and Kv3.2 channel genes were identified in PC12 cells. 5. The expression of the Shaker Kv1.2, but none of the other K+ channel genes, increased in cells exposed to prolonged hypoxia (18 h). The same cells were more responsive to a subsequent exposure to hypoxia (35% inhibition of K+ current measured in whole-cell voltage clamp) compared with the cells maintained in normoxia (19% inhibition). 6. These results indicate that the O2-sensitive K+ channel in PC12 cells is a 20 pS slow-inactivating K+ channel that is upregulated by hypoxia. This channel appears to belong to the Shaker subfamily of voltage-gated K+ channels. PMID:9263911

  19. Implementing portable channel access server software in the KEKB accelerator control system

    International Nuclear Information System (INIS)

    KEKB (KEK B-factory) accelerators are under construction and the control computer system for them is also in the last phase of installation. KEKB accelerators are composed of two storage rings, namely, HER (High Energy Ring for electrons of 8 GeV) and LER (Low Energy Ring for positrons of 3.5 GeV). These rings are placed in the underground tunnel in which former TRISTAN electron-positron colliding accelerator was. We have been constructing control system for KEKB from the scratch based on EPICS (Experimental Physics and Industrial Control Systems). But, for the injector linac, its control computer system was rejuvenated just a few years ago and it is not an EPICS based system but an original one. To operate KEKB accelerators, tuning of the linac as the injector for the KEKB rings is thought to be very essential. Ideally, KEKB control system can control both KEKB rings and linac. And both operators at linac control room and at KEKB control room should be able to monitor and adjust equipment of the other accelerators. For that purpose, we have to develop suitable method in between two systems to communicate with each other. In the EPICS collaborations, there is a Portable CA (Channel Access) Server for EPICS developed at Los Alamos National Laboratory for SUN workstations. We decided to modify it for our purposes and have been implementing it to KEKB control system step by step. And now, we can monitor and set magnetic field of Q-magnets in the linac, control beam transport magnets in the linac beam line, control klystrons, and measure beam positions by strip-line monitors through EPICS. In the near future, other equipment of the linac will be added to the CA server before the commissioning of the KEKB rings. (author)

  20. Enhancement of hippocampal pyramidal cell excitability by the novel selective slow-afterhyperpolarization channel blocker 3-(triphenylmethylaminomethyl)pyridine (UCL2077).

    Science.gov (United States)

    Shah, Mala M; Javadzadeh-Tabatabaie, Mazyar; Benton, David C H; Ganellin, C Robin; Haylett, Dennis G

    2006-11-01

    The slow afterhyperpolarization (sAHP) in hippocampal neurons has been implicated in learning and memory. However, its precise role in cell excitability and central nervous system function has not been explicitly tested for 2 reasons: 1) there are, at present, no selective inhibitors that effectively reduce the underlying current in vivo or in intact in vitro tissue preparations, and 2) although it is known that a small conductance K(+) channel that activates after a rise in [Ca(2+)](i) underlies the sAHP, the exact molecular identity remains unknown. We show that 3-(triphenylmethylaminomethyl)pyridine (UCL2077), a novel compound, suppressed the sAHP present in hippocampal neurons in culture (IC(50) = 0.5 microM) and in the slice preparation (IC(50) approximately 10 microM). UCL2077 was selective, having minimal effects on Ca(2+) channels, action potentials, input resistance and the medium afterhyperpolarization. UCL2077 also had little effect on heterologously expressed small conductance Ca(2+)-activated K(+) (SK) channels. Moreover, UCL2077 and apamin, a selective SK channel blocker, affected spike firing in hippocampal neurons in different ways. These results provide further evidence that SK channels are unlikely to underlie the sAHP. This study also demonstrates that UCL2077, the most potent, selective sAHP blocker described so far, is a useful pharmacological tool for exploring the role of sAHP channels in the regulation of cell excitability in intact tissue preparations and, potentially, in vivo. PMID:16877678

  1. Interfacial electronic effects control the reaction selectivity of platinum catalysts

    Science.gov (United States)

    Chen, Guangxu; Xu, Chaofa; Huang, Xiaoqing; Ye, Jinyu; Gu, Lin; Li, Gang; Tang, Zichao; Wu, Binghui; Yang, Huayan; Zhao, Zipeng; Zhou, Zhiyou; Fu, Gang; Zheng, Nanfeng

    2016-05-01

    Tuning the electronic structure of heterogeneous metal catalysts has emerged as an effective strategy to optimize their catalytic activities. By preparing ethylenediamine-coated ultrathin platinum nanowires as a model catalyst, here we demonstrate an interfacial electronic effect induced by simple organic modifications to control the selectivity of metal nanocatalysts during catalytic hydrogenation. This we apply to produce thermodynamically unfavourable but industrially important compounds, with ultrathin platinum nanowires exhibiting an unexpectedly high selectivity for the production of N-hydroxylanilines, through the partial hydrogenation of nitroaromatics. Mechanistic studies reveal that the electron donation from ethylenediamine makes the surface of platinum nanowires highly electron rich. During catalysis, such an interfacial electronic effect makes the catalytic surface favour the adsorption of electron-deficient reactants over electron-rich substrates (that is, N-hydroxylanilines), thus preventing full hydrogenation. More importantly, this interfacial electronic effect, achieved through simple organic modifications, may now be used for the optimization of commercial platinum catalysts.

  2. Nerve compression activates selective nociceptive pathways and upregulates peripheral sodium channel expression in Schwann cells.

    Science.gov (United States)

    Frieboes, Laura Rummler; Palispis, Winnie Anne; Gupta, Ranjan

    2010-06-01

    Chronic nerve compression (CNC) injuries, such as carpal tunnel syndrome, are common musculoskeletal conditions that affect patients with debilitating loss of sensory function and pain. Although early detection and treatment are important, our understanding of pain-related molecular mechanisms remains largely unclear. Here we investigate these mechanisms using an animal model for CNC injury. To confirm that CNC injury induces pain, we assessed expression of c-fos, a gene that is rapidly expressed in spinal sensory afferents in response to painful peripheral stimuli, and TNF-alpha and IL-6, two proinflammatory cytokines that are crucial to development of inflammatory-mediated pain. Results show c-fos upregulation 1-2 weeks postinjury in the absence of TNF-alpha or IL-6 expression, indicating increased neural sensitivity without an inflammatory response. This is consistent with previous studies that showed no morphologic evidence of inflammation in the CNC model. Surprisingly, we also found de novo expression of Na(V)1.8, a sodium channel linked to the development of neuropathic pain, in endoneurial Schwann cells following injury. Until now, Na(V)1.8 expression was thought to be restricted to sensory neurons. CNC injury appears to be a unique model of noninflammatory neuropathic pain. Further investigation of the underlying molecular basis could yield promising targets for early diagnosis and treatment. PMID:20014316

  3. Mimo Based Downlink Channels with Limited Feedback and User Selection Using Th Precoding Technique

    Directory of Open Access Journals (Sweden)

    B.Muralidharan

    2014-03-01

    Full Text Available The implementation of Tomlinson-Harashima (TH pre-coding for multiuser MIMO systems based on quantized channel state information (CSI at the transmitter side. Compared with the results in [1], our scheme applies to more general system setting where the number of users in the system can be less than or equal to the number of transmit antennas. We also study the achievable average sum rate of the proposed quantized CSI-based TH pre-coding scheme. The expressions of the upper bounds on both the average sum rate of the systems with quantized CSI and the mean loss in average sum rate due to CSI quantization are derived. We also present some numerical results. The results show that the nonlinear TH pre-coding can achieve much better performance than that of linear zero-forcing pre-coding for both perfect CSI and quantized CSI cases. In addition, our derived upper bound on the mean rate loss for TH pre-coding converges to the true rate loss faster than that of zero-forcing pre-coding obtained in [2] as the number of feedback bits becomes large. Both the analytical and numerical results show that nonlinear pre-coding suffers from imperfect CSI more than linear pre-coding does.

  4. Abiotic controls of emergent macrophyte density in a bedrock channel - The Cahaba River, AL (USA)

    Science.gov (United States)

    Vaughn, Ryan S.; Davis, Lisa

    2015-10-01

    Research examining bedrock channels is growing. Despite this, biotic-abiotic interactions remain a topic mostly addressed in alluvial systems. This research identified hydrogeomorphic factors operating at the patch-scale (100-102 m) in bedrock shoals of the Cahaba River (AL) that help determine the distribution of the emergent aquatic macrophyte, Justicia americana. Macrophyte patch density (number of stems/m2) and percent bedrock void surface area (rock surface area/m2 occupied by joints, fractures, and potholes) were measured (n = 24 within two bedrock shoals) using stem counts and underwater photography, respectively. One-dimensional hydrologic modeling (HEC-RAS 4.1.0) was completed for a section within a shoal to examine velocity and channel depth as controlling variables for macrophyte patch density. Results from binary logistic regression analysis identified depth and velocity as good predictors of the presence or absence of Justicia americana within shoal structures (depth p = 0.001, velocity p = 0.007), which is a similar finding to previous research conducted in alluvial systems. Correlation analysis between bedrock surface void area and stem density demonstrated a statistically significant positive correlation (r = 0.665, p = 0.01), elucidating a link between abiotic-biotic processes that may well be unique to bedrock channels. These results suggest that the amount of void space present in bedrock surfaces, in addition to localized depth and velocity, helps control macrophyte patch density in bedrock shoal complexes. The utility of geomorphology in explaining patch-scale habitat heterogeneity in this study highlights geomorphology's potential to help understand macrophyte habitat heterogeneity at the reach scale, while also demonstrating its promise for mapping and understanding habitat heterogeneity at the system scale.

  5. Extended plasma channels created by UV laser in air and their application to control electric discharges

    International Nuclear Information System (INIS)

    Results are presented from a series of experimental and theoretical studies on creating weakly ionized extended plasma channels in atmospheric air by 248-nm UV laser radiation and their application to control long high-voltage discharges. The main mechanisms of air ionization by UV laser pulses with durations from 100 fs to 25 ns and intensities in the ranges of 3×1011–1.5×1013 and 3×106–3×1011 W/cm2, respectively, which are below the threshold for optical gas breakdown, as well as the main relaxation processes in plasma with a density of 109–1017 cm−3, are considered. It is shown that plasma channels in air can be efficiently created by amplitude-modulated UV pulses consisting of a train of subpicosecond pulses producing primary photoelectrons and a long UV pulse suppressing electron attachment and sustaining the density of free electrons in plasma. Different modes of the generation and amplification of trains of subterawatt subpicosecond pulses and amplitude-modulated UV pulses with an energy of several tens of joules were implemented on the GARPUN-MTW hybrid Ti:sapphire-KrF laser facility. The filamentation of such UV laser beams during their propagation in air over distances of up to 100 m and the parameters of the corresponding plasma channels were studied experimentally and theoretically. Laser initiation of high-voltage electric discharges and control of their trajectories by means of amplitude-modulated UV pulses, as well as the spatiotemporal structure of breakdowns in air gaps with length of up to 80 cm, were studied

  6. Control of neuronal ion channel function by glycogen synthase kinase-3: new prospective for an old kinase

    Directory of Open Access Journals (Sweden)

    Norelle Christine Wildburger

    2012-07-01

    Full Text Available Glycogen synthase kinase 3 (GSK-3 is an evolutionarily conserved multifaceted ubiquitous enzyme. In the central nervous system (CNS, GSK-3 acts through an intricate network of intracellular signaling pathways culminating in a highly divergent cascade of phosphorylations that control neuronal function during development and adulthood. Accumulated evidence indicates that altered levels of GSK-3 correlate with maladaptive plasticity of neuronal circuitries in psychiatric disorders, addictive behaviors, and neurodegenerative diseases, and pharmacological interventions known to limit GSK-3 can counteract some of these deficits. Thus, targeting the GSK-3 cascade for therapeutic interventions against this broad spectrum of brain diseases has raised a tremendous interest. Yet, the multitude of GSK-3 downstream effectors poses a substantial challenge in the development of selective and potent medications that could efficiently block or modulate the activity of this enzyme. Although the full range of GSK-3 molecular targets are far from resolved, exciting new evidence indicates that ion channels regulating excitability, neurotransmitter release, and synaptic transmission, which ultimately contribute to the mechanisms underling brain plasticity and higher level cognitive and emotional processing, are new promising targets of this enzyme. Here, we will revise this new emerging role of GSK-3 in controlling the activity of voltage-gated Na+, K+, Ca2+ channels and ligand-gated glutamate receptors with the goal of highlighting new relevant endpoints of the neuronal GSK-3 cascade that could provide a platform for a better understanding of the mechanisms underlying the dysfunction of this kinase in the CNS and serve as a guidance for medication development against the broad range of GSK-3-linked human diseases.

  7. Selection of material balance areas and item control areas

    International Nuclear Information System (INIS)

    Section 70.58, ''Fundamental Nuclear Material Controls,'' of 10 CFR Part 70, ''Special Nuclear Material,'' requires certain licensees authorized to possess more than one effective kilogram of special nuclear material to establish Material Balance Areas (MBAs) or Item Control Areas (ICAs) for the physical and administrative control of nuclear materials. This section requires that: (1) each MBA be an identifiable physical area such that the quantity of nuclear material being moved into or out of the MBA is represented by a measured value; (2) the number of MBAs be sufficient to localize nuclear material losses or thefts and identify the mechanisms; (3) the custody of all nuclear material within an MBA or ICA be the responsibility of a single designated individual; and (4) ICAs be established according to the same criteria as MBAs except that control into and out of such areas would be by item identity and count for previously determined special nuclear material quantities, the validity of which must be ensured by tamper-safing unless the items are sealed sources. This guide describes bases acceptable to the NRC staff for the selection of material balance areas and item control areas. (U.S.)

  8. Attosecond-recollision-controlled selective fragmentation of polyatomic molecules

    CERN Document Server

    Xie, Xinhua; Roither, Stefan; Schöffler, Markus S; Kartashov, Daniil; Xu, Huailiang; Rathje, Tim; Paulus, Gerhard G; Baltuška, Andrius; Gräfe, Stefanie; Kitzler, Markus

    2012-01-01

    Control over various fragmentation reactions of a series of polyatomic molecules (acetylene, ethylene, 1,3-butadiene) by the optical waveform of intense few-cycle laser pulses is demonstrated experimentally. We show both experimentally and theoretically that the responsible mechanism is inelastic ionization from inner-valence molecular orbitals by recolliding electron wavepackets, whose recollision energy in few-cycle ionizing laser pulses strongly depends on the optical waveform. Our work demonstrates an efficient and selective way of pre-determining fragmentation and isomerization reactions in polyatomic molecules on sub-femtosecond time-scales.

  9. Attosecond-recollision-controlled selective fragmentation of polyatomic molecules.

    Science.gov (United States)

    Xie, Xinhua; Doblhoff-Dier, Katharina; Roither, Stefan; Schöffler, Markus S; Kartashov, Daniil; Xu, Huailiang; Rathje, Tim; Paulus, Gerhard G; Baltuška, Andrius; Gräfe, Stefanie; Kitzler, Markus

    2012-12-14

    Control over various fragmentation reactions of a series of polyatomic molecules (acetylene, ethylene, 1,3-butadiene) by the optical waveform of intense few-cycle laser pulses is demonstrated experimentally. We show both experimentally and theoretically that the responsible mechanism is inelastic ionization from inner-valence molecular orbitals by recolliding electron wave packets, whose recollision energy in few-cycle ionizing laser pulses strongly depends on the optical waveform. Our work demonstrates an efficient and selective way of predetermining fragmentation and isomerization reactions in polyatomic molecules on subfemtosecond time scales. PMID:23368312

  10. Status of selected air pollution control programs, February 1992

    International Nuclear Information System (INIS)

    The collection of status reports has been prepared in order to provide a timely summary of selected EPA air pollution control activities to those individuals who are involved with the implementation of these programs. The report contains ozone/carbon monoxide (CO) programs; mobile sources programs; particulate matter nominally 10M and less (PM-10), sulfur dioxide (SO2) and lead programs; New Source Review (NSR); economics programs; emission standards programs; Indian activity programs; mobile sources programs; air toxics programs; acid rain programs; permits programs; chlorofluorocarbons programs; enforcement programs; and other programs

  11. Neural Network Model Based Cluster Head Selection for Power Control

    Directory of Open Access Journals (Sweden)

    Krishan Kumar

    2011-01-01

    Full Text Available Mobile ad-hoc network has challenge of the limited power to prolong the lifetime of the network, because power is a valuable resource in mobile ad-hoc network. The status of power consumption should be continuously monitored after network deployment. In this paper, we propose coverage aware neural network based power control routing with the objective of maximizing the network lifetime. Cluster head selection is proposed using adaptive learning in neural networks followed by coverage. The simulation results show that the proposed scheme can be used in wide area of applications in mobile ad-hoc network.

  12. Self-assembled oxide films with tailored nanoscale ionic and electronic channels for controlled resistive switching.

    Science.gov (United States)

    Cho, Seungho; Yun, Chao; Tappertzhofen, Stefan; Kursumovic, Ahmed; Lee, Shinbuhm; Lu, Ping; Jia, Quanxi; Fan, Meng; Jian, Jie; Wang, Haiyan; Hofmann, Stephan; MacManus-Driscoll, Judith L

    2016-01-01

    Resistive switches are non-volatile memory cells based on nano-ionic redox processes that offer energy efficient device architectures and open pathways to neuromorphics and cognitive computing. However, channel formation typically requires an irreversible, not well controlled electroforming process, giving difficulty to independently control ionic and electronic properties. The device performance is also limited by the incomplete understanding of the underlying mechanisms. Here, we report a novel memristive model material system based on self-assembled Sm-doped CeO2 and SrTiO3 films that allow the separate tailoring of nanoscale ionic and electronic channels at high density (∼10(12) inch(-2)). We systematically show that these devices allow precise engineering of the resistance states, thus enabling large on-off ratios and high reproducibility. The tunable structure presents an ideal platform to explore ionic and electronic mechanisms and we expect a wide potential impact also on other nascent technologies, ranging from ionic gating to micro-solid oxide fuel cells and neuromorphics. PMID:27491392

  13. Self-assembled oxide films with tailored nanoscale ionic and electronic channels for controlled resistive switching

    Science.gov (United States)

    Cho, Seungho; Yun, Chao; Tappertzhofen, Stefan; Kursumovic, Ahmed; Lee, Shinbuhm; Lu, Ping; Jia, Quanxi; Fan, Meng; Jian, Jie; Wang, Haiyan; Hofmann, Stephan; MacManus-Driscoll, Judith L.

    2016-08-01

    Resistive switches are non-volatile memory cells based on nano-ionic redox processes that offer energy efficient device architectures and open pathways to neuromorphics and cognitive computing. However, channel formation typically requires an irreversible, not well controlled electroforming process, giving difficulty to independently control ionic and electronic properties. The device performance is also limited by the incomplete understanding of the underlying mechanisms. Here, we report a novel memristive model material system based on self-assembled Sm-doped CeO2 and SrTiO3 films that allow the separate tailoring of nanoscale ionic and electronic channels at high density (~1012 inch-2). We systematically show that these devices allow precise engineering of the resistance states, thus enabling large on-off ratios and high reproducibility. The tunable structure presents an ideal platform to explore ionic and electronic mechanisms and we expect a wide potential impact also on other nascent technologies, ranging from ionic gating to micro-solid oxide fuel cells and neuromorphics.

  14. Energy-Efficient Power Control in Multipath CDMA Channels via Large System Analysis

    CERN Document Server

    Buzzi, Stefano; Poor, H Vincent

    2008-01-01

    This paper is focused on the design and analysis of power control procedures for the uplink of multipath code-division-multiple-access (CDMA) channels based on the large system analysis (LSA). Using the tools of LSA, a new decentralized power control algorithm aimed at energy efficiency maximization and requiring very little prior information on the interference background is proposed; moreover, it is also shown that LSA can be used to predict with good accuracy the performance and operational conditions of a large network operating at the equilibrium over a multipath channel, i.e. the power, signal-to-interference-plus-noise ratio (SINR) and utility profiles across users, wherein the utility is defined as the number of bits reliably delivered to the receiver for each energy-unit used for transmission. Additionally, an LSA-based performance comparison among linear receivers is carried out in terms of achieved energy efficiency at the equilibrium. Finally, the problem of the choice of the utility-maximizing tr...

  15. Self-assembled oxide films with tailored nanoscale ionic and electronic channels for controlled resistive switching

    Science.gov (United States)

    Cho, Seungho; Yun, Chao; Tappertzhofen, Stefan; Kursumovic, Ahmed; Lee, Shinbuhm; Lu, Ping; Jia, Quanxi; Fan, Meng; Jian, Jie; Wang, Haiyan; Hofmann, Stephan; MacManus-Driscoll, Judith L.

    2016-01-01

    Resistive switches are non-volatile memory cells based on nano-ionic redox processes that offer energy efficient device architectures and open pathways to neuromorphics and cognitive computing. However, channel formation typically requires an irreversible, not well controlled electroforming process, giving difficulty to independently control ionic and electronic properties. The device performance is also limited by the incomplete understanding of the underlying mechanisms. Here, we report a novel memristive model material system based on self-assembled Sm-doped CeO2 and SrTiO3 films that allow the separate tailoring of nanoscale ionic and electronic channels at high density (∼1012 inch−2). We systematically show that these devices allow precise engineering of the resistance states, thus enabling large on–off ratios and high reproducibility. The tunable structure presents an ideal platform to explore ionic and electronic mechanisms and we expect a wide potential impact also on other nascent technologies, ranging from ionic gating to micro-solid oxide fuel cells and neuromorphics. PMID:27491392

  16. Development of selective blockers for Ca2+-activated Cl- channel using Xenopus laevis oocytes with an improved drug screening strategy

    Directory of Open Access Journals (Sweden)

    Oh Soo-Jin

    2008-10-01

    Full Text Available Abstract Background Ca2+-activated Cl- channels (CaCCs participate in many important physiological processes. However, the lack of effective and selective blockers has hindered the study of these channels, mostly due to the lack of good assay system. Here, we have developed a reliable drug screening method for better blockers of CaCCs, using the endogeneous CaCCs in Xenopus laevis oocytes and two-electrode voltage-clamp (TEVC technique. Results Oocytes were prepared with a treatment of Ca2+ ionophore, which was followed by a treatment of thapsigargin which depletes Ca2+ stores to eliminate any contribution of Ca2+ release. TEVC was performed with micropipette containing chelerythrine to prevent PKC dependent run-up or run-down. Under these conditions, Ca2+-activated Cl- currents induced by bath application of Ca2+ to oocytes showed stable peak amplitude when repetitively activated, allowing us to test several concentrations of a test compound from one oocyte. Inhibitory activities of commercially available blockers and synthesized anthranilic acid derivatives were tested using this method. As a result, newly synthesized N-(4-trifluoromethylphenylanthranilic acid with trifluoromethyl group (-CF3 at para position on the benzene ring showed the lowest IC50. Conclusion Our results provide an optimal drug screening strategy suitable for high throughput screening, and propose N-(4-trifluoromethylphenylanthranilic acid as an improved CaCC blocker.

  17. ZD7288, a selective hyperpolarization-activated cyclic nucleotide-gated channel blocker, inhibits hippocampal synaptic plasticity

    Institute of Scientific and Technical Information of China (English)

    Xiao-xue Zhang; Xiao-chun Min; Xu-lin Xu; Min Zheng; Lian-jun Guo

    2016-01-01

    The selective hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker 4-(N-ethyl-N-phenylamino)-1,2-dimeth-yl-6-(methylamino) pyrimidinium chloride (ZD7288) blocks the induction of long-term potentiation in the perforant path–CA3 region in rat hippocampusin vivo. To explore the mechanisms underlying the action of ZD7288, we recorded excitatory postsynaptic potentials in perforant path–CA3 synapses in male Sprague-Dawley rats. We measured glutamate content in the hippocampus and in cultured hip-pocampal neurons using high performance liquid chromatography, and determined intracellular Ca2+ concentration ([Ca2+]i) using Fura-2. ZD7288 inhibited the induction and maintenance of long-term potentiation, and these effects were mirrored by the nonspeciifc HCN channel blocker cesium. ZD7288 also decreased glutamate release in hippocampal tissue and in cultured hippocampal neurons. Further-more, ZD7288 attenuated glutamate-induced rises in [Ca2+]i in a concentration-dependent manner and reversed 8-Br-cAMP-mediated facilitation of these glutamate-induced [Ca2+]i rises. Our results suggest that ZD7288 inhibits hippocampal synaptic plasticity both gluta-mate release and resultant [Ca2+]i increases in rat hippocampal neurons.

  18. Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor with Selective Analyte Channels and Graphene-Silver Deposited Core

    Directory of Open Access Journals (Sweden)

    Ahmmed A. Rifat

    2015-05-01

    Full Text Available We propose a surface plasmon resonance (SPR sensor based on photonic crystal fiber (PCF with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs. Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM. The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1 with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint.

  19. Evaluation of an in vitro cell assay to select attenuated bacterial mutants of Aeromonas hydrophila and Edwardsiella tarda to channel catfish

    Science.gov (United States)

    Both Aeromonas hydrophila (causative agent of motile aeromonas septicemia) and Edwardsiella tarda (causative agent of enteric septicemia) are Gram-negative bacteria widely distributed in aquatic environments, affecting many fish species worldwide, including channel catfish and tilapia. To control ba...

  20. An easy prepared dual-channel chemosensor for selective and instant detection of fluoride based on double Schiff-base.

    Science.gov (United States)

    Leng, Yan-Li; Zhang, Jian-Hui; Li, Qiao; Zhang, You-Ming; Lin, Qi; Yao, Hong; Wei, Tai-Bao

    2016-10-01

    A colorimetric and fluorescent dual-channel fluoride chemosensor N,N'-bis (4-diethylaminosalicylidene) hydrazine (sensor S) bearing two imine groups has been designed and synthesized. This structurally simple probe displays rapid response and high selectivity for fluoride over other common anions (Cl(-), Br(-), I(-), AcO(-), H2PO4(-), HSO4(-), ClO4(-), CN(-) and SCN(-)) in a highly polar aqueous DMSO solution. Mechanism studies suggested that the sensor firstly combined with F(-) through hydrogen bonds and then experienced the deprotonation process at higher concentrations of F(-) anion to the two Ar-OH groups. The detection limit was 5.78×10(-7)M of F(-), which points to the high detection sensitivity. Test strips based on sensor S were fabricated, which could act as a convenient and efficient F(-) test kit to detect F(-) for "in-the-field" measurement. PMID:27262660

  1. Dynamics of ions in the selectivity filter of the KcsA channel: Towards a coupled Brownian particle description

    CERN Document Server

    Cosseddu, Salvatore M; Allen, Michael P; Rodger, P M; Luchinsky, Dmitry G; McClintock, Peter V E

    2013-01-01

    The statistical and dynamical properties of ions in the selectivity filter of the KcsA ion channel are considered on the basis of molecular dynamics (MD) simulations of the KcsA protein embedded in a lipid membrane surrounded by an ionic solution. A new approach to the derivation of a Brownian dynamics (BD) model of ion permeation through the filter is discussed, based on unbiased MD simulations. It is shown that depending on additional assumptions, ion's dynamics can be described either by under-damped Langevin equation with constant damping and white noise or by Langevin equation with a fractional memory kernel. A comparison of the potential of the mean force derived from unbiased MD simulations with the potential produced by the umbrella sampling method demonstrates significant differences in these potentials. The origin of these differences is an open question that requires further clarifications.

  2. Dynamics of ions in the selectivity filter of the KcsA channel. Towards a coupled Brownian particle description

    Science.gov (United States)

    Cosseddu, S. M.; Khovanov, I. A.; Allen, M. P.; Rodger, P. M.; Luchinsky, D. G.; McClintock, P. V. E.

    2013-10-01

    The statistical and dynamical properties of ions in the selectivity filter of the KcsA ion channel are considered on the basis of molecular dynamics (MD) simulations of the KcsA protein embedded in a lipid membrane surrounded by an ionic solution. A new approach to the derivation of a Brownian dynamics (BD) model of ion permeation through the filter is discussed, based on unbiased MD simulations. It is shown that depending on additional assumptions, ion's dynamics can be described either by under-damped Langevin equation with constant damping and white noise or by Langevin equation with a fractional memory kernel. A comparison of the potential of the mean force derived from unbiased MD simulations with the potential produced by the umbrella sampling method demonstrates significant differences in these potentials. The origin of these differences is an open question that requires further clarifications.

  3. Selection of an optimized control nuclide to halt primary pumps

    International Nuclear Information System (INIS)

    Primary pumps are indispensable equipment to a nuclear power station. Besides maintaining the safe operation a unit, they play an un-replaceable function to control radiation source term. Selecting an optimized radionuclide to control the halt of primary pumps is an essential guide to deal with the problem between outage duration and reduction of radiation source term to a Pressurized Water Reactor (PWR) unit. From operational experiences of Daya Bay Nuclear Power Station (NPS), the author points out that 110mAg is the key nuclide which contributes largely to the radiation on the reactor unload/reload pool surface. The author also recommends a limit of 110mAg for halt of the primary pumps

  4. Joint random beam and spectrum selection for spectrum sharing systems with partial channel state information

    KAUST Repository

    Abdallah, Mohamed M.

    2013-11-01

    In this work, we develop joint interference-aware random beam and spectrum selection scheme that provide enhanced performance for the secondary network under the condition that the interference observed at the primary receiver is below a predetermined acceptable value. We consider a secondary link composed of a transmitter equipped with multiple antennas and a single-antenna receiver sharing the same spectrum with a set of primary links composed of a single-antenna transmitter and a single-antenna receiver. The proposed schemes jointly select a beam, among a set of power-optimized random beams, as well as the primary spectrum that maximizes the signal-to-interference-plus-noise ratio (SINR) of the secondary link while satisfying the primary interference constraint. In particular, we consider the case where the interference level is described by a q-bit description of its magnitude, whereby we propose a technique to find the optimal quantizer thresholds in a mean square error (MSE) sense. © 2013 IEEE.

  5. Microsecond molecular dynamics simulations of the open state structure of a bacterial voltage-gated sodium channel reveal mechanisms of ion selectivity and conduction

    OpenAIRE

    Ulmschneider, Martin B.; Bagneris, Claire; McCusker, Emily C.; Ulmschneider, J.P.; Wallace, Bonnie A.

    2013-01-01

    Microsecond atomic detail equilibrium molecular dynamics simulations based on the open-state crystal structure (McCusker et al, 2012, Nature Comm) of a bacterial voltage-gated sodium channel (NavMs) have been employed to characterize the mechanisms underlying ion selectivity and conductance of the channel embedded in a lipid bilayer membrane. This approach captured the full plethora of conduction events, revealing a complex mixture of single and multi-ion phenomena, with decoupled rapid bi-di...

  6. Multi-agent Q-Learning of Channel Selection in Multi-user Cognitive Radio Systems: A Two by Two Case

    OpenAIRE

    Li, Husheng

    2009-01-01

    Resource allocation is an important issue in cognitive radio systems. It can be done by carrying out negotiation among secondary users. However, significant overhead may be incurred by the negotiation since the negotiation needs to be done frequently due to the rapid change of primary users' activity. In this paper, a channel selection scheme without negotiation is considered for multi-user and multi-channel cognitive radio systems. To avoid collision incurred by non-coordination, each user s...

  7. The Scorpion Toxin Analogue BmKTX-D33H as a Potential Kv1.3 Channel-Selective Immunomodulator for Autoimmune Diseases

    Science.gov (United States)

    Ye, Fang; Hu, Youtian; Yu, Weiwei; Xie, Zili; Hu, Jun; Cao, Zhijian; Li, Wenxin; Wu, Yingliang

    2016-01-01

    The Kv1.3 channel-acting scorpion toxins usually adopt the conserved anti-parallel β-sheet domain as the binding interface, but it remains challenging to discover some highly selective Kv1.3 channel-acting toxins. In this work, we investigated the pharmacological profile of the Kv1.3 channel-acting BmKTX-D33H, a structural analogue of the BmKTX scorpion toxin. Interestingly, BmKTX-D33H, with its conserved anti-parallel β-sheet domain as a Kv1.3 channel-interacting interface, exhibited more than 1000-fold selectivity towards the Kv1.3 channel as compared to other K+ channels (including Kv1.1, Kv1.2, Kv1.7, Kv11.1, KCa2.2, KCa2.3, and KCa3.1). As expected, BmKTX-D33H was found to inhibit the cytokine production and proliferation of both Jurkat cells and human T cells in vitro. It also significantly improved the delayed-type hypersensitivity (DTH) responses, an autoreactive T cell-mediated inflammation in rats. Amino acid sequence alignment and structural analysis strongly suggest that the “evolutionary” Gly11 residue of BmKTX-D33H interacts with the turret domain of Kv1 channels; it appears to be a pivotal amino acid residue with regard to the selectivity of BmKTX-D33H towards the Kv1.3 channel (in comparison with the highly homologous scorpion toxins). Together, our data indicate that BmKTX-D33H is a Kv1.3 channel–specific blocker. Finally, the remarkable selectivity of BmKTX-D33H highlights the great potential of evolutionary-guided peptide drug design in future studies. PMID:27104568

  8. Hybrid genetic algorithm approach for selective harmonic control

    Energy Technology Data Exchange (ETDEWEB)

    Dahidah, Mohamed S.A. [Faculty of Engineering, Multimedia University, 63100, Jalan Multimedia-Cyberjaya, Selangor (Malaysia); Agelidis, Vassilios G. [School of Electrical and Information Engineering, The University of Sydney, NSW (Australia); Rao, Machavaram V. [Faculty of Engineering and Technology, Multimedia University, 75450, Jalan Ayer Keroh Lama-Melaka (Malaysia)

    2008-02-15

    The paper presents an optimal solution for a selective harmonic elimination pulse width modulated (SHE-PWM) technique suitable for a high power inverter used in constant frequency utility applications. The main challenge of solving the associated non-linear equations, which are transcendental in nature and, therefore, have multiple solutions, is the convergence, and therefore, an initial point selected considerably close to the exact solution is required. The paper discusses an efficient hybrid real coded genetic algorithm (HRCGA) that reduces significantly the computational burden, resulting in fast convergence. An objective function describing a measure of the effectiveness of eliminating selected orders of harmonics while controlling the fundamental, namely a weighted total harmonic distortion (WTHD) is derived, and a comparison of different operating points is reported. It is observed that the method was able to find the optimal solution for a modulation index that is higher than unity. The theoretical considerations reported in this paper are verified through simulation and experimentally on a low power laboratory prototype. (author)

  9. Hybrid genetic algorithm approach for selective harmonic control

    International Nuclear Information System (INIS)

    The paper presents an optimal solution for a selective harmonic elimination pulse width modulated (SHE-PWM) technique suitable for a high power inverter used in constant frequency utility applications. The main challenge of solving the associated non-linear equations, which are transcendental in nature and, therefore, have multiple solutions, is the convergence, and therefore, an initial point selected considerably close to the exact solution is required. The paper discusses an efficient hybrid real coded genetic algorithm (HRCGA) that reduces significantly the computational burden, resulting in fast convergence. An objective function describing a measure of the effectiveness of eliminating selected orders of harmonics while controlling the fundamental, namely a weighted total harmonic distortion (WTHD) is derived, and a comparison of different operating points is reported. It is observed that the method was able to find the optimal solution for a modulation index that is higher than unity. The theoretical considerations reported in this paper are verified through simulation and experimentally on a low power laboratory prototype

  10. Efficacy of oxytetracycline hydrochloride bath immersion to control external columnaris disease on walleye and channel catfish fingerlings

    Science.gov (United States)

    Rach, J.J.; Johnson, Aaron H.; Rudacille, J.B.; Schleis, S.M.

    2008-01-01

    The efficacy of oxytetracycline hydrochloride (OTC-HCl) in controlling external columnaris disease caused by Flavobacterium columnare on fingerling walleyes Sander vitreus and channel catfish Ictalurus punctatus was evaluated in two on-site hatchery trials. Microscopic examination of skin scrapings before treatment confirmed the presence of bacteria with characteristics indicative of F. columnare.in separate trials, walleyes (4.4 g) and channel catfish (1.5 g) were exposed to 60-min static bath treatments of OTC-HCl at 0, 10, and 20 mg/L (walleyes) or 0, 10, 20, and 40 mg/L (channel catfish) on three consecutive days. Each treatment regimen was tested in triplicate, and each replicate contained either 30 walleyes or 55 channel catfish. Posttreatment presumptive disease diagnosis indicated that F. columnare was the disease agent causing the mortality in both species of fish. Walleye survival at 10 d posttreatment was greater in the 10- and 20-mg/L treatment groups than in the control group; however, only the 10-mg/L treatment significantly (P < 0.05) increased walleye survival in comparison with controls. In the channel catfish trial, survival at 10 d posttreatment was significantly (P < 0.05) greater for all OTC-HCl treatment groups relative to controls. Results from these trials indicated that OTC-HCl treatments effectively reduced mortality in walleyes (10 mg/L only) and channel catfish infected with F. columnare. ?? Copyright by the American Fisheries Society 2008.

  11. Production control and supplier selection under demand disruptions

    Directory of Open Access Journals (Sweden)

    Xianzhe Chen

    2010-12-01

    Full Text Available This paper investigates the effects of demand disruptions on production control and supplier selection in a three-echelon supply chain system. The customer demand is modeled as a jump-diffusion process in a continuous-time setting. A two-number production-inventory policy is implemented in the production control model for the manufacturer. The objective is to minimize the long-term average total cost consisting of backlog cost, holding cost, switching cost, and ordering cost. The simulated annealing method is applied to search the optimal critical switching values. Furthermore, an improved analytical hierarchy process (AHP is proposed to select the best supplier, based on quantitative factors such as the optimal long-term total cost obtained through the simulated annealing method under demand disruptions and qualitative factors such as quality and service. Numerical studies are conducted to demonstrate the effects of demand disruptions in the face of various risk scenarios. Managerial insights from simulation results are provided as well. Our approaches can be implemented as the “stress test” for companies in front of various supply chain disruption scenarios.

  12. Passivity-Based Output-Feedback Control of Turbulent Channel Flow

    CERN Document Server

    Heins, Peter H; Sharma, Ati S

    2016-01-01

    This paper describes a robust linear time-invariant output-feedback control strategy to reduce turbulent fluctuations, and therefore skin-friction drag, in wall-bounded turbulent fluid flows, that nonetheless gives performance guarantees in the nonlinear turbulent regime. The novel strategy is effective in reducing the supply of available energy to feed the turbulent fluctuations, expressed as reducing a bound on the supply rate to a quadratic storage function. The nonlinearity present in the equations that govern the dynamics of the flow is known to be passive and can be considered as a feedback forcing to the linearised dynamics (a Lur'e decomposition). Therefore, one is only required to control the linear dynamics in order to make the system close to passive. The ten most energy-producing spatial modes of a turbulent channel flow were identified. Passivity-based controllers were then generated to control these modes. The controllers require measurements of streamwise and spanwise wall-shear stress, and the...

  13. Improving catalytic selectivity through control of adsorption orientation

    Science.gov (United States)

    Pang, Simon H.

    monolayer formed by 1,2-benzenedithiol, we determined that hydrodeoxygenation selectively occurred on catalyst particle steps and edges from an upright structure, whereas decarbonylation occurred on particle terraces from a flat-lying structure. Control of furfural adsorption orientation was also achieved through the use of NiCu bimetallic catalysts. The aromatic furan ring was repelled from surface Cu, leading to an upright structure. However, under hydrogenation conditions, Ni tended to be near the surface of thin films and catalysts, leading to less dramatic selectivity enhancement. The presence of a 1-octadecanethiol monolayer kinetically stabilized the surface termination, allowing Cu to remain at the surface.

  14. Theory and application of electron channelling contrast imaging under controlled diffraction conditions

    International Nuclear Information System (INIS)

    Electron channelling contrast imaging (ECCI) is a powerful technique for observing crystal defects, such as dislocations, stacking faults, twins and grain boundaries in the scanning electron microscope. Electron channelling contrast (ECC) is strongest when the primary electron beam excites so called two-beam diffraction conditions in the crystal. In the present approach this is achieved, by a combination of crystal orientation measurement using electron backscatter diffraction (EBSD) and simulation of electron channelling patterns. From the latter, the crystal is rotated such that two-beam diffraction conditions are achieved. This technique is called “ECCI under controlled diffraction conditions” or cECCI. Following an extensive literature review, this paper presents a simple, yet instructive and demonstrative treatment of the theory of ECC of lattice defects based on Bloch wave theory using a two-beam approach. This is followed by a discussion of technical issues associated with an ideal ECC set-up such as optimum detector position and microscope conditions. Subsequently, the appearance of different types of lattice defects under ECCI conditions; namely of dislocations, stacking faults, slip lines, and nanotwins, is discussed in detail. It is shown how different types of defects are distinguished and which type of crystallographic information can be extracted from such observations. Finally, the limits of the technique, particularly in terms of spatial resolution and depth of visibility are discussed and a comparison with the EBSD and transmission electron microscopy techniques with respect to imaging lattice defects is provided. In contrast to many investigations recently published in the literature, the current paper focuses on ‘true’ backscattering, i.e. on a signal that is recorded with a conventional backscatter detector positioned below the pole piece, and not on forward scattering, where the signal is recorded on a detector usually positioned below

  15. Integrated design optimization of voltage channel distribution and control voltages for tracking the dynamic shapes of smart plates

    International Nuclear Information System (INIS)

    This paper investigates a control scheme for tracking the dynamic shapes of structures with limited numbers of voltage channels. Integrated design optimization of voltage channel distribution and control parameters for structural dynamic shape control is formulated as an optimization problem with discrete variables and continuous variables coexisting. A two-level optimization method based on a simulated annealing algorithm is proposed. In the first level, the optimum channel distribution is determined by optimizing the objective function which is the optimal value obtained in the second level. The optimum control parameters are obtained by using a sequential linear least-squares algorithm in the second level. The effectiveness of the present design methodology and optimization scheme is then demonstrated through numerical examples for tracking the dynamic shapes of composite plates

  16. Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids.

    Science.gov (United States)

    Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria; Heyman, Sarah; Stary-Weinzinger, Anna; Yuan, Peng; Nichols, Colin G

    2016-09-01

    Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL(-)) with a distinct second site is required for high PIP2 sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2 sensitivity, even in the absence of PL(-) Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP2 (2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domain (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL(-) binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP2 site and explaining the positive allostery between PL(-) binding and PIP2 sensitivity. PMID:27527100

  17. Isolation, synthesis and characterization of ω-TRTX-Cc1a, a novel tarantula venom peptide that selectively targets L-type Cav channels.

    Science.gov (United States)

    Klint, Julie K; Berecki, Géza; Durek, Thomas; Mobli, Mehdi; Knapp, Oliver; King, Glenn F; Adams, David J; Alewood, Paul F; Rash, Lachlan D

    2014-05-15

    Spider venoms are replete with peptidic ion channel modulators, often with novel subtype selectivity, making them a rich source of pharmacological tools and drug leads. In a search for subtype-selective blockers of voltage-gated calcium (CaV) channels, we isolated and characterized a novel 39-residue peptide, ω-TRTX-Cc1a (Cc1a), from the venom of the tarantula Citharischius crawshayi (now Pelinobius muticus). Cc1a is 67% identical to the spider toxin ω-TRTX-Hg1a, an inhibitor of CaV2.3 channels. We assembled Cc1a using a combination of Boc solid-phase peptide synthesis and native chemical ligation. Oxidative folding yielded two stable, slowly interconverting isomers. Cc1a preferentially inhibited Ba(2+) currents (IBa) mediated by L-type (CaV1.2 and CaV1.3) CaV channels heterologously expressed in Xenopus oocytes, with half-maximal inhibitory concentration (IC50) values of 825nM and 2.24μM, respectively. In rat dorsal root ganglion neurons, Cc1a inhibited IBa mediated by high voltage-activated CaV channels but did not affect low voltage-activated T-type CaV channels. Cc1a exhibited weak activity at NaV1.5 and NaV1.7 voltage-gated sodium (NaV) channels stably expressed in mammalian HEK or CHO cells, respectively. Experiments with modified Cc1a peptides, truncated at the N-terminus (ΔG1-E5) or C-terminus (ΔW35-V39), demonstrated that the N- and C-termini are important for voltage-gated ion channel modulation. We conclude that Cc1a represents a novel pharmacological tool for probing the structure and function of L-type CaV channels. PMID:24561180

  18. Analytical Results to Improve the Capacity of A Cellular System In Frequency Selective Rayleigh Fading Channel

    Directory of Open Access Journals (Sweden)

    Pravindra Kumar

    2010-10-01

    Full Text Available One of the biggest draw back of wireless environment is the limited bandwidth. However, the users sharing this limited bandwidth have been increased considerably by using SDMA technique that can enhancethe capacity of communication system. There are some techniques that can increase the capacity of the cellular system, these are- Spreading Technique, Error Control Coding Technique, Multipath Diversity Technique ( i.e. Rake Receiver, Smart Antenna Technique. In this paper we have used all these technique and examined how thecapacity of cellular system vary with varying the different parameters such as- the value of spreading factor, the number of Rake fingers, the number of interfering cells, value of directivity of Adaptive Antenna at base station. In the results we find that the capacity of a cellular system is varying with these parameters.

  19. Multi-channel spark gaps with lamellar control electrodes, their development and application

    International Nuclear Information System (INIS)

    The reviews multichannel (several tens) low-induced (∼ 1 nH) gas-filled gaps (MGL) with lamellar control electrodes rated at ≤ 100 kV operating voltage and up to 100 kA switching current. Switches are designed to obtain nanosecond accuracy of operation delay as to initiating pulse when electrical power safety margin is equal to 100% dictated by pressure (> 0.1 MPa) of a filling gas. One examined electric circuits of initiation of discharge acceleration in MGL, studied transient processes in the mentioned circuits and factors affecting parameters of processes, on delay and rate of break-tougher of gaps. One described the available designs of MGLs, multicable systems of parallel starting of a large number of MGLs and application of 48 four-channel MGLs rated at 50 kV. The mentioned spark gaps are applied in new power linear accelerators of electrons

  20. Efficient multicast data transfer with congestion control using dynamic source channels

    CERN Document Server

    Lucas, Vincent; Grad, Dominique; Hilt, Benoît

    2010-01-01

    The most efficient receiver-driven multicast congestion control protocols use dynamic channels. This means that each group has a cyclic rate variation with a continuously decreasing phase. Despite promising results in terms of fairness, using efficiently these dynamic groups could be a challenging task for application programmers. This paper presents a sequencer which maps out application data to dynamic groups in an optimal way. Multiple applications such as file transfer or video streaming, can use this sequencer, thanks to a simple API usable with any buffer containing the most important data first. To evaluate this solution, we designed a file transfer software using a FEC encoding. Results show the sequencer optimal behavior and the file transfer efficiency, as a single download generates only little more overhead than TCP . Moreover, download time is almost independent of the number of receivers, and is already faster than TCP with 2 competing downloads.

  1. Separation of Parkinson's patients in early and mature stages from control subjects using one EOG channel

    DEFF Research Database (Denmark)

    Christensen, Julie A.E.; Frandsen, Rune; Kempfner, Jacob; Arvastson, Lars; Christensen, Soren R.; Jennum, Poul; Sorensen, Helge B.D.

    2012-01-01

    subjects was done by a leave-one-out validation approach using same method, and reached a sensitivity of 95%, a specificity of 70% and an accuracy of 86.7%. It was found that in the optimal subset of features, two hold lower frequencies reflecting the rapid eye movements and two hold higher frequencies...... reflecting EMG activity. This study demonstrates that both analysis of eye movements during sleep as well as EMG activity measured at the EOG channel hold potential of being biomarkers for Parkinson's disease.......In this study, polysomnographic left side EOG signals from ten control subjects, ten iRBD patients and ten Parkinson's patients were decomposed in time and frequency using wavelet transformation. A total of 28 features were computed as the means and standard deviations in energy measures from...

  2. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    OpenAIRE

    Xiang Wan; Ben Geng Cai; Yun Bo Li; Tie Jun Cui

    2015-01-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the met...

  3. Gating schemes for controlling the electron wavefunction between GaAs and In0.05Ga0.95As quasi-one-dimensional channels

    International Nuclear Information System (INIS)

    The selective composition control of the electron wavefunction in a GaAs/InGaAs double quantum well device is presented for two different gating schemes. In particular, electron-beam defined surface gates schemes allow the definition of non-ballistic quasi-one-dimensional conduction channels in each of the quantum wells and result in the ability to electrostatically move the electron wavefunction between the two materials. The use of such a device as the basis for a spin qubit, due to the differing g-factors, and the investigation of other spin-related phenomena in one-dimension are discussed. (letter to the editor)

  4. Photodissociation of the carbon monoxide dication in the {sup 3}Σ{sup −} manifold: Quantum control simulation towards the C{sup 2+} + O channel

    Energy Technology Data Exchange (ETDEWEB)

    Vranckx, S. [Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB), CP 160/09, B-1050 Brussels (Belgium); Laboratoire de Chimie Physique (UMR 8000), Université Paris-Sud, Orsay 91405 (France); Loreau, J.; Vaeck, N. [Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB), CP 160/09, B-1050 Brussels (Belgium); Meier, C. [Laboratoire Collisions Agrégats Réactivité, UMR 5589, IRSAMC, Université Toulouse III Paul Sabatier, Bât. 3R1b4, Toulouse (France); Desouter-Lecomte, M., E-mail: michele.desouter-lecomte@u-psud.fr [Laboratoire de Chimie Physique (UMR 8000), Univ. Paris Sud, Université Paris-Saclay, Orsay 91405 (France); Département de Chimie, B6c Université de Liège, Sart Tilman, 4000 Liège (Belgium)

    2015-10-28

    The photodissociation and laser assisted dissociation of the carbon monoxide dication X{sup 3}Π CO{sup 2+} into the {sup 3}Σ{sup −} states are investigated. Ab initio electronic structure calculations of the adiabatic potential energy curves, radial nonadiabatic couplings, and dipole moments for the X {sup 3}Π state are performed for 13 excited {sup 3}Σ{sup −} states of CO{sup 2+}. The photodissociation cross section, calculated by time-dependent methods, shows that the C{sup +} + O{sup +} channels dominate the process in the studied energy range. The carbon monoxide dication CO{sup 2+} is an interesting candidate for control because it can be produced in a single, long lived, v = 0 vibrational state due to the instability of all the other excited vibrational states of the ground {sup 3}Π electronic state. In a spectral range of about 25 eV, perpendicular transition dipoles couple this {sup 3}Π state to a manifold of {sup 3}Σ{sup −} excited states leading to numerous C{sup +} + O{sup +} channels and a single C{sup 2+} + O channel. This unique channel is used as target for control calculations using local control theory. We illustrate the efficiency of this method in order to find a tailored electric field driving the photodissociation in a manifold of strongly interacting electronic states. The selected local pulses are then concatenated in a sequence inspired by the “laser distillation” strategy. Finally, the local pulse is compared with optimal control theory.

  5. [3H]TA-3090, a selective benzothiazepine-type calcium channel receptor antagonist: In vitro characterization

    International Nuclear Information System (INIS)

    Binding of the new benzothiazepine calcium channel blocker, (+)-(2S,3S)-3-acetoxy-8-chloro-5-(2-(dimethylamino)ethyl)-2,3-dihydro-2- (4- methoxyphenyl)-1,5-benzothiazepine-4-(5H)-one maleate, [3H]TA-3090, was characterized and its specificity for rat myocardial benzothiazepine receptors described. Scatchard plots and nonlinear regression analysis of specific [3H]TA-3090 binding best fit a one-site binding model (Kd = 8.8 +/- 2.7 nM, Bmax = 132 +/- 38 fmol/mg protein). Kinetically derived affinity constants were in close agreement (Kd = 7.86 nM) with those obtained from analysis of equilibrium binding data. In comparison, under identical conditions [3H]diltiazem exhibited a Kd of 38 nM and Bmax, 106 fmol/mg protein. Specific binding was saturable, reversible and stereoselective (d-cis-TA-3090 Ki = 14 nM; 1-cis-TA-3090 Ki = 2700 nM). Competitions for [3H]TA-3090 binding were conducted with nifedipine, propranolol, prazosin, quinuclidinyl benzilate, verapamil and yohimbine. Only the calcium channel blockers nifedipine and verapamil inhibited specific [3H]TA-3090 binding. Nifedipine could maximally inhibit only 52% of specifically bound [3H]TA-3090 at 10 microM. In contrast, however, 10 microM verapamil completely inhibited specific radioligand binding (Ki = 93 +/- 28 nM) but with six times less efficacy than TA-3090. Thus, these data demonstrate that [3H]TA-3090 is a potent radioligand selective for the benzothiazepine binding site and is consistent with the hypothesis that [3H]TA-3090 interacts with a myocardial benzothiazepine receptor site

  6. Subtype-selective activation of K(v)7 channels by AaTXKβ₂₋₆₄, a novel toxin variant from the Androctonus australis scorpion venom.

    Science.gov (United States)

    Landoulsi, Zied; Miceli, Francesco; Palmese, Angelo; Amoresano, Angela; Marino, Gennaro; El Ayeb, Mohamed; Taglialatela, Maurizio; Benkhalifa, Rym

    2013-11-01

    K(v)7.4 channel subunits are expressed in central auditory pathways and in inner ear sensory hair cells and skeletal and smooth muscle cells. Openers of K(v)7.4 channels have been suggested to improve hearing loss, systemic or pulmonary arterial hypertension, urinary incontinence, gastrointestinal and neuropsychiatric diseases, and skeletal muscle disorders. Scorpion venoms are a large source of peptides active on K⁺ channels. Therefore, we have optimized a combined purification/screening procedure to identify specific modulator(s) of K(v)7.4 channels from the venom of the North African scorpion Androctonus australis (Aa). We report the isolation and functional characterization of AaTXKβ₂₋₆₄, a novel variant of AaTXKβ₁₋₆₄, in a high-performance liquid chromatography fraction from Aa venom (named P8), which acts as the first peptide activator of K(v)7.4 channels. In particular, in both Xenopus oocytes and mammalian Chinese hamster ovary cells, AaTXKβ₂₋₆₄, but not AaTXKβ₁₋₆₄, hyperpolarized the threshold voltage of current activation and increased the maximal currents of heterologously expressed K(v)7.4 channels. AaTXKβ₂₋₆₄ also activated K(v)7.3, K(v)7.2/3, and K(v)7.5/3 channels, whereas homomeric K(v)1.1, K(v)7.1, and K(v)7.2 channels were unaffected. We anticipate that these results may prove useful in unraveling the novel biologic roles of AaTXKβ₂₋₆₄-sensitive K(v)7 channels and developing novel pharmacologic tools that allow subtype-selective targeting of K(v)7 channels. PMID:24019223

  7. Acoustic bubble: Controlled and selective micropropulsion and chemical waveform generator

    Science.gov (United States)

    Ahmed, Daniel

    The physics governing swimming at the microscale---where viscous forces dominate over inertial---is distinctly different than that at the macroscale. Devices capable of finely controlled swimming at the microscale could enable bold ideas such as targeted drug delivery, non-invasive microsurgery, and precise materials assembly. Progress has already been made towards such artificial microswimmers using several means of actuation: chemical reactions and applied magnetic, electric or acoustic fields. However, the prevailing goal of selective actuation of a single microswimmer from within a group, the first step towards collaborative, guided action by a group of swimmers, has so far not been achieved. Here I present a new class of microswimmer that accomplishes for the first time selective actuation (Chapter 1). The swimmer design eschews the commonly-held design paradigm that microswimmers must use non-reciprocal motion to achieve propulsion; instead, the swimmer is propelled by oscillatory motion of an air bubble trapped within the swimmer's polymer body. This oscillatory motion is driven by a low-power biocompatible acoustic field to the ambient liquid, with meaningful swimmer propulsion occurring only at resonance frequencies of the bubble. This acoustically-powered microswimmer performs controllable rapid translational and rotational motion even in highly viscous liquid. By using a group of swimmers each with a different bubble size (and thus different resonance frequencies) selective actuation of a single swimmer from among the group can be readily achieved. Cellular response to chemical microenvironments depends on the spatiotemporal characteristics of the stimulus, which is central to many biological processes including gene expression, cell migration, differentiation, apoptosis, and intercellular signaling. To date, studies have been limited to digital (or step) chemical stimulation with little control over the temporal counterparts. Microfluidic approaches

  8. Selecting a Control Strategy for Plug and Process Loads

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, C.; Sheppy, M.; Brackney, L.; Pless, S.; Torcellini, P.

    2012-09-01

    Plug and Process Loads (PPLs) are building loads that are not related to general lighting, heating, ventilation, cooling, and water heating, and typically do not provide comfort to the building occupants. PPLs in commercial buildings account for almost 5% of U.S. primary energy consumption. On an individual building level, they account for approximately 25% of the total electrical load in a minimally code-compliant commercial building, and can exceed 50% in an ultra-high efficiency building such as the National Renewable Energy Laboratory's (NREL) Research Support Facility (RSF) (Lobato et al. 2010). Minimizing these loads is a primary challenge in the design and operation of an energy-efficient building. A complex array of technologies that measure and manage PPLs has emerged in the marketplace. Some fall short of manufacturer performance claims, however. NREL has been actively engaged in developing an evaluation and selection process for PPLs control, and is using this process to evaluate a range of technologies for active PPLs management that will cap RSF plug loads. Using a control strategy to match plug load use to users' required job functions is a huge untapped potential for energy savings.

  9. A user-friendly wearable single-channel EOG-based human-computer interface for cursor control

    OpenAIRE

    ANG, AMS; Zhang, Z.; Hung, YS; Mak, JNF

    2015-01-01

    This paper presents a novel wearable single-channel electrooculography (EOG) based human-computer interface (HCI) with a simple system design and robust performance. In the proposed system, EOG signals for control are generated from double eye blinks, collected by a commercial wearable device (the NeuroSky MindWave headset), and then converted into a sequence of commands that can control cursor navigations and actions. The EOG-based cursor control system was tested on 8 subjects in indoor or ...

  10. Inhibition of cell proliferation by a selective inhibitor of the Ca2+-activated Cl− channel, Ano1

    International Nuclear Information System (INIS)

    Highlights: ► T16Ainh-A01 blocked Ano1 currents in HEK cells expressing Ano1. ► T16Ainh-A01 reduced proliferation in ICC primary cultures and CFPAC-1 cell line. ► T16Ainh-A01 reduced proliferation of ICC in intact smooth muscle strips. -- Abstract: Background: Ion channels play important roles in regulation of cellular proliferation. Ano1 (TMEM16A) is a Ca2+-activated Cl− channel expressed in several tumors and cell types. In the muscle layers of the gastrointestinal tract Ano1 is selectively expressed in interstitial cells of Cajal (ICC) and appears to be required for normal gastrointestinal slow wave electrical activity. However, Ano1 is expressed in all classes of ICC, including those that do not generate slow waves suggesting that Ano1 may have other functions. Indeed, a role for Ano1 in regulating proliferation of tumors and ICC has been recently suggested. Recently, a high-throughput screen identified a small molecule, T16Ainh-A01 as a specific inhibitor of Ano1. Aim: To investigate the effect of the T16Ainh-A01 inhibitor on proliferation in ICC and in the Ano1-expressing human pancreatic cancer cell line CFPAC-1. Methods: Inhibition of Ano1 was demonstrated by whole cell voltage clamp recordings of currents in cells transfected with full-length human Ano1. The effect of T16Ainh-A01 on ICC proliferation was examined in situ in organotypic cultures of intact mouse small intestinal smooth muscle strips and in primary cell cultures prepared from these tissues. ICC were identified by Kit immunoreactivity. Proliferating ICC and CFPAC-1 cells were identified by immunoreactivity for the nuclear antigen Ki67 or EdU incorporation, respectively. Results: T16Ainh-A01 inhibited Ca2+-activated Cl− currents by 60% at 10 μM in a voltage-independent fashion. Proliferation of ICC was significantly reduced in primary cultures from BALB/c mice following treatment with T16Ainh-A01. Proliferation of the CFPAC-1 human cell-line was also reduced by T16Ainh-A01. In

  11. Bearer channel control protocol for the dynamic VB5.2 interface in ATM access networks

    Science.gov (United States)

    Fragoulopoulos, Stratos K.; Mavrommatis, K. I.; Venieris, Iakovos S.

    1996-12-01

    In the multi-vendor systems, a customer connected to an Access network (AN) must be capable of selecting a specific Service Node (SN) according to the services the SN provides. The multiplicity of technologically varying AN calls for the definition of a standard reference point between the AN and the SN widely known as the VB interface. Two versions are currently offered. The VB5.1 is simpler to implement but is not as flexible as the VB5.2, which supports switched connections. The VB5.2 functionality is closely coupled to the Broadband Bearer Channel Connection Protocol (B-BCCP). The B-BCCP is used for conveying the necessary information for dynamic resource allocation, traffic policing and routing in the AN as well as for information exchange concerning the status of the AN before a new call is established by the SN. By relying on such a protocol for the exchange of information instead of intercepting and interpreting signalling messages in the AN, the architecture of the AN is simplified because the functionality related to processing is not duplicated. In this paper a prominent B- BCCP candidate is defined, called the Service node Access network Interaction Protocol.

  12. The demonstration of the Si nano-tube device with the promising short channel control

    Science.gov (United States)

    Liao, M.-H.; Chen, P.-G.

    2015-10-01

    In addition to the development of the nano-wire device, the vertical gate-all-around (V-GAA) Si nano-tube (NT) device structure is proposed with the promising device performance in this work. The vertical device structure makes the transistor easy to be scaled down continuously to meet the complementary metal-oxide-semiconductor scaling needs of the 10/7 nm technology node and beyond. The NT device with the center hollow structure has the capability to deplete the out-of gate control carriers in the center of the nano-wire device and further results in the better device short channel control. Based on the simulation data, the V-GAA Si NT device can keep the Ion-state current the same and reduce the Ioff-state stand-by power. With the demonstration of the promising device performance, the proposed V-GAA Si NT device can be regarded as one of the most promising candidates for the future application of the sub-10/7 nm logic device.

  13. Dynamic Routing Algorithm Based on the Channel Quality Control for Farmland Sensor Networks

    Directory of Open Access Journals (Sweden)

    Dongfeng Xu

    2014-04-01

    Full Text Available This article reports a Dynamic Routing Algorithm for Farmland Sensor Networks (DRA-FSN based on channel quality control to improve energy efficiency, which combines the distance and communication characteristics of farmland wireless sensor network. The functional architecture of the DRA-FSN algorithm, routing establish the mechanisms, the communication transmission mechanism, the global routing beacon return mechanism, abnormal node handling mechanism and sensor networks timing control mechanisms were designed in detail in this article. This article also evaluates and simulated the performance of DRA-FSN algorithm in different conditions from energy efficiency, packet energy consumption and packet distribution balance by comparing DRA-FSN algorithm with DSDV, EAP algorithm. Simulations showed that the DRA-FSN was more energy efficient than EAP and DSDV, the DRA-FSN algorithm overcame the shortcoming that capacity and bandwidth of the routing table correspondingly increase as more and more nodes joining the network. It has better performance in scalability and network loading balance

  14. ANALYSIS OF A CUMULANT-BASED 2D-RAKE RECEIVER FOR CDMA SYSTEM OVER FREQUENCY-SELECTIVE FADING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    杨维; 程时昕

    2003-01-01

    The conventional 2D-Rake receivers for code-division multiple access (CDMA) system over frequency-selective fading channels are generally based on the second-order statistics while assuming perfect array conditions. However, the sensor response, location uncertainty, and the use of sample statistics can severely degrade the performance of second-order statistics processing. And in practical application, it is impossible to calibrate the array frequently. In this paper a cumulant-based 2D-Rake receiver for synchronous CDMA system with decorrelator is presented. Decorrelating is a multi-user detection approach that not only provides a fundamental solution to the mutual interference problem in CDMA communications but also makes it convenient for the decoupled signal to be processed spatially and temporally. High-order signal processing has some inherent advantages over that of second-order. Employing second-order statistics it is impossible to estimate source steering vector blindly, while employing higher than second-order cumulants, this purpose can be achieved. The performance analysis shows that employing cumulant-based signal processing technique the proposed 2D-Rake receiver is blind and demonstrates excellent performance.

  15. Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection

    KAUST Repository

    Xia, Minghua

    2012-11-01

    For cooperative amplify-and-forward (AF) relaying in spectrum-sharing wireless systems, secondary users share spectrum resources originally licensed to primary users to communicate with each other and, thus, the transmit power of secondary transmitters is strictly limited by the tolerable interference powers at primary receivers. Furthermore, the received signals at a relay and at a secondary receiver are inevitably interfered by the signals from primary transmitters. These co-channel interferences (CCIs) from concurrent primary transmission can significantly degrade the performance of secondary transmission. This paper studies the effect of CCIs on outage probability of the secondary link in a spectrum-sharing environment. In particular, in order to compensate the performance loss due to CCIs, the transmit powers of a secondary transmitter and its relaying node are respectively optimized with respect to both the tolerable interference powers at the primary receivers and the CCIs from the primary transmitters. Moreover, when multiple relays are available, the technique of opportunistic relay selection is exploited to further improve system performance with low implementation complexity. By analyzing lower and upper bounds on the outage probability of the secondary system, this study reveals that it is the tolerable interference powers at primary receivers that dominate the system performance, rather than the CCIs from primary transmitters. System designers will benefit from this result in planning and designing next-generation broadband spectrum-sharing systems.

  16. Networking remote control of nuclear instruments based on multi-channel serial communication in ARM-linux

    International Nuclear Information System (INIS)

    Measurement and control of nuclear instruments in particular environment is not suitable for on-site direct operation. In addition, monitor of nuclear instruments should be multi-point binding and continuous monitoring. With those characteristics, the solution for remote control and nuclear instruments networking by multi-channel serial communication interface under ARM-Linux is proposed. On the basis of practical application, mode of hardware connection for multi-channel serial interface is analyzed. Moreover, the paper also describes in detail serial port initialization and multi-port serial programming. Finally experiments prove that multi-channel serial communication can improve data transmission rate of nuclear instruments, but also achieve remote monitor and centralized management of nuclear instruments networking. (authors)

  17. Transmission Control of Two-User Slotted ALOHA Over Gilbert-Elliott Channel: Stability and Delay Analysis

    CERN Document Server

    Fanous, Anthony

    2011-01-01

    In this paper, we consider the problem of calculating the stability region and average delay of two user slotted ALOHA over a Gilbert-Elliott channel, where users have channel state information and adapt their transmission probabilities according to the channel state. Each channel has two states, namely, the 'good' and 'bad' states. In the 'bad' state, the channel is assumed to be in deep fade and the transmission fails with probability one, while in the 'good' state, there is some positive success probability. We calculate the Stability region with and without Multipacket Reception capability as well as the average delay without MPR. Our results show that the stability region of the controlled S-ALOHA is always a superset of the stability region of uncontrolled S-ALOHA. Moreover, if the channel tends to be in the 'bad' state for long proportion of time, then the stability region is a convex Polyhedron strictly containing the TDMA stability region and the optimal transmission strategy is to transmit with prob...

  18. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate

    OpenAIRE

    Ivanov, Vadim; Ivanova, Svetlana; KALINOVSKY, TATIANA; NIEDZWIECKI, ALEKSANDRA; RATH, MATTHIAS

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition...

  19. On stochastic geometry modeling of cellular uplink transmission with truncated channel inversion power control

    KAUST Repository

    Elsawy, Hesham

    2014-08-01

    Using stochastic geometry, we develop a tractable uplink modeling paradigm for outage probability and spectral efficiency in both single and multi-tier cellular wireless networks. The analysis accounts for per user equipment (UE) power control as well as the maximum power limitations for UEs. More specifically, for interference mitigation and robust uplink communication, each UE is required to control its transmit power such that the average received signal power at its serving base station (BS) is equal to a certain threshold ρo. Due to the limited transmit power, the UEs employ a truncated channel inversion power control policy with a cutoff threshold of ρo. We show that there exists a transfer point in the uplink system performance that depends on the following tuple: BS intensity λ, maximum transmit power of UEs Pu, and ρo. That is, when Pu is a tight operational constraint with respect to (w.r.t.) λ and ρo, the uplink outage probability and spectral efficiency highly depend on the values of λ and ρo. In this case, there exists an optimal cutoff threshold ρ*o, which depends on the system parameters, that minimizes the outage probability. On the other hand, when Pu is not a binding operational constraint w.r.t. λ and ρo, the uplink outage probability and spectral efficiency become independent of λ and ρo. We obtain approximate yet accurate simple expressions for outage probability and spectral efficiency, which reduce to closed forms in some special cases. © 2002-2012 IEEE.

  20. Fragile X mental retardation protein controls synaptic vesicle exocytosis by modulating N-type calcium channel density

    Science.gov (United States)

    Ferron, Laurent; Nieto-Rostro, Manuela; Cassidy, John S.; Dolphin, Annette C.

    2014-04-01

    Fragile X syndrome (FXS), the most common heritable form of mental retardation, is characterized by synaptic dysfunction. Synaptic transmission depends critically on presynaptic calcium entry via voltage-gated calcium (CaV) channels. Here we show that the functional expression of neuronal N-type CaV channels (CaV2.2) is regulated by fragile X mental retardation protein (FMRP). We find that FMRP knockdown in dorsal root ganglion neurons increases CaV channel density in somata and in presynaptic terminals. We then show that FMRP controls CaV2.2 surface expression by targeting the channels to the proteasome for degradation. The interaction between FMRP and CaV2.2 occurs between the carboxy-terminal domain of FMRP and domains of CaV2.2 known to interact with the neurotransmitter release machinery. Finally, we show that FMRP controls synaptic exocytosis via CaV2.2 channels. Our data indicate that FMRP is a potent regulator of presynaptic activity, and its loss is likely to contribute to synaptic dysfunction in FXS.

  1. The hydraulic geometry of narrow and deep channels; evidence for flow optimisation and controlled peatland growth

    Science.gov (United States)

    Nanson, Rachel A.; Nanson, Gerald C.; Huang, He Qing

    2010-04-01

    At-a-station and bankfull hydraulic geometry analyses of peatland channels at Barrington Tops, New South Wales, Australia, reveal adjustments in self-forming channels in the absence of sediment load. Using Rhodes ternary diagram, comparisons are made with hydraulic geometry data from self-forming channels carrying bedload in alluvial settings elsewhere. Despite constraints on channel depths caused at some locations by the restricted thickness of peat, most stations have cohesive, near-vertical, well-vegetated banks, and width/depth (w/d) ratios of ∼ 2 that are optimal for sediment-free flow. Because banks are strong, resist erosion and can stand nearly vertical, and depth is sometimes constrained, adjustments to discharge are accommodated largely by changes in velocity. These findings are consistent with the model of maximum flow efficiency and the overarching least action principle in open channels. The bankfull depth of freely adjusting laterally active channels in clastic alluvium is well known to be related to the thickness of floodplain alluvium and a similar condition appears to apply to these swamps that grow in situ and are formed almost entirely of organic matter. The thickness of peat in these swamps rarely exceeds that required to form a bankfull channel of optimum w/d ratio for the transport of sediment-free water. Swamp vegetation is highly dependent on proximity to the water table. To maintain a swamp-channel and associated floodplain system, the channels must flow with sufficient water much of the time; they not only offer an efficient morphology for flow but do so in a way that enables bankfull conditions to occur many times a year. They also prevent the swamp from growing above a level linked to the depth of the channel. Once the channel attains the most efficient cross section, further growth of the swamp vertically is restricted by enhanced flow velocities and limited flow depths. This means that the volume of peat in such swamps is determined

  2. Identification of motion from multi-channel EMG signals for control of prosthetic hand

    International Nuclear Information System (INIS)

    Full text: The authors in this paper propose an effective and efficient pattern recognition technique from four channel electromyogram (EMG) signals for control of multifunction prosthetic hand. Time domain features such as mean absolute value, number of zero crossings, number of slope sign changes and waveform length are considered for pattern recognition. The patterns are classified using simple logistic regression (SLR) technique and decision tree (DT) using J48 algorithm. In this study six specific hand and wrist motions are identified from the EMG signals obtained from ten different able-bodied. By considering relevant dominant features for pattern recognition, the processing time as well as memory space of the SLR and DT classifiers is found to be less in comparison with neural network (NN), k-nearest neighbour model 1 (kNN Model-1), k-nearest neighbour model 2 (kNN-Model-2) and linear discriminant analysis. The classification accuracy of SLR classifier is found to be 91 ± 1.9%. (author)

  3. Application of resin system for sand consolidation, mud-loss control, and channel repairing

    Energy Technology Data Exchange (ETDEWEB)

    Wasnik, A.; Mete, S.; Ghosh, B. [Maharashtra Inst. of Technology (India)

    2005-11-01

    Sand production is one of the major challenges facing oil well operators. A technique for sand consolidation and channel repairing with a resin system was described along with a methodology for placing a chemical casing during or after drilling a shale zone that is prone to caving. The methodology is intended to facilitate drilling with reduced mud weight, without reducing the hole size. The resin comprises a mixture of elastomers UF, MF and a suitable plasticizer to impart flexibility and impact resistance. The resin system includes both the resin and a hardener which is a mixture of 2 mild Lewis acids to control curing time. A special additive can be used to enhance surface bonding between the sand and resin. Experiments were then performed to examine the efficiency of resin (Asmid 603) with 7 different chemicals and resin Furmel 301 with Furmel catalyst as a curing modifier. The best combination for sand consolidation and chemical casing was found to be resin Asmid 603 with 0.6 per cent o-phosphoric acid at 80 degrees C and Furmel 301 with 2.5 per cent Furmel catalyst and CFNL with 0.6 per cent o-phosphoric acid. When this combination was used, the permeability was found to be nearly zero after consolidation of resin. The newly developed resin system costs one-third that of epoxy resins. Since it is water soluble, it is also easy to handle and environmentally sound. 15 refs., 2 tabs., 6 figs.

  4. Integrated Real-Time Control And Processing Systems For Multi-Channel Near-Infrared Spectroscopy Based Brain Computer Interfaces

    OpenAIRE

    Matthews, Fiachra

    2010-01-01

    This thesis outlines approaches to improve the signal processing and anal- ysis of Near-infrared spectroscopy (NIRS) based brain-computer interfaces (BCI). These approaches were developed in conjunction with the implemen- tation of a new customized exible multi-channel NIRS based BCI hardware system (Soraghan, 2010). Using a comparable functional imaging modality the assumptions on which NIRS-BCI have been reassessed, with regard to cognitive task selection, active area ...

  5. Using a terrestrial laser scanner to characterize vegetation-induced flow resistance in a controlled channel

    CERN Document Server

    Vinatier, Fabrice; Belaud, Gilles; Combemale, David

    2016-01-01

    Vegetation characteristics providing spatial heterogeneity at the channel reach scale can produce complex flow patterns and the relationship between plant patterns morphology and flow resistance is still an open question (Nepf 2012). Unlike experiments in laboratory, measuring the vegetation characteristics related to flow resistance on open channel in situ is difficult. Thanks to its high resolution and light weight, scanner lasers allow now to collect in situ 3D vegetation characteristics. In this study we used a 1064 nm usual Terrestrial Laser Scanner (TLS) located 5 meters at nadir above a 8 meters long equipped channel in order to both i) characterize the vegetation structure heterogeneity within the channel form a single scan (blockage factor, canopy height) and ii) to measure the 2D water level all over the channel during steady flow within a few seconds scan. This latter measuring system was possible thanks to an additive dispersive product sprinkled at the water surface. Vegetation characteristics an...

  6. Selection of Mother Wavelet Functions for Multi-Channel EEG Signal Analysis during a Working Memory Task

    Directory of Open Access Journals (Sweden)

    Noor Kamal Al-Qazzaz

    2015-11-01

    Full Text Available We performed a comparative study to select the efficient mother wavelet (MWT basis functions that optimally represent the signal characteristics of the electrical activity of the human brain during a working memory (WM task recorded through electro-encephalography (EEG. Nineteen EEG electrodes were placed on the scalp following the 10–20 system. These electrodes were then grouped into five recording regions corresponding to the scalp area of the cerebral cortex. Sixty-second WM task data were recorded from ten control subjects. Forty-five MWT basis functions from orthogonal families were investigated. These functions included Daubechies (db1–db20, Symlets (sym1–sym20, and Coiflets (coif1–coif5. Using ANOVA, we determined the MWT basis functions with the most significant differences in the ability of the five scalp regions to maximize their cross-correlation with the EEG signals. The best results were obtained using “sym9” across the five scalp regions. Therefore, the most compatible MWT with the EEG signals should be selected to achieve wavelet denoising, decomposition, reconstruction, and sub-band feature extraction. This study provides a reference of the selection of efficient MWT basis functions.

  7. Lithologic and hydrologic controls of mixed alluvial-bedrock channels in flood-prone fluvial systems: bankfull and macrochannels in the Llano River watershed, central Texas, USA

    Science.gov (United States)

    Heitmuller, Frank T.; Hudson, Paul F.; Asquith, William H.

    2015-01-01

    The rural and unregulated Llano River watershed located in central Texas, USA, has a highly variable flow regime and a wide range of instantaneous peak flows. Abrupt transitions in surface lithology exist along the main-stem channel course. Both of these characteristics afford an opportunity to examine hydrologic, lithologic, and sedimentary controls on downstream changes in channel morphology. Field surveys of channel topography and boundary composition are coupled with sediment analyses, hydraulic computations, flood-frequency analyses, and geographic information system mapping to discern controls on channel geometry (profile, pattern, and shape) and dimensions along the mixed alluvial-bedrock Llano River and key tributaries. Four categories of channel classification in a downstream direction include: (i) uppermost ephemeral reaches, (ii) straight or sinuous gravel-bed channels in Cretaceous carbonate sedimentary zones, (iii) straight or sinuous gravel-bed or bedrock channels in Paleozoic sedimentary zones, and (iv) straight, braided, or multithread mixed alluvial–bedrock channels with sandy beds in Precambrian igneous and metamorphic zones. Principal findings include: (i) a nearly linear channel profile attributed to resistant bedrock incision checkpoints; (ii) statistically significant correlations of both alluvial sinuosity and valley confinement to relatively high f (mean depth) hydraulic geometry values; (iii) relatively high b (width) hydraulic geometry values in partly confined settings with sinuous channels upstream from a prominent incision checkpoint; (iv) different functional flow categories including frequently occurring events (flood magnitude and noncohesive sandy sediments that collectively minimize development of alluvial bankfull indicators. Collectively, these findings indicate that mixed alluvial–bedrock channels exhibit first-order lithologic controls (lithologic resistance and valley confinement) of channel geometry, second

  8. A measurement of the top pair production cross-section in the dilepton channel using lepton plus track selection

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Corrinne Elaine; /UC, Santa Barbara

    2007-06-01

    Using 1.1 fb{sup -1} of data collected by the Collider Detector at Fermilab (CDF) from Run II of the Fermilab Tevatron, they measure the t{bar t} production cross section in events with two leptons, significant missing transverse energy, and {ge} 2 jets. As the Run II dataset grows, more stringent tests of Standard Model predictions for the top quark sector are becoming possible. The dilepton channel, where both top quarks decay t {yields} Wb {yields} {ell}{nu}b, is of particular interest due to its high purity even in the absence of a b jet 'tagging' requirement. Use of an isolated track as the second lepton significant increases the dilepton acceptance, at the price of some increase in background, particular from W + jets events where one of the jets is identified as a lepton. With the amount of data available, it has been possible to improve the estimate of the contribution from that background, reflected in a reduced systematic uncertainty. Assuming a branching ratio of BR(W {yields} {ell}{nu}) = 10.8% and a top mass of m{sub t} = 175 GeV/c{sup 2}, the measured cross-section is {sigma}(p{bar p} {yields} t{bar t}) = 8.3 {+-} 1.3(stat.) {+-} 0.7(syst.) {+-} 0.5(lumi.) pb. The result is consistent with the Standard Model prediction of 6.7{sub -0.9}{sup +0.7} pb and represents a significant improvement in precision over previous results using this selection.

  9. Vector control of wind turbine on the basis of the fuzzy selective neural net*

    Science.gov (United States)

    Engel, E. A.; Kovalev, I. V.; Engel, N. E.

    2016-04-01

    An article describes vector control of wind turbine based on fuzzy selective neural net. Based on the wind turbine system’s state, the fuzzy selective neural net tracks an maximum power point under random perturbations. Numerical simulations are accomplished to clarify the applicability and advantages of the proposed vector wind turbine’s control on the basis of the fuzzy selective neuronet. The simulation results show that the proposed intelligent control of wind turbine achieves real-time control speed and competitive performance, as compared to a classical control model with PID controllers based on traditional maximum torque control strategy.

  10. Communication: Determining the structure of the N2Ar van der Waals complex with laser-based channel-selected Coulomb explosion

    International Nuclear Information System (INIS)

    We experimentally reconstructed the structure of the N2Ar van der Waals complex with the technique of laser-based channel-selected Coulomb explosion imaging. The internuclear distance between the N2 center of mass and the Ar atom, i.e., the length of the van der Waals bond, was determined to be 3.88 Å from the two-body explosion channels. The angle between the van der Waals bond and the N2 principal axis was determined to be 90° from the three-body explosion channels. The reconstructed structure was contrasted with our high level ab initio calculations. The agreement demonstrated the potential application of laser-based Coulomb explosion in imaging transient molecular structure, particularly for floppy van der Waals complexes, whose structures remain difficult to be determined by conventional spectroscopic methods

  11. Channel-Reach Morphology in Formerly Glaciated, Mountain Streams: Controls and Prediction

    Science.gov (United States)

    Hassan, M. A.; Brardinoni, F.

    2006-12-01

    The spatial distribution of channel types in mountain drainage basins of coastal British Columbia is examined. Using field- and GIS-based data we show that the local channel slope and degree of colluvial-alluvial coupling imposed by the glacial valley morphology dictate the spatial organization of channel-reach morphology. In particular, the glacially-induced channel long profile generates characteristic sequences of channel reaches (with repetitions and inversions) that depart from the downstream succession distinctive of unglaciated mountain streams. For example, the presence of one hanging valley in the river long profile produces and separates two full successions of channel types a headmost one characterized by an ephemeral/seasonal hydrologic regime, and a downstream one, where water runoff is perennial. Exploratory scatter plots indicate that slope, shear stress, and relative roughness ensure best separation between reach types. At a confirmatory level, highest prediction of channel types is achieved by discriminant functions containing the same three variates. Success rates, depending on whether or not boulder-cascade reaches are grouped with step-pools, vary between 89% and 76%. Notwithstanding the glacially-inherited slope and the transient geomorphic dynamics of this landscape, similar to the case of unglaciated mountain streams, channel types are chiefly segregated by local slope (albeit characterized by significantly higher ranges), and to a lesser extent by shear stress and relative roughness. This outcome, while adding considerable strength to prior empirical knowledge, indicates that first-order physical conditions at which distinct channel states form are insensitive to very different landscape structures, hence histories.

  12. Selection of the 700 MWe PHWR pressuriser level control program through thermal hydraulic transient studies

    International Nuclear Information System (INIS)

    Full text: Conventionally the Pressuriser capacity, heater rating and the liquid level program are the important parameters to be optimized for reliable and trouble free operation of a water cooled nuclear power plants like Pressurised Heavy Water Reactor (PHWR). All these parameters are affected by the volume of the Primary Heat Transport (PHT) system and the corresponding swell/shrinkages anticipated. The magnitude of the swell/shrinkages depend on the rate of change of the PHT system fluid and structural temperatures for various transients. Based on these values the design of the PHT system pressure controller can be optimized. The 700 MWe PHWR PHT system design allows limited boiling towards the end of the coolant channel. The swell/shrinkages due to phase change are of larger magnitude but the pressure variation may be dampened during the two-phase PHT fluid condition with higher compressibility. The transition from single phase to two phase PHT system also needs to be analyzed for all the operational aspects such as the reactivity variation, process dynamics and the performance of the controllers. The secondary system behaviors also affect the PHT system volumetric changes due to thermal coupling. The performance of the selected Steam Generator Pressure Control Program (SGPC) also dictates the design of the PHT system pressure controller. The SGPC controller setting also has a considerable bearing on the performance of the PHT system pressure controller. Constant Boiler Pressure Program (CBPP) has been adopted design for this reactor. This program leads to higher values of shrinkages due to higher temperature difference between the PHT and the SGs. The design basis transient must account for the maximum credible swell/shrinkages anticipated/envisaged. The turbine trip transient and the reactor trip transient can form the basis with appropriate initial condition assumptions. The PHT system Instrumented Relief Valves sizing transient also can considered for the

  13. KV 7.4 channels participate in the control of rodent renal vascular resting tone

    DEFF Research Database (Denmark)

    Salomonsson, M.; Brasen, Jens Christian; Braunstein, Thomas Hartig;

    2015-01-01

    .2–5 stimulator flupirtine dose-dependently relaxed isolated rat interlobar arteries and increased (approx. 5%) RBF in vivo. The RBF responses to NE or Ang II administration were not affected by pre-treatment with XE991 or flupirtine. XE991 pre-treatment caused a minor augmentation of the acetylcholine......-induced increase in RBF, while flupirtine pre-treatment did not affect this response. Conclusion: It is concluded that KV7 channels, via nifedipine sensitive channels, have a role in the regulation of basal renal vascular tone. There is no indication that KV7 channels have an effect on agonist-induced renal...

  14. Synthetic Ciguatoxins Selectively Activate Nav1.8-derived Chimeric Sodium Channels Expressed in HEK293 Cells*

    OpenAIRE

    Yamaoka, Kaoru; Inoue, Masayuki; Miyazaki, Keisuke; Hirama, Masahiro; Kondo, Chie; Kinoshita, Eiji; Miyoshi, Hiroshi; Seyama, Issei

    2009-01-01

    The synthetic ciguatoxin CTX3C has been shown to activate tetrodotoxin (TTX)-sensitive sodium channels (Nav1.2, Nav1.4, and Nav1.5) by accelerating activation kinetics and shifting the activation curve toward hyperpolarization (Yamaoka, K., Inoue, M., Miyahara, H., Miyazaki, K., and Hirama, M. (2004) Br. J. Pharmacol. 142, 879–889). In this study, we further explored the effects of CTX3C on the TTX-resistant sodium channel Nav1.8. TTX-resistant channels have been s...

  15. Analytical modeling of mode selection and power control for underlay D2D communication in cellular networks

    KAUST Repository

    Elsawy, Hesham

    2014-11-01

    Device-to-device (D2D) communication enables the user equipments (UEs) located in close proximity to bypass the cellular base stations (BSs) and directly connect to each other, and thereby, offload traffic from the cellular infrastructure. D2D communication can improve spatial frequency reuse and energy efficiency in cellular networks. This paper presents a comprehensive and tractable analytical framework for D2D-enabled uplink cellular networks with a flexible mode selection scheme along with truncated channel inversion power control. The developed framework is used to analyze and understand how the underlaying D2D communication affects the cellular network performance. Through comprehensive numerical analysis, we investigate the expected performance gains and provide guidelines for selecting the network parameters.

  16. Optimal Selection of Sensing Channel in Cognitive Radio Network%认知无线电中感知信道的优化选择方法

    Institute of Scientific and Technical Information of China (English)

    叶军; 朱琦

    2012-01-01

    Spectrum sensing has been identified as a key requirement for dynamic spectrum allocation in cognitive radio network(CRN). Based on energy detection,this paper proposed an optimization method for channel selection in multi-user and multi-channel scenario. This method maximizes the normalized throughput that can be obtained by a CR user sensing a primary user's channel. The improved Hungarian algorithm is adopted to select the optimal channel for CR users. Simulation results show that the proposed optimization method can improve the overall normalized throughput comparing with the random channel selection method.%在认知无线电中,频谱感知是实现频谱动态接入的重要前提和核心环节,文中在多用户多信道环境下基于能量检测提出了一种感知信道优化选择的方法.该方法从最大化一个次用户感知一个主用户信道能获得的归一化吞吐量出发,在目标检测概率限制下,提出了基于改进的匈牙利算法进行感知信道选择的最优方法.仿真结果表明,与感知信道随机选择方法相比较,文中提出的方法可以大大提高整个次用户网络的归一化吞吐量.

  17. Ginsenoside Rb1 selectively inhibits the activity of L-type voltage-gated calcium channels in cultured rat hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Zhi-ying LIN; Li-min CHEN; Jing ZHANG; Xiao-dong PAN; Yuan-gui ZHU; Qin-yong YE; Hua-pin HUANG; Xiao-chun CHEN

    2012-01-01

    Aim:To investigate the effect of ginsenoside Rb1 on voltage-gated calcium currents in cultured rat hippocampal neurons and the modulatory mechanism.Methods:Cultured hippocampal neurons were prepared from Sprague Dawley rat embryos.Whole-cell configuration of the patchclamp technique was used to record the voltage-gated calcium currents (VGCCs)from the hippocampal neurons,and the effect of Rb1 was examined.Results:Rb1 (2-100 μmol/L)inhibited VGCCs in a concentration-dependent manner,and the current was mostly recovered upon wash-out.The specific L-type Ca2+ channel inhibitor nifedipine (10 μmol/L)occluded Rb1-induced inhibition on VGCCs.Neither the selective N-type Ca2+ channel blocker ω-conotoxin-GVlA (1 μmoVL),nor the selective P/Q-type Ca2+ channel blocker ωo-agatoxin IVA (30 nmol/L)diminished Rb1-sensitive VGCCs.Rb1 induced a leftward shift of the steady-state inactivation curve of Ica to a negative potential without affecting its activation kinetics or reversal potential in the I-V curve.The inhibitory effect of Rb1 was neither abolished by the adenylyl cyclase activator forskolin (10 μmol/L),nor by the PKA inhibitor H-89 (10 μmol/L).Conclusion:Ginsenoside Rb1 selectively inhibits the activity of L-type voltage-gated calcium channels,without affecting the N-type or P/Q-type Ca2+ channels in hippocampal neurons,cAMP-PKA signaling pathway is not involved in this effect.

  18. Training in control valves: selection criteria and designs under conditions of process

    International Nuclear Information System (INIS)

    This paper briefly describes training process analysis and selection of a control valve for different process conditions. Because the most common type of control valves is the design of guided globe valve type box. This paper focuses on this design and in selecting appropriate for such internal control valve. (Author)

  19. INDUSTRIAL BOILER RETROFIT FOR NOX CONTROL: COMBINED SELECTIVE NONCATALYTIC REDUCTION AND SELECTIVE CATALYTIC REDUCTION

    Science.gov (United States)

    The paper describes retrofitting and testing a 590 kW (2 MBtu/hr), oil-fired, three-pass, fire-tube package boiler with a combined selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR) system. The system demonstrated 85% nitrogen oxides (NOx) reduction w...

  20. Design and characterization of a highly selective peptide inhibitor of the small conductance calcium-activated K+ channel, SkCa2.

    Science.gov (United States)

    Shakkottai, V G; Regaya, I; Wulff, H; Fajloun, Z; Tomita, H; Fathallah, M; Cahalan, M D; Gargus, J J; Sabatier, J M; Chandy, K G

    2001-11-16

    Apamin-sensitive small conductance calcium-activated potassium channels (SKCa1-3) mediate the slow afterhyperpolarization in neurons, but the molecular identity of the channel has not been defined because of the lack of specific inhibitors. Here we describe the structure-based design of a selective inhibitor of SKCa2. Leiurotoxin I (Lei) and PO5, peptide toxins that share the RXCQ motif, potently blocked human SKCa2 and SKCa3 but not SKCa1, whereas maurotoxin, Pi1, Tskappa, and PO1 were ineffective. Lei blocked these channels more potently than PO5 because of the presence of Ala(1), Phe(2), and Met(7). By replacing Met(7) in the RXCQ motif of Lei with the shorter, unnatural, positively charged diaminobutanoic acid (Dab), we generated Lei-Dab(7), a selective SKCa2 inhibitor (K(d) = 3.8 nm) that interacts with residues in the external vestibule of the channel. SKCa3 was rendered sensitive to Lei-Dab(7) by replacing His(521) with the corresponding SKCa2 residue (Asn(367)). Intracerebroventricular injection of Lei-Dab(7) into mice resulted in no gross central nervous system toxicity at concentrations that specifically blocked SKCa2 homotetramers. Lei-Dab(7) will be a useful tool to investigate the functional role of SKCa2 in mammalian tissues. PMID:11527975

  1. Selecting controls for assessing interaction in nested case-control studies

    International Nuclear Information System (INIS)

    Two methods for selecting controls in nested case-control studies, matching on X and counter matching on X, are compared when interest is in interaction between a risk factor X measured in the full cohort and another risk factor Z measured only in the case-control sample. This is important because matching provides efficiency gains relative to random sampling when X is uncommon and the interaction is positive (greater than multiplicative), whereas counter matching is generally efficient compared to random sampling. Matching and counter matching were compared to each other and to random sampling of controls for dichotomous X and Z. Comparison was by simulation, using as an example a published study of radiation and other risk factors for breast cancer in the Japanese atomic-bomb survivors, and by asymptotic relative efficiency calculations for a wide range of parameters specifying the prevalence of X and Z as well as the levels of correlation and interaction between them. Focus was on analyses utilizing general models for the joint risk of X and Z. Counter-matching performed better than matching or random sampling in terms of efficiency for inference about interaction in the case of a rare risk factor X and uncorrelated risk factor Z. Further, more general, efficiency calculations demonstrated that counter-matching is generally efficient relative to matched case-control designs for studying interaction. Because counter-matched designs may be analyzed using standard statistical methods and allow investigation of confounding of the effect of X, whereas matched designs require a non-standard approach when fitting general risk models and do not allow investigating the adjusted risk of X, it is concluded that counter-matching on X can be a superior alternative to matching on X in nested case-control studies of interaction when X is known at the time of case-control sampling. (author)

  2. Selective inhibition of the Kir2 family of inward rectifier potassium channels by a small molecule probe: the discovery, SAR and pharmacological characterization of ML133

    Science.gov (United States)

    Wang, Hao-Ran; Wu, Meng; Yu, Haibo; Long, Shunyou; Stevens, Amy; Engers, Darren W.; Sackin, Henry; Daniels, J. Scott; Dawson, Eric S.; Hopkins, Corey R.; Lindsley, Craig W.; Li, Min; McManus, Owen B

    2011-01-01

    The Kir inward rectifying potassium channels have a broad tissue distribution and are implicated in a variety of functional roles. At least seven classes (Kir1 – Kir7) of structurally related inward rectifier potassium channels are known, and there are no selective small molecule tools to study their function. In an effort to develop selective Kir2.1 inhibitors, we performed a high-throughput screen (HTS) of more than 300,000 small molecules within the MLPCN for modulators of Kir2.1 function. Here we report one potent Kir2.1 inhibitor, ML133, which inhibits Kir2.1 with IC50 of 1.8 μM at pH 7.4 and 290 nM at pH 8.5, but exhibits little selectivity against other members of Kir2.x family channels. However, ML133 has no effect on Kir1.1 (IC50 > 300 μM), and displays weak activity for Kir4.1 (76 μM) and Kir7.1 (33 μM), making ML133 the most selective small molecule inhibitor of the Kir family reported to date. Due to the high homology within the Kir family, the channels share a common design of a pore region flanked by two transmembrane domains, identification of site(s) critical for isoform specificity would be an important basis for future development of more specific and potent Kir inhibitors. Using chimeric channels between Kir2.1 and Kir1.1 and site-directed mutagenesis, we have identified D172 and I176 within M2 segment of Kir2.1 as molecular determinants critical for the potency of ML133 mediated inhibition. Double mutation of the corresponding residues of Kir1.1 to those of Kir2.1 (N171D and C175I) transplants ML133 inhibition to Kir1.1. Together, the combination of a potent, Kir2 family selective inhibitor and identification of molecular determinants for the specificity provides both a tool and a model system to enable further mechanistic studies of modulation of Kir2 inward rectifier potassium channels. PMID:21615117

  3. Technical report: Metal concentrations in sediments, and selected biota from mine tailings in Gastineau Channel, Juneau, Alaska [Draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Hardrock gold mining occurred in Juneau from 1880 to 1944. Tailings and waste rock from the mines were deposited into Gastineau Channel and formed beaches along...

  4. Designing responsive pattern generators: stable heteroclinic channel cycles for modeling and control.

    Science.gov (United States)

    Horchler, Andrew D; Daltorio, Kathryn A; Chiel, Hillel J; Quinn, Roger D

    2015-04-01

    A striking feature of biological pattern generators is their ability to respond immediately to multisensory perturbations by modulating the dwell time at a particular phase of oscillation, which can vary force output, range of motion, or other characteristics of a physical system. Stable heteroclinic channels (SHCs) are a dynamical architecture that can provide such responsiveness to artificial devices such as robots. SHCs are composed of sequences of saddle equilibrium points, which yields exquisite sensitivity. The strength of the vector fields in the neighborhood of these equilibria determines the responsiveness to perturbations and how long trajectories dwell in the vicinity of a saddle. For SHC cycles, the addition of stochastic noise results in oscillation with a regular mean period. In this paper, we parameterize noise-driven Lotka-Volterra SHC cycles such that each saddle can be independently designed to have a desired mean sub-period. The first step in the design process is an analytic approximation, which results in mean sub-periods that are within 2% of the specified sub-period for a typical parameter set. Further, after measuring the resultant sub-periods over sufficient numbers of cycles, the magnitude of the noise can be adjusted to control the mean period with accuracy close to that of the integration step size. With these relationships, SHCs can be more easily employed in engineering and modeling applications. For applications that require smooth state transitions, this parameterization permits each state's distribution of periods to be independently specified. Moreover, for modeling context-dependent behaviors, continuously varying inputs in each state dimension can rapidly precipitate transitions to alter frequency and phase. PMID:25712192

  5. The Earliest Ion Channels

    Science.gov (United States)

    Pohorille, A.; Wilson, M. A.; Wei, C.

    2009-12-01

    Supplying protocells with ions required assistance from channels spanning their membrane walls. The earliest channels were most likely short proteins that formed transmembrane helical bundles surrounding a water-filled pore. These simple aggregates were capable of transporting ions with efficiencies comparable to those of complex, contemporary ion channels. Channels with wide pores exhibited little ion selectivity but also imposed only modest constraints on amino acid sequences of channel-forming proteins. Channels with small pores could have been selective but also might have required a more precisely defined sequence of amino acids. In contrast to modern channels, their protocellular ancestors had only limited capabilities to regulate ion flux. It is postulated that subsequent evolution of ion channels progressed primarily to acquire precise regulation, and not high efficiency or selectivity. It is further proposed that channels and the surrounding membranes co-evolved.

  6. Discrete control of TRPV4 channel function in the distal nephron by protein kinases A and C.

    Science.gov (United States)

    Mamenko, Mykola; Zaika, Oleg L; Boukelmoune, Nabila; Berrout, Jonathan; O'Neil, Roger G; Pochynyuk, Oleh

    2013-07-12

    We have recently documented that the Ca(2+)-permeable TRPV4 channel, which is abundantly expressed in distal nephron cells, mediates cellular Ca(2+) responses to elevated luminal flow. In this study, we combined Fura-2-based [Ca(2+)]i imaging with immunofluorescence microscopy in isolated split-opened distal nephrons of C57BL/6 mice to probe the molecular determinants of TRPV4 activity and subcellular distribution. We found that activation of the PKC pathway with phorbol 12-myristate 13-acetate significantly increased [Ca(2+)]i responses to flow without affecting the subcellular distribution of TRPV4. Inhibition of PKC with bisindolylmaleimide I diminished cellular responses to elevated flow. In contrast, activation of the PKA pathway with forskolin did not affect TRPV4-mediated [Ca(2+)]i responses to flow but markedly shifted the subcellular distribution of the channel toward the apical membrane. These actions were blocked with the specific PKA inhibitor H-89. Concomitant activation of the PKA and PKC cascades additively enhanced the amplitude of flow-induced [Ca(2+)]i responses and greatly increased basal [Ca(2+)]i levels, indicating constitutive TRPV4 activation. This effect was precluded by the selective TRPV4 antagonist HC-067047. Therefore, the functional status of the TRPV4 channel in the distal nephron is regulated by two distinct signaling pathways. Although the PKA-dependent cascade promotes TRPV4 trafficking and translocation to the apical membrane, the PKC-dependent pathway increases the activity of the channel on the plasma membrane. PMID:23709216

  7. Discrete Control of TRPV4 Channel Function in the Distal Nephron by Protein Kinases A and C*

    Science.gov (United States)

    Mamenko, Mykola; Zaika, Oleg L.; Boukelmoune, Nabila; Berrout, Jonathan; O'Neil, Roger G.; Pochynyuk, Oleh

    2013-01-01

    We have recently documented that the Ca2+-permeable TRPV4 channel, which is abundantly expressed in distal nephron cells, mediates cellular Ca2+ responses to elevated luminal flow. In this study, we combined Fura-2-based [Ca2+]i imaging with immunofluorescence microscopy in isolated split-opened distal nephrons of C57BL/6 mice to probe the molecular determinants of TRPV4 activity and subcellular distribution. We found that activation of the PKC pathway with phorbol 12-myristate 13-acetate significantly increased [Ca2+]i responses to flow without affecting the subcellular distribution of TRPV4. Inhibition of PKC with bisindolylmaleimide I diminished cellular responses to elevated flow. In contrast, activation of the PKA pathway with forskolin did not affect TRPV4-mediated [Ca2+]i responses to flow but markedly shifted the subcellular distribution of the channel toward the apical membrane. These actions were blocked with the specific PKA inhibitor H-89. Concomitant activation of the PKA and PKC cascades additively enhanced the amplitude of flow-induced [Ca2+]i responses and greatly increased basal [Ca2+]i levels, indicating constitutive TRPV4 activation. This effect was precluded by the selective TRPV4 antagonist HC-067047. Therefore, the functional status of the TRPV4 channel in the distal nephron is regulated by two distinct signaling pathways. Although the PKA-dependent cascade promotes TRPV4 trafficking and translocation to the apical membrane, the PKC-dependent pathway increases the activity of the channel on the plasma membrane. PMID:23709216

  8. Quality Control Method for a Micro-Nano-Channel Microfabricated Device

    Science.gov (United States)

    Grattoni, Alessandro; Ferrari, Mauro; Li, Xuewu

    2012-01-01

    A variety of silicon-fabricated devices is used in medical applications such as drug and cell delivery, and DNA and protein separation and analysis. When a fluidic device inlet is connected to a compressed gas reservoir, and the outlet is at a lower pressure, a gas flow occurs through the membrane toward the outside. The method relies on the measurement of the gas pressure over the elapsed time inside the upstream and downstream environments. By knowing the volume of the upstream reservoir, the gas flow rate through the membrane over the pressure drop can be calculated. This quality control method consists of measuring the gas flow through a device and comparing the results with a standard curve, which can be obtained by testing standard devices. Standard devices can be selected through a variety of techniques, both destructive and nondestructive, such as SEM, AFM, and standard particle filtration.

  9. Enhancement of Hippocampal Pyramidal Cell Excitability by the Novel Selective Slow-Afterhyperpolarization Channel Blocker 3-(Triphenylmethylaminomethyl)pyridine (UCL2077)

    OpenAIRE

    Shah, Mala M.; Javadzadeh-Tabatabaie, Mazyar; Benton, David C H; Ganellin, C. Robin; Haylett, Dennis G.

    2006-01-01

    The slow afterhyperpolarization (sAHP) in hippocampal neurons has been implicated in learning and memory. However, its precise role in cell excitability and central nervous system function has not been explicitly tested for 2 reasons: 1) there are, at present, no selective inhibitors that effectively reduce the underlying current in vivo or in intact in vitro tissue preparations, and 2) although it is known that a small conductance K+ channel that activates after a rise in [Ca2+]i underlies t...

  10. Insulin and IGF-1 activate Kir4.1/5.1 channels in cortical collecting duct principal cells to control basolateral membrane voltage.

    Science.gov (United States)

    Zaika, Oleg; Palygin, Oleg; Tomilin, Viktor; Mamenko, Mykola; Staruschenko, Alexander; Pochynyuk, Oleh

    2016-02-15

    Potassium Kir4.1/5.1 channels are abundantly expressed at the basolateral membrane of principal cells in the cortical collecting duct (CCD), where they are thought to modulate transport rates by controlling transepithelial voltage. Insulin and insulin-like growth factor-1 (IGF-1) stimulate apically localized epithelial sodium channels (ENaC) to augment sodium reabsorption in the CCD. However, little is known about their actions on potassium channels localized at the basolateral membrane. In this study, we implemented patch-clamp analysis in freshly isolated murine CCD to assess the effect of these hormones on Kir4.1/5.1 at both single channel and cellular levels. We demonstrated that K(+)-selective conductance via Kir4.1/5.1 is the major contributor to the macroscopic current recorded from the basolateral side in principal cells. Acute treatment with 10 μM amiloride (ENaC blocker), 100 nM tertiapin-Q (TPNQ; ROMK inhibitor), and 100 μM ouabain (Na(+)-K(+)-ATPase blocker) failed to produce a measurable effect on the macroscopic current. In contrast, Kir4.1 inhibitor nortriptyline (100 μM), but not fluoxetine (100 μM), virtually abolished whole cell K(+)-selective conductance. Insulin (100 nM) markedly increased the open probability of Kir4.1/5.1 and nortriptyline-sensitive whole cell current, leading to significant hyperpolarization of the basolateral membrane. Inhibition of the phosphatidylinositol 3-kinase cascade with LY294002 (20 μM) abolished action of insulin on Kir4.1/5.1. IGF-1 had similar stimulatory actions on Kir4.1/5.1-mediated conductance only when applied at a higher (500 nM) concentration and was ineffective at 100 nM. We concluded that both insulin and, to a lesser extent, IGF-1 activate Kir4.1/5.1 channel activity and open probability to hyperpolarize the basolateral membrane, thereby facilitating Na(+) reabsorption in the CCD. PMID:26632606

  11. Limited selection of sodium channel blocking toxin-producing bacteria from paralytic shellfish toxin-contaminated mussels (Aulacomya ater).

    Science.gov (United States)

    Vásquez, Mónica; Grüttner, Carol; Möeller, Blanca; Moore, Edward R B

    2002-01-01

    Paralytic shellfish toxins (PSTs) are sodium channel blocking (SCB) toxins, produced by cyanobacteria, as well as by marine dinoflagellates and their associated bacteria, and cause serious health and economic concern worldwide. In a previous study, approximately 70% of the bacteria enriched from PST-contaminated shellfish tissue and isolated on marine agar medium were observed to produce SCB toxins. In the study reported here, the high percentage of cultivable toxigenic bacteria is demonstrated to be obtained through a marked selection on marine agar medium. The cultivable as well as the total bacterial diversity associated with PST-contaminated shellfish collected from the Magallanes region in the south of Chile has been analysed. Approximately 80% of bacterial isolates, analysed by restriction analysis of PCR amplified ribosomal DNA (i.e., ARDRA fingerprinting), were limited to only two genotypic OTUs (operational taxonomic unit). Sequence determination and analysis of the 16S rDNA from representative isolates of both OTUs established them to be closely related to species of the Psychrobacter genus of the gamma-subclass of the Proteobacteria. The total bacterial diversity in the shellfish was further analysed, using a cultivation-independent strategy of extraction of total DNA from contaminated tissue, PCR-amplification of bacterial 16S rRNA genes, cloning of the PCR products and analysis of the cloned 16S rDNA sequence types by fingerprinting and sequencing. Only 2% of the cloned sequence types corresponded to species of the Psychrobacter genus. The 16S rDNA sequence types detected clustered with species of the y-Proteobacteria subclass, the Cytophaga-Flexibacter-Bacteroides (CFB), the Fusobacteria and the Firmicutes phyla. The level of diversity observed within the libraries of cloned 16S rDNA was markedly greater than that observed among isolates obtained through marine agar enrichment cultures from the same shellfish tissue. Additionally the predominant

  12. Analyzing the components of the free-energy landscape in a calcium selective ion channel by Widom’s particle insertion method

    OpenAIRE

    Boda, Dezső; Giri, Janhavi; Henderson, Douglas; Eisenberg, Bob; Gillespie, Dirk

    2011-01-01

    The selectivity filter of the L-type calcium channel works as a Ca2 + binding site with a very large affinity for Ca2 + versus Na+. Ca2 + replaces half of the Na+ ions in the filter even when these ions are present in 1 μM and 30 mM concentrations in the bath, respectively. The energetics of this strong selectivity is analyzed in this paper. We use Widom’s particle insertion method to compute the space-dependent profiles of excess chemical potential in our grand canonical Monte Carlo simulati...

  13. Polyhedral Interpolation for Optimal Reaction Control System Jet Selection

    Science.gov (United States)

    Gefert, Leon P.; Wright, Theodore

    2014-01-01

    An efficient algorithm is described for interpolating optimal values for spacecraft Reaction Control System jet firing duty cycles. The algorithm uses the symmetrical geometry of the optimal solution to reduce the number of calculations and data storage requirements to a level that enables implementation on the small real time flight control systems used in spacecraft. The process minimizes acceleration direction errors, maximizes control authority, and minimizes fuel consumption.

  14. Performance Analysis of Spectrum Handoff for Cognitive Radio Ad Hoc Networks without Common Control Channel under Homogeneous Primary Traffic

    CERN Document Server

    Song, Yi

    2011-01-01

    Cognitive radio (CR) technology is regarded as a promising solution to the spectrum scarcity problem. Due to the spectrum varying nature of CR networks, unlicensed users are required to perform spectrum handoffs when licensed users reuse the spectrum. In this paper, we study the performance of the spectrum handoff process in a CR ad hoc network under homogeneous primary traffic. We propose a novel three dimensional discrete-time Markov chain to characterize the process of spectrum handoffs and analyze the performance of unlicensed users. Since in real CR networks, a dedicated common control channel is not practical, in our model, we implement a network coordination scheme where no dedicated common control channel is needed. Moreover, in wireless communications, collisions among simultaneous transmissions cannot be immediately detected and the whole collided packets need to be retransmitted, which greatly affects the network performance. With this observation, we also consider the retransmissions of the collid...

  15. Selective suture cutting for control of astigmatism following cataract surgery

    OpenAIRE

    Bansal R; Gupta Amod; Grewal SPS

    1992-01-01

    Use of 10-0 monofilament nylon in ECCE cataract surgery leads to high with the rule astigmatism. Many intraoperative and post operative methods have been used to minimise post operative astigmatism. We did selective suture cutting in 38 consecutive patients. Mean keratometric astigmatism at three and six weeks post operative was 5.76 and 5.42 dioptres (D) respectively. 77.5% of eyes had astigmatism above 2 D. Selective suture cutting along the axis of the plus high cylinder was done af...

  16. Selection of References in Wind Turbine Model Predictive Control Design

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Hovgaard, Tobias

    2015-01-01

    a model predictive controller for a wind turbine. One of the important aspects for a tracking control problem is how to setup the optimal reference tracking problem, as it might be relevant to track, e.g., the three concurrent references: optimal pitch angle, optimal rotational speed, and optimal...... power. The importance if the individual references differ depending in particular on the wind speed. In this paper we investigate the performance of a reference tracking model predictive controller with two different setups of the used optimal reference signals. The controllers are evaluated using an...

  17. Delay-Sensitive Distributed Power and Transmission Threshold Control for S-ALOHA Network with Finite State Markov Fading Channels

    CERN Document Server

    Huang, Huang

    2009-01-01

    In this paper, we consider the delay-sensitive power and transmission threshold control design in S-ALOHA network with FSMC fading channels. The random access system consists of an access point with K competing users, each has access to the local channel state information (CSI) and queue state information (QSI) as well as the common feedback (ACK/NAK/Collision) from the access point. We seek to derive the delay-optimal control policy (composed of threshold and power control). The optimization problem belongs to the memoryless policy K-agent infinite horizon decentralized Markov decision process (DEC-MDP), and finding the optimal policy is shown to be computationally intractable. To obtain a feasible and low complexity solution, we recast the optimization problem into two subproblems, namely the power control and the threshold control problem. For a given threshold control policy, the power control problem is decomposed into a reduced state MDP for single user so that the overall complexity is O(NJ), where N a...

  18. Identification of (R)-N-(4-(4-methoxyphenyl)thiazol-2-yl)-1-tosylpiperidine-2-carboxamide, ML277, as a novel, potent and selective Kv7.1 (KCNQ1) potassium channel activator

    Science.gov (United States)

    Mattmann, Margrith E.; Yu, Haibo; Lin, Zhihong; Xu, Kaiping; Huang, Xiaofang; Long, Shunyou; Wu, Meng; McManus, Owen B.; Engers, Darren W.; Le, Uyen M.; Li, Min; Lindsley, Craig W.; Hopkins, Corey R.

    2012-01-01

    A high-throughput screen utilizing a depolarization-triggered thallium influx through KCNQ1 channels was developed and used to screen the MLSMR collection of over 300,000 compounds. An iterative medicinal chemistry approach was initiated and from this effort, ML277 was identified as a potent activator of KCNQ1 channels (EC50 = 260 nM). ML277 was shown to be highly selective against other KCNQ channels (>100-fold selectivity versus KCNQ2 and KCNQ4) as well as against the distantly related hERG potassium channel. PMID:22910039

  19. Feeders-TDMA: a distributed-control algorithm for satellite channel capacity assignment in a mixed traffic and faded environment

    OpenAIRE

    Celandroni, Nedo; Ferro, Erina; Potort?, Francesco

    1997-01-01

    This paper presents Faded Environments Effective Distributed Engineering Redundant Signalling (FEEDERS), an access scheme for sharing, in time division multiple access (TDMA) mode, the capacity of a satellite channel among a number of stations, on the basis of user demand, This scheme and its companion Distributed Allocation with Request In Fixed Slots (DRIFS), result from a study carried out by the authors on distributed-control protocols for geostationary satellite access. Both protocols de...

  20. Frequency Adaptive Selective Harmonic Control for Grid-Connected Inverters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Wang, Huai;

    2015-01-01

    SHC scheme consists of multiple parallel recursive (nk±m)-order (k = 0, 1, 2, . . ., and m ≤ n/2) harmonic control modules with independent control gains, which can be optimally weighted in accordance with the harmonic distribution. The hybrid SHC thus offers an optimal trade-off among cost...

  1. Control structure selection for energy integrated distillation column

    DEFF Research Database (Denmark)

    Hansen, J.E.; Jørgensen, Sten Bay

    1998-01-01

    different from what is usual for binary distillation columns. Further the heat pump enables disturbances to propagate faster through the system. The plant has six possible actuators of which three must be used to stabilize the system. Hereby three actuators are left for product purity control. An MILP...... screening method based on a linear state space model is used to determine economically optimal sets of controlled and manipulated variables. The generated sets of inputs and outputs are analysed with frequency dependent relative gain array (RGA), relative disturbance gain (RDG) and condition number (CN) to...... determine the best structure in terms disturbance rejection and setpoint tracking. The pairing and controller design are implemented and evaluated through nonlinear simulation. The suggested control structure is also qualitatively compared to a control structure applied experimentally. (C) 1998 Elsevier...

  2. Spacecraft flight control system design selection process for a geostationary communication satellite

    Science.gov (United States)

    Barret, C.

    1992-01-01

    The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Now, as we launch the Mars observer and the Cassini spacecraft, stability and control have become higher priorities. The flight control system design selection process is reviewed using as an example a geostationary communication satellite which is to have a life expectancy of 10 to 14 years. Disturbance torques including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques are assessed to quantify the disturbance environment so that the required compensating torque can be determined. Then control torque options, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, nutation dampers, inertia augmentation techniques, three-axis control, reactions control system (RCS), and RCS sizing, are considered. A flight control system design is then selected and preliminary stability criteria are met by the control gains selection.

  3. Thalamic Kv7 channels: pharmacological properties and activity control during noxious signal processing

    Science.gov (United States)

    Cerina, Manuela; Szkudlarek, Hanna J; Coulon, Philippe; Meuth, Patrick; Kanyshkova, Tatyana; Nguyen, Xuan Vinh; Göbel, Kerstin; Seidenbecher, Thomas; Meuth, Sven G; Pape, Hans-Christian; Budde, Thomas

    2015-01-01

    Background and Purpose The existence of functional Kv7 channels in thalamocortical (TC) relay neurons and the effects of the K+-current termed M-current (IM) on thalamic signal processing have long been debated. Immunocytochemical evidence suggests their presence in this brain region. Therefore, we aimed to verify their existence, pharmacological properties and function in regulating activity in neurons of the ventrobasal thalamus (VB). Experimental Approach Characterization of Kv7 channels was performed by combining in vitro, in vivo and in silico techniques with a pharmacological approach. Retigabine (30 μM) and XE991 (20 μM), a specific Kv7 channel enhancer and blocker, respectively, were applied in acute brain slices during electrophysiological recordings. The effects of intrathalamic injection of retigabine (3 mM, 300 nL) and/or XE991 (2 mM, 300 nL) were investigated in freely moving animals during hot-plate tests by recording behaviour and neuronal activity. Key Results Kv7.2 and Kv7.3 subunits were found to be abundantly expressed in TC neurons of mouse VB. A slow K+-current with properties of IM was activated by retigabine and inhibited by XE991. Kv7 channel activation evoked membrane hyperpolarization, a reduction in tonic action potential firing, and increased burst firing in vitro and in computational models. Single-unit recordings and pharmacological intervention demonstrated a specific burst-firing increase upon IM activation in vivo. A Kv7 channel-mediated increase in pain threshold was associated with fewer VB units responding to noxious stimuli, and increased burst firing in responsive neurons. Conclusions and Implications Kv7 channel enhancement alters somatosensory activity and may reflect an anti-nociceptive mechanism during acute pain processing. PMID:25684311

  4. Evolutionary adaptation of the amino acid and codon usage of the mosquito sodium channel following insecticide selection in the field mosquitoes.

    Directory of Open Access Journals (Sweden)

    Qiang Xu

    Full Text Available Target site insensitivity resulting from point mutations within the voltage-gated sodium channel of the insect nervous system is known to be of primary importance in the development of resistance to pyrethroid insecticides. This study shifts current research paradigms by conducting, for the first time, a global analysis of all the naturally occurring mutations, both nonsynonymous and synonymous mutations, as well as mutation combinations in the entire mosquito sodium channel of Culex quinquefasciatus and analyzing their evolutionary and heritable feature and roles in insecticide resistance. Through a systematic analysis of comparing nucleotide polymorphisms in the entire sodium channel cDNAs of individuals between susceptible and resistant mosquito strains, between field parental mosquitoes and their permethrin selected offspring, and among different mosquito groups categorized by their levels of tolerance to specific permethrin concentrations within and among the mosquito strains of the field parental strains and their permethrin selected offspring, 3 nonsynonymous (A(109S, L(982F, and W(1573R and 6 synonymous (L(852, G(891, A(1241, D(1245, P(1249, and G(1733 mutations were identified. The co-existence of all 9 mutations, both nonsynonymous and synonymous, and their homozygousity were found to be important factors for high levels of resistance. Our study, for the first time, provide a strong case demonstrating the co-existence of both nonsynonymous and synonymous mutations in the sodium channel of resistant mosquitoes in response to insecticide resistance and the inheritance of these mutations in the offspring of field mosquito strains following insecticide selection.

  5. Oxidation and Reduction Control of the Inactivation Gating of Torpedo ClC-0 Chloride Channels

    OpenAIRE

    Li, Yong; Yu, Wei-Ping; Lin, Chia-Wei; Chen, Tsung-Yu

    2005-01-01

    Oxidation and reduction (redox) are known to modulate the function of a variety of ion channels. Here, we report a redox regulation of the function of ClC-0, a chloride (Cl−) channel from the Torpedo electric organ. The study was motivated by the occasional observation of oocytes with hyperpolarization-activated Cl− current when these oocytes expressed ClC-0. We find that these atypical recording traces can be turned into typical ClC-0 current by incubating the oocyte in millimolar concentrat...

  6. System Identification and Control of an Irrigation Channel with a Tunnel

    OpenAIRE

    Bernhoff, Petra

    2008-01-01

    The demand on water is high but the supply of water is low due to the dry and warm climate in Australia. This is especially difficult for farmers that do not get enough water delivered in the irrigation channels which has dramatic consequences. A high percentage of the water lost in the channels can be saved if the systems are managed better. Using system identification techniques to develop a mathematical model which describes the dynamics in the irrigation system is a helpful tool for contr...

  7. Combining epidemiology and biomechanics in sports injury prevention research: a new approach for selecting suitable controls.

    Science.gov (United States)

    Finch, Caroline F; Ullah, Shahid; McIntosh, Andrew S

    2011-01-01

    Several important methodological issues need to be considered when designing sports injury case-control studies. Major design goals for case-control studies include the accounting for prior injury risk exposure, and optimal definitions of both cases and suitable controls are needed to ensure this. This article reviews methodological aspects of published sports injury case-control studies, particularly with regard to the selection of controls. It argues for a new approach towards selecting controls for case-control studies that draws on an interface between epidemiological and biomechanical concepts. A review was conducted to identify sport injury case-control studies published in the peer-review literature during 1985-2008. Overall, 32 articles were identified, of which the majority related to upper or lower extremity injuries. Matching considerations were used for control selection in 16 studies. Specific mention of application of biomechanical principles in the selection of appropriate controls was absent from all studies, including those purporting to evaluate the benefits of personal protective equipment to protect against impact injury. This is a problem because it could lead to biased conclusions, as cases and controls are not fully comparable in terms of similar biomechanical impact profiles relating to the injury incident, such as site of the impact on the body. The strength of the conclusions drawn from case-control studies, and the extent to which results can be generalized, is directly influenced by the definition and recruitment of cases and appropriate controls. Future studies should consider the interface between epidemiological and biomechanical concepts when choosing appropriate controls to ensure that proper adjustment of prior exposure to injury risk is made. To provide necessary guidance for the optimal selection of controls in case-control studies of interventions to prevent sports-related impact injury, this review outlines a new case-control

  8. G-protein- and cAMP-dependent L-channel gating modulation: a manyfold system to control calcium entry in neurosecretory cells.

    Science.gov (United States)

    Carbone, E; Carabelli, V; Cesetti, T; Baldelli, P; Hernández-Guijo, J M; Giusta, L

    2001-09-01

    Voltage-gated Ca2+ channels are crucial to the control of Ca2+ entry in neurosecretory cells. In the chromaffin cells of adrenal medulla, paracrinally or autocrinally released neurotransmitters induce profound changes in Ca2+ channel gating and Ca2+-dependent events controlling catecholamine secretion and cell activity. The generally held view of these processes is that neurotransmitter-induced modulation of the most widely expressed Ca2+ channels in these cells (N-, P/Q- and L-type) follows two distinct pathways: a direct membrane-delimited Gi/o-protein-induced inhibition of N- and P/Q-type and a remote cAMP-mediated facilitation of L-channels. Both actions depend on voltage, although with remarkably different molecular and kinetic aspects. Recent findings, however, challenge this simple scheme and suggest that L-channels do not require strong pre-pulses to be recruited or facilitated. They are available during normal depolarizations and may be tonically inhibited by Gi/o proteins activated by the released neurotransmitters. Like the N- and P/Q-channels, this autocrine modulation is localized to membrane microareas. Unlike N- and P/Q-channels, however, the inhibition of L-channels is largely independent of voltage and develops in parallel with cAMP-mediated potentiation of channel gating. As L-channels play a crucial role in the control of catecholamine release in chromaffin cells, the two opposite modulations mediated by Gi/o proteins and cAMP may represent an effective way to broaden the dynamic range of Ca2+ signals controlling exocytosis. Here, we review the basic features of this novel L-type channel inhibition comparing it to the well-established forms of L-channel potentiation and voltage-dependent facilitation. PMID:11680611

  9. Calcium microdomains near R-type calcium channels control the induction of presynaptic LTP at parallel fiber to Purkinje cell synapses

    OpenAIRE

    Myoga, Michael H.; Regehr, Wade G.

    2011-01-01

    R-type calcium channels in postsynaptic spines signal through functional calcium microdomains to regulate a calcium-calmodulin sensitive potassium channel that in turn regulates postsynaptic hippocampal LTP. Here we ask whether R-type calcium channels in presynaptic terminals also signal through calcium microdomains to control presynaptic LTP. We focus on presynaptic LTP at parallel fiber to Purkinje cell synapses in the cerebellum (PF-LTP), which is mediated by calcium/calmodulin-stimulated ...

  10. Evidence and control of inventory in selected company

    OpenAIRE

    BESEDOVÁ, Nela

    2010-01-01

    The diploma work deals with stock holding and inventory management in selected company. The main sources of information were specialized liturature and information provided by the company. The objective of this thesis was analyse, evaluation and improvement suggestion of stock holding and inventory management. The theoretic part is focused on stock holding and theory of inventory management. In the practical part is presented the company, process of production and structure of inventory.It ha...

  11. Response to selection under controlled environment versus natural selection in diverse regions across Canada

    Science.gov (United States)

    Red clover is a widely adaptable and productive forage legume species found in most temperate regions of the world. To date, specific selection techniques for identifying genotypes with superior persistence have not been successful in improving the general adaptation and the long-term persistence o...

  12. A Path Select Algorithm with Error Control Schemes and Energy Efficient Wireless Sensor Networks

    OpenAIRE

    Sandeep Dahiya; Amit Banga; Brahm Prakash Dahiya; Neha Kumari

    2012-01-01

    A wireless sensor network consists of a large number of sensor nodes that are spread densely to observe the phenomenon. The whole network lifetime relies on the lifetime of the each sensor node. If one node dies, it could lead to a separation of the sensor network. Also a multi hop structure and broadcast channel of wireless sensornecessitate error control scheme to achieve reliable data transmission. Automatic repeat request (ARQ) and forward error correction (FEC) are the key error control ...

  13. Control configuration selection for bilinear systems via generalised Hankel interaction index array

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Tahavori, Maryamsadat

    2015-01-01

    Decentralised and partially decentralised control strategies are very popular in practice. To come up with a suitable decentralised or partially decentralised control structure, it is important to select the appropriate input and output pairs for control design. This procedure is called control c...

  14. WSN Doubly Selective Channel Feature Matching Algorithm in Complex Application Environment%复杂应用环境下WSN双选信道特征配准算法

    Institute of Scientific and Technical Information of China (English)

    王云良; 刘贤锋

    2015-01-01

    无线传感器网络(WSN)在复杂应用环境下的双选信道特征配准算法研究,是对WSN数据管理的关键技术,WSN在数据发送中要经历时间和频率的双选择性衰落,为了在接收端被正确地接收,需要进行特征配准设计。传统方法采用普勒域单信道配准方法,特征配准效果不好。提出一种基于时延-多普勒域的时间和频率双选信道特征配准算法,满足复杂应用环境下的WSN数据管理需求。在线自适应调整信道配准控制误差,动态实时捕获信道传输数据,实现节点自适应优化分布,通过信道模型构建,对WSN进行时延-多普勒域表征,采用双选信道估计方法实现特征配准。仿真结果表明,该算法在复杂应用环境下,根据不同的调制信号,在不同带内信噪比下能实现对WSN的双选信道特征配准,准确率高于传统算法,抗噪性能较好,提高WSN的数据管理和调度能力,展示了本文算法的优越性能。%Wireless sensor network (WSN) of doubly selective channel feature matching algorithm in complex application environment is the key technology of WSN data management, doubly selective WSN to experience time and frequency in da⁃ta transmitting fading, in order to be correctly receive the signal, need for feature matching design. The traditional method used the Doppler domain single channel matching method, and feature registration effect is not good. A time and frequency doubly selective channel feature matching algorithm of time delay-Doppler domain is proposed for WSN data management, it meets the needs of complex application environment. Online adaptive adjustment channel registration error is controlled, dynamic real-time capture channel transmission data, realize node adaptive optimization distribution, through the construc⁃tion of channel models, delay Doppler domain characterization of WSN is estimated, feature matching using the doubly se

  15. An overview of historical channel adjustment and selected hydraulic values in the Lower Sabine and Lower Brazos River Basins, Texas and Louisiana

    Science.gov (United States)

    Heitmuller, Franklin T.; Greene, Lauren E.; John D. Gordon, John D.

    2010-01-01

    The Sabine and Brazos are alluvial rivers; alluvial rivers are dynamic systems that adjust their geometry in response to changes in streamflow (discharge) and sediment load. In fluvial geomorphology, the term 'channel adjustment' refers to river channel changes in three geometric dimensions: (1) channel slope (profile); (2) the outline or shape, such as meandering or braided, projected on a horizontal plane (planform); and (3) cross-sectional form (shape). The primary objective of the study was to investigate how the channel morphology of these rivers has changed in response to reservoirs and other anthropogenic disturbances that have altered streamflow and sediment load. The results of this study are expected to aid ecological assessments in the lower Sabine River and lower Brazos River Basins for the Texas Instream Flow Program. Starting in the 1920s, several dams have been constructed on the Sabine and Brazos Rivers and their tributaries, and numerous bridges have been built and sometimes replaced multiple times, which have changed the natural flow regime and reduced or altered sediment loads downstream. Changes in channel geometry over time can reduce channel conveyance and thus streamflow, which can have adverse ecological effects. Channel attributes including cross-section form, channel slope, and planform change were evaluated to learn how each river's morphology changed over many years in response to natural and anthropogenic disturbances. Climate has large influence on the hydrologic regimes of the lower Sabine and lower Brazos River Basins. Equally important as climate in controlling the hydrologic regime of the two river systems are numerous reservoirs that regulate downstream flow releases. The hydrologic regimes of the two rivers and their tributaries reflect the combined influences of climate, flow regulation, and drainage area. Historical and contemporary cross-sectional channel geometries at 15 streamflow-gaging stations in the lower Sabine and

  16. Impact of online channel use on customer revenues and costs to serve : Considering product portfolios and self-selection

    NARCIS (Netherlands)

    Gensler, S.; Leeflang, P.S.H.; Skiera, B.

    2012-01-01

    Developing a strategy for online channels requires knowledge of the effects of customers' online use on their revenue and cost to serve, which ultimately influence customer profitability. The authors theoretically discuss and empirically examine these effects. An empirical study of retail banking cu

  17. Block of CaV1.2 Channels by Gd3+ Reveals Preopening Transitions in the Selectivity Filter

    OpenAIRE

    Babich, Olga; Reeves, John; Shirokov, Roman

    2007-01-01

    Using the lanthanide gadolinium (Gd3+) as a Ca2+ replacing probe, we investigated the voltage dependence of pore blockage of CaV1.2 channels. Gd+3 reduces peak currents (tonic block) and accelerates decay of ionic current during depolarization (use-dependent block). Because diffusion of Gd3+ at concentrations used (

  18. 商业银行客户渠道选择偏好研究%Commercial Banks Customers' Preference for Channel Selection

    Institute of Scientific and Technical Information of China (English)

    张群; 董仲慧; 朱治安

    2012-01-01

    为了研究商业银行客户渠道选择偏好的影响因素,通过文献回顾,探讨了影响银行客户渠道选择偏好的易用性、便利性、风险性等关键因素,建立银行客户渠道选择偏好概念模型,通过调查数据运用lisrel8.7软件进行了实证分析,在此基础上,针对不同银行服务渠道(主要是柜台、ATM和网上银行),分析了这些影响因素是如何影响各个渠道的,并给出了相应的研究结论.%In order to study the factors influencing commercial banks customer' preference for channel selection,through literature review, this paper discusses Usability, Convenience, Risk, which are the key factors influencing customers' preference. Then the model of customers' channel selection preference was built. The model was demonstrated by using lisre 18. 7. Software and the data obtained in a survey. Based on the empirical analysis of the model, the paper examines how those factors influence each of bank service channels (mainly Branches, ATM and online Bank) ,with some conclusions reached.

  19. Achievable DoF and Its User Scaling Law for Opportunistic User Selection in a $K$-transmitter SIMO Interference Channel

    CERN Document Server

    Lee, Jung Hoon; Love, David J

    2011-01-01

    In this paper, we consider a $K$-transmitter single-input multiple-output (SIMO) interference channel (IC) where each transmitter has its own user group and serves one of the users in its group. When the number of receive antennas at each user is less than $K$ (i.e., $N_Rselection when the number of users per transmitter, $N$, goes to infinity. Using a geometric interpretation of the interfering channels, we propose opportunistic interference alignment (OIA) as a practical implementation of interference alignment. We find that a DoF of one per transmitter is achieved using the OIA scheme when the number of users is scaled as $N\\propto P^{\\alpha (K-N_R)}$ where $P$ is transmit power and $\\alpha$ is the relative path loss of the interfering channel in decibels. This result on the scaling law is extended and shown to be still valid for other user selection schemes such as the minimum interf...

  20. Reductions in Susceptibility of Channel Catfish (Ictalutus punctatus) to Enteric Septicemia of Catfish (ESC) Through Two Generations of Selection

    Science.gov (United States)

    Improvement of disease resistance in aquaculture species through selective breeding has had some success. At the USDA-ARS Catfish Genetics Research Unit, Stoneville, MS, a multitrait selection index was utilized to select for growth, carcass yield, and resistance to enteric septicemia of catfish (...

  1. Synthetic Ciguatoxins Selectively Activate Nav1.8-derived Chimeric Sodium Channels Expressed in HEK293 Cells*

    Science.gov (United States)

    Yamaoka, Kaoru; Inoue, Masayuki; Miyazaki, Keisuke; Hirama, Masahiro; Kondo, Chie; Kinoshita, Eiji; Miyoshi, Hiroshi; Seyama, Issei

    2009-01-01

    The synthetic ciguatoxin CTX3C has been shown to activate tetrodotoxin (TTX)-sensitive sodium channels (Nav1.2, Nav1.4, and Nav1.5) by accelerating activation kinetics and shifting the activation curve toward hyperpolarization (Yamaoka, K., Inoue, M., Miyahara, H., Miyazaki, K., and Hirama, M. (2004) Br. J. Pharmacol. 142, 879–889). In this study, we further explored the effects of CTX3C on the TTX-resistant sodium channel Nav1.8. TTX-resistant channels have been shown to be involved in transducing pain and related sensations (Akopian, A. N., Sivilotti, L., and Wood, J. N. (1996) Nature 379, 257–262). Thus, we hypothesized that ciguatoxin-induced activation of the Nav1.8 current would account for the neurological symptoms of ciguatera poisoning. We found that 0.1 μm CTX3C preferentially affected the activation process of the Nav1.8 channel compared with those of the Nav1.2 and Nav1.4 channels. Importantly, without stimulation, 0.1 μm CTX3C induced a large leakage current (IL). The conductance of the IL calculated relative to the maximum conductance (Gmax) was 10 times larger than that of Nav1.2 or Nav1.4. To determine the molecular domain of Nav1.8 responsible for conferring higher sensitivity to CTX3C, we made two chimeric constructs from Nav1.4 and Nav1.8. Chimeras containing the N-terminal half of Nav1.8 exhibited a large response similar to wild-type Nav1.8, indicating that the region conferring high sensitivity to ciguatoxin action is located in the D1 or D2 domains. PMID:19164297

  2. Pulse Selection Control for the IR FEL Photocathode Drive Laser

    Science.gov (United States)

    Jordan, K.; Evans, R.; Garza, O.; Hill, R.; Shinn, M.; Song, J.; Venhaus, D.

    1997-05-01

    The method for current control of the photocathode source is described. This device allows remote control of drive laser output pulses for resulting beam currents of less than 1 microamp to full current of 5 milliamps. The low current modes are accomplished by counting discrete micropulses and gating electro-optical cells. The higher current modes are done by varying both the photons per pulse and the frequency of the laser output pulses. Programmable Logic Devices (PLDs) provide the choice in micropulses per macropulse and the macropulse frequency. All macropulses are line locked to 60 Hz and have the ability to be slewed through a line cycle in discrete steps.

  3. Effectiveness Using Circular Fibre Steel Flap Gate As a Control Structure Towards the Hydraulic Characteristics in Open Channel

    Science.gov (United States)

    Adib, M. R. M.; Amirza, A. R. M.; Wardah, T.; Junaidah, A.

    2016-07-01

    Hydraulic control gate structure plays an important role in regulating the flow of water in river, canal or water reservoir. One of the most appropriate structures in term of resolving the problem of flood occured is the construction of circular fibre steel flap gate. Therefore, an experiment has been conducted by using an open channel model at laboratory. In this case, hydraulic jump and backwater were the method to determined the hydraulic characteristics of circular fibre steel flap gate in an open channel model. From the experiment, the opening angle of flap gate can receive discharges with the highest flow rate of 0.035 m3/s with opening angle was 47°. The type of jump that occurs at the slope of 1/200 for a distance of 5.0 m is a standing jump or undulating wave. The height of the backwater can be identified based on the differences of specific force which is specific force before jump, F1 and specific force after jump, F2 from the formation of backwater. Based on the research conducted, the tendency of incident backwater wave occurred was high in every distance of water control location from water inlet is flap slope and the slope of 1/300 which is 0.84 m/s and 0.75 m/s of celerity in open channel model.

  4. Exploring geomorphic controls on fish bioenergetics in mountain streams: linkages between channel morphology and rearing habitat for cutthroat trout

    Science.gov (United States)

    Cienciala, P.; Hassan, M. A.

    2013-12-01

    Landscape heterogeneity constitutes an important control on spatial distribution of habitat for living organisms, at a range of spatial scales. For example, spatial variation in geomorphic processes can spatially structure populations as well as entire communities, and affect various ecosystem processes. We have coupled a 2D hydrodynamic model with a bioenergetic model to study the effects of various channel morphologies and bed textures on rearing habitat for coastal cutthroat trout (Oncorhynchus clarki clarki) in four reaches of a mountain stream. The bioenergetic model uses energy conservation principle to calculate energy budget for fish at any point of the study domain, given a set of relevant local conditions. Specifically, the energy intake is a function of food availability (invertebrate drift) while the energy expenditure occurs through, for example, basal metabolism and swimming to hold position against the flow. Channel morphology and bed texture, through their influence on channel hydraulics, can exert strong control on the spatial pattern of both food flux and swimming cost for drift-feeding fish. Therefore, the coupled hydrodynamic and bioenergetic models, parameterized using an extensive field data set, enabled us to explore mechanistic linkages between geomorphic properties of the study reaches, food resource availability, and the energetic profitability of rearing habitat for different age-classes at both between- and within-reach spatial scales.

  5. Full equations utilities (FEQUTL) model for the approximation of hydraulic characteristics of open channels and control structures during unsteady flow

    Science.gov (United States)

    Franz, Delbert D.; Melching, Charles S.

    1997-01-01

    The Full EQuations UTiLities (FEQUTL) model is a computer program for computation of tables that list the hydraulic characteristics of open channels and control structures as a function of upstream and downstream depths; these tables facilitate the simulation of unsteady flow in a stream system with the Full Equations (FEQ) model. Simulation of unsteady flow requires many iterations for each time period computed. Thus, computation of hydraulic characteristics during the simulations is impractical, and preparation of function tables and application of table look-up procedures facilitates simulation of unsteady flow. Three general types of function tables are computed: one-dimensional tables that relate hydraulic characteristics to upstream flow depth, two-dimensional tables that relate flow through control structures to upstream and downstream flow depth, and three-dimensional tables that relate flow through gated structures to upstream and downstream flow depth and gate setting. For open-channel reaches, six types of one-dimensional function tables contain different combinations of the top width of flow, area, first moment of area with respect to the water surface, conveyance, flux coefficients, and correction coefficients for channel curvilinearity. For hydraulic control structures, one type of one-dimensional function table contains relations between flow and upstream depth, and two types of two-dimensional function tables contain relations among flow and upstream and downstream flow depths. For hydraulic control structures with gates, a three-dimensional function table lists the system of two-dimensional tables that contain the relations among flow and upstream and downstream flow depths that correspond to different gate openings. Hydraulic control structures for which function tables containing flow relations are prepared in FEQUTL include expansions, contractions, bridges, culverts, embankments, weirs, closed conduits (circular, rectangular, and pipe

  6. Neuronal polarity selection by topography-induced focal adhesion control.

    Science.gov (United States)

    Ferrari, Aldo; Cecchini, Marco; Serresi, Michela; Faraci, Paolo; Pisignano, Dario; Beltram, Fabio

    2010-06-01

    Interaction between differentiating neurons and the extracellular environment guides the establishment of cell polarity during nervous system development. Developing neurons read the physical properties of the local substrate in a contact-dependent manner and retrieve essential guidance cues. In previous works we demonstrated that PC12 cell interaction with nanogratings (alternating lines of ridges and grooves of submicron size) promotes bipolarity and alignment to the substrate topography. Here, we investigate the role of focal adhesions, cell contractility, and actin dynamics in this process. Exploiting nanoimprint lithography techniques and a cyclic olefin copolymer, we engineered biocompatible nanostructured substrates designed for high-resolution live-cell microscopy. Our results reveal that neuronal polarization and contact guidance are based on a geometrical constraint of focal adhesions resulting in an angular modulation of their maturation and persistence. We report on ROCK1/2-myosin-II pathway activity and demonstrate that ROCK-mediated contractility contributes to polarity selection during neuronal differentiation. Importantly, the selection process confined the generation of actin-supported membrane protrusions and the initiation of new neurites at the poles. Maintenance of the established polarity was independent from NGF stimulation. Altogether our results imply that focal adhesions and cell contractility stably link the topographical configuration of the extracellular environment to a corresponding neuronal polarity state. PMID:20304485

  7. Selecting protective devices for use in rectified control current circuits

    Energy Technology Data Exchange (ETDEWEB)

    Savin, S.N.; Krichevskaya, L.Z.

    1982-11-01

    Power supplies are in widespread use at 35-110 kV substations as sources of control current. These power supplies are rectifying devices which consist of an intermediate transformer with a three-phase bridge rectifier. The advantages of the various types of power supplies are discussed.

  8. Optimal Selective Harmonic Control for Power Harmonics Mitigation

    DEFF Research Database (Denmark)

    Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede;

    2015-01-01

    of power harmonics. The proposed optimal SHC is of hybrid structure: all recursive SHC modules with weighted gains are connected in parallel. It bridges the real “nk+-m order RC” and the complex “parallel structure RC”. Compared to other IMP based control solutions, it offers an optimal trade...

  9. Disposal of waste channels and control rods and radioactive waste; Gestion de canales usados y barras de control como residuos radiactivos

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Alvarez, L.

    2015-07-01

    Iberdrola and ENRESA are jointly developing a project for the characterization and conditioning of around 200 control rods and 70 used channel from Cofrentes Nuclear Power Plant. This treatment line for high level waste with a radiologic inventory that avoids using the El Cabril low level waste repository is new in Spain and incorporates specific features like the option to carry on with the conditioning stage prior to having a licensed package and available storage facility for this type of waste. (Author)

  10. Flexible controlled joint remote preparation of an arbitrary two-qubit state via non-maximally entangled quantum channels

    Science.gov (United States)

    Bich Cao, Thi; Hop Nguyen, Van; Nguyen, Ba An

    2016-06-01

    Transferring a quantum state from one location to another without physically sending the state itself through open space is a special global task that can only be carried out thanks to the laws of nature, namely the principles of quantum mechanics. In this work, we devise protocols for two senders to jointly prepare the most general two-qubit state for a receiver under the supervision of a controller by using three different types of quantum channels, all of which are non-maximally entangled. First, we propose the schemes to produce the quantum channels concerned, and then we present the concrete steps required to execute the protocols, highlighting the issue of why shared non-maximal entanglement is intentionally used instead of maximal entanglement.

  11. Goal selection versus process control while learning to use a brain-computer interface

    Science.gov (United States)

    Royer, Audrey S.; Rose, Minn L.; He, Bin

    2011-06-01

    A brain-computer interface (BCI) can be used to accomplish a task without requiring motor output. Two major control strategies used by BCIs during task completion are process control and goal selection. In process control, the user exerts continuous control and independently executes the given task. In goal selection, the user communicates their goal to the BCI and then receives assistance executing the task. A previous study has shown that goal selection is more accurate and faster in use. An unanswered question is, which control strategy is easier to learn? This study directly compares goal selection and process control while learning to use a sensorimotor rhythm-based BCI. Twenty young healthy human subjects were randomly assigned either to a goal selection or a process control-based paradigm for eight sessions. At the end of the study, the best user from each paradigm completed two additional sessions using all paradigms randomly mixed. The results of this study were that goal selection required a shorter training period for increased speed, accuracy, and information transfer over process control. These results held for the best subjects as well as in the general subject population. The demonstrated characteristics of goal selection make it a promising option to increase the utility of BCIs intended for both disabled and able-bodied users.

  12. Identification and analysis of genome-wide SNPs provide insight into signatures of selection and domestication in channel catfish (Ictalurus punctatus.

    Directory of Open Access Journals (Sweden)

    Luyang Sun

    Full Text Available Domestication and selection for important performance traits can impact the genome, which is most often reflected by reduced heterozygosity in and surrounding genes related to traits affected by selection. In this study, analysis of the genomic impact caused by domestication and artificial selection was conducted by investigating the signatures of selection using single nucleotide polymorphisms (SNPs in channel catfish (Ictalurus punctatus. A total of 8.4 million candidate SNPs were identified by using next generation sequencing. On average, the channel catfish genome harbors one SNP per 116 bp. Approximately 6.6 million, 5.3 million, 4.9 million, 7.1 million and 6.7 million SNPs were detected in the Marion, Thompson, USDA103, Hatchery strain, and wild population, respectively. The allele frequencies of 407,861 SNPs differed significantly between the domestic and wild populations. With these SNPs, 23 genomic regions with putative selective sweeps were identified that included 11 genes. Although the function for the majority of the genes remain unknown in catfish, several genes with known function related to aquaculture performance traits were included in the regions with selective sweeps. These included hypoxia-inducible factor 1β. HIFιβ.. and the transporter gene ATP-binding cassette sub-family B member 5 (ABCB5. HIF1β. is important for response to hypoxia and tolerance to low oxygen levels is a critical aquaculture trait. The large numbers of SNPs identified from this study are valuable for the development of high-density SNP arrays for genetic and genomic studies of performance traits in catfish.

  13. Cooperative jamming power control to enhance secrecy communications of AF Relaying systems for Rayleigh fading channel

    KAUST Repository

    Park, Kihong

    2012-09-01

    In this paper, we investigate secrecy communications in two-hop wireless relaying networks which consist of one source, one amplify-and-forward (AF) relay, one legitimate destination, and one eavesdropper. To prevent the eavesdropper from intercepting the source message, we make the destination send the intended noise to the AF relay during the first phase. This is referred to as cooperative jamming. According to the channel information at the destination, we address two types of jamming power allocation; (i) rate-optimal power allocation and (ii) outage-optimal power allocation. More specifically, without the instantaneous channel knowledge for the eavesdropper side, the outage probability of the secrecy rate is minimized with respect to the intended noise power level. We show that the outage-optimal allocation gives almost the same outage probability as the rateoptimal one. In addition, the jamming power consumption can be significantly reduced compared to the fixed and rate-optimal power allocation methods. © 2012 IEEE.

  14. Kinetically controlled E-selective catalytic olefin metathesis.

    Science.gov (United States)

    Nguyen, Thach T; Koh, Ming Joo; Shen, Xiao; Romiti, Filippo; Schrock, Richard R; Hoveyda, Amir H

    2016-04-29

    A major shortcoming in olefin metathesis, a chemical process that is central to research in several branches of chemistry, is the lack of efficient methods that kinetically favor E isomers in the product distribution. Here we show that kinetically E-selective cross-metathesis reactions may be designed to generate thermodynamically disfavored alkenyl chlorides and fluorides in high yield and with exceptional stereoselectivity. With 1.0 to 5.0 mole % of a molybdenum-based catalyst, which may be delivered in the form of air- and moisture-stable paraffin pellets, reactions typically proceed to completion within 4 hours at ambient temperature. Many isomerically pure E-alkenyl chlorides, applicable to catalytic cross-coupling transformations and found in biologically active entities, thus become easily and directly accessible. Similarly, E-alkenyl fluorides can be synthesized from simpler compounds or more complex molecules. PMID:27126041

  15. Material selection and corrosion control practices in petroleum production

    International Nuclear Information System (INIS)

    The intent of this paper is to review briefly the current state of the art and to discuss some of the anticipated future oil and gas drilling and production activities which may challenge the materials selection and corrosion technologies. The current state of art discussions in this paper have been augmented by providing a list of references so that interested engineers may delve into each subject in more detail as desired. The technological areas which appear to require additional input to meet future needs include high strength tubular goods for sour gas service, corrosion resistant high strength alloys, definition of the effects of pressure, temperature, and fluid composition on corrosion behavior, and fatigue properties of various steels in seawater

  16. Control room annunciation - problem assessment and selection of improvement priorities

    International Nuclear Information System (INIS)

    In 1997, Pickering B undertook a project to examine current annunciation practice and identify improvement opportunities and priorities. The objectives and scope of the study were to: document the deficiencies with control room annunciation and the subsequent operational and financial impacts to station operations, develop an operations-based definition of the requirements for annunciation to adequately support control room staff, propose annunciation improvements based on a comparison of the annunciation deficiencies identified and the operational needs to be met, assess the relative operational impact, and financial benefits and costs of the improvement initiatives proposed, and recommend annunciation improvement priorities that offer a mix of operational and financial return for improvement investment. This paper discusses the rationale for the project, outlines the approaches applied in achieving the assessment objectives, reviews the key assessment findings and describes the improvement initiatives recommended. (author)

  17. CNTRICS final animal model task selection: Control of attention

    OpenAIRE

    Lustig, C.; Kozak, R; Sarter, M.; Young, J.W.; Robbins, T. W.

    2013-01-01

    Schizophrenia is associated with impaired attention. The top-down control of attention, defined as the ability to guide and refocus attention in accordance with internal goals and representations, was identified by the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) initiative as an important construct for task development and research. A recent CNTRICS meeting identified three tasks commonly used with rodent models as having high construct validity a...

  18. Attosecond-recollision-controlled selective fragmentation of polyatomic molecules

    OpenAIRE

    Xie, Xinhua; Doblhoff-Dier, Katharina; Roither, Stefan; Schöffler, Markus S.; Kartashov, Daniil; Xu, Huailiang; Rathje, Tim; Paulus, Gerhard G.; Baltuška, Andrius; Gräfe, Stefanie; Kitzler, Markus

    2012-01-01

    Control over various fragmentation reactions of a series of polyatomic molecules (acetylene, ethylene, 1,3-butadiene) by the optical waveform of intense few-cycle laser pulses is demonstrated experimentally. We show both experimentally and theoretically that the responsible mechanism is inelastic ionization from inner-valence molecular orbitals by recolliding electron wavepackets, whose recollision energy in few-cycle ionizing laser pulses strongly depends on the optical waveform. Our work de...

  19. Optimizing weight control in diabetes: antidiabetic drug selection

    OpenAIRE

    Kalra, S.; Kalra, B; Unnikrishnan, AG; N. Agrawal; Kumar, S.

    2010-01-01

    Clinical question Which antidiabetic drugs provide optimal weight control in patients with type 2 diabetes? Results Metformin reduces weight gain, and may cause weight loss, when given alone or in combination with other drugs. Pioglitazone and rosiglitazone use is associated with weight gain. Use of the glucagon-like peptide-1 (GLP-1) analogs, liraglutide and exenatide, is associated with weight loss. Dipeptidyl peptidase-4 (DPP-4) inhibitors are considered weight-neutral. Results with insuli...

  20. Lithic Resource Control and Economic Change in the Santa Barbara Channel Region

    OpenAIRE

    Arnold, Jeanne E

    1990-01-01

    The territory occupied by the Chumash and their prehistoric predecessors encompassed the northern Channel Islands and a large mainland area extending from modern San Luis Obispo to Malibu and inland to the western margin of the San Joaquin Valley. The region is characterized by significant physiographic, biotic, and geological diversity. Each of these dimensions of variability has implications for the forms of human adaptation that developed during the course of several millennia of prehistor...