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Sample records for central channel residues

  1. Channeling the Central Dogma.

    Science.gov (United States)

    Calabrese, Ronald L

    2014-05-21

    How do neurons and networks achieve their characteristic electrical activity, regulate this activity homeostatically, and yet show population variability in expression? In this issue of Neuron, O'Leary et al. (2014) address some of these thorny questions in this theoretical analysis that starts with the Central Dogma.

  2. Tuning the affinity of anion binding sites in porin channels with negatively charged residues: molecular details for OprP.

    Science.gov (United States)

    Modi, Niraj; Bárcena-Uribarri, Iván; Bains, Manjeet; Benz, Roland; Hancock, Robert E W; Kleinekathöfer, Ulrich

    2015-02-20

    The cell envelope of the Gram negative opportunistic pathogen Pseudomonas aeruginosa is poorly permeable to many classes of hydrophilic molecules including antibiotics due to the presence of the narrow and selective porins. Here we focused on one of the narrow-channel porins, that is, OprP, which is responsible for the high-affinity uptake of phosphate ions. Its two central binding sites for phosphate contain a number of positively charged amino acids together with a single negatively charged residue (D94). The presence of this negatively charged residue in a binding site for negatively charged phosphate ions is highly surprising due to the potentially reduced binding affinity. The goal of this study was to better understand the role of D94 in phosphate binding, selectivity, and transport using a combination of mutagenesis, electrophysiology, and free-energy calculations. The presence of a negatively charged residue in the binding site is critical for this specific porin OprP as emphasized by the evolutionary conservation of such negatively charged residue in the binding site of several anion-selective porins. Mutations of D94 in OprP to any positively charged or neutral residue increased the binding affinity of phosphate for OprP. Detailed analysis indicated that this anionic residue in the phosphate binding site of OprP, despite its negative charge, maintained energetically favorable phosphate binding sites in the central region of the channel and at the same time decreased residence time thus preventing excessively strong binding of phosphate that would oppose phosphate flux through the channel. Intriguingly mutations of D94 to positively charged residues, lysine and arginine, resulted in very different binding affinities and free energy profiles, indicating the importance of side chain conformations of these positively charged residues in phosphate binding to OprP.

  3. Ion channels as drug targets in central nervous system disorders.

    Science.gov (United States)

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

    2013-01-01

    Ion channel targeted drugs have always been related with either the central nervous system (CNS), the peripheral nervous system, or the cardiovascular system. Within the CNS, basic indications of drugs are: sleep disorders, anxiety, epilepsy, pain, etc. However, traditional channel blockers have multiple adverse events, mainly due to low specificity of mechanism of action. Lately, novel ion channel subtypes have been discovered, which gives premises to drug discovery process led towards specific channel subtypes. An example is Na(+) channels, whose subtypes 1.3 and 1.7-1.9 are responsible for pain, and 1.1 and 1.2 - for epilepsy. Moreover, new drug candidates have been recognized. This review is focusing on ion channels subtypes, which play a significant role in current drug discovery and development process. The knowledge on channel subtypes has developed rapidly, giving new nomenclatures of ion channels. For example, Ca(2+)s channels are not any more divided to T, L, N, P/Q, and R, but they are described as Ca(v)1.1-Ca(v)3.3, with even newer nomenclature α1A-α1I and α1S. Moreover, new channels such as P2X1-P2X7, as well as TRPA1-TRPV1 have been discovered, giving premises for new types of analgesic drugs.

  4. Present-day dynamic and residual topography in Central Anatolia

    Science.gov (United States)

    Şengül Uluocak, Ebru; Pysklywec, Russell; Göǧüş, Oǧuz H.

    2016-09-01

    The Central Anatolian orogenic plateau is represented by young volcanism, rapid plateau uplift and distinctive (past and active) tectonic deformation. In this study, we consider observational data in terms of regional present-day geodynamics in the region. The residual topography of Central Anatolia was derived to define the regional isostatic conditions according to Airy isostasy and infer the potential role of `dynamic topography'. 2-D thermomechanical forward models for coupled mantle-lithosphere flow/deformation were conducted along an N-S directional profile through the region (e.g. northern/Pontides, interior and southern/Taurides). These models were based on seismic tomography data that provide estimates about the present-day mantle thermal structure beneath the Anatolian plate. We compare the modelling results with calculated residual topography and independent data sets of geological deformation, gravity and high surface heat flow/widespread geothermal activity. Model results suggest that there is ˜1 km of mantle flow induced dynamic topography associated with the sublithospheric flow driven by the seismically inferred mantle structure. The uprising mantle may have also driven the asthenospheric source of volcanism in the north (e.g. Galatia volcanic province) and the Cappadocia volcanic province in the south while elevating the surface in the last 10 Myr. Our dynamic topography calculations emphasize the role of vertical forcing under other orogenic plateaux underlain by relatively thin crust and low-density asthenospheric mantle.

  5. Do cysteine residues regulate transient receptor potential canonical type 6 (TRPC6) channel protein expression?

    DEFF Research Database (Denmark)

    Thilo, Florian; Liu, Ying; Krueger, Katharina;

    2012-01-01

    The regulation of calcium influx through transient receptor potential canonical type 6 channel is mandatory for the activity of human monocytes. We submit the first evidence that cysteine residues of homocysteine or acetylcysteine affect TRPC6 expression in human monocytes. We observed that patie......The regulation of calcium influx through transient receptor potential canonical type 6 channel is mandatory for the activity of human monocytes. We submit the first evidence that cysteine residues of homocysteine or acetylcysteine affect TRPC6 expression in human monocytes. We observed...... to control conditions. We therefore hypothesize that cysteine residues increase TRPC6 channel protein expression in humans....

  6. Protein thermal denaturation is modulated by central residues in the protein structure network.

    Science.gov (United States)

    Souza, Valquiria P; Ikegami, Cecília M; Arantes, Guilherme M; Marana, Sandro R

    2016-03-01

    Network structural analysis, known as residue interaction networks or graphs (RIN or RIG, respectively) or protein structural networks or graphs (PSN or PSG, respectively), comprises a useful tool for detecting important residues for protein function, stability, folding and allostery. In RIN, the tertiary structure is represented by a network in which residues (nodes) are connected by interactions (edges). Such structural networks have consistently presented a few central residues that are important for shortening the pathways linking any two residues in a protein structure. To experimentally demonstrate that central residues effectively participate in protein properties, mutations were directed to seven central residues of the β-glucosidase Sfβgly (β-D-glucoside glucohydrolase; EC 3.2.1.21). These mutations reduced the thermal stability of the enzyme, as evaluated by changes in transition temperature (Tm ) and the denaturation rate at 45 °C. Moreover, mutations directed to the vicinity of a central residue also caused significant decreases in the Tm of Sfβgly and clearly increased the unfolding rate constant at 45 °C. However, mutations at noncentral residues or at surrounding residues did not affect the thermal stability of Sfβgly. Therefore, the data reported in the present study suggest that the perturbation of the central residues reduced the stability of the native structure of Sfβgly. These results are in agreement with previous findings showing that networks are robust, whereas attacks on central nodes cause network failure. Finally, the present study demonstrates that central residues underlie the functional properties of proteins.

  7. Detectability and medico-legal value of the gunshot residues in the intracorporeal channel.

    Science.gov (United States)

    Migliorini, Arnaldo Stanislao; Andreola, Salvatore; Battistini, Alessio; Gentile, Guendalina; Muccino, Enrico; Vancheri, Giulia; Zoja, Riccardo

    2015-11-01

    The application of the histochemical stain of sodium rhodizonate to the entrance wound for the detection of the lead (Pb) residues coming from the gunshot may be affected by false positive cases due to the contamination of the environmental Pb. The aim of the Authors is to histochemically search the Pb of GSR in a region which should be more protected by the contamination: the intracorporeal channel. Two hundreds and eighteen serial histological specimens of the intracorporeal channels coming from 25 subjects (dead due to gunshots and being autopsied at the Section of Legal Medicine of the Milan University, in the years 2013-2014) were stained with the sodium rhodizonate and sodium rhodizonate in acid environment (HCl 5%), and then observed by the microscope. The sodium rhodizonate showed a positivity for the Pb residues in the intracorporeal channel, with the detection of the particles within the first 2 cm beyond the entrance wound in 6 cases over the total number of 25 (24%). Victims were characterized by common features: short-barreled weapon; contact shots or short-distance shots; involvement of regions that were not covered by clothing; preservation of the microscopic structure of organs interested by the intracorporeal channel. The searching of GSR in the intracorporeal channel, even in conditions securing a high sensitivity, could represent an important test for the discrimination between an environmental contamination of Pb and the presence of Pb residues by GSR: once confirmed the presence of GSR in the intracorporeal channel by the histochemical analysis, the diagnostic process should require the application of the SEM-EDX for the confirmation of the results. Although not yet studied, this combination could be applied to cadavers exposed to the environment, with advanced post-mortal phenomena permitting at least the suspects of the existence of gunshot wounds at the macroscopic autopsy evaluation. Indeed, in some cases, the putrefaction is so advanced

  8. Possible roles of exceptionally conserved residues around the selectivity filters of sodium and calcium channels.

    Science.gov (United States)

    Tikhonov, Denis B; Zhorov, Boris S

    2011-01-28

    In the absence of x-ray structures of sodium and calcium channels their homology models are used to rationalize experimental data and design new experiments. A challenge is to model the outer-pore region that folds differently from potassium channels. Here we report a new model of the outer-pore region of the NaV1.4 channel, which suggests roles of highly conserved residues around the selectivity filter. The model takes from our previous study (Tikhonov, D. B., and Zhorov, B. S. (2005) Biophys. J. 88, 184-197) the general disposition of the P-helices, selectivity filter residues, and the outer carboxylates, but proposes new intra- and inter-domain contacts that support structural stability of the outer pore. Glycine residues downstream from the selectivity filter are proposed to participate in knob-into-hole contacts with the P-helices and S6s. These contacts explain the adapted tetrodotoxin resistance of snakes that feed on toxic prey through valine substitution of isoleucine in the P-helix of repeat IV. Polar residues five positions upstream from the selectivity filter residues form H-bonds with the ascending-limb backbones. Exceptionally conserved tryptophans are engaged in inter-repeat H-bonds to form a ring whose π-electrons would facilitate passage of ions from the outer carboxylates to the selectivity filter. The outer-pore model of CaV1.2 derived from the NaV1.4 model is also stabilized by the ring of exceptionally conservative tryptophans and H-bonds between the P-helices and ascending limbs. In this model, the exceptionally conserved aspartate downstream from the selectivity-filter glutamate in repeat II facilitates passage of calcium ions to the selectivity-filter ring through the tryptophan ring. Available experimental data are discussed in view of the models.

  9. Isovector coupling channel and central properties of the charge density distribution in heavy spherical nuclei

    Indian Academy of Sciences (India)

    S Haddad

    2010-09-01

    The influence of the isovector coupling channel on the central depression parameter and the central value of the charge density distribution in heavy spherical nuclei was studied. The isovector coupling channel leads to about 50% increase of the central depression parameter, and weakens the dependency of both central depression parameter and central density on the asymmetry, impressively contributing to the semibubble form of the charge density distribution in heavy nuclei, and increasing the probability of larger nuclei with higher proton numbers and higher neutron-to-proton ratios stable.

  10. Impact of river-tide dynamics on the residual water level slope and residual sediment transport in the Pearl River channel networks

    Science.gov (United States)

    Cai, Huayang; Zhang, Zihao; Yang, Qingshu; Ou, Suying

    2016-04-01

    Large-scale delta systems, such as the Rhine-Meuse delta, the Mississippi River delta, the Mekong delta, the Yangtze delta and the Pearl River delta etc., usually feature a typical channel networks, where individual channels are interrelated through a networks system, resulting in both longitudinal and transverse variations of residual water level slope (averaged over a lunar day) caused by the river-tide interplay. Enhancing our insight of river-tide dynamics in these channel networks has vital importance for the protection and management of estuarine environment since river-tide interplay is closely related to sediment transport, water quality, water utilization and estuarine ecosystem. In this study, we investigate the impact of river-tide dynamics on the temporal-spatial changes of flow and suspended sediment load in terms of residual water level slope and residual sediment transport in the Pearl River channel networks, which is one of the complex channel networks in the world. Making use of a nonstationary harmonic analysis (NS_TIDE), the continuous time series observations of velocity covering a spring-neap cycle in 1999 (representing flood season) and 2001 (representing dry season) collected from around 60 stations in the Pearl River channel networks have been used to extract the temporal-spatial changes in residual velocity and tidal properties (including amplitudes and phases) as a function of variable river flow debouching into the delta. On the basis of harmonic analysis, the tidally averaged friction is decomposed into contributions made by riverine forcing alone, river-tide interaction and tidal asymmetry using Chebyshev polynomials approach. It is shown that river flow enhances friction via river-tide interaction, which increases the residual water level slope that influences the distribution of suspended sediment load in the Pearl River channel networks.

  11. Use of residual redundancy in the design of joint source/channel coders

    Science.gov (United States)

    Sayood, Khalid; Borkenhagen, Jay C.

    1991-01-01

    A technique for providing error protection without the additional overhead required for channel coding is developed, starting from the premise that, during source coder design, for the sake of simplicity or due to imperfect knowledge, assumptions have to be made about the source which are often incorrect. This results in residual redundancy at the output of the source coder. The residual redundancy can then be used to provide error protection in much the same way as the insertion of redundancy in convolutional coding provides error protection. To show the validity of this approach, it is applied to image coding using differential pulse code modulation (DPCM). Substantial performance gains are obtained, in terms of both objective and subjective measures.

  12. Tyrosine Residues from the S4-S5 Linker of Kv11.1 Channels Are Critical for Slow Deactivation.

    Science.gov (United States)

    Ng, Chai-Ann; Gravel, Andrée E; Perry, Matthew D; Arnold, Alexandre A; Marcotte, Isabelle; Vandenberg, Jamie I

    2016-08-12

    Slow deactivation of Kv11.1 channels is critical for its function in the heart. The S4-S5 linker, which joins the voltage sensor and pore domains, plays a critical role in this slow deactivation gating. Here, we use NMR spectroscopy to identify the membrane-bound surface of the S4S5 linker, and we show that two highly conserved tyrosine residues within the KCNH subfamily of channels are membrane-associated. Site-directed mutagenesis and electrophysiological analysis indicates that Tyr-542 interacts with both the pore domain and voltage sensor residues to stabilize activated conformations of the channel, whereas Tyr-545 contributes to the slow kinetics of deactivation by primarily stabilizing the transition state between the activated and closed states. Thus, the two tyrosine residues in the Kv11.1 S4S5 linker play critical but distinct roles in the slow deactivation phenotype, which is a hallmark of Kv11.1 channels.

  13. Significance of the Centrally Expressed TRP Channel "Painless" in "Drosophila" Courtship Memory

    Science.gov (United States)

    Sakai, Takaomi; Sato, Shoma; Ishimoto, Hiroshi; Kitamoto, Toshihiro

    2013-01-01

    Considerable evidence has demonstrated that transient receptor potential (TRP) channels play vital roles in sensory neurons, mediating responses to various environmental stimuli. In contrast, relatively little is known about how TRP channels exert their effects in the central nervous system to control complex behaviors. This is also true for the…

  14. A conserved residue cluster that governs kinetics of ATP-dependent gating of Kir6.2 potassium channels

    DEFF Research Database (Denmark)

    Zhang, Roger S; Wright, Jordan; Pless, Stephan Alexander;

    2015-01-01

    that these residues play a role in lowering the transition state energy barrier between open and closed channel states. Using unnatural amino acid incorporation, we demonstrate the requirement for a planar amino acid at Kir6.2 position 68 for normal channel gating, potentially necessary to localize the ε-amine of Lys......ATP-sensitive potassium (KATP) channels are heteromultimeric complexes of an inwardly-rectifying Kir channel (Kir6.x) and sulfonylurea receptors (SUR). Their regulation by intracellular ATP and ADP generates electrical signals in response to changes in cellular metabolism. We investigated channel...... elements that control the kinetics of ATP-dependent regulation of KATP (Kir6.2 + SUR1) channels using rapid concentration jumps. WT Kir6.2 channels re-open after rapid washout of ATP with a time constant of approximately 60 ms. Extending similar kinetic measurements to numerous mutants revealed fairly...

  15. Wolf-Rayet Central Stars and the Binary Evolution Channel

    Directory of Open Access Journals (Sweden)

    Orsola De Marco

    2003-01-01

    Full Text Available Cálculos recientes de la evolución de estrellas sencillas han tenido éxito en reproducir la composicion de estrellas Wolf-Rayet (WR deficientes en hidrogeno que son además estrellas centrales de nebulosas planetarias. Sin embargo, las observaciones infrarrojas mas recientes dejan claro que el esquema de estrellas sencillas no concuerda con las propiedades del polvo que rodea a muchas estrellas centrales tipo WR. Por otro lado, la binariedad podría explicar las observaciones en el infrarrojo asi como ofrecer una posibilidad de remover la envoltura rica en H de la estrella. En este trabajo proponemos dos esquemas con estrellas binarias originalmente propuestos por De Marco & Soker en relación a las estrellas centrales tipo WR. En el primero, un sistema binario cercano da como resultado el regreso de material eyectado a la estrella y eventualmente una estrella central deficiente en H. Este esquema se invoca para explicar la estrella central CPD-56º8032 en [WC10] y su disco de polvo. El segundo esquema propone que la mayoría de las estrellas centrales tipo WR son resultado de una fusión con una compañera de baja masa durante la fase AGB. Modelamos este esquema por medio de simulaciones hidrodinámicas en 3D, que simulan la fase de envolvente común entre una estrella AGB y una compañera de entre 0.1 and 0.2-M๏ durante el primer y décimo pulso térmico.

  16. Mapping of dihydropyridine binding residues in a less sensitive invertebrate L-type calcium channel (LCa v 1).

    Science.gov (United States)

    Senatore, Adriano; Boone, Adrienne; Lam, Stanley; Dawson, Taylor F; Zhorov, Boris; Spafford, J David

    2011-01-01

    Invertebrate L-type calcium channel, LCa(v) 1, isolated from the pond snail Lymnaea stagnalis is nearly indistinguishable from mammalian Ca(v) 1.2 (α1C) calcium channel in biophysical characteristics observed in vitro. These L-type channels are likely constrained within a narrow range of biophysical parameters to perform similar functions in the snail and mammalian cardiovascular systems. What distinguishes snail and mammalian L-type channels is a difference in dihydropyridine sensitivity: 100 nM isradipine exhibits a significant block of mammalian Ca(v) 1.2 currents without effect on snail LCa(v)1 currents. The native snail channel serves as a valuable surrogate for validating key residue differences identified from previous experimental and molecular modeling work. As predicted, three residue changes in LCa(v)1 (N_3o18, F_3i10, and I_4i12) replaced with DHP-sensing residues in respective positions of Ca(v) 1.2, (Q_3o18, Y_3i10, and M_4i12) raises the potency of isradipine block of LCa(v)1 channels to that of mammalian Ca(v) 1.2. Interestingly, the single N_3o18_Q mutation in LCa(v) 1 channels lowers DHP sensitivity even further and the triple mutation bearing enhanced isradipine sensitivity, still retains a reduced potency of agonist, (S)-Bay K8644.

  17. Improper Gaussian signaling in full-duplex relay channels with residual self-interference

    KAUST Repository

    Gaafar, Mohamed

    2016-07-26

    We study the potential employment of improper Gaussian signaling (IGS) in full-duplex cooperative settings with residual self-interference (RSI). IGS is recently shown to outperform traditional proper Gaussian signaling (PGS) in several interference-limited channel settings. In this work, IGS is employed in an attempt to alleviate the RSI adverse effect in full-duplex relaying (FDR). To this end, we derive a tight upper bound expression for the end-to-end outage probability in terms of the relay signal parameters represented in its power and circularity coefficient. We further show that the derived upper bound is either monotonic or unimodal in the relay\\'s circularity coefficient. This result allows for easily locating the global optimal point using known numerical methods. Based on the analysis, IGS allows FDR systems to operate even with high RSI. It is shown that, while the communication totally fails with PGS as the RSI increases, the IGS outage probability approaches a fixed value that depends on the channel statistics and target rate. The obtained results show that IGS can leverage higher relay power budgets than PGS to improve the performance, meanwhile it relieves its RSI impact via tuning the signal impropriety. © 2016 IEEE.

  18. Differential role of the menthol-binding residue Y745 in the antagonism of thermally gated TRPM8 channels

    Directory of Open Access Journals (Sweden)

    Ferrer-Montiel Antonio

    2009-11-01

    Full Text Available Abstract Background TRPM8 is a non-selective cation channel that belongs to the melastatin subfamily of the transient receptor potential (TRP ion channels. TRPM8 is activated by voltage, cold and cooling compounds such as menthol. Despite its essential role for cold temperature sensing in mammals, the pharmacology of TRPM8 is still in its infancy. Recently, tyrosine 745 (Y745 was identified as a critical residue for menthol sensitivity of the channel. In this report, we study the effect of mutating this residue on the action of several known TRPM8 antagonists: BCTC, capsazepine, SKF96365, and clotrimazole as well as two new inhibitor candidates, econazole and imidazole. Results We show that Y745 at the menthol binding site is critical for inhibition mediated by SKF96365 of cold- and voltage-activated TRPM8 currents. In contrast, the inhibition by other antagonists was unaffected by the mutation (BCTC or only partially reduced (capsazepine, clotrimazole, econazole, suggesting that additional binding sites exist on the TRPM8 channel from where the inhibitors exert their negative modulation. Indeed, a molecular docking model implies that menthol and SKF96365 interact readily with Y745, while BCTC is unable to bind to this residue. Conclusion In summary, we identify structural elements on the TRPM8 channel that are critical for the action of channel antagonists, providing valuable information for the future design of new, specific modulator compounds.

  19. AQP4 plasma membrane trafficking or channel gating is not significantly modulated by phosphorylation at COOH-terminal serine residues

    DEFF Research Database (Denmark)

    Assentoft, Mette; Larsen, Brian R; Olesen, Emma T B;

    2014-01-01

    . Phosphorylation of aquaporins can regulate plasma membrane localization and, possibly, the unit water permeability via gating of the AQP channel itself. In vivo phosphorylation of six serine residues in the COOH terminus of AQP4 has been detected by mass spectrometry: Ser(276), Ser(285), Ser(315), Ser(316), Ser...... heterologous expression in Xenopus laevis oocytes (along with serine-to-aspartate mutants of the same residues to mimic a phosphorylation). None of the mutant AQP4 constructs displayed alterations in the unit water permeability. Thus phosphorylation of six different serine residues in the COOH terminus of AQP4...

  20. Aspartic Acid Residue D3 Critically Determines Cx50 Gap Junction Channel Transjunctional Voltage-Dependent Gating and Unitary Conductance

    Science.gov (United States)

    Xin, Li; Nakagawa, So; Tsukihara, Tomitake; Bai, Donglin

    2012-01-01

    Previous studies have suggested that the aspartic acid residue (D) at the third position is critical in determining the voltage polarity of fast Vj-gating of Cx50 channels. To test whether another negatively charged residue (a glutamic acid residue, E) could fulfill the role of the D3 residue, we generated the mutant Cx50D3E. Vj-dependent gating properties of this mutant channel were characterized by double-patch-clamp recordings in N2A cells. Macroscopically, the D3E substitution reduced the residual conductance (Gmin) to near zero and outwardly shifted the half-inactivation voltage (V0), which is a result of both a reduced aggregate gating charge (z) and a reduced free-energy difference between the open and closed states. Single Cx50D3E gap junction channels showed reduced unitary conductance (γj) of the main open state, reduced open dwell time at ±40 mV, and absence of a long-lived substate. In contrast, a G8E substitution tested to compare the effects of the E residue at the third and eighth positions did not modify the Vj-dependent gating profile or γj. In summary, this study is the first that we know of to suggest that the D3 residue plays an essential role, in addition to serving as a negative-charge provider, as a critical determinant of the Vj-dependent gating sensitivity, open-closed stability, and unitary conductance of Cx50 gap junction channels. PMID:22404924

  1. Cavity residue leucine 95 and channel residues glutamine 204, aspartic acid 211, and phenylalanine 269 of toluene o-xylene monooxygenase influence catalysis.

    Science.gov (United States)

    Kurt, Cansu; Sönmez, Burcu; Vardar, Nurcan; Yanık-Yıldırım, K Cansu; Vardar-Schara, Gönül

    2016-09-01

    Structural analysis of toluene-o-xylene monooxygenase (ToMO) hydroxylase revealed the presence of three hydrophobic cavities, a channel, and a pore leading from the protein surface to the active site. Here, saturation mutagenesis was used to investigate the catalytic roles of alpha-subunit (TouA) second cavity residue L95 and TouA channel residues Q204, D211, and F269. By testing the substrates toluene, phenol, nitrobenzene, and/or naphthalene, these positions were found to influence the catalytic activity of ToMO. Several regiospecific variants were identified from TouA positions Q204, F269, and L95. For example, TouA variant Q204H had the regiospecificity of nitrobenzene changed significantly from 30 to 61 % p-nitrophenol. Interestingly, a combination of mutations at Q204H and A106V altered the regiospecificity of nitrobenzene back to 27 % p-nitrophenol. TouA variants F269Y, F269P, Q204E, and L95D improved the meta-hydroxylating capability of nitrobenzene by producing 87, 85, 82, and 77 % m-nitrophenol, respectively. For naphthalene oxidation, TouA variants F269V, Q204A, Q204S/S222N, and F269T had the regiospecificity changed from 16 to 9, 10, 23, and 25 % 2-naphthol, respectively. Here, two additional TouA residues, S222 and A106, were also identified that may have important roles in catalysis. Most of the isolated variants from D211 remained active, whereas having a hydrophobic residue at this position appeared to diminish the catalytic activity toward naphthalene. The mutational effects on the ToMO regiospecificity described here suggest that it is possible to further fine tune and engineer the reactivity of multicomponent diiron monooxygenases toward different substrates at positions that are relatively distant from the active site.

  2. [Acceptability of indoor residual spraying in the Central-Western of Senegal].

    Science.gov (United States)

    Sy, O; Cisse, B; Tairou, F; Diallo, A; Ba, E; Gomis, J F; NDiaye, J L; Konaté, L; Gaye, O; Milligan, P; Faye, O

    2015-08-01

    The recent decline of malaria transmission in central-western of Senegal after a scaling up of control measures gives an open window for interventions toward malaria elimination. As a consequence, malaria transmission is now occurring as hotspots. The aim of the project is to evaluate whether target control measures combining indoor residual spraying (IRS) with chemoprophylaxis can virtually eliminate malaria in hotspots. Targeted villages located in four (4) health districts (Mbour, Fatick, Niakhar and Bambey) were sprayed in august 2013 with Actellic® 300 CS (Pirimiphosmethyl). Our objective in this study is to evaluate the acceptability of IRS in the population. IRS is a very complex intervention that requires strong adhesion of populations. After its implementation, 370 households have been interviewed. The results of this survey showed good acceptability of IRS using Actellic® 300 CS, with 97.8% of beneficiaries who declared that IRS is good and even excellent for the community. Despite inconveniences that may arise during intervention, including the preparation of structures to be treated, 98% of respondents were not disturbed in their daily activities. 98.6% of responders declared that sprayers were working with professionalism and almost all households (99.7%) are willing to accept IRS next year. The survey revealed a good acceptability of indoor residual spraying in hot spots located in central-western of Senegal; spraying with Actellic® 300 CS did not cause a problem to the targeted populations. Finally, there is great satisfaction in the population due a huge reduction of mosquito nuisances.

  3. Large teleseismic P-wave residuals observed at the Alban Hills volcano, Central Italy

    Directory of Open Access Journals (Sweden)

    H. Mahadeva Iyer

    1994-06-01

    Full Text Available We collected teleseismic waveforms from a digital microseismic network deployed by the Istituto Nazionale di Geofisica (ING in collaboration with the U.S. Geological Survey (USGS, on the Alban Hills Quaternary volcano during the 1989-1990 seismic swann. About 50 events were recorded by the network, 30 of them by at least 4 stations. We analysed the data in order to image crustal heterogeneities beneath the volcano. The results show large delay time residuals up to - 1 second for stations located on the volcano with respect to station CP9 of the National Seismic Network located about 20 km to the east, on the Apennines. This suggests that the whole area overlies a broad low-velocity region. Although the ray coverage is not very dense, we model the gross seismic structure beneath the volcano by inverting the teleseismic relative residuals with the ACH technique. The main features detected by tbc inversion are a low-velocity zone beneath the southwestern fiank of tbc volcano, and a high-velocity region beneath the center. The depth extension of these anomalous zones ranges between 5 and 16 km. The correspondence between the low-velocity region and the most recent activity of the volcano (- 0.027 Ma leads us to infer the presence of a still hot magmatic body in the crust beneath the southwestern side of the volcano, whereas the central part overlies the older and colder high-velocity volcanic roots related to the previous central activity (0.7 to 0.3 Ma.

  4. Dune convergence/divergence controlled by residual current vortices in the Jade tidal channel, south-eastern North Sea

    Science.gov (United States)

    Kubicki, Adam; Kösters, Frank; Bartholomä, Alexander

    2017-02-01

    A field of large to very large subaqueous dunes was investigated in the Jade tidal channel, south-eastern North Sea, between January 2006 and October 2011. A ground-truthed sidescan sonar sediment map shows that the dunes, which are located on top of a consolidated clay surface, are composed of medium to coarse sand. A series of 35 consecutive high-resolution bathymetric surfaces collected by multibeam echosounder revealed a complex migration pattern induced by the reversing tidal currents. Various parts of the dune field are under the influence of either ebb- or flood-dominated currents, as indicated by dune asymmetries. Although some dunes migrate at a pace exceeding 100 m/year, the majority are displaced by 30 m/year in the direction of the locally dominant current. In the deepest part of the channel, however, dunes were observed to converge head-on, resulting in practically zero net transport with minor oscillations of symmetrical dunes at the apex. Applying the numerical UnTRIM model for the simulation of the fair-weather hydrology, a simplified map of residual current vectors over the dune field was generated. The residual flow vectors are found to perfectly match the derived dune migration vectors, suggesting that dune convergence is controlled by two counter-rotating residual current vortices caused by the local shape of the tidal channel. As no sediment build-up is observed, a mechanism of sediment bypassing with potential recirculation must exist, but has not yet been identified.

  5. The K+ channel opener 1-EBIO potentiates residual function of mutant CFTR in rectal biopsies from cystic fibrosis patients.

    Directory of Open Access Journals (Sweden)

    Eva K Roth

    Full Text Available BACKGROUND: The identification of strategies to improve mutant CFTR function remains a key priority in the development of new treatments for cystic fibrosis (CF. Previous studies demonstrated that the K⁺ channel opener 1-ethyl-2-benzimidazolone (1-EBIO potentiates CFTR-mediated Cl⁻ secretion in cultured cells and mouse colon. However, the effects of 1-EBIO on wild-type and mutant CFTR function in native human colonic tissues remain unknown. METHODS: We studied the effects of 1-EBIO on CFTR-mediated Cl⁻ secretion in rectal biopsies from 47 CF patients carrying a wide spectrum of CFTR mutations and 57 age-matched controls. Rectal tissues were mounted in perfused micro-Ussing chambers and the effects of 1-EBIO were compared in control tissues, CF tissues expressing residual CFTR function and CF tissues with no detectable Cl⁻ secretion. RESULTS: Studies in control tissues demonstrate that 1-EBIO activated CFTR-mediated Cl⁻ secretion in the absence of cAMP-mediated stimulation and potentiated cAMP-induced Cl⁻ secretion by 39.2±6.7% (P<0.001 via activation of basolateral Ca²⁺-activated and clotrimazole-sensitive KCNN4 K⁺ channels. In CF specimens, 1-EBIO potentiated cAMP-induced Cl⁻ secretion in tissues with residual CFTR function by 44.4±11.5% (P<0.001, but had no effect on tissues lacking CFTR-mediated Cl⁻ conductance. CONCLUSIONS: We conclude that 1-EBIO potentiates Cl⁻secretion in native CF tissues expressing CFTR mutants with residual Cl⁻ channel function by activation of basolateral KCNN4 K⁺ channels that increase the driving force for luminal Cl⁻ exit. This mechanism may augment effects of CFTR correctors and potentiators that increase the number and/or activity of mutant CFTR channels at the cell surface and suggests KCNN4 as a therapeutic target for CF.

  6. Down regulation of sodium channels in the central nervous system of hibernating snails.

    Science.gov (United States)

    Kiss, T; Battonyai, I; Pirger, Z

    2014-05-28

    Hibernation, as behavior, is an evolutionary mode of adaptation of animal species to unfavorable environmental conditions. It is generally characterized by suppressed metabolism, which also includes down regulation of the energy consuming ion-channel functioning. Experimental data regarding decreased ion-channel function are scarce. Therefore, our goal was to study the possible down regulation of voltage-gated sodium channel (NaV) subtypes in the neurons of hibernating snails. Our immunohistochemical experiments revealed that the expression of NaV1.8-like channels in the central nervous system was substantially down regulated in hibernating animals. In contrast to NaV1.8-like, the NaV1.9-like channels were present in neurons independently from hibernating and non-hibernating states. Our western blot data supported the immunohistochemical results according to which the band of the NaV1.8-like channel protein was less intensively labeled in the homogenate of the hibernating snails. The NaV1.9-like immunoreactivity was equally present both in hibernating and active snails. Micro-electrophysiological experiments show that in hibernating snails both NaV1.8- and NaV1.9-like currents are substantially decreased compared to that of the active snails. The contradictory electrophysiological and immunohistochemical or western blot data suggest that the molecular mechanisms of the "channel arrest" could be different in diverse NaV channel subtypes. Climate changes will affect temperature extremes and a question is how different species beyond their physiological tolerance will or able to adapt to changing environment. Hibernation is an important mode of adaptation to extreme climatic variations, and pursuant to this the present results may contribute to the study of the behavioral ecology.

  7. Chimeras Reveal a Single Lipid-Interface Residue that Controls MscL Channel Kinetics as well as Mechanosensitivity

    Directory of Open Access Journals (Sweden)

    Li-Min Yang

    2013-02-01

    Full Text Available MscL, the highly conserved bacterial mechanosensitive channel of large conductance, serves as an osmotic “emergency release valve,” is among the best-studied mechanosensors, and is a paradigm of how a channel senses and responds to membrane tension. Although all homologs tested thus far encode channel activity, many show functional differences. We tested Escherichia coli and Staphylococcus aureus chimeras and found that the periplasmic region of the protein, particularly E. coli I49 and the equivalent S. aureus F47 at the periplasmic lipid-aqueous interface of the first transmembrane domain, drastically influences both the open dwell time and the threshold of channel opening. One mutant shows a severe hysteresis, confirming the importance of this residue in determining the energy barriers for channel gating. We propose that this site acts similarly to a spring for a clasp knife, adjusting the resistance for obtaining and stabilizing an open or closed channel structure.

  8. Contribution of a lysine residue in the first transmembrane segment to the selectivity filter region in the CFTR chloride channel.

    Science.gov (United States)

    Negoda, Alexander; El Hiani, Yassine; Cowley, Elizabeth A; Linsdell, Paul

    2017-02-21

    The anion selectivity and conductance of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel are determined predominantly by interactions between permeant anions and the narrow region of the channel pore. This narrow region has therefore been described as functioning as the "selectivity filter" of the channel. Multiple pore-lining transmembrane segments (TMs) have previously been shown to contribute to the selectivity filter region. However, little is known about the three-dimensional organization of this region, or how multiple TMs combine to determine its functional properties. In the present study we have used patch clamp recording to identify changes in channel function associated with the formation of disulfide cross-links between cysteine residues introduced into different TMs within the selectivity filter. Cysteine introduced at position L102 in TM1 was able to form disulfide bonds with F337C and T338C in TM6, two positions that are known to play key roles in determining anion permeation properties. Consistent with this proximal arrangement of L102, F337 and T338, different mutations at L102 altered anion selectivity and conductance properties in a way that suggests that this residue plays an important role in determining selectivity filter function, albeit a much lesser role than that of F337. These results suggest an asymmetric three-dimensional arrangement of the key selectivity filter region of the pore, as well as having important implications regarding the molecular mechanism of anion permeation.

  9. Phosphorylation of K[superscript +] Channels at Single Residues Regulates Memory Formation

    Science.gov (United States)

    Vernon, Jeffrey; Irvine, Elaine E.; Peters, Marco; Jeyabalan, Jeshmi; Giese, K. Peter

    2016-01-01

    Phosphorylation is a ubiquitous post-translational modification of proteins, and a known physiological regulator of K[superscript +] channel function. Phosphorylation of K[superscript +] channels by kinases has long been presumed to regulate neuronal processing and behavior. Although circumstantial evidence has accumulated from behavioral studies…

  10. Pyrethroids differentially alter voltage-gated sodium channels from the honeybee central olfactory neurons.

    Directory of Open Access Journals (Sweden)

    Aklesso Kadala

    Full Text Available The sensitivity of neurons from the honey bee olfactory system to pyrethroid insecticides was studied using the patch-clamp technique on central 'antennal lobe neurons' (ALNs in cell culture. In these neurons, the voltage-dependent sodium currents are characterized by negative potential for activation, fast kinetics of activation and inactivation, and the presence of cumulative inactivation during train of depolarizations. Perfusion of pyrethroids on these ALN neurons submitted to repetitive stimulations induced (1 an acceleration of cumulative inactivation, and (2 a marked slowing of the tail current recorded upon repolarization. Cypermethrin and permethrin accelerated cumulative inactivation of the sodium current peak in a similar manner and tetramethrin was even more effective. The slow-down of channel deactivation was markedly dependent on the type of pyrethroid. With cypermethrin, a progressive increase of the tail current amplitude along with successive stimulations reveals a traditionally described use-dependent recruitment of modified sodium channels. However, an unexpected decrease in this tail current was revealed with tetramethrin. If one considers the calculated percentage of modified channels as an index of pyrethroids effects, ALNs are significantly more susceptible to tetramethrin than to permethrin or cypermethrin for a single depolarization, but this difference attenuates with repetitive activity. Further comparison with peripheral neurons from antennae suggest that these modifications are neuron type specific. Modeling the sodium channel as a multi-state channel with fast and slow inactivation allows to underline the effects of pyrethroids on a set of rate constants connecting open and inactivated conformations, and give some insights to their specificity. Altogether, our results revealed a differential sensitivity of central olfactory neurons to pyrethroids that emphasize the ability for these compounds to impair detection and

  11. Prediction of Velocity-Dip-Position at the Central Section of Open Channels using Entropy Theory

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    Snehasis Kundu

    2017-01-01

    Full Text Available An analytical model to predict the velocity-dip-position at the central section of open channels is presented in this study. Unlike the previous studies where empirical or semi-empirical models were suggested, in this study the model is derived by using entropy theory. Using the principle of maximum entropy, the model for dip-position is derived by maximizing the Shannon entropy function after assuming dimensionless dip-position at the central section as a random variable. No estimation of empirical parameter is required for calculating dip-position from the proposed model. The model is able to predict the location of maximum velocity at the central section of an open channel with any aspect ratio. The developed model of velocity-dip-position is tested with experimental data from twenty-two researchers reported in literature for a wide range of aspect ratio. The model is also compared with other existing empirical models. The present model shows good agreement with the observed data and provides least prediction error compared to other models.

  12. AQP4 plasma membrane trafficking or channel gating is not significantly modulated by phosphorylation at COOH-terminal serine residues.

    Science.gov (United States)

    Assentoft, Mette; Larsen, Brian R; Olesen, Emma T B; Fenton, Robert A; MacAulay, Nanna

    2014-11-15

    Aquaporin 4 (AQP4) is the predominant water channel in the mammalian brain and is mainly expressed in the perivascular glial endfeet at the brain-blood interface. AQP4 serves as a water entry site during brain edema formation, and regulation of AQP4 may therefore be of therapeutic interest. Phosphorylation of aquaporins can regulate plasma membrane localization and, possibly, the unit water permeability via gating of the AQP channel itself. In vivo phosphorylation of six serine residues in the COOH terminus of AQP4 has been detected by mass spectrometry: Ser(276), Ser(285), Ser(315), Ser(316), Ser(321), and Ser(322). To address the role of these phosphorylation sites for AQP4 function, serine-to-alanine mutants were created to abolish the phosphorylation sites. All mutants were detected at the plasma membrane of transfected C6 cells, with the fraction of the total cellular AQP4 expressed at the plasma membrane of transfected C6 cells being similar between the wild-type (WT) and mutant forms of AQP4. Activation of protein kinases A, C, and G in primary astrocytic cultures did not affect the plasma membrane abundance of AQP4. The unit water permeability was determined for the mutant AQP4s upon heterologous expression in Xenopus laevis oocytes (along with serine-to-aspartate mutants of the same residues to mimic a phosphorylation). None of the mutant AQP4 constructs displayed alterations in the unit water permeability. Thus phosphorylation of six different serine residues in the COOH terminus of AQP4 appears not to be required for proper plasma membrane localization of AQP4 or to act as a molecular switch to gate the water channel.

  13. Entrance channel effects on the evaporation residue yields in reactions leading to the $^{220}$Th compound nucleus

    CERN Document Server

    Kim, Kyungil; Mandaglio, Giuseppe; Giardina, Giorgio; Kim, Youngman

    2014-01-01

    The evaporation residue yields from compound nuclei $^{220}$Th formed in the $^{16}$O+$^{204}$Pb, $^{40}$Ar+$^{180}$Hf, $^{82}$Se+$^{138}$Ba, $^{124}$Sn+$^{96}$Zr reactions are analyzed to study the entrance channel effects by comparison of the capture, fusion and evaporation residue cross sections calculated by the combined dinuclear system (DNS) and advanced statistical models. The difference between evaporation residue (ER) cross sections can be related to the stages of compound nucleus formation or/and at its surviving against fission. The sensitivity of the both stages in the evolution of DNS up to the evaporation residue formation to the angular momentum of DNS is studied. The difference between fusion excitation functions are explained by the hindrance to complete fusion due to the larger intrinsic fusion barrier $B^*_{\\rm fus}$ for the transformation of the DNS into a compound nucleus and the increase of the quasifission contribution due to the decreasing of quasifission barrier $B_{\\rm qf}$ as a func...

  14. Substitutions at the opening of the Rubisco central solvent channel affect holoenzyme stability and CO2/O 2 specificity but not activation by Rubisco activase.

    Science.gov (United States)

    Esquivel, M Gloria; Genkov, Todor; Nogueira, Ana S; Salvucci, Michael E; Spreitzer, Robert J

    2013-12-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the initial step of carbon metabolism in photosynthesis. The holoenzyme comprises eight large subunits, arranged as a tetramer of dimers around a central solvent channel that defines a fourfold axis of symmetry, and eight small subunits, arranged as two tetramers at the poles of the axis. The phylogenetically divergent small-subunit loops between β-strands A and B form the entrance to the solvent channel. In the green alga Chlamydomonas reinhardtii, Ile-58 from each of the four small-subunit βA-βB loops defines the minimal diameter of the channel opening. To understand the role of the central solvent channel in Rubisco function, directed mutagenesis and transformation of Chlamydomonas were employed to replace Ile-58 with Ala, Lys, Glu, Trp, or three Trp residues (I58W3) to close the entrance to the channel. The I58E, I58K, and I58W substitutions caused only small decreases in photosynthetic growth at 25 and 35 °C, whereas I58W3 had a substantial effect at both temperatures. The mutant enzymes had decreased carboxylation rates, but the I58W3 enzyme had decreases in both carboxylation and CO2/O2 specificity. The I58E, I58W, and I58W3 enzymes were inactivated at lower temperatures than wild-type Rubisco, and were degraded at slower rates under oxidative stress. However, these mutant enzymes were activated by Rubisco activase at normal rates, indicating that the structural transition required for carboxylation is not affected by altering the solvent channel opening. Structural dynamics alone may not be responsible for these distant effects on the Rubisco active site.

  15. Continuum electrostatic calculations of the pKa of ionizable residues in an ion channel: dynamic vs. static input structure.

    Science.gov (United States)

    Aguilella-Arzo, M; Aguilella, V M

    2010-04-01

    We have computed the pK(a)'s of the ionizable residues of a protein ion channel, the Staphylococcus aureus toxin alpha-hemolysin, by using two types of input structures, namely the crystal structure of the heptameric alpha-hemolysin and a set of over four hundred snapshots from a 4.38 ns Molecular Dynamics simulation of the protein inserted in a phospholipid planar bilayer. The comparison of the dynamic picture provided by the Molecular Simulation with the static one based on the X-ray crystal structure of the protein embedded in a lipid membrane allows analyzing the influence of the fluctuations in the protein structure on its ionization properties. We find that the use of the dynamic structure provides interesting information about the sensitivity of the computed pK(a) of a given residue to small changes in the local structure. The calculated pK(a) are consistent with previous indirect estimations obtained from single-channel conductance and selectivity measurements.

  16. A central-upwind scheme with artificial viscosity for shallow-water flows in channels

    Science.gov (United States)

    Hernandez-Duenas, Gerardo; Beljadid, Abdelaziz

    2016-10-01

    We develop a new high-resolution, non-oscillatory semi-discrete central-upwind scheme with artificial viscosity for shallow-water flows in channels with arbitrary geometry and variable topography. The artificial viscosity, proposed as an alternative to nonlinear limiters, allows us to use high-resolution reconstructions at a low computational cost. The scheme recognizes steady states at rest when a delicate balance between the source terms and flux gradients occurs. This balance in irregular geometries is more complex than that taking place in channels with vertical walls. A suitable technique is applied by properly taking into account the effects induced by the geometry. Incorporating the contributions of the artificial viscosity and an appropriate time step restriction, the scheme preserves the positivity of the water's depth. A description of the proposed scheme, its main properties as well as the proofs of well-balance and the positivity of the scheme are provided. Our numerical experiments confirm stability, well-balance, positivity-preserving properties and high resolution of the proposed method. Comparisons of numerical solutions obtained with the proposed scheme and experimental data are conducted, showing a good agreement. This scheme can be applied to shallow-water flows in channels with complex geometry and variable bed topography.

  17. Simulation of residual oil displacement in a sinusoidal channel with the lattice Boltzmann method

    CERN Document Server

    Otomo, Hiroshi; Hazlett, Randy; Li, Yong; Staroselsky, Ilya; Zhang, Raoyang; Chen, Hudong

    2016-01-01

    We simulate oil slug displacement in a sinusoidal channel in order to validate computational models and algorithms for multi-component flow. This case fits in the gap between fully realistic cases characterized by complicated geometry and academic cases with simplistic geometry. Our computational model is based on the lattice Boltzmann method and allows for variation of physical parameters such as wettability and viscosity. The effect of variation of model parameters is analyzed, in particular via comparison with analytical solutions. We discuss the requirements for accurate solution of the oil slug displacement problem.

  18. Acid-Sensing Ion Channels as Potential Pharmacological Targets in Peripheral and Central Nervous System Diseases.

    Science.gov (United States)

    Radu, Beatrice Mihaela; Banciu, Adela; Banciu, Daniel Dumitru; Radu, Mihai

    2016-01-01

    Acid-sensing ion channels (ASICs) are widely expressed in the body and represent good sensors for detecting protons. The pH drop in the nervous system is equivalent to ischemia and acidosis, and ASICs are very good detectors in discriminating slight changes in acidity. ASICs are important pharmacological targets being involved in a variety of pathophysiological processes affecting both the peripheral nervous system (e.g., peripheral pain, diabetic neuropathy) and the central nervous system (e.g., stroke, epilepsy, migraine, anxiety, fear, depression, neurodegenerative diseases, etc.). This review discusses the role played by ASICs in different pathologies and the pharmacological agents acting on ASICs that might represent promising drugs. As the majority of above-mentioned pathologies involve not only neuronal dysfunctions but also microvascular alterations, in the next future, ASICs may be also considered as potential pharmacological targets at the vasculature level. Perspectives and limitations in the use of ASICs antagonists and modulators as pharmaceutical agents are also discussed.

  19. A genetic screen for dihydropyridine (DHP-resistant worms reveals new residues required for DHP-blockage of mammalian calcium channels.

    Directory of Open Access Journals (Sweden)

    Trevor C Y Kwok

    2008-05-01

    Full Text Available Dihydropyridines (DHPs are L-type calcium channel (Ca(v1 blockers prescribed to treat several diseases including hypertension. Ca(v1 channels normally exist in three states: a resting closed state, an open state that is triggered by membrane depolarization, followed by a non-conducting inactivated state that is triggered by the influx of calcium ions, and a rapid change in voltage. DHP binding is thought to alter the conformation of the channel, possibly by engaging a mechanism similar to voltage dependent inactivation, and locking a calcium ion in the pore, thereby blocking channel conductance. As a Ca(v1 channel crystal structure is lacking, the current model of DHP action has largely been achieved by investigating the role of candidate Ca(v1 residues in mediating DHP-sensitivity. To better understand DHP-block and identify additional Ca(v1 residues important for DHP-sensitivity, we screened 440,000 randomly mutated Caenorhabditis elegans genomes for worms resistant to DHP-induced growth defects. We identified 30 missense mutations in the worm Ca(v1 pore-forming (alpha(1 subunit, including eleven in conserved residues known to be necessary for DHP-binding. The remaining polymorphisms are in eight conserved residues not previously associated with DHP-sensitivity. Intriguingly, all of the worm mutants that we analyzed phenotypically exhibited increased channel activity. We also created orthologous mutations in the rat alpha(1C subunit and examined the DHP-block of current through the mutant channels in culture. Six of the seven mutant channels examined either decreased the DHP-sensitivity of the channel and/or exhibited significant residual current at DHP concentrations sufficient to block wild-type channels. Our results further support the idea that DHP-block is intimately associated with voltage dependent inactivation and underscores the utility of C. elegans as a screening tool to identify residues important for DHP interaction with mammalian

  20. The lending channel and budget balance: empirical evidences from Central and Eastern European economies

    Directory of Open Access Journals (Sweden)

    Bogdan-Gabriel MOINESCU

    2013-03-01

    Full Text Available The study aims to deepen the analysis on the indirect dependence of government budget balance on private sector credit flow in the countries of Central and Eastern Europe. The added value of this approach consists of two elements. First, the analysis suggests developing the traditional analytical framework of assessing risks to public finance stability by including second round effects of negative fiscal impulses on credit to private sector during recession periods. Second, the study provides empirical evidence on the importance of economic growth transmission channel for the impact of credit accelerator effects on primary deficit. At the same time, nonperforming loans channel proved to be insignificant, especially in relation to the persistency of last year’s budget deficit and the effects of budget allocations pro-cyclicality. However, loan portfolio quality seems to be more relevant in the case of public debt service, through its influence on the evolution of the yield on long-term government securities that is closely related to sovereign risk premium. Nevertheless, strengthening the financial safety net by the introduction of resolution funds will most probably break the link investors saw between credit portfolio quality and the impending increase in budget spending. This expected development across not only CEE countries, but at the EU level also, will facilitate the isolation of sovereign risk premium from non-performing loans’ dynamics.

  1. Mitigation of hazards from future lahars from Mount Merapi in the Krasak River channel near Yogyakarta, central Java

    Science.gov (United States)

    Ege, John R.; ,

    1983-01-01

    Procedures for reducing hazards from future lahars and debris flows in the Krasak River channel near Yogyakarta, Central Java, Indonesia, include (1) determining the history of the location, size, and effects of previous lahars and debris flows, and (2) decreasing flow velocities. The first may be accomplished by geologic field mapping along with acquiring information by interviewing local residents, and the second by increasing the cross sectional area of the river channel and constructing barriers in the flow path.

  2. Conserved residues within the putative S4-S5 region serve distinct functions among thermosensitive vanilloid transient receptor potential (TRPV) channels.

    Science.gov (United States)

    Boukalova, Stepana; Marsakova, Lenka; Teisinger, Jan; Vlachova, Viktorie

    2010-12-31

    The vanilloid transient receptor potential channel TRPV1 is a tetrameric six-transmembrane segment (S1-S6) channel that can be synergistically activated by various proalgesic agents such as capsaicin, protons, heat, or highly depolarizing voltages, and also by 2-aminoethoxydiphenyl borate (2-APB), a common activator of the related thermally gated vanilloid TRP channels TRPV1, TRPV2, and TRPV3. In these channels, the conserved charged residues in the intracellular S4-S5 region have been proposed to constitute part of a voltage sensor that acts in concert with other stimuli to regulate channel activation. The molecular basis of this gating event is poorly understood. We mutated charged residues all along the S4 and the S4-S5 linker of TRPV1 and identified four potential voltage-sensing residues (Arg(557), Glu(570), Asp(576), and Arg(579)) that, when specifically mutated, altered the functionality of the channel with respect to voltage, capsaicin, heat, 2-APB, and/or their interactions in different ways. The nonfunctional charge-reversing mutations R557E and R579E were partially rescued by the charge-swapping mutations R557E/E570R and D576R/R579E, indicating that electrostatic interactions contribute to allosteric coupling between the voltage-, temperature- and capsaicin-dependent activation mechanisms. The mutant K571E was normal in all aspects of TRPV1 activation except for 2-APB, revealing the specific role of Lys(571) in chemical sensitivity. Surprisingly, substitutions at homologous residues in TRPV2 or TRPV3 had no effect on temperature- and 2-APB-induced activity. Thus, the charged residues in S4 and the S4-S5 linker contribute to voltage sensing in TRPV1 and, despite their highly conserved nature, regulate the temperature and chemical gating in the various TRPV channels in different ways.

  3. Thickness of Residual Wetting Film in Liquid-Liquid Displacement in Capillary Channels

    Science.gov (United States)

    Beresnev, I. A.; Gaul, W.; Vigil, D.

    2010-12-01

    Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a non-wetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of this wetting film? Understanding this question may determine the ultimate oil recovery. A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. We develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of about 20 % the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

  4. A novel CaV2.2 channel inhibition by piracetam in peripheral and central neurons.

    Science.gov (United States)

    Bravo-Martínez, Jorge; Arenas, Isabel; Vivas, Oscar; Rebolledo-Antúnez, Santiago; Vázquez-García, Mario; Larrazolo, Arturo; García, David E

    2012-10-01

    No mechanistic actions for piracetam have been documented to support its nootropic effects. Voltage-gated calcium channels have been proposed as a promising pharmacological target of nootropic drugs. In this study, we investigated the effect of piracetam on Ca(V)2.2 channels in peripheral neurons, using patch-clamp recordings from cultured superior cervical ganglion neurons. In addition, we tested if Ca(V)2.2 channel inhibition could be related with the effects of piracetam on central neurons. We found that piracetam inhibited native Ca(V)2.2 channels in superior cervical ganglion neurons in a dose-dependent manner, with an IC(50) of 3.4 μmol/L and a Hill coefficient of 1.1. GDPβS dialysis did not prevent piracetam-induced inhibition of Ca(V)2.2 channels and G-protein-coupled receptor activation by noradrenaline did not occlude the piracetam effect. Piracetam altered the biophysical characteristics of Ca(V)2.2 channel such as facilitation ratio. In hippocampal slices, piracetam and ω-conotoxin GVIA diminished the frequency of excitatory postsynaptic potentials and action potentials. Our results provide evidence of piracetam's actions on Ca(V)2.2 channels in peripheral neurons, which might explain some of its nootropic effects in central neurons.

  5. Identification of a cluster of residues in transmembrane segment 6 of domain III of the cockroach sodium channel essential for the action of pyrethroid insecticides.

    Science.gov (United States)

    Du, Yuzhe; Lee, Jung-Eun; Nomura, Yoshiko; Zhang, Tianxiang; Zhorov, Boris S; Dong, Ke

    2009-04-15

    A phenylalanine residue (Phe1519) in the sixth transmembrane segment of domain III (IIIS6) of the cockroach BgNa(v) sodium channel is required for the binding and action of pyrethroids. However, whether or not other residues in IIIS6 participate in the action of pyrethroids remains to be determined. In the present study, we conducted a systematic analysis of 20 residues in IIIS6 of the BgNa(v) channel using alanine-scanning mutagenesis. Our results show that alanine substitutions of four residues, Ile1514, Gly1516, Phe1518 and Asn1522, altered sodium channel sensitivity to pyrethroid insecticides. Whereas the G1516A, F1518A and N1522A substitutions diminished sodium channel sensitivity to all seven pyrethroids examined, including four type I (lacking the alpha-cyano group at the phenoxybenzyl alcohol) and three type II (containing the alpha-cyano group) pyrethroids, the I1514A substitution enhanced sodium channel sensitivity to four type I and type II pyrethroids that contain the phenoxybenzyl alcohol only. We also show that alanine/lysine substitutions of Leu1521 and Ser1517 affected the action of BTX (batrachotoxin), but not pyrethroids. In the Kv1.2-based homology model of the open sodium channel, side chains of Ile1514, Phe1518 and Asn1522 are exposed towards helix IIS5 and linker IIS4-IIS5, which contain previously identified pyrethroid-interacting residues, whereas Ser1517 and Leu1521 face the inner pore where the BTX receptor is located. Thus the present study provides further evidence for structural models in which pyrethroids bind to the lipid-exposed interface formed by helices IIIS6, IIS5 and linker helix IIS4-IIS5, whereas BTX binds to the pore-exposed side of the IIIS6 helix.

  6. Dataset: Soil erosion and organic matter for central Great Plains cropping systems under residue removal

    Science.gov (United States)

    The diversity of geo-climatic land bases and potential feedstocks within the United States Central Great Plains (CGP) requires sustainable production that provides optimal resource utilization while maintaining or enhancing localized soil and environmental quality as much as possible. This study exa...

  7. Presence and vascular pharmacology of KATP channel subtypes in rat central and peripheral tissues

    DEFF Research Database (Denmark)

    Ploug, Kenneth Beri; Baun, Michael; Hay-Schmidt, Anders

    2010-01-01

    K(ATP) channel openers are vasodilators and induce headache in normal subjects. We previously identified the Kir6.1/SUR2B K(ATP) channel subtype in major cerebral and dural arteries of rat, pig and man. We hypothesized that craniovascular Kir6.1/SUR2B K(ATP) channels mediate the headache-inducing...

  8. Study of Channel Morphology and Infill Lithology in the Wilcox Group Central Louisiana Using Seismic Attribute Analysis

    Science.gov (United States)

    Chen, Feng

    The fluvial and deltaic Wilcox Group is a major target for hydrocarbon and coal exploration in northern and central Louisiana. However, the characterization and delineation of fluvial systems is a difficult task due to the variability and complexity of fluvial systems and their internal heterogeneities. Seismic geomorphology is studied by recognizing paleogeographic features in seismic stratal slices, which are seismic images of paleo-depositional surfaces. Seismic attributes, which are extracted along seismic stratal slices, can reveal information that is not readily apparent in raw seismic data. The existence and distribution of fluvial channels are recognized by the channel geomorphology in seismic attributes displayed on stratal slices. The lithologies in the channels are indicated by those seismic attributes that are directly related to the physical properties of rocks. Selected attributes utilized herein include similarity, spectral decomposition, sweetness, relative acoustic impedance, root mean square (RMS) amplitude, and curvature. Co-rendering and Red/Green/Blue (RGB) display techniques are also included to better illuminate the channel geometry and lithology distribution. Hydrocarbons may exist in the channel sand-bodies, but are not explicitly identified herein. Future drilling plans for oil and gas exploration may benefit from the identification of the channels and the lithologies that fill them.

  9. Arabidopsis TRANSCURVATA1 encodes NUP58, a component of the nucleopore central channel.

    Directory of Open Access Journals (Sweden)

    Almudena Ferrández-Ayela

    Full Text Available The selective trafficking of proteins and RNAs through the nuclear envelope regulates nuclear-cytoplasmic segregation of macromolecules and is mediated by nucleopore complexes (NPCs, which consist of about 400 nucleoporins (Nups of about 30 types. Extensive studies of nucleoporin function in yeast and vertebrates showed that Nups function in nucleocytoplasmic trafficking and other processes. However, limited studies of plant Nups have identified only a few mutations, which cause pleiotropic phenotypes including reduced growth and early flowering. Here, we describe loss-of-function alleles of Arabidopsis TRANSCURVATA1 (TCU1; these mutations cause increased hypocotyl and petiole length, reticulate and asymmetrically epinastic leaf laminae of reduced size, and early flowering. TCU1 is transcribed in all of the organs and tissues examined, and encodes the putative ortholog of yeast and vertebrate Nup58, a nucleoporin of the Nup62 subcomplex. Nup58 forms the central channel of the NPC and acts directly in translocation of proteins through the nuclear envelope in yeast and vertebrates. Yeast two-hybrid (Y2H assays identified physical interactions between TCU1/NUP58 and 34 proteins, including nucleoporins, SCF (Skp1/Cul1/F-box ubiquitin ligase complex components and other nucleoplasm proteins. Genetic interactions were also found between TCU1 and genes encoding nucleoporins, soluble nuclear transport receptors and components of the ubiquitin-proteasome and auxin signaling pathways. These genetic and physical interactions indicate that TCU1/NUP58 is a member of the Nup62 subcomplex of the Arabidopsis NPC. Our findings also suggest regulatory roles for TCU1/NUP58 beyond its function in nucleocytoplasmic trafficking, a hypothesis that is supported by the Y2H and genetic interactions that we observed.

  10. Arabidopsis TRANSCURVATA1 Encodes NUP58, a Component of the Nucleopore Central Channel

    Science.gov (United States)

    Ferrández-Ayela, Almudena; Alonso-Peral, María Magdalena; Pérez-Pérez, José Manuel; Micol, José Luis; Ponce, María Rosa

    2013-01-01

    The selective trafficking of proteins and RNAs through the nuclear envelope regulates nuclear-cytoplasmic segregation of macromolecules and is mediated by nucleopore complexes (NPCs), which consist of about 400 nucleoporins (Nups) of about 30 types. Extensive studies of nucleoporin function in yeast and vertebrates showed that Nups function in nucleocytoplasmic trafficking and other processes. However, limited studies of plant Nups have identified only a few mutations, which cause pleiotropic phenotypes including reduced growth and early flowering. Here, we describe loss-of-function alleles of Arabidopsis TRANSCURVATA1 (TCU1); these mutations cause increased hypocotyl and petiole length, reticulate and asymmetrically epinastic leaf laminae of reduced size, and early flowering. TCU1 is transcribed in all of the organs and tissues examined, and encodes the putative ortholog of yeast and vertebrate Nup58, a nucleoporin of the Nup62 subcomplex. Nup58 forms the central channel of the NPC and acts directly in translocation of proteins through the nuclear envelope in yeast and vertebrates. Yeast two-hybrid (Y2H) assays identified physical interactions between TCU1/NUP58 and 34 proteins, including nucleoporins, SCF (Skp1/Cul1/F-box) ubiquitin ligase complex components and other nucleoplasm proteins. Genetic interactions were also found between TCU1 and genes encoding nucleoporins, soluble nuclear transport receptors and components of the ubiquitin-proteasome and auxin signaling pathways. These genetic and physical interactions indicate that TCU1/NUP58 is a member of the Nup62 subcomplex of the Arabidopsis NPC. Our findings also suggest regulatory roles for TCU1/NUP58 beyond its function in nucleocytoplasmic trafficking, a hypothesis that is supported by the Y2H and genetic interactions that we observed. PMID:23840761

  11. 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.

  12. Channel-lining residues of the AMPA receptor M2 segment: structural environment of the Q/R site and identification of the selectivity filter.

    Science.gov (United States)

    Kuner, T; Beck, C; Sakmann, B; Seeburg, P H

    2001-06-15

    In AMPA receptor channels, a single amino acid residue (Q/R site) of the M2 segment controls permeation of calcium ions, single-channel conductance, blockade by intracellular polyamines, and permeation of anions. The structural environment of the Q/R site and its positioning with regard to a narrow constriction were probed with the accessibility of substituted cysteines to positively and negatively charged methanethiosulfonate reagents, applied from the extracellular and cytoplasmic sides of the channel. The accessibility patterns confirm that the M2 segment forms a pore loop with the Q/R site positioned at the tip of the loop (position 0) facing the extracellular vestibule. Cytoplasmically accessible residues on the N- and C-terminal sides of position 0 form the ascending alpha-helical (-8 to -1) and descending random coil (+1 to +6) components of the loop, respectively. Substitution of a glycine residue at position +2 with alanine strongly decreased the permeability of organic cations, indicating that position +2 contributes to the narrow constriction. The anionic 2-sulfonatoethyl-methanethiosufonate reacted with a cysteine at position 0 only from the external side and with cysteines at positions +1 to +4 only from the cytoplasmic side. These results suggest that charge selectivity occurs external to the constriction (+2) and possibly involves interactions of ions with the negative electrostatic potential created by the dipole of the alpha-helix formed by the ascending limb of the loop.

  13. Two distinct pools of large-conductance calcium-activated potassium channels in the somatic plasma membrane of central principal neurons

    Science.gov (United States)

    Kaufmann, W.A.; Kasugai, Y.; Ferraguti, F.; Storm, J.F.

    2010-01-01

    Although nerve cell membranes are often assumed to be uniform with respect to electrical properties, there is increasing evidence for compartmentalization into subdomains with heterogeneous impacts on the overall cell function. Such microdomains are characterized by specific sets of proteins determining their functional properties. Recently, clustering of large-conductance calcium-activated potassium (BKCa) channels was shown at sites of subsurface membrane cisterns in cerebellar Purkinje cells (PC), where they likely participate in building a subcellular signaling unit, the 'PLasmERosome'. By applying SDS-digested freeze-fracture replica labeling (SDS-FRL) and postembedding immunogold electron microscopy, we have now studied the spatial organization of somatic BKCa channels in neocortical layer 5 pyramidal neurons, principal neurons of the central and basolateral amygdaloid nuclei, hippocampal pyramidal neurons and dentate gyrus (DG) granule cells to establish whether there is a common organizational principle in the distribution of BKCa channels in central principal neurons. In all cell types analyzed, somatic BKCa channels were found to be non-homogenously distributed in the plasma membrane, forming two pools of channels with one pool consisting of clustered channels and the other of scattered channels in the extrasynaptic membrane. Quantitative analysis by means of SDS-FRL revealed that about two-thirds of BKCa channels belong to the scattered pool and about one-third to the clustered pool in principal cell somata. Overall densities of channels in both pools differed in the different cell types analyzed, although being considerably lower compared to cerebellar PC. Postembedding immunogold labeling revealed association of clustered channels with subsurface membrane cisterns and confirmed extrasynaptic localization of scattered channels. This study indicates a common organizational principle for somatic BKCa channels in central principal neurons with the

  14. SUMOylation of NaV1.2 channels mediates the early response to acute hypoxia in central neurons

    Science.gov (United States)

    Plant, Leigh D; Marks, Jeremy D; Goldstein, Steve AN

    2016-01-01

    The mechanism for the earliest response of central neurons to hypoxia—an increase in voltage-gated sodium current (INa)—has been unknown. Here, we show that hypoxia activates the Small Ubiquitin-like Modifier (SUMO) pathway in rat cerebellar granule neurons (CGN) and that SUMOylation of NaV1.2 channels increases INa. The time-course for SUMOylation of single NaV1.2 channels at the cell surface and changes in INa coincide, and both are prevented by mutation of NaV1.2-Lys38 or application of a deSUMOylating enzyme. Within 40 s, hypoxia-induced linkage of SUMO1 to the channels is complete, shifting the voltage-dependence of channel activation so that depolarizing steps evoke larger sodium currents. Given the recognized role of INa in hypoxic brain damage, the SUMO pathway and NaV1.2 are identified as potential targets for neuroprotective interventions. DOI: http://dx.doi.org/10.7554/eLife.20054.001 PMID:28029095

  15. Role of glycine residues highly conserved in the S2-S3 linkers of domains I and II of voltage-gated calcium channel alpha(1) subunits.

    Science.gov (United States)

    Teng, Jinfeng; Iida, Kazuko; Ito, Masanori; Izumi-Nakaseko, Hiroko; Kojima, Itaru; Adachi-Akahane, Satomi; Iida, Hidetoshi

    2010-05-01

    The pore-forming component of voltage-gated calcium channels, alpha(1) subunit, contains four structurally conserved domains (I-IV), each of which contains six transmembrane segments (S1-S6). We have shown previously that a Gly residue in the S2-S3 linker of domain III is completely conserved from yeasts to humans and important for channel activity. The Gly residues in the S2-S3 linkers of domains I and II, which correspond positionally to the Gly in the S2-S3 linker of domain III, are also highly conserved. Here, we investigated the role of the Gly residues in the S2-S3 linkers of domains I and II of Ca(v)1.2. Each of the Gly residues was replaced with Glu or Gln to produce mutant Ca(v)1.2s; G182E, G182Q, G579E, G579Q, and the resulting mutants were transfected into BHK6 cells. Whole-cell patch-clamp recordings showed that current-voltage relationships of the four mutants were the same as those of wild-type Ca(v)1.2. However, G182E and G182Q showed significantly smaller current densities because of mislocalization of the mutant proteins, suggesting that Gly(182) in domain I is involved in the membrane trafficking or surface expression of alpha(1) subunit. On the other hand, G579E showed a slower voltage-dependent current inactivation (VDI) compared to Ca(v)1.2, although G579Q showed a normal VDI, implying that Gly(579) in domain II is involved in the regulation of VDI and that the incorporation of a negative charge alters the VDI kinetics. Our findings indicate that the two conserved Gly residues are important for alpha(1) subunit to become functional.

  16. REACH SPECIFIC CHANNEL STABILIZATION BASED ON COMPREHENSIVE EVALUATION OF VALLEY FILL HISTORY, ALLUVIAL ARCHITECTURE AND GROUNDWATER HYDROLOGY IN A MOUNTAIN STREAM IN THE CENTRAL GREAT BASIN, NEVADA

    Science.gov (United States)

    Kingston meadow, located in the Toiyabe Range, is one of many wet meadow complexes threatened by rapid channel incision in the mountain ranges of the central Great Basin. Channel incision can lower the baselevel for groundwater discharge and de-water meadow complexes resulting in...

  17. Role of highly central residues of P-loop and it's flanking region in preserving the archetypal conformation of Walker A motif of diverse P-loop NTPases.

    Science.gov (United States)

    Pathak, Ekta; Atri, Neelam; Mishra, Rajeev

    2013-01-01

    P-loop NTPases represent a large and highly diverse protein family that is involved in variety of cellular functions. Walker A motif forms a typical arched conformation, necessary to accommodate the phosphate moiety of the nucleoside tri (or di-) phosphate in Ploop NTPases. The feature that maintains the ancient architecture of P-loop is unidentified and uncharacterized. Here, using a well established global network parameter, closeness centrality, we identify that Walker A and its flanking regions (N- and C-terminal) have high density of globally connected residue positions. We find that closeness centrality of these residue positions are conserved across common structural core of diverse domains of P-loop NTPase fold. Our results suggest the potential role of globally connected residues in maintaining the local conformation of P-loop.

  18. Oxidation of KCNB1 K~+ channels in central nervous system and beyond

    Institute of Scientific and Technical Information of China (English)

    Federico; Sesti; Xilong; Wu; Shuang; Liu

    2014-01-01

    KCNB1, a voltage-gated potassium(K+) channel that conducts a major delayed rectifier current in the brain, pancreas and cardiovascular system is a key player in apoptotic programs associated with oxidative stress. As a result, this protein represents a bona fide drug target for limiting the toxic effects of oxygen radicals. Until recently the consensus view was that reactive oxygen species trigger a pro-apoptotic surge in KCNB1 current via phosphorylation and SNARE-dependent incorpora-tion of KCNB1 channels into the plasma membrane. However, new evidence shows that KCNB1 can be modified by oxidants and that oxidized KCNB1 channels can directly activate pro-apoptotic signaling pathways. Hence, a more articulated picture of the pro-apoptotic role of KCNB1 is emerging in which the protein induces cell’s death through distinct molecular mechanisms and activation of multiple pathways. In this review article we discuss the diverse functional, toxic and protective roles that KCNB1 channels play in the major organs where they are expressed.

  19. The Mechanosensitive Ca2+ Channel as a Central Regular of Prostate Tumor Cell Migration and Invasiveness

    Science.gov (United States)

    2011-04-01

    et al. 1995); initial heterologous expression of human TRPC1 in CHO and sf9 cells showed enhanced SOC currents (Zitt et al. 1996). However, a...subsequent study indicated that hTRPC1 expression in sf9 cells induced a constitutively active nonselective cation channel that was not sensitive to

  20. A study of the $\\omega\\omega$ channel produced in central pp interactions at 450 GeV/c

    CERN Document Server

    Barberis, D; Close, Francis Edwin; Danielsen, K M; Donskov, S V; Earl, B C; Evans, D; French, Bernard R; Hino, T; Inaba, S; Jacholkowski, A; Jacobsen, T; Khaustov, G V; Kinson, J B; Kirk, A; Kondashov, A A; Lednev, A A; Lenti, V; Minashvili, I A; Peigneux, J P; Romanovsky, V I; Rusakovitch, N A; Semenov, A A; Shagin, P M; Shimizu, H; Singovsky, A V; Sobol, A E; Stassinaki, M; Stroot, Jean-Pierre; Takamatsu, K; Tsuru, T; Villalobos Baillie, O; Votruba, M F; Yasu, Y

    2000-01-01

    The reaction pp -> pf (omega omega) ps has been studied at 450 GeV/c and a spin analysis of the omega omega channel has been performed for the first time in central production. Evidence is found for the f2(1910) in the JPC = 2++ wave with spin projection JZ = 2. This is the only state observed in central production with spin projection JZ = 2. Its dPT and phi dependencies are similar to those observed for other glueball candidates. In addition, evidence is found for a state with JPC = 4++ consistent with the f4(2300). The f0(2000), previously observed in the rho rho final state, is confirmed.

  1. Kv channel gating requires a compatible S4-S5 linker and bottom part of S6, constrained by non-interacting residues.

    Science.gov (United States)

    Labro, Alain J; Raes, Adam L; Grottesi, Alessandro; Van Hoorick, Diane; Sansom, Mark S P; Snyders, Dirk J

    2008-12-01

    Voltage-dependent K(+) channels transfer the voltage sensor movement into gate opening or closure through an electromechanical coupling. To test functionally whether an interaction between the S4-S5 linker (L45) and the cytoplasmic end of S6 (S6(T)) constitutes this coupling, the L45 in hKv1.5 was replaced by corresponding hKv2.1 sequence. This exchange was not tolerated but could be rescued by also swapping S6(T). Exchanging both L45 and S6(T) transferred hKv2.1 kinetics to an hKv1.5 background while preserving the voltage dependence. A one-by-one residue substitution scan of L45 and S6(T) in hKv1.5 further shows that S6(T) needs to be alpha-helical and forms a "crevice" in which residues I422 and T426 of L45 reside. These residues transfer the mechanical energy onto the S6(T) crevice, whereas other residues in S6(T) and L45 that are not involved in the interaction maintain the correct structure of the coupling.

  2. Residue Phe266 in S5-S6 loop is not critical for Charybdotoxin binding to Ca2+-activated K+ (mSlo1) channels

    Institute of Scientific and Technical Information of China (English)

    Jing YAO; Hui LI; Ge-liang GAN; Ying WU; Jiu-ping DING

    2006-01-01

    Aim: To gain insight into the interaction between the Charybdotoxin (ChTX) and BK channels. Methods: Site-directed mutagenesis was used to make two mutants: mSlo1-F266L and mSlo1-F266A. The two mutants were then expressed in Xeno-pus oocytes and their effects were tested on ChTX by electrophysiology experiments. Results: We demonstrate an equilibrium dissociation constant Kd= 3.1-4.2 nmol/L for both the mutants mSlo1-F266L and mSlo1-F266A similar to that of the wild-type mSlo1 Kd=3.9 nmol/L. Conclusion: The residue Phe266 does not play a crucial role in binding to ChTX, which is opposed to the result arising from the simulation of peptide-channel interaction.

  3. A study of the $\\eta \\eta{'}$ and $\\eta{'}\\eta{'}$ channels produced in central p p interactions at 450 GeV/c

    CERN Document Server

    Barberis, D

    2000-01-01

    The reactions pp -> pf (X0) ps, where X0 is observed decaying to eta etaprime and etaprime etaprime, have been studied at 450 GeV/c. This is the first time that these channels have been observed in central production and only the second time that the etaprime etaprime channel has been observed in any production mechanism. In the eta etaprime channel there is evidence for the f0(1500) and a peak at 1.95 GeV. The etaprime etaprime channel shows a peak at threshold which is compatible with having JPC = 2++ and spin projection JZ = 0.

  4. The Mechanosensory Ca2+ Channel as a Central Regulator of Prostate Tumor Cell Migration and Invasiveness

    Science.gov (United States)

    2008-01-01

    hamster ovary (CHO) and sf9 cells enhanced SOC currents (Zitt et al., 1996). However, a subsequent study indicated hTRPC1 expression in sf9 cells induced...Zhu et al. 1995); initial heterologous expression of human TRPC1 in CHO and sf9 cells showed enhanced SOC currents (Zitt et al. 1996). However, a...subsequent study indicated that hTRPC1 expression in sf9 cells induced a constitutively active nonselective cation channel that was not sensitive to

  5. Effects of stress shielding and subsequent restressing on mechanical properties of regenerated and residual tissues in rabbit patellar tendon after resection of its central one-third.

    Science.gov (United States)

    Maeda, Eijiro; Asanuma, Hiroyuki; Noguchi, Hitoshi; Tohyama, Harukazu; Yasuda, Kazunori; Hayashi, Kozaburo

    2009-08-07

    Central third of patellar tendon (PT) is used as an autograft for anterior cruciate ligament (ACL) reconstruction. Previous studies investigated temporal changes in material properties of healing tissues in PT after resection of the central third. However, no study has been performed on effects of stress shielding (SS) and restressing (RS) on the properties of healing tissues. The present study hypothesised that SS adversely affects the mechanical integrity of healing tissues, which is recovered by subsequent RS. An entire rectangular defect was created in the central third of rabbit PT. Operated PTs were subjected to either SS or no stress shielding (NSS). A subgroup of stress-shielded PTs was followed by the resumption of normal loading, namely RS. Tensile properties of tissues regenerated in the defect and residual tendons were evaluated. Regenerated tissues of SS for 3 weeks resulted in significantly lower strength than NSS, which was recovered to NSS level by 3 weeks of RS. Strength of residual tissues in RS reversed SS effects, leading to the strength at NSS level after 12 weeks. However, tangent modulus of residual tissues in RS was still significantly lower than that of NSS at 12 weeks. Therefore, SS induces detrimental effects on the mechanical integrity of healing PTs, and the response to RS was different between regenerate and residual tissues, the latter of which took longer period to reach NSS level.

  6. Investigation of thermal energy transport from an anisotropic central heating element to the adjacent channels: A multipoint flux approximation

    KAUST Repository

    Salama, Amgad

    2015-02-01

    The problem of heat transfer from a central heating element pressed between two clad plates to cooling channels adjacent and outboard of the plates is investigated numerically. The aim of this work is to highlight the role of thermal conductivity anisotropy of the heating element and/or the encompassing plates on thermal energy transport to the fluid passing through the two channels. When the medium is anisotropic with respect to thermal conductivity; energy transport to the neighboring channels is no longer symmetric. This asymmetry in energy fluxes influence heat transfer to the coolant resulting in different patterns of temperature fields. In particular, it is found that the temperature fields are skewed towards the principal direction of anisotropy. In addition, the heat flux distributions along the edges of the heating element are also different as a manifestation of thermal conductivity anisotropy. Furthermore, the peak temperature at the channel walls change location and magnitude depending on the principal direction of anisotropy. Based on scaling arguments, it is found that, the ratio of width to the height of the heating system is a key parameter which can suggest when one may ignore the effect of the cross-diagonal terms of the full conductivity tensor. To account for anisotropy in thermal conductivity, the method of multipoint flux approximation (MPFA) is employed. Using this technique, it is possible to find a finite difference stencil which can handle full thermal conductivity tensor and in the same time enjoys the simplicity of finite difference approximation. Although the finite difference stencil based on MPFA is quite complex, in this work we apply the recently introduced experimenting field approach which construct the global problem automatically.

  7. Aromatic-aromatic interactions between residues in KCa3.1 pore helix and S5 transmembrane segment control the channel gating process.

    Science.gov (United States)

    Garneau, Line; Klein, Hélène; Lavoie, Marie-France; Brochiero, Emmanuelle; Parent, Lucie; Sauvé, Rémy

    2014-02-01

    The Ca(2+)-activated potassium channel KCa3.1 is emerging as a therapeutic target for a large variety of health disorders. One distinguishing feature of KCa3.1 is that the channel open probability at saturating Ca(2+) concentrations (Pomax) is low, typically 0.1-0.2 for KCa3.1 wild type. This observation argues for the binding of Ca(2+) to the calmodulin (CaM)-KCa3.1 complex, promoting the formation of a preopen closed-state configuration leading to channel opening. We have previously shown that the KCa3.1 active gate is most likely located at the level of the selectivity filter. As Ca(2+)-dependent gating of KCa3.1 originates from the binding of Ca(2+) to CaM in the C terminus, the hypothesis of a gate located at the level of the selectivity filter requires that the conformational change initiated in the C terminus be transmitted to the S5 and S6 transmembrane helices, with a resulting effect on the channel pore helix directly connected to the selectivity filter. A study was thus undertaken to determine to what extent the interactions between the channel pore helix with the S5 and S6 transmembrane segments contribute to KCa3.1 gating. Molecular dynamics simulations first revealed that the largest contact area between the pore helix and the S5 plus S6 transmembrane helices involves residue F248 at the C-terminal end of the pore helix. Unitary current recordings next confirmed that modulating aromatic-aromatic interactions between F248 and W216 of the S5 transmembrane helical segment and/or perturbing the interactions between F248 and residues in S6 surrounding the glycine hinge G274 cause important changes in Pomax. This work thus provides the first evidence for a key contribution of the pore helix in setting Pomax by stabilizing the channel closed configuration through aromatic-aromatic interactions involving F248 of the pore helix. We propose that the interface pore helix/S5 constitutes a promising site for designing KCa3.1 potentiators.

  8. Identification of Amino Acid Residues in Fibroblast Growth Factor 14 (FGF14) Required for Structure-Function Interactions with Voltage-gated Sodium Channel Nav1.6.

    Science.gov (United States)

    Ali, Syed R; Singh, Aditya K; Laezza, Fernanda

    2016-05-20

    The voltage-gated Na(+) (Nav) channel provides the basis for electrical excitability in the brain. This channel is regulated by a number of accessory proteins including fibroblast growth factor 14 (FGF14), a member of the intracellular FGF family. In addition to forming homodimers, FGF14 binds directly to the Nav1.6 channel C-tail, regulating channel gating and expression, properties that are required for intrinsic excitability in neurons. Seeking amino acid residues with unique roles at the protein-protein interaction interface (PPI) of FGF14·Nav1.6, we engineered model-guided mutations of FGF14 and validated their impact on the FGF14·Nav1.6 complex and the FGF14:FGF14 dimer formation using a luciferase assay. Divergence was found in the β-9 sheet of FGF14 where an alanine (Ala) mutation of Val-160 impaired binding to Nav1.6 but had no effect on FGF14:FGF14 dimer formation. Additional analysis revealed also a key role of residues Lys-74/Ile-76 at the N-terminal of FGF14 in the FGF14·Nav1.6 complex and FGF14:FGF14 dimer formation. Using whole-cell patch clamp electrophysiology, we demonstrated that either the FGF14(V160A) or the FGF14(K74A/I76A) mutation was sufficient to abolish the FGF14-dependent regulation of peak transient Na(+) currents and the voltage-dependent activation and steady-state inactivation of Nav1.6; but only V160A with a concomitant alanine mutation at Tyr-158 could impede FGF14-dependent modulation of the channel fast inactivation. Intrinsic fluorescence spectroscopy of purified proteins confirmed a stronger binding reduction of FGF14(V160A) to the Nav1.6 C-tail compared with FGF14(K74A/I76A) Altogether these studies indicate that the β-9 sheet and the N terminus of FGF14 are well positioned targets for drug development of PPI-based allosteric modulators of Nav channels.

  9. Drivers of residual estuarine circulation in tidally energetic estuaries: straight and irrotational channels with parabolic cross section

    NARCIS (Netherlands)

    Burchard, H.; Hetland, R.D.; Schulz, E.; Schuttelaars, H.M.

    2011-01-01

    The generation of residual circulation in a tidally energetic estuary with constant longitudinal salinity gradient and parabolic cross section is examined by means of a two-dimensional cross-sectional numerical model, neglecting river runoff and Stokes drift. It is shown how the longitudinal and lat

  10. 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, Franklin T.; Hudson, Paul F.; Asquith, William H.

    2015-03-01

    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 (excess of 200 watts per square meter (W/m2); and (vi) downstream convergence of hydraulic geometry exponents for bankfull and macrochannels, explained by co-increases of flood magnitude and noncohesive sandy sediments that collectively minimize development of alluvial bankfull indicators. Collectively, these findings indicate

  11. Determination of niclosamide residues in rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) fillet tissue by high-performance liquid chromatography

    Science.gov (United States)

    Schreier, T.M.; Dawson, V.K.; Cho, Yirang; Spanjers, N.J.; Boogaard, M.A.

    2000-01-01

    Bayluscide [the ethanolamine salt of niclosamide (NIC)] is a registered piscicide used in combination with 3-(trifluoromethyl)-4-nitrophenol (TFM) to control sea lamprey populations in streams tributary to the Great Lakes. A high-performance liquid chromatography (HPLC) method was developed for the determination of NIC residues in muscle fillet tissues of fish exposed to NIC and TFM during sea lamprey control treatments. NIC was extracted from fortified channel catfish and rainbow trout fillet tissue with a series of acetone extractions and cleaned up on C-18 solid-phase extraction cartridges. NIC concentrations were determined by HPLC with detection at 360 and 335 nm for rainbow trout and catfish, respectively. Recovery of NIC from rainbow trout (n = 7) fortified at 0.04 mu g/g was 77 +/- 6.5% and from channel catfish (n = 7) fortified at 0.02 mu g/g was 113 +/- 11%. NIC detection limit was 0.0107 mu g/g for rainbow trout and 0.0063 mu g/g for catfish. Percent recovery of incurred radioactive residues by this method from catfish exposed to [C-14]NIC was 89.3 +/- 4.1%. Percent recoveries of NIC from fortified storage stability tissue samples for rainbow trout (n = 3) analyzed at 5 and 7.5 month periods were 78 +/- 5.1 and 68 +/- 2.4%, respectively. Percent recoveries of NIC from fortified storage stability tissue samples for channel catfish (n = 3) analyzed at 5 and 7.5 month periods were 88 +/- 13 and 76 +/- 21%, respectively.

  12. Mound Spring Complexes in Central Australia: An Analog for Martian Groundwater Fed Outflow Channels?

    Science.gov (United States)

    Clarke, J. D. A.; Stoker, C.

    2003-01-01

    The arid inland of Australia contains a diversity of landscapes and landscape processes, often of great antiquity, extending back to the Mesozoic and Paleozoic. The potential of this landscape as a source of Mars analogs has, however, been little explored. The few examples studied so far include radiation-tolerant microbes in thermal springs and hematite-silica hydrothermal alteration near Arkaroola in the Finders Ranges, and aeolian landforms at Gurra Gurra water hole the north east of Arkaroola. Further Australian Mars analog studies were provided by the studies of Bourke and Zimbelman of the paleoflood record of the Todd and Hale Rivers in central Australia. To facilitate study of such analogues, Mars Society Australia has embarked on a project to construct a Mars Analog Research Station near Arkaroola. The international scientific community will soon have the opportunity to participate in Mars analog studies in central Australia utilizing this facility. An area of considerable Mars analog potential is the mound spring complexes that occur at the margins of the Great Artesian Basin (GAB) which underlies 22% of the Australian continent and covers 1.7 million km2. The mound springs are formed when ground water flows to a topographic low, and subsurface strata dips up causing a hydrological head at the surface. Minerals precipitated at the spring discharge zone form low mesas or "mounds", the height of which are controlled by the hydrological head. This paper describes the Dalhousie Mound Spring Complex (DMC) in the northern part of South Australia (Figure 1), and its potential as a Mars analog. Hydrogeology: The DMC consists of a cluster of more than 60 active springs formed by natural discharge from the GAB). Total measured discharge from the GAB is 1.74 GL per day, estimated unfocussed natural leakage through the aquaclude is thought be approximately equal to this figure. Some 54 ML per day are currently discharged by the DMC, 3% of the measured total. The

  13. Deep dynamical processes in the central-southern Qinghai-Tibet Plateau—Receiver functions and travel-time residuals analysis of north Hi-Climb

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Teleseismic receiver functions and travel-time residuals along the north Hi-Climb broadband seismic array in the central-southern Qinghai-Tibet Plateau show that the lithosphere structures in the central and western Qinghai-Tibet Plateau are different. In the central Qinghai-Tibet Plateau, the Indian Plate is northward subducted beneath the Qiangtang block and arrives at the greatest depth beneath the central-southern Qiangtang block. The delaminated Indian lithospheric slab remains beneath the central Lhasa block to a depth possibly greater than that of the upper interface of the mantle transform zone. In the western Qinghai-Tibet Plateau, the Indian lithospheric plate is gently northward subducted and may have arrived to the south of Tarim plate. Due to the resistance from the gently northward subduction of the Indian mantle lithosphere in the western Qinghai-Tibet Plateau, the upwelling mantle material be-neath the Qiangtang block moves mostly toward the east to bring about the lateral eastward flow of the deep mantle hot material in the central Qinghai-Tibet Plateau.

  14. Deep dynamical processes in the central-southern Qinghai-Tibet Plateau——Receiver functions and travel-time residuals analysis of north Hi-Climb

    Institute of Scientific and Technical Information of China (English)

    LI HaiOu; XU XiWei; JIANG Mei

    2008-01-01

    Teleseismic receiver functions and travel-time residuals along the north Hi-Climb broadband seismic array in the central-southern Qinghai-Tibet Plateau show that the lithosphere structures in the central and western Qinghai-Tibet Plateau are different.In the central Qinghai-Tibet Plateau, the Indian Plate is northward subducted beneath the Qiangtang block and arrives at the greatest depth beneath the central-southern Qiangtang block.The delaminated Indian lithospheric slab remains beneath the central Lhasa block to a depth possibly greater than that of the upper interface of the mantle transform zone.In the western Qinghai-Tibet Plateau, the Indian lithospheric plate is gently northward subducted and may have arrived to the south of Tarim plate.Due to the resistance from the gently northward subduction of the Indian mantle lithosphere in the western Qinghai-Tibet Plateau, the upwelling mantle material beneath the Qiangtang block moves mostly toward the east to bring about the lateral eastward flow of the deep mantle hot material in the central Qinghai-Tibet Plateau.

  15. Adsorption of charged protein residues on an inorganic nanosheet: Computer simulation of LDH interaction with ion channel

    Science.gov (United States)

    Tsukanov, Alexey A.; Psakhie, Sergey G.

    2016-08-01

    Quasi-two-dimensional and hybrid nanomaterials based on layered double hydroxides (LDH), cationic clays, layered oxyhydroxides and hydroxides of metals possess large specific surface area and strong electrostatic properties with permanent or pH-dependent electric charge. Such nanomaterials may impact cellular electrostatics, changing the ion balance, pH and membrane potential. Selective ion adsorption/exchange may alter the transmembrane electrochemical gradient, disrupting potential-dependent cellular processes. Cellular proteins as a rule have charged residues which can be effectively adsorbed on the surface of layered hydroxide based nanomaterials. The aim of this study is to attempt to shed some light on the possibility and mechanisms of protein "adhesion" an LDH nanosheet and to propose a new direction in anticancer medicine, based on physical impact and strong electrostatics. An unbiased molecular dynamics simulation was performed and the combined process free energy estimation (COPFEE) approach was used.

  16. Fluid escape structures in the Graham Bank region (Sicily Channel, Central Mediterranean) revealing volcanic and neotectonic activity.

    Science.gov (United States)

    Spatola, Daniele; Pennino, Valentina; Basilone, Luca; Interbartolo, Francesco; Micallef, Aaron; Sulli, Attilio; Basilone, Walter

    2016-04-01

    In the Sicily Channel, (Central Mediterranean), two geodynamic processes overlap each other, the Maghrebides-Apennines accretionary prism and the Sicily Channel rift. Moreover, the northwestern sector (Banks sector) is characterised by an irregular seafloor morphology linked to the recent volcanic and tectonic activity.In order to discriminate the role exerted by both the processes in the morphostructural setting of the area we used a dataset of both high and very high resolution single-channel and multi-channel profiles, acquired in the frame of the RITMARE project respectively with CHIRP and sparker, and airgun sources, and high resolution (5 m cell) morpho-bathymetric data. The data allowed us to identify and characterise two areas where different geological features (sedimentary and volcanic) are prevailing. They present fluid escaping evidence, which often appears to be active and generating different types of morphologies (both positive and negative). In the western sector we recognised pockmarks at water depths of 195 to 317 m, with diameters from 25 to 580 m, depths from 1.3 to 15 m, and slope up to 23°. They show sub-circular shape in plan-view and reflectors with upward concavity in cross section, and are oriented along a NW-SE trend.The CHIRP and multichannel profiles highlight fluids that affect the Plio-Quaternary succession, especially in areas where the top surface of the Messinian succession is shallower. Conversely, wipe-out acoustic facies were recognised in proximity of: i) extensional faults of Mesozoic age with NW-SE trend; ii) dip/strike slip faults of Cenozoic age with NW-SE, N-S and about NNE-SSW trends, and iii) extensional neo-tectonic faults with NW-SE and NNW-SSE trends. We cannot exclude that they could feed the shallower reservoir producing a mixing between the two. In the eastern sector we recognised a cluster of volcanoes composed of seven cone-shaped structures (SCV1-7), pertaining to a wide area known as Graham Bank. A detailed

  17. Comparative ecobalancing accounting of semi-central house heat supply from wood residues; Vergleichende Oekobilanzierung der semi-zentralen Hauswaermebereitstellung aus Holzreststoffen

    Energy Technology Data Exchange (ETDEWEB)

    Biemann, Kirsten

    2015-07-01

    In 2008 almost 40 percent of the German final energy demand was used for room heating and hot water supply. To decrease environmental burdens and to save fossil resources a restructuring of the heating sector is needed. Therefore legislation enforces higher insulation standards of buildings and a more frequent use of renewable energies as well as heating networks. Wood as a renewable and storable energy source is an attractive fuel. However, it must be used as efficiently as possible because of limited wood supplies. Connecting buildings via a heating network is a good option since bigger heating plants can operate at higher efficiencies than small heaters. However, the higher insulation standards of the buildings often oppose the construction of a heating network, because heating networks work best with high energy demands and low network lengths. Therefore the environmental and economic feasibility of new heating networks needs to be checked beforehand. This thesis explores the environmental burdens of different semi- centralized heating networks using wood residues as fuel. A semi- centralized heating network is a network with no more than 500 customers and a heating plant with less than 5 MWth. While wood residues are used in the base load plant, peak load is covered by a gas heating plant. As a method to analyze the potential environmental burdens of the heat supply a life cycle assessment according to ISO 14040/44 is used. Opposed to former life cycle assessment studies, construction and operation of the network is included in the assessment. Even though the environmental impacts of the semi- centralized heating from wood residues are dominated by the heat supply, an observation of the impacts solely at the heating plant is not sufficient. By varying the boundary conditions of the heating network two main contributors to the environmental impacts are found. In addition to the heat production at the plant the type of the buildings in the settlement has a huge

  18. Nanofiltration and sensing of picomolar chemical residues in aqueous solution using an optical porous resonator in a microelectrofluidic channel

    Science.gov (United States)

    Huang, Lei; Guo, Zhixiong

    2012-02-01

    For the first time the use of a porous microresonator placed in a microelectrofluidic system for integrated functions of nanofiltration and sensing of small biomolecules and chemical analytes in extremely dilute solution was proposed and investigated. As an example, aminoglycosides in drug residues in food and livestock products were considered as the trace chemical analyte. The filtration process of the charged analyte in aqueous solution driven by an applied electrical field and the accompanying optical whispering-gallery modes in the resonator are modeled. The dynamic process of adsorption and desorption of the analyte onto the porous matrix is studied. Deposition of the analyte inside the porous structure will alter the material refractive index of the resonator, and thus induce an optical resonance frequency shift. By measuring the optical frequency shift, the analyte concentration as well as the absorption/desorption process can be analyzed. Through an intensive numerical study, a correlation between the frequency shift and the analyte concentration and the applied electrical voltage gradient was obtained. This reveals a linear relationship between the resonance frequency shift and the analyte concentration. The applied electrical voltage substantially enhances the filtration capability and the magnitude of the optical frequency shift, pushing the porous resonator-based sensor to function at the extremely dilute picomolar concentration level for small bio/chemical molecules down to the sub-nanometer scale. Moreover, use of the second-order whispering-gallery mode is found to provide better sensitivity compared with the first-order mode.

  19. A study of the $\\eta \\eta'$ and $\\eta' \\eta'$ channels produced in central pp interactions at 450 GeV/c

    CERN Document Server

    Barberis, D; Close, Francis Edwin; Danielsen, K M; Donskov, S V; Earl, B C; Evans, D; French, Bernard R; Hino, T; Inaba, S; Jacholkowski, A; Jacobsen, T; Khaustov, G V; Kinson, J B; Kirk, A; Kondashov, A A; Lednev, A A; Lenti, V; Minashvili, I A; Peigneux, J P; Romanovsky, V I; Rusakovitch, N A; Semenov, A A; Shagin, P M; Shimizu, H; Singovsky, A V; Sobol, A E; Stassinaki, M; Stroot, Jean-Pierre; Takamatsu, K; Tsuru, T; Villalobos Baillie, O; Votruba, M F; Yasu, Y

    2000-01-01

    The reactions pp to p/sub f/(X/sup 0/)p/sub s/, where X/sup 0/ is observed decaying to eta eta ' and eta ' eta ', have been studied at 450 GeV/c. This is the first time that these channels have been observed in central production and only the second time that the eta ' eta ' channel has been observed in any production mechanism. In the eta eta ' channel there is evidence for the f/sub 0/(1500) and a peak at 1.95 GeV. The eta ' eta ' channel shows a peak at threshold which is compatible with having J/sup PC/=2/sup ++/ and spin projection J /sub Z/=0. (13 refs).

  20. 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 (values (most ≤ 0.45) that develop at sites with unit stream power values in excess of 200 watts per square meter (W/m2); and (vi) downstream convergence of hydraulic geometry exponents for bankfull and macrochannels, explained by co-increases of flood magnitude and noncohesive sandy sediments that collectively minimize

  1. Determination of activity by gamma spectrometry of radionuclides present in drums of residues generated in nuclear centrals; Determinacion de actividad por espectrometria gamma de radionucleidos presentes en tambores de residuos generados en centrales nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, J.C.; Fernandez, J. [Autoridad Regulatoria Nuclear, Av. Del Libertador 8250, Ciudad Autonoma de Buenos Aires (Argentina)]. e-mail: jaguiar@cae.arn.gov.ar

    2006-07-01

    The generation of radioactive residuals in nuclear centrals as CNA I (Atucha I Nuclear Central) and CNE (Embalse Nuclear Central) makes that the measurement of those radionuclides has been a previous stage to the waste management. A method used in those nuclear centrals it is the gamma spectrometry with HPGe detectors, previous to the immobilization of the residual in a cemented matrix, with this the contact with the external agents and its possible dispersion to the atmosphere in the short term is avoided. The ARN (Nuclear Regulatory Authority) of Argentina it carries out periodically intercomparisons and evaluations of the measurement and procedures systems used in the nuclear power stations for the correct measurement and determination of activity of radioactive residuals by gamma spectrometry. In this work an independent method of measurement is exposed to the nuclear power stations. To determine the activity of the residuals by gamma spectrometry deposited in drums, it is required of the precise knowledge of the efficiency curve for such geometry and matrix. Due to the RNA doesn't have a pattern of these characteristics, a mathematical model has been used to obtain this efficiency curve. For it, it is necessary to determine previously: 1) the geometric efficiency or solid angle sustained by the source-detector system (drum-detector) applying a mathematical model described in this work. 2) To estimate the auto-attenuation factor that present the photons in the cemented matrix, these calculations are carried out with a simple equation and its are verified with the Micro Shield 6.10 program. The container commonly used by these nuclear power stations its are drums for 220 liters constructed with SAE 1010 steel and with a thickness of 0.127 cm, with an approximate weight 7.73 Kg., internal diameter of 57.1 cm, and height: 87 cm. The results obtained until the moment register a discrepancy from 5 to 10% with relationship to the measurements carried out by the

  2. Life cycle assessment of post-consumer plastics production from waste electrical and electronic equipment (WEEE) treatment residues in a Central European plastics recycling plant

    Energy Technology Data Exchange (ETDEWEB)

    Wäger, Patrick A., E-mail: patrick.waeger@empa.ch; Hischier, Roland

    2015-10-01

    Plastics play an increasingly important role in reaching the recovery and recycling rates defined in the European WEEE Directive. In a recent study we have determined the life cycle environmental impacts of post-consumer plastics production from mixed, plastics-rich WEEE treatment residues in the Central European plant of a market-leading plastics recycler, both from the perspective of the customers delivering the residues and the customers buying the obtained post-consumer recycled plastics. The results of our life cycle assessments, which were extensively tested with sensitivity analyses, show that from both perspectives plastics recycling is clearly superior to the alternatives considered in this study (i.e. municipal solid waste incineration (MSWI) and virgin plastics production). For the three ReCiPe endpoint damage categories, incineration in an MSWI plant results in an impact exceeding that of the examined plastics recycling facility each by about a factor of 4, and the production of virgin plastics has an impact exceeding that of the post-consumer recycled (PCR) plastics production each by a factor of 6–10. On a midpoint indicator level the picture is more differentiated, showing that the environmental impacts of the recycling options are lower by 50% and more for almost all impact factors. While this provides the necessary evidence for the environmental benefits of plastics recycling compared to existing alternatives, it can, however, not be taken as conclusive evidence. To be conclusive, future research will have to address the fate of hazardous substances in the outputs of such recycling systems in more detail. - Highlights: • LCA of plastics production from plastics-rich WEEE treatment residues • Multiple stakeholder perspectives addressed via different research questions • Plastics production from WEEE treatment residues clearly superior to alternatives • Robust results as demonstrated by extensive sensitivity analyses.

  3. Shaker-Related Potassium Channels in the Central Medial Nucleus of the Thalamus Are Important Molecular Targets for Arousal Suppression by Volatile General Anesthetics

    Science.gov (United States)

    Birch, Alexandra M.; Tanaka, Brian S.; Sokolov, Yuri; Goldin, Alan L.; Chandy, K. George; Hall, James E.; Alkire, Michael T.

    2013-01-01

    The molecular targets and neural circuits that underlie general anesthesia are not fully elucidated. Here, we directly demonstrate that Kv1-family (Shaker-related) delayed rectifier K+ channels in the central medial thalamic nucleus (CMT) are important targets for volatile anesthetics. The modulation of Kv1 channels by volatiles is network specific as microinfusion of ShK, a potent inhibitor of Kv1.1, Kv1.3, and Kv1.6 channels, into the CMT awakened sevoflurane-anesthetized rodents. In heterologous expression systems, sevoflurane, isoflurane, and desflurane at subsurgical concentrations potentiated delayed rectifier Kv1 channels at low depolarizing potentials. In mouse thalamic brain slices, sevoflurane inhibited firing frequency and delayed the onset of action potentials in CMT neurons, and ShK-186, a Kv1.3-selective inhibitor, prevented these effects. Our findings demonstrate the exquisite sensitivity of delayed rectifier Kv1 channels to modulation by volatile anesthetics and highlight an arousal suppressing role of Kv1 channels in CMT neurons during the process of anesthesia. PMID:24107962

  4. Mid-crustal deformation of the Annapurna-Dhaulagiri Himalaya, central Nepal: An atypical example of channel flow during the Himalayan orogeny

    OpenAIRE

    2016-01-01

    The channel-flow model for the Greater Himalayan Sequence (GHS) of the Himalayan orogen involves a partially molten, rheologically weak, mid-crustal layer “flowing” southward relative to the upper and lower crust during late Oligocene–Miocene. Flow was driven by topographic overburden, underthrusting, and focused erosion. We present new structural and thermobarometric analyses from the GHS in the Annapurna-Dhaulagiri Hima­laya, central Nepal; these data suggest that during exhumation, the GHS...

  5. Nitric oxide and L-type calcium channel influences the changes in arterial blood pressure and heart rate induced by central angiotesin II

    Directory of Open Access Journals (Sweden)

    Guarda Ismael FMS

    2008-05-01

    Full Text Available Abstract We study the voltage dependent calcium channels and nitric oxide involvement in angiotensin II-induced pressor effect. The antipressor action of L-Type calcium channel antagonist, nifedipine, has been studied when it was injected into the third ventricle prior to angiotensin II. The influence of nitric oxide on nifedipine antipressor action has also been studied by utilizing NW-nitro-L-arginine methyl ester (LNAME (40 μg/0.2 μl a nitric oxide synthase inhibitor and L-arginine (20 μg/0.2 μl, a nitric oxide donor agent. Adult male Holtzman rats weighting 200–250 g, with cannulae implanted into the third ventricle were injected with angiotensin II. Angiotensin II produced an elevation in mean arterial pressure and a decreased in heart rate. Such effects were potentiated by the prior injection of LNAME. L-arginine and nifedipine blocked the effects of angiotensin II. These data showed the involvement of L-Type calcium channel and a free radical gas nitric oxide in the central control of angiotensin II-induced pressor effect. This suggested that L-Type calcium channel of the circunventricular structures of central nervous system participated in both short and long term neuronal actions of ANG II with the influence of nitrergic system.

  6. Mutations in voltage-gated potassium channel KCNC3 cause degenerative and developmental central nervous system phenotypes.

    Science.gov (United States)

    Waters, Michael F; Minassian, Natali A; Stevanin, Giovanni; Figueroa, Karla P; Bannister, John P A; Nolte, Dagmar; Mock, Allan F; Evidente, Virgilio Gerald H; Fee, Dominic B; Müller, Ulrich; Dürr, Alexandra; Brice, Alexis; Papazian, Diane M; Pulst, Stefan M

    2006-04-01

    Potassium channel mutations have been described in episodic neurological diseases. We report that K+ channel mutations cause disease phenotypes with neurodevelopmental and neurodegenerative features. In a Filipino adult-onset ataxia pedigree, the causative gene maps to 19q13, overlapping the SCA13 disease locus described in a French pedigree with childhood-onset ataxia and cognitive delay. This region contains KCNC3 (also known as Kv3.3), encoding a voltage-gated Shaw channel with enriched cerebellar expression. Sequencing revealed two missense mutations, both of which alter KCNC3 function in Xenopus laevis expression systems. KCNC3(R420H), located in the voltage-sensing domain, had no channel activity when expressed alone and had a dominant-negative effect when co-expressed with the wild-type channel. KCNC3(F448L) shifted the activation curve in the negative direction and slowed channel closing. Thus, KCNC3(R420H) and KCNC3(F448L) are expected to change the output characteristics of fast-spiking cerebellar neurons, in which KCNC channels confer capacity for high-frequency firing. Our results establish a role for KCNC3 in phenotypes ranging from developmental disorders to adult-onset neurodegeneration and suggest voltage-gated K+ channels as candidates for additional neurodegenerative diseases.

  7. Effects of in vitro and in vivo lead exposure on voltage-dependent calcium channels in central neurons of Lymnaea stagnalis.

    Science.gov (United States)

    Audesirk, G

    1987-01-01

    Currents through calcium channels of members of an identified cluster of neurons (B cells) in the pond snail Lymnaea stagnalis were studied under voltage clamp. The normal physiological saline was modified to maximize the visibility of voltage-dependent calcium currents and minimize contamination by other currents. Barium was used as the charge carrier for the calcium channels. Depolarizing voltage steps induce an inward current, the magnitude of which varies with the barium concentration. In brains taken from animals not exposed in vivo to lead, in vitro addition of lead acetate to the recording medium (0.25 to 14 microM) inhibits the barium current by 59 +/- 14% (mean +/- s.d.), in a manner that is independent of the lead concentration. The magnitude of the residual current still varies with the barium concentration. The voltage dependence of the current appears to be unaffected by lead. In contrast to some other calcium-channel blockers, such as cobalt, the inhibition of barium currents by in vitro lead exposure is irreversible, at least in short-term experiments. Contrary to expectations based on these in vitro results, barium currents in B cells of animals exposed to 5 microM lead for 6 to 12 weeks in vivo were approximately twice as large as barium currents in B cells from unexposed controls, when both were recorded in lead-free saline. It is possible that chronic in vivo lead exposure causes an increase in the number of calcium channels in these neurons.

  8. Effects of in vitro lead exposure on voltage-sensitive calcium channels differ among cell types in central neurons of Lymnaea stagnalis.

    Science.gov (United States)

    Audesirk, G; Audesirk, T

    1989-01-01

    The effects of acute in vitro lead exposure on slowly inactivating voltage-sensitive calcium channels in central neurons of the freshwater pond snail Lymnaea stagnalis were studied under voltage clamp. Three physiologically distinct cell types were used: two subsets of the B cell cluster (Bpos and Bneg) and the pedal giant neuron (RPeD1). In Bpos neurons, 5 nM free Pb2+ irreversibly inhibited current flow through calcium channels by 38 +/- 10%. In Bneg neurons, 5 nM free Pb2+ slightly inhibited inward currents (12 +/- 6%) and may have shifted their voltage dependence to more depolarized voltages. The inhibition and voltage shift were irreversible. In RPeD1 neurons, Pb2+ caused a small, statistically insignificant inhibition of inward current (5 nM free Pb2+; 18 +/- 19%; 30 nM free Pb2+: 31 +/- 23%). The effects of Pb2+ were fully reversible. These data indicate that (1) voltage-sensitive calcium channels in Lymnaea neurons are inhibited by nanomolar concentrations of free Pb2+; (2) there are multiple types of calcium channels in Lymnaea neurons; and (3) the effects of in vitro lead exposure differ qualitatively among channel types.

  9. The emergence of insecticide resistance in central Mozambique and potential threat to the successful indoor residual spraying malaria control programme

    Directory of Open Access Journals (Sweden)

    Wilding Craig S

    2011-05-01

    Full Text Available Abstract Background Malaria vector control by indoor residual spraying was reinitiated in 2006 with DDT in Zambézia province, Mozambique. In 2007, these efforts were strengthened by the President's Malaria Initiative. This manuscript reports on the monitoring and evaluation of this programme as carried out by the Malaria Decision Support Project. Methods Mosquitoes were captured daily through a series of 114 window exit traps located at 19 sentinel sites, identified to species and analysed for sporozoites. Anopheles mosquitoes were collected resting indoors and tested for insecticide resistance following the standard WHO protocol. Annual cross sectional household parasite surveys were carried out to monitor the impact of the control programme on prevalence of Plasmodium falciparum in children aged 1 to 15 years. Results A total of 3,769 and 2,853 Anopheles gambiae s.l. and Anopheles funestus, respectively, were captured from window exit traps throughout the period. In 2010 resistance to the pyrethroids lambda-cyhalothrin and permethrin and the carbamate, bendiocarb was detected in An. funestus. In 2006, the sporozoite rate in An. gambiae s.s. was 4% and this reduced to 1% over 4 rounds of spraying. The sporozoite rate for An. funestus was also reduced from 2% to 0 by 2008. Of the 437 Anopheles arabiensis identified, none were infectious. Overall prevalence of P. falciparum in the sentinel sites fell from 60% to 32% between October 2006 and October 2008. Conclusion Both An. gambiae s.s. and An. funestus were controlled effectively with the DDT-based IRS programme in Zambézia, reducing disease transmission and burden. However, the discovery of pyrethroid resistance in the province and Mozambique's policy change away from DDT to pyrethroids for IRS threatens the gains made here.

  10. Pertussis toxin modulation of sodium channels in the central neurons of cyhalothrin-resistant and cyhalothrin-susceptible cotton bollworm, Helicoverpa armigera

    Institute of Scientific and Technical Information of China (English)

    QIANG ZHAO; DE-LING KONG; BING-JUN HE; YAN-QIANG LIU; XIAN-LIN FAN; AN-XI LIU

    2007-01-01

    Pertussis toxin (PTX) inhibits the activation of the α-subunit of the inhibitory heterotrimeric G-proteins (Gαi/o) and modulates voltage-gated sodium channels, which may be one of the primary targets of pyrethroids. To investigate the potential mechanisms of agricultural pests resistance to pyrethroid insecticides, we examined the modulations by PTX on sodium channels in the central neurons of the 3rd-4th instar larvae of cyhalothrin-resistant (Cy-R) and cyhalothrin-susceptible (Cy-S) Helicoverpa armigera by the whole-cell patch-clamp technique.The isolated neurons were cultured for 12-16 h in an improved L15 insect culture medium with or without PTX (400 ng/mL). The results showed that both the Cy-R and Cy-S sodium channels exhibited fast kinetics and tetrodotoxin (TTX) sensitivity. The Cy-R sodium channels exhibited not only altered gating properties, including a 8.88-mV right shift in voltage-dependent activation (V0.5act) and a 6.54-mV right shift in voltage-dependent inactivation (V0.5inact), but also a reduced peak in sodium channel density (Idensity) (55.2% of that in Cy-S neurons). Cy-R sodium channels also showed low excitability, as evidenced by right shift of activation potential (Vacti) by 5-10 mV and peak potential (Vpeak) by 20 mV. PTX exerted significant effects on Cy-S sodium channels,reducing sodium channel density by 70.04%, right shifting V0.5act by 14.41 mV and V0.5inact by 9.38 mV. It did not cause any significant changes of the parameters mentioned above in the Cy-R sodium channels. The activation time (Tpeak) from latency to peak at peak voltage and the fast inactivation time constant (τinact) in both Cy-S and Cy-R neurons were not affected. The results suggest that cotton bollworm resistant to pyrethroid insecticides involves not only mutations and allosteric alterations of voltage-gated sodium channels, but also might implicate perturbation of PTX-sensitive Gαi/o-coupled signaling transduction pathways.

  11. Life cycle assessment of post-consumer plastics production from waste electrical and electronic equipment (WEEE) treatment residues in a Central European plastics recycling plant.

    Science.gov (United States)

    Wäger, Patrick A; Hischier, Roland

    2015-10-01

    Plastics play an increasingly important role in reaching the recovery and recycling rates defined in the European WEEE Directive. In a recent study we have determined the life cycle environmental impacts of post-consumer plastics production from mixed, plastics-rich WEEE treatment residues in the Central European plant of a market-leading plastics recycler, both from the perspective of the customers delivering the residues and the customers buying the obtained post-consumer recycled plastics. The results of our life cycle assessments, which were extensively tested with sensitivity analyses, show that from both perspectives plastics recycling is clearly superior to the alternatives considered in this study (i.e. municipal solid waste incineration (MSWI) and virgin plastics production). For the three ReCiPe endpoint damage categories, incineration in an MSWI plant results in an impact exceeding that of the examined plastics recycling facility each by about a factor of 4, and the production of virgin plastics has an impact exceeding that of the post-consumer recycled (PCR) plastics production each by a factor of 6-10. On a midpoint indicator level the picture is more differentiated, showing that the environmental impacts of the recycling options are lower by 50% and more for almost all impact factors. While this provides the necessary evidence for the environmental benefits of plastics recycling compared to existing alternatives, it can, however, not be taken as conclusive evidence. To be conclusive, future research will have to address the fate of hazardous substances in the outputs of such recycling systems in more detail.

  12. Romania's experience in using woody residues as a combustible for central heating; L'experience roumaine de l'utilisation des residus ligneux comme combustible pour le chauffage central

    Energy Technology Data Exchange (ETDEWEB)

    Lavrov, G. [Inst. des Etudes et des Projets Energetiques (Romania)

    2004-06-01

    Romania's national policy for renewable resources promotes the use of clean and renewable energy. The national policy is intended to increase the national contribution of renewable energy sources and to develop non-conventional technologies for exploiting renewable resources. This paper described two examples where woody residues are used as a combustible for central heating. The first example describes a local industry in Campeni, a village of 10,000 people located near the Aires River, which produces 54,000 tons of ligneous waste each year. A central heating plant was modernized to accept this waste as a fuel. Two old boilers were replaced with two modern, Romanian-made boilers that produce a calorific output of 8,790 kJ/kg. The efficiency of the new boilers is 83 per cent. The benefits of this modernization have been a significant reduction in pollution of the Aires River by reducing the number of ligneous waste dumped into the river. Carbon dioxide and SOx emissions have also been reduced by replacing fossil fuel with biomass. The thermal comfort of the buildings served by the heating plant has also improved because the new boilers produce 88 per cent more heat. The second example focuses on the village of Tasca in Moldavia, a forest rich region of Romania where the wood dust from local saw mills has polluted the Bicaz and Damuc Rivers. A project was launched to develop an urban district heating system by installing a new 2.5 MW boiler fueled by sawdust and ligneous waste. Consumers were connected to the thermal energy distribution system. A separate system was created to collect waste from the sawmills. The benefits of this project have been a significant reduction in the pollution of the rivers, increased comfort levels in houses and a significant reduction in air pollution because the old individual and inefficient heating systems were replaced with an efficient central heating system. 1 tab.

  13. Management of distortion channels in the Cofrentes NPP; Gestion de la deformacion de canales en la central nuclear de Cofrentes

    Energy Technology Data Exchange (ETDEWEB)

    Albendea, J. C.; Garcia, P. J.; Iglesias, J.; Mascarell, R.

    2015-07-01

    Fuel channels distortion in BWR (Boiling Water Reactor) reactors may have implication for safety. This phenomenon is complex and, at the present time it is not known in detail. This article provides the Iberdrola Generacion Nuclear SAU ongoing activities to know, predict and mitigate the consequences that this phenomenon may cause in Cofrentes Nuclear Power Plant. (Author)

  14. Molecular dissection of the contribution of negatively and positively charged residues in S2, S3, and S4 to the final membrane topology of the voltage sensor in the K+ channel, KAT1.

    Science.gov (United States)

    Sato, Yoko; Sakaguchi, Masao; Goshima, Shinobu; Nakamura, Tatsunosuke; Uozumi, Nobuyuki

    2003-04-11

    Voltage-dependent ion channels control changes in ion permeability in response to membrane potential changes. The voltage sensor in channel proteins consists of the highly positively charged segment, S4, and the negatively charged segments, S2 and S3. The process involved in the integration of the protein into the membrane remains to be elucidated. In this study, we used in vitro translation and translocation experiments to evaluate interactions between residues in the voltage sensor of a hyperpolarization-activated potassium channel, KAT1, and their effect on the final topology in the endoplasmic reticulum (ER) membrane. A D95V mutation in S2 showed less S3-S4 integration into the membrane, whereas a D105V mutation allowed S4 to be released into the ER lumen. These results indicate that Asp(95) assists in the membrane insertion of S3-S4 and that Asp(105) helps in preventing S4 from being releasing into the ER lumen. The charge reversal mutation, R171D, in S4 rescued the D105R mutation and prevented S4 release into the ER lumen. A series of constructs containing different C-terminal truncations of S4 showed that Arg(174) was required for correct integration of S3 and S4 into the membrane. Interactions between Asp(105) and Arg(171) and between negative residues in S2 or S3 and Arg(174) may be formed transiently during membrane integration. These data clarify the role of charged residues in S2, S3, and S4 and identify posttranslational electrostatic interactions between charged residues that are required to achieve the correct voltage sensor topology in the ER membrane.

  15. Extracellular acid block and acid-enhanced inactivation of the Ca2+-activated cation channel TRPM5 involve residues in the S3-S4 and S5-S6 extracellular domains.

    Science.gov (United States)

    Liu, Dan; Zhang, Zheng; Liman, Emily R

    2005-05-27

    TRPM5, a member of the superfamily of transient receptor potential ion channels, is essential for the detection of bitter, sweet, and amino acid tastes. In heterologous cell types it forms a nonselective cation channel that is activated by intracellular Ca(2+). TRPM5 is likely to be part of the taste transduction cascade, and regulators of TRPM5 are likely to affect taste sensation. In this report we show that TRPM5, but not the related channel TRPM4b, is potently blocked by extracellular acidification. External acidification has two effects, a fast reversible block of the current (IC(50) pH = 6.2) and a slower irreversible enhancement of current inactivation. Mutation of a single Glu residue in the S3-S4 linker and a His residue in the pore region each reduced sensitivity of TRPM5 currents to fast acid block (IC(50) pH = 5.8 for both), and the double mutant was nearly insensitive to acidic pH (IC(50) pH = 5.0). Prolonged exposure to acidic pH enhanced inactivation of TRPM5 currents, and mutant channels that were less sensitive to acid block were also less sensitive to acid-enhanced inactivation, suggesting an intimate association between the two processes. These processes are, however, distinct because the pore mutant H896N, which has normal sensitivity to acid block, shows significant recovery from acid-enhanced inactivation. These data show that extracellular acidification acts through specific residues on TRPM5 to block conduction through two distinct but related mechanisms and suggest a possible interaction between extracellular pH and activation and adaptation of bitter, sweet, and amino acid taste transduction.

  16. Conservation analysis of residues in the S4-S5 linker and the terminal part of the S5-P-S6 pore modulus in Kv and HCN channels: flexible determinants for the electromechanical coupling.

    Science.gov (United States)

    Balleza, Daniel; Carrillo, Elisa; Gómez-Lagunas, Froylán

    2015-10-01

    Protein mobility is important to achieve protein function. Intrinsic flexibility associated with motion underlies this important issue and the analysis of side chain flexibility gives insights to understand it. In this work, the S5-P-S6 pore modulus (PM) of members of Kv and HCN channels was examined by a combination of sequence alignment, residue composition analysis, and intrinsic side chain flexibility. The PM sequences were organized as a database that was used to reveal and correlate the functional diversity of each analyzed family. Specifically, we focused our attention on the crucial role of the S4-S5 linker and its well-described interaction with the S6 T during the electromechanical coupling. Our analysis suggests the presence of a Gly-hinge in the middle of the S4-S5 linkers. This apparent Gly-hinge links a flexible N-terminal segment with a rigid C-terminal one, although in Kv7 channels, the latter segment is even more flexible. Instead, HCN channels exhibit a putative Thr-hinge and is rich in aromatic residues, in consequence, their linker is more rigid. Concerning S6, we confirm the presence of the two flexible kinks previously described and we provide the complete segmental flexibility profiles for the different families. Our results are discussed in terms of the relation between residue composition, conservation, and local conformational flexibility. This provides important insights to understand and differentiate the characteristic gating properties of these channels as well as their implications in cell physiology.

  17. Polycyclic Aromatic Hydrocarbons Residues in Gentile Di Maiale, a Smoked Meat Product Typical of Some Mountain Areas in Latina Province (Central Italy)

    Science.gov (United States)

    Carrabs, Giuseppe; Mercogliano, Raffaelina; Carosielli, Leonardo; Vollano, Lucia; Anastasio, Aniello

    2014-01-01

    Gentile di maiale is a typical meat product prepared in some traditional plants of Latina Province (Central Italy). It is obtained from dehydration, salting, smoking and ripening of swine rectum. Aim of this study was to evaluate the influence of the traditional smoking process on polycyclic aromatic hydrocarbons (PAHs) content by means of high-performance liquid chromatographic/fluorescence detection. Polycyclic aromatic hydrocarbons detected in 8 samples of raw material (swine rectum) and samples of smoked gentile were: benzo[a]anthracene, chrisene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a] pyrene, benzo[a,h]anthracene. Their residues were detected in all samples of finished product. European Regulation 835/2011 established two levels of PAHs content in meat products. According to first levels, in force until September 2014, only 2 out of 8 samples exceeded legal limit. According to the subsequent, more restrictive, limits all samples would be non-compliant. An improvement and a standardisation of traditional smoking procedures are recommended.

  18. Polycyclic aromatic hydrocarbons residues in Gentile di maiale, a smoked meat product typical of some mountain areas in Latina province (Central Italy

    Directory of Open Access Journals (Sweden)

    Giuseppe Carrabs

    2014-05-01

    Full Text Available Gentile di maiale is a typical meat product prepared in some traditional plants of Latina Province (Central Italy. It is obtained from dehydration, salting, smoking and ripening of swine rectum. Aim of this study was to evaluate the influence of the traditional smoking process on polycyclic aromatic hydrocarbons (PAHs content by means of high-performance liquid chromatographic/fluorescence detection. Polycyclic aromatic hydrocarbons detected in 8 samples of raw material (swine rectum and samples of smoked gentile were: benzo[a]anthracene, chrisene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a] pyrene, benzo[a,h]anthracene. Their residues were detected in all samples of finished product. European Regulation 835/2011 established two levels of PAHs content in meat products. According to first levels, in force until September 2014, only 2 out of 8 samples exceeded legal limit. According to the subsequent, more restrictive, limits all samples would be non-compliant. An improvement and a standardisation of traditional smoking procedures are recommended.

  19. Erosion and deposition by supercritical density flows during channel avulsion and backfilling: Field examples from coarse-grained deepwater channel-levée complexes (Sandino Forearc Basin, southern Central America)

    Science.gov (United States)

    Lang, Jörg; Brandes, Christian; Winsemann, Jutta

    2017-03-01

    Erosion and deposition by supercritical density flows can strongly impact the facies distribution and architecture of submarine fans. Field examples from coarse-grained channel-levée complexes from the Sandino Forearc Basin (southern Central America) show that cyclic-step and antidune deposits represent common sedimentary facies of these depositional systems and relate to the different stages of avulsion, bypass, levée construction and channel backfilling. During channel avulsion, large-scale scour-fill complexes (18 to 29 m deep, 18 to 25 m wide, 60 to > 120 m long) were incised by supercritical density flows. The multi-storey infill of the large-scale scour-fill complexes comprises amalgamated massive, normally coarse-tail graded or widely spaced subhorizontally stratified conglomerates and pebbly sandstones, interpreted as deposits of the hydraulic-jump zone of cyclic steps. The large-scale scour-fill complexes can be distinguished from small-scale channel fills based on the preservation of a steep upper margin and a coarse-grained infill comprising mainly amalgamated hydraulic-jump zone deposits. Channel fills include repeated successions deposited by cyclic steps with superimposed antidunes. The deposits of the hydraulic-jump zone of cyclic steps comprise regularly spaced scours (0.2 to 2.6 m deep, 0.8 to 23 m long) infilled by intraclast-rich conglomerates or pebbly sandstones, displaying normal coarse-tail grading or backsets. These deposits are laterally and vertically associated with subhorizontally stratified, low-angle cross-stratified or sinusoidally stratified sandstones and pebbly sandstones, which were deposited by antidunes on the stoss side of the cyclic steps during flow re-acceleration. The field examples indicate that so-called spaced stratified deposits may commonly represent antidune deposits with varying stratification styles controlled by the aggradation rate, grain-size distribution and amalgamation. The deposits of small-scale cyclic

  20. Long-term fluid expulsion revealed by carbonate crusts and pockmarks connected to subsurface gas anomalies and palaeo-channels in the central North Sea

    Science.gov (United States)

    Chand, Shyam; Crémière, Antoine; Lepland, Aivo; Thorsnes, Terje; Brunstad, Harald; Stoddart, Daniel

    2016-11-01

    Gas seepage through the seafloor into the water column is inferred based on acoustic mapping, video observations and geochemical analyses at multiple locations in the Viking Graben and Utsira High areas of the central North Sea. Flares in the Viking Graben occur both inside and along the periphery of a submarine melt water channel where pockmarks (up to 500 m in diameter) and methane-derived carbonate crusts are found on the seafloor, indicating focussing of fluid flow in the vicinity of the channel. The flares can be related to gas accumulations close to the seafloor as well as in Quaternary and deeper strata, observed as high-amplitude reflections on seismic data. Many palaeo-channels, which act as accumulation zones, are observed in the subsurface of both the Viking Graben and Utsira High areas. The deeper origin of gas is partially supported by results of isotope analyses of headspace gas collected from sediment samples of the Viking Graben, which show a mixed microbial/thermogenic origin whereas isotope data on free seeping gas in the Viking Graben indicate a predominantly microbial origin. Based on these lines of evidence, a structure-controlled fluid flow model is proposed whereby hydrocarbons migrate in limited amount from deep thermogenic reservoirs along faults, and these deep fluids are strongly diluted by microbial methane. Moreover, the existence of subsurface pockmarks at several stratigraphic levels indicates long-term fluid flow, interpreted to be caused by gas hydrate destabilisation and stress-related high overpressures.

  1. Spatial and temporal variability of the sea surface temperature in the Ballenas-Salsipuedes Channel (central Gulf of California)

    Science.gov (United States)

    MartíNez-DíAz-De-León, A.; Pacheco-RuíZ, I.; Delgadillo-Hinojosa, F.; Zertuche-GonzáLez, J. A.; Chee-BarragáN, A.; Blanco-Betancourt, R.; GuzmáN-Calderón, J. M.; GáLvez-Telles, A.

    2006-02-01

    The Ballenas-Salsipuedes Channel (BSC) is considered an oceanographic province on its own within the Gulf of California. In this region, tidal mixing is modulated by quarterdiurnal, semidiurnal, diurnal, and fortnightly frequencies, producing a strong outcropping of cold and nutrient-rich waters. In this work we analyze the temporal and spatial variability of sea surface temperature (SST) data recorded simultaneously over a period of 1 year in six bays along the BSC. Minimum mean SST differences ( 2.5°C) were recorded in June. The monthly SST anomaly showed that from late October to late January, the channel behaved as a very well mixed region. In contrast, SST anomalies of up to 2.2°C among bays were observed from May to September, indicating intense heat gain in summer and highlighting spatial heterogeneity in the intensity of vertical mixing. Besides the seasonal temperature cycle, influenced by solar irradiation, four main periods (0.25, 0.5, 1, and 15 days) were identified, corresponding to the main timescales of variability induced by the tides. This work demonstrates that the main source of temporal SST variability in BSC is the tide-induced fortnightly modulation, suggesting the possibility of a pulsation mechanism in the outcropping of nutrient-rich waters reaching the surface layer throughout the channel; this could play a crucial role in explaining the exceptionally high biological production of this region.

  2. Single-channel analysis of a point mutation of a conserved serine residue in the S2 ligand-binding domain of the NR2A NMDA receptor subunit.

    Science.gov (United States)

    Wyllie, David J A; Johnston, Alexander R; Lipscombe, Diane; Chen, Philip E

    2006-07-15

    We have examined the function of a conserved serine residue (Ser670) in the S2 ligand-binding region of the NR2A N-methyl-d-aspartate (NMDA) receptor subunit, using recombinant NR1/NR2A receptors expressed in Xenopus laevis oocytes. Mutation of Ser670 to glycine (S670G) in NR2A reduced the potency of glutamate by 124-fold. Single-channel conductance and the duration of apparent open periods of NR2A(S670G) receptor mutants were, however, indistinguishable from wild-type NMDA receptors. NR1/NR2A(S670G) shut-time distributions were best described by a mixture of six exponential components, and the four shortest shut intervals of each distribution were considered to occur within a channel activation (burst). Bursts of single-channel openings were fitted with a mixture of four exponential components. The longest two components carried the majority of the charge transfer and had mean durations of 9.6 +/- 0.5 and 29.6 +/- 1.5 ms. The overall channel open probability during a burst was high (mean, 0.83 +/- 0.06). Consistent with a shortening of NMDA receptor-channel burst lengths was the observation of an increased deactivation rate of macroscopic currents evoked by brief applications of glutamate to outside-out membrane patches. Correlations between shut times and adjacent open times were observed in all data records. Noticeably, shorter than average openings tended to occur next to long closed periods, whereas longer than average openings tended to occur next to short closings. Our single-channel data, together with modelling using a kinetic scheme to describe channel activations, support our hypothesis that the S670G point mutation reduces the dwell time of glutamate in its binding site.

  3. A study of the $\\eta\\eta$ channel produced in central pp interactions at 450 GeV/c

    CERN Document Server

    Barberis, D; Close, Francis Edwin; Danielsen, K M; Donskov, S V; Earl, B C; Evans, D; French, Bernard R; Hino, T; Inaba, S; Jacholkowski, A; Jacobsen, T; Khaustov, G V; Kinson, J B; Kirk, A; Kondashov, A A; Lednev, A A; Lenti, V; Minashvili, I A; Peigneux, J P; Romanovsky, V I; Rusakovitch, N A; Semenov, A A; Shagin, P M; Shimizu, H; Singovsky, A V; Sobol, A E; Stassinaki, M; Stroot, Jean-Pierre; Takamatsu, K; Tsuru, T; Villalobos Baillie, O; Votruba, M F; Yasu, Y

    2000-01-01

    The reaction pp -> pf (eta eta) ps has been studied at 450 GeV/c. For the first time a partial wave analysis of the centrally produced eta eta system has been performed. Signals for the f0(1500), f0(1710) and f2(2150) are observed and the decay branching fractions of these states are determined.

  4. Towards an integrated assessment of the impacts of forest residue mulching following wildfire in eucalypt plantations in north-central Portugal

    Science.gov (United States)

    Keizer, Jan Jacob; Abrantes, Nelson; Bastos, Ana; Brandsma, Micha; Campos, Isabel; Faria, Silvia; Malvar, Maruxa; Martins, Martinho; João Oliveira, Maria; Pimpão, Gabriel; Prats, Sergio; Puga, João; Ribeiro, Cristina; Rocha, João; Santos, Liliana; Serpa, Dalila; Silva, Flávio; Silva, Tiago; Valente, Sandra; Vieira, Diana

    2016-04-01

    In the framework of the EU-FP7 project RECARE (www.recare-project.eu) and, in particular, its WP6, the University of Aveiro partner has recently started testing two measures against the soil threat of post-fire erosion by water in an area in north-central Portugal, close to Coimbra that burnt during the summer of 2015. These measures - mulching with forest slash residues and contour ploughing - had been selected by the local and external stakeholders involved in the project, through two subsequent stakeholder workshops. While contour ploughing has still not taken place, the mulching was already carried out, using residues from eucalypt plantations as the burnt areas was dominated by eucalypt plantations, and applying them in a homogeneous fashion at two contrasting application rates, i.e. a "standard" rate of approximately 10 Mg ha-1 and a "reduced" rate of about 3 Mg ha-1. The standard rate was selected for having proved effective in reducing post-fire runoff and erosion in previous field studies in the region (Prats et al., 2012, 2014, 2015a), while the reduced rate had been found to be nearly as effective as the standard rate in a recent study in the hydraulic laboratory of the University of Coimbra (Prats et al., 2015b). Unlike the referred prior studies, however, the present study will also assess the impacts of mulching on two other soil threats - i.e. decline in soil organic matter and in soil biodiversity - and, ultimately, will compare the two measures in terms of their consequences for soil-based ecosystem services, using the framework being developed by RECARE (Schwilch et al. in Stolte et al., 2016). The proposed presentation will show the first results on the effects of the two mulch application rates on post-fire runoff as well as the associated losses of sediments, organic matter/C and nutrients (N, P), and on selected indicators of soil biological activity and diversity. Prats et al., 2015a (in press). LD&D (doi: 10.1002/ldr.2422) Prats et al., 2015

  5. Lack of negatively charged residues at the external mouth of Kir2.2 channels enable the voltage-dependent block by external Mg2+.

    Directory of Open Access Journals (Sweden)

    Junwei Li

    Full Text Available Kir channels display voltage-dependent block by cytosolic cations such as Mg2+ and polyamines that causes inward rectification. In fact, cations can regulate K channel activity from both the extracellular and intracellular sides. Previous studies have provided insight into the up-regulation of Kir channel activity by extracellular K+ concentration. In contrast, extracellular Mg2+ has been found to reduce the amplitude of the single-channel current at milimolar concentrations. However, little is known about the molecular mechanism of Kir channel blockade by external Mg2+ and the relationship between the Mg2+ blockade and activity potentiation by permeant K+ ions. In this study, we applied an interactive approach between theory and experiment. Electrophysiological recordings on Kir2.2 and its mutants were performed by heterologous expression in Xenopus laevis oocytes. Our results confirmed that extracellular Mg2+ could reduce heterologously expressed WT Kir2.2 currents in a voltage dependent manner. The kinetics of inhibition and recovery of Mg2+ exhibit a 3∼4s time constant. Molecular dynamics simulation results revealed a Mg2+ binding site located at the extracellular mouth of Kir2.2 that showed voltage-dependent Mg2+ binding. The mutants, G119D, Q126E and H128D, increased the number of permeant K+ ions and reduced the voltage-dependent blockade of Kir2.2 by extracellular Mg2+.

  6. Physico-chemical properties of cloud drop residual and interstitial particles sampled inside hill capped clouds during a field experiment in Central Europe

    Science.gov (United States)

    Mertes, S.; Schneider, J.; Merkel, M.; Roth, A.; Van Pinxteren, D.; Wiedensohler, A.; Herrmann, H.

    2011-12-01

    Aerosol-cloud interaction, particle activation and phase partitioning of ambient aerosol particles between the liquid and interstitial phase in continental boundary layer clouds were investigated during the Hill Cap Cloud Thuringia field experiment in autumn 2010 (HCCT 2010). An interstitial inlet (INT) and two counterflow virtual impactors (CVI) were operated inside cloud in order to separate and collect non-activated interstitial particles (IP) and cloud drops, respectively, on the mountain site Schmücke (938 m asl) in Central Europe. Both inlet types were designed for a separation diameter of 5 μm. Inside the CVI systems the collected drops are evaporated releasing dry cloud drop residues (CDR), which are closely related to the original cloud condensation nuclei forming the cloud. By two sets of instruments that measured the same parameter connected to each inlet type, the CDR and IP were micro-physically and chemically characterized simultaneously. Number concentration and size distribution were determined by a condensation particle counter (CPC) and scanning mobility particle sizer (SMPS) + optical particle counter (OPC) at INT and CVI. The chemical composition of CDR and IP was inferred in various ways. The amount of black carbon in each reservoir was measured by two particle soot absorption photometers (PSAP) supplemented by a multiangle absorption photometer (MAAP) at the interstitial inlet only. The content of non-refractory chemical compounds was analyzed by a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) and a high-resolution (HR)-ToF- AMS for the CDR and IP, respectively. Filter and adsorption cartridge samples were taken at both inlet types to determine selected inorganic and organic species. The mixing state of single cloud drop residues was derived from the aircraft-based laser ablation aerosol mass spectrometer ALABAMA. During the analyzed cloud events, the cloud microphysical parameters measured by a particle volume monitor (PVM

  7. The human ether-a'-go-go related gene (hERG) K+ channel blockade by the investigative selective-serotonin reuptake inhibitor CONA-437: limited dependence on S6 aromatic residues.

    Science.gov (United States)

    Alexandrou, A J; Milnes, J T; Sun, S Z; Fermini, B; Kim, S C; Jenkinson, S; Leishman, D J; Witchel, H J; Hancox, J C; Leaney, J L

    2014-08-01

    Diverse non-cardiac drugs adversely influence cardiac electrophysiology by inhibiting repolarising K(+) currents mediated by channels encoded by the human ether-a-go-go-related gene (hERG). In this study, pharmacological blockade of hERG K(+) channel current (I(hERG)) by a novel investigative serotonin-selective reuptake inhibitor (SSRI), CONA-437, was investigated. Whole-cell patch-clamp measurements of I(hERG) were made from human embryonic kidney (HEK 293) cells expressing wild-type (WT) or mutant forms of the hERG channel. With a step-ramp voltage-command, peak I(hERG) was inhibited with an IC(50) of 1.34 μM at 35 ±1°C; the IC(50) with the same protocol was not significantly different at room temperature. Voltage-command waveform selection had only a modest effect on the potency of I(hERG) block: the IC50 with a ventricular action potential command was 0.72 μM. I(hERG) blockade developed rapidly with time following membrane depolarisation and showed a weak dependence on voltage, accompanied by a shift of ≈ -5 mV in voltage-dependence of activation. There was no significant effect of CONA-437 on voltage-dependence of I(hERG) inactivation, though at some voltages an apparent acceleration of the time-course of inactivation was observed. Significantly, mutation of the S6 aromatic amino acid residues Y652 and F656 had only a modest effect on I(hERG) blockade by CONA-437 (a 3-4 fold shift in affinity). CONA-437 at up to 30 μM had no significant effect on either Nav1.5 sodium channels or L-type calcium channels. In conclusion, the novel SSRI CONA-437 is particularly notable as a gating-dependent hERG channel inhibitor for which neither S6 aromatic amino-acid constituent of the canonical drug binding site on the hERG channel appears obligatory for I(hERG) inhibition to occur.

  8. Kriging of Eocene sand channels from depth-averaged overburden pH, Jewett lignite surface mine, east-central Texas

    Energy Technology Data Exchange (ETDEWEB)

    Altis, S.; Tilford, N.R. [Texas A and M Univ., College Station, TX (United States)

    1995-12-01

    Ordinary point kriging was used to map twenty-six vertically-averaged soil and oxidized overburden acidity values for a future mine block at the Jewett lignite mine, east-central Texas. The pH data were collected as part of a geochemical overburden characterization study to be used in post-mining reclamation decision-making. The authors used kriging, and its estimation standard error, to test the completeness of their data set and to indicate areas of need for additional closely spaced sampling. Because pH can be readily measured in the field, they chose it as the parameter of interest in the kriging. In general pH increased with depth; however, a more exciting result was that the trend and geometry of a major paleo-channel could be mapped from pH values because of the relatively higher acidity of the sand in the channel. Kriged maps were compared with manually-contoured and inverse-distance weighting interpolated maps, and found to be more easily interpretable. The kriging performed better because it allows of anisotropies in the data to be naturally included in the interpolation. Prior to the kriging, the data were studied to validate the assumptions involved in the modeling. The data are clean, well-behaved and statistically homogeneous, and the interpolation was successful even with sparse data. The knowledge of the location and morphology of the paleochannels is essential for the engineering aspects of the mining, and is useful in reclamation decision-making.

  9. Micro thermoelectric power plant with residual biomass in a rice industry - efficiency increase due to a technological alteration; Micro central termeletrica com biomassa residual em uma industria de arroz - aumento de eficiencia por alteracao da tenologia

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Ronaldo; Hoffmann, Rejane S.; Lagemann, Angela M.; Cremonese, Guilherme; Collazzo, Gabriela C. [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Dept. de Engenharia Quimica; Machado, Luis A. [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Dept. de Eletromecanica e Sistemas de Potencia; Mayer, Flavio D. [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Curso de Pos-Graduacao em Engenharia de Producao]. E-mail: f.mayer@mail.ufsm.br

    2006-07-01

    A thermal electric system was implanted at Sao Pedro do Sul, Rio Grande do Sul, BR, for electric power self production. The initial analysis confirm the economic viability of the project and his contribution for the environment, through elimination of residue deposits and mitigation of the 4612 tCO{sub 2} equivalent greenhouse gases. Besides, an emphasis must be given to the contribution of the electric power decentralized generation for the regional development.

  10. Organochlorine pesticides residues and PCBs in benthic organisms of the inner shelf of the São Sebastião Channel, São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Rosângela Gorni

    2004-06-01

    Full Text Available Thirty seven benthic samples of the inner shelf area of São Sebastião, Brazil, were collected between April 1994 and August 1998 and analysed for seventeen chlorinated pesticide residues and PCBs congeners. Pesticide residues and PCBs congeners levels were low (ng/g and predominantly found in the crustacean samples. DDE was the most frequently residue with a maximum of 9,7 ng/g followed by HCHs with maximum of 17,1ng/g. As for the PCBs, the heavier congeners predominate: CB 138,153,170, 180 and 183. Maximum total PCBs was 17,4 ug/g in a crab sample. Higher levels of PCBs are related to feeding habits and local inputs of raw sewage or land runoff. Although EPA and FDA (U.S.A below the guidelines for human consumption propose these levels, they do show that even in marine areas without intense agricultural or industrial activities these compounds are present at detectable levels.Trinta e sete amostras de bentos da área interna do Canal de São Sebastião, Brasil, foram coletadas entre Abril de 1994 e Agosto de 1998 e analisadas quanto aos níveis de resíduos de 17 pesticidas organoclorados os congêneres dos PCBs. Os níveis de resíduos de organoclorados e PCBs foram baixos( ng/g e encontrados com maior freqüência nas amostras de crustáceos. DDE foi o resíduo de pesticida encontrado com mais freqüência apresentado um máximo de 9,7 ng/g seguido dos isômeros de HCHs com um máximo de 17,1 ng/g. No caso dos PCBs os congêneres mais pesados foram os predominantes: CB 138, 153, 170, 180 e 183. O valor máximo de PCBs totais foi de 17,4 ug/g numa amostra de crustáceo. Níveis maiores de PCBs estão associados aos hábitos alimentares e introduções pontuais de esgotos e água de drenagem urbana. Apesar dos níveis observados estarem abaixo dos recomendados para consumo humano pela EPA e da FDA( U.S.A ,eles demonstram que mesmo em área marinhas costeiras sem agricultura intensiva ou atividades industriais de porte , estes compostos org

  11. Field-collected permethrin-resistant Aedes aegypti from central Thailand contain point mutations in the domain IIS6 of the sodium channel gene (KDR).

    Science.gov (United States)

    Srisawat, Raweewan; Komalamisra, Narumon; Apiwathnasorn, Chamnarn; Paeporn, Pungasem; Roytrakul, Sittiruk; Rongsriyam, Yupha; Eshita, Yuki

    2012-11-01

    One of the mechanisms responsible for pyrethroid resistance in mosquitoes is mutations in domain IIS6 of voltage-gated sodium channel gene (kdr). Aedes aegypti larvae were collected from the central provinces of Thailand (Bangkok, Prachin Buri and Ratchaburi) and colonized until they became adults. Partial fragment of kdr of permethrin-resistant mosquitoes were amplified by RT-PCR and sequenced. Among the four nucleotide mutations detected, two mutations resulted in two amino acid substitutions, S(TCC) 989 P(CCC) and V(GTA)1016 G(GGA). Among 94 permethrin-resistant mosquitoes, the SS genotype (SS/VV) was found to predominate (n = 74), followed by SR (SP/VG) (n = 15) and RR (PP/ GG) genotypes (n = 5), with the resistant allele frequency ranging from 0.03 to 0.17. As pyrethroid insecticides are currently being advocated for use in Thailand, investigations of pyrethroid resistance in other regions of the country are needed to prevent potential cross-resistance among different types of insecticides.

  12. Mathematical Verification for Transmission Performance of Centralized Lightwave WDM-RoF-PON with Quintuple Services Integrated in Each Wavelength Channel

    Directory of Open Access Journals (Sweden)

    Shuai Chen

    2015-01-01

    Full Text Available Wavelength-division-multiplexing passive-optical-network (WDM-PON has been recognized as a promising solution of the “last mile” access as well as multibroadband data services access for end users, and WDM-RoF-PON, which employs radio-over-fiber (RoF technique in WDM-PON, is even a more attractive approach for future broadband fiber and wireless access for its strong availability of centralized multiservices transmission operation and its transparency for bandwidth and signal modulation formats. As for multiservices development in WDM-RoF-PON, various system designs have been reported and verified via simulation or experiment till now, and the scheme with multiservices transmitted in each single wavelength channel is believed as the one that has the highest bandwidth efficiency; however, the corresponding mathematical verification is still hard to be found in state-of-the-art literature. In this paper, system design and data transmission performance of a quintuple services integrated WDM-RoF-PON which jointly employs carrier multiplexing and orthogonal modulation techniques, have been theoretically analyzed and verified in detail; moreover, the system design has been duplicated and verified experimentally and the theory system of such WDM-RoF-PON scheme has thus been formed.

  13. Pesticide residue concentration in soil following conventional and Low-Input Crop Management in a Mediterranean agro-ecosystem, in Central Greece

    Energy Technology Data Exchange (ETDEWEB)

    Karasali, Helen, E-mail: e.karassali@bpi.gr [Laboratory of Chemical Control of Pesticides, Department of Pesticides Control and Phytopharmacy, Benaki Phytopathological Institute, 8 St. Delta Street, Kifissia, 14561 Athens (Greece); Marousopoulou, Anna [Laboratory of Chemical Control of Pesticides, Department of Pesticides Control and Phytopharmacy, Benaki Phytopathological Institute, 8 St. Delta Street, Kifissia, 14561 Athens (Greece); Machera, Kyriaki, E-mail: k.machera@bpi.gr [Laboratory of Pesticides Toxicology, Department of Pesticides Control and Phytopharmacy, Benaki Phytopathological Institute, 8 St. Delta Street, Kifissia, 14561 Athens (Greece)

    2016-01-15

    The present study was focused on the comparative evaluation of pesticide residues, determined in soil samples from Kopaida region, Greece before and after the implementation of Low-Input Crop Management (LCM) protocols. LCM has been suggested as an environmental friendly plant protection approach to be applied on crops growing in vulnerable to pollution ecosystems, with special focus on the site specific problems. In the case of the specific pilot area, the vulnerability was mainly related to the pollution of water bodies from agrochemicals attributed to diffuse pollution primarily from herbicides and secondarily from insecticides. A total of sixty-six soil samples, were collected and analyzed during a three-year monitoring study and the results of the determined pesticide residues were considered for the impact evaluation of applied plant protection methodology. The LCM was developed and applied in the main crops growing in the pilot area i.e. cotton, maize and industrial tomato. Herbicides active ingredients such as ethalfluralin, trifluralin, pendimethalin, S-metolachlor and fluometuron were detected in most samples at various concentrations. Ethalfluralin, which was the active ingredient present in the majority of the samples ranged from 0.01 μg g{sup −1} to 0.26 μg g{sup −1} soil dry weight. However, the amount of herbicides measured after the implementation of LCM for two cropping periods, was reduced by more than 75% in all cases. The method of analysis was based on the simultaneous extraction of the target compounds by mechanical shaking, followed by liquid chromatography mass spectrometric and gas chromatography electron capture (LC–MS/MS and GC–ECD) analysis. - Highlights: • Effect of Low Input Crop Management (LCM) in a vulnerable to pollution ecosystem. • LCM resulted in herbicide residues reduction in the range of 75 and 100% in all cases. • Conventional practices resulted in increased herbicide residues up to 18%. • Anthropogenic

  14. MONITORING A CONDITION OF RECOVERY OF RESIDUAL STAND AND LOGGED OVER AREA AFTER 5 YEARS RIL IMPLEMENTATION: A CASE STUDY AT A FOREST COMPANY IN CENTRAL KALIMANTAN

    Directory of Open Access Journals (Sweden)

    Sukanda Sukanda

    2007-03-01

    Full Text Available The aim of this study were to identify and evaluate a condition in logged over area (LOA after 5 years of reduced impact logging (RIL implementation, and to asses how far recovery of former skidding road, damages in felled and yarded over area, and environmental condition had taken place. Results of this study was expected to provide inputs and to improve the RIL implementation guidance for sending   sustainable forest management. The results revealed that: (1The covers of skidding road reached consecutively 2,641 m2  area (in block I, and 3,147 m2  area (in block II, as both marked by the growing of  bushes with coverage portions i.e. 84% and 80%, respectively; (2 The bush that grew on the former skidding road was regarded as pioneer vegetation; (3 The effect of cross drain on skidding road after logging was able to decrease erosion, and increase the recovery of the road condition; and (4 The healthy residual stand after 5 years logging by RIL showed that small diameter felled trees have resulted bigger residual stand damaged then big diameter or the percentage of healthy trees would be small.

  15. Residuation theory

    CERN Document Server

    Blyth, T S; Sneddon, I N; Stark, M

    1972-01-01

    Residuation Theory aims to contribute to literature in the field of ordered algebraic structures, especially on the subject of residual mappings. The book is divided into three chapters. Chapter 1 focuses on ordered sets; directed sets; semilattices; lattices; and complete lattices. Chapter 2 tackles Baer rings; Baer semigroups; Foulis semigroups; residual mappings; the notion of involution; and Boolean algebras. Chapter 3 covers residuated groupoids and semigroups; group homomorphic and isotone homomorphic Boolean images of ordered semigroups; Dubreil-Jacotin and Brouwer semigroups; and loli

  16. Amyloid-like fibrils from an 18-residue peptide analogue of a part of the central domain of the B-family of silkmoth chorion proteins.

    Science.gov (United States)

    Iconomidou, V A; Chryssikos, G D; Gionis, V; Vriend, G; Hoenger, A; Hamodrakas, S J

    2001-06-22

    Chorion is the major component of silkmoth eggshell. More than 95% of its dry mass consists of the A and B families of low molecular weight structural proteins, which have remarkable mechanical and chemical properties, and protect the oocyte and the developing embryo from the environment. We present data from negative staining, Congo red binding, X-ray diffraction, Fourier transform-Raman, attenuated total reflectance infrared spectroscopy and modelling studies of a synthetic peptide analogue of a part of the central domain of the B family of silkmoth chorion proteins, indicating that this peptide folds and self-assembles, forming amyloid-like fibrils. These results support further our proposal, based on experimental data from a synthetic peptide analogue of the central domain of the A family of chorion proteins, that silkmoth chorion is a natural, protective amyloid [Iconomidou et al., FEBS Lett. 479 (2000) 141-145].

  17. Pesticide residue concentration in soil following conventional and Low-Input Crop Management in a Mediterranean agro-ecosystem, in Central Greece.

    Science.gov (United States)

    Karasali, Helen; Marousopoulou, Anna; Machera, Kyriaki

    2016-01-15

    The present study was focused on the comparative evaluation of pesticide residues, determined in soil samples from Kopaida region, Greece before and after the implementation of Low-Input Crop Management (LCM) protocols. LCM has been suggested as an environmental friendly plant protection approach to be applied on crops growing in vulnerable to pollution ecosystems, with special focus on the site specific problems. In the case of the specific pilot area, the vulnerability was mainly related to the pollution of water bodies from agrochemicals attributed to diffuse pollution primarily from herbicides and secondarily from insecticides. A total of sixty-six soil samples, were collected and analyzed during a three-year monitoring study and the results of the determined pesticide residues were considered for the impact evaluation of applied plant protection methodology. The LCM was developed and applied in the main crops growing in the pilot area i.e. cotton, maize and industrial tomato. Herbicides active ingredients such as ethalfluralin, trifluralin, pendimethalin, S-metolachlor and fluometuron were detected in most samples at various concentrations. Ethalfluralin, which was the active ingredient present in the majority of the samples ranged from 0.01 μg g(-1) to 0.26 μg g(-1) soil dry weight. However, the amount of herbicides measured after the implementation of LCM for two cropping periods, was reduced by more than 75% in all cases. The method of analysis was based on the simultaneous extraction of the target compounds by mechanical shaking, followed by liquid chromatography mass spectrometric and gas chromatography electron capture (LC-MS/MS and GC-ECD) analysis.

  18. The selectivity of conantokin-G for ion channel inhibition of NR2B subunit-containing NMDA receptors is regulated by amino acid residues in the S2 region of NR2B.

    Science.gov (United States)

    Sheng, Zhenyu; Liang, Zhong; Geiger, James H; Prorok, Mary; Castellino, Francis J

    2009-08-01

    The conantokins are short, naturally occurring peptides that inhibit ion flow through N-methyl-d-aspartate receptor (NMDAR) channels. One member of this peptide family, conantokin-G (con-G), shows high selectivity for antagonism of NR2B-containing NMDAR channels, whereas other known conantokins are less selective inhibitors with regard to the nature of the NR2 subunit of the NMDAR complex. In order to define the molecular determinants of NR2B that govern con-G selectivity, we evaluated the ability of con-G to inhibit NMDAR ion channels expressed in human embryonic kidney (HEK)293 cells transfected with NR1, in combination with various NR2A/2B chimeras and point mutants, by electrophysiology using cells voltage-clamped in the whole-cell configuration. We found that a variant of the con-G-insensitive subunit, NR2A, in which the 158 residues comprising the S2 peptide segment (E(657)-I(814)) were replaced by the corresponding S2 region of NR2B (E(658)-I(815)), results in receptors that are highly sensitive to inhibition by con-G. Of the 22 amino acids that are different between the NR2A-S2 and the NR2B-S2 regions, exchange of one of these, M(739) of NR2B for the equivalent K(738) of NR2A, was sufficient to completely import the inhibitory activity of con-G into NR1b/NR2A-containing NMDARs. Some reinforcement of this effect was found by substitution of a second amino acid, K(755) of NR2B for Y(754) of NR2A. The discovery of the molecular determinants of NR2B selectivity with con-G has implications for the design of subunit-selective neurobiological probes and drug therapies, in addition to advancing our understanding of NR2B- versus NR2A-mediated neurological processes.

  19. Residual currents and bedform migration in a natural tidal inlet (Knudedyb, Danish Wadden Sea)

    Science.gov (United States)

    Fraccascia, S.; Winter, C.; Ernstsen, V. B.; Hebbeln, D.

    2016-10-01

    The morphology and hydrodynamics of the natural tidal inlet Knudedyb in the Danish Wadden Sea were investigated by the analysis of high resolution bathymetric data and hydrodynamic numerical modeling. In contrast to the expected anticlockwise pattern similar to the other inlets in the Wadden Sea, a clockwise tidal residual current was found, which drives the sediment transport and results from the presence of a confluent meander bend. The channel is draped by bedforms of several hierarchical scales (on average, approximately 155 m long and 2.3 m high), with average sizes decreasing from south to north and seaward (i.e., westward). Primary bedforms in the area are mostly asymmetric ebb-directed and migrate in the ebb direction in the order of 3 m yr- 1. Bedform sections at the northern channel flank show more symmetrical profiles; crests migrate flood-ward, leading to crestal flexing in the central channel. Lateral recirculation cells develop during ebb tide on both sides of the channel seaward of a bend, before the tidal reversal occurs in the rest of the model domain. As a result of the longer flood phase, a main clockwise residual eddy exists in the middle reach of the channel. Bedform migration patterns and hydrodynamic simulations reveal that the pronounced tidal asymmetry in the channel is enhanced by the effects of the channel morphology on the confined flow (at low tide).

  20. Friction and mixing effects on potential vorticity for bottom current crossing a marine strait: an application to the Sicily Channel (central Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    F. Falcini

    2014-11-01

    Full Text Available We discuss here the evolution of vorticity and potential vorticity (PV for a bottom current crossing a marine channel in shallow-water approximation, focusing on the effect of friction and mixing. We argue that bottom current vorticity is prone to significant sign changes and oscillations due to topographic effects when, in particular, the current flows over the sill of a channel. These vorticity variations are, however, modulated by frictional effects due to seafloor roughness and morphology. Such behavior is also reflected in the PV spatial evolution, which shows an abrupt peak around the sill region. Our theoretical findings are discussed by means of in situ hydrographic data related to the Eastern Mediterranean Deep Water, i.e., a dense, bottom water vein that flows northwestward, along the Sicily Channel (Mediterranean Sea. Indeed, the narrow sill of this channel implies that friction and entrainment need to be considered. Small tidal effects in the Sicily Channel allow for a steady theoretical approach. Our diagnoses on vorticity and PV allow us to obtain general insights about the effect of mixing and friction on the pathway and internal structure of bottom-trapped currents flowing through channels and straits, and to discuss spatial variability of the frictional coefficient. Our approach significantly differs from other PV-constant approaches previously used in studying the dynamics of bottom currents flowing through rotating channels.

  1. 集中式信道分配算法在WSN移动节点中的应用研究%Study on Centralized Channel Assignment Algorithm for Mobile Nodes in Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    赵军; 陈祥光; 刘春涛; 余向明; 岳彬

    2011-01-01

    为提高油料保障系统中信息采集的实时性和能量的高效性,使网关及时检测到移动设备的状态,降低无线网络间的干扰,提高网络的容量.以军用机场加油车为研究对象,提出了适用于快速移动节点的集中式信道分配算法和功率分级的能量控制方法.在无线网络节点上安装两个工作在不同频道上的网络接口,通过控制协商动态的切换数据信道,平衡网络负载,以增加总的带宽.实验结果表明,采用3条数据信道便可实现信道的集中式分配和发送功率的分级控制,有效地扩展了网络的容量和提高能量的高效性.%By investigating the working process of tanker trucks in a military airport, this paper proposes a centralized channel assignment algorithm and a power rating control method for fast-moving nodes to improve the real-time property and energy efficiency of the information collection, detect the state of mobile devices promptly, reduce interference between wireless networks and to increase network capacity in oil security systems. Considering the fact that IEEE 802. 11 wireless LAN standard defines a number of non-overlapping channels which could be used at the same time, two wireless network interfaces operating on different channels could be installed to every node. Through the negotiation on the control channel and switching the data channel dynamically, the balance of network loads could be fulfilled so as to increase the total bandwidth. Simulation and application results demonstrate that, only three data channels is needed to realize the centralized channel assignment and the power rating control, and the network capacity and energy efficiency could be improved effectively.

  2. Central functions of bicarbonate in S-type anion channel activation and OST1 protein kinase in CO 2 signal transduction in guard cell

    KAUST Repository

    Xue, Shaowu

    2011-03-18

    Plants respond to elevated CO(2) via carbonic anhydrases that mediate stomatal closing, but little is known about the early signalling mechanisms following the initial CO(2) response. It remains unclear whether CO(2), HCO(3)(-) or a combination activates downstream signalling. Here, we demonstrate that bicarbonate functions as a small-molecule activator of SLAC1 anion channels in guard cells. Elevated intracellular [HCO(3)(-)](i) with low [CO(2)] and [H(+)] activated S-type anion currents, whereas low [HCO(3)(-)](i) at high [CO(2)] and [H(+)] did not. Bicarbonate enhanced the intracellular Ca(2+) sensitivity of S-type anion channel activation in wild-type and ht1-2 kinase mutant guard cells. ht1-2 mutant guard cells exhibited enhanced bicarbonate sensitivity of S-type anion channel activation. The OST1 protein kinase has been reported not to affect CO(2) signalling. Unexpectedly, OST1 loss-of-function alleles showed strongly impaired CO(2)-induced stomatal closing and HCO(3)(-) activation of anion channels. Moreover, PYR/RCAR abscisic acid (ABA) receptor mutants slowed but did not abolish CO(2)/HCO(3)(-) signalling, redefining the convergence point of CO(2) and ABA signalling. A new working model of the sequence of CO(2) signalling events in gas exchange regulation is presented.

  3. Kv7 channels in modulation of central monoaminergic neurotransmission%Kv7(KCNQ)钾离子通道对中枢单胺能神经传递的调控

    Institute of Scientific and Technical Information of China (English)

    赵晨; 张海林

    2014-01-01

    KCNQ 基因编码5种 Kv7钾离子通道亚型( Kv7.1-Kv7.5),其中4种(Kv7.2-Kv7.5)表达于中枢神经系统内。神经元Kv7通道参与突触前后神经递质的调节,激活Kv7通道能够降低神经元兴奋性,减少单胺类神经递质释放, Kv7通道开放剂为单胺类神经元过度兴奋所致疾病(如精神分裂、焦虑、药物滥用等)提供了新的治疗方案,该文将针对Kv7通道在单胺类神经系统内的表达、功能及Kv7通道开放剂在治疗神经元过度兴奋所致疾病中的作用进行总结。%The KCNQ gene family encodes five Kv7 channel sub-units(Kv7. 1-5) and four of these (Kv7. 2-5) channels are ex-pressed in the central nervous system ( CNS ) . Neuronal Kv7 channels participate in both pre-and post-synaptic modulation of neurotransmissions. Activation of neuronal Kv7 channels inhibits neuronal excitability and limits the release of monoaminergic neu-rotransmitter. Kv7 channel openers provide novel therapeutic op-tions in the treatment of disease states characterized by overactiv-ity of monoaminergic neurons ( e. g. schizophrenia, anxiety and drug abuse) . This review summarizes the studies on expression and functional role of Kv7 channels in monoaminergic neurotrans-mission in the CNS and the potential therapeutic effect of Kv7 channel openers on the disease characterized by overactivity of monoaminergic neurons.

  4. Two distinct pools of large-conductance calcium-activated potassium channels in the somatic plasma membrane of central principal neurons

    OpenAIRE

    Kaufmann, W.A.; Kasugai, Y.; Ferraguti, F.; Storm, J F

    2010-01-01

    Although nerve cell membranes are often assumed to be uniform with respect to electrical properties, there is increasing evidence for compartmentalization into subdomains with heterogeneous impacts on the overall cell function. Such microdomains are characterized by specific sets of proteins determining their functional properties. Recently, clustering of large-conductance calcium-activated potassium (BKCa) channels was shown at sites of subsurface membrane cisterns in cerebellar Purkinje cel...

  5. Analysis of the action of lidocaine on insect sodium channels

    OpenAIRE

    Song, Weizhong; Silver, Kristopher S.; Du, Yuzhe; Liu, Zhiqi; Dong, Ke

    2010-01-01

    A new class of sodium channel blocker insecticides (SCBIs), which include indoxacarb, its active metabolite, DCJW, and metaflumizone, preferably block inactivated states of both insect and mammalian sodium channels in a manner similar to that by which local anesthetic (LA) drugs block mammalian sodium channels. A recent study showed that two residues in the cockroach sodium channel, F1817 and Y1824, corresponding to two key LA-interacting residues identified in mammalian sodium channels are n...

  6. Residual circulation and tidal stress in the Gulf of California

    Science.gov (United States)

    Salas-De-León, David Alberto; Carbajal-PéRez, Noel; Monreal-Gómez, Maria Adela; Barrientos-MacGregor, Gerardo

    2003-10-01

    Results of a three-dimensional nonlinear barotropic shelf model are used to study the effect of the M2 tidal stress on the residual current in the Gulf of California. The tidal stress summarizes the nonlinear interactions and forces the residual circulation. It is calculated following the method developed by [1975]. The vertical structure of the tidal stress reveals clearly the zones where the interaction between tidal currents and the basin geometry is strong. The highest values of tidal stress were found over the Salsipuedes sill and in the Ballenas Channel in the central archipelago and in the Colorado River Delta. Relatively high values of tidal stress were also found in deeper layers in the southern part. The high tidal stress values coincide well with the anomalous cold-water patches observed in the archipelago area, attributed to tidal mixing. The calculated residual currents show a maximum of about 15 cm s-1 in the upper layers in the archipelago area. At subsurface layers an anticyclonic circulation is observed. Divergence patterns in the upper layers suggest that M2 tide residuals contribute, to significant upward movements of water, on the west side of Tiburón island. This barotropic process may contribute to the generation of the observed cold patches.

  7. Circulating insulin stimulates fatty acid retention in white adipose tissue via KATP channel activation in the central nervous System only in insulin-sensitive mice

    NARCIS (Netherlands)

    Coomans, C.P.; Geerling, J.J.; Guigas, B.; Hoek, A.M. van den; Parlevliet, E.T.; Ouwens, D.M.; Pijl, H.; Voshol, P.J.; Rensen, P.C.N.; Havekes, L.M.; Romijn, J.A.

    2011-01-01

    Insulin signaling in the central nervous system (CNS) is required for the inhibitory effect of insulin on glucose production. Our aim was to determine whether the CNS is also involved in the stimulatory effect of circulating insulin on the tissue-specific retention of fatty acid (FA) from plasma. In

  8. Curative treatment for central nervous system medulloepithelioma despite residual disease after resection. Report of two cases treated according to the GPHO protocol HIT 2000 and review of the literature

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Klaus [Leipzig Univ. (Germany). Dept. of Radiotherapy and Radiooncology; Zwiener, Isabella [University Medical Center Univ. Mainz (Germany). Inst. for Medical Biostatistics, Epidemiology and Informatics; Welker, Helmut [Katharinenhospital, Stuttgart (Germany). Dept. of Radiotherapy and Radiooncology; Maass, Eberhard [Klinikum Stuttgart - Olgahospital (DE). Pediatrics 5 (Oncology, Hematology, Immunology); Bongartz, Rudolf [Koeln Univ. (Germany). Dept. of Radiotherapy and Radiooncology; Berthold, Frank [Koeln Univ. (Germany). Dept. of Pediatric Oncology; Pietsch, Torsten [Bonn Univ. Medical Center (Germany). Dept. of Neuropathology; Warmuth-Metz, Monika [Wuerzburg Univ. (Germany). Dept. of Neuroradiology; Bueren, Andre von; Rutkowski, Stefan [University Medical Center Hamburg-Eppendorf, Hamburg (Germany). Dept. of Pediatric Hematology and Oncology

    2011-11-15

    Medulloepithelioma of the central nervous system (CNS) is an uncommon primitive neuroectodermal tumor (PNET) usually occurring in early childhood. It is characterized by highly malignant behavior with a propensity for progression, recurrence, and dissemination despite intensive therapy. Due to its rarity, the optimal management is still unknown. However, gross total resection (GTR) has been considered crucial to achieve cure. In this article, the authors report on 2 cases of CNS medulloepithelioma in which long-term survival (more than 6 years) could be achieved despite evidence of, or suspected postoperative residual disease with an otherwise dismal prognosis. The patients were treated according to different strata of the protocol for primitive neuroectodermal tumors (PNET) of the German-Austrian multicenter trial of the German Society for Pediatric Oncology and Hematology (GPOH) for childhood brain tumors (HIT 2000). Treatment included postoperative hyperfractionated radiotherapy of the craniospinal axis followed by a boost to the tumor site in combination with chemotherapy. A review of the 2 reported and 37 previously published cases confirmed GTR and older age as positive prognostic factors. (orig.)

  9. Curative treatment for central nervous system medulloepithelioma despite residual disease after resection. Report of two cases treated according to the GPHO Protocol HIT 2000 and review of the literature.

    Science.gov (United States)

    Müller, Klaus; Zwiener, Isabella; Welker, Helmut; Maass, Eberhard; Bongartz, Rudolf; Berthold, Frank; Pietsch, Torsten; Warmuth-Metz, Monika; von Bueren, André; Rutkowski, Stefan

    2011-11-01

    Medulloepithelioma of the central nervous system (CNS) is an uncommon primitive neuroectodermal tumor (PNET) usually occurring in early childhood. It is characterized by highly malignant behavior with a propensity for progression, recurrence, and dissemination despite intensive therapy. Due to its rarity, the optimal management is still unknown. However, gross total resection (GTR) has been considered crucial to achieve cure. In this article, the authors report on 2 cases of CNS medulloepithelioma in which long-term survival (more than 6 years) could be achieved despite evidence of, or suspected postoperative residual disease with an otherwise dismal prognosis.The patients were treated according to different strata of the protocol for primitive neuroectodermal tumors (PNET) of the German-Austrian multicenter trial of the German Society for Pediatric Oncology and Hematology (GPOH) for childhood brain tumors (HIT 2000). Treatment included postoperative hyperfractionated radiotherapy of the craniospinal axis followed by a boost to the tumor site in combination with chemotherapy. A review of the 2 reported and 37 previously published cases confirmed GTR and older age as positive prognostic factors.

  10. Joint Source-Channel Decoding Scheme for Image Transmission over Wireless Channel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We improve the iterative decoding algorithm by utilizing the "leaked" residual redundancy at the output of the source encoder without changing the encoder structure for the noisy channel.The experimental results show that using the residual redundancy of the compressed source in channel decoding is an effective method to improve the error correction performance.

  11. Stratigraphy and paleogeographic significance of a Late Pennsylvanian to Early Permian channeled slope sequence in the Darwin Basin, southern Darwin Hills, east-central California

    Science.gov (United States)

    Stevens, Calvin H.; Stone, Paul; Magginetti, Robert T.; Ritter, Scott M.

    2015-01-01

    The complex stratigraphy of late Paleozoic rocks in the southern Darwin Hills consists of regionally extensive Mississippian and Early to Middle Pennsylvanian rocks overlain by latest Pennsylvanian to Early Permian rocks, herein called the Darwin Hills sequence. Deposition of this latter sequence marked the beginning of the Darwin Basin. In Mississippian time, a carbonate platform prograded westward over slightly older slope deposits. In the Late Mississippian this platform was exposed to erosion and siliciclastic sediments were deposited. In Early to Middle Pennsylvanian time the area subsided, forming a west-facing ramp that was subjected to deformation and erosion in Middle or early Late Pennsylvanian time. Later this area was tilted westward and deep-water sediments were deposited on this slope. In latest Pennsylvanian to earliest Permian time, a major channel was cut through the older Pennsylvanian rocks and into the Upper Mississippian strata. This channel was gradually filled with increasingly finer grained, deep-water sediment as the area evolved into a basin floor by Early Permian (Sakmarian) time. Expansion of the Darwin Basin in Artinskian time led to a second phase of deposition represented by strata of the regionally extensive Darwin Canyon Formation. The geology in this small area thus documents tectonic events occurring during the early development of the Darwin Basin.

  12. Radio-protection and decontamination operations on the central vibrating channels of the reactor G 3; Radioprotection et operations de decontamination sur le couloir vibrant central de la pile G.3

    Energy Technology Data Exchange (ETDEWEB)

    Chassany, J.Ph.; Cohendy, G.; Rodier, J. [Commissariat a l' Energie Atomique, Centre de Production de Plutonium, Marcoule (France). Centre d' Etudes Nucleaires

    1965-07-01

    The dose rate in the vibrating channels room of the discharge system, which is due to the contamination of one of the channels by a ruptured can after clad failure was high. It was necessary to intervene in order that normal maintenance could be carried out on this equipment. The operation was carried out from a neighbouring room using cleaning tubes, and then directly, after numerous precautions had been taken. Radio-protection was made very difficult because of the irradiation and of the powdery state of the contamination. The average individual integrated dose for the 122 persons having taken part in this 2-month operation was 362 mrem. Thanks to the close collaboration between the operational, emergency and radio-protection personnel, this operation was executed smoothly and rapidly. (authors) [French] Le debit de dose dans la salle des couloirs vibrants du systeme de dechargement, provenant de la contamination de l'un d'entre eux par une cartouche a rupture de gaine etait important. Une intervention a ete necessaire pour permettre l'entretien normal de ce materiel. Elle s'est faite d'abord a partir d'une salle voisine, en utilisant des tuyaux de lavage, puis directement, moyennant de nombreuses precautions. La radioprotection a ete rendue tres difficile a cause de l'irradiation et de la forme particulierement pulverulente de la contamination. La dose individuelle moyenne integree par les 122 agents ayant participe a cette operation qui a dure 2 mois, a ete de 362 mrem. C'est grace a la collaboration etroite de l'exploitation, de l'intervention et de la radioprotection qu'elle a pu se derouler aussi rapidement dans de bonnes conditions. (auteurs)

  13. Investigation and prevention of residual detergents on tableware treated by centralized disinfection enterprises in Nanning%南宁市集中式餐饮具消毒洗涤剂残留量调查及控制对策

    Institute of Scientific and Technical Information of China (English)

    张东生; 冯少雄; 黄涛

    2012-01-01

    目的 为掌握南宁市集中式餐饮具消毒企业消毒餐饮具的洗涤剂残留量情况,为监督工作提供理论依据.方法 从2009年至2011年间,全市20家集中式餐饮具消毒企业消毒的餐饮具,按照标准检测并评价消毒餐饮具表面烷基(苯)磺酸钠残留量合格情况,结合清洗工艺流程的监督检查情况,分析存在问题,提出控制措施.结果 大中小消毒企业的碗碟勺的消毒洗涤剂残留量检测合格率均较高;大中小消毒企业的筷子的消毒洗涤剂残留量检测合格率均较低,三者合格率差异有统计学意义(P<0.05);筷子“再清水浸泡”环节残留量检测合格率88.1%比未“再清水浸泡”流程的残留量检测合格率60.8%高,两者合格率差异有统计学意义(P<0.01);筷子再浸泡时间越长,合格率也随之提高,浸泡5~6 min以上的筷子,合格率为100%.结论 洗涤剂残留量的控制措施重点在餐饮具清洗流程的工艺,对竹子或密胺的筷子清洗浸泡流程的监督检查尤其重要.%Objective To master the situation of residual detergents on tableware treated by centralized disinfection enterprises in Nanning, and to provide a theoretical basis for supervision. Methods The detergent residues on tableware from 20 centralized disinfection enterprises in 2009 -2011 were detected by the national standard methods. The content of alkyl benzene sodium sulfonate remained on the surface of tableware was inspected and evaluated, and combined with inspection of cleansing technology procedure. Results The qualified rates for detergent remained on dishes and spoons in the large - , medium- and small-sized disinfection enterprises were high, while that on chopsticks were low (P <0. 05). The process of soaking chopsticks again in clean water made the qualified rate increased from 60. 8% to 88. 1 % ( P < 0.01). Soaking chopsticks in water for more than 5-6 minutes, the qualified rate could be 100%. Conclusion The

  14. Transcriptome Analysis of the Central and Peripheral Nervous Systems of the Spider Cupiennius salei Reveals Multiple Putative Cys-Loop Ligand Gated Ion Channel Subunits and an Acetylcholine Binding Protein.

    Directory of Open Access Journals (Sweden)

    Päivi H Torkkeli

    Full Text Available Invertebrates possess a diverse collection of pentameric Cys-loop ligand gated ion channel (LGIC receptors whose molecular structures, evolution and relationships to mammalian counterparts have been intensely investigated in several clinically and agriculturally important species. These receptors are targets for a variety of control agents that may also harm beneficial species. However, little is known about Cys-loop receptors in spiders, which are important natural predators of insects. We assembled de novo transcriptomes from the central and peripheral nervous systems of the Central American wandering spider Cupiennius salei, a model species for neurophysiological, behavioral and developmental studies. We found 15 Cys-loop receptor subunits that are expected to form anion or cation permeable channels, plus a putative acetylcholine binding protein (AChBP that has only previously been reported in molluscs and one annelid. We used phylogenetic and sequence analysis to compare the spider subunits to homologous receptors in other species and predicted the 3D structures of each protein using the I-Tasser server. The quality of homology models improved with increasing sequence identity to the available high-resolution templates. We found that C. salei has orthologous γ-aminobutyric acid (GABA, GluCl, pHCl, HisCl and nAChα LGIC subunits to other arthropods, but some subgroups are specific to arachnids, or only to spiders. C. salei sequences were phylogenetically closest to gene fragments from the social spider, Stegodyphus mimosarum, indicating high conservation within the Araneomorphae suborder of spiders. C. salei sequences had similar ligand binding and transmembrane regions to other invertebrate and vertebrate LGICs. They also had motifs associated with high sensitivity to insecticides and antiparasitic agents such as fipronil, dieldrin and ivermectin. Development of truly selective control agents for pest species will require information about

  15. U.S. Isostatic Residual Gravity Grid

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — isores.bin - standard grid containing isostatic residual gravity map for U.S. Grid interval = 4 km. Projection is Albers (central meridian = 96 degrees West; base...

  16. Sawdust and fruit residues of Central Amazonian for Panus strigellus spawn’s production Serragem e resíduos de frutos da Amazônia Central para produção de semente-inóculo de Panus strigellus

    Directory of Open Access Journals (Sweden)

    Ruby Vargas-Isla

    2012-06-01

    Full Text Available

    The objective of this work was to perform a screening of residues of forest species of the Central Amazon to prepare spawn of the edible mushroom Panus strigellus. Sawdust substrates from 11 forest species were tested. Then supplementation with beer yeast, cereal bran and regional fruit residues in sawdust:supplementation relation (5:1 and 10:1 were evaluated. Mycelial growth of P. strigellus occurred in all the substrates composed of the Amazonian forests species, suggesting that all have potential for use in spawn formulation and/or cultivation of this edible mushroom. Among these species the substrate formulated with Simarouba amara sawdust promoted higher mycelial growth (P<0.05. The formulation of S. amara supplemented with Astrocaryum aculeatum fruit shell bran (10:1 presented the best supplementation alternative among regional fruit residues. Three types of packaging for spawn preparation were evaluated, and the polypropylene sack (32×45 cm was considered the most appropriate. Simarouba amara sawdust and A. aculeatum fruit shell are readily available in the North region, and the results demonstrating that these residues might substitute Eucalyptus sp. sawdust and rice bran, commonly used in the South and Southeast of Brazil for mushroom spawn production.

    doi: 10.4336/2012.pfb.32.70.07

    Neste trabalho objetivou-se realizar uma triagem de resíduos de espécies florestais da Amazônia Central para o preparo da semente-inóculo do cogumelo comestível Panus strigellus. Foram testados substratos de serragem de 11 espécies florestais. Em seguida, suplementação com levedura de cerveja, farelos de cereais e resíduos de frutas regionais foram avaliados na relação serragem:suplemento (5:1 e 10:1. O crescimento micelial de P. strigellus ocorreu em todos os substratos formulados com espécies florestais da Amazônia, apresentando potencial de uso na formulação da semente-inóculo e/ou cultivo deste fungo comestível. Entre

  17. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides.

    Science.gov (United States)

    Sayono, Sayono; Hidayati, Anggie Puspa Nur; Fahri, Sukmal; Sumanto, Didik; Dharmana, Edi; Hadisaputro, Suharyo; Asih, Puji Budi Setia; Syafruddin, Din

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%-15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C) and one synonymous polymorphism (codon 982) were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF) and allele 7 (PGF) represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97-7.8 and OR = 7.37, CI: 2.4-22.5, respectively). This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring.

  18. Distribution of Voltage-Gated Sodium Channel (Nav Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides.

    Directory of Open Access Journals (Sweden)

    Sayono Sayono

    Full Text Available The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%-15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C and one synonymous polymorphism (codon 982 were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF and allele 7 (PGF represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97-7.8 and OR = 7.37, CI: 2.4-22.5, respectively. This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring.

  19. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides

    Science.gov (United States)

    Sayono, Sayono; Hidayati, Anggie Puspa Nur; Fahri, Sukmal; Sumanto, Didik; Dharmana, Edi; Hadisaputro, Suharyo; Asih, Puji Budi Setia; Syafruddin, Din

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%–15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C) and one synonymous polymorphism (codon 982) were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF) and allele 7 (PGF) represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97–7.8 and OR = 7.37, CI: 2.4–22.5, respectively). This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring. PMID:26939002

  20. Impact of histidine residues on the transmembrane helices of viroporins.

    Science.gov (United States)

    Wang, Yan; Park, Sang Ho; Tian, Ye; Opella, Stanley J

    2013-11-01

    Abstract The role of histidine in channel-forming transmembrane (TM) helices was investigated by comparing the TM helices from Virus protein 'u' (Vpu) and the M2 proton channel. Both proteins are members of the viroporin family of small membrane proteins that exhibit ion channel activity, and have a single TM helix that is capable of forming oligomers. The TM helices from both proteins have a conserved tryptophan towards the C-terminus. Previously, alanine 18 of Vpu was mutated to histidine in order to artificially introduce the same HXXXW motif that is central to the proton channel activity of M2. Interestingly, the mutated Vpu TM resulted in an increase in helix tilt angle of 11° in lipid bilayers compared to the wild-type Vpu TM. Here, we find the reverse, when histidine 37 of the HXXXW motif in M2 was mutated to alanine, it decreased the helix tilt by 10° from that of wild-type M2. The tilt change is independent of both the helix length and the presence of tryptophan. In addition, compared to wild-type M2, the H37A mutant displayed lowered sensitivity to proton concentration. We also found that the solvent accessibility of histidine-containing M2 is greater than without histidine. This suggests that the TM helix may increase the solvent exposure by changing its tilt angle in order to accommodate a polar/charged residue within the hydrophobic membrane region. The comparative results of M2, Vpu and their mutants demonstrated the significance of histidine in a transmembrane helix and the remarkable plasticity of the function and structure of ion channels stemming from changes at a single amino acid site.

  1. Cholesterol binding to ion channels

    Directory of Open Access Journals (Sweden)

    Irena eLevitan

    2014-02-01

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

  2. A joint source/channel coder design

    Science.gov (United States)

    Sayood, Khalid; Liu, Fuling; Gibson, Jerry D.

    1992-01-01

    The situation where there is residual redundancy at the source coder output is examined. This residual redundancy can be used to provide error correction without a channel encoder. This approach is extended to conventional source coder/convolutional coder combinations. A design for nonbinary encoders for this situation is also developed. Through simulation results it is shown that the proposed systems consistently outperform conventional source-channel coder pairs with gains of greater than 10 dB at high probability of error.

  3. Structure of the proton-gated urea channel from the gastric pathogen Helicobacter pylori.

    Science.gov (United States)

    Strugatsky, David; McNulty, Reginald; Munson, Keith; Chen, Chiung-Kuang; Soltis, S Michael; Sachs, George; Luecke, Hartmut

    2013-01-10

    Half the world's population is chronically infected with Helicobacter pylori, causing gastritis, gastric ulcers and an increased incidence of gastric adenocarcinoma. Its proton-gated inner-membrane urea channel, HpUreI, is essential for survival in the acidic environment of the stomach. The channel is closed at neutral pH and opens at acidic pH to allow the rapid access of urea to cytoplasmic urease. Urease produces NH(3) and CO(2), neutralizing entering protons and thus buffering the periplasm to a pH of roughly 6.1 even in gastric juice at a pH below 2.0. Here we report the structure of HpUreI, revealing six protomers assembled in a hexameric ring surrounding a central bilayer plug of ordered lipids. Each protomer encloses a channel formed by a twisted bundle of six transmembrane helices. The bundle defines a previously unobserved fold comprising a two-helix hairpin motif repeated three times around the central axis of the channel, without the inverted repeat of mammalian-type urea transporters. Both the channel and the protomer interface contain residues conserved in the AmiS/UreI superfamily, suggesting the preservation of channel architecture and oligomeric state in this superfamily. Predominantly aromatic or aliphatic side chains line the entire channel and define two consecutive constriction sites in the middle of the channel. Mutation of Trp 153 in the cytoplasmic constriction site to Ala or Phe decreases the selectivity for urea in comparison with thiourea, suggesting that solute interaction with Trp 153 contributes specificity. The previously unobserved hexameric channel structure described here provides a new model for the permeation of urea and other small amide solutes in prokaryotes and archaea.

  4. KCNE1 induces fenestration in the Kv7.1/KCNE1 channel complex that allows for highly specific pharmacological targeting

    Science.gov (United States)

    Wrobel, Eva; Rothenberg, Ina; Krisp, Christoph; Hundt, Franziska; Fraenzel, Benjamin; Eckey, Karina; Linders, Joannes T. M.; Gallacher, David J.; Towart, Rob; Pott, Lutz; Pusch, Michael; Yang, Tao; Roden, Dan M.; Kurata, Harley T.; Schulze-Bahr, Eric; Strutz-Seebohm, Nathalie; Wolters, Dirk; Seebohm, Guiscard

    2016-01-01

    Most small-molecule inhibitors of voltage-gated ion channels display poor subtype specificity because they bind to highly conserved residues located in the channel's central cavity. Using a combined approach of scanning mutagenesis, electrophysiology, chemical ligand modification, chemical cross-linking, MS/MS-analyses and molecular modelling, we provide evidence for the binding site for adamantane derivatives and their putative access pathway in Kv7.1/KCNE1 channels. The adamantane compounds, exemplified by JNJ303, are highly potent gating modifiers that bind to fenestrations that become available when KCNE1 accessory subunits are bound to Kv7.1 channels. This mode of regulation by auxiliary subunits may facilitate the future development of potent and highly subtype-specific Kv channel inhibitors. PMID:27731317

  5. KCNE1 induces fenestration in the Kv7.1/KCNE1 channel complex that allows for highly specific pharmacological targeting

    Science.gov (United States)

    Wrobel, Eva; Rothenberg, Ina; Krisp, Christoph; Hundt, Franziska; Fraenzel, Benjamin; Eckey, Karina; Linders, Joannes T. M.; Gallacher, David J.; Towart, Rob; Pott, Lutz; Pusch, Michael; Yang, Tao; Roden, Dan M.; Kurata, Harley T.; Schulze-Bahr, Eric; Strutz-Seebohm, Nathalie; Wolters, Dirk; Seebohm, Guiscard

    2016-10-01

    Most small-molecule inhibitors of voltage-gated ion channels display poor subtype specificity because they bind to highly conserved residues located in the channel's central cavity. Using a combined approach of scanning mutagenesis, electrophysiology, chemical ligand modification, chemical cross-linking, MS/MS-analyses and molecular modelling, we provide evidence for the binding site for adamantane derivatives and their putative access pathway in Kv7.1/KCNE1 channels. The adamantane compounds, exemplified by JNJ303, are highly potent gating modifiers that bind to fenestrations that become available when KCNE1 accessory subunits are bound to Kv7.1 channels. This mode of regulation by auxiliary subunits may facilitate the future development of potent and highly subtype-specific Kv channel inhibitors.

  6. The central mechanism underlying hypertension: a review of the roles of sodium ions, epithelial sodium channels, the renin-angiotensin-aldosterone system, oxidative stress and endogenous digitalis in the brain.

    Science.gov (United States)

    Takahashi, Hakuo; Yoshika, Masamichi; Komiyama, Yutaka; Nishimura, Masato

    2011-11-01

    The central nervous system has a key role in regulating the circulatory system by modulating the sympathetic and parasympathetic nervous systems, pituitary hormone release, and the baroreceptor reflex. Digoxin- and ouabain-like immunoreactive materials were found >20 years ago in the hypothalamic nuclei. These factors appeared to localize to the paraventricular and supraoptic nuclei and the nerve fibers at the circumventricular organs and supposed to affect electrolyte balance and blood pressure. The turnover rate of these materials increases with increasing sodium intake. As intracerebroventricular injection of ouabain increases blood pressure via sympathetic activation, an endogenous digitalis-like factor (EDLF) was thought to regulate cardiovascular system-related functions in the brain, particularly after sodium loading. Experiments conducted mainly in rats revealed that the mechanism of action of ouabain in the brain involves sodium ions, epithelial sodium channels (ENaCs) and the renin-angiotensin-aldosterone system (RAAS), all of which are affected by sodium loading. Rats fed a high-sodium diet develop elevated sodium levels in their cerebrospinal fluid, which activates ENaCs. Activated ENaCs and/or increased intracellular sodium in neurons activate the RAAS; this releases EDLF in the brain, activating the sympathetic nervous system. The RAAS promotes oxidative stress in the brain, further activating the RAAS and augmenting sympathetic outflow. Angiotensin II and aldosterone of peripheral origin act in the brain to activate this cascade, increasing sympathetic outflow and leading to hypertension. Thus, the brain Na(+)-ENaC-RAAS-EDLF axis activates sympathetic outflow and has a crucial role in essential and secondary hypertension. This report provides an overview of the central mechanism underlying hypertension and discusses the use of antihypertensive agents.

  7. A specific two-pore domain potassium channel blocker defines the structure of the TASK-1 open pore.

    Science.gov (United States)

    Streit, Anne K; Netter, Michael F; Kempf, Franca; Walecki, Magdalena; Rinné, Susanne; Bollepalli, Murali K; Preisig-Müller, Regina; Renigunta, Vijay; Daut, Jürgen; Baukrowitz, Thomas; Sansom, Mark S P; Stansfeld, Phillip J; Decher, Niels

    2011-04-22

    Two-pore domain potassium (K(2P)) channels play a key role in setting the membrane potential of excitable cells. Despite their role as putative targets for drugs and general anesthetics, little is known about the structure and the drug binding site of K(2P) channels. We describe A1899 as a potent and highly selective blocker of the K(2P) channel TASK-1. As A1899 acts as an open-channel blocker and binds to residues forming the wall of the central cavity, the drug was used to further our understanding of the channel pore. Using alanine mutagenesis screens, we have identified residues in both pore loops, the M2 and M4 segments, and the halothane response element to form the drug binding site of TASK-1. Our experimental data were used to validate a K(2P) open-pore homology model of TASK-1, providing structural insights for future rational design of drugs targeting K(2P) channels.

  8. Resíduos de agrotóxicos na água de rios da Depressão Central do Estado do Rio Grande do Sul, Brasil Residues of pesticides in the water of the Depression Central rivers in the State of Rio Grande do Sul, Brazil

    Directory of Open Access Journals (Sweden)

    Enio Marchesan

    2010-05-01

    Full Text Available A atividade orizícola é conduzida com uso intensivo de agrotóxicos, os quais, dependendo do manejo e das precipitações pluviais, podem chegar até os rios. O objetivo do trabalho foi determinar resíduos dos herbicidas clomazona, quincloraque, propanil, bentazona, 2,4-D e imazethapyr e dos inseticidas carbofurano e fipronil nos rios Vacacaí e Vacacaí-Mirim, situados na Depressão Central do Rio Grande do Sul, nas safras de 2003/04 a 2007/08, com coletas realizadas de novembro a fevereiro (cultivo do arroz. As análises dos herbicidas e do carbofurano foram realizadas por HPLC-DAD, e a análise do fipronil foi realizada por GC-ECD. Na safra 2003/04, em ambos os rios, os herbicidas clomazona, 2,4-D e propanil foram os mais frequentes nas amostras de água. Na safra 2004/05, o quincloraque foi detectado em maior número de amostras, já nas safras 2005/06 e 2006/07 fipronil foi o agrotóxico mais frequente nas amostras nos rios Vacacaí e Vacacaí-Mirim. Na safra de 2007/08, houve menor presença de resíduos de agrotóxicos nos rios Vacacaí e Vacacaí-Mirim. Há presença de agrotóxicos utilizados na lavoura de arroz nos rios Vacacaí e Vacacaí-Mirim durante o período de cultivo de arroz irrigado, destacando-se, entre os analisados, os herbicidas clomazona e quincloraque e o inseticida fipronil.The rice-growing activity is conducted out with intensive use of agrochemicals, which, depending on the management and rainfall can reach rivers. The study aimed to determine the residues of herbicides clomazone, quinclorac, propanil, bentazone, 2,4-D and imazethapyr and insecticides carbofuran and fipronil in the Vacacaí and Vacacaí-Mirim rivers, located in the Central Depression of Rio Grande do Sul, in the crop of 2003/04 untill 2007/08. Samples were collected from November to February (rice growing season. Analysis of herbicides and carbofuran were performed by HPLC-DAD and fipronil by GC-ECD. During 2003/04, in both rivers, the herbicide

  9. Ion channel stability and hydrogen bonding. Molecular modelling of channels formed by synthetic alamethicin analogues.

    Science.gov (United States)

    Breed, J; Kerr, I D; Molle, G; Duclohier, H; Sansom, M S

    1997-12-04

    Several analogues of the channel-forming peptaibol alamethicin have been demonstrated to exhibit faster switching between channel substates than does unmodified alamethicin. Molecular modelling studies are used to explore the possible molecular basis of these differences. Models of channels formed by alamethicin analogues were generated by restrained molecular dynamics in vacuo and refined by short molecular dynamics simulations with water molecules within and at either mouth of the channel. A decrease in backbone solvation was found to correlate with a decrease in open channel stability between alamethicin and an analogue in which all alpha-amino-isobutyric acid residues of alamethicin were replaced by leucine. A decrease in the extent of hydrogen-bonding at residue 7 correlates with lower open channel stabilities of analogues in which the glutamine at position 7 was replaced by smaller polar sidechains. These two observations indicate the importance of alamethicin/water H-bonds in stabilizing the open channel.

  10. Eight channel telephone telemetry system

    Science.gov (United States)

    Smith, R. E.

    1973-01-01

    A portable, indirectly coupled telephone system is reported which transmits/to a central receiving site eight channels of EEG data of sufficient fidelity for screening and/or limited diagnostic use. The system requires no electrical connection to the telephone at the transmitter or at the receiver and is compatible with common EEG recording practice for real-time recording. It accepts 8 input channels simultaneously with one telephone transmitter and one telephone receiver operates from standard power sources.

  11. The Molecular Basis of Polyunsaturated Fatty Acid Interactions with the Shaker Voltage-Gated Potassium Channel.

    Directory of Open Access Journals (Sweden)

    Samira Yazdi

    2016-01-01

    Full Text Available Voltage-gated potassium (KV channels are membrane proteins that respond to changes in membrane potential by enabling K+ ion flux across the membrane. Polyunsaturated fatty acids (PUFAs induce channel opening by modulating the voltage-sensitivity, which can provide effective treatment against refractory epilepsy by means of a ketogenic diet. While PUFAs have been reported to influence the gating mechanism by electrostatic interactions to the voltage-sensor domain (VSD, the exact PUFA-protein interactions are still elusive. In this study, we report on the interactions between the Shaker KV channel in open and closed states and a PUFA-enriched lipid bilayer using microsecond molecular dynamics simulations. We determined a putative PUFA binding site in the open state of the channel located at the protein-lipid interface in the vicinity of the extracellular halves of the S3 and S4 helices of the VSD. In particular, the lipophilic PUFA tail covered a wide range of non-specific hydrophobic interactions in the hydrophobic central core of the protein-lipid interface, while the carboxylic head group displayed more specific interactions to polar/charged residues at the extracellular regions of the S3 and S4 helices, encompassing the S3-S4 linker. Moreover, by studying the interactions between saturated fatty acids (SFA and the Shaker KV channel, our study confirmed an increased conformational flexibility in the polyunsaturated carbon tails compared to saturated carbon chains, which may explain the specificity of PUFA action on channel proteins.

  12. Mechanosensitive Channels

    Science.gov (United States)

    Martinac, Boris

    Living cells are exposed to a variety of mechanical stimuli acting throughout the biosphere. The range of the stimuli extends from thermal molecular agitation to potentially destructive cell swelling caused by osmotic pressure gradients. Cellular membranes present a major target for these stimuli. To detect mechanical forces acting upon them cell membranes are equipped with mechanosensitive (MS) ion channels. Functioning as molecular mechanoelectrical transducers of mechanical forces into electrical and/or chemical intracellular signals these channels play a critical role in the physiology of mechanotransduction. Studies of prokaryotic MS channels and recent work on MS channels of eukaryotes have significantly increased our understanding of their gating mechanism, physiological functions, and evolutionary origins as well as their role in the pathology of disease.

  13. TRP channels and psychiatric disorders.

    Science.gov (United States)

    Chahl, Loris A

    2011-01-01

    Depression and schizophrenia are major psychiatric disorders that cause much human suffering. Current treatments have major limitations and new drug targets are eagerly sought. Study of transient receptor potential (TRP) channels in these disorders is at an early stage and the potential of agents that activate or inhibit these channels remains speculative. The findings that TRPC6 channels promote dendritic growth and are selectively activated by hyperforin, the key constitutent of St John's wort, suggest that TRPC6 channels might prove to be a new target for antidepressant drug development. There is now considerable evidence that TRPV1 antagonists have anxiolytic activity but there is no direct evidence that they have antidepressant activity. There is also no direct evidence that TRP channels play a role in schizophrenia. However, the findings that TRPC channels are involved in neuronal development and fundamental synaptic mechanisms, and that TRPV1 channels play a role in central dopaminergic and cannabinoid mechanisms is suggestive of potential roles of these channels in schizophrenia. Investigation of TRP channels in psychiatric disorders holds the promise of yielding further understanding of the aetiology of psychiatric disorders and the development of new drug treatments.

  14. Post-Translational Modifications of TRP Channels

    Directory of Open Access Journals (Sweden)

    Olaf Voolstra

    2014-04-01

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

  15. Negative particle planar and axial channeling and channeling collimation

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, Richard A., Jr.; /Fermilab

    2009-12-01

    While information exists on high energy negative particle channeling there has been little study of the challenges of negative particle bending and channeling collimation. Partly this is because negative dechanneling lengths are relatively much shorter. Electrons are not particularly useful for investigating negative particle channeling effects because their material interactions are dominated by channeling radiation. Another important factor is that the current central challenge in channeling collimation is the proton-proton Large Hadron Collider (LHC) where both beams are positive. On the other hand in the future the collimation question might reemerge for electon-positron or muon colliders. Dechanneling lengths increase at higher energies so that part of the negative particle experimental challenge diminishes. In the article different approaches to determining negative dechanneling lengths are reviewed. The more complicated case for axial channeling is also discussed. Muon channeling as a tool to investigate dechanneling is also discussed. While it is now possible to study muon channeling it will probably not illuminate the study of negative dechanneling.

  16. A conserved threonine in the S1-S2 loop of KV7.2 and K V7.3 channels regulates voltage-dependent activation.

    Science.gov (United States)

    Füll, Yvonne; Seebohm, Guiscard; Lerche, Holger; Maljevic, Snezana

    2013-06-01

    The voltage-gated potassium channels KV7.2 and KV7.3 (KCNQ2/3 genes) play an important role in regulating neuronal excitability. More than 50 KCNQ2/3 mutations have been identified to cause an inherited form of epilepsy in newborns. For two of those (E119G and S122L) found in the S1-S2 region of KV7.2, we previously showed a decreased channel availability mainly at action potential subthreshold voltages caused by a slight depolarizing shift of the activation curve. Interestingly, recent studies revealed that a threonine residue within the S1-S2 loop, highly conserved among different classes of KV channels, is crucial for both their function and surface expression. To investigate the functional role of the homologous threonine residues in KV7.2 (T114) and KV7.3 (T144) channels, we replaced them with alanine and examined the electrophysiological properties using heterologous expression in CHO cells and whole cell patch clamping. Channels comprising mutant subunits yielded decreased potassium currents with slowed activation and accelerated deactivation kinetics. However, the most striking effect was a depolarizing shift in the voltage dependence of activation reaching +30 mV upon co-expression of both mutant subunits. Potential interactions of T114 within the channel were analyzed by creating a 3D homology model of KV7.2 in an open state suggesting that this residue plays a central role in the formation of a stable interface between the S1-S2 and the S5 segment helices. This could be the explanation why substitution of the conserved threonine in KV7.2 and KV7.3 channels destabilizes the open and favors the closed state of these channels.

  17. Single-channel kinetics of BK (Slo1 channels

    Directory of Open Access Journals (Sweden)

    Yanyan eGeng

    2015-01-01

    Full Text Available Single-channel kinetics has proven a powerful tool to reveal information about the gating mechanisms that control the opening and closing of ion channels. This introductory review focuses on the gating of large conductance Ca2+- and voltage-activated K+ (BK or Slo1 channels at the single-channel level. It starts with single-channel current records and progresses to presentation and analysis of single-channel data and the development of gating mechanisms in terms of discrete state Markov (DSM models. The DSM models are formulated in terms of the tetrameric modular structure of BK channels, consisting of a central transmembrane pore-gate domain (PGD attached to four surrounding transmembrane voltage sensing domains (VSD and a large intracellular cytosolic domain (CTD, also referred to as the gating ring. The modular structure and data analysis shows that the Ca2+ and voltage dependent gating considered separately can each be approximated by 10-state two-tiered models with 5 closed states on the upper tier and 5 open states on the lower tier. The modular structure and joint Ca2+ and voltage dependent gating are consistent with a 50 state two-tiered model with 25 closed states on the upper tier and 25 open states on the lower tier. Adding an additional tier of brief closed (flicker states to the 10-state or 50-state models improved the description of the gating. For fixed experimental conditions a channel would gate in only a subset of the potential number of states. The detected number of states and the correlations between adjacent interval durations are consistent with the tiered models. The examined models can account for the single-channel kinetics and the bursting behavior of gating. Ca2+ and voltage activate BK channels by predominantly increasing the effective opening rate of the channel with a smaller decrease in the effective closing rate. Ca2+ and depolarization thus activate by mainly destabilizing the closed states.

  18. MITOCHONDRIAL BKCa CHANNEL

    Directory of Open Access Journals (Sweden)

    Enrique eBalderas

    2015-03-01

    Full Text Available Since its discovery in a glioma cell line 15 years ago, mitochondrial BKCa channel (mitoBKCa has been studied in brain cells and cardiomyocytes sharing general biophysical properties such as high K+ conductance (~300 pS, voltage-dependency and Ca2+-sensitivity. Main advances in deciphering the molecular composition of mitoBKCa have included establishing that it is encoded by the Kcnma1 gene, that a C-terminal splice insert confers mitoBKCa ability to be targeted to cardiac mitochondria, and evidence for its potential coassembly with β subunits. Notoriously, β1 subunit directly interacts with cytochrome c oxidase and mitoBKCa can be modulated by substrates of the respiratory chain. mitoBKCa channel has a central role in protecting the heart from ischemia, where pharmacological activation of the channel impacts the generation of reactive oxygen species and mitochondrial Ca2+ preventing cell death likely by impeding uncontrolled opening of the mitochondrial transition pore. Supporting this view, inhibition of mitoBKCa with Iberiotoxin, enhances cytochrome c release from glioma mitochondria. Many tantalizing questions remain. Some of them are: how is mitoBKCa coupled to the respiratory chain? Does mitoBKCa play non-conduction roles in mitochondria physiology? Which are the functional partners of mitoBKCa? What are the roles of mitoBKCa in other cell types? Answers to these questions are essential to define the impact of mitoBKCa channel in mitochondria biology and disease.

  19. Central residual compressive stress drop on metal materials after laser induced shock wave%激光冲击波加载金属材料中心压应力缺失效应

    Institute of Scientific and Technical Information of China (English)

    王波; 陈东林; 周留成; 何卫锋

    2014-01-01

    纳秒脉冲、千兆瓦级激光辐照金属材料产生高压等离子体冲击波,作用于金属材料表面并向内传播,产生残余压应力场。但在单次冲击加载时,残余压应力场中心出现的残余压应力值小于加载边缘,应用理论分析和实验测试的方法解释了这一过程,并结合激光诱导冲击波Fabbro方程和TC4钛合金动态响应模型,建立了不同形式冲击波加载TC4钛合金的数值仿真模型,分析了冲击波压力、作用时间和加载形式对中心压应力缺失的影响。%The high pressure plasma shock wave induced by nanosecond pulse and 1 000 MW laser irradiation on the metal materials will propagate into the materials and impart residual compressive stresses. But when shock wave was singly loaded, the lower residual stress at the center of the loading zone compared to those away from the center will be induced. This process is proved by theorems and experiments. Moreover, the Fabbro equation of plasma shock wave and dynamic response of TC4 titanium alloy was calculated in the numerical model of different shock wave loading, the influence of the shock wave pressure, the actuation duration and the loading shape on residual stress drop at the center was discussed.

  20. Intracellular segment between transmembrane helices S0 and S1 of BK channel α subunit contains two amphipathic helices connected by a flexible loop.

    Science.gov (United States)

    Shi, Pan; Li, Dong; Lai, Chaohua; Zhang, Longhua; Tian, Changlin

    2013-08-02

    The BK channel, a tetrameric potassium channel with very high conductance, has a central role in numerous physiological functions. The BK channel can be activated by intracellular Ca(2+) and Mg(2+), as well as by membrane depolarization. Unlike other tetrameric potassium channels, the BK channel has seven transmembrane helices (S0-S6) including an extra helix S0. The intracellular segment between S0 and S1 (BK-IS1) is essential to BK channel functions and Asp99 in BK-IS1 is reported to be responsible for Mg(2+) coordination. In this study, BK-IS1 (44-113) was over-expressed using a bacterial system and purified in the presence of detergent micelles for multidimensional heteronuclear nuclear magnetic resonance (NMR) structural studies. Backbone resonance assignment and secondary structure analysis showed that BK-IS1 contains two amphipathic helices connected by a 36-residue loop. Amide (1)H-(15)N heteronuclear NOE analysis indicated that the loop is very flexible, while the two amphipathic helices are possibly stabilized through interaction with the membrane. A solution NMR-based titration assay of BK-IS1 was performed with various concentrations of Mg(2+). Two residues (Thr45 and Leu46) with chemical shift changes were observed but no, or very minor, chemical shift difference was observed for Asp99, indicating a possible site for binding divalent ions or other modulation partners.

  1. Sea Anemone Toxins Affecting Potassium Channels

    Science.gov (United States)

    Diochot, Sylvie; Lazdunski, Michel

    The great diversity of K+ channels and their wide distribution in many tissues are associated with important functions in cardiac and neuronal excitability that are now better understood thanks to the discovery of animal toxins. During the past few decades, sea anemones have provided a variety of toxins acting on voltage-sensitive sodium and, more recently, potassium channels. Currently there are three major structural groups of sea anemone K+ channel (SAK) toxins that have been characterized. Radioligand binding and electrophysiological experiments revealed that each group contains peptides displaying selective activities for different subfamilies of K+ channels. Short (35-37 amino acids) peptides in the group I display pore blocking effects on Kv1 channels. Molecular interactions of SAK-I toxins, important for activity and binding on Kv1 channels, implicate a spot of three conserved amino acid residues (Ser, Lys, Tyr) surrounded by other less conserved residues. Long (58-59 amino acids) SAK-II peptides display both enzymatic and K+ channel inhibitory activities. Medium size (42-43 amino acid) SAK-III peptides are gating modifiers which interact either with cardiac HERG or Kv3 channels by altering their voltage-dependent properties. SAK-III toxins bind to the S3C region in the outer vestibule of Kv channels. Sea anemones have proven to be a rich source of pharmacological tools, and some of the SAK toxins are now useful drugs for the diagnosis and treatment of autoimmune diseases.

  2. Brands & Channels

    Institute of Scientific and Technical Information of China (English)

    Alice Yang

    2009-01-01

    @@ "Brands" and "Channels" are the two most important things in Ku-Hai Chen's eyes when doing business with Main-land China. Ku-Hai Chen, Executive Director of the International Trade Institute of Taiwan External Trade Development Council (TAITRA), flies frequently between Chinese Taipei and Mainland China, and was in Beijing earlier this month for his seminar.

  3. Positron Channeling

    CERN Document Server

    Badikyan, Karen

    2016-01-01

    The possibility of channeling the low-energy relativistic positrons around separate crystallographic axes with coaxial symmetry of negative ions in some types of crystals is shown. The process of annihilation of positrons with electrons of medium was studied in detail.

  4. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

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

    2004-01-01

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

  5. Homologue Structure of the SLAC1 Anion Channel for Closing Stomata in Leaves

    Energy Technology Data Exchange (ETDEWEB)

    Y Chen; L Hu; M Punta; R Bruni; B Hillerich; B Kloss; B Rost; J Love; S Siegelbaum; W Hendrickson

    2011-12-31

    The plant SLAC1 anion channel controls turgor pressure in the aperture-defining guard cells of plant stomata, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought or high levels of carbon dioxide. Here we determine the crystal structure of a bacterial homologue (Haemophilus influenzae) of SLAC1 at 1.20 {angstrom} resolution, and use structure-inspired mutagenesis to analyse the conductance properties of SLAC1 channels. SLAC1 is a symmetrical trimer composed from quasi-symmetrical subunits, each having ten transmembrane helices arranged from helical hairpin pairs to form a central five-helix transmembrane pore that is gated by an extremely conserved phenylalanine residue. Conformational features indicate a mechanism for control of gating by kinase activation, and electrostatic features of the pore coupled with electrophysiological characteristics indicate that selectivity among different anions is largely a function of the energetic cost of ion dehydration.

  6. Nonlinear channelizer

    Science.gov (United States)

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

    2012-12-01

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

  7. Modulation of Ionotropic Glutamate Receptors and Acid-Sensing Ion Channels by Nitric Oxide

    Directory of Open Access Journals (Sweden)

    John Q Wang

    2012-05-01

    Full Text Available Ionotropic glutamate receptors (iGluR are ligand-gated ion channels and are densely expressed in broad areas of mammalian brains. Like iGluRs, acid-sensing ion channels (ASIC are ligand (H+-gated channels and are enriched in brain cells and peripheral sensory neurons. Both ion channels are enriched at excitatory synaptic sites, functionally coupled to each other, and subject to the modulation by a variety of signaling molecules. Central among them is a gasotransmitter, nitric oxide (NO. Available data show that NO activity-dependently modulates iGluRs and ASICs via either a direct or an indirect pathway. The former involves a NO-based and cGMP-independent posttranslational modification (S-nitrosylation of extracellular cysteine residues in channel subunits or channel-interacting proteins. The latter is achieved by NO activation of soluble guanylyl cyclase, which in turn triggers an intracellular cGMP-sensitive cascade to indirectly modulate iGluRs and ASICs. The NO modification is usually dynamic and reversible. Modified channels undergo significant, interrelated changes in biochemistry and electrophysiology. Since NO synthesis is enhanced in various neurological disorders, the NO modulation of iGluRs and ASICs is believed to be directly linked to the pathogenesis of these disorders. This review summarizes the direct and indirect modifications of iGluRs and ASICs by NO and analyzes the role of the NO-iGluR and NO-ASIC coupling in cell signaling and in the pathogenesis of certain related neurological diseases.

  8. Deployable centralizers

    Energy Technology Data Exchange (ETDEWEB)

    Grubelich, Mark C.; Su, Jiann-Cherng; Knudsen, Steven D.

    2017-02-28

    A centralizer assembly is disclosed that allows for the assembly to be deployed in-situ. The centralizer assembly includes flexible members that can be extended into the well bore in situ by the initiation of a gas generating device. The centralizer assembly can support a large load carrying capability compared to a traditional bow spring with little or no installation drag. Additionally, larger displacements can be produced to centralize an extremely deviated casing.

  9. Analysis of the action of lidocaine on insect sodium channels.

    Science.gov (United States)

    Song, Weizhong; Silver, Kristopher S; Du, Yuzhe; Liu, Zhiqi; Dong, Ke

    2011-01-01

    A new class of sodium channel blocker insecticides (SCBIs), which include indoxacarb, its active metabolite, DCJW, and metaflumizone, preferably block inactivated states of both insect and mammalian sodium channels in a manner similar to that by which local anesthetic (LA) drugs block mammalian sodium channels. A recent study showed that two residues in the cockroach sodium channel, F1817 and Y1824, corresponding to two key LA-interacting residues identified in mammalian sodium channels are not important for the action of SCBIs on insect sodium channels, suggesting unique interactions of SCBIs with insect sodium channels. However, the mechanism of action of LAs on insect sodium channels has not been investigated. In this study, we examined the effects of lidocaine on a cockroach sodium channel variant, BgNa(v)1-1a, and determined whether F1817 and Y1824 are also critical for the action of LAs on insect sodium channels. Lidocaine blocked BgNa(v)1-1a channels in the resting state with potency similar to that observed in mammalian sodium channels. Lidocaine also stabilized both fast-inactivated and slow-inactivated states of BgNa(v)1-1a channels, and caused a limited degree of use- and frequency-dependent block, major characteristics of LA action on mammalian sodium channels. Alanine substitutions of F1817 and Y1824 reduced the sensitivity of the BgNa(v)1-1a channel to the use-dependent block by lidocaine, but not to tonic blocking and inactivation stabilizing effects of lidocaine. Thus, similar to those on mammalian sodium channels, F1817 and Y1824 are important for the action of lidocaine on cockroach sodium channels. Our results suggest that the receptor sites for lidocaine and SCBIs are different on insect sodium channels.

  10. NALCN ion channels have alternative selectivity filters resembling calcium channels or sodium channels.

    Directory of Open Access Journals (Sweden)

    Adriano Senatore

    Full Text Available NALCN is a member of the family of ion channels with four homologous, repeat domains that include voltage-gated calcium and sodium channels. NALCN is a highly conserved gene from simple, extant multicellular organisms without nervous systems such as sponges and placozoans and mostly remains a single gene compared to the calcium and sodium channels which diversified into twenty genes in humans. The single NALCN gene has alternatively-spliced exons at exons 15 or exon 31 that splices in novel selectivity filter residues that resemble calcium channels (EEEE or sodium channels (EKEE or EEKE. NALCN channels with alternative calcium, (EEEE and sodium, (EKEE or EEKE -selective pores are conserved in simple bilaterally symmetrical animals like flatworms to non-chordate deuterostomes. The single NALCN gene is limited as a sodium channel with a lysine (K-containing pore in vertebrates, but originally NALCN was a calcium-like channel, and evolved to operate as both a calcium channel and sodium channel for different roles in many invertebrates. Expression patterns of NALCN-EKEE in pond snail, Lymnaea stagnalis suggest roles for NALCN in secretion, with an abundant expression in brain, and an up-regulation in secretory organs of sexually-mature adults such as albumen gland and prostate. NALCN-EEEE is equally abundant as NALCN-EKEE in snails, but is greater expressed in heart and other muscle tissue, and 50% less expressed in the brain than NALCN-EKEE. Transfected snail NALCN-EEEE and NALCN-EKEE channel isoforms express in HEK-293T cells. We were not able to distinguish potential NALCN currents from background, non-selective leak conductances in HEK293T cells. Native leak currents without expressing NALCN genes in HEK-293T cells are NMDG(+ impermeant and blockable with 10 µM Gd(3+ ions and are indistinguishable from the hallmark currents ascribed to mammalian NALCN currents expressed in vitro by Lu et al. in Cell. 2007 Apr 20;129(2:371-83.

  11. Optimized Combination of Residue Hydrodesulfurization and Residue Fluid Catalytic Cracking

    Institute of Scientific and Technical Information of China (English)

    Chen Junwu

    2003-01-01

    @@1 Introduction Combination of residue hydrodesulfurization (HDS) and resi-due fluid catalytic cracking (RFCC) is a unique technologyfor processing high-sulfur residue. This paper discusses theoptimized combination of these two processes.

  12. An ERG channel inhibitor from the scorpion Buthus eupeus

    DEFF Research Database (Denmark)

    Korolkova, Y.V.; Kozlov, S.A.; Lipkin, A.V.

    2001-01-01

    The isolation of the peptide inhibitor of M-type K(+) current, BeKm-1, from the venom of the Central Asian scorpion Buthus eupeus has been described previously (Fillipov A. K., Kozlov, S. A., Pluzhnikov, K. A., Grishin, E. V., and Brown, D. A. (1996) FEBS Lett. 384, 277-280). Here we report...... the cloning, expression, and selectivity of BeKm-1. A full-length cDNA of 365 nucleotides encoding the precursor of BeKm-1 was isolated using the rapid amplification of cDNA ends polymerase chain reaction technique from mRNA obtained from scorpion telsons. Sequence analysis of the cDNA revealed...... that the precursor contains a signal peptide of 21 amino acid residues. The mature toxin consists of 36 amino acid residues. BeKm-1 belongs to the family of scorpion venom potassium channel blockers and represents a new subgroup of these toxins. The recombinant BeKm-1 was produced as a Protein A fusion product...

  13. Binding site residues control inhibitor selectivity in the human norepinephrine transporter but not in the human dopamine transporter

    DEFF Research Database (Denmark)

    Andersen, Jacob; Ringsted, Kristoffer B; Bang-Andersen, Benny

    2015-01-01

    . Changing the six diverging residues in the central binding site of NET to the complementary residues in DAT transferred a DAT-like pharmacology to NET, showing that non-conserved binding site residues in NET are critical determinants for inhibitor selectivity. In contrast, changing the equivalent residues...

  14. Modelling pesticides residues

    OpenAIRE

    2004-01-01

    This work is a contribution to the development of a specific method to assess the presence of residues in agricultural commodities. The following objectives are formulated: to identify and describe main processes in environment — plant exchanges, to build of a model to assess the residue concentration at harvest in agricultural commodities, to understand the functioning of the modelled system, to characterise pesticides used in field crops and identify optimisation potentials in phytosanitary...

  15. CENTRAL PLATEAU REMEDIATION

    Energy Technology Data Exchange (ETDEWEB)

    ROMINE, L.D.

    2006-02-01

    A systematic approach to closure planning is being implemented at the Hanford Site's Central Plateau to help achieve the goal of closure by the year 2035. The overall objective of Central Plateau remediation is to protect human health and the environment from the significant quantity of contaminated material that resulted from decades of plutonium production in support of the nation's defense. This goal will be achieved either by removing contaminants or placing the residual contaminated materials in a secure configuration that minimizes further migration to the groundwater and reduces the potential for inadvertent intrusion into contaminated sites. The approach to Central Plateau cleanup used three key concepts--closure zones, closure elements, and closure process steps--to create an organized picture of actions required to complete remediation. These actions were merged with logic ties, constraints, and required resources to produce an integrated time-phased schedule and cost profile for Central Plateau closure. Programmatic risks associated with implementation of Central Plateau closure were identified and analyzed. Actions to mitigate the most significant risks are underway while high priority remediation projects continue to make progress.

  16. FIR Filter Implementation Based on the RNS with Diminished-1 Encoded Channel

    Directory of Open Access Journals (Sweden)

    Dragana Uros Zivaljevic

    2013-03-01

    Full Text Available A technique, based on the residue number system (RNS with diminished-1 encoded channel, has being used for implementing a finite impulse response (FIR digital filter. The proposed RNS architecture of the filter consists of three main blocks: forward and reverse converter and arithmetic processor for each channel. Architecture for residue to binary (reverse convertor with diminished-1 encoded channel has been proposed. Besides, for all RNS channels, the systolic design is used for the efficient  realization of FIR filter. A numerical example illustrates the principles of diminished-1 residue arithmetic, signal processing, and decoding for FIR filters.

  17. VKCDB: Voltage-gated potassium channel database

    Directory of Open Access Journals (Sweden)

    Gallin Warren J

    2004-01-01

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

  18. Acid-Sensing Ion Channels and Pain

    Directory of Open Access Journals (Sweden)

    Qihai Gu

    2010-05-01

    Full Text Available Pathophysiological conditions such as inflammation, ischemia, infection and tissue injury can all evoke pain, and each is accompanied by local acidosis. Acid sensing ion channels (ASICs are proton-gated cation channels expressed in both central and peripheral nervous systems. Increasing evidence suggests that ASICs represent essential sensors for tissue acidosis-related pain. This review provides an update on the role of ASICs in pain sensation and discusses their therapeutic potential for pain management.

  19. Forest Management Effects on Channel Wood and Wood-Channel Interactions in Caspar Creek, California

    Science.gov (United States)

    Hilton, S.

    2006-12-01

    First-cycle logging in much of California's redwood region converted streams with some of the highest known wood volumes and piece sizes to efficient log transport channels. A century later, second-growth trees are still much smaller than old growth, and later logging and stream cleaning have further affected potential wood inputs and large woody debris (LWD) volumes in channels. At Caspar Creek, a 50-year paired watershed study creates an opportunity to compare the effects of two second-growth forest management strategies on wood dynamics in these channels, and to examine how the resulting differences in LWD affect channel form and process. Both the North and South Forks of Caspar Creek started the 20th century with almost no in-channel wood and little potential LWD as a result of clearcut logging, burning, and channel clearing. Stands had partially regrown by 1968, when near-channel roadbuilding and selective logging in the 424-ha South Fork watershed again reduced potential channel LWD. Trees that fell into the channel during logging were removed, along with some instream wood. Logging began in the 384-ha North Fork in 1989 using ridgetop roads; buffer strips were left between the mainstem channel and upslope clearcuts. Potential LWD in the buffer strips was reduced by selective cutting, but channel LWD was not immediately affected. LWD mapping, inventories, and tagging, channel cross-sections and photos, and pool mapping and volume measurements show differences in channel wood and LWD-channel interactions between the two watersheds. Windthrow from buffer strips increased the total channel LWD volume in the North Fork in the mid 1990's while reducing potential future LWD. These higher LWD loads increased pool volumes and enabled increased sediment storage, particularly upstream of logjams. In the South Fork, total LWD volumes are lower and a higher proportion of the wood is residual old growth pieces, some of which entered the channel during the 1970's logging

  20. Resolving the 3D spatial orientation of helix I in the closed state of the colicin E1 channel domain by FRET. Insights into the integration mechanism.

    Science.gov (United States)

    Lugo, Miguel R; Ho, Derek; Merrill, A Rod

    2016-10-15

    Current evidence suggests that the closed-state membrane model for the channel-forming domain of colicin E1 involves eight amphipathic α-helices (helices I-VII and X) that adopt a two-dimensional arrangement on the membrane surface. Two central hydrophobic α-helices in colicin E1 (VIII and IX) adopt a transmembrane location-the umbrella model. Helices I and II have been shown to participate in the channel by forming a transmembrane segment (TM1) in the voltage-induced open channel state. Consequently, it is paramount to determine the relative location and orientation of helix I in the two-dimensional arrangement of the membrane. A new, low-resolution, three-dimensional model of the closed state of the colicin E1 channel was constructed based on FRET measurements between three naturally occurring Trp residues and three sites in helix I, in addition to previously reported FRET distances for the channel domain. Furthermore, a new mechanism for the channel integration process involving the transition of the soluble to membrane-bound form is presented based on a plethora of kinetic data for this process.

  1. Charges in the cytoplasmic pore control intrinsic inward rectification and single-channel properties in Kir1.1 and Kir2.1 channels.

    Science.gov (United States)

    Chang, Hsueh-Kai; Yeh, Shih-Hao; Shieh, Ru-Chi

    2007-02-01

    An E224G mutation of the Kir2.1 channel generates intrinsic inward rectification and single-channel fluctuations in the absence of intracellular blockers. In this study, we showed that positively charged residues H226, R228 and R260, near site 224, regulated the intrinsic inward rectification and single-channel properties of the E224G mutant. By carrying out systematic mutations, we found that the charge effect on the intrinsic inward rectification and single-channel conductance is consistent with a long-range electrostatic mechanism. A Kir1.1 channel where the site equivalent to E224 in the Kir2.1 channel is a glycine residue does not show inward rectification or single-channel fluctuations. The G223K and N259R mutations of the Kir1.1 channel induced intrinsic inward rectification and reduced the single-channel conductance but did not generate large open-channel fluctuations. Substituting the cytoplasmic pore of the E224G mutant into the Kir1.1 channel induced open-channel fluctuations and intrinsic inward rectification. The single-channel conductance of the E224G mutant showed inward rectification. Also, a voltage-dependent gating mechanism decreased open probability during depolarization and contributed to the intrinsic inward rectification in the E224G mutant. In addition to an electrostatic effect, a close interaction of K(+) with channel pore may be required for generating open-channel fluctuations in the E224G mutant.

  2. Covariant Residual Entropy

    CERN Document Server

    Hubeny, Veronika E

    2014-01-01

    A recently explored interesting quantity in AdS/CFT, dubbed 'residual entropy', characterizes the amount of collective ignorance associated with either boundary observers restricted to finite time duration, or bulk observers who lack access to a certain spacetime region. However, the previously-proposed expression for this quantity involving variation of boundary entanglement entropy (subsequently renamed to 'differential entropy') works only in a severely restrictive context. We explain the key limitations, arguing that in general, differential entropy does not correspond to residual entropy. Given that the concept of residual entropy as collective ignorance transcends these limitations, we identify two correspondingly robust, covariantly-defined constructs: a 'strip wedge' associated with boundary observers and a 'rim wedge' associated with bulk observers. These causal sets are well-defined in arbitrary time-dependent asymptotically AdS spacetimes in any number of dimensions. We discuss their relation, spec...

  3. A ligand channel through the G protein coupled receptor opsin.

    Directory of Open Access Journals (Sweden)

    Peter W Hildebrand

    Full Text Available The G protein coupled receptor rhodopsin contains a pocket within its seven-transmembrane helix (TM structure, which bears the inactivating 11-cis-retinal bound by a protonated Schiff-base to Lys296 in TM7. Light-induced 11-cis-/all-trans-isomerization leads to the Schiff-base deprotonated active Meta II intermediate. With Meta II decay, the Schiff-base bond is hydrolyzed, all-trans-retinal is released from the pocket, and the apoprotein opsin reloaded with new 11-cis-retinal. The crystal structure of opsin in its active Ops* conformation provides the basis for computational modeling of retinal release and uptake. The ligand-free 7TM bundle of opsin opens into the hydrophobic membrane layer through openings A (between TM1 and 7, and B (between TM5 and 6, respectively. Using skeleton search and molecular docking, we find a continuous channel through the protein that connects these two openings and comprises in its central part the retinal binding pocket. The channel traverses the receptor over a distance of ca. 70 A and is between 11.6 and 3.2 A wide. Both openings are lined with aromatic residues, while the central part is highly polar. Four constrictions within the channel are so narrow that they must stretch to allow passage of the retinal beta-ionone-ring. Constrictions are at openings A and B, respectively, and at Trp265 and Lys296 within the retinal pocket. The lysine enforces a 90 degrees elbow-like kink in the channel which limits retinal passage. With a favorable Lys side chain conformation, 11-cis-retinal can take the turn, whereas passage of the all-trans isomer would require more global conformational changes. We discuss possible scenarios for the uptake of 11-cis- and release of all-trans-retinal. If the uptake gate of 11-cis-retinal is assigned to opening B, all-trans is likely to leave through the same gate. The unidirectional passage proposed previously requires uptake of 11-cis-retinal through A and release of photolyzed all

  4. Sharing Residual Liability

    DEFF Research Database (Denmark)

    Carbonara, Emanuela; Guerra, Alice; Parisi, Francesco

    2016-01-01

    Economic models of tort law evaluate the efficiency of liability rules in terms of care and activity levels. A liability regime is optimal when it creates incentives to maximize the value of risky activities net of accident and precaution costs. The allocation of primary and residual liability...... allows policy makers to induce parties to undertake socially desirable care and activity levels. Traditionally, tort law systems have assigned residual liability either entirely on the tortfeasor or entirely on the victim. In this paper, we unpack the cheapest-cost-avoider principle to consider...

  5. Decomposition of residue currents

    OpenAIRE

    Andersson, Mats; Wulcan, Elizabeth

    2007-01-01

    Given a submodule $J\\subset \\mathcal O_0^{\\oplus r}$ and a free resolution of $J$ one can define a certain vector valued residue current whose annihilator is $J$. We make a decomposition of the current with respect to Ass$(J)$ that correspond to a primary decomposition of $J$. As a tool we introduce a class of currents that includes usual residue and principal value currents; in particular these currents admit a certain type of restriction to analytic varieties and more generally to construct...

  6. Residual-stress measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ezeilo, A.N.; Webster, G.A. [Imperial College, London (United Kingdom); Webster, P.J. [Salford Univ. (United Kingdom)

    1997-04-01

    Because neutrons can penetrate distances of up to 50 mm in most engineering materials, this makes them unique for establishing residual-stress distributions non-destructively. D1A is particularly suited for through-surface measurements as it does not suffer from instrumental surface aberrations commonly found on multidetector instruments, while D20 is best for fast internal-strain scanning. Two examples for residual-stress measurements in a shot-peened material, and in a weld are presented to demonstrate the attractive features of both instruments. (author).

  7. The central mechanism underlying hypertension: a review of the roles of sodium ions, epithelial sodium channels, the renin–angiotensin–aldosterone system, oxidative stress and endogenous digitalis in the brain

    OpenAIRE

    2011-01-01

    The central nervous system has a key role in regulating the circulatory system by modulating the sympathetic and parasympathetic nervous systems, pituitary hormone release, and the baroreceptor reflex. Digoxin- and ouabain-like immunoreactive materials were found >20 years ago in the hypothalamic nuclei. These factors appeared to localize to the paraventricular and supraoptic nuclei and the nerve fibers at the circumventricular organs and supposed to affect electrolyte balance and blood press...

  8. The Origins of Transmembrane Ion Channels

    Science.gov (United States)

    Pohorille, Andrew; Wilson, Michael A.

    2012-01-01

    Even though membrane proteins that mediate transport of ions and small molecules across cell walls are among the largest and least understood biopolymers in contemporary cells, it is still possible to shed light on their origins and early evolution. The central observation is that transmembrane portions of most ion channels are simply bundles of -helices. By combining results of experimental and computer simulation studies on synthetic models and natural channels, mostly of non-genomic origin, we show that the emergence of -helical channels was protobiologically plausible, and did not require highly specific amino acid sequences. Despite their simple structure, such channels could possess properties that, at the first sight, appear to require markedly larger complexity. Specifically, we explain how the antiamoebin channels, which are made of identical helices, 16 amino acids in length, achieve efficiency comparable to that of highly evolved channels. We further show that antiamoebin channels are extremely flexible, compared to modern, genetically coded channels. On the basis of our results, we propose that channels evolved further towards high structural complexity because they needed to acquire stable rigid structures and mechanisms for precise regulation rather than improve efficiency. In general, even though architectures of membrane proteins are not nearly as diverse as those of water-soluble proteins, they are sufficiently flexible to adapt readily to the functional demands arising during evolution.

  9. Ion channels regulating mast cell biology.

    Science.gov (United States)

    Ashmole, I; Bradding, P

    2013-05-01

    Mast cells play a central role in the pathophysiology of asthma and related allergic conditions. Mast cell activation leads to the degranulation of preformed mediators such as histamine and the secretion of newly synthesised proinflammatory mediators such as leukotrienes and cytokines. Excess release of these mediators contributes to allergic disease states. An influx of extracellular Ca2+ is essential for mast cell mediator release. From the Ca2+ channels that mediate this influx, to the K+ , Cl- and transient receptor potential channels that set the cell membrane potential and regulate Ca2+ influx, ion channels play a critical role in mast cell biology. In this review we provide an overview of our current knowledge of ion channel expression and function in mast cells with an emphasis on how channels interact to regulate Ca2+ signalling.

  10. Residual stresses within sprayed coatings

    Institute of Scientific and Technical Information of China (English)

    JIANG Yi; XU Bin-shi; WANG Hai-dou

    2005-01-01

    Some important developments of residual stress researches for coating-based systems were studied. The following topics were included the sources of residual stresses in coatings: error analysis of Stoney's equation in the curvature method used for the measurement of coating residual stress, the modeling of residual stress and some analytical models for predicting the residual stresses in coatings. These topics should provide some important insights for the fail-safe design of the coating-based systems.

  11. Ferritin ion channel disorder inhibits Fe(II)/O2 reactivity at distant sites.

    Science.gov (United States)

    Tosha, Takehiko; Behera, Rabindra K; Theil, Elizabeth C

    2012-11-05

    Ferritins, a complex, mineralized, protein nanocage family essential for life, provide iron concentrates and oxidant protection. Protein-based ion channels and Fe(II)/O(2) catalysis initiate conversion of thousands of Fe atoms to caged, ferritin Fe(2)O(3)·H(2)O minerals. The ion channels consist of six helical segments, contributed by 3 of 12 or 24 polypeptide subunits, around the 3-fold cage axes. The channel structure guides entering Fe(II) ions toward multiple, catalytic, diiron sites buried inside ferritin protein helices, ~20 Å away from channel internal exits. The catalytic product, Fe(III)-O(H)-Fe(III), is a mineral precursor; mineral nucleation begins inside the protein cage with mineral growth in the central protein cavity (5-8 nm diameter). Amino acid substitutions that changed ionic or hydrophobic channel interactions R72D, D122R, and L134P increased ion channel structural disorder (protein crystallographic analyses) and increased Fe(II) exit [chelated Fe(II) after ferric mineral reduction/dissolution]. Since substitutions of some channel carboxylate residues diminished ferritin catalysis with no effect on Fe(II) exit, such as E130A and D127A, we investigated catalysis in ferritins with altered Fe(II) exit, R72D, D122R and L134P. The results indicate that simply changing the ionic properties of the channels, as in the R72D variant, need not change the forward catalytic rate. However, both D122R and L134P, which had dramatic effects on ferritin catalysis, also caused larger effects on channel structure and order, contrasting with R72D. All three amino acid substitutions, however, decreased the stability of the catalytic intermediate, diferric peroxo, even though overall ferritin cage structure is very stable, resisting 80 °C and 6 M urea. The localized structural changes in ferritin subdomains that affect ferritin function over long distances illustrate new properties of the protein cage in natural ferritin function and for applied ferritin uses.

  12. Mobile radio channels

    CERN Document Server

    Pätzold, Matthias

    2011-01-01

    Providing a comprehensive overview of the modelling, analysis and simulation of mobile radio channels, this book gives a detailed understanding of fundamental issues and examines state-of-the-art techniques in mobile radio channel modelling. It analyses several mobile fading channels, including terrestrial and satellite flat-fading channels, various types of wideband channels and advanced MIMO channels, providing a fundamental understanding of the issues currently being investigated in the field. Important classes of narrowband, wideband, and space-time wireless channels are explored in deta

  13. Channel nut tool

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Marvin

    2016-01-12

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

  14. Major Channels Involved In Neuropsychiatric Disorders And Therapeutic Perspectives

    Directory of Open Access Journals (Sweden)

    Paola eImbrici

    2013-05-01

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

  15. Human sperm cells swimming in micro-channels

    CERN Document Server

    Denissenko, Petr; Smith, David; Kirkman-Brown, Jackson

    2012-01-01

    The migratory abilities of motile human spermatozoa in vivo are essential for natural fertility, but it remains a mystery what properties distinguish the tens of cells which find an egg from the millions of cells ejaculated. To reach the site of fertilization, sperm must traverse narrow and convoluted channels, filled with viscous fluids. To elucidate individual and group behaviors that may occur in the complex three-dimensional female tract environment, we examine the behavior of migrating sperm in assorted micro-channel geometries. Cells rarely swim in the central part of the channel cross-section, instead traveling along the intersection of the channel walls (`channel corners'). When the channel turns sharply, cells leave the corner, continuing ahead until hitting the opposite wall of the channel, with a distribution of departure angles, the latter being modulated by fluid viscosity. If the channel bend is smooth, cells depart from the inner wall when the curvature radius is less than a threshold value clo...

  16. Vascular potassium channels in NVC.

    Science.gov (United States)

    Yamada, K

    2016-01-01

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

  17. Functional diversity and evolutionary dynamics of thermoTRP channels.

    Science.gov (United States)

    Saito, Shigeru; Tominaga, Makoto

    2015-03-01

    Animals have evolved sophisticated physiological systems for sensing ambient temperature since changes in environmental temperatures affect various biological processes. Thermosensitive transient receptor potential (thermoTRP) channels serve as thermal sensors in diverse animal species. They are multimodal receptors that are activated by temperature as well as other physical and chemical stimuli. Since thermoTRP channels are calcium permeable non-selective cation channels, their activation leads to an influx of calcium and sodium ions into the cell and triggers downstream signal transduction. ThermoTRP channels have been characterized in diverse animal species over the past several years, illuminating the diversification of thermoTRP channels in the course of evolution. The gene repertoires of thermoTRP channels differ among animal species. Additionally, in some cases, the temperature and chemical sensitivities among orthologous thermoTRP channels vary among species. The evolutionary flexibility of thermoTRP channels enabled them to contribute to unique physiological systems such as infrared sensation in snakes and bats and seasonal adaptation in silk moth. On the other hand, the functional differences of thermoTRP channels among species have been utilized for understanding the molecular basis for their activation (or inhibition) mechanisms, and amino acid residues (or domains) responsible for the respective channel properties have been identified in various thermoTRP channels. Here we summarize the current understanding of the functional diversity and evolutionary dynamics of thermoTRP channels.

  18. Studies of alpha-helicity and intersegmental interactions in voltage-gated Na+ channels: S2D4.

    Directory of Open Access Journals (Sweden)

    Zhongming Ma

    Full Text Available Much data, including crystallographic, support structural models of sodium and potassium channels consisting of S1-S4 transmembrane segments (the "voltage-sensing domain" clustered around a central pore-forming region (S5-S6 segments and the intervening loop. Voltage gated sodium channels have four non-identical domains which differentiates them from the homotetrameric potassium channels that form the basis for current structural models. Since potassium and sodium channels also exhibit many different functional characteristics and the fourth domain (D4 of sodium channels differs in function from other domains (D1-D3, we have explored its structure in order to determine whether segments in D4 of sodium channels differ significantly from that determined for potassium channels. We have probed the secondary and tertiary structure and the role of the individual amino acid residues of the S2D4 of Na(v1.4 by employing cysteine-scanning mutagenesis (with tryptophan and glutamine substituted for native cysteine. A Fourier transform power spectrum of perturbations in free energy of steady-state inactivation gating (using midpoint potentials and slopes of Boltzmann equation fits of channel availability, h(infinity-V plots indicates a substantial amount of alpha-helical structure in S2D4 (peak at 106 degrees, alpha-Periodicity Index (alpha-PI of 3.10, This conclusion is supported by alpha-PI values of 3.28 and 2.84 for the perturbations in rate constants of entry into (beta and exit from (alpha fast inactivation at 0 mV for mutant channels relative to WT channels assuming a simple two-state model for transition from the open to inactivated state. The results of cysteine substitution at the two most sensitive sites of the S2D4 alpha-helix (N1382 and E1392C support the existence of electrostatic network interactions between S2 and other transmembrane segments within Na(v1.4D4 similar to but not identical to those proposed for K+ channels.

  19. Observer's observables. Residual diffeomorphisms

    CERN Document Server

    Duch, Paweł; Świeżewski, Jedrzej

    2016-01-01

    We investigate the fate of diffeomorphisms when the radial gauge is imposed in canonical general relativity. As shown elsewhere, the radial gauge is closely related to the observer's observables. These observables are invariant under a large subgroup of diffeomorphisms which results in their usefulness for canonical general relativity. There are, however, some diffeomorphisms, called residual diffeomorphisms, which might be "observed" by the observer as they do not preserve her observables. The present paper is devoted to the analysis of these diffeomorphisms in the case of the spatial and spacetime radial gauges. Although the residual diffeomorphisms do not form a subgroup of all diffeomorphisms, we show that their induced action in the phase space does form a group. We find the generators of the induced transformations and compute the structure functions of the algebras they form. The obtained algebras are deformations of the algebra of the Euclidean group and the algebra of the Poincar\\'e group in the spat...

  20. Structural basis of dual Ca(2+)/pH regulation of the endolysosomal TRPML1 channel.

    Science.gov (United States)

    Li, Minghui; Zhang, Wei K; Benvin, Nicole M; Zhou, Xiaoyuan; Su, Deyuan; Li, Huan; Wang, Shu; Michailidis, Ioannis E; Tong, Liang; Li, Xueming; Yang, Jian

    2017-01-23

    The activities of organellar ion channels are often regulated by Ca(2+) and H(+), which are present in high concentrations in many organelles. Here we report a structural element critical for dual Ca(2+)/pH regulation of TRPML1, a Ca(2+)-release channel crucial for endolysosomal function. TRPML1 mutations cause mucolipidosis type IV (MLIV), a severe lysosomal storage disorder characterized by neurodegeneration, mental retardation and blindness. We obtained crystal structures of the 213-residue luminal domain of human TRPML1 containing three missense MLIV-causing mutations. This domain forms a tetramer with a highly electronegative central pore formed by a novel luminal pore loop. Cysteine cross-linking and cryo-EM analyses confirmed that this architecture occurs in the full-length channel. Structure-function studies demonstrated that Ca(2+) and H(+) interact with the luminal pore and exert physiologically important regulation. The MLIV-causing mutations disrupt the luminal-domain structure and cause TRPML1 mislocalization. Our study reveals the structural underpinnings of TRPML1's regulation, assembly and pathogenesis.

  1. Calmodulin modulation of ion channels and receptors

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ion channels and receptors are the structural basis for neural signaling and transmission. Recently, the function of ion channels and receptors has been demonstrated to be modulated by many intracellular and extracellular chemicals and signaling molecules. Increasing evidence indicates that the complexity and plasticity of the function of central nervous system is determined by the modulation of ion channels and receptors. Among various mechanisms, Ca 2+ signaling pathways play important roles in neuronal activity and some pathological changes. Ca 2+ influx through ion channels and receptors can modulate its further influx in a feedback way or modulate other ion channels and receptors. The common feature of the modulation is that Ca 2+ /calmodulin (CaM) is the universal mediator. CaM maintains the coordination among ion channels/receptors and intracellular Ca 2+ homeostasis by feedback modulation of ion channels/receptors activity. This review focuses on the modulating processes of ion channels and receptors mediated by CaM, and further elucidates the mechanisms of Ca 2+ signaling.

  2. Quantum Correlations Evolution Asymmetry in Quantum Channels

    Science.gov (United States)

    Li, Meng; Huang, Yun-Feng; Guo, Guang-Can

    2017-03-01

    It was demonstrated that the entanglement evolution of a specially designed quantum state in the bistochastic channel is asymmetric. In this work, we generalize the study of the quantum correlations, including entanglement and quantum discord, evolution asymmetry to various quantum channels. We found that the asymmetry of entanglement and quantum discord only occurs in some special quantum channels, and the behavior of the entanglement evolution may be quite different from the behavior of the quantum discord evolution. To quantum entanglement, in some channels it decreases monotonously with the increase of the quantum channel intensity. In some other channels, when we increase the intensity of the quantum channel, it decreases at first, then keeps zero for some time, and then rises up. To quantum discord, the evolution becomes more complex and you may find that it evolutes unsmoothly at some points. These results illustrate the strong dependence of the quantum correlations evolution on the property of the quantum channels. Supported by the National Natural Science Foundation of China under Grant Nos. 61327901, 61490711, 61225025, 11474268, and the Fundamental Research Funds for the Central Universities under Grant No. WK2470000018

  3. Cooperative Feedback for MIMO Interference Channels

    CERN Document Server

    Huang, Kaibin

    2010-01-01

    Multi-antenna precoding effectively mitigates the interference in wireless networks. However, the precoding efficiency can be significantly degraded by the overhead due to the required feedback of channel state information (CSI). This paper addresses such an issue by proposing a systematic method of designing precoders for the two-user multiple-input-multiple-output (MIMO) interference channels based on finite-rate CSI feedback from receivers to their interferers, called cooperative feedback. Specifically, each precoder is decomposed into inner and outer precoders for nulling interference and improving the data link array gain, respectively. The inner precoders are further designed to suppress residual interference resulting from finite-rate cooperative feedback. To regulate residual interference due to precoder quantization, additional scalar cooperative feedback signals are designed to control transmitters' power using different criteria including applying interference margins, maximizing sum throughput, an...

  4. Residual contaminants in milk

    Directory of Open Access Journals (Sweden)

    Nevijo Zdolec

    2006-07-01

    Full Text Available Various chemical agents are used during the whole production chain of milk and dairy products. Production of feedingstuffs is accompanied with pesticide usage, which may remain in environment, thus are transported through feeding into animals, animal products and finally in human organism. Preparation procedure and storage conditions of feed also influence on milk safety in the sense of mycotoxins entering into the food chain. Chemical agents are, on daily basis, used on dairy farms either as detergents or disinfections. The residuals of cleaning agents might remain in milk if the cleaning agents and its dosage are not performed adequately. Besides already mentioned agents, a great influence in milk production can bee seen through veterinary drugs usage, particularly antibacterial drugs (mastitis. Proper application of drugs and by following legal recommendation, a by-reactions can be avoided such as allergic reaction in humans, development of resisting bacteria or even undesirable influence on starter cultures in dairy products manufacture. The maximum residue limits, monitoring plan as well as sampling procedures are set up within the harmonization of Croatian and European legislation, in order to provide official control of residues in foodstuffs of animal origin.

  5. Complexes of Peptide Blockers with Kv1.6 Pore Domain: Molecular Modeling and Studies with KcsA-Kv1.6 Channel.

    Science.gov (United States)

    Nekrasova, O V; Volyntseva, A D; Kudryashova, K S; Novoseletsky, V N; Lyapina, E A; Illarionova, A V; Yakimov, S A; Korolkova, Yu V; Shaitan, K V; Kirpichnikov, M P; Feofanov, A V

    2016-09-17

    Potassium voltage-gated Kv1.6 channel, which is distributed primarily in neurons of central and peripheral nervous systems, is of significant physiological importance. To date, several high-affinity Kv1.6-channel blockers are known, but the lack of selective ones among them hampers the studies of tissue localization and functioning of Kv1.6 channels. Here we present an approach to advanced understanding of interactions of peptide toxin blockers with a Kv1.6 pore. It combines molecular modeling studies and an application of a new bioengineering system based on a KcsA-Kv1.6 hybrid channel for the quantitative fluorescent analysis of blocker-channel interactions. Using this system we demonstrate that peptide toxins agitoxin 2, kaliotoxin1 and OSK1 have similar high affinity to the extracellular vestibule of the K(+)-conducting pore of Kv1.6, hetlaxin is a low-affinity ligand, whereas margatoxin and scyllatoxin do not bind to Kv1.6 pore. Binding of toxins to Kv1.6 pore has considerable inverse dependence on the ionic strength. Model structures of KcsA-Kv1.6 and Kv1.6 complexes with agitoxin 2, kaliotoxin 1 and OSK1 were obtained using homology modeling and molecular dynamics simulation. Interaction interfaces, which are formed by 15-19 toxin residues and 10 channel residues, are described and compared. Specific sites of Kv1.6 pore recognition are identified for targeting of peptide blockers. Analysis of interactions between agitoxin 2 derivatives with point mutations (S7K, S11G, L19S, R31G) and KcsA-Kv1.6 confirms reliability of the calculated complex structure.

  6. Multi-Channel Retailing

    Directory of Open Access Journals (Sweden)

    Dirk Morschett, Dr.,

    2005-01-01

    Full Text Available Multi-channel retailing entails the parallel use by retailing enterprises of several sales channels. The results of an online buyer survey which has been conducted to investigate the impact of multi-channel retailing (i.e. the use of several retail channels by one retail company on consumer behaviour show that the frequently expressed concern that the application of multi-channel systems in retailing would be associated with cannibalization effects, has proven unfounded. Indeed, the appropriate degree of similarity, consistency, integration and agreement achieves the exact opposite. Different channels create different advantages for consumers. Therefore the total benefit an enterprise which has a multi-channel system can offer to its consumers is larger, the greater the number of available channels. The use of multi-channel systems is associated with additional purchases in the different channels. Such systems are thus superior to those offering only one sales channel to their customers. Furthermore, multi-channel systems with integrated channels are superior to those in which the channels are essentially autonomous and independent of one another. In integrated systems, consumers can achieve synergy effects in the use of sales-channel systems. Accordingly, when appropriately formulated, multi-channel systems in retailing impact positively on consumers. They use the channels more frequently, buy more from them and there is a positive customer-loyalty impact. Multi-channel systems are strategic options for achieving customer loyalty, exploiting customer potential and for winning new customers. They are thus well suited for approaching differing and varied target groups.

  7. Surgery for residual convergence excess esotropia.

    Science.gov (United States)

    Patel, Himanshu I; Dawson, Emma; Lee, John

    2011-12-01

    The outcome of bilateral medial rectus posterior fixation sutures +/- central tenotomy was assessed as a secondary procedure for residual convergence excess esotropia in 11 patients. Ten had previously undergone bilateral medial rectus recessions. One had recess/resect surgery on the deviating eye. The average preoperative near angle was 30 prism diopters with a range of 16 to 45 prism diopters. Eight patients underwent bilateral medial rectus posterior fixation sutures with central tenotomy. Two had bilateral medial rectus posterior fixation sutures only, and one had bilateral medial rectus posterior fixation suture, a lateral rectus resection, and an inferior oblique disinsertion. The postoperative near angle ranged from 4-30 prism diopters, with mean of 12 prism diopters. Five patients demonstrated some stereopsis preoperatively, all needing bifocals. Postoperatively, nine patients demonstrated an improvement in stereopsis, none needing bifocals. Two showed smaller near angles and better control without bifocals. Final stereopsis ranged from 30 seconds of arc to 800 seconds of arc. We feel that bilateral medial rectus posterior fixation sutures with or without central tenotomy is a viable secondary procedure for residual convergence excess esotropia.

  8. Neuronal Sodium Channels in Neurodegeneration and Neuroprotection

    Science.gov (United States)

    2002-06-01

    NIL) of the Univ Michigan. Ann Arbor Mr, USA. rat pituitary gland exhibit a 40-50% decrease in sodium current density from postnatal day 3 (P3) to...that deleted all residues beyond the tyr (gIL182STOP). Ankyrin rec of channel production may underlie the suppression of sodium current density. To...subunits con- 11 critical is for ankyrin association. Homophilic cell adhesion through 81 subunits m tributes to the suppression of melanotrope sodium

  9. Modeling the ion channel structure of cecropin.

    OpenAIRE

    Durell, S R; Raghunathan, G.; Guy, H R

    1992-01-01

    Atomic-scale computer models were developed for how cecropin peptides may assemble in membranes to form two types of ion channels. The models are based on experimental data and physiochemical principles. Initially, cecropin peptides, in a helix-bend-helix motif, were arranged as antiparallel dimers to position conserved residues of adjacent monomers in contact. The dimers were postulated to bind to the membrane with the NH2-terminal helices sunken into the head-group layer and the COOH-termin...

  10. Targeting TRP channels for novel migraine therapeutics.

    Science.gov (United States)

    Dussor, Gregory; Yan, J; Xie, Jennifer Y; Ossipov, Michael H; Dodick, David W; Porreca, Frank

    2014-11-19

    Migraine is increasingly understood to be a disorder of the brain. In susceptible individuals, a variety of "triggers" may influence altered central excitability, resulting in the activation and sensitization of trigeminal nociceptive afferents surrounding blood vessels (i.e., the trigeminovascular system), leading to migraine pain. Transient receptor potential (TRP) channels are expressed in a subset of dural afferents, including those containing calcitonin gene related peptide (CGRP). Activation of TRP channels promotes excitation of nociceptive afferent fibers and potentially lead to pain. In addition to pain, allodynia to mechanical and cold stimuli can result from sensitization of both peripheral afferents and of central pain pathways. TRP channels respond to a variety of endogenous conditions including chemical mediators and low pH. These channels can be activated by exogenous stimuli including a wide range of chemical and environmental irritants, some of which have been demonstrated to trigger migraine in humans. Activation of TRP channels can elicit CGRP release, and blocking the effects of CGRP through receptor antagonism or antibody strategies has been demonstrated to be effective in the treatment of migraine. Identification of approaches that can prevent activation of TRP channels provides an additional novel strategy for discovery of migraine therapeutics.

  11. 中南丘陵区两类农林复合生态系统对农药残留物的净化作用%Purification of two kinds of agro-forestry ecosystem to pesticide residues in central southern hill area

    Institute of Scientific and Technical Information of China (English)

    罗天啸; 闫文德; 高超; 陈建国

    2015-01-01

    Effects and mechanisms of agro-forestry ecosystem to eliminate pesticides contaminants had been conducted by taking the hilly agro-forestry ecosystem in Taolin Farm, Miluo County, Hunan Province, South central of China as the example. The results show that for the seven kinds of commonly-used pesticides, the pesticide residues of hilly agro-forestry systems averagely reduced by 29.8%compared with that of the paddy rice system in plains, of seven pesticides, the pesticides of higher decreasing range are chlorothalonil, triadimefon with decreasing range by 42.4%, 35.8%, the pesticide of lower declining range, glyphosate also reduced to 13.8%; The elimination role of agro-forestry system’s paddy soil to pesticide pollutants was achieved by the following ways: firstly, the low aromatic organic matter content in paddy soil of agro-forestry systems was higher, which made the soil microbial life activities at a high level, thus leading organic pesticides entered paddy soils to be easily degraded, and reducing pesticide residues in the soil, secondly, the agro-forestry systems surrounded by forest shield, thus blocking airflow from entering through agricultural pest complex system, thereby reducing the amount of pesticide application, and reducing the risk of contamination of pesticide residues.%以我国中南地区湖南省汩罗市桃林林场典型丘陵农林复合生态系统为例,研究了农林复合生态系统对农药污染物的消除效应及机制。研究表明,对于七种常用的农药,丘陵农林复合系统稻田土壤农药残留量比对照平原稻田系统平均降低29.8%,其中降幅较高者如百菌清、三唑酮分别降低42.4%、35.8%,降幅较低者如草甘膦也降达13.8%。农林复合系统稻田土壤农药污染物的消除通过以下方式来促成的。第一,农林复合系统中稻田土壤芳香度较低的有机质含量较高,这使土壤微生物生命活动处于较高水平,从而进入稻田土壤的

  12. Central core disease

    Directory of Open Access Journals (Sweden)

    Jungbluth Heinz

    2007-05-01

    Full Text Available Abstract Central core disease (CCD is an inherited neuromuscular disorder characterised by central cores on muscle biopsy and clinical features of a congenital myopathy. Prevalence is unknown but the condition is probably more common than other congenital myopathies. CCD typically presents in infancy with hypotonia and motor developmental delay and is characterized by predominantly proximal weakness pronounced in the hip girdle; orthopaedic complications are common and malignant hyperthermia susceptibility (MHS is a frequent complication. CCD and MHS are allelic conditions both due to (predominantly dominant mutations in the skeletal muscle ryanodine receptor (RYR1 gene, encoding the principal skeletal muscle sarcoplasmic reticulum calcium release channel (RyR1. Altered excitability and/or changes in calcium homeostasis within muscle cells due to mutation-induced conformational changes of the RyR protein are considered the main pathogenetic mechanism(s. The diagnosis of CCD is based on the presence of suggestive clinical features and central cores on muscle biopsy; muscle MRI may show a characteristic pattern of selective muscle involvement and aid the diagnosis in cases with equivocal histopathological findings. Mutational analysis of the RYR1 gene may provide genetic confirmation of the diagnosis. Management is mainly supportive and has to anticipate susceptibility to potentially life-threatening reactions to general anaesthesia. Further evaluation of the underlying molecular mechanisms may provide the basis for future rational pharmacological treatment. In the majority of patients, weakness is static or only slowly progressive, with a favourable long-term outcome.

  13. Central line infections - hospitals

    Science.gov (United States)

    ... infection; Central venous catheter - infection; CVC - infection; Central venous device - infection; Infection control - central line infection; Nosocomial infection - central line infection; Hospital acquired ...

  14. Dynamical network of residue-residue contacts reveals coupled allosteric effects in recognition, catalysis, and mutation.

    Science.gov (United States)

    Doshi, Urmi; Holliday, Michael J; Eisenmesser, Elan Z; Hamelberg, Donald

    2016-04-26

    Detailed understanding of how conformational dynamics orchestrates function in allosteric regulation of recognition and catalysis remains ambiguous. Here, we simulate CypA using multiple-microsecond-long atomistic molecular dynamics in explicit solvent and carry out NMR experiments. We analyze a large amount of time-dependent multidimensional data with a coarse-grained approach and map key dynamical features within individual macrostates by defining dynamics in terms of residue-residue contacts. The effects of substrate binding are observed to be largely sensed at a location over 15 Å from the active site, implying its importance in allostery. Using NMR experiments, we confirm that a dynamic cluster of residues in this distal region is directly coupled to the active site. Furthermore, the dynamical network of interresidue contacts is found to be coupled and temporally dispersed, ranging over 4 to 5 orders of magnitude. Finally, using network centrality measures we demonstrate the changes in the communication network, connectivity, and influence of CypA residues upon substrate binding, mutation, and during catalysis. We identify key residues that potentially act as a bottleneck in the communication flow through the distinct regions in CypA and, therefore, as targets for future mutational studies. Mapping these dynamical features and the coupling of dynamics to function has crucial ramifications in understanding allosteric regulation in enzymes and proteins, in general.

  15. Quadratic residues and non-residues selected topics

    CERN Document Server

    Wright, Steve

    2016-01-01

    This book offers an account of the classical theory of quadratic residues and non-residues with the goal of using that theory as a lens through which to view the development of some of the fundamental methods employed in modern elementary, algebraic, and analytic number theory. The first three chapters present some basic facts and the history of quadratic residues and non-residues and discuss various proofs of the Law of Quadratic Reciprosity in depth, with an emphasis on the six proofs that Gauss published. The remaining seven chapters explore some interesting applications of the Law of Quadratic Reciprocity, prove some results concerning the distribution and arithmetic structure of quadratic residues and non-residues, provide a detailed proof of Dirichlet’s Class-Number Formula, and discuss the question of whether quadratic residues are randomly distributed. The text is a valuable resource for graduate and advanced undergraduate students as well as for mathematicians interested in number theory.

  16. Study on properties of residue-residue contacts in protein

    Institute of Scientific and Technical Information of China (English)

    王向红; 柯见洪; 郑亦庄; 陈爱; 徐银香

    2004-01-01

    Residue-residue contacts are very important in forming protein structure. In this work, we calculated theaverage probability of residue-residue contacts in 470 globular proteins and analyzed the distribution of contacts in thedifferent interval of residues using Contacts of Structural Units (CSU) and Structural Classification (SCOP) software. Itwas found that the relationship between the average probability -PL and the residue distance L for four structural classes ofproteins could be expressed as lgPL=a+b×L, where a and b are coefficients. We also discussed the connection between twoaspects of proteins which have equal array residue number and found that the distribution probability was stable (or un-stable) if the proteins had the same (or different) compact (for example synthase) in the same structural class.

  17. Study on properties of residue-residue contacts in protein

    Institute of Scientific and Technical Information of China (English)

    王向红; 柯见洪; 郑亦庄; 陈爱; 徐银香

    2004-01-01

    Residue-residue contacts are very important in forming protein structure. In this work, we calculated the average probability of residue-residue contacts in 470 globular proteins and analyzed the distribution of contacts in the different interval of residues using Contacts of Structural Units (CSU) and Structural Classification (SCOP) software. It was found that the relationship between the average probability PL and the residue distance L for four structural classes of proteins could be expressed as lgPL=a+b×L, where a and b are coefficients. We also discussed the connection between two aspects of proteins which have equal array residue number and found that the distribution probability was stable (or un-stable) if the proteins had the same (or different) comnact (for examnle svnthase) in the same structural class.

  18. USACE Navigation Channels 2012

    Data.gov (United States)

    California Department of Resources — This dataset represents both San Francisco and Los Angeles District navigation channel lines. All San Francisco District channel lines were digitized from CAD files...

  19. Sharing Residual Liability

    DEFF Research Database (Denmark)

    Carbonara, Emanuela; Guerra, Alice; Parisi, Francesco

    2016-01-01

    Economic models of tort law evaluate the efficiency of liability rules in terms of care and activity levels. A liability regime is optimal when it creates incentives to maximize the value of risky activities net of accident and precaution costs. The allocation of primary and residual liability...... the virtues and limits of loss-sharing rules in generating optimal (second-best) incentives and allocations of risk. We find that loss sharing may be optimal in the presence of countervailing policy objectives, homogeneous risk avoiders, and subadditive risk, which potentially offers a valuable tool...

  20. Residual Representations of Spacetime

    CERN Document Server

    Saller, H

    2001-01-01

    Spacetime is modelled by binary relations - by the classes of the automorphisms $\\GL(\\C^2)$ of a complex 2-dimensional vector space with respect to the definite unitary subgroup $\\U(2)$. In extension of Feynman propagators for particle quantum fields representing only the tangent spacetime structure, global spacetime representations are given, formulated as residues using energy-momentum distributions with the invariants as singularities. The associatated quantum fields are characterized by two invariant masses - for time and position - supplementing the one mass for the definite unitary particle sector with another mass for the indefinite unitary interaction sector without asymptotic particle interpretation.

  1. Conductance properties of the inwardly rectifying channel, Kir3.2: molecular and Brownian dynamics study.

    Science.gov (United States)

    Hilder, Tamsyn A; Chung, Shin-Ho

    2013-02-01

    Using the recently unveiled crystal structure, and molecular and Brownian dynamics simulations, we elucidate several conductance properties of the inwardly rectifying potassium channel, Kir3.2, which is implicated in cardiac and neurological disorders. We show that the pore is closed by a hydrophobic gating mechanism similar to that observed in Kv1.2. Once open, potassium ions move into, but not out of, the cell. The asymmetrical current-voltage relationship arises from the lack of negatively charged residues at the narrow intracellular mouth of the channel. When four phenylalanine residues guarding the intracellular gate are mutated to glutamate residues, the channel no longer shows inward rectification. Inward rectification is restored in the mutant Kir3.2 when it becomes blocked by intracellular Mg(2+). Tertiapin, a polypeptide toxin isolated from the honey bee, is known to block several subtypes of the inwardly rectifying channels with differing affinities. We identify critical residues in the toxin and Kir3.2 for the formation of the stable complex. A lysine residue of tertiapin protrudes into the selectivity filter of Kir3.2, while two other basic residues of the toxin form hydrogen bonds with acidic residues located just outside the channel entrance. The depth of the potential of mean force encountered by tertiapin is -16.1kT, thus indicating that the channel will be half-blocked by 0.4μM of the toxin.

  2. Central Solenoid

    CERN Multimedia

    2002-01-01

    The Central Solenoid (CS) is a single layer coil wound internally in a supporting cylinder housed in the cryostat of the Liquid Argon Calorimeter. It was successfully tested at Toshiba in December 2000 and was delivered to CERN in September 2001 ready for integration in the LAr Calorimeter in 2003. An intermediate test of the chimney and proximity cryogenics was successfully performed in June 2002.

  3. Dysfunctional HCN ion channels in neurological diseases.

    Science.gov (United States)

    DiFrancesco, Jacopo C; DiFrancesco, Dario

    2015-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed If (funny current) in heart and Ih in neurons. HCN channels contribute in several ways to neuronal activity and are responsible for many important cellular functions, including cellular excitability, generation, and modulation of rhythmic activity, dendritic integration, transmission of synaptic potentials, and plasticity phenomena. Because of their role, defective HCN channels are natural candidates in the search for potential causes of neurological disorders in humans. Several data, including growing evidence that some forms of epilepsy are associated with HCN mutations, support the notion of an involvement of dysfunctional HCN channels in different experimental models of the disease. Additionally, some anti-epileptic drugs are known to modify the activity of the Ih current. HCN channels are widely expressed in the peripheral nervous system and recent evidence has highlighted the importance of the HCN2 isoform in the transmission of pain. HCN channels are also present in the midbrain system, where they finely regulate the activity of dopaminergic neurons, and a potential role of these channels in the pathogenesis of Parkinson's disease has recently emerged. The function of HCN channels is regulated by specific accessory proteins, which control the correct expression and modulation of the neuronal Ih current. Alteration of these proteins can severely interfere with the physiological channel function, potentially predisposing to pathological conditions. In this review we address the present knowledge of the association between HCN dysfunctions and neurological diseases, including clinical, genetic, and physiopathological

  4. Dysfunctional HCN ion channels in neurological diseases

    Directory of Open Access Journals (Sweden)

    Jacopo C. DiFrancesco

    2015-03-01

    Full Text Available Hyperpolarization-activated cyclic nucleotide-gated (HCN channels are expressed as four different isoforms (HCN1-4 in the heart and in the central and peripheral nervous systems. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed If (funny current in heart and Ih in neurons. HCN channels contribute in several ways to neuronal activity and are responsible for many important cellular functions, including cellular excitability, generation and modulation of rhythmic activity, dendritic integration, transmission of synaptic potentials and plasticity phenomena. Because of their role, defective HCN channels are natural candidates in the search for potential causes of neurological disorders in humans. Several data, including growing evidence that some forms of epilepsy are associated with HCN mutations, support the notion of an involvement of dysfunctional HCN channels in different experimental models of the disease. Additionally, some anti-epileptic drugs are known to modify the activity of the Ih current. HCN channels are widely expressed in the peripheral nervous system and recent evidence has highlighted the importance of the HCN2 isoform in the transmission of pain. HCN channels are also present in the midbrain system, where they finely regulate the activity of dopaminergic neurons, and a potential role of these channels in the pathogenesis of Parkinson’s disease has recently emerged. The function of HCN channels is regulated by specific accessory proteins, which control the correct expression and modulation of the neuronal Ih current. Alteration of these proteins can severely interfere with the physiological channel function, potentially predisposing to pathological conditions. In this review we address the present knowledge of the association between HCN dysfunctions and neurological diseases, including clinical, genetic and

  5. KV7 potassium channels

    DEFF Research Database (Denmark)

    Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A

    2014-01-01

    Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

  6. Quantum Multiple Access Channel

    Institute of Scientific and Technical Information of China (English)

    侯广; 黄民信; 张永德

    2002-01-01

    We consider the transmission of classical information over a quantum channel by many senders, which is a generalization of the two-sender case. The channel capacity region is shown to be a convex hull bound by the yon Neumann entropy and the conditional yon Neumann entropies. The result allows a reasonable distribution of channel capacity over the senders.

  7. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter

    2014-01-01

    About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...

  8. Europa central

    Directory of Open Access Journals (Sweden)

    Karel BARTOSEK

    2010-02-01

    Full Text Available La investigación francesa continúa interesándose por Europa Central. Desde luego, hay límites a este interés en el ambiente general de mi nueva patria: en la ignorancia, producto del largo desinterés de Francia por este espacio después de la Segunda Guerra Mundial, y en el comportamiento y la reflexión de la clase política y de los medios de comunicación (una anécdota para ilustrar este ambiente: durante la preparación de nuestro coloquio «Refugiados e inmigrantes de Europa Central en el movimiento antifascista y la Resistencia en Francia, 1933-1945», celebrado en París en octubre de 1986, el problema de la definición fue planteado concreta y «prácticamente». ¡Y hubo entonces un historiador eminente, para quién Alemania no formaría parte de Europa Central!.

  9. Block of GABA(A) receptor ion channel by penicillin: electrophysiological and modeling insights toward the mechanism.

    Science.gov (United States)

    Rossokhin, Alexey V; Sharonova, Irina N; Bukanova, Julia V; Kolbaev, Sergey N; Skrebitsky, Vladimir G

    2014-11-01

    GABA(A) receptors (GABA(A)R) mainly mediate fast inhibitory neurotransmission in the central nervous system. Different classes of modulators target GABA(A)R properties. Penicillin G (PNG) belongs to the class of noncompetitive antagonists blocking the open GABA(A)R and is a prototype of β-lactam antibiotics. In this study, we combined electrophysiological and modeling approaches to investigate the peculiarities of PNG blockade of GABA-activated currents recorded from isolated rat Purkinje cells and to predict the PNG binding site. Whole-cell patch-сlamp recording and fast application system was used in the electrophysiological experiments. PNG block developed after channel activation and increased with membrane depolarization suggesting that the ligand binds within the open channel pore. PNG blocked stationary component of GABA-activated currents in a concentration-dependent manner with IC50 value of 1.12mM at -70mV. The termination of GABA and PNG co-application was followed by a transient tail current. Protection of the tail current from bicuculline block and dependence of its kinetic parameters on agonist affinity suggest that PNG acts as a sequential open channel blocker that prevents agonist dissociation while the channel remains blocked. We built the GABA(A)R models based on nAChR and GLIC structures and performed an unbiased systematic search of the PNG binding site. Monte-Carlo energy minimization was used to find the lowest energy binding modes. We have shown that PNG binds close to the intracellular vestibule. In both models the maximum contribution to the energy of ligand-receptor interactions revealed residues located on the level of 2', 6' and 9' rings formed by a bundle of M2 transmembrane segments, indicating that these residues most likely participate in PNG binding. The predicted structural models support the described mechanism of PNG block.

  10. Bioenergy from sisal residues

    Energy Technology Data Exchange (ETDEWEB)

    Jungersen, G. [Dansk Teknologisk Inst. (Denmark); Kivaisi, A.; Rubindamayugi, M. [Univ. of Dar es Salaam (Tanzania, United Republic of)

    1998-05-01

    The main objectives of this report are: To analyse the bioenergy potential of the Tanzanian agro-industries, with special emphasis on the Sisal industry, the largest producer of agro-industrial residues in Tanzania; and to upgrade the human capacity and research potential of the Applied Microbiology Unit at the University of Dar es Salaam, in order to ensure a scientific and technological support for future operation and implementation of biogas facilities and anaerobic water treatment systems. The experimental work on sisal residues contains the following issues: Optimal reactor set-up and performance; Pre-treatment methods for treatment of fibre fraction in order to increase the methane yield; Evaluation of the requirement for nutrient addition; Evaluation of the potential for bioethanol production from sisal bulbs. The processing of sisal leaves into dry fibres (decortication) has traditionally been done by the wet processing method, which consumes considerable quantities of water and produces large quantities of waste water. The Tanzania Sisal Authority (TSA) is now developing a dry decortication method, which consumes less water and produces a waste product with 12-15% TS, which is feasible for treatment in CSTR systems (Continously Stirred Tank Reactors). (EG)

  11. Voltage-Gated Calcium Channels in Nociception

    Science.gov (United States)

    Yasuda, Takahiro; Adams, David J.

    Voltage-gated calcium channels (VGCCs) are a large and functionally diverse group of membrane ion channels ubiquitously expressed throughout the central and peripheral nervous systems. VGCCs contribute to various physiological processes and transduce electrical activity into other cellular functions. This chapter provides an overview of biophysical properties of VGCCs, including regulation by auxiliary subunits, and their physiological role in neuronal functions. Subsequently, then we focus on N-type calcium (Cav2.2) channels, in particular their diversity and specific antagonists. We also discuss the role of N-type calcium channels in nociception and pain transmission through primary sensory dorsal root ganglion neurons (nociceptors). It has been shown that these channels are expressed predominantly in nerve terminals of the nociceptors and that they control neurotransmitter release. To date, important roles of N-type calcium channels in pain sensation have been elucidated genetically and pharmacologically, indicating that specific N-type calcium channel antagonists or modulators are particularly useful as therapeutic drugs targeting chronic and neuropathic pain.

  12. Intra-membrane molecular interactions of K+ channel proteins :

    Energy Technology Data Exchange (ETDEWEB)

    Moczydlowski, Edward G.

    2013-07-01

    Ion channel proteins regulate complex patterns of cellular electrical activity and ionic signaling. Certain K+ channels play an important role in immunological biodefense mechanisms of adaptive and innate immunity. Most ion channel proteins are oligomeric complexes with the conductive pore located at the central subunit interface. The long-term activity of many K+ channel proteins is dependent on the concentration of extracellular K+; however, the mechanism is unclear. Thus, this project focused on mechanisms underlying structural stability of tetrameric K+ channels. Using KcsA of Streptomyces lividans as a model K+ channel of known structure, the molecular basis of tetramer stability was investigated by: 1. Bioinformatic analysis of the tetramer interface. 2. Effect of two local anesthetics (lidocaine, tetracaine) on tetramer stability. 3. Molecular simulation of drug docking to the ion conduction pore. The results provide new insights regarding the structural stability of K+ channels and its possible role in cell physiology.

  13. Insight toward epithelial Na+ channel mechanism revealed by the acid-sensing ion channel 1 structure.

    Science.gov (United States)

    Stockand, James D; Staruschenko, Alexander; Pochynyuk, Oleh; Booth, Rachell E; Silverthorn, Dee U

    2008-09-01

    The epithelial Na(+) channel/degenerin (ENaC/DEG) protein family includes a diverse group of ion channels, including nonvoltage-gated Na(+) channels of epithelia and neurons, and the acid-sensing ion channel 1 (ASIC1). In mammalian epithelia, ENaC helps regulate Na(+) and associated water transport, making it a critical determinant of systemic blood pressure and pulmonary mucosal fluidity. In the nervous system, ENaC/DEG proteins are related to sensory transduction. While the importance and physiological function of these ion channels are established, less is known about their structure. One hallmark of the ENaC/DEG channel family is that each channel subunit has only two transmembrane domains connected by an exceedingly large extracellular loop. This subunit structure was recently confirmed when Jasti and colleagues determined the crystal structure of chicken ASIC1, a neuronal acid-sensing ENaC/DEG channel. By mapping ENaC to the structural coordinates of cASIC1, as we do here, we hope to provide insight toward ENaC structure. ENaC, like ASIC1, appears to be a trimeric channel containing 1alpha, 1beta, and 1gamma subunit. Heterotrimeric ENaC and monomeric ENaC subunits within the trimer possibly contain many of the major secondary, tertiary, and quaternary features identified in cASIC1 with a few subtle but critical differences. These differences are expected to have profound effects on channel behavior. In particular, they may contribute to ENaC insensitivity to acid and to its constitutive activity in the absence of time- and ligand-dependent inactivation. Experiments resulting from this comparison of cASIC1 and ENaC may help clarify unresolved issues related to ENaC architecture, and may help identify secondary structures and residues critical to ENaC function.

  14. Protocol channels as a new design alternative of covert channels

    CERN Document Server

    Wendzel, Steffen

    2008-01-01

    Covert channel techniques are used by attackers to transfer hidden data. There are two main categories of covert channels: timing channels and storage channels. This paper introduces a third category called protocol channels. A protocol channel switches one of at least two protocols to send a bit combination to a destination while sent packets include no hidden information themselves.

  15. Surface vacancy channels through ion channeling

    Energy Technology Data Exchange (ETDEWEB)

    Redinger, Alex; Standop, Sebastian; Michely, Thomas [II. Physikalisches Institut, Universitaet Koeln, Zuelpicher Strasse 77, 50937 Koeln (Germany); Rosandi, Yudi; Urbassek, Herbert M. [Fachbereich Physik, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)

    2009-07-01

    Damage patterns of single ion impacts on Pt(111) have been studied by scanning tunneling microscopy (STM) and molecular dynamics simulations (MD). Low temperature experiments, where surface diffusion is absent, have been performed for argon and xenon ions with energies between 1 keV and 15 keV at an angle of incidence of 86 {sup circle} measured with respect to the surface normal. Ions hitting preexisting illuminated step edges penetrate into the crystal and are guided in open crystallographic directions, one or more layers underneath the surface (subsurface channeling). In the case of argon channeling the resulting surface damage consists of adatom and vacancy pairs aligned in ion beam direction. After xenon channeling thin surface vacancy trenches along the ion trajectories - surface vacancy channels - are observed. They result from very efficient sputtering and adatom production along the ion trajectory. This phenomena is well reproduced in molecular dynamics simulations of single ion impacts at 0 K. The damage patterns of Argon and Xenon impacts can be traced back to the different energy losses of the particles in the channel. Channeling distances exceeding 1000 A for 15 keV xenon impacts are observed.

  16. Central pain.

    Science.gov (United States)

    Singh, Supreet

    2014-12-01

    Questions from patients about pain conditions and analgesic pharmacotherapy and responses from authors are presented to help educate patients and make them more effective self-advocates. The topic addressed in this issue is central pain, a neuropathic pain syndrome caused by a lesion in the brain or spinal cord that sensitizes one's perception of pain. It is a debilitating condition caused by various diseases such as multiple sclerosis, strokes, spinal cord injuries, or brain tumors. Varied symptoms and the use of pharmacological medicines and nonpharmacological therapies will be addressed.

  17. central t

    Directory of Open Access Journals (Sweden)

    Manuel R. Piña Monarrez

    2007-01-01

    Full Text Available Dado que la Regresión Ridge (RR, es una estimación sesgada que parte de la solución de la regresión de Mínimos Cuadrados (MC, es vital establecer las condiciones para las que la distribución central t de Student que se utiliza en la prueba de hipótesis en MC, sea también aplicable a la regresión RR. La prueba de este importante resultado se presenta en este artículo.

  18. Micro-mechanisms of residual oil mobilization by viscoelastic fluids

    Institute of Scientific and Technical Information of China (English)

    Zhang Lijuan; Yue Xiang'an; Guo Fenqiao

    2008-01-01

    Four typical types of residual oil, residual oil trapped in dead ends, oil ganglia in pore throats,oil at pore comers and oil film adhered to pore walls, were studied. According to main pore structure characteristics and the fundamental morphological features of residual oil, four displacement models for residual oil were proposed, in which pore-scale flow behavior of viscoelastic fluid was analyzed by a numerical method and micro-mechanisms for mobilization of residual oil were discussed. Calculated results indicate that the viscoelastic effect enhances micro displacement efficiency and increases swept volume. For residual oil trapped in dead ends, the flow field of viscoelastic fluid is developed in dead ends more deeply, resulting in more contact with oil by the displacing fluid, and consequently increasing swept volume. In addition, intense viscoelastic vortex has great stress, under which residual oil becomes small oil ganglia, and finally be carried into main channels. For residual oil at pore throats, its displacement mechanisms are similar to the oil trapped in dead ends. Vortices are developed in the depths of the throats and oil ganglia become smaller. Besides, viscoelastic fluid causes higher pressure drop on oil ganglia, as a driving force, which can overcome capillary force, consequently, flow direction can be changed and the displacing fluid enter smaller throats. For oil at pore comers, viscoelastic fluid can enhance displacement efficiency as a result of greater velocity and stress near the comers. For residual oil adhered to pore wall,viscoelastic fluid can provide a greater displacing force on the interface between viscoelastic fluid and oil,thus, making it easier to exceed the minimum interfacial tension for mobilizing the oil film.

  19. Introduction: Applying Chemical Biology to Ion Channels.

    Science.gov (United States)

    Pless, Stephan A; Ahern, Christopher A

    2015-01-01

    Ion channels are membrane-spanning proteins that control the flow of ions across biological membranes through an aqueous pathway. The opening or closing of this pore can be controlled by a myriad of physiological inputs (voltage, ligands, temperature, metabolites, pH), which in turn allow for the controlled flux of ions across membranes, resulting in the generation of minute electrical signals. The functional implications of ion channel function on physiological processes are vast. Electrical impulses, in the form of action potentials or diverse chemo-electrical signals, coordinate the syncytium of the heart beat, support a myriad of neuronal communication pathways, insulin secretion, and are central to the immune response, with more roles being discovered virtually everyday. Thus, ion channel function is a biophysical process that is central to biological life at many levels. And with over 500 channel-forming subunits known today in humans, this large class of proteins is also increasingly recognised as important drug targets, as inherited or acquired ion channel dysfunction are known causes of disease.

  20. Hierarchically deflated conjugate residual

    CERN Document Server

    Yamaguchi, Azusa

    2016-01-01

    We present a progress report on a new class of multigrid solver algorithm suitable for the solution of 5d chiral fermions such as Domain Wall fermions and the Continued Fraction overlap. Unlike HDCG \\cite{Boyle:2014rwa}, the algorithm works directly on a nearest neighbour fine operator. The fine operator used is Hermitian indefinite, for example $\\Gamma_5 D_{dwf}$, and convergence is achieved with an indefinite matrix solver such as outer iteration based on conjugate residual. As a result coarse space representations of the operator remain nearest neighbour, giving an 8 point stencil rather than the 81 point stencil used in HDCG. It is hoped this may make it viable to recalculate the matrix elements of the little Dirac operator in an HMC evolution.

  1. residue and shunting pinholes

    Science.gov (United States)

    Gorji, Nima E.

    2014-09-01

    The present work considers two observable phenomena through the experimental fabrication and electrical characterization of the rf-sputtered CdS/CdTe thin film solar cells that extremely reduce the overall conversion efficiency of the device: CdCl2 residue on the surface of the semiconductor and shunting pinholes. The former happens through nonuniform treatment of the As-deposited solar cells before annealing at high temperature and the latter occurs by shunting pinholes when the cell surface is shunted by defects, wire-like pathways or scratches on the metallic back contact caused from the external contacts. Such physical problems may be quite common in the experimental activities and reduce the performance down to 4-5 % which leads to dismantle the device despite its precise fabrication. We present our electrical characterization on the samples that received wet CdCl2 surface treatment (uniform or nonuniform) and are damaged by the pinholes.

  2. Residual Symmetries in the Presence of an EM Background

    CERN Document Server

    Carrion, H L; Toppan, F

    2003-01-01

    The symmetry algebra of a QFT in the presence of an external EM background (named "residual symmetry") is investigated within a Lie-algebraic, model independent scheme. Some results previously encountered in the literature are here extended. In particular we compute the symmetry algebra for a constant EM background in D=3 and D=4 dimensions. In D= 3 dimensions the residual symmetry algebra is isomorphic to $u(1)\\oplus {\\cal P}_c(2)$, with ${\\cal P}_c(2)$ the centrally extended 2-dimensional Poincar\\'e algebra. In D=4 dimension the generic residual symmetry algebra is given by a seven-dimensional solvable Lie algebra which is explicitly computed. Residual symmetry algebras are also computed for specific non-constant EM backgrounds.

  3. Residual symmetries in the presence of an EM background

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Leyva, Moises Porfirio; Salazar, Hector Leny Carrion; Toppan, Francesco [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: mrojas, hleny, toppan@cbpf.br

    2001-07-01

    The symmetry algebra of a QFT in the presence of an external EM background (named 'residual symmetry') is investigated within a Lie-algebraic, model independent scheme. Some results previously encountered in the literature are here extended. In particular we compute the symmetry algebra for a constant EM background in D = 3 and D = 4 dimensions. In D = 3 dimensions the residual symmetry algebra is isomorphic to u(1) + P{sub c} (2) the centrally extended 2-dimensional Poincare algebra. In D=4 dimensions the generic residual symmetry algebra is given by a 7 dimensional solvable Lie algebra which is explicitly computed. Residual symmetry algebras are also computed for specific non-constant EM backgrounds. (author)

  4. Residual symmetries in the presence of an EM background

    Energy Technology Data Exchange (ETDEWEB)

    Carrion, H.L.; Rojas, M.; Toppan, F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: hleny@cbpf.br; mrojas@cbpf.br; toppan@cbpf.br

    2002-08-01

    The symmetry algebra of a QFT in the presence of an external EM background (named 'residual symmetry') is investigated within a Lie-algebraic, model independent scheme. Some results previously encountered in the literature are here extended. In particular we compute the symmetry algebra for a constant EM background in D = 3 and D = 4 dimensions. In D = 3 dimensions the residual symmetry algebra is isomorphic to u(1) +P{sub c}(2), with P{sub c}(2) the centrally extended 2-dimensional Poincare algebra. In D = 4 dimension the generic residual symmetry algebra is given by a seven-dimensional solvable Lie algebra which is explicitly computed. residual symmetry algebras are also computed for specific non-constant EM backgrounds. (author)

  5. Side chain flexibility and coupling between the S4-S5 linker and the TRP domain in thermo-sensitive TRP channels: Insights from protein modeling.

    Science.gov (United States)

    Romero-Romero, Sergio; Gomez Lagunas, Froylan; Balleza, Daniel

    2017-04-01

    The transient receptor potential (TRP) superfamily is subdivided into several subfamilies on the basis of sequence similarity, which is highly heterogeneous but shows a molecular architecture that resembles the one present in members of the Kv channel superfamily. Because of this diversity, they produce a large variety of channels with different gating and permeability properties. Elucidation of these particular features necessarily requires comparative studies based on structural and functional data. The present study aims to compilate, analyze, and determine, in a coherent way, the relationship between intrinsic side-chain flexibility and the allosteric coupling in members of the TRPV, TRPM, and TRPC families. Based on the recently determined structures of TRPV1 and TRPV2, we have generated protein models for single subunits of TRPV5, TRPM8, and TRPC5 channels. With these models, we focused our attention on the apparently crucial role of the GP dipeptide at the center of the S4-S5 linker and discussed its role in the interaction with the TRP domain, specifically with the highly-conserved Trp during this coupling. Our analysis suggests an important role of the S4-S5L flexibility in the thermosensitivity, where heat-activated channels possess rigid S4-S5 linkers, whereas cold-activated channels have flexible ones. Finally, we also present evidence of the key interaction between the conserved Trp residue of the TRP box and of several residues in the S4-S5L, importantly the central Pro. Proteins 2017; 85:630-646. © 2016 Wiley Periodicals, Inc.

  6. Experimental determination of residual stress

    Science.gov (United States)

    Ferguson, Milton W.

    1991-01-01

    Residual stresses in finished parts have often been regarded as factors contributing to premature part failure and geometric distortions. Currently, residual stresses in welded structures and railroad components are being investigated. High residual stresses formed in welded structures due primarily to the differential contractions of the weld material as it cools and solidifies can have a profound effect on the surface performance of the structure. In railroad wheels, repeated use of the brakes causes high residual stresses in the rims which may lead to wheel failure and possible derailment. The goals of the study were: (1) to develop strategies for using x-ray diffraction to measure residual stress; (2) to subject samples of Inconel 718 to various mechanical and heat treatments and to measure the resulting stress using x-ray diffraction; and (3) to measure residual stresses in ferromagnetic alloys using magnetoacoustics.

  7. Enhancement of water permeation across nanochannels by partial charges mimicked from biological channels

    Institute of Scientific and Technical Information of China (English)

    Gong Xiao-Jing; Fang Hai-Ping

    2008-01-01

    In biological water channel aquaporins (AQPs), it is believed that the bipolar orientation of the single-file water molecules inside the channel blocks proton permeation but not water transport. In this paper, the water permeation and particularly the water-selective behaviour across a single-walled carbon nanotube (SWNT) with two partial charges adjacent to the well of the SWNT are studied by molecular dynamics simulations, in which the distance between the two partial charges is varied from 0.14nm to 0.5nm and the charges each have a quantity of 0.5e. The two partial charges are used to mimic the charge distribution of the conserved non-pseudoautosomal (NPA) (asparagine/proline/alanine) regions in AQPs. Compared with across the nanochannel in a system with one+1e charge, the water permeation across the nanochannel is greatly enhanced in a system with two+0.5e charges when charges are close to the nanotube, i. e. the two partial charges permit more rapid water diffusion and maintain better bipolar order along the water file when the distance between the two charges and the well of SWNT is smaller than about 0.05nm. The bipolar orientation of the single-file water molecules is crucial for the exclusion of proton transfer. These findings may serve as guidelines for the future nanodevices by using charges to transport water and have biological implications because membrane water channels share a similar single-file water chain and positive charged region at centre and provide an insight into why two residues are necessitated in the central region of water channel protein.

  8. Finite Element Analysis and Experiment Research on Surface Residual Stress of Ceramics Grinding

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The theoretical model of residual stress of ceramics grinding has been established applying thermal elastoplastic mechanics theory. While grinding at the course of grinding wheel moved along workpiece surface the distributing regulation of residual stress can be simplified into thermal elastioplastic mechanical issue, under the action of the both moving centralized force and heat source. Calculating and evaluating of surface residual stress using current procedure of finite element analysis which has been...

  9. Materials recovery from shredder residues

    Energy Technology Data Exchange (ETDEWEB)

    Daniels, E. J.; Jody, B. J.; Pomykala, J., Jr.

    2000-07-24

    Each year, about five (5) million ton of shredder residues are landfilled in the US. Similar quantities are landfilled in Europe and the Pacific Rim. Landfilling of these residues results in a cost to the existing recycling industry and also represents a loss of material resources that are otherwise recyclable. In this paper, the authors outline the resources recoverable from typical shredder residues and describe technology that they have developed to recover these resources.

  10. Residual entropy and simulated annealing

    OpenAIRE

    Ettelaie, R.; Moore, M. A.

    1985-01-01

    Determining the residual entropy in the simulated annealing approach to optimization is shown to provide useful information on the true ground state energy. The one-dimensional Ising spin glass is studied to exemplify the procedure and in this case the residual entropy is related to the number of one-spin flip stable metastable states. The residual entropy decreases to zero only logarithmically slowly with the inverse cooling rate.

  11. River channel patterns: Braided, meandering, and straight

    Science.gov (United States)

    Leopold, Luna B.; Wolman, M. Gordon

    1957-01-01

    Channel pattern is used to describe the plan view of a reach of river as seen from an airplane, and includes meandering, braiding, or relatively straight channels. Natural channels characteristically exhibit alternating pools or deep reaches and riffles or shallow reaches, regardless of the type of pattern. The length of the pool or distance between riffles in a straight channel equals the straight line distance between successive points of inflection in the wave pattern of a meandering river of the same width. The points of inflection are also shallow points and correspond to riffles in the straight channel. This distance, which is half the wavelength of the meander, varies approximately as a linear function of channel width. In the data we analysed the meander wavelength, or twice the distance between successive riffles, is from 7 to 12 times the channel width. It is concluded that the mechanics which may lead to meandering operate in straight channels. River braiding is characterized by channel division around alluvial islands. The growth of an island begins as the deposition of a central bar which results from sorting and deposition of the coarser fractions of the load which locally cannot be transported. The bar grows downstream and in height by continued deposition on its surface, forcing the water into the flanking channels, which, to carry the flow, deepen and cut laterally into the original banks. Such deepening locally lowers the water surface and the central bar emerges as an island which becomes stabilized by vegetation. Braiding was observed in a small river in a laboratory. Measurements of the adjustments of velocity, depth, width, and slope associated with island development lead to the conclusion that braiding is one of the many patterns which can maintain quasi-equilibrium among discharge, load, and transporting ability. Braiding does not necessarily indicate an excess of total load. Channel cross section and pattern are ultimately controlled by

  12. Quantum broadcast channels

    CERN Document Server

    Yard, J; Devetak, I; Yard, Jon; Hayden, Patrick; Devetak, Igor

    2006-01-01

    We analyze quantum broadcast channels, which are quantum channels with a single sender and many receivers. Focusing on channels with two receivers for simplicity, we generalize a number of results from the network Shannon theory literature which give the rates at which two senders can receive a common message, while a personalized one is sent to one of them. Our first collection of results applies to channels with a classical input and quantum outputs. The second class of theorems we prove concern sending a common classical message over a quantum broadcast channel, while sending quantum information to one of the receivers. The third group of results we obtain concern communication over an isometry, giving the rates at quantum information can be sent to one receiver, while common quantum information is sent to both, in the sense that tripartite GHZ entanglement is established. For each scenario, we provide an additivity proof for an appropriate class of channels, yielding single-letter characterizations of the...

  13. Residual strain mapping of Roman styli from Iulia Concordia, Italy

    Energy Technology Data Exchange (ETDEWEB)

    Salvemini, Filomena, E-mail: floriana.salvemini@fi.isc.cnr.it [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Sesto Fiorentino, FI (Italy); Università degli Studi di Firenze, Dipartimento di Scienze della Terra (Italy); Grazzi, Francesco [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Sesto Fiorentino, FI (Italy); Angelini, Ivana [Università degli Studi di Padova, Dipartimento di Geoscienze (Italy); Davydov, Vadim; Vontobel, Peter [Paul Scherrer Institut, SINQ Spallation Neutron Source, Villigen (Switzerland); Vigoni, Alberto [Dedalo s.n.c., Vicolo dei Conti 6, I-35122 Padua (Italy); Artioli, Gilberto [Università degli Studi di Padova, Dipartimento di Geoscienze (Italy); Zoppi, Marco [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Sesto Fiorentino, FI (Italy)

    2014-05-01

    Iulia Concordia is an important Roman settlement known for the production of iron objects and weapons during the Roman Empire. A huge number of well-preserved styli were found in the past century in the bed of an old channel. In order to shed light about the production processes used by Roman for stylus manufacturing, a neutron diffraction residual strain analysis was performed on the POLDI materials science diffractometer at the Paul Scherrer Institut in Switzerland. Here, we present results from our investigation conducted on 11 samples, allowing to define, in a non-invasive way, the residual strain map related to the ancient Roman working techniques. - Highlights: • We examined 11 Roman styli from the settlement of Iulia Concordia, Italy. • We performed a neutron diffraction residual strain analysis on POLDI at PSI (CH). • We identified the production processes used by Roman for stylus manufacturing. • We clarified the way and direction of working applied for different classes of styli.

  14. Evaluation of residue-residue contact predictions in CASP9

    KAUST Repository

    Monastyrskyy, Bohdan

    2011-01-01

    This work presents the results of the assessment of the intramolecular residue-residue contact predictions submitted to CASP9. The methodology for the assessment does not differ from that used in previous CASPs, with two basic evaluation measures being the precision in recognizing contacts and the difference between the distribution of distances in the subset of predicted contact pairs versus all pairs of residues in the structure. The emphasis is placed on the prediction of long-range contacts (i.e., contacts between residues separated by at least 24 residues along sequence) in target proteins that cannot be easily modeled by homology. Although there is considerable activity in the field, the current analysis reports no discernable progress since CASP8.

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

    Science.gov (United States)

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

    2016-03-16

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

  16. 中枢N-型钙离子通道对应激性高血压大鼠去甲肾上腺素释放的影响%Effects of central N-type calcium channels on noradrenaline release from locus coeruleus projecting to hypothalamus in stress induced hypertension rats

    Institute of Scientific and Technical Information of China (English)

    吴军同; 巩万坤; 夏兆俊; 王峰; 黄宏平; 汪萌芽

    2016-01-01

    目的:研究N-型电压门控性钙离子通道影响高血压大鼠的血压以及蓝斑投射到下丘脑去甲肾上腺素释放动力学的机制。方法:将24只雄性SD大鼠(180~200 g)随机分为对照组和模型组,模型组大鼠用噪声和足底电击刺激大鼠血压升高,在建立慢性应激性高血压大鼠模型的基础上,电刺激蓝斑核,运用碳纤维电极检测技术测定大鼠下丘脑内去甲肾上腺素( NE)的释放量,进一步观察给予电压门控性钙离子通道阻断剂对NE的刺激-分泌量和在体血压的影响。结果:与对照组相比,高血压模型组大鼠血压升高(P<0.05),电刺激蓝斑核,下丘脑检测到的去甲肾上腺素的释放信号幅度增大(P<00.5)。侧脑室给予N-型钙离子通道阻断剂使模型组大鼠的血压下降(P<0.05),去甲肾上腺素的释放信号幅度减少(P<0.05)。结论:中枢部位的电压门控N-型钙离子通道参与应激性高血压大鼠下丘脑去甲肾上腺素的释放和血压的调控。%Objective:To observe the dynamic characteristics of norepinephrine ( NE) release in hypothalamus followed by electrical stimulation in locus coeruleus in the rat model of stress-induced hypertension (SIH) and investigate the role of central N-type calcium channel in the pathogenesis of SIH. Methods:24 Male Sprague-Dawley rats (180-200 g) were randomly divided into control and SIH group.The SIH model rats were induced by both noise and foot-shock stresses.After modeling,NE release in the hypothalamus by electrical stimulation in locus coeruleus was determined and NE signal was re-corded by carbon fiber electrode.Results:Blood pressure and the peak value of NE signal in the hypothalamus following electrical stimulation in locus coer-uleus were elevated and higher in SIH rats than the controls ( P<0 .05 ) .Intracerebroventricular administration of ralfinamide mesylate ( sodium and N-type calcium

  17. Quantum feedback channels

    CERN Document Server

    Bowen, G

    2002-01-01

    In classical information theory the capacity of a noisy communication channel cannot be increased by the use of feedback. In quantum information theory the no-cloning theorem means that noiseless copying and feedback of quantum information cannot be achieved. In this paper, quantum feedback is defined as the unlimited use of a noiseless quantum channel from receiver to sender. Given such quantum feedback, it is shown to provide no increase in the entanglement-assisted capacities of a noisy quantum channel, in direct analogy to the classical case. It is also shown that in various cases of non-assisted capacities, feedback can increase the capacity of many quantum channels.

  18. Ion channels in asthma.

    Science.gov (United States)

    Valverde, Miguel A; Cantero-Recasens, Gerard; Garcia-Elias, Anna; Jung, Carole; Carreras-Sureda, Amado; Vicente, Rubén

    2011-09-23

    Ion channels are specialized transmembrane proteins that permit the passive flow of ions following their electrochemical gradients. In the airways, ion channels participate in the production of epithelium-based hydroelectrolytic secretions and in the control of intracellular Ca(2+) levels that will ultimately activate almost all lung cells, either resident or circulating. Thus, ion channels have been the center of many studies aiming to understand asthma pathophysiological mechanisms or to identify therapeutic targets for better control of the disease. In this minireview, we focus on molecular, genetic, and animal model studies associating ion channels with asthma.

  19. TRP channels in schistosomes

    Directory of Open Access Journals (Sweden)

    Swarna Bais

    2016-12-01

    Full Text Available Praziquantel (PZQ is effectively the only drug currently available for treatment and control of schistosomiasis, a disease affecting hundreds of millions of people worldwide. Many anthelmintics, likely including PZQ, target ion channels, membrane protein complexes essential for normal functioning of the neuromusculature and other tissues. Despite this fact, only a few classes of parasitic helminth ion channels have been assessed for their pharmacological properties or for their roles in parasite physiology. One such overlooked group of ion channels is the transient receptor potential (TRP channel superfamily. TRP channels share a common core structure, but are widely diverse in their activation mechanisms and ion selectivity. They are critical to transducing sensory signals, responding to a wide range of external stimuli. They are also involved in other functions, such as regulating intracellular calcium and organellar ion homeostasis and trafficking. Here, we review current literature on parasitic helminth TRP channels, focusing on those in schistosomes. We discuss the likely roles of these channels in sensory and locomotor activity, including the possible significance of a class of TRP channels (TRPV that is absent in schistosomes. We also focus on evidence indicating that at least one schistosome TRP channel (SmTRPA has atypical, TRPV1-like pharmacological sensitivities that could potentially be exploited for future therapeutic targeting.

  20. Identification of the molecular site of ivabradine binding to HCN4 channels.

    Directory of Open Access Journals (Sweden)

    Annalisa Bucchi

    Full Text Available Ivabradine is a specific heart rate-reducing agent approved as a treatment of chronic stable angina. Its mode of action involves a selective and specific block of HCN channels, the molecular components of sinoatrial "funny" (f-channels. Different studies suggest that the binding site of ivabradine is located in the inner vestibule of HCN channels, but the molecular details of ivabradine binding are unknown. We thus sought to investigate by mutagenesis and in silico analysis which residues of the HCN4 channel, the HCN isoform expressed in the sinoatrial node, are involved in the binding of ivabradine. Using homology modeling, we verified the presence of an inner cavity below the channel pore and identified residues lining the cavity; these residues were replaced with alanine (or valine either alone or in combination, and WT and mutant channels were expressed in HEK293 cells. Comparison of the block efficiency of mutant vs WT channels, measured by patch-clamp, revealed that residues Y506, F509 and I510 are involved in ivabradine binding. For each mutant channel, docking simulations correctly explain the reduced block efficiency in terms of proportionally reduced affinity for ivabradine binding. In summary our study shows that ivabradine occupies a cavity below the channel pore, and identifies specific residues facing this cavity that interact and stabilize the ivabradine molecule. This study provides an interpretation of known properties of f/HCN4 channel block by ivabradine such as the "open channel block", the current-dependence of block and the property of "trapping" of drug molecules in the closed configuration.

  1. Erroneous laboratory values obtained from central catheters.

    Science.gov (United States)

    Johnston, J B; Messina, M

    1991-01-01

    Serious analytic errors in potassium measurements have been identified in blood specimens obtained from newly inserted central catheters. Erroneous elevated readings have been related to interactions of chemistry analyzer electrodes and substances fixed to external and intraluminal walls of the central catheter. Anecdotal summaries of this phenomenon are presented to enable the nurse to recognize potential problems when sampling blood from central catheters. Studies were performed to determine the amount of flush necessary to clear the catheter of interfering residue. To eliminate this potentially hazardous occurrence, recommended flush volumes, nursing implications, and actions are described.

  2. Mode Switching for the Multi-Antenna Broadcast Channel Based on Delay and Channel Quantization

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2009-01-01

    Full Text Available Imperfect channel state information degrades the performance of multiple-input multiple-output (MIMO communications; its effects on single-user (SU and multiuser (MU MIMO transmissions are quite different. In particular, MU-MIMO suffers from residual interuser interference due to imperfect channel state information while SU-MIMO only suffers from a power loss. This paper compares the throughput loss of both SU and MU-MIMO in the broadcast channel due to delay and channel quantization. Accurate closed-form approximations are derived for achievable rates for both SU and MU-MIMO. It is shown that SU-MIMO is relatively robust to delayed and quantized channel information, while MU-MIMO with zero-forcing precoding loses its spatial multiplexing gain with a fixed delay or fixed codebook size. Based on derived achievable rates, a mode switching algorithm is proposed, which switches between SU and MU-MIMO modes to improve the spectral efficiency based on average signal-to-noise ratio (SNR, normalized Doppler frequency, and the channel quantization codebook size. The operating regions for SU and MU modes with different delays and codebook sizes are determined, and they can be used to select the preferred mode. It is shown that the MU mode is active only when the normalized Doppler frequency is very small, and the codebook size is large.

  3. Landfilling of waste incineration residues

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Astrup, Thomas; Cai, Zuansi

    2002-01-01

    Residues from waste incineration are bottom ashes and air-pollution-control (APC) residues including fly ashes. The leaching of heavy metals and salts from the ashes is substantial and a wide spectrum of leaching tests and corresponding criteria have been introduced to regulate the landfilling...

  4. Residual number processing in dyscalculia.

    OpenAIRE

    Cappelletti, M.; Price, C.J.

    2014-01-01

    Developmental dyscalculia - a congenital learning disability in understanding numerical concepts - is typically associated with parietal lobe abnormality. However, people with dyscalculia often retain some residual numerical abilities, reported in studies that otherwise focused on abnormalities in the dyscalculic brain. Here we took a different perspective by focusing on brain regions that support residual number processing in dyscalculia. All participants accurately performed semantic and ca...

  5. A linearization of quantum channels

    Science.gov (United States)

    Crowder, Tanner

    2015-06-01

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

  6. Ion channels in toxicology.

    Science.gov (United States)

    Restrepo-Angulo, Iván; De Vizcaya-Ruiz, Andrea; Camacho, Javier

    2010-08-01

    Ion channels play essential roles in human physiology and toxicology. Cardiac contraction, neural transmission, temperature sensing, insulin release, regulation of apoptosis, cellular pH and oxidative stress, as well as detection of active compounds from chilli, are some of the processes in which ion channels have an important role. Regulation of ion channels by several chemicals including those found in air, water and soil represents an interesting potential link between environmental pollution and human diseases; for instance, de novo expression of ion channels in response to exposure to carcinogens is being considered as a potential tool for cancer diagnosis and therapy. Non-specific binding of several drugs to ion channels is responsible for a huge number of undesirable side-effects, and testing guidelines for several drugs now require ion channel screening for pharmaceutical safety. Animal toxins targeting human ion channels have serious effects on the population and have also provided a remarkable tool to study the molecular structure and function of ion channels. In this review, we will summarize the participation of ion channels in biological processes extensively used in toxicological studies, including cardiac function, apoptosis and cell proliferation. Major findings on the adverse effects of drugs on ion channels as well as the regulation of these proteins by different chemicals, including some pesticides, are also reviewed. Association of ion channels and toxicology in several biological processes strongly suggests these proteins to be excellent candidates to follow the toxic effects of xenobiotics, and as potential early indicators of life-threatening situations including chronic degenerative diseases.

  7. Statistical inference on residual life

    CERN Document Server

    Jeong, Jong-Hyeon

    2014-01-01

    This is a monograph on the concept of residual life, which is an alternative summary measure of time-to-event data, or survival data. The mean residual life has been used for many years under the name of life expectancy, so it is a natural concept for summarizing survival or reliability data. It is also more interpretable than the popular hazard function, especially for communications between patients and physicians regarding the efficacy of a new drug in the medical field. This book reviews existing statistical methods to infer the residual life distribution. The review and comparison includes existing inference methods for mean and median, or quantile, residual life analysis through medical data examples. The concept of the residual life is also extended to competing risks analysis. The targeted audience includes biostatisticians, graduate students, and PhD (bio)statisticians. Knowledge in survival analysis at an introductory graduate level is advisable prior to reading this book.

  8. Quantifying residual stress in nanoscale thin polymer films via surface wrinkling.

    Science.gov (United States)

    Chung, Jun Young; Chastek, Thomas Q; Fasolka, Michael J; Ro, Hyun Wook; Stafford, Christopher M

    2009-04-28

    Residual stress, a pervasive consequence of solid materials processing, is stress that remains in a material after external forces have been removed. In polymeric materials, residual stress results from processes, such as film formation, that force and then trap polymer chains into nonequilibrium stressed conformations. In solvent-cast films, which are central to a wide range of technologies, residual stress can cause detrimental effects, including microscopic defect formation and macroscopic dimensional changes. Since residual stress is difficult to measure accurately, particularly in nanoscale thin polymer films, it remains a challenge to understand and control. We present here a quantitative method of assessing residual stress in polymer thin films by monitoring the onset of strain-induced wrinkling instabilities. Using this approach, we show that thin (>100 nm) polystyrene films prepared via spin-coating possess residual stresses of approximately 30 MPa, close to the crazing and yield stress. In contrast to conventional stress measurement techniques such as wafer curvature, our technique has the resolution to measure residual stress in films as thin as 25 nm. Furthermore, we measure the dissipation of residual stress through two relaxation mechanisms: thermal annealing and plasticizer addition. In quantifying the amount of residual stress in these films, we find that the residual stress gradually decreases with increasing annealing time and plasticizer amounts. Our robust and simple route to measure residual stress adds a key component to the understanding of polymer thin film behavior and will enable identification of more effective processing routes that mitigate the detrimental effects of residual stress.

  9. Mechanosensor Channels in Mammalian Somatosensory Neurons

    Directory of Open Access Journals (Sweden)

    Patrick Delmas

    2007-09-01

    Full Text Available Mechanoreceptive sensory neurons innervating the skin, skeletal muscles andviscera signal both innocuous and noxious information necessary for proprioception, touchand pain. These neurons are responsible for the transduction of mechanical stimuli intoaction potentials that propagate to the central nervous system. The ability of these cells todetect mechanical stimuli impinging on them relies on the presence of mechanosensitivechannels that transduce the external mechanical forces into electrical and chemical signals.Although a great deal of information regarding the molecular and biophysical properties ofmechanosensitive channels in prokaryotes has been accumulated over the past two decades,less is known about the mechanosensitive channels necessary for proprioception and thesenses of touch and pain. This review summarizes the most pertinent data onmechanosensitive channels of mammalian somatosensory neurons, focusing on theirproperties, pharmacology and putative identity.

  10. Potassium channels in pulmonary arterial hypertension.

    Science.gov (United States)

    Boucherat, Olivier; Chabot, Sophie; Antigny, Fabrice; Perros, Frédéric; Provencher, Steeve; Bonnet, Sébastien

    2015-10-01

    Pulmonary arterial hypertension (PAH) is a devastating cardiopulmonary disorder with various origins. All forms of PAH share a common pulmonary arteriopathy characterised by vasoconstriction, remodelling of the pre-capillary pulmonary vessel wall, and in situ thrombosis. Although the pathogenesis of PAH is recognised as a complex and multifactorial process, there is growing evidence that potassium channels dysfunction in pulmonary artery smooth muscle cells is a hallmark of PAH. Besides regulating many physiological functions, reduced potassium channels expression and/or activity have significant effects on PAH establishment and progression. This review describes the molecular mechanisms and physiological consequences of potassium channel modulation. Special emphasis is placed on KCNA5 (Kv1.5) and KCNK3 (TASK1), which are considered to play a central role in determining pulmonary vascular tone and may represent attractive therapeutic targets in the treatment of PAH.

  11. Growing Role of Retail in Distribution Channels

    OpenAIRE

    Ishak Mesic

    2011-01-01

    This article aims to demonstrate the growing role of retail trade (retail) in the channels of distribution of goods both in domestic and international markets. Technical-technological development has provided great opportunities for all production of material goods, so that the focus of problem in the economic possibilities of playing shifted from production to sales opportunities, or consumption. The ultimate consumers and their needs and requirements have become a central area of study, bas...

  12. Athermalized channeled spectropolarimeter enhancement.

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-01

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

  13. Voltage-Gated Channels as Causative Agents for Epilepsies

    Directory of Open Access Journals (Sweden)

    Mutasem Abuhamed

    2008-01-01

    Full Text Available Problem statement: Epilepsy is a common neurological disorder that afflicts 1-2% of the general population worldwide. It encompasses a variety of disorders with seizures. Approach: Idiopathic epilepsies were defined as a heterogeneous group of seizure disorders that show no underlying cause .Voltage-gated ion channels defect were recognized etiology of epilepsy in the central nervous system. The aim of this article was to provide an update on voltage-gated channels and their mutation as causative agents for epilepsies. We described the structures of the voltage-gated channels, discuss their current genetic studies, and then review the effects of voltage-gated channels as causative agents for epilepsies. Results: Channels control the flow of ions in and out of the cell causing depolarization and hyper polarization of the cell. Voltage-gated channels were classified into four types: Sodium, potassium calcium ands chloride. Voltage-gated channels were macromolecular protein complexes within the lipid membrane. They were divided into subunits. Each subunit had a specific function and was encoded by more than one gen. Conclusion: Current genetic studies of idiopathic epilepsies show the importance of genetic influence on Voltage-gated channels. Different genes may regulate a function in a channel; the channel defect was directly responsible for neuronal hyper excitability and seizures.

  14. Observation and modeling of the storm-induced fluid mud dynamics in a muddy-estuarine navigational channel

    Science.gov (United States)

    Wan, Yuanyang; Roelvink, Dano; Li, Weihua; Qi, Dingman; Gu, Fengfeng

    2014-07-01

    Observations of storm-induced fluid mud dynamics have been conducted at the North Passage deepwater navigational channel (DNC) of the Yangtze Estuary in October to December 2010, during the occurrence of a cold-air front. The measurement data reveal that just after the critical wind wave event, a large amount of fine sediment was trapped in a state of fluid mud along the channel. The observed thickness of the fluid mud was up to about 1-5 m, which caused some significant economic and safety problems for shipping traffic in the Yangtze Delta area. The mechanisms and transport processes of the storm-induced fluid mud are analyzed and presented from the angles of both process-oriented and engineering-oriented methods. With the help of hydrodynamics and wave modeling, it could be inferred that the behavior of the storm-induced fluid mud event mainly depends on the overall hydrodynamic regimes and the exchanges of sediment, which is released by storm-wave agitation from adjacent tidal flats. These sediments are accumulated as fluid mud, and subsequently oscillate and persist at those locations with weaker longitudinal residuals in the river- and tide-dominated estuary. In addition, the downslope transport of fluid mud is also thought to have stimulated and worsened the fluid mud event observed in this study. Our modeling results and observations demonstrate that: (1) the transport of fluid mud is an advective phenomenon determining the central position of fluid mud layer along the channel, and it's also a tidal energy influenced phenomenon controlling the erosion and accumulation of fluid mud; and (2) both suspended particulate matter availability and local residual flow regime are of critical importance in determining the trapping probability of sediment and the occurrence of fluid mud.

  15. The S4-S5 linker acts as a signal integrator for HERG K+ channel activation and deactivation gating.

    Science.gov (United States)

    Ng, Chai Ann; Perry, Matthew D; Tan, Peter S; Hill, Adam P; Kuchel, Philip W; Vandenberg, Jamie I

    2012-01-01

    Human ether-à-go-go-related gene (hERG) K(+) channels have unusual gating kinetics. Characterised by slow activation/deactivation but rapid inactivation/recovery from inactivation, the unique gating kinetics underlie the central role hERG channels play in cardiac repolarisation. The slow activation and deactivation kinetics are regulated in part by the S4-S5 linker, which couples movement of the voltage sensor domain to opening of the activation gate at the distal end of the inner helix of the pore domain. It has also been suggested that cytosolic domains may interact with the S4-S5 linker to regulate activation and deactivation kinetics. Here, we show that the solution structure of a peptide corresponding to the S4-S5 linker of hERG contains an amphipathic helix. The effects of mutations at the majority of residues in the S4-S5 linker of hERG were consistent with the previously identified role in coupling voltage sensor movement to the activation gate. However, mutations to Ser543, Tyr545, Gly546 and Ala548 had more complex phenotypes indicating that these residues are involved in additional interactions. We propose a model in which the S4-S5 linker, in addition to coupling VSD movement to the activation gate, also contributes to interactions that stabilise the closed state and a separate set of interactions that stabilise the open state. The S4-S5 linker therefore acts as a signal integrator and plays a crucial role in the slow deactivation kinetics of the channel.

  16. Non-silent story on synonymous sites in voltage-gated ion channel genes.

    Directory of Open Access Journals (Sweden)

    Tong Zhou

    Full Text Available Synonymous mutations are usually referred to as "silent", but increasing evidence shows that they are not neutral in a wide range of organisms. We looked into the relationship between synonymous codon usage bias and residue importance of voltage-gated ion channel proteins in mice, rats, and humans. We tested whether translationally optimal codons are associated with transmembrane or channel-forming regions, i.e., the sites that are particularly likely to be involved in the closing and opening of an ion channel. Our hypothesis is that translationally optimal codons are preferred at the sites within transmembrane domains or channel-forming regions in voltage-gated ion channel genes to avoid mistranslation-induced protein misfolding or loss-of-function. Using the Mantel-Haenszel procedure, which applies to categorical data, we found that translationally optimal codons are more likely to be used at transmembrane residues and the residues involved in channel-forming. We also found that the conservation level at synonymous sites in the transmembrane region is significantly higher than that in the non-transmembrane region. This study provides evidence that synonymous sites in voltage-gated ion channel genes are not neutral. Silent mutations at channel-related sites may lead to dysfunction of the ion channel.

  17. Non-silent story on synonymous sites in voltage-gated ion channel genes.

    Science.gov (United States)

    Zhou, Tong; Ko, Eun A; Gu, Wanjun; Lim, Inja; Bang, Hyoweon; Ko, Jae-Hong

    2012-01-01

    Synonymous mutations are usually referred to as "silent", but increasing evidence shows that they are not neutral in a wide range of organisms. We looked into the relationship between synonymous codon usage bias and residue importance of voltage-gated ion channel proteins in mice, rats, and humans. We tested whether translationally optimal codons are associated with transmembrane or channel-forming regions, i.e., the sites that are particularly likely to be involved in the closing and opening of an ion channel. Our hypothesis is that translationally optimal codons are preferred at the sites within transmembrane domains or channel-forming regions in voltage-gated ion channel genes to avoid mistranslation-induced protein misfolding or loss-of-function. Using the Mantel-Haenszel procedure, which applies to categorical data, we found that translationally optimal codons are more likely to be used at transmembrane residues and the residues involved in channel-forming. We also found that the conservation level at synonymous sites in the transmembrane region is significantly higher than that in the non-transmembrane region. This study provides evidence that synonymous sites in voltage-gated ion channel genes are not neutral. Silent mutations at channel-related sites may lead to dysfunction of the ion channel.

  18. Starnet, a fiber optic metropolitan area network with centralized control

    Science.gov (United States)

    Bacilieri, P.; Caccia, B.; Cardarelli, R.; Carlucci, G. P.; Ciaffoni, O.; Coli, M.; Di Pirro, G.; Ferrer, M. L.; Ghiselli, A.; Martini, A.; Medici, G.; Mirabelli, G.; Pace, E.; Santonico, R.; Trasatti, L.; Valente, E.; Valentini, S.

    1989-12-01

    We present here a project involving a new long distance, high speed, fiber optic network with a passive star topology. The medium access mechanism is based on a centralized controller allowing channel reservation. This controller is connected to each station through an independent pair of optical fibers. It grants access using a deterministic scheme (DAMA/ICCC, demand assignment multiple access by independent centrally controlled channel) by means of a Round Robin algorithm allowing a simple implementation of priority levels and very high data channel efficiency. An overview of the first implementation design is given and some experimental results are presented.

  19. 霍乱毒素对三氟氯氰菊酯抗性及敏感棉铃虫神经细胞L型钙通道的调节作用%Modulations by CTX of the L-type Ca2+ channels in the central neurons of the cyhalothrin-resistant and cyhalothrin-susceptible cotton bollworm, Helicoverpa armigera

    Institute of Scientific and Technical Information of China (English)

    赵强; 李杰; 刘燕强; 范贤林; 季青; 刘安西

    2006-01-01

    霍乱毒素(CTX)可激活兴奋性异三聚体G蛋白(Gαs)的α-亚基和刺激电压门控L-型钙通道,而昆虫的L-型钙通道可能是拟除虫菊酯类杀虫剂的作用靶点.为进一步探讨农业害虫对拟除虫菊酯类杀虫剂产生抗药性的作用机理,我们检测了CTX对三氟氯氰菊酯抗性及敏感棉铃虫Helicoverpa armigera中枢神经细胞电压门控L-型钙通道的调节作用.分别急性分离三氟氯氰菊酯抗性及敏感的3~4龄棉铃虫幼虫胸腹神经节细胞,并在改良的L15培养基(加入或未加入700 ng/mL的CTX)中培养12~16 h.钡离子为载流子,应用全细胞膜片钳技术记录电压门控L-型钙通道电流.结果显示,CTX可使敏感组棉铃虫神经细胞L-型钙通道的峰值电流密度增大36%、峰值电压左移5 mV,但对抗性组棉铃虫神经细胞L-型钙通道无上述作用.并且,CTX对敏感组及抗性组棉铃虫神经细胞L-型钙通道的激活电位、翻转电位、激活曲线和失活曲线等其他一些参数的影响也不明显.在无CTX作用时,所检测到的抗性组与敏感组棉铃虫神经细胞L-型钙通道的上述参数值间差异不显著.结果提示,棉铃虫神经细胞内存在Gs-腺苷酸环化酶(AC)-cAMP-蛋白激酶A (PKA)-L-型钙通道信号调节系统;与敏感棉铃虫神经细胞L-型钙通道相比,三氟氯氰菊酯抗性棉铃虫神经细胞L-型钙通道的活性相对不易受到CTX调节,这可能与昆虫对拟除虫菊酯产生抗药性的机理有关.%Cholera toxin (CTX) activates the α-subunit of stimulatory heterotrimeric G-proteins (Gαs) and stimulates voltage-gated L-type (Ca2+(L)) channels, which may be primary targets of pyrethroids. To investigate the potential mechanisms underlying the resistance to pyrethroids in agriculturally important insect pests, we examined the modulations by CTX of Ca2+(L) channels in the central neurons of the cyhalothrin-resistant (Cy-R) and cyhalothrin-susceptible (Cy-S) cotton

  20. Biomassa, decomposição e cobertura do solo ocasionada por resíduos culturais de três espécies vegetais na região centro-oeste do Brasil Biomass, decomposition and soil cover by residues of three plant species in central- western Brazil

    Directory of Open Access Journals (Sweden)

    Carlo Adriano Boer

    2008-04-01

    Full Text Available Com a crescente adoção da semeadura direta na região Centro-Oeste do Brasil, faz-se necessário maior conhecimento sobre as plantas de cobertura para produção de palha. O presente estudo teve como objetivo avaliar a produção de biomassa verde e seca, a percentagem de cobertura do solo, bem como a dinâmica da decomposição da palhada de três espécies de plantas de cobertura em safrinha: amaranto (Amaranthus cruentus L. BRS Alegria, milheto (Pennisetum glaucum L. var. ADR500 e capim-pé-de-galinha [Eleusine coracana (L. Gaertn.]. O trabalho foi conduzido em um Latossolo Vermelho distroférrico textura argilosa. O delineamento experimental utilizado foi o de blocos casualizados, no esquema de parcelas subdivididas no tempo, com quatro repetições. Nas parcelas foram alocadas as espécies, subdivididas em nove épocas de avaliação (0, 30, 60, 90, 120, 150, 180, 210 e 240 dias após dessecação química das espécies em estudo. Amostras proporcionais da biomassa seca de cada espécie foram acondicionadas em bolsas de decomposição, que foram dispostas sobre o solo, sendo coletadas a cada 30 dias e pesadas até 240 dias após a instalação, para avaliar a dinâmica de decomposição, após o manejo das plantas de cobertura. O milheto ADR500 e o capim-pé-de-galinha proporcionaram maior produção de biomassa verde e seca, maior cobertura do solo e menores taxas de decomposição da palhada, não diferindo entre si. O milheto ADR500 apresentou maior relação C/N, seguido pelo capim-pé-de-galinha e amaranto. Ajustaram-se, para a percentagem de cobertura do solo e a decomposição de palhadas com o tempo, os modelos sigmoidal e exponencial decrescente, respectivamente. O milheto ADR500 e o capim-pé-de-galinha apresentaram comportamentos semelhantes, não diferindo na comparação dos modelos de cobertura do solo e decomposição de palhadas.With the prevalence of no-till systems in Central-Western Brazil, a more in-depth knowledge

  1. Precipitation patterns during channel flow

    Science.gov (United States)

    Jamtveit, B.; Hawkins, C.; Benning, L. G.; Meier, D.; Hammer, O.; Angheluta, L.

    2013-12-01

    Mineral precipitation during channelized fluid flow is widespread in a wide variety of geological systems. It is also a common and costly phenomenon in many industrial processes that involve fluid flow in pipelines. It is often referred to as scale formation and encountered in a large number of industries, including paper production, chemical manufacturing, cement operations, food processing, as well as non-renewable (i.e. oil and gas) and renewable (i.e. geothermal) energy production. We have studied the incipient stages of growth of amorphous silica on steel plates emplaced into the central areas of the ca. 1 meter in diameter sized pipelines used at the hydrothermal power plant at Hellisheidi, Iceland (with a capacity of ca 300 MW electricity and 100 MW hot water). Silica precipitation takes place over a period of ca. 2 months at approximately 120°C and a flow rate around 1 m/s. The growth produces asymmetric ca. 1mm high dendritic structures ';leaning' towards the incoming fluid flow. A novel phase-field model combined with the lattice Boltzmann method is introduced to study how the growth morphologies vary under different hydrodynamic conditions, including non-laminar systems with turbulent mixing. The model accurately predicts the observed morphologies and is directly relevant for understanding the more general problem of precipitation influenced by turbulent mixing during flow in channels with rough walls and even for porous flow. Reference: Hawkins, C., Angheluta, L., Hammer, Ø., and Jamtveit, B., Precipitation dendrites in channel flow. Europhysics Letters, 102, 54001

  2. Kv Channel S1-S2 Linker Working as a Binding Site of Human β-Defensin 2 for Channel Activation Modulation.

    Science.gov (United States)

    Feng, Jing; Yang, Weishan; Xie, Zili; Xiang, Fang; Cao, Zhijian; Li, Wenxin; Hu, Hongzhen; Chen, Zongyun; Wu, Yingliang

    2015-06-19

    Among the three extracellular domains of the tetrameric voltage-gated K(+) (Kv) channels consisting of six membrane-spanning helical segments named S1-S6, the functional role of the S1-S2 linker still remains unclear because of the lack of a peptide ligand. In this study, the Kv1.3 channel S1-S2 linker was reported as a novel receptor site for human β-defensin 2 (hBD2). hBD2 shifts the conductance-voltage relationship curve of the human Kv1.3 channel in a positive direction by nearly 10.5 mV and increases the activation time constant for the channel. Unlike classical gating modifiers of toxin peptides from animal venoms, which generally bind to the Kv channel S3-S4 linker, hBD2 only targets residues in both the N and C termini of the S1-S2 linker to influence channel gating and inhibit channel currents. The increment and decrement of the basic residue number in a positively charged S4 sensor of Kv1.3 channel yields conductance-voltage relationship curves in the positive direction by ∼31.2 mV and 2-4 mV, which suggests that positively charged hBD2 is anchored in the channel S1-S2 linker and is modulating channel activation through electrostatic repulsion with an adjacent S4 helix. Together, these findings reveal a novel peptide ligand that binds with the Kv channel S1-S2 linker to modulate channel activation. These findings also highlight the functional importance of the Kv channel S1-S2 linker in ligand recognition and modification of channel activation.

  3. Channel Access in Erlang

    Energy Technology Data Exchange (ETDEWEB)

    Nicklaus, Dennis J. [Fermilab

    2013-10-13

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

  4. Nitrogen availability of biogas residues

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed Fouda, Sara

    2011-09-07

    The objectives of this study were to characterize biogas residues either unseparated or separated into a liquid and a solid phase from the fermentation of different substrates with respect to their N and C content. In addition, short and long term effects of the application of these biogas residues on the N availability and N utilization by ryegrass was investigated. It is concluded that unseparated or liquid separated biogas residues provide N at least corresponding to their ammonium content and that after the first fertilizer application the C{sub org}:N{sub org} ratio of the biogas residues was a crucial factor for the N availability. After long term application, the organic N accumulated in the soil leads to an increased release of N.

  5. Eag1 K+ Channel: Endogenous Regulation and Functions in Nervous System

    Science.gov (United States)

    Tokay, Tursonjan; Zhang, Guangming; Sun, Peng

    2017-01-01

    Ether-à-go-go1 (Eag1, Kv10.1, KCNH1) K+ channel is a member of the voltage-gated K+ channel family mainly distributed in the central nervous system and cancer cells. Like other types of voltage-gated K+ channels, the EAG1 channels are regulated by a variety of endogenous signals including reactive oxygen species, rendering the EAG1 to be in the redox-regulated ion channel family. The role of EAG1 channels in tumor development and its therapeutic significance have been well established. Meanwhile, the importance of hEAG1 channels in the nervous system is now increasingly appreciated. The present review will focus on the recent progress on the channel regulation by endogenous signals and the potential functions of EAG1 channels in normal neuronal signaling as well as neurological diseases.

  6. Eag1 K+ Channel: Endogenous Regulation and Functions in Nervous System

    Directory of Open Access Journals (Sweden)

    Bo Han

    2017-01-01

    Full Text Available Ether-à-go-go1 (Eag1, Kv10.1, KCNH1 K+ channel is a member of the voltage-gated K+ channel family mainly distributed in the central nervous system and cancer cells. Like other types of voltage-gated K+ channels, the EAG1 channels are regulated by a variety of endogenous signals including reactive oxygen species, rendering the EAG1 to be in the redox-regulated ion channel family. The role of EAG1 channels in tumor development and its therapeutic significance have been well established. Meanwhile, the importance of hEAG1 channels in the nervous system is now increasingly appreciated. The present review will focus on the recent progress on the channel regulation by endogenous signals and the potential functions of EAG1 channels in normal neuronal signaling as well as neurological diseases.

  7. Mutations Causing Slow-Channel Myasthenia Reveal That a Valine Ring in the Channel Pore of Muscle AChR is Optimized for Stabilizing Channel Gating.

    Science.gov (United States)

    Shen, Xin-Ming; Okuno, Tatsuya; Milone, Margherita; Otsuka, Kenji; Takahashi, Koji; Komaki, Hirofumi; Giles, Elizabeth; Ohno, Kinji; Engel, Andrew G

    2016-10-01

    We identify two novel mutations in acetylcholine receptor (AChR) causing a slow-channel congenital myasthenia syndrome (CMS) in three unrelated patients (Pts). Pt 1 harbors a heterozygous βV266A mutation (p.Val289Ala) in the second transmembrane domain (M2) of the AChR β subunit (CHRNB1). Pts 2 and 3 carry the same mutation at an equivalent site in the ε subunit (CHRNE), εV265A (p.Val285Ala). The mutant residues are conserved across all AChR subunits of all species and are components of a valine ring in the channel pore, which is positioned four residues above the leucine ring. Both βV266A and εV265A reduce the amino acid size and lengthen the channel opening bursts by fourfold by enhancing gating efficiency by approximately 30-fold. Substitution of alanine for valine at the corresponding position in the δ and α subunit prolongs the burst duration four- and eightfold, respectively. Replacing valine at ε codon 265 either by a still smaller glycine or by a larger leucine also lengthens the burst duration. Our analysis reveals that each valine in the valine ring contributes to channel kinetics equally, and the valine ring has been optimized in the course of evolution to govern channel gating.

  8. An Insight to Covert Channels

    OpenAIRE

    Salwan, Nitish; Singh, Sandeep; Arora, Suket; Singh, Amarpreet

    2013-01-01

    This paper presents an overview of different concepts regarding covert channels. It discusses the various classifications and the detailing of various fields used to manipulate for the covert channel execution.Different evaluation criterias are presented for measuring the strength of covert channels. The defenses and prevention schemes for this covert channel will also be discussed. This paper also discuss about an advanced timing channel i.e.Temperature Based Covert Channel.

  9. Channel Choice: A Literature Review

    DEFF Research Database (Denmark)

    Østergaard Madsen, Christian; Kræmmergaard, Pernille

    2015-01-01

    The channel choice branch of e-government studies citizens’ and businesses’ choice of channels for interacting with government, and how government organizations can integrate channels and migrate users towards the most cost-efficient channels. In spite of the valuable contributions offered no sys...... no systematic overview exist of channel choice. We present a literature review of channel choice studies in government to citizen context identifying authors, countries, methods, concepts, units of analysis, and theories, and offer suggestionsfor future studies....

  10. Residue arithmetic in binary systems

    OpenAIRE

    Barsi, Ferruccio

    1988-01-01

    A natural approach to the problem of performing mod m computations in a binary system is presented and a solution is suggested which is based upon a straightforward relation between the residues of a same integer X with respect to different moduli. The proposed solution proves fruitful in various applications, such as converting binary integers to residue notation and mod m addition or multiplication. Even if the most usual implementation approach for mod m processors is based on look-up tabl...

  11. Ion Channels in Obesity: Pathophysiology and Potential Therapeutic Targets

    OpenAIRE

    LUIZ HENRIQUE CÉSAR VASCONCELOS; IARA LEÃO LUNA DE SOUZA; LILIAN SOUSA PINHEIRO; BAGNÓLIA ARAÚJO DA SILVA

    2016-01-01

    Obesity is a multifactorial disease related to metabolic disorders and associated with genetic determinants. Currently, ion channels activity has been linked to many of these disorders, in addition to the central regulation of food intake, energetic balance, hormone release and response, as well as the adipocyte cell proliferation. Therefore, the objective of this work is to review the current knowledge about the influence of ion channels in obesity development. This review used different sou...

  12. Kv1 channels and neural processing in vestibular calyx afferents

    Directory of Open Access Journals (Sweden)

    Frances L Meredith

    2015-06-01

    Full Text Available Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to α-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K+ channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K+ channels could help alleviate vestibular dysfunction on earth and in space.

  13. Marine Tar Residues: a Review.

    Science.gov (United States)

    Warnock, April M; Hagen, Scott C; Passeri, Davina L

    Marine tar residues originate from natural and anthropogenic oil releases into the ocean environment and are formed after liquid petroleum is transformed by weathering, sedimentation, and other processes. Tar balls, tar mats, and tar patties are common examples of marine tar residues and can range in size from millimeters in diameter (tar balls) to several meters in length and width (tar mats). These residues can remain in the ocean environment indefinitely, decomposing or becoming buried in the sea floor. However, in many cases, they are transported ashore via currents and waves where they pose a concern to coastal recreation activities, the seafood industry and may have negative effects on wildlife. This review summarizes the current state of knowledge on marine tar residue formation, transport, degradation, and distribution. Methods of detection and removal of marine tar residues and their possible ecological effects are discussed, in addition to topics of marine tar research that warrant further investigation. Emphasis is placed on benthic tar residues, with a focus on the remnants of the Deepwater Horizon oil spill in particular, which are still affecting the northern Gulf of Mexico shores years after the leaking submarine well was capped.

  14. Structures, Mixed Types - Residual Waste Operations

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — A Residual Waste Operation is a DEP primary facility type related to the Waste Management Residual Waste Program. Residual waste is waste generated at an industrial,...

  15. Cooperative gating between ion channels.

    Science.gov (United States)

    Choi, Kee-Hyun

    2014-01-01

    Cooperative gating between ion channels, i.e. the gating of one channel directly coupled to the gating of neighboring channels, has been observed in diverse channel types at the single-channel level. Positively coupled gating could enhance channel-mediated signaling while negative coupling may effectively reduce channel gating noise. Indeed, the physiological significance of cooperative channel gating in signal transduction has been recognized in several in vivo studies. Moreover, coupled gating of ion channels was reported to be associated with some human disease states. In this review, physiological roles for channel cooperativity and channel clustering observed in vitro and in vivo are introduced, and stimulation-induced channel clustering and direct channel cross linking are suggested as the physical mechanisms of channel assembly. Along with physical clustering, several molecular mechanisms proposed as the molecular basis for functional coupling of neighboring channels are covered: permeant ions as a channel coupling mediator, concerted channel activation through the membrane, and allosteric mechanisms. Also, single-channel analysis methods for cooperative gating such as the binomial analysis, the variance analysis, the conditional dwell time density analysis, and the maximum likelihood fitting analysis are reviewed and discussed.

  16. Sensing with Ion Channels

    CERN Document Server

    Martinac, Boris

    2008-01-01

    All living cells are able to detect and translate environmental stimuli into biologically meaningful signals. Sensations of touch, hearing, sight, taste, smell or pain are essential to the survival of all living organisms. The importance of sensory input for the existence of life thus justifies the effort made to understand its molecular origins. Sensing with Ion Channels focuses on ion channels as key molecules enabling biological systems to sense and process the physical and chemical stimuli that act upon cells in their living environment. Its aim is to serve as a reference to ion channel specialists and as a source of new information to non specialists who want to learn about the structural and functional diversity of ion channels and their role in sensory physiology.

  17. Covert Channels within IRC

    Science.gov (United States)

    2011-03-24

    Communications ....................................... 2 1.3 Steganography and Covert Channels .......................................................... 3...Internet Relay Chat ..................................................................................... 7 2.2 Steganography ...13 2.2.2 Encrypted Steganographic Systems .............................................. 15 2.2.3 Text-Based Steganography

  18. Channelized Streams in Iowa

    Data.gov (United States)

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

  19. Authentication over Noisy Channels

    CERN Document Server

    Lai, Lifeng; Poor, H Vincent

    2008-01-01

    In this work, message authentication over noisy channels is studied. The model developed in this paper is the authentication theory counterpart of Wyner's wiretap channel model. Two types of opponent attacks, namely impersonation attacks and substitution attacks, are investigated for both single message and multiple message authentication scenarios. For each scenario, information theoretic lower and upper bounds on the opponent's success probability are derived. Remarkably, in both scenarios, lower and upper bounds are shown to match, and hence the fundamental limit of message authentication over noisy channels is fully characterized. The opponent's success probability is further shown to be smaller than that derived in the classic authentication model in which the channel is assumed to be noiseless. These results rely on a proposed novel authentication scheme in which key information is used to provide simultaneous protection again both types of attacks.

  20. Cl- channels in apoptosis

    DEFF Research Database (Denmark)

    Wanitchakool, Podchanart; Ousingsawat, Jiraporn; Sirianant, Lalida

    2016-01-01

    , and cystic fibrosis transmembrane conductance regulator (CFTR) in cellular apoptosis. LRRC8A-E has been identified as a volume-regulated anion channel expressed in many cell types. It was shown to be required for regulatory and apoptotic volume decrease (RVD, AVD) in cultured cell lines. Its presence also......(-) channels or as regulators of other apoptotic Cl(-) channels, such as LRRC8. CFTR has been known for its proapoptotic effects for some time, and this effect may be based on glutathione release from the cell and increase in cytosolic reactive oxygen species (ROS). Although we find that CFTR is activated...... by cell swelling, it is possible that CFTR serves RVD/AVD through accumulation of ROS and activation of independent membrane channels such as ANO6. Thus activation of ANO6 will support cell shrinkage and induce additional apoptotic events, such as membrane phospholipid scrambling....

  1. Volume Regulated Channels

    DEFF Research Database (Denmark)

    Klausen, Thomas Kjær

    - serves a multitude of functions in the mammalian cell, regulating the membrane potential (Em), cell volume, protein activity and the driving force for facilitated transporters giving Cl- and Cl- channels a major potential of regulating cellular function. These functions include control of the cell cycle...... of volume perturbations evolution have developed system of channels and transporters to tightly control volume homeostasis. In the past decades evidence has been mounting, that the importance of these volume regulated channels and transporters are not restricted to the defense of cellular volume......, controlled cell death and cellular migration. Volume regulatory mechanisms has long been in focus for regulating cellular proliferation and my thesis work have been focusing on the role of Cl- channels in proliferation with specific emphasis on ICl, swell. Pharmacological blockage of the ubiquitously...

  2. Mutations of the S4-S5 linker alter activation properties of HERG potassium channels expressed in Xenopus oocytes.

    Science.gov (United States)

    Sanguinetti, M C; Xu, Q P

    1999-02-01

    1. The structural basis for the activation gate of voltage-dependent K+ channels is not known, but indirect evidence has implicated the S4-S5 linker, the cytoplasmic region between the fourth and fifth transmembrane domains of the channel subunit. We have studied the effects of mutations in the S4-S5 linker of HERG (human ether-á-go-go-related gene), a human delayed rectifier K+ channel, in Xenopus oocytes. 2. Mutation of acidic residues (D540, E544) in the S4-S5 linker of HERG channels to neutral (Ala) or basic (Lys) residues accelerated the rate of channel deactivation. Most mutations greatly accelerated the rate of activation. However, E544K HERG channels activated more slowly than wild-type HERG channels. 3. Mutation of residues in the S4-S5 linker had little or no effect on fast inactivation, consistent with independence of HERG channel activation and inactivation 4. In response to large hyperpolarizations, D540K HERG channels can reopen into a state that is distinct from the normal depolarization-induced open state. It is proposed that substitution of a negatively charged Asp with the positively charged Lys disrupts a subunit interaction that normally stabilizes the channel in a closed state at negative transmembrane potentials. 5. The results indicate that the S4-S5 linker is a crucial component of the activation gate of HERG channels.

  3. Chloride channels in stroke

    Institute of Scientific and Technical Information of China (English)

    Ya-ping ZHANG; Hao ZHANG; Dayue Darrel DUAN

    2013-01-01

    Vascular remodeling of cerebral arterioles,including proliferation,migration,and apoptosis of vascular smooth muscle cells (VSMCs),is the major cause of changes in the cross-sectional area and diameter of the arteries and sudden interruption of blood flow or hemorrhage in the brain,ie,stroke.Accumulating evidence strongly supports an important role for chloride (Clˉ) channels in vascular remodeling and stroke.At least three Clˉ channel genes are expressed in VSMCs:1) the TMEM16A (or Ano1),which may encode the calcium-activated Clˉ channels (CACCs); 2) the CLC-3 Clˉ channel and Clˉ/H+ antiporter,which is closely related to the volume-regulated Clˉ channels (VRCCs); and 3) the cystic fibrosis transmembrane conductance regulator (CFTR),which encodes the PKA-and PKC-activated Clˉ channels.Activation of the CACCs by agonist-induced increase in intracellular Ca2+ causes membrane depolarization,vasoconstriction,and inhibition of VSMC proliferation.Activation of VRCCs by cell volume increase or membrane stretch promotes the production of reactive oxygen species,induces proliferation and inhibits apoptosis of VSMCs.Activation of CFTR inhibits oxidative stress and may prevent the development of hypertension.In addition,Clˉ current mediated by gammaaminobutyric acid (GABA) receptor has also been implicated a role in ischemic neuron death.This review focuses on the functional roles of Clˉ channels in the development of stroke and provides a perspective on the future directions for research and the potential to develop Clˉ channels as new targets for the prevention and treatment of stroke.

  4. The S4-S5 linker couples voltage sensing and activation of pacemaker channels.

    Science.gov (United States)

    Chen, J; Mitcheson, J S; Tristani-Firouzi, M; Lin, M; Sanguinetti, M C

    2001-09-25

    Voltage-gated channels are normally opened by depolarization and closed by repolarization of the membrane. Despite sharing significant sequence homology with voltage-gated K(+) channels, the gating of hyperpolarization-activated, cyclic-nucleotide-gated (HCN) pacemaker channels has the opposite dependence on membrane potential: hyperpolarization opens, whereas depolarization closes, these channels. The mechanism and structural basis of the process that couples voltage sensor movement to HCN channel opening and closing is not understood. On the basis of our previous studies of a mutant HERG (human ether-a-go-go-related gene) channel, we hypothesized that the intracellular linker that connects the fourth and fifth transmembrane domains (S4-S5 linker) of HCN channels might be important for channel gating. Here, we used alanine-scanning mutagenesis of the HCN2 S4-S5 linker to identify three residues, E324, Y331, and R339, that when mutated disrupted normal channel closing. Mutation of a basic residue in the S4 domain (R318Q) prevented channel opening, presumably by disrupting S4 movement. However, channels with R318Q and Y331S mutations were constitutively open, suggesting that these channels can open without a functioning S4 domain. We conclude that the S4-S5 linker mediates coupling between voltage sensing and HCN channel activation. Our findings also suggest that opening of HCN and related channels corresponds to activation of a gate located near the inner pore, rather than recovery of channels from a C-type inactivated state.

  5. DISSOLUTION OF NEPTUNIUM OXIDE RESIDUES

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E

    2009-01-12

    This report describes the development of a dissolution flowsheet for neptunium (Np) oxide (NpO{sub 2}) residues (i.e., various NpO{sub 2} sources, HB-Line glovebox sweepings, and Savannah River National Laboratory (SRNL) thermogravimetric analysis samples). Samples of each type of materials proposed for processing were dissolved in a closed laboratory apparatus and the rate and total quantity of off-gas were measured. Samples of the off-gas were also analyzed. The quantity and type of solids remaining (when visible) were determined after post-dissolution filtration of the solution. Recommended conditions for dissolution of the NpO{sub 2} residues are: Solution Matrix and Loading: {approx}50 g Np/L (750 g Np in 15 L of dissolver solution), using 8 M nitric acid (HNO{sub 3}), 0.025 M potassium fluoride (KF) at greater than 100 C for at least 3 hours. Off-gas: Analysis of the off-gas indicated nitric oxide (NO), nitrogen dioxide (NO{sub 2}) and nitrous oxide (N{sub 2}O) as the only identified components. No hydrogen (H{sub 2}) was detected. The molar ratio of off-gas produced per mole of Np dissolved ranged from 0.25 to 0.4 moles of gas per mole of Np dissolved. A peak off-gas rate of {approx}0.1 scfm/kg bulk oxide was observed. Residual Solids: Pure NpO{sub 2} dissolved with little or no residue with the proposed flowsheet but the NpCo and both sweepings samples left visible solid residue after dissolution. For the NpCo and Part II Sweepings samples the residue amounted to {approx}1% of the initial material, but for the Part I Sweepings sample, the residue amounted to {approx}8 % of the initial material. These residues contained primarily aluminum (Al) and silicon (Si) compounds that did not completely dissolve under the flowsheet conditions. The residues from both sweepings samples contained minor amounts of plutonium (Pu) particles. Overall, the undissolved Np and Pu particles in the residues were a very small fraction of the total solids.

  6. Evaluation of residue-residue contact prediction in CASP10

    KAUST Repository

    Monastyrskyy, Bohdan

    2013-08-31

    We present the results of the assessment of the intramolecular residue-residue contact predictions from 26 prediction groups participating in the 10th round of the CASP experiment. The most recently developed direct coupling analysis methods did not take part in the experiment likely because they require a very deep sequence alignment not available for any of the 114 CASP10 targets. The performance of contact prediction methods was evaluated with the measures used in previous CASPs (i.e., prediction accuracy and the difference between the distribution of the predicted contacts and that of all pairs of residues in the target protein), as well as new measures, such as the Matthews correlation coefficient, the area under the precision-recall curve and the ranks of the first correctly and incorrectly predicted contact. We also evaluated the ability to detect interdomain contacts and tested whether the difficulty of predicting contacts depends upon the protein length and the depth of the family sequence alignment. The analyses were carried out on the target domains for which structural homologs did not exist or were difficult to identify. The evaluation was performed for all types of contacts (short, medium, and long-range), with emphasis placed on long-range contacts, i.e. those involving residues separated by at least 24 residues along the sequence. The assessment suggests that the best CASP10 contact prediction methods perform at approximately the same level, and comparably to those participating in CASP9.

  7. Fracture channel waves

    Science.gov (United States)

    Nihei, Kurt T.; Yi, Weidong; Myer, Larry R.; Cook, Neville G. W.; Schoenberg, Michael

    1999-03-01

    The properties of guided waves which propagate between two parallel fractures are examined. Plane wave analysis is used to obtain a dispersion equation for the velocities of fracture channel waves. Analysis of this equation demonstrates that parallel fractures form an elastic waveguide that supports two symmetric and two antisymmetric dispersive Rayleigh channel waves, each with particle motions and velocities that are sensitive to the normal and tangential stiffnesses of the fractures. These fracture channel waves degenerate to shear waves when the fracture stiffnesses are large, to Rayleigh waves and Rayleigh-Lamb plate waves when the fracture stiffnesses are low, and to fracture interface waves when the fractures are either very closely spaced or widely separated. For intermediate fracture stiffnesses typical of fractured rock masses, fracture channel waves are dispersive and exhibit moderate to strong localization of guided wave energy between the fractures. The existence of these waves is examined using laboratory acoustic measurements on a fractured marble plate. This experiment confirms the distinct particle motion of the fundamental antisymmetric fracture channel wave (A0 mode) and demonstrates the ease with which a fracture channel wave can be generated and detected.

  8. Course on Ionic Channels

    CERN Document Server

    1986-01-01

    This book is based on a series of lectures for a course on ionic channels held in Santiago, Chile, on November 17-20, 1984. It is intended as a tutorial guide on the properties, function, modulation, and reconstitution of ionic channels, and it should be accessible to graduate students taking their first steps in this field. In the presentation there has been a deliberate emphasis on the spe­ cific methodologies used toward the understanding of the workings and function of channels. Thus, in the first section, we learn to "read" single­ channel records: how to interpret them in the theoretical frame of kinetic models, which information can be extracted from gating currents in re­ lation to the closing and opening processes, and how ion transport through an open channel can be explained in terms of fluctuating energy barriers. The importance of assessing unequivocally the origin and purity of mem­ brane preparations and the use of membrane vesicles and optical tech­ niques in the stUGY of ionic channels a...

  9. Selective transmission and channel estimation in massive MIMO systems

    Institute of Scientific and Technical Information of China (English)

    杨睿哲

    2016-01-01

    Massive MIMO systems have got extraordinary spectral efficiency using a large number of base station antennas, but it is in the challenge of pilot contamination using the aligned pilots.To address this issue, a selective transmission is proposed using time-shifted pilots with cell grouping, where the strong interfering users in downlink transmission cells are temporally stopped during the pilots transmission in uplink cells.Based on the spatial characteristics of physical channel models, the strong interfering users are selected to minimize the inter-cell interference and the cell grouping is designed to have less temporally stopped users within a smaller area.Furthermore, a Kalman estima-tor is proposed to reduce the unexpected effect of residual interferences in channel estimation, which exploits both the spatial-time correlation of channels and the share of the interference information. The numerical results show that our scheme significantly improves the channel estimation accuracy and the data rates.

  10. Geographic variation in Puget Sound tidal channel planform geometry

    Science.gov (United States)

    Hood, W. Gregory

    2015-02-01

    Tidal channels are central elements of salt marsh hydrodynamics, sediment dynamics, and habitat. To develop allometric models predicting the number and size of tidal channels that could develop following salt marsh restoration, channels were digitized from aerial photographs of Puget Sound river delta marshes. Salt marsh area was the independent variable for all dependent channel planform metrics. Tidal channel allometry showed similar scaling exponents for channel planform metrics throughout Puget Sound, simplifying comparisons between locations. Y-intercepts of allometric relationships showed geographic variation, which multiple-regression indicated was associated with tidal range and storm significant wave height. Channel size and complexity were positively related to tidal range and negatively related to wave height. Four case studies, each with paired regions of similar tidal range and contrasting wave environments, further indicated wave environment affected channel geometry. Wave-mediated sediment delivery may be the mechanism involved, with wave-sheltered areas experiencing relative sediment deficits, such that some salt marshes in Puget Sound are already suffering sea-level rise impacts that are reflected in their channel network geometry.

  11. Ion Channels in Obesity: Pathophysiology and Potential Therapeutic Targets.

    Science.gov (United States)

    Vasconcelos, Luiz H C; Souza, Iara L L; Pinheiro, Lílian S; Silva, Bagnólia A

    2016-01-01

    Obesity is a multifactorial disease related to metabolic disorders and associated with genetic determinants. Currently, ion channels activity has been linked to many of these disorders, in addition to the central regulation of food intake, energetic balance, hormone release and response, as well as the adipocyte cell proliferation. Therefore, the objective of this work is to review the current knowledge about the influence of ion channels in obesity development. This review used different sources of literature (Google Scholar, PubMed, Scopus, and Web of Science) to assess the role of ion channels in the pathophysiology of obesity. Ion channels present diverse key functions, such as the maintenance of physiological homeostasis and cell proliferation. Cell biology and pharmacological experimental evidences demonstrate that proliferating cells exhibit ion channel expression, conductance, and electrical properties different from the resting cells. Thereby, a large variety of ion channels has been identified in the pathogenesis of obesity such as potassium, sodium, calcium and chloride channels, nicotinic acetylcholine receptor and transient receptor potential channels. The fundamental involvement of these channels on the generation of obesity leads to the progress in the knowledge about the mechanisms responsible for the obesity pathophysiology, consequently emerging as new targets for pharmacological modulation.

  12. Ion Channels in Obesity: Pathophysiology and Potential Therapeutic Targets

    Directory of Open Access Journals (Sweden)

    LUIZ HENRIQUE CÉSAR VASCONCELOS

    2016-03-01

    Full Text Available Obesity is a multifactorial disease related to metabolic disorders and associated with genetic determinants. Currently, ion channels activity has been linked to many of these disorders, in addition to the central regulation of food intake, energetic balance, hormone release and response, as well as the adipocyte cell proliferation. Therefore, the objective of this work is to review the current knowledge about the influence of ion channels in obesity development. This review used different sources of literature (Google Scholar, PubMed, Scopus and Web of Science to assess the role of ion channels in the pathophysiology of obesity. Ion channels present diverse key functions, such as the maintenance of physiological homeostasis and cell proliferation. Cell biology and pharmacological experimental evidences demonstrate that proliferating cells exhibit ion channel expression, conductance and electrical properties different from the resting cells. Thereby, a large variety of ion channels has been identified in the pathogenesis of obesity such as potassium, sodium, calcium and chloride channels, nicotinic acetylcholine receptor and transient receptor potential channels. The fundamental involvement of these channels on the generation of obesity leads to the progress in the knowledge about the mechanisms responsible for the obesity pathophysiology, consequently emerging as new targets for pharmacological modulation.

  13. Coordination Mechanisms Based on Strategic Innovative Compensation in Dual-Channel Supply Chains%考虑创新补偿的双渠道供应链协调机制研究

    Institute of Scientific and Technical Information of China (English)

    陈树桢; 熊中楷; 李根道; 文海鸿

    2011-01-01

    movement of retailers. We also analyze and compare strategic movements of manufacturers and retailers.In the first part, we study and compare two business cases between a decentralized manufacturer using innovative compensation strategy, and another manufacturer not using this strategy. These two case studies show that the faster the initial distribution cost of the retailer channel declines, the higher the optimal level of investment that a manufacturer is more willing to compensate for its retailer's innovative compensation. A manufacturer will increase its wholesale price and keep the online channel price as before to balance the investment cost of retailers. A retailer will increase investment in channel innovation and reduce its retail price at the same time. Both manufacturers and retailers can benefit from a manufacturer's compensation investment. In addition, we discuss and compare innovative compensation investment under centralized and decentralize decision-making processes. In the centralized decision making process, the retailer price is always the lowest when the online price remains the same. This finding is contrary to our expectations. With the decentralized decision-making process, the entire supply chain always has the highest profit and manufacturers have the highest investment in innovation activities. With the decentralized decision making process, a manufacturer has an incentive to design mechanisms to coordinate with retailers to benefit both parties.In the second part, we examine ways to adjust manufacturer-retailer relationships using two-part tariffs. Some cases show that twopart tariffs can coordinate traditional channels by turning a retailer into a “residual claimant” of channel profits. However, the “residual clamant” mechanism breaks down in the dual-channel model. Unexpectedly, two-part tariffs can coordinate the dual-channel model and a manufacturer can effectively set its wholesale price and fix fees at the right level. At the same

  14. Residual stresses in welded plates

    Science.gov (United States)

    Bernstein, Edward L.

    1994-01-01

    The purpose of this project was to develop a simple model which could be used to study residual stress. The mechanism that results in residual stresses in the welding process starts with the deposition of molten weld metal which heats the immediately adjacent material. After solidification of weld material, normal thermal shrinkage is resisted by the adjacent, cooler material. When the thermal strain exceeds the elastic strain corresponding to the yield point stress, the stress level is limited by this value, which decreases with increasing temperature. Cooling then causes elastic unloading which is restrained by the adjoining material. Permanent plastic strain occurs, and tension is caused in the region immediately adjacent to the weld material. Compression arises in the metal farther from the weld in order to maintain overall static equilibrium. Subsequent repair welds may add to the level of residual stresses. The level of residual stress is related to the onset of fracture during welding. Thus, it is of great importance to be able to predict the level of residual stresses remaining after a weld procedure, and to determine the factors, such as weld speed, temperature, direction, and number of passes, which may affect the magnitude of remaining residual stress. It was hoped to use traditional analytical modeling techniques so that it would be easier to comprehend the effect of these variables on the resulting stress. This approach was chosen in place of finite element methods so as to facilitate the understanding of the physical processes. The accuracy of the results was checked with some existing experimental studies giving residual stress levels found from x-ray diffraction measurements.

  15. Mutational analysis of the structure basis for the multimerization function of NifA central domain

    Institute of Scientific and Technical Information of China (English)

    YANG; Chengtao; (杨成涛); YU; Guanqiao; (俞冠翘); SHEN; Shanjiong; (San-Chiun; Shen,; 沈善炯); ZHU; Jiabi; (朱家璧)

    2001-01-01

    In Klebsiella pneumoniae (Kp) NifA central domain, when the conservative amino acid residue Thr-290 in C3 region was replaced by Val, the function of NifA for activating the transcription of nif genes was lost. Thus the conservative Thr-290 residue seems critical for the activation function of NifA central domain. This point mutant of NifA central domain is used to examine the putative multimerization function of NifA central domain by merodiploid experiment. The results showed that the NifA central domain bore the multimerization determinants of NifA protein. A series of truncated mutants of NifA were constructed to determine the structural elements at the central domain critical for multimerization. It demonstrates that amino acid residues 252-453 are involved in the multimerization function of NifA central domain.

  16. Mutational analysis of the structure basis for the multimerization function of NifA central domain

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In Klebsiella pneumoniae (Kp) NifA central domain, when theconservative amino acid residue Thr-290 in C3 region was replaced by Val, the function of NifA for activating the transcription of nif genes was lost. Thus the conservative Thr-290 residue seems critical for the activation function of NifA central domain. This point mutant of NifA central domain is used to examine the putative multimerization function of NifA central domain by merodiploid experiment. The results showed that the NifA central domain bore the multimerization determinants of NifA protein. A series of truncated mutants of NifA were constructed to determine the structural elements at the central domain critical for multimerization. It demonstrates that amino acid residues 252-453 are involved in the multimerization function of NifA central domain.

  17. Contributions of conserved residues at the gating interface of glycine receptors

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Leung, Ada W Y; Galpin, Jason D

    2011-01-01

    Glycine receptors (GlyRs) are chloride channels that mediate fast inhibitory neurotransmission and are members of the pentameric ligand-gated ion channel (pLGIC) family. The interface between the ligand binding domain and the transmembrane domain of pLGICs has been proposed to be crucial for chan......Glycine receptors (GlyRs) are chloride channels that mediate fast inhibitory neurotransmission and are members of the pentameric ligand-gated ion channel (pLGIC) family. The interface between the ligand binding domain and the transmembrane domain of pLGICs has been proposed to be crucial...... in the pre-M1 domain that is crucial for channel gating. We further propose that Phe-145 and Phe-187 play important roles in stabilizing this interaction by providing a hydrophobic environment. In contrast to the equivalent residues in loop 2 of other pLGICs, the negative charge at Glu-53 α1 Gly...

  18. Solid State NMR Observation of Phenylalanine Residues in M2 Protein from Influenza a Virus

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ The M2 protein from influenza A functions as a proton channel. It has been cloned and over-expressed in Escherchia coli. Large quantities of recombinant protein are purified by Ni2 affinity chromatography. The residues in M2 have been selectively labeled with 15N in an aromatic amino acid autotroph CT19.

  19. Acid-sensing ion channels and migraine

    Directory of Open Access Journals (Sweden)

    Yu-qi KANG

    2015-09-01

    Full Text Available Acid-sensing ion channels (ASICs are ligand-gated ion channels that are activated by extracellular protons (H+, which belong to epithelial sodium channels/degenerin (ENaC/DEG superfamily. ASICs are widely distributed in central nervous system, peripheral nervous system, digestive system and some tumor tissues. Different ASIC subunits play important roles in various pathophysiological processes such as touch, sour taste, learning and memory, including inflammation, ischemic stroke, pain, learning and memory decline, epilepsy, multiple sclerosis (MS, migraine, irritable bowel syndrome and tumor. Research over the last 2 decades has achieved substantial advances in migraine pathophysiology. It is now largely accepted that inflammatory pathways play a key role and three main events seem to take place: cortical spreading depression (CSD, activation of the trigeminovascular system (i.e. dural nociceptors, peripheral and central sensitization of this pain pathway. However, the exact mechanisms that link these three events to each other and to inflammation have so far remained to be studied. This article takes an overview of newly research advances in structure, distribution and the relationship with migraine of ASICs.  DOI: 10.3969/j.issn.1672-6731.2015.09.013

  20. The role of CRAC channel in asthma.

    Science.gov (United States)

    Kaur, Manminder; Birrell, Mark A; Dekkak, Bilel; Reynolds, Sophie; Wong, Sissie; De Alba, Jorge; Raemdonck, Kristof; Hall, Simon; Simpson, Karen; Begg, Malcolm; Belvisi, Maria G; Singh, Dave

    2015-12-01

    Asthma is increasing globally and current treatments only manage a proportion of patients. There is an urgent need to develop new therapies. Lymphocytes are thought to play a central role in the pathophysiology of asthma through the production of inflammatory mediators. This is thought to be via the transcription factor NFAT which in turn can be activated through Ca(2+) release-activated Ca(2+) (CRAC) channels. The aim of this work was to investigate the role of CRAC in clinical and pre-clinical models of allergic asthma. Initial data demonstrated that the NFAT pathway is increased in stimulated lymphocytes from asthmatics. To confirm a role for the channel we showed that a selective inhibitor, Synta 66, blocked mediator production from lymphocytes. Synta 66 inhibited CD2/3/28 induced IL-2, IL-7, IL-13 & IFNΥ in a concentration-dependent manner in healthy and severe asthma donors, with over 60% inhibition observed for all cytokines. NFAT pathway was also increased in a pre-clinical asthma model. In this model we have demonstrated that CRAC played a central role in the airway inflammation and late asthmatic response (LAR). In conclusion, our data provides evidence that suggests targeting CRAC channels could be of therapeutic benefit for asthma sufferers.

  1. Dry fermentation of agricultural residues

    Science.gov (United States)

    Jewell, W. J.; Chandler, J. A.; Dellorto, S.; Fanfoni, K. J.; Fast, S.; Jackson, D.; Kabrick, R. M.

    1981-09-01

    A dry fermentation process is discussed which converts agricultural residues to methane, using the residues in their as produced state. The process appears to simplify and enhance the possibilities for using crop residues as an energy source. The major process variables investigated include temperature, the amount and type of inoculum, buffer requirements, compaction, and pretreatment to control the initial available organic components that create pH problems. A pilot-scale reactor operation on corn stover at a temperature of 550 C, with 25 percent initial total solids, a seed-to-feed ratio of 2.5 percent, and a buffer-to-feed ratio of 8 percent achieved 33 percent total volatile solids destruction in 60 days. Volumetric biogas yields from this unit were greater than 1 vol/vol day for 12 days, and greater than 0.5 vol/vol day for 32 days, at a substrate density of 169 kg/m (3).

  2. MIMO Transmission with Residual Transmit-RF Impairments

    CERN Document Server

    Studer, Christoph; Burg, Andreas

    2010-01-01

    Physical transceiver implementations for multiple-input multiple-output (MIMO) wireless communication systems suffer from transmit-RF (Tx-RF) impairments. In this paper, we study the effect on channel capacity and error-rate performance of residual Tx-RF impairments that defy proper compensation. In particular, we demonstrate that such residual distortions severely degrade the performance of (near-)optimum MIMO detection algorithms. To mitigate this performance loss, we propose an efficient algorithm, which is based on an i.i.d. Gaussian model for the distortion caused by these impairments. In order to validate this model, we provide measurement results based on a 4-stream Tx-RF chain implementation for MIMO orthogonal frequency-division multiplexing (OFDM).

  3. MEMS in microfluidic channels.

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-03-01

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

  4. The transient receptor potential family of ion channels.

    Science.gov (United States)

    Nilius, Bernd; Owsianik, Grzegorz

    2011-01-01

    The transient receptor potential (TRP) multigene superfamily encodes integral membrane proteins that function as ion channels. Members of this family are conserved in yeast, invertebrates and vertebrates. The TRP family is subdivided into seven subfamilies: TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), TRPA (ankyrin) and TRPN (NOMPC-like); the latter is found only in invertebrates and fish. TRP ion channels are widely expressed in many different tissues and cell types, where they are involved in diverse physiological processes, such as sensation of different stimuli or ion homeostasis. Most TRPs are non-selective cation channels, only few are highly Ca2+ selective, some are even permeable for highly hydrated Mg2+ ions. This channel family shows a variety of gating mechanisms, with modes of activation ranging from ligand binding, voltage and changes in temperature to covalent modifications of nucleophilic residues. Activated TRP channels cause depolarization of the cellular membrane, which in turn activates voltage-dependent ion channels, resulting in a change of intracellular Ca2+ concentration; they serve as gatekeeper for transcellular transport of several cations (such as Ca2+ and Mg2+), and are required for the function of intracellular organelles (such as endosomes and lysosomes). Because of their function as intracellular Ca2+ release channels, they have an important regulatory role in cellular organelles. Mutations in several TRP genes have been implicated in diverse pathological states, including neurodegenerative disorders, skeletal dysplasia, kidney disorders and pain, and ongoing research may help find new therapies for treatments of related diseases.

  5. Carbon monoxide: an emerging regulator of ion channels.

    Science.gov (United States)

    Wilkinson, William J; Kemp, Paul J

    2011-07-01

    Carbon monoxide is rapidly emerging as an important cellular messenger, regulating a wide range of physiological processes. Crucial to its role in both physiology and disease is its ability differentially to regulate several classes of ion channels, including examples from calcium-activated K(+) (BK(Ca)), voltage-activated K(+) (K(v)) and Ca(2+) channel (L-type) families, ligand-gated P2X receptors (P2X2 and P2X4), tandem P domain K(+) channels (TREK1) and the epithelial Na(+) channel (ENaC). The mechanisms by which CO regulates these ion channels are still unclear and remain somewhat controversial. However, available structure-function studies suggest that a limited range of amino acid residues confer CO sensitivity, either directly or indirectly, to particular ion channels and that cellular redox state appears to be important to the final integrated response. Whatever the molecular mechanism by which CO regulates ion channels, endogenous production of this gasotransmitter has physiologically important roles and is currently being explored as a potential therapeutic.

  6. Interferometric Measurement Of Residual Stress

    Science.gov (United States)

    Danyluk, Steven; Andonian, A. T.

    1990-01-01

    Stress averaged through thickness of plate measured nondestructively. Theory of elasticity combined with laser interferometric technique into technique for measurement of residual stresses in solid objects - usually in thin, nominally-flat plates. Measurements particularly useful in inspection of wafers of single-crystal silicon for making solar cells or integrated circuits, because stresses remaining after crystal-growing process cause buckling or fracture. Used to predict deflections of plates caused by known applied loads under specified boundary condition, or to infer applied loads that cause known deflections. Also used to relate known deflections to residual stresses equivalent to stresses produced by fictitious applied loads.

  7. Residual contact restraints in cryogenics

    Science.gov (United States)

    Cretegny, J. F.; Demonicault, J. M.

    The use of residual stress measurements to evaluate the state of cryogenic turbomachines, whose surfaces are worn by the working conductions in dry contact, is addressed. Their contribution to the understanding of the reasons of possible ruptures is considered. It is stated that residual stress measurements should be used as a complementary tool rather than as input data for models. It is shown, thanks to two examples concerning the ball bearings and splines of the liquid hydrogen turbopump of the Vulcain engine, what can be expected from such techniques. Total exploitation of the results has still to be done, but preliminary results are quite encouraging.

  8. The Earliest Ion Channels in Protocellular Membranes

    Science.gov (United States)

    Mijajlovic, Milan; Pohorille, Andrew; Wilson, Michael; Wei, Chenyu

    2010-01-01

    Cellular membranes with their hydrophobic interior are virtually impermeable to ions. Bulk of ion transport through them is enabled through ion channels. Ion channels of contemporary cells are complex protein molecules which span the membrane creating a cylindrical pore filled with water. Protocells, which are widely regarded as precursors to modern cells, had similarly impermeable membranes, but the set of proteins in their disposal was much simpler and more limited. We have been, therefore, exploring an idea that the first ion channels in protocellular membranes were formed by much smaller peptide molecules that could spontaneously selfassemble into short-lived cylindrical bundles in a membrane. Earlier studies have shown that a group of peptides known as peptaibols is capable of forming ion channels in lipid bilayers when they are exposed to an electric field. Peptaibols are small, non-genetically encoded peptides produced by some fungi as a part of their system of defense against bacteria. They are usually only 14-20 residues long, which is just enough to span the membrane. Their sequence is characterized by the presence of non-standard amino acids which, interestingly, are also expected to have existed on the early earth. In particular, the presence of 2-aminoisobutyric acid (AIB) gives peptaibols strong helix forming propensities. Association of the helices inside membranes leads to the formation of cylindrical bundles, typically containing 4 to 10 monomers. Although peptaibols are excellent candidates for models of the earliest ion channels their structures, which are stabilized only by van der Waals forces and occasional hydrogen bonds between neighboring helices, are not very stable. Although it might properly reflect protobiological reality, it is also a major obstacle in studying channel behavior. For this reason we focused on two members of the peptaibol family, trichotoxin and antiamoebin, which are characterized by a single conductance level. This

  9. Atomic structure of recombinant thaumatin II reveals flexible conformations in two residues critical for sweetness and three consecutive glycine residues.

    Science.gov (United States)

    Masuda, Tetsuya; Mikami, Bunzo; Tani, Fumito

    2014-11-01

    Thaumatin, an intensely sweet-tasting protein used as a sweetener, elicits a sweet taste at 50 nM. Although two major variants designated thaumatin I and thaumatin II exist in plants, there have been few dedicated thaumatin II structural studies and, to date, data beyond atomic resolution had not been obtained. To identify the detailed structural properties explaining why thaumatin elicits a sweet taste, the structure of recombinant thaumatin II was determined at the resolution of 0.99 Å. Atomic resolution structural analysis with riding hydrogen atoms illustrated the differences in the direction of the side-chains more precisely and the electron density maps of the C-terminal regions were markedly improved. Though it had been suggested that the three consecutive glycine residues (G142-G143-G144) have highly flexible conformations, G143, the central glycine residue was successfully modelled in two conformations for the first time. Furthermore, the side chain r.m.s.d. values for two residues (R67 and R82) critical for sweetness exhibited substantially higher values, suggesting that these residues are highly disordered. These results demonstrated that the flexible conformations in two critical residues favoring their interaction with sweet taste receptors are prominent features of the intensely sweet taste of thaumatin.

  10. TRP channels and pain.

    Science.gov (United States)

    Julius, David

    2013-01-01

    Nociception is the process whereby primary afferent nerve fibers of the somatosensory system detect noxious stimuli. Pungent irritants from pepper, mint, and mustard plants have served as powerful pharmacological tools for identifying molecules and mechanisms underlying this initial step of pain sensation. These natural products have revealed three members of the transient receptor potential (TRP) ion channel family--TRPV1, TRPM8, and TRPA1--as molecular detectors of thermal and chemical stimuli that activate sensory neurons to produce acute or persistent pain. Analysis of TRP channel function and expression has validated the existence of nociceptors as a specialized group of somatosensory neurons devoted to the detection of noxious stimuli. These studies are also providing insight into the coding logic of nociception and how specification of nociceptor subtypes underlies behavioral discrimination of noxious thermal, chemical, and mechanical stimuli. Biophysical and pharmacological characterization of these channels has provided the intellectual and technical foundation for developing new classes of analgesic drugs.

  11. Dequantization Via Quantum Channels

    Science.gov (United States)

    Andersson, Andreas

    2016-10-01

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

  12. Chaos in quantum channels

    CERN Document Server

    Hosur, Pavan; Roberts, Daniel A; Yoshida, Beni

    2015-01-01

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

  13. 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.

  14. K(v)7 channels: function, pharmacology and channel modulators.

    Science.gov (United States)

    Dalby-Brown, William; Hansen, Henrik H; Korsgaard, Mads P G; Mirza, Naheed; Olesen, Søren-P

    2006-01-01

    K(v)7 channels are unique among K(+) channels, since four out of the five channel subtypes have well-documented roles in the development of human diseases. They have distinct physiological functions in the heart and in the nervous system, which can be ascribed to their voltage-gating properties. The K(v)7 channels also lend themselves to pharmacological modulation, and synthetic openers as well as blockers of the channels, regulating neuronal excitability, have existed even before the K(v)7 channels were identified by cloning. In the present review we give an account on the focused efforts to develop selective modulators, openers as well as blockers, of the K(v)7 channel subtypes, which have been undertaken during recent years, along with a discussion of the K(v)7 ion channel physiology and therapeutic indications for modulators of the neuronal K(v)7 channels.

  15. Ionic Channels in Thunderclouds

    Science.gov (United States)

    Losseva, T. V.; Fomenko, A. S.; Nemtchinov, I. V.

    2007-12-01

    We proceed to study the formation and propagation of ionic channels in thunderclouds in the framework of the model of the corona discharge wave propagation (Fomenko A.S., Losseva T.V., Nemtchinov I.V. The corona discharge waves in thunderclouds and formation of ionic channels // 2004 Fall Meeting. EOS Trans. AGU. 2004. V. 85. ¹ 47. Suppl. Abstract AE23A-0835.). In this model we proposed a hypothesis that the structure of a thundercloud becomes nonuniform due to corona discharge on the drops and ice particles and formation of ionic channels with higher conductivity than the surrounding air. When the onset strength of corona discharge becomes smaller than the electric field strength the corona discharge increases concentrations of ions in a small part of the cloud (a hot spot). An additional charge at opposite ends of the hot spot forms due to polarization process. The increased electric field initiates corona discharge in other parts of the cloud on ice particles and water drops with smaller sizes. The corona discharge front moves as a wave with the velocity of the order of ion drift and formes a highly conductive channel. We model this non-stationary problem with Poisson equation which is solved simultaneously with a simplified set of kinetic equations for ions, small charged particles and electrons (at high electric fields), including ionization due to electronic impact, attachment and formation of positive ions. By applying 3D numerical simulations we obtain the parameters of formed ionic channels with respect to onset electric fields both from large particles (in hot spot) and from small particles (surrounding hot spot), microscopic currents from particles with different sizes and the external electric field in the cloud. The interaction of ionic channels is also investigated. This work was supported by Russian Foundation of Basic Research (Project No 07-05-00998-à).

  16. TRESK potassium channel in human T lymphoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Miguel, Dénison Selene, E-mail: amurusk@hotmail.com [Center for Biomedical Research, University of Colima, Av. 25 de Julio 965, Villa San Sebastian, C.P. 28045 Colima (Mexico); García-Dolores, Fernando, E-mail: garciaddf@yahoo.com [Department of Pathology, Institute of Forensic Sciences, Av. Niños Héroes 130, Col. Doctores, C.P. 06720 Mexico, DF (Mexico); Rosa Flores-Márquez, María, E-mail: mariafo31@yahoo.com.mx [National Medical Center of Occident (CMNO) IMSS, Belisario Dominguez 735, Col. Independencia Oriente, C.P. 44340 Guadalajara, Jalisco (Mexico); Delgado-Enciso, Iván [University of Colima, School of Medicine, Av. Universidad 333, Col. Las Viboras, C.P. 28040 Colima (Mexico); Pottosin, Igor, E-mail: pottosin@ucol.mx [Center for Biomedical Research, University of Colima, Av. 25 de Julio 965, Villa San Sebastian, C.P. 28045 Colima (Mexico); Dobrovinskaya, Oxana, E-mail: oxana@ucol.mx [Center for Biomedical Research, University of Colima, Av. 25 de Julio 965, Villa San Sebastian, C.P. 28045 Colima (Mexico)

    2013-05-03

    Highlights: • TRESK (KCNK18) mRNA is present in different T lymphoblastic cell lines. • KCNK18 mRNA was not found in resting peripheral blood lymphocytes. • Clinical samples of T lymphoblastic leukemias and lymphomas were positive for TRESK. • TRESK in T lymphoblasts has dual localization, in plasma membrane and intracellular. -- Abstract: TRESK (TWIK-related spinal cord K{sup +}) channel, encoded by KCNK18 gene, belongs to the double-pore domain K{sup +} channel family and in normal conditions is expressed predominantly in the central nervous system. In our previous patch-clamp study on Jurkat T lymphoblasts we have characterized highly selective K{sup +} channel with pharmacological profile identical to TRESK. In the present work, the presence of KCNK18 mRNA was confirmed in T lymphoblastic cell lines (Jurkat, JCaM, H9) but not in resting peripheral blood lymphocytes of healthy donors. Positive immunostaining for TRESK was demonstrated in lymphoblastic cell lines, in germinal centers of non-tumoral lymph nodes, and in clinical samples of T acute lymphoblastic leukemias/lymphomas. Besides detection in the plasma membrane, intracellular TRESK localization was also revealed. Possible involvement of TRESK channel in lymphocyte proliferation and tumorigenesis is discussed.

  17. JZTX-IV, a unique acidic sodium channel toxin isolated from the spider Chilobrachys jingzhao.

    Science.gov (United States)

    Wang, Meichi; Diao, Jianbo; Li, Jiang; Tang, Jianzhou; Lin, Yin; Hu, Weijun; Zhang, Yongqun; Xiao, Yucheng; Liang, Songping

    2008-12-15

    Neurotoxins are important tools to explore the structure and function relationship of different ion channels. From the venom of Chinese spider Chilobrachys jingzhao, a novel toxin, Jingzhaotoxin-IV (JZTX-IV), is isolated and characterized. It consists of 34 amino acid residues including six acidic residues clustered with negative charge (pI=4.29). The full-length cDNA of JZTX-IV encodes an 86-amino acid precursor containing a signal peptide of 21 residues, a mature peptide of 34 residues and an intervening sequence of 29 residues with terminal Lys-Gly as the signal of amidation. Under whole-cell patch clamp conditions, JZTX-IV inhibits current and slows the inactivation of sodium channels by shifting the voltage dependence of activation to more depolarized potentials on DRG neurons, therefore, differs from the classic site 4 toxins that shift voltage dependence of activation in the opposite direction. In addition, JZTX-IV shows a slowing inactivation of sodium channel with a hyperpolarizing shift of the steady-state inactivation on acutely isolated rat cardiac cell and DRG neurons, differs from the classic site 3 toxins that do not affect the steady-state of inactivation. At high concentration, JZTX-IV has no significant effect on tetrodotoxin-resistant (TTX-R) sodium channels on rat DRG neurons and tetrodotoxin-sensitive (TTX-S) sodium channels on hippocampal neurons. Our data establish that, contrary to known toxins, JZTX-IV neither binds to the previously characterized classic site 4, nor site 3 by modifying channel gating, thus making it a novel probe of channel gating in sodium channels with potential to shed new light on this process.

  18. Communicating Under Channel Uncertainty

    CERN Document Server

    Warsi, Naqueeb; Shah, Tapan

    2010-01-01

    For a single transmit and receive antenna system, a new constellation design is proposed to combat errors in the phase estimate of the channel coefficient. The proposed constellation is a combination of PSK and PAM constellations, where PSK is used to provide protection against phase errors, while PAM is used to increase the transmission rate using the knowledge of the magnitude of the channel coefficient. The performance of the proposed constellation is shown to be significantly better than the widely used QAM in terms of probability of error. The proposed strategy can also be extended to systems using multiple transmit and receive antennas.

  19. Aspartame affects the electrical activity of projection neurons in central nervous system by inhibiting the calcium channel current in Drosophila%阿斯巴甜抑制钙通道电流影响果蝇中枢投射神经元电活动

    Institute of Scientific and Technical Information of China (English)

    王琦; 齐旻悦; 吴诗哲; 顾怀宇

    2016-01-01

    目的:从突触水平检验不同浓度的阿斯巴甜对果蝇中枢神经元影响及作用机制,为进一步探究阿斯巴甜生物安全性提供支持。方法采用膜片钳全细胞记录的方法,通过离子通道的阻断与分离,分别记录给药前后果蝇投射神经元(PN)的胆碱能突触微小兴奋性电流(mEPSC)、钙离子通道电流和钙通道瞬时电流密度,统计并分析mEPSC幅值和频率,以及钙通道电流峰值和瞬时电流密度。结果与给药前相比,8μg/ml阿斯巴甜会降低果蝇PN的mEPSC频率(t=22.05,P<0.01)、钙电流峰值(t=5.01,P<0.01)和瞬时电流密度(t=2.68,P<0.05);2μg/ml阿斯巴甜会降低果蝇PN的mEPSC频率(t=3.15,P<0.05),其他实验指标差异则无统计学意义(P>0.05)。结论一定浓度的阿斯巴甜可影响果蝇中枢投射神经元的电活动,并且该作用可能是通过影响钙电流而实现的。%Objective To study the effect of different concentrations of aspartame in Drosophila central nervous system , especially to the electrical activity of projection neuron (PN), and evaluate the biological security of aspartame and neural mechanism. Methods The whole-cell electrophysiological signals of projection neurons in Drosophila was detected by patch clamp. The recordings of mini excitatory postsynaptic currents (mEPSC) and calcium currents were performed in both pre-and post-of aspartame treatment. Results Aspartame treatments with 8 μg/ml could reduce the frequency of mEPSC (t=22.05, P0.05) at the same time. In addition, there have no statistically significant in aspartame treatments with 2μg/ml experimental groups except for the frequency of mEPSC (t=3.15, P<0.05). Conclusion There has a range of aspartame concentration can significantly affect the electrical activity of projection neurons in Drosophila central nervous system, which could be effective via the calcium

  20. Landfill Mining of Shredder Residues

    DEFF Research Database (Denmark)

    Hansen, Jette Bjerre; Hyks, Jiri; Shabeer Ahmed, Nassera

    In Denmark, shredder residues (SR) are classified as hazardous waste and until January 2012 the all SR were landfilled. It is estimated that more than 1.8 million tons of SR have been landfilled in mono cells. This paper describes investigations conducted at two Danish landfills. SR were excavated...

  1. Leaching From Biomass Gasification Residues

    DEFF Research Database (Denmark)

    Allegrini, Elisa; Boldrin, Alessio; Polletini, A.

    2011-01-01

    The aim of the present work is to attain an overall characterization of solid residues from biomass gasification. Besides the determination of chemical and physical properties, the work was focused on the study of leaching behaviour. Compliance and pH-dependence leaching tests coupled with geoche...

  2. An integrated assessment of the potential of agricultural and forestry residues for energy production in China

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ji [Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081 China; Zhang, Aiping [Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081 China; Lam, Shu Kee [Crop and Soil Sciences Section, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne, Melbourne Vic. 3010 Australia; Zhang, Xuesong [Joint Global Change Research Institute, Pacific Northwest National Laboratory and University of Maryland, College Park MD 20740 USA; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing MI 48824 USA; Thomson, Allison M. [Field to Market, The Alliance for Sustainable Agriculture, 777 N Capitol St. NE Suite 803 Washington DC 20002 USA; Lin, Erda [Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081 China; Jiang, Kejun [Energy Research Institute (ERI), Beijing 100038 China; Clarke, Leon E. [Joint Global Change Research Institute, Pacific Northwest National Laboratory and University of Maryland, College Park MD 20740 USA; Edmonds, James A. [Joint Global Change Research Institute, Pacific Northwest National Laboratory and University of Maryland, College Park MD 20740 USA; Kyle, Page G. [Joint Global Change Research Institute, Pacific Northwest National Laboratory and University of Maryland, College Park MD 20740 USA; Yu, Sha [Joint Global Change Research Institute, Pacific Northwest National Laboratory and University of Maryland, College Park MD 20740 USA; Zhou, Yuyu [Department of Geological & Atmospheric Sciences, Iowa State University, Ames IA 50011 USA; Zhou, Sheng [Institutes of Energy, Environment and Economy, Tsinghua University, Beijing 100084 China

    2016-01-05

    Biomass has been widely recognized as an important energy source with high potential to reduce greenhouse gas emissions while minimizing environmental pollution. In this study, we employ the Global Change Assessment Model to estimate the potential of agricultural and forestry residue biomass for energy production in China. Potential availability of residue biomass as an energy source was analyzed for the 21st century under different climate policy scenarios. Currently, the amount of total annual residue biomass, averaged over 2003-2007, is around 15519PJ in China, consisting of 10818PJ from agriculture residues (70%) and 4701PJ forestry residues (30%). We estimate that 12693PJ of the total biomass is available for energy production, with 66% derived from agricultural residue and 34% from forestry residue. Most of the available residue is from south central China (3347PJ), east China (2862PJ) and south-west China (2229PJ), which combined exceeds 66% of the total national biomass. Under the reference scenario without carbon tax, the potential availability of residue biomass for energy production is projected to be 3380PJ by 2050 and 4108PJ by 2095, respectively. When carbon tax is imposed, biomass availability increases substantially. For the CCS 450ppm scenario, availability of biomass increases to 9002PJ (2050) and 11524PJ (2095), respectively. For the 450ppm scenario without CCS, 9183 (2050) and 11150PJ (2095) residue biomass, respectively, is projected to be available. Moreover, the implementation of CCS will have a little impact on the supply of residue biomass after 2035. Our results suggest that residue biomass has the potential to be an important component in China's sustainable energy production portfolio. As a low carbon emission energy source, climate change policies that involve carbon tariff and CCS technology promote the use of residue biomass for energy production in a low carbon-constrained world.

  3. Central bank Financial Independence

    OpenAIRE

    J.Ramon Martinez-Resano

    2004-01-01

    Central bank independence is a multifaceted institutional design. The financial component has been seldom analysed. This paper intends to set a comprehensive conceptual background for central bank financial independence. Quite often central banks are modelled as robot like maximizers of some goal. This perspective neglects the fact that central bank functions are inevitably deployed on its balance sheet and have effects on its income statement. A financially independent central bank exhibits ...

  4. All channels open

    NARCIS (Netherlands)

    Frank Huysmans; Jos de Haan

    2010-01-01

    Original title: Alle kanalen staan open. The rapid changes taking place in the media landscape in the Netherlands - characterised by digitisation and convergence of media technologies - raise the question of how the Dutch are dealing with the many new opportunities that have opened up. All channels

  5. Chemistry in Microfluidic Channels

    Science.gov (United States)

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

    2011-01-01

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

  6. Ion Channels in Leukocytes

    Science.gov (United States)

    1991-07-01

    muscle k142), heart muscle (80), bo- are released. In recent years much has been learned vine pulmonar arter endothelial cells (251), and rat about the...channel analysbib of Lt. Potassium permeability in HeLa cancer BioL Chem. 265: 142416-141263, 1990. cells. evidence for a calcium-a’tivated potassium

  7. Ion channels in inflammation.

    Science.gov (United States)

    Eisenhut, Michael; Wallace, Helen

    2011-04-01

    Most physical illness in vertebrates involves inflammation. Inflammation causes disease by fluid shifts across cell membranes and cell layers, changes in muscle function and generation of pain. These disease processes can be explained by changes in numbers or function of ion channels. Changes in ion channels have been detected in diarrhoeal illnesses, pyelonephritis, allergy, acute lung injury and systemic inflammatory response syndromes involving septic shock. The key role played by changes in ion transport is directly evident in inflammation-induced pain. Expression or function of all major categories of ion channels like sodium, chloride, calcium, potassium, transient receptor potential, purinergic receptor and acid-sensing ion channels can be influenced by cyto- and chemokines, prostaglandins, leukotrienes, histamine, ATP, reactive oxygen species and protons released in inflammation. Key pathways in this interaction are cyclic nucleotide, phosphoinositide and mitogen-activated protein kinase-mediated signalling, direct modification by reactive oxygen species like nitric oxide, ATP or protons and disruption of the cytoskeleton. Therapeutic interventions to modulate the adverse and overlapping effects of the numerous different inflammatory mediators on each ion transport system need to target adversely affected ion transport systems directly and locally.

  8. Intermittency and exotic channels

    CERN Document Server

    Bialas, A

    1994-01-01

    It is pointed out that accurate measurements of short-range two-particle correlations in like-charge K\\pi and in \\pi^ 0\\pi^ 0 channels should be very helpful in determining the origin of the \\lq\\lq intermittency\\rq\\rq\\ phenomenon observed recently for the like-charge pion pairs.

  9. TRP channels: an overview

    DEFF Research Database (Denmark)

    Pedersen, Stine Falsig; Owsianik, Grzegorz; Nilius, Bernd

    2005-01-01

    to a plethora of data on the roles of TRPs in a variety of tissues and species, including mammals, insects, and yeast. The present review summarizes the most pertinent recent evidence regarding the structural and functional properties of TRP channels, focusing on the regulation and physiology of mammalian TRPs....

  10. Glutamate transporters combine transporter- and channel-like features

    NARCIS (Netherlands)

    Slotboom, DJ; Konings, WN; Lolkema, JS

    2001-01-01

    Glutamate transporters in the mammalian central nervous system have a unique position among secondary transport proteins as they exhibit glutamate-gated chloride-channel activity in addition to glutamate-transport activity. In this article, the available data on the structure of the glutamate transp

  11. TRP channels in microglia: role in physiology and disease

    Directory of Open Access Journals (Sweden)

    Yolima P Torres

    2015-02-01

    Full Text Available Microglia are responsible for modulating the cellular environment in the nervous system, where they have neuroprotective effects. In these cells has been reported the expression of different ion channels, including those belonging to the transient receptor potential (TRP family. TRP are nonselective cation channels that have six transmembrane domains and both N-terminus and C-terminus domain located in the cytoplasm. These proteins can be activated by mechanical, thermal and chemical stimuli as well as pH changes. Their activation can induce calcium influx contributing to regulate the intracellular calcium concentration. Different studies describe the effect of TRP channels in cellular processes such as osmotic regulation, cytokine production, proliferation, activation, cell death and responses to oxidative stress. As a result, these channels have an important role in neurodegenerative diseases, ischemia, inflammatory responses and pain perception. Modulating the activity of the TRP channels can be a therapeutic target for various diseases associated with the central nervous system. In this review the most relevant aspects about the role of the TRP channels in the physiology of microglia and their potential use as a therapeutic target in central nervous system diseases will be described.

  12. Identification of key residues involved in Si transport by the aquaglyceroporins.

    Science.gov (United States)

    Carpentier, Gabriel A; Garneau, Alexandre P; Marcoux, Andrée-Anne; Noël, Micheline; Frenette-Cotton, Rachelle; Isenring, Paul

    2016-09-01

    We recently demonstrated that the aquaglyceroporins (AQGPs) could act as potent transporters for orthosilicic acid (H4SiO4). Although interesting, this finding raised the question of whether water and H4SiO4, the transportable form of Si, permeate AQGPs by interacting with the same region of the pore, especially in view of the difference in molecular radius between the two substrates. Here, our goal was to identify residues that endow the AQGPs with the ability to facilitate Si diffusion by examining the transport characteristics of mutants in which residues were interchanged between a water-permeable but Si-impermeable channel (aquaporin 1 [AQP1]) and a Si-permeable but water-impermeable channel (AQP10). Our results indicate that the composition of the arginine filter (XX/R), known to include three residues that play an important role in water transport, may also be involved in Si selectivity. Interchanging the identities of the nonarginine residues within this filter causes Si transport to increase by approximately sevenfold in AQP1 and to decrease by approximately threefold in AQP10, whereas water transport and channel expression remain unaffected. Our results further indicate that two additional residues in the AQP arginine filter may be involved in substrate selectivity: replacing one of the residues has a profound effect on water permeability, and replacing the other has a profound effect on Si permeability. This study has thus led to the identification of residues that could play a key role in Si transport by the AQGPs and shown that substrate selectivity is likely ensured by more than one checkpoint within or near the pore.

  13. Beta-scorpion toxin effects suggest electrostatic interactions in domain II of voltage-dependent sodium channels. : Electrostatic interactions between segments IIS2, IIS3 and IIS4 of Na+ channel.

    OpenAIRE

    Mantegazza, Massimo; Cestèle, Sandrine

    2005-01-01

    International audience; Beta-scorpion toxins specifically modulate the voltage dependence of sodium channel activation by acting through a voltage-sensor trapping model. We used mutagenesis, functional analysis and the action of beta-toxin as tools to investigate the existence and role in channel activation of molecular interactions between the charged residues of the S2, S3 and S4 segments in domain II of sodium channels. Mutating to arginine the acidic residues of the S2 and S3 transmembran...

  14. Expression of transient receptor potential (TRP) channel mRNAs in the mouse olfactory bulb.

    Science.gov (United States)

    Dong, Hong-Wei; Davis, James C; Ding, ShengYuan; Nai, Qiang; Zhou, Fu-Ming; Ennis, Matthew

    2012-08-22

    Transient receptor potential (TRP) channels are a large family of cation channels. The 28 TRP channel subtypes in rodent are divided into 6 subfamilies: TRPC1-7, TRPV1-6, TRPM1-8, TRPP2/3/5, TRPML1-3 and TRPA1. TRP channels are involved in peripheral olfactory transduction. Several TRPC channels are expressed in unidentified neurons in the main olfactory bulb (OB), but the expression of most TRP channels in the OB has not been investigated. The present study employed RT-PCR as an initial survey of the expression of TRP channel mRNAs in the mouse OB and in 3 cell types: external tufted, mitral and granule cells. All TRP channel mRNAs except TRPV5 were detected in OB tissue. Single cell RT-PCR revealed that external tufted, mitral and granule cell populations expressed in aggregate 14 TRP channel mRNAs encompassing members of all 6 subfamilies. These different OB neuron populations expressed 7-12 channel mRNAs. Common channel expression was more similar among external tufted and mitral cells than among these cells and granule cells. These results indicate that a large number of TRP channel subtypes are expressed in OB neurons, providing the molecular bases for these channels to regulate OB neuron activity and central olfactory processing.

  15. A New Covert Channel over Cellular Voice Channel in Smartphones

    OpenAIRE

    Aloraini, Bushra; Johnson, Daryl; Stackpole, Bill; Mishra, Sumita

    2015-01-01

    Investigating network covert channels in smartphones has become increasingly important as smartphones have recently replaced the role of traditional computers. Smartphones are subject to traditional computer network covert channel techniques. Smartphones also introduce new sets of covert channel techniques as they add more capabilities and multiple network connections. This work presents a new network covert channel in smartphones. The research studies the ability to leak information from the...

  16. Design of a specific activator for skeletal muscle sodium channels uncovers channel architecture.

    Science.gov (United States)

    Cohen, Lior; Ilan, Nitza; Gur, Maya; Stühmer, Walter; Gordon, Dalia; Gurevitz, Michael

    2007-10-05

    Gating modifiers of voltage-gated sodium channels (Na(v)s) are important tools in neuroscience research and may have therapeutic potential in medicinal disorders. Analysis of the bioactive surface of the scorpion beta-toxin Css4 (from Centruroides suffusus suffusus) toward rat brain (rNa(v)1.2a) and skeletal muscle (rNa(v)1.4) channels using binding studies revealed commonality but also substantial differences, which were used to design a specific activator, Css4(F14A/E15A/E28R), of rNa(v)1.4 expressed in Xenopus oocytes. The therapeutic potential of Css4(F14A/E15A/E28R) was tested using an rNa(v)1.4 mutant carrying the same mutation present in the genetic disorder hypokalemic periodic paralysis. The activator restored the impaired gating properties of the mutant channel expressed in oocytes, thus offering a tentative new means for treatment of neuromuscular disorders with reduced muscle excitability. Mutant double cycle analysis employing toxin residues involved in the construction of Css4(F14A/E15A/E28R) and residues whose equivalents in the rat brain channel rNa(v)1.2a were shown to affect Css4 binding revealed significant coupling energy (>1.3 kcal/mol) between F14A and E592A at Domain-2/voltage sensor segments 1-2 (D2/S1-S2), R27Q and E1251N at D3/SS2-S6, and E28R with both E650A at D2/S3-S4 and E1251N at D3/SS2-S6. These results show that despite the differences in interactions with the rat brain and skeletal muscle Na(v)s, Css4 recognizes a similar region on both channel subtypes. Moreover, our data indicate that the S3-S4 loop of the voltage sensor module in Domain-2 is in very close proximity to the SS2-S6 segment of the pore module of Domain-3 in rNa(v)1.4. This is the first experimental evidence that the inter-domain spatial organization of mammalian Na(v)s resembles that of voltage-gated potassium channels.

  17. Characterization of two-pore channel 2 (TPCN2)-mediated Ca2+ currents in isolated lysosomes.

    Science.gov (United States)

    Schieder, Michael; Rötzer, Katrin; Brüggemann, Andrea; Biel, Martin; Wahl-Schott, Christian A

    2010-07-01

    Two-pore channels (TPCNs) have been proposed to form lysosomal Ca(2+) release channels that are activated by nicotinic acid adenine dinucleotide phosphate. Here, we employ a glass chip-based method to record for the first time nicotinic acid adenine dinucleotide phosphate -dependent currents through a two-pore channel (TPCN2) from intact lysosomes. We show that TPCN2 is a highly selective Ca(2+) channel that is regulated by intralysosomal pH. Using site-directed mutagenesis, we identify an amino acid residue in the putative pore region that is crucial for conferring high Ca(2+) selectivity. Our glass chip-based method will provide electrophysiological access not only to lysosomal TPCN channels but also to a broad range of other intracellular ion channels.

  18. Characterization of Two-pore Channel 2 (TPCN2)-mediated Ca2+ Currents in Isolated Lysosomes*

    Science.gov (United States)

    Schieder, Michael; Rötzer, Katrin; Brüggemann, Andrea; Biel, Martin; Wahl-Schott, Christian A.

    2010-01-01

    Two-pore channels (TPCNs) have been proposed to form lysosomal Ca2+ release channels that are activated by nicotinic acid adenine dinucleotide phosphate. Here, we employ a glass chip-based method to record for the first time nicotinic acid adenine dinucleotide phosphate -dependent currents through a two-pore channel (TPCN2) from intact lysosomes. We show that TPCN2 is a highly selective Ca2+ channel that is regulated by intralysosomal pH. Using site-directed mutagenesis, we identify an amino acid residue in the putative pore region that is crucial for conferring high Ca2+ selectivity. Our glass chip-based method will provide electrophysiological access not only to lysosomal TPCN channels but also to a broad range of other intracellular ion channels. PMID:20495006

  19. MOLEonline 2.0: interactive web-based analysis of biomacromolecular channels.

    Science.gov (United States)

    Berka, Karel; Hanák, Ondrej; Sehnal, David; Banás, Pavel; Navrátilová, Veronika; Jaiswal, Deepti; Ionescu, Crina-Maria; Svobodová Vareková, Radka; Koca, Jaroslav; Otyepka, Michal

    2012-07-01

    Biomolecular channels play important roles in many biological systems, e.g. enzymes, ribosomes and ion channels. This article introduces a web-based interactive MOLEonline 2.0 application for the analysis of access/egress paths to interior molecular voids. MOLEonline 2.0 enables platform-independent, easy-to-use and interactive analyses of (bio)macromolecular channels, tunnels and pores. Results are presented in a clear manner, making their interpretation easy. For each channel, MOLEonline displays a 3D graphical representation of the channel, its profile accompanied by a list of lining residues and also its basic physicochemical properties. The users can tune advanced parameters when performing a channel search to direct the search according to their needs. The MOLEonline 2.0 application is freely available via the Internet at http://ncbr.muni.cz/mole or http://mole.upol.cz.

  20. The Cauchy method of residues

    CERN Document Server

    Mitrinović, Dragoslav S

    1993-01-01

    Volume 1, i. e. the monograph The Cauchy Method of Residues - Theory and Applications published by D. Reidel Publishing Company in 1984 is the only book that covers all known applications of the calculus of residues. They range from the theory of equations, theory of numbers, matrix analysis, evaluation of real definite integrals, summation of finite and infinite series, expansions of functions into infinite series and products, ordinary and partial differential equations, mathematical and theoretical physics, to the calculus of finite differences and difference equations. The appearance of Volume 1 was acknowledged by the mathematical community. Favourable reviews and many private communications encouraged the authors to continue their work, the result being the present book, Volume 2, a sequel to Volume 1. We mention that Volume 1 is a revised, extended and updated translation of the book Cauchyjev raeun ostataka sa primenama published in Serbian by Nau~na knjiga, Belgrade in 1978, whereas the greater part ...

  1. Residual residential space as commons

    Directory of Open Access Journals (Sweden)

    Dan Rabinowitz

    2012-08-01

    Full Text Available Research on common pool resources (CPR, which began with a focus on rural communities and their defining agricultural practices, shifted recently also to the urban context, looking at community gardens, city parks and other recreational facilities. This article extends the use of CPR theory to residential complexes. Courtyards, lawns, lobbies, cellars, stairwells and other parts that fall outside individual apartments are aggregated as a new sub-set of CPR, defined herewith as Residual Residential Space (RRS. Based on findings from three main types of RRS in Israel, the article evaluates some of the mechanisms designed to regulate such space. In line with earlier work on CPR, the article suggests that legal instruments, important as they are for general guidance, do not suffice. To be effective they need to echo popular framings of Residual Residential Space, to be congruent with local sensibilities regarding micro-history, and to concur with expectations stake-holders might have from their own community.

  2. Tuning the ion selectivity of two-pore channels

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-01-17

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

  3. Microfluidic channel-assisted screening of hematopoietic malignancies.

    Science.gov (United States)

    Mughal, Farah; Baldock, Sara J; Karimiani, Ehsan Ghayoor; Telford, Nick; Goddard, Nicholas J; Day, Philip J R

    2014-03-01

    A simple microfluidic fluorescence in situ hybridization (FISH) device allowing accurate analysis of interphase nuclei in 1 hr in narrow channels is presented. Photolithography and fluorosilicic acid etching were used to fabricate microfluidic channels (referred to as FISHing lines) that allowed analysis of 10 samples on a glass microscope slide 0.2 µl of sample volume was used to fill a micro-channel, which resembled a 250-fold reduction compared to conventional FISH. FISH signals were comparable to conventional FISH, with 50-fold less probe consumption and 10-fold less time. Cells were immobilized in single file in channels just exceeding the diameter of the cells, and were used for minimal residual disease (MRD) analysis. To test the micro-channels for application in FISH, MRD was simulated by mixing K562 cells (an established chronic myeloid leukemia cell line) carrying the BCR/ABL fusion gene across 1:1 to 1:1,000 Jurkat cells (an established acute lymphoblastic leukemia cell line). The limit of detection was seen to be 1:100 cells and 1:1,000 cells for FISHing lines and conventional FISH, respectively; however, the conventional method seemed to over-score the presence of K562 cells. This may in part be attributed to FISHing lines practically eliminating the chance of duplicate screening of cells and hastened the time of screening, enhancing scoring of all cells within the channels. This was compared to 1 in 500 cells on the slide being analyzed with the conventional FISH.

  4. Electromechanical Apparatus Measures Residual Stress

    Science.gov (United States)

    Chern, Engmin J.; Flom, Yury

    1993-01-01

    Nondestructive test exploits relationship between stress and eddy-current-probe resistance. Yields data on residual stress or strain in metal tension/compression specimen (stress or strain remaining in specimen when no stress applied from without). Apparatus is assembly of commercial equipment: tension-or-compression testing machine, eddy-current probe, impedance gain-and-phase analyzer measuring impedance of probe coil, and desktop computer, which controls other equipment and processes data received from impedance gain-and-phase analyzer.

  5. Residual residential space as commons

    OpenAIRE

    2012-01-01

    Research on common pool resources (CPR), which began with a focus on rural communities and their defining agricultural practices, shifted recently also to the urban context, looking at community gardens, city parks and other recreational facilities. This article extends the use of CPR theory to residential complexes. Courtyards, lawns, lobbies, cellars, stairwells and other parts that fall outside individual apartments are aggregated as a new sub-set of CPR, defined herewith as Residual Resid...

  6. Sensing Task Allocation for Heterogeneous Channels in Cooperative Spectrum Sensing

    Directory of Open Access Journals (Sweden)

    Qihui Wu

    2010-12-01

    Full Text Available In the traditional centralized cooperative spectrum sensing, all secondary users sense the same channel. But, for a given channel, there exists detection performance diversity among all the users, due to the different signal-fading process. Involving the user with poor performance in cooperative sensing will not only deteriorate the detection correctness but also waste the sensing time. In the heterogeneous channels, the problem is even severe. A novel idea is to allocate the secondary users to sense different channels. We analyze the allocation problem before formulate it to be an optimization problem, which is a NP-hard problem. Then we propose the declined complexity algorithm in equal secondary user case and the two-hierarchy approach algorithm in unequal case. With the simulation, we verify the near optimality of the proposed algorithms and the advantage of the task allocation.

  7. Ion selectivity strategies of sodium channel selectivity filters.

    Science.gov (United States)

    Dudev, Todor; Lim, Carmay

    2014-12-16

    CONSPECTUS: Sodium ion channels selectively transport Na(+) cations across the cell membrane. These integral parts of the cell machinery are implicated in regulating the cardiac, skeletal and smooth muscle contraction, nerve impulses, salt and water homeostasis, as well as pain and taste perception. Their malfunction often results in various channelopathies of the heart, brain, skeletal muscles, and lung; thus, sodium channels are key drug targets for various disorders including cardiac arrhythmias, heart attack, stroke, migraine, epilepsy, pain, cancer, and autoimmune disorders. The ability of sodium channels to discriminate the native Na(+) among other competing ions in the surrounding fluids is crucial for proper cellular functions. The selectivity filter (SF), the narrowest part of the channel's open pore, lined with amino acid residues that specifically interact with the permeating ion, plays a major role in determining Na(+) selectivity. Different sodium channels have different SFs, which vary in the symmetry, number, charge, arrangement, and chemical type of the metal-ligating groups and pore size: epithelial/degenerin/acid-sensing ion channels have generally trimeric SFs lined with three conserved neutral serines and/or backbone carbonyls; eukaryotic sodium channels have EKEE, EEKE, DKEA, and DEKA SFs with an invariant positively charged lysine from the second or third domain; and bacterial voltage-gated sodium (Nav) channels exhibit symmetrical EEEE SFs, reminiscent of eukaryotic voltage-gated calcium channels. How do these different sodium channel SFs achieve high selectivity for Na(+) over its key rivals, K(+) and Ca(2+)? What factors govern the metal competition in these SFs and which of these factors are exploited to achieve Na(+) selectivity in the different sodium channel SFs? The free energies for replacing K(+) or Ca(2+) bound inside different model SFs with Na(+), evaluated by a combination of density functional theory and continuum dielectric

  8. Comprehensive utilization of digested residue

    Energy Technology Data Exchange (ETDEWEB)

    Reizhi Shen [Soil and Fertilizer Inst. of Shanghai Academy of Agricultural Sciences (China)

    2000-07-01

    The application history of biogas technology in China covers almost one century. Until the 1980's, people's attention not only focused on the benefit of biogas as people's daily fuel, but also on the comprehensive utilization of digested residues. People are more and more interested in these methods of comprehensive utilization, which has led to many research projects on, among others, ''digested effluent as feed additive for pigs'', ''digested sludge for growing mushroom'', and ''digested effluent as pesticide''. Not only are biogas fermentation, organic waste such as animal manure, crop straw, distillery wastewater and the wastewater from slaughter houses converted to biogas, but also digested residues are very useful with a lot of ''potential value'' and ''special functions'', which will bring far more benefits than biogas alone. Some progress on the comprehensive utilization of digested residues in the past ten years is summarized below. (orig.)

  9. Leptogenesis and residual CP symmetry

    CERN Document Server

    Chen, Peng; King, Stephen F

    2016-01-01

    We discuss flavour dependent leptogenesis in the framework of lepton flavour models based on discrete flavour and CP symmetries applied to the type-I seesaw model. Working in the flavour basis, we analyse the case of two general residual CP symmetries in the neutrino sector, which corresponds to all possible semi-direct models based on a preserved $Z_2$ in the neutrino sector, together with a CP symmetry, which constrains the PMNS matrix up to a single free parameter which may be fixed by the reactor angle. We systematically study and classify this case for all possible residual CP symmetries, and show that the $R$-matrix is tightly constrained up to a single free parameter, with only certain forms being consistent with successful leptogenesis, leading to possible connections between leptogenesis and PMNS parameters. The formalism is completely general in the sense that the two residual CP symmetries could result from any high energy discrete flavour theory which respects any CP symmetry. As a simple example,...

  10. 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.

  11. Activation of Slo2.1 channels by niflumic acid.

    Science.gov (United States)

    Dai, Li; Garg, Vivek; Sanguinetti, Michael C

    2010-03-01

    Slo2.1 channels conduct an outwardly rectifying K(+) current when activated by high [Na(+)](i). Here, we show that gating of these channels can also be activated by fenamates such as niflumic acid (NFA), even in the absence of intracellular Na(+). In Xenopus oocytes injected with <10 ng cRNA, heterologously expressed human Slo2.1 current was negligible, but rapidly activated by extracellular application of NFA (EC(50) = 2.1 mM) or flufenamic acid (EC(50) = 1.4 mM). Slo2.1 channels activated by 1 mM NFA exhibited weak voltage dependence. In high [K(+)](e), the conductance-voltage (G-V) relationship had a V(1/2) of +95 mV and an effective valence, z, of 0.48 e. Higher concentrations of NFA shifted V(1/2) to more negative potentials (EC(50) = 2.1 mM) and increased the minimum value of G/G(max) (EC(50) = 2.4 mM); at 6 mM NFA, Slo2.1 channel activation was voltage independent. In contrast, V(1/2) of the G-V relationship was shifted to more positive potentials when [K(+)](e) was elevated from 1 to 300 mM (EC(50) = 21.2 mM). The slope conductance measured at the reversal potential exhibited the same [K(+)](e) dependency (EC(50) = 23.5 mM). Conductance was also [Na(+)](e) dependent. Outward currents were reduced when Na(+) was replaced with choline or mannitol, but unaffected by substitution with Rb(+) or Li(+). Neutralization of charged residues in the S1-S4 domains did not appreciably alter the voltage dependence of Slo2.1 activation. Thus, the weak voltage dependence of Slo2.1 channel activation is independent of charged residues in the S1-S4 segments. In contrast, mutation of R190 located in the adjacent S4-S5 linker to a neutral (Ala or Gln) or acidic (Glu) residue induced constitutive channel activity that was reduced by high [K(+)](e). Collectively, these findings indicate that Slo2.1 channel gating is modulated by [K(+)](e) and [Na(+)](e), and that NFA uncouples channel activation from its modulation by transmembrane voltage and intracellular Na(+).

  12. Radar channel balancing with commutation

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

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

  13. CONTRIBUTIONS OF INTRACELLULAR IONS TO Kv CHANNEL VOLTAGE SENSOR DYNAMICS.

    Directory of Open Access Journals (Sweden)

    Samuel eGoodchild

    2012-06-01

    Full Text Available Voltage sensing domains of Kv channels control ionic conductance through coupling of the movement of charged residues in the S4 segment to conformational changes at the cytoplasmic region of the pore domain, that allow K+ ions to flow. Conformational transitions within the voltage sensing domain caused by changes in the applied voltage across the membrane field are coupled to the conducting pore region and the gating of ionic conductance. However, several other factors not directly linked to the voltage dependent movement of charged residues within the voltage sensor impact the dynamics of the voltage sensor, such as inactivation, ionic conductance, intracellular ion identity and block of the channel by intracellular ligands. The effect of intracellular ions on voltage sensor dynamics is of importance in the interpretation of gating current measurements and the physiology of pore/voltage sensor coupling. There is a significant amount of variability in the reported kinetics of voltage sensor deactivation kinetics of Kv channels attributed to different mechanisms such as open state stabilization, immobilization and relaxation processes of the voltage sensor. Here we separate these factors and focus on the causal role that intracellular ions can play in allosterically modulating the dynamics of Kv voltage sensor deactivation kinetics. These considerations are of critical importance in understanding the molecular determinants of the complete channel gating cycle from activation to deactivation.

  14. Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins

    Science.gov (United States)

    Peralta, Francisco Andrés; Huidobro-Toro, Juan Pablo

    2016-01-01

    Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel’s ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators. PMID:27384555

  15. Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins

    Directory of Open Access Journals (Sweden)

    Francisco Andrés Peralta

    2016-07-01

    Full Text Available Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel’s ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators.

  16. Geysering in boiling channels

    Energy Technology Data Exchange (ETDEWEB)

    Aritomi, Masanori; Takemoto, Takatoshi [Tokyo Institute of Technology, Tokyo (Japan); Chiang, Jing-Hsien [Japan NUS Corp. Ltd., Toyko (Japan)] [and others

    1995-09-01

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

  17. Lipid Ion Channels

    CERN Document Server

    Heimburg, Thomas

    2010-01-01

    The interpretation electrical phenomena in biomembranes is usually based on the assumption that the experimentally found discrete ion conduction events are due to a particular class of proteins called ion channels while the lipid membrane is considered being an inert electrical insulator. The particular protein structure is thought to be related to ion specificity, specific recognition of drugs by receptors and to macroscopic phenomena as nerve pulse propagation. However, lipid membranes in their chain melting regime are known to be highly permeable to ions, water and small molecules, and are therefore not always inert. In voltage-clamp experiments one finds quantized conduction events through protein-free membranes in their melting regime similar to or even undistinguishable from those attributed to proteins. This constitutes a conceptual problem for the interpretation of electrophysiological data obtained from biological membrane preparations. Here, we review the experimental evidence for lipid ion channels...

  18. ``Just Another Distribution Channel?''

    Science.gov (United States)

    Lemstra, Wolter; de Leeuw, Gerd-Jan; van de Kar, Els; Brand, Paul

    The telecommunications-centric business model of mobile operators is under attack due to technological convergence in the communication and content industries. This has resulted in a plethora of academic contributions on the design of new business models and service platform architectures. However, a discussion of the challenges that operators are facing in adopting these models is lacking. We assess these challenges by considering the mobile network as part of the value system of the content industry. We will argue that from the perspective of a content provider the mobile network is ‘just another’ distribution channel. Strategic options available for the mobile communication operators are to deliver an excellent distribution channel for content delivery or to move upwards in the value chain by becoming a content aggregator. To become a mobile content aggregator operators will have to develop or acquire complementary resources and capabilities. Whether this strategic option is sustainable remains open.

  19. Molecular Structure of the Human CFTR Ion Channel.

    Science.gov (United States)

    Liu, Fangyu; Zhang, Zhe; Csanády, László; Gadsby, David C; Chen, Jue

    2017-03-23

    The cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-binding cassette (ABC) transporter that uniquely functions as an ion channel. Here, we present a 3.9 Å structure of dephosphorylated human CFTR without nucleotides, determined by electron cryomicroscopy (cryo-EM). Close resemblance of this human CFTR structure to zebrafish CFTR under identical conditions reinforces its relevance for understanding CFTR function. The human CFTR structure reveals a previously unresolved helix belonging to the R domain docked inside the intracellular vestibule, precluding channel opening. By analyzing the sigmoid time course of CFTR current activation, we propose that PKA phosphorylation of the R domain is enabled by its infrequent spontaneous disengagement, which also explains residual ATPase and gating activity of dephosphorylated CFTR. From comparison with MRP1, a feature distinguishing CFTR from all other ABC transporters is the helix-loop transition in transmembrane helix 8, which likely forms the structural basis for CFTR's channel function.

  20. 2D IR spectroscopy reveals the role of water in the binding of channel-blocking drugs to the influenza M2 channel

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Ayanjeet, E-mail: ayanjeet@sas.upenn.edu, E-mail: gai@sas.upenn.edu; Gai, Feng, E-mail: ayanjeet@sas.upenn.edu, E-mail: gai@sas.upenn.edu; Hochstrasser, Robin M. [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Wang, Jun; DeGrado, William F. [Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California 94143 (United States); Moroz, Yurii S.; Korendovych, Ivan V. [Department of Chemistry, Syracuse University, Syracuse, New York 13244 (United States); Zanni, Martin [Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2014-06-21

    Water is an integral part of the homotetrameric M2 proton channel of the influenza A virus, which not only assists proton conduction but could also play an important role in stabilizing channel-blocking drugs. Herein, we employ two dimensional infrared (2D IR) spectroscopy and site-specific IR probes, i.e., the amide I bands arising from isotopically labeled Ala30 and Gly34 residues, to probe how binding of either rimantadine or 7,7-spiran amine affects the water dynamics inside the M2 channel. Our results show, at neutral pH where the channel is non-conducting, that drug binding leads to a significant increase in the mobility of the channel water. A similar trend is also observed at pH 5.0 although the difference becomes smaller. Taken together, these results indicate that the channel water facilitates drug binding by increasing its entropy. Furthermore, the 2D IR spectral signatures obtained for both probes under different conditions collectively support a binding mechanism whereby amantadine-like drugs dock in the channel with their ammonium moiety pointing toward the histidine residues and interacting with a nearby water cluster, as predicted by molecular dynamics simulations. We believe these findings have important implications for designing new anti-influenza drugs.

  1. DMT of weighted Parallel Channels: Application to Broadcast Channel

    CERN Document Server

    Mroueh, Lina; Othman, Ghaya Rekaya-Ben; Belfiore, Jean-Claude

    2008-01-01

    In a broadcast channel with random packet arrival and transmission queues, the stability of the system is achieved by maximizing a weighted sum rate capacity with suitable weights that depend on the queue size. The weighted sum rate capacity using Dirty Paper Coding (DPC) and Zero Forcing (ZF) is asymptotically equivalent to the weighted sum capacity over parallel single-channels. In this paper, we study the Diversity Multiplexing Tradeoff (DMT) of the fading broadcast channel under a fixed weighted sum rate capacity constraint. The DMT of both identical and different parallel weighted MISO channels is first derived. Finally, we deduce the DMT of a broadcast channel using DPC and ZF precoders.

  2. On partially entanglement breaking channels

    CERN Document Server

    Chruscinski, D; Chruscinski, Dariusz; Kossakowski, Andrzej

    2005-01-01

    Using well known duality between quantum maps and states of composite systems we introduce the notion of Schmidt number of a quantum channel. It enables one to define classes of quantum channels which partially break quantum entanglement. These classes generalize the well known class of entanglement breaking channels.

  3. Ion channeling revisited

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, Barney Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Corona, Aldo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nguyen, Anh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

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

  4. Residues involved in the pore-forming activity of the Clostridium perfringens iota toxin.

    Science.gov (United States)

    Knapp, Oliver; Maier, Elke; Waltenberger, Eva; Mazuet, Christelle; Benz, Roland; Popoff, Michel R

    2015-02-01

    Clostridium perfringens iota toxin is a binary toxin that is organized into enzyme (Ia) and binding (Ib) components. Ib forms channels in lipid bilayers and mediates the transport of Ia into the target cells. Here we show that Ib residues 334-359 contain a conserved pattern of alternating hydrophobic and hydrophilic residues forming two amphipathic β-strands involved in membrane insertion and channel formation. This stretch of amino acids shows remarkable structural and functional analogies with the β-pore-forming domain of C. perfringens epsilon toxin. Several mutations within the two amphipathic β-strands affected pore formation, single-channel conductance and ion selectivity (S339E-S341E, Q345H N346E) confirming their involvement in channel formation. F454 of Ib corresponds to the Φ-clamp F427 of anthrax protective antigen and F428 of C2II binary toxins. The mutation F454A resulted in a loss of cytotoxicity and strong increase in single-channel conductance (500 pS as compared with 85 pS in 1 M KCl) with a slight decrease in cation selectivity, indicating that the Φ-clamp is highly conserved and crucial for binary toxin activity. In contrast, the mutants Q367D, N430D, L443E had no or only minor effects on Ib properties, while T360I, T360A and T360W caused a dramatic effect on ion selectivity and single-channel conductance, indicating gross disturbance of the oligomer structure. This suggests that, at least in the iota toxin family, T360 has a structural role in the pore organization. Moreover, introduction of charged residues within the channel (S339E-S341E) or in the vestibule (Q367D, N430D and L443E) had virtually no effect on chloroquine or Ia binding, whereas F454A, T360I, T360A and T360W strongly decreased the chloroquine and Ia affinity to Ib. These results support that distinct residues within the vestibule interact with chloroquine and Ia or are responsible for channel structure, while the channel lining amino acids play a less important role.

  5. NIDDK Central Repository

    Data.gov (United States)

    U.S. Department of Health & Human Services — The NIDDK Central Repository stores biosamples, genetic and other data collected in designated NIDDK-funded clinical studies. The purpose of the NIDDK Central...

  6. Central Neuropathic Pain Syndromes.

    Science.gov (United States)

    Watson, James C; Sandroni, Paola

    2016-03-01

    Chronic pain is common in patients with neurologic complications of a central nervous system insult such as stroke. The pain is most commonly musculoskeletal or related to obligatory overuse of neurologically unaffected limbs. However, neuropathic pain can result directly from the central nervous system injury. Impaired sensory discrimination can make it challenging to differentiate central neuropathic pain from other pain types or spasticity. Central neuropathic pain may also begin months to years after the injury, further obscuring recognition of its association with a past neurologic injury. This review focuses on unique clinical features that help distinguish central neuropathic pain. The most common clinical central pain syndromes-central poststroke pain, multiple sclerosis-related pain, and spinal cord injury-related pain-are reviewed in detail. Recent progress in understanding of the pathogenesis of central neuropathic pain is reviewed, and pharmacological, surgical, and neuromodulatory treatments of this notoriously difficult to treat pain syndrome are discussed.

  7. Central venous catheter - flushing

    Science.gov (United States)

    ... during cancer treatment Bone marrow transplant - discharge Central venous catheter - dressing change Peripherally inserted central catheter - flushing Sterile technique Surgical wound care - open Review Date 9/22/2016 Updated by: ...

  8. Design and performance of the LANL 158-channel magnetoencephalography system

    Energy Technology Data Exchange (ETDEWEB)

    Matlachov, A. N. (Andrei N.); Kraus, Robert H., Jr.; Espy, M. A. (Michelle A.); Best, E. D. (Elaine D.); Briles, M. Carolyn; Raby, E. Y. (Eric Y.); Flynn, E. R.

    2002-01-01

    Design and performance for a recently completed whole-head magnetoencephalography (MEG) system using a superconducting imaging-surface (SIS) surrounding an array of SQUID magnetometers is reported. The helmet-like SIS is hemispherical in shape with a brim. The SIS images nearby sources while shields sensors from ambient magnetic noise. The shielding factor depends on magnetometer position and orientation. Typical shielding values of 200 in central sulcus area have been observed. Nine reference channels form three vector magnetometers, which are placed outside SIS. Signal channels consist of 149 SQUID magnetometers with 0.84nT/{Phi}{sub 0} field sensitivity and less then 3 fT/{radical}Hz noise. Typical SQUID - room temperature separations are about 20mm in the cooled state. Twelve 16-channel flux-lock loop units are connected to two 96-channel control units allowing up to 192 total SQUID channels. The control unit includes signal conditioning circuits as well as system test and control circuits. After conditioning all signals are fed to 192-channel, 24-bit data acquisition system capable of sampling up to 48kSa/sec/channel. The SIS-MEG system enables high-quality human functional brain data to be recorded in a one-layer magnetically shielded room.

  9. Polychlorinated Biphenyls (PCB) Residue Effects Database

    Data.gov (United States)

    U.S. Environmental Protection Agency — The PCB Residue Effects (PCBRes) Database was developed to assist scientists and risk assessors in correlating PCB and dioxin-like compound residues with toxic...

  10. Interpretation on Recycling Plastics from Shredder Residue

    Science.gov (United States)

    EPA is considering an interpretation of its regulations that would generally allow for recycling of plastic separated from shredder residue under the conditions described in the Voluntary Procedures for Recycling Plastics from Shredder Residue.

  11. Residual analysis for spatial point processes

    DEFF Research Database (Denmark)

    Baddeley, A.; Turner, R.; Møller, Jesper

    We define residuals for point process models fitted to spatial point pattern data, and propose diagnostic plots based on these residuals. The techniques apply to any Gibbs point process model, which may exhibit spatial heterogeneity, interpoint interaction and dependence on spatial covariates. Our...... residuals generalise the well-known residuals for point processes in time, used in signal processing and survival analysis. An important difference is that the conditional intensity or hazard rate of the temporal point process must be replaced by the Papangelou conditional intensity $lambda$ of the spatial...... process. Residuals are ascribed to locations in the empty background, as well as to data points of the point pattern. We obtain variance formulae, and study standardised residuals. There is also an analogy between our spatial residuals and the usual residuals for (non-spatial) generalised linear models...

  12. Evaluation of residue management practices effects on corn productivity, soil quality, and greenhouse gas emissions

    Science.gov (United States)

    Guzman, Jose German

    The removal of crop residues left after harvest is being considered as a potential feedstock source for bioethanol production which can contribute to the reduction of fossil fuel use and net greenhouse gas (GHG). The objectives of this study were to: (i) examine how tillage, N fertilization rates, residue removal, and their interactions affect crop productivity, (ii) SOC and soil physical properties, and (iii) GHG emissions, and (iv) calculated a soil C budget to determine how much crop residue can be sustainably be removed in Central and Southwest Iowa. After three years of residue removal under different management practices, the findings of this study suggest that a portion of the corn residue that is left on the soil surface after harvest can be removed, with no negative impacts in the short term continuous corn yield in sites at Central and Southwest Iowa. However, significant decreases in SOC sequestration rates, microbial biomass-C, bulk density, soil penetration resistance, wet aggregate stability, and infiltration rates were observed, but varied with soil type and management practices. Additionally, soil surface CO2 and N2O emissions were responsive to management practices; primarily by altering soil temperature, soil water content, soil mineral N, and crop growth. Results from soil C budget show that in 2010 when corn growth was not water stressed (lack of moisture), approximately 35 and 30% of the residue could be sustainably removed in the Central and Southwest sites, respectively. In 2011, drier soil conditions resulted in approximately 2 and 49% of the residue could be sustainably removed in the Central and Southwest sites, respectively.

  13. Residual Gas Fluorescence for Profile Measurements at the GSI UNILAC

    CERN Document Server

    Forck, P

    2002-01-01

    The high beam currents, delivered at the LINAC at GSI (UNILAC) can destroy intercepting diagnostics within one macro-pulse. As an alternative for a non-destructive profile measurement the methode for residual-gas-fluorescence is investigated. The fluorescence light is emitted by the N2 molecules of the residual gas at the blue wavelength range and can be monitored with a modern CCD-camera. The images are transferred via digital bus (IEEE 1394 'FireWire') and the profiles are generated by analysis of the images with a modern software tool (National Instruments 'LabView'). Due to the short beam pulses (about 0.2 ms) the light intensities emitted by the residual gas are low and require a high amplification (gain >106) which is realized with an image intensifier with double MCP (multi channel plate), connected with a fiber taper to the CCD-chip. The design parameters of the optics and electronics are discussed as well as the advantages of the digital data transmission. Measurements with heavy ion beams of several...

  14. Neutron residual stress measurements in linepipe

    Energy Technology Data Exchange (ETDEWEB)

    Law, Michael [ANTSO, PMB1 Menai, NSW, 2234 (Australia)]. E-mail: michael.law@ansto.gov.au; Gnaepel-Herold, Thomas [Department of Materials Science and Engineering, NCNR and University of Maryland (United States); Luzin, Vladimir [Department of Materials Science and Engineering, NCNR and University of Maryland (United States); Bowie, Graham [cNCNR and State University of New York at Stoneybrook (United States): Blue Scope Steel (Australia)

    2006-11-15

    Residual stresses in gas pipelines are generated by manufacturing and construction processes and may affect the subsequent pipe integrity. In the present work, the residual stresses in eight samples of linepipe were measured by neutron diffraction. Residual stresses changed with some coating processes. This has special implications in understanding and mitigating stress corrosion cracking, a major safety and economic problem in some gas pipelines.

  15. Residual stresses of thin, short rectangular plates

    Science.gov (United States)

    Andonian, A. T.; Danyluk, S.

    1985-01-01

    The analysis of the residual stresses in thin, short rectangular plates is presented. The analysis is used in conjunction with a shadow moire interferometry technique by which residual stresses are obtained over a large spatial area from a strain measurement. The technique and analysis are applied to a residual stress measurement of polycrystalline silicon sheet grown by the edge-defined film growth technique.

  16. 9 CFR 311.39 - Biological residues.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Biological residues. 311.39 Section... Biological residues. Carcasses, organs, or other parts of carcasses of livestock shall be condemned if it is determined that they are adulterated because of the presence of any biological residues....

  17. Cycling of grain legume residue nitrogen

    DEFF Research Database (Denmark)

    Jensen, E.S.

    1995-01-01

    Symbiotic nitrogen fixation by legumes is the main input of nitrogen in ecological agriculture. The cycling of N-15-labelled mature pea (Pisum sativum L.) residues was studied during three years in small field plots and lysimeters. The residual organic labelled N declined rapidly during the initial...... management methods in order to conserve grain legume residue N sources within the soil-plant system....

  18. 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.

  19. Electrostatics at the membrane define MscL channel mechanosensitivity and kinetics.

    Science.gov (United States)

    Zhong, Dalian; Blount, Paul

    2014-12-01

    The bacterial mechanosensitive channel of large conductance (MscL) serves as a biological emergency release valve, preventing the occurrence of cell lysis caused by acute osmotic stress. Its tractable nature allows it to serve as a paradigm for how a protein can directly sense membrane tension. Although much is known of the importance of the hydrophobicity of specific residues in channel gating, it has remained unclear whether electrostatics at the membrane plays any role. We studied MscL chimeras derived from functionally distinct orthologues: Escherichia coli and Staphylococcus aureus. Dissection of one set led to an observation that changing the charge of a single residue, K101, of E. coli (Ec)-MscL, effects a channel phenotype: when mutated to a negative residue, the channel is less mechanosensitive and has longer open dwell times. Assuming electrostatic interactions, we determined whether they are due to protein-protein or protein-lipid interactions by performing site-directed mutagenesis elsewhere in the protein and reconstituting channels into defined lipids, with and without negative head groups. We found that although both interactions appear to play some role, the primary determinant of the channel phenotype seems to be protein-lipid electrostatics. The data suggest a model for the role of electrostatic interactions in the dynamics of MscL gating.

  20. STIM1 activates CRAC channels through rotation of the pore helix to open a hydrophobic gate

    Science.gov (United States)

    Yamashita, Megumi; Yeung, Priscilla S.-W.; Ing, Christopher E.; McNally, Beth A.; Pomès, Régis; Prakriya, Murali

    2017-02-01

    Store-operated Ca2+ release-activated Ca2+ (CRAC) channels constitute a major pathway for Ca2+ influx and mediate many essential signalling functions in animal cells, yet how they open remains elusive. Here, we investigate the gating mechanism of the human CRAC channel Orai1 by its activator, stromal interacting molecule 1 (STIM1). We find that two rings of pore-lining residues, V102 and F99, work together to form a hydrophobic gate. Mutations of these residues to polar amino acids produce channels with leaky gates that conduct ions in the resting state. STIM1-mediated channel activation occurs through rotation of the pore helix, which displaces the F99 residues away from the pore axis to increase pore hydration, allowing ions to flow through the V102-F99 hydrophobic band. Pore helix rotation by STIM1 also explains the dynamic coupling between CRAC channel gating and ion selectivity. This hydrophobic gating mechanism has implications for CRAC channel function, pharmacology and disease-causing mutations.

  1. ROMK1 channel activity is regulated by monoubiquitination.

    Science.gov (United States)

    Lin, Dao-Hong; Sterling, Hyacinth; Wang, Zhijian; Babilonia, Elisa; Yang, Baofeng; Dong, Ke; Hebert, Steven C; Giebisch, Gerhard; Wang, Wen-Hui

    2005-03-22

    The ubiquitination of proteins can signal their degradation, modify their activity or target them to specific membranes or cellular organelles. Here, we show that monoubiquitination regulates the plasma membrane abundance and function of the potassium channel, ROMK. Immunoprecipitation of proteins obtained from renal cortex and outer medulla with ROMK antibody revealed that this channel was monoubiquitinated. To determine the ubiquitin binding site on ROMK1, all intracellular lysine (Lys) residues of ROMK1 were individually mutated to arginine (Arg), and a two-electrode voltage clamp was used to measure the ROMK1 channel activity in Xenopus oocytes. ROMK1 channel activity increased from 8.1 to 27.2 microA only when Lys-22 was mutated to Arg. Furthermore, Western blotting failed to detect the ubiquitinated ROMK1 in oocytes injected with R1K22R. Patch-clamp experiments showed that biophysical properties of R1K22R were identical to those of wild-type ROMK1. Although total protein expression levels of GFP-ROMK1 and GFP-R1K22R in oocytes were similar, confocal microscopy showed that the surface fluorescence intensity in oocytes injected with GFP-R1K22R was higher than that of GFP-ROMK1. In addition, biotin labeling of ROMK1 and R1K22R proteins expressed in HEK293 cells showed increased surface expression of the Lys-22 mutant channel. Finally, expression of R1K22R in COS7 cells significantly stimulated the surface expression of ROMK1. We conclude that ROMK1 can be monoubiquitinated and that Lys-22 is an ubiquitin-binding site. Thus, monoubiquitination of ROMK1 regulates channel activity by reducing the surface expression of channel protein. This finding implicates the linking of a single ubiquitin molecule to channels as an important posttranslational regulatory signal.

  2. Epithelial sodium channel modulates platelet collagen activation.

    Science.gov (United States)

    Cerecedo, Doris; Martínez-Vieyra, Ivette; Alonso-Rangel, Lea; Benítez-Cardoza, Claudia; Ortega, Arturo

    2014-03-01

    Activated platelets adhere to the exposed subendothelial extracellular matrix and undergo a rapid cytoskeletal rearrangement resulting in shape change and release of their intracellular dense and alpha granule contents to avoid hemorrhage. A central step in this process is the elevation of the intracellular Ca(2+) concentration through its release from intracellular stores and on throughout its influx from the extracellular space. The Epithelial sodium channel (ENaC) is a highly selective Na(+) channel involved in mechanosensation, nociception, fluid volume homeostasis, and control of arterial blood pressure. The present study describes the expression, distribution, and participation of ENaC in platelet migration and granule secretion using pharmacological inhibition with amiloride. Our biochemical and confocal analysis in suspended and adhered platelets suggests that ENaC is associated with Intermediate filaments (IF) and with Dystrophin-associated proteins (DAP) via α-syntrophin and β-dystroglycan. Migration assays, quantification of soluble P-selectin, and serotonin release suggest that ENaC is dispensable for migration and alpha and dense granule secretion, whereas Na(+) influx through this channel is fundamental for platelet collagen activation.

  3. Targeting ion channels in cystic fibrosis.

    Science.gov (United States)

    Mall, Marcus A; Galietta, Luis J V

    2015-09-01

    Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause a characteristic defect in epithelial ion transport that plays a central role in the pathogenesis of cystic fibrosis (CF). Hence, pharmacological correction of this ion transport defect by targeting of mutant CFTR, or alternative ion channels that may compensate for CFTR dysfunction, has long been considered as an attractive approach to a causal therapy of this life-limiting disease. The recent introduction of the CFTR potentiator ivacaftor into the therapy of a subgroup of patients with specific CFTR mutations was a major milestone and enormous stimulus for seeking effective ion transport modulators for all patients with CF. In this review, we discuss recent breakthroughs and setbacks with CFTR modulators designed to rescue mutant CFTR including the common mutation F508del. Further, we examine the alternative chloride channels TMEM16A and SLC26A9, as well as the epithelial sodium channel ENaC as alternative targets in CF lung disease, which remains the major cause of morbidity and mortality in patients with CF. Finally, we will focus on the hurdles that still need to be overcome to make effective ion transport modulation therapies available for all patients with CF irrespective of their CFTR genotype.

  4. Ion Channels in Neurological Disorders.

    Science.gov (United States)

    Kumar, Pravir; Kumar, Dhiraj; Jha, Saurabh Kumar; Jha, Niraj Kumar; Ambasta, Rashmi K

    2016-01-01

    The convergent endeavors of the neuroscientist to establish a link between clinical neurology, genetics, loss of function of an important protein, and channelopathies behind neurological disorders are quite intriguing. Growing evidence reveals the impact of ion channels dysfunctioning in neurodegenerative disorders (NDDs). Many neurological/neuromuscular disorders, viz, Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, amyotrophic lateral sclerosis, and age-related disorders are caused due to altered function or mutation in ion channels. To maintain cell homeostasis, ion channels are playing a crucial role which is a large transmembrane protein. Further, these channels are important as it determines the membrane potential and playing critically in the secretion of neurotransmitter. Behind NDDs, losses of pathological proteins and defective ion channels have been reported and are found to aggravate the disease symptoms. Moreover, ion channel dysfunctions are eliciting a range of symptoms, including memory loss, movement disabilities, neuromuscular sprains, and strokes. Since the possible mechanistic role played by aberrant ion channels, their receptor and associated factors in neurodegeneration remained elusive; therefore, it is a challenging task for the neuroscientist to implement the therapeutics for targeting NDDs. This chapter reviews the potential role of the ion channels in membrane physiology and brain homeostasis, where ion channels and their associated factors have been characterized with their functional consequences in neurological diseases. Moreover, mechanistic role of perturbed ion channels has been identified in various NDDs, and finally, ion channel modulators have been investigated for their therapeutic intervention in treating common NDDs.

  5. HCN Channels and Heart Rate

    Directory of Open Access Journals (Sweden)

    Ilaria Dentamaro

    2012-04-01

    Full Text Available Hyperpolarization and Cyclic Nucleotide (HCN -gated channels represent the molecular correlates of the “funny” pacemaker current (If, a current activated by hyperpolarization and considered able to influence the sinus node function in generating cardiac impulses. HCN channels are a family of six transmembrane domain, single pore-loop, hyperpolarization activated, non-selective cation channels. This channel family comprises four members: HCN1-4, but there is a general agreement to consider HCN4 as the main isoform able to control heart rate. This review aims to summarize advanced insights into the structure, function and cellular regulation of HCN channels in order to better understand the role of such channels in regulating heart rate and heart function in normal and pathological conditions. Therefore, we evaluated the possible therapeutic application of the selective HCN channels blockers in heart rate control.

  6. Natural radioactivity in petroleum residues

    Energy Technology Data Exchange (ETDEWEB)

    Gazineu, M.H.P. [UNICAP, Dept. de Quimica, Recife (Brazil); Gazineu, M.H.P.; Hazin, C.A. [UFPE, Dept. de Energia Nuclear, Recife (Brazil); Hazin, C.A. [Centro Regional de Ciencias Nucleares/ CNEN, Recife (Brazil)

    2006-07-01

    The oil extraction and production industry generates several types of solid and liquid wastes. Scales, sludge and water are typical residues that can be found in such facilities and that can be contaminated with Naturally Occurring Radioactive Material (N.O.R.M.). As a result of oil processing, the natural radionuclides can be concentrated in such residues, forming the so called Technologically Enhanced Naturally Occurring Radioactive Material, or T.E.N.O.R.M.. Most of the radionuclides that appear in oil and gas streams belong to the {sup 238}U and {sup 232}Th natural series, besides 40 K. The present work was developed to determine the radionuclide content of scales and sludge generated during oil extraction and production operations. Emphasis was given to the quantification of {sup 226}Ra, {sup 228}Ra and 40 K since these radionuclides,are responsible for most of the external exposure in such facilities. Samples were taken from the P.E.T.R.O.B.R.A.S. unity in the State of Sergipe, in Northeastern Brazil. They were collected directly from the inner surface of water pipes and storage tanks, or from barrels stored in the waste storage area of the E and P unit. The activity concentrations for {sup 226}Ra, {sup 228}Ra and 40 K were determined by using an HP Ge gamma spectrometric system. The results showed concentrations ranging from 42.7 to 2,110.0 kBq/kg for {sup 226}Ra, 40.5 to 1,550.0 kBq/kg for {sup 228}Ra, and 20.6 to 186.6 kBq/kg for 40 K. The results highlight the importance of determining the activity concentration of those radionuclides in oil residues before deciding whether they should be stored or discarded to the environment. (authors)

  7. Solow Residuals Without Capital Stocks

    DEFF Research Database (Denmark)

    Burda, Michael C.; Severgnini, Battista

    2014-01-01

    investment expenditures: one eliminates the capital stock by direct substitution, while the other employs generalized differences of detrended data and the Malmquist index. In short samples, these measures can exhibit consistently lower root mean squared errors than the Solow–Törnqvist counterpart. Capital......We use synthetic data generated by a prototypical stochastic growth model to assess the accuracy of the Solow residual (Solow, 1957) as a measure of total factor productivity (TFP) growth when the capital stock in use is measured with error. We propose two alternative measurements based on current...

  8. Heavy metals in surficial sediments of the central Bohai Sea:their distribution, speciation and sources

    Institute of Scientific and Technical Information of China (English)

    LIU Ming; FAN Dejiang; LIAO Yongjie; CHEN Bin; YANG Zuosheng

    2016-01-01

    The semi-enclosed Bohai Sea has received large amount of pollutants from surrounding rivers and sewage channels along the densely populated and industrializing Bohai coasts, as well as the offshore oil exploration in the sea. The concentrations of heavy metals copper, cobalt, nickel, zinc, lead, chromium and cadmium in 25 surface sediment samples from the central Bohai Sea are obtained by ICP-MS analysis. The speciation of these heavy metals is extracted and their distribution, fractionation, pollution status and sources are presented. High concentrations of copper, cobalt, nickel, zinc and chromium are found in the sediments off the coastal area of the Bohai Bay and the central Bohai Sea mud, while high concentrations of cadmium and lead are found in the sediments in the whole study area. The residual fraction is the dominant form of copper, cobalt, nickel, zinc and chromium in the surface sediments, while cadmium and lead have large proportions in the nonresidual fractions. The ecological risk assessment shows that the sediments in the study area are unpolluted with respect to the heavy metals of cobalt, nickel and chromium and unpolluted to moderately polluted with respect to copper, zinc, cadmium and lead. Cobalt, nickel and chromium mainly have natural origin and their concentrations significantly vary with the composition of the sediments. The contents of copper, zinc, lead and especially cadmium in sediments are suggested to be influenced by pollutants of human activities. The heavy metals in the surface sediments at most sampling stations are mainly come from the Huanghe River; the heavy metals in the sediments in the northernmost part of the study area are significantly affected by the sediment from the Luanhe River; while in the Bohai Bay and the central region they were affected by the sediment from the Haihe River and aerosol deposition.

  9. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  10. Residue depletion of albendazole and its metabolites in aquacultured yellow perch (Perca flavescens).

    Science.gov (United States)

    Yu, D; Evans, E R; Hasbrouck, N; Reimschuessel, R; Shaikh, B

    2012-12-01

    Metabolism and residue depletion studies are conducted to determine the marker residue (MR) of a drug in a target tissue of food animals. The MR is used to monitor potential unauthorized use of drugs. The current work is a continuation of our efforts to study metabolism and depletion profiles of albendazole in multiple finfish species to determine a common MR. The results of this study suggest that albendazole sulfone metabolite could potentially serve as MR for albendazole in yellow perch muscle, similar to channel catfish and hybrid striped bass as reported previously by us.

  11. Energy-Efficient Channel Handoff for Sensor Network-Assisted Cognitive Radio Network.

    Science.gov (United States)

    Usman, Muhammad; Khan, Muhammad Sajjad; Vu-Van, Hiep; Insoo, Koo

    2015-07-23

    The visiting and less-privileged status of the secondary users (SUs) in a cognitive radio network obligates them to release the occupied channel instantly when it is reclaimed by the primary user. The SU has a choice to make: either wait for the channel to become free, thus conserving energy at the expense of delayed transmission and delivery, or find and switch to a vacant channel, thereby avoiding delay in transmission at the expense of increased energy consumption. An energy-efficient decision that considers the tradeoff between energy consumption and continuous transmission needs to be taken as to whether to switch the channels. In this work, we consider a sensor network-assisted cognitive radio network and propose a backup channel, which is sensed by the SU in parallel with the operating channel that is being sensed by the sensor nodes. Imperfect channel sensing and residual energy of the SU are considered in order to develop an energy-efficient handoff strategy using the partially observable Markov decision process (POMDP), which considers beliefs about the operating and backup channels and the remaining energy of the SU in order to take an optimal channel handoff decision on the question "Should we switch the channel?" The objective is to dynamically decide in each time slot whether the SU should switch the channel or not in order to maximize throughput by utilizing energy efficiently. Extensive simulations were performed to show the effectiveness of the proposed channel handoff strategy, which was demonstrated in the form of throughput with respect to various parameters, i.e., detection probability, the channel idle probabilities of the operating and backup channels, and the maximum energy of the SU.

  12. A STUDY OF RESIDUAL STRENGTH OF SISAL TEXTILE REINFORCED VINYL ESTER

    Institute of Scientific and Technical Information of China (English)

    Li Yan

    2005-01-01

    In this study, the residual strength of sisal textile reinforced vinyl ester resin is studied using specimens with a central hole. Two kinds of chemicals, silane and permanganate, are used to treat sisal fibre surfaces. The effects of fibre surface treatments on the residual strength of sisal fibre reinforced composites with different central hole sizes are analysed. Optical microscopy (OM) surveys provide sound evidence for the relationship between residual strength properties and fracture morphologies of sisal textile reinforced vinyl ester.Several theoretical models used to predict the residual strength of laminated composites are briefly reviewed. Point stress criterion (PSC) and average stress criterion (ASC) models are used to analyze the mechanical properties of sisal textile reinforced polymers with a central hole in this research. Material constant, characteristic length (do or lc), is obtained and used to analyze the mechanical behavior of the composites. The residual strength of the composites predicted by PSC and ASC models is in good agreement with the experimental results..

  13. Understanding chlorophylls: central magnesium ion and phytyl as structural determinants.

    Science.gov (United States)

    Fiedor, Leszek; Kania, Agnieszka; Myśliwa-Kurdziel, Beata; Orzeł, Łukasz; Stochel, Grazyna

    2008-12-01

    Phytol, a C20 alcohol esterifying the C-17(3) propionate, and Mg2+ ion chelated in the central cavity, are conservative structural constituents of chlorophylls. To evaluate their intramolecular structural effects we prepared a series of metal- and phytyl-free derivatives of bacteriochlorophyll a and applied them as model chlorophylls. A detailed spectroscopic study on the model pigments reveals meaningful differences in the spectral characteristics of the phytylated and non-phytylated pigments. Their analysis in terms of solvatochromism and axial coordination shows how the central Mg and phytyl residue shape the properties of the pigment. Surprisingly, the presence/absence of the central Mg has no effect on the solvatochromism of (bacterio)chlorophyll pi-electron system and the hydrophobicity of phytyl does not interfere with the first solvation shell of the chromophore. However, both residues significantly influence the conformation of the pigment macrocycle and the removal of either residue increases the macrocycle flexibility. The chelation of Mg has a flattening effect on the macrocycle whereas bulky phytyl residue seems to control the conformation of the chromophore via steric interactions with ring V and its substituents. The analysis of spectroscopic properties of bacteriochlorophyllide (free acid) shows that esterification of the C-17(3) propionate is necessary in chlorophylls because the carboxyl group may act as a strong chelator of the central Mg. These observations imply that the truncated chlorophylls used in theoretical studies are not adequate as models of native chromophores, especially when fine effects are to be modeled.

  14. Functional interactions between residues in the S1, S4, and S5 domains of Kv2.1.

    Science.gov (United States)

    Bocksteins, E; Ottschytsch, N; Timmermans, J-P; Labro, A J; Snyders, D J

    2011-06-01

    The voltage-gated potassium channel subunit Kv2.1 forms heterotetrameric channels with the silent subunit Kv6.4. Chimeric Kv2.1 channels containing a single transmembrane segment from Kv6.4 have been shown to be functional. However, a Kv2.1 chimera containing both S1 and S5 from Kv6.4 was not functional. Back mutation of individual residues in this chimera (to the Kv2.1 counterpart) identified four positions that were critical for functionality: A200V and A203T in S1, and T343M and P347S in S5. To test for possible interactions in Kv2.1, we used substitutions with charged residues and tryptophan for the outermost pair 203/347. Combinations of substitutions with opposite charges at both T203 and S347 were tolerated but resulted in channels with altered gating kinetics, as did the combination of negatively charged aspartate substitutions. Double mutant cycle analysis with these mutants indicated that both residues are energetically coupled. In contrast, replacing both residues with a positively charged lysine together (T203K + S347K) was not tolerated and resulted in a folding or trafficking deficiency. The nonfunctionality of the T203K + S347K mutation could be restored by introducing the R300E mutation in the S4 segment of the voltage sensor. These results indicate that these specific S1, S4, and S5 residues are in close proximity and interact with each other in the functional channel, but are also important determinants for Kv2.1 channel maturation. These data support the view of an anchoring interaction between S1 and S5, but indicate that this interaction surface is more extensive than previously proposed.

  15. 3-manifold groups are virtually residually p

    CERN Document Server

    Aschenbrenner, Matthias

    2010-01-01

    Given a prime $p$, a group is called residually $p$ if the intersection of its $p$-power index normal subgroups is trivial. A group is called virtually residually $p$ if it has a finite index subgroup which is residually $p$. It is well-known that finitely generated linear groups over fields of characteristic zero are virtually residually $p$ for all but finitely many $p$. In particular, fundamental groups of hyperbolic $3$-manifolds are virtually residually $p$. It is also well-known that fundamental groups of $3$-manifolds are residually finite. In this paper we prove a common generalization of these results: every $3$-manifold group is virtually residually $p$ for all but finitely many~$p$. This gives evidence for the conjecture (Thurston) that fundamental groups of $3$-manifolds are linear groups.

  16. Spectral line polarimetry with a channeled polarimeter.

    Science.gov (United States)

    van Harten, Gerard; Snik, Frans; Rietjens, Jeroen H H; Martijn Smit, J; Keller, Christoph U

    2014-07-01

    Channeled spectropolarimetry or spectral polarization modulation is an accurate technique for measuring the continuum polarization in one shot with no moving parts. We show how a dual-beam implementation also enables spectral line polarimetry at the intrinsic resolution, as in a classic beam-splitting polarimeter. Recording redundant polarization information in the two spectrally modulated beams of a polarizing beam-splitter even provides the possibility to perform a postfacto differential transmission correction that improves the accuracy of the spectral line polarimetry. We perform an error analysis to compare the accuracy of spectral line polarimetry to continuum polarimetry, degraded by a residual dark signal and differential transmission, as well as to quantify the impact of the transmission correction. We demonstrate the new techniques with a blue sky polarization measurement around the oxygen A absorption band using the groundSPEX instrument, yielding a polarization in the deepest part of the band of 0.160±0.010, significantly different from the polarization in the continuum of 0.2284±0.0004. The presented methods are applicable to any dual-beam channeled polarimeter, including implementations for snapshot imaging polarimetry.

  17. Residual Fragments after Percutaneous Nephrolithotomy

    Directory of Open Access Journals (Sweden)

    Kaan Özdedeli

    2012-09-01

    Full Text Available Clinically insignificant residual fragments (CIRFs are described as asymptomatic, noninfectious and nonobstructive stone fragments (≤4 mm remaining in the urinary system after the last session of any intervention (ESWL, URS or PCNL for urinary stones. Their insignificance is questionable since CIRFs could eventually become significant, as their presence may result in recurrent stone growth and they may cause pain and infection due to urinary obstruction. They may become the source of persistent infections and a significant portion of the patients will have a stone-related event, requiring auxilliary interventions. CT seems to be the ultimate choice of assessment. Although there is no concensus about the timing, recent data suggests that it may be performed one month after the procedure. However, imaging can be done in the immediate postoperative period, if there are no tubes blurring the assessment. There is some evidence indicating that selective medical therapy may have an impact on decreasing stone formation rates. Retrograde intrarenal surgery, with its minimally invasive nature, seems to be the best way to deal with residual fragments.

  18. Residual number processing in dyscalculia.

    Science.gov (United States)

    Cappelletti, Marinella; Price, Cathy J

    2014-01-01

    Developmental dyscalculia - a congenital learning disability in understanding numerical concepts - is typically associated with parietal lobe abnormality. However, people with dyscalculia often retain some residual numerical abilities, reported in studies that otherwise focused on abnormalities in the dyscalculic brain. Here we took a different perspective by focusing on brain regions that support residual number processing in dyscalculia. All participants accurately performed semantic and categorical colour-decision tasks with numerical and non-numerical stimuli, with adults with dyscalculia performing slower than controls in the number semantic tasks only. Structural imaging showed less grey-matter volume in the right parietal cortex in people with dyscalculia relative to controls. Functional MRI showed that accurate number semantic judgements were maintained by parietal and inferior frontal activations that were common to adults with dyscalculia and controls, with higher activation for participants with dyscalculia than controls in the right superior frontal cortex and the left inferior frontal sulcus. Enhanced activation in these frontal areas was driven by people with dyscalculia who made faster rather than slower numerical decisions; however, activation could not be accounted for by response times per se, because it was greater for fast relative to slow dyscalculics but not greater for fast controls relative to slow dyscalculics. In conclusion, our results reveal two frontal brain regions that support efficient number processing in dyscalculia.

  19. Residual number processing in dyscalculia

    Directory of Open Access Journals (Sweden)

    Marinella Cappelletti

    2014-01-01

    Full Text Available Developmental dyscalculia – a congenital learning disability in understanding numerical concepts – is typically associated with parietal lobe abnormality. However, people with dyscalculia often retain some residual numerical abilities, reported in studies that otherwise focused on abnormalities in the dyscalculic brain. Here we took a different perspective by focusing on brain regions that support residual number processing in dyscalculia. All participants accurately performed semantic and categorical colour-decision tasks with numerical and non-numerical stimuli, with adults with dyscalculia performing slower than controls in the number semantic tasks only. Structural imaging showed less grey-matter volume in the right parietal cortex in people with dyscalculia relative to controls. Functional MRI showed that accurate number semantic judgements were maintained by parietal and inferior frontal activations that were common to adults with dyscalculia and controls, with higher activation for participants with dyscalculia than controls in the right superior frontal cortex and the left inferior frontal sulcus. Enhanced activation in these frontal areas was driven by people with dyscalculia who made faster rather than slower numerical decisions; however, activation could not be accounted for by response times per se, because it was greater for fast relative to slow dyscalculics but not greater for fast controls relative to slow dyscalculics. In conclusion, our results reveal two frontal brain regions that support efficient number processing in dyscalculia.

  20. From Toxins Targeting Ligand Gated Ion Channels to Therapeutic Molecules

    Directory of Open Access Journals (Sweden)

    Antoine Taly

    2011-03-01

    Full Text Available Ligand-gated ion channels (LGIC play a central role in inter-cellular communication. This key function has two consequences: (i these receptor channels are major targets for drug discovery because of their potential involvement in numerous human brain diseases; (ii they are often found to be the target of plant and animal toxins. Together this makes toxin/receptor interactions important to drug discovery projects. Therefore, toxins acting on LGIC are presented and their current/potential therapeutic uses highlighted.

  1. Ion Channels and Zinc: Mechanisms of Neurotoxicity and Neurodegeneration

    Directory of Open Access Journals (Sweden)

    Deborah R. Morris

    2012-01-01

    Full Text Available Ionotropic glutamate receptors, such as NMDA, AMPA and kainate receptors, are ligand-gated ion channels that mediate much of the excitatory neurotransmission in the brain. Not only do these receptors bind glutamate, but they are also regulated by and facilitate the postsynaptic uptake of the trace metal zinc. This paper discusses the role of the excitotoxic influx and accumulation of zinc, the mechanisms responsible for its cytotoxicity, and a number of disorders of the central nervous system that have been linked to these neuronal ion channels and zinc toxicity including ischemic brain injury, traumatic brain injury, and epilepsy.

  2. Acid-sensing ion channels contribute to neurotoxicity.

    Science.gov (United States)

    Chu, Xiang-Ping; Grasing, Kenneth A; Wang, John Q

    2014-02-01

    Acidosis that occurs under pathological conditions not only affects intracellular signaling molecules, but also directly activates a unique family of ligand-gated ion channels: acid-sensing ion channels (ASICs). ASICs are widely expressed throughout the central and peripheral nervous systems and play roles in pain sensation, learning and memory, and fear conditioning. Overactivation of ASICs contributes to neurodegenerative diseases such as ischemic brain/spinal cord injury, multiple sclerosis, Parkinson's disease, and Huntington's disease. Thus, targeting ASICs might be a potential therapeutic strategy for these conditions. This mini-review focuses on the electrophysiology and pharmacology of ASICs and roles of ASICs in neuronal toxicity.

  3. NMR analysis of interaction of LqhalphaIT scorpion toxin with a peptide corresponding to the D4/S3-S4 loop of insect para voltage-gated sodium channel.

    Science.gov (United States)

    Schnur, Einat; Turkov, Michael; Kahn, Roy; Gordon, Dalia; Gurevitz, Michael; Anglister, Jacob

    2008-01-22

    Voltage-gated sodium channels (Navs) are large transmembrane proteins that initiate action potential in electrically excitable cells. This central role in the nervous system has made them a primary target for a large number of neurotoxins. Scorpion alpha-neurotoxins bind to Navs with high affinity and slow their inactivation, causing a prolonged action potential. Despite the similarity in their mode of action and three-dimensional structure, alpha-toxins exhibit great variations in selectivity toward insect and mammalian Navs, suggesting differences in the binding surfaces of the toxins and the channels. The scorpion alpha-toxin binding site, termed neurotoxin receptor site 3, has been shown to involve the extracellular S3-S4 loop in domain 4 of the alpha-subunit of voltage-gated sodium channels (D4/S3-S4). In this study, the binding site for peptides corresponding to the D4/S3-S4 loop of the para insect Nav was mapped on the highly insecticidal alpha-neurotoxin, LqhalphaIT, from the scorpion Leiurus quinquestriatus hebraeus, by following changes in the toxin amide 1H and 15N chemical shifts upon binding. This analysis suggests that the five-residue turn (residues LqK8-LqC12) of LqhalphaIT and those residues in its vicinity interact with the D4/S3-S4 loop of Nav. Residues LqR18, LqW38, and LqA39 could also form a patch contributing to the interaction with D4/S3-S4. Moreover, a new bioactive residue, LqV13, was identified as being important for Nav binding and specifically for the interaction with the D4/S3-S4 loop. The contribution of LqV13 to NaV binding was further verified by mutagenesis. Future studies involving other extracellular regions of Navs are required for further characterization of the structure of the LqhalphaIT-Navs binding site.

  4. Mechanism of electromechanical coupling in voltage-gated potassium channels

    Directory of Open Access Journals (Sweden)

    Rikard eBlunck

    2012-09-01

    Full Text Available Voltage-gated ion channels play a central role in the generation of action potentials in the nervous system. They are selective for one type of ion – sodium, calcium or potassium. Voltage-gated ion channels are composed of a central pore that allows ions to pass through the membrane and four peripheral voltage sensing domains that respond to changes in the membrane potential. Upon depolarization, voltage sensors in voltage-gated potassium channels (Kv undergo conformational changes driven by positive charges in the S4 segment and aided by pairwise electrostatic interactions with the surrounding voltage sensor. Structure-function relations of Kv channels have been investigated in detail, and the resulting models on the movement of the voltage sensors now converge to a consensus; the S4 segment undergoes a combined movement of rotation, tilt and vertical displacement in order to bring 3-4 e+ each through the electric field focused in this region. Nevertheless, the mechanism by which the voltage sensor movement leads to pore opening, the electromechanical coupling, is still not fully understood. Thus, recently, electromechanical coupling in different Kv channels has been investigated with a multitude of techniques including electrophysiology, 3D crystal structures, fluorescence spectroscopy and molecular dynamics simulations. Evidently, the S4-S5 linker, the covalent link between the voltage sensor and pore, plays a crucial role. The linker transfers the energy from the voltage sensor movement to the pore domain via an interaction with the S6 C-termini, which are pulled open during gating. In addition, other contact regions have been proposed. This review aims to provide (i an in-depth comparison of the molecular mechanisms of electromechanical coupling in different Kv channels; (ii insight as to how the voltage sensor and pore domain influence one another; and (iii theoretical predictions on the movement of the cytosolic face of the KV channels

  5. Residual stress characteristics of gradation coating components. Keisha sosei coating buzai no zanryu oryoku tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Y.; Takahashi, M.; Miyazaki, M.; Kashiwaya, H. (Toshiba Corp. (Japan). Heavy Apparatus Engineering Lab.)

    1992-10-15

    Effect of the material characteristics and the coating layer thickness on residual stress was studied by using nondimensional thermal stress parameters. As for two layer composites, stress singularities at the edge of the interface of the direct bonding composites has decreased with the gradation composition. It is revealed that a residual stress, with bigger absolute value than two layer composites, has been working along the inner direction of the disk in gradation coating composite's layer surface. Dimensionless residual stress [delta], which works on the coating layer surface of the central part of gradation coating composite, has decreased with the increase of coating thickness ratio t/T(t; coating thickness, T; substrate thickness), and has been significant with the increase of Young's modulus ratio. The maximum residual stress that works on the coating surface in the central part of the gradation coating composite has been higher than the residual stress that works on the direct bonding surface of two layer composite. The dimensionless residual stress deformation in case of gradation coating composites has increased with the increase of coating thickness ratio and Young's modulus ratio. 7 refs., 12 figs.

  6. Channel Wall Landslides

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] The multiple landslides in this VIS image occur along a steep channel wall. Note the large impact crater in the context image. The formation of the crater may have initially weakened that area of the surface prior to channel formation. Image information: VIS instrument. Latitude -2.7, Longitude 324.8 East (35.2 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  7. Multiuser MIMO Channel Estimation

    Directory of Open Access Journals (Sweden)

    G.Indumathi

    2016-05-01

    Full Text Available In this paper, three beamforming design are considered for multi user MIMO system. First, transmit beamformers are fixed and the receive (RX beamformers are calculated. Transmit beamformer (TX-BFis projectedas a null space of appropriate channels. It reduces the interference for each user. Then the receiver beamformer is determined which maximize the SNR. This beamforming design provides less computation time. The second case is joint TX and RX beamformer for SNR maximization. In this transmitter and receiver beamformer are calculated using extended alternating optimization (EAO algorithm. The third one is joint transmitter and receiver beamforming for SNR and SINR maximization using EAO algorithm. This algorithm provides better error performance and sum rate performance. All the design cases are simulated by using standard multipath channel model. Our simulation results illustrate that compared to the least square design and zero forcing design, the joint TX and RX beamforming design using EAO algorithm provides faster beamforming and improved error performance and sum rate.

  8. Radical surgery in patients with residual disease after (chemo)radiation for cervical cancer

    NARCIS (Netherlands)

    Boers, Aniek; Arts, Henriette J. G.; Klip, Harry; Nijhuis, Esther R.; Pras, Elisabeth; Hollema, Harry; Wisman, G. Bea A.; Nijman, Hans W.; Mourits, Marian J. E.; Reyners, Anna K. L.; de Bock, Geertruida H.; Thomas, Gillian; van der Zee, Ate G. J.

    2014-01-01

    Objective: The aim of this study was to determine possible impact of routinely scheduled biopsies and more radical surgery for residual central disease in locally advanced cervical cancer after (chemo) radiation. Methods/Materials: Data were analyzed of a consecutive series of cervical cancer patien

  9. Cooperative transition between open and closed conformations in potassium channels.

    Directory of Open Access Journals (Sweden)

    Turkan Haliloglu

    Full Text Available Potassium (K+ ion channels switch between open and closed conformations. The nature of this important transition was revealed by comparing the X-ray crystal structures of the MthK channel from Methanobacterium thermoautotrophicum, obtained in its open conformation, and the KcsA channel from Streptomyces lividans, obtained in its closed conformation. We analyzed the dynamic characteristics and energetics of these homotetrameric structures in order to study the role of the intersubunit cooperativity in this transition. For this, elastic models and in silico alanine-scanning mutagenesis were used, respectively. Reassuringly, the calculations manifested motion from the open (closed towards the closed (open conformation. The calculations also revealed a network of dynamically and energetically coupled residues. Interestingly, the network suggests coupling between the selectivity filter and the gate, which are located at the two ends of the channel pore. Coupling between these two regions was not observed in calculations that were conducted with the monomer, which emphasizes the importance of the intersubunit interactions within the tetrameric structure for the cooperative gating behavior of the channel.

  10. Analysis of OFDM System using Pilot Channel Estimation

    Directory of Open Access Journals (Sweden)

    Amit

    2012-04-01

    Full Text Available Orthogonal Frequency Division Multiplexing (OFDM ismultiplexing technology of orthogonal multicarrier, and thechannel estimation model based on pilot in OFDM systemsis analyzed; Now that, the channel estimation based onpilot needs interpolation, in order to reduce the complexityof the interpolation algorithm, the FFT channel estimationalgorithm based on pilot is studied. Because of the directFFT channel estimation algorithm existing energy spectrumleakage problems, the optimized FFT channel estimationalgorithm based on the Hamming windowed function is putforward. A lot of conventional algorithms have tried tocancel the residual frame synchronization error (RFSE,which causes the performance degradation of channelestimation when using interpolation between pilot subcarriersin comb-type pilot-aided OFDM systems.Orthogonal frequency-division multiplexing (OFDM is atransmission technique that is based on many orthogonalcarriers that are transmitted simultaneously. Channelestimation techniques for OFDM systems, based on combtypepilot arrangement, over frequency-selective Rican andtime-varying fading channel are investigated. Theadvantage of comb-type pilot arrangement, in channelestimation, is the ability to track the variation in thechannel, which is the main reason for inter-carrierinterference modeled as an additive white Gaussian noise,leading to an increase in the noise level.

  11. A Micromechanical RF Channelizer

    Science.gov (United States)

    Akgul, Mehmet

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

  12. Role of hydrophobic and ionic forces in the movement of S4 of the Shaker potassium channel.

    Science.gov (United States)

    Elliott, David J S; Neale, Edward J; Munsey, Tim S; Bannister, John P; Sivaprasadarao, Asipu

    2012-12-01

    Voltage-gated ion (K(+), Na(+), Ca(2+)) channels contain a pore domain (PD) surrounded by four voltage sensing domains (VSD). Each VSD is made up of four transmembrane helices, S1-S4. S4 contains 6-7 positively charged residues (arginine/lysine) separated two hydrophobic residues, whereas S1-S3 contribute to two negatively charged clusters. These structures are conserved among all members of the voltage-gated ion channel family and play essential roles in voltage gating. The role of S4 charged residues in voltage gating is well established: During depolarization, they move out of the membrane electric field, exerting a mechanical force on channel gates, causing them to open. However, the role of the intervening hydrophobic residues in voltage sensing is unclear. Here we studied the role of these residues in the prototypical Shaker potassium channel. We have altered the physicochemical properties of both charged and hydrophobic positions of S4 and examined the effect of these modifications on the gating properties of the channel. For this, we have introduced cysteines at each of these positions, expressed the mutants in Xenopus oocytes, and examined the effect of in situ addition of charge, via Cd(2+), on channel gating by two-electrode voltage clamp. Our results reveal a face of the S4 helix (comprising residues L358, L361, R365 and R368) where introduction of charge at hydrophobic positions destabilises the closed state and removal of charges from charged positions has an opposite effect. We propose that hydrophobic residues play a crucial role in limiting gating to a physiological voltage range.

  13. Carbenoxolone inhibits Pannexin1 channels through interactions in the first extracellular loop.

    Science.gov (United States)

    Michalski, Kevin; Kawate, Toshimitsu

    2016-02-01

    Pannexin1 (Panx1) is an ATP release channel important for controlling immune responses and synaptic strength. Various stimuli including C-terminal cleavage, a high concentration of extracellular potassium, and voltage have been demonstrated to activate Panx1. However, it remains unclear how Panx1 senses and integrates such diverse stimuli to form an open channel. To provide a clue on the mechanism underlying Panx1 channel gating, we investigated the action mechanism of carbenoxolone (CBX), the most commonly used small molecule for attenuating Panx1 function triggered by a wide range of stimuli. Using a chimeric approach, we discovered that CBX reverses its action polarity and potentiates the voltage-gated channel activity of Panx1 when W74 in the first extracellular loop is mutated to a nonaromatic residue. A systematic mutagenesis study revealed that conserved residues in this loop also play important roles in CBX function, potentially by mediating CBX binding. We extended our experiments to other Panx1 inhibitors such as probenecid and ATP, which also potentiate the voltage-gated channel activity of a Panx1 mutant at position 74. Notably, probenecid alone can activate this mutant at a resting membrane potential. These data suggest that CBX and other inhibitors, including probenecid, attenuate Panx1 channel activity through modulation of the first extracellular loop. Our experiments are the first step toward identifying a previously unknown mode of CBX action, which provide insight into the role of the first extracellular loop in Panx1 channel gating.

  14. Ion channels-related diseases.

    Science.gov (United States)

    Dworakowska, B; Dołowy, K

    2000-01-01

    There are many diseases related to ion channels. Mutations in muscle voltage-gated sodium, potassium, calcium and chloride channels, and acetylcholine-gated channel may lead to such physiological disorders as hyper- and hypokalemic periodic paralysis, myotonias, long QT syndrome, Brugada syndrome, malignant hyperthermia and myasthenia. Neuronal disorders, e.g., epilepsy, episodic ataxia, familial hemiplegic migraine, Lambert-Eaton myasthenic syndrome, Alzheimer's disease, Parkinson's disease, schizophrenia, hyperekplexia may result from dysfunction of voltage-gated sodium, potassium and calcium channels, or acetylcholine- and glycine-gated channels. Some kidney disorders, e.g., Bartter's syndrome, policystic kidney disease and Dent's disease, secretion disorders, e.g., hyperinsulinemic hypoglycemia of infancy and cystic fibrosis, vision disorders, e.g., congenital stationary night blindness and total colour-blindness may also be linked to mutations in ion channels.

  15. Unifying Theories of Mobile Channels

    Directory of Open Access Journals (Sweden)

    Gerard Ekembe Ngondi

    2016-06-01

    Full Text Available In this paper we present the denotational semantics for channel mobility in the Unifying Theories of Programming (UTP semantics framework. The basis for the model is the UTP theory of reactive processes (precisely, the UTP semantics for Communicating Sequential Processes (CSP, which is slightly extended to allow the mobility of channels: the set of actions in which a process is authorised to participate, originally static or constant (set during the process's definition, is now made dynamic or variable: it can change during the process's execution. A channel is thus moved around by communicating it via other channels and then allowing the receiving process to extend its alphabet with the received channel. New healthiness conditions are stated to ensure an appropriate use of mobile channels.

  16. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  17. Effect of Residue Mutation on the Electrostatic Potential in EcCIC

    Institute of Scientific and Technical Information of China (English)

    ZOU Xianwu; DONG Shuxiang; WANG Xiaoqing; HUANG Shengyou

    2007-01-01

    The effect of mutation of strongly conserved porelining residues in the chloride channel EcClC on the electrostatic potential and binding free energy of the chloride ion was studied using explicit protein-membrane structures. Electrostatic potential distribution and binding free energy of the chloride ion at different binding sites in the wild-type and mutated EcClC were calculated with APBS. The potential data reveal that the electrostatic potential around the selectivity filter, especially around the site Sext and Scen becomes more negative as the residue R147 was mutated to C147. The electrostatic binding free energy shows that the binding free energy of the chloride ion at all binding sites becomes more positive as R147 was mutated. It follows that mutation of R147 decreases ion stabilization at binding sites and affects channel's gating.

  18. Modeling of the Binding of Peptide Blockers to Voltage-Gated Potassium Channels: Approaches and Evidence.

    Science.gov (United States)

    Novoseletsky, V N; Volyntseva, A D; Shaitan, K V; Kirpichnikov, M P; Feofanov, A V

    2016-01-01

    Modeling of the structure of voltage-gated potassium (KV) channels bound to peptide blockers aims to identify the key amino acid residues dictating affinity and provide insights into the toxin-channel interface. Computational approaches open up possibilities for in silico rational design of selective blockers, new molecular tools to study the cellular distribution and functional roles of potassium channels. It is anticipated that optimized blockers will advance the development of drugs that reduce over activation of potassium channels and attenuate the associated malfunction. Starting with an overview of the recent advances in computational simulation strategies to predict the bound state orientations of peptide pore blockers relative to KV-channels, we go on to review algorithms for the analysis of intermolecular interactions, and then take a look at the results of their application.

  19. Computer simulation of ion channel gating: the M(2) channel of influenza A virus in a lipid bilayer

    Science.gov (United States)

    Schweighofer, K. J.; Pohorille, A.

    2000-01-01

    The transmembrane fragment of the influenza virus M(2) protein forms a homotetrameric channel that transports protons. In this paper, we use molecular dynamics simulations to help elucidate the mechanism of channel gating by four histidines that occlude the channel lumen in the closed state. We test two competing hypotheses. In the "shuttle" mechanism, the delta nitrogen atom on the extracellular side of one histidine is protonated by the incoming proton, and, subsequently, the proton on the epsilon nitrogen atom is released on the opposite side. In the "water-wire" mechanism, the gate opens because of electrostatic repulsion between four simultaneously biprotonated histidines. This allows for proton transport along the water wire that penetrates the gate. For each system, composed of the channel embedded in a hydrated phospholipid bilayer, a 1.3-ns trajectory was obtained. It is found that the states involved in the shuttle mechanism, which contain either single-protonated histidines or a mixture of single-protonated histidines plus one biprotonated residue, are stable during the simulations. Furthermore, the orientations and dynamics of water molecules near the gate are conducive to proton transfer. In contrast, the fully biprotonated state is not stable. Additional simulations show that if only two histidines are biprotonated, the channel deforms but the gate remains closed. These results support the shuttle mechanism but not the gate-opening mechanism of proton gating in M(2).

  20. Basic residues within the ebolavirus VP35 protein are required for its viral polymerase cofactor function.

    Science.gov (United States)

    Prins, Kathleen C; Binning, Jennifer M; Shabman, Reed S; Leung, Daisy W; Amarasinghe, Gaya K; Basler, Christopher F

    2010-10-01

    The ebolavirus (EBOV) VP35 protein binds to double-stranded RNA (dsRNA), inhibits host alpha/beta interferon (IFN-α/β) production, and is an essential component of the viral polymerase complex. Structural studies of the VP35 C-terminal IFN inhibitory domain (IID) identified specific structural features, including a central basic patch and a hydrophobic pocket, that are important for dsRNA binding and IFN inhibition. Several other conserved basic residues bordering the central basic patch and a separate cluster of basic residues, called the first basic patch, were also identified. Functional analysis of alanine substitution mutants indicates that basic residues outside the central basic patch are not required for dsRNA binding or for IFN inhibition. However, minigenome assays, which assess viral RNA polymerase complex function, identified these other basic residues to be critical for viral RNA synthesis. Of these, a subset located within the first basic patch is important for VP35-nucleoprotein (NP) interaction, as evidenced by the inability of alanine substitution mutants to coimmunoprecipitate with NP. Therefore, first basic patch residues are likely critical for replication complex formation through interactions with NP. Coimmunoprecipitation studies further demonstrate that the VP35 IID is sufficient to interact with NP and that dsRNA can modulate VP35 IID interactions with NP. Other basic residue mutations that disrupt the VP35 polymerase cofactor function do not affect interaction with NP or with the amino terminus of the viral polymerase. Collectively, these results highlight the importance of conserved basic residues from the EBOV VP35 C-terminal IID and validate the VP35 IID as a potential therapeutic target.

  1. MORTAR WITH UNSERVICEABLE TIRE RESIDUES

    Directory of Open Access Journals (Sweden)

    José Aparecido Canova

    2009-12-01

    Full Text Available This study analyzes the effects of unserviceable tire residues on rendering mortar using lime and washed sand at a volumetric proportion of 1:6. The ripened composite was dried in an oven and combined with both cement at a volumetric proportion of 1:1.5:9 and rubber powder in proportional aggregate volumes of 6, 8, 10, and 12%. Water exudation was evaluated in the plastic state. Water absorption by capillarity, fresh shrinkage and mass loss, restrained shrinkage and mass loss, void content, flexural strength, and deformation energy under compression were evaluated in the hardened state. There was an improvement in the water exudation and water absorption by capillarity and drying shrinkage, as well as a reduction of the void content and flexural strength. The product studied significantly aided the water exudation from mortar and, capillary elevation in rendering.

  2. MORTAR WITH UNSERVICEABLE TIRE RESIDUES

    Directory of Open Access Journals (Sweden)

    J. A. Canova

    2009-01-01

    Full Text Available This study analyzes the effects of unserviceable tire residues on rendering mortar using lime and washed sand at a volumetric proportion of 1:6. The ripened composite was dried in an oven and combined with both cement at a volumetric proportion of 1:1.5:9 and rubber powder in proportional aggregate volumes of 6, 8, 10, and 12%. Water exudation was evaluated in the plastic state. Water absorption by capillarity, fresh shrinkage and mass loss, restrained shrinkage and mass loss, void content, flexural strength, and deformation energy under compression were evaluated in the hardened state. There was an improvement in the water exudation and water absorption by capillarity and drying shrinkage, as well as a reduction of the void content and flexural strength. The product studied significantly aided the water exudation from mortar and, capillary elevation in rendering.

  3. Residual Liquefaction under Standing Waves

    DEFF Research Database (Denmark)

    Kirca, V.S. Ozgur; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    This paper summarizes the results of an experimental study which deals with the residual liquefaction of seabed under standing waves. It is shown that the seabed liquefaction under standing waves, although qualitatively similar, exhibits features different from that caused by progressive waves....... The experimental results show that the buildup of pore-water pressure and the resulting liquefaction first starts at the nodal section and spreads towards the antinodal section. The number of waves to cause liquefaction at the nodal section appears to be equal to that experienced in progressive waves for the same...... wave height. Recommendations are made as to how to assess liquefaction potential in standing waves. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE)....

  4. Forest residues in cattle feed

    Directory of Open Access Journals (Sweden)

    João Elzeário Castelo Branco Iapichini

    2012-12-01

    Full Text Available The ruminants are capable of converting low-quality food, when they are complementes with high-energy source. Through the use of regional agricultural residues is possible to conduct more economical production systems, since energetic foods have high cost in animal production. There is very abundant availability of residues in agroforestry activities worldwide, so that if a small fraction of them were used with appropriate technical criteria they could largely meet the needs of existing herds in the world and thus meet the demands of consumption of protein of animal origin. The Southwest Region of São Paulo State has large area occupied by reforestation and wide availability of non-timber forest residues, which may represent more concentrated energetic food for ruminant production. This experiment aimed to evaluate the acceptability of ground pine (20, 30 and 40%, replacing part of the energetic food (corn, present in the composition of the concentrate and was performed at the Experimental Station of Itapetininga - Forest Institute / SMA, in the dry season of 2011. It were used four crossbred steers, mean 18 months old, average body weight of 250 kg, housed in a paddock provided with water ad libitum and covered troughs for supplementation with the experimental diet. The adjustment period of the animals was of 07 days and the measurement of the levels of consumption, physiological changes, acceptability and physiological parameters were observed during the following 25 days. The concentrate supplement was formulated based on corn (76.2%, Soybean Meal (20%, urea (2%, Ammonium sulfate (0.4%, calcite (1.4%, Mineral Core (1% and finely ground Pine Cone, replacing corn. In preparing food, the formulas were prepared to make them isoproteic/energetic, containing the following nutrient levels: 22% Crude Protein (CP and 79% of Total Nutrients (TDN. The animals received the supplement in three steps for each level of cone replaced, being offered in the

  5. Central Laboratories Services

    Data.gov (United States)

    Federal Laboratory Consortium — The TVA Central Laboratories Services is a comprehensive technical support center, offering you a complete range of scientific, engineering, and technical services....

  6. Geometric pumping in autophoretic channels

    CERN Document Server

    Michelin, Sebastien; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric

    2015-01-01

    Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.

  7. Genetic Control of Potassium Channels.

    Science.gov (United States)

    Amin, Ahmad S; Wilde, Arthur A M

    2016-06-01

    Approximately 80 genes in the human genome code for pore-forming subunits of potassium (K(+)) channels. Rare variants (mutations) in K(+) channel-encoding genes may cause heritable arrhythmia syndromes. Not all rare variants in K(+) channel-encoding genes are necessarily disease-causing mutations. Common variants in K(+) channel-encoding genes are increasingly recognized as modifiers of phenotype in heritable arrhythmia syndromes and in the general population. Although difficult, distinguishing pathogenic variants from benign variants is of utmost importance to avoid false designations of genetic variants as disease-causing mutations.

  8. Capacities of quantum amplifier channels

    Science.gov (United States)

    Qi, Haoyu; Wilde, Mark M.

    2017-01-01

    Quantum amplifier channels are at the core of several physical processes. Not only do they model the optical process of spontaneous parametric down-conversion, but the transformation corresponding to an amplifier channel also describes the physics of the dynamical Casimir effect in superconducting circuits, the Unruh effect, and Hawking radiation. Here we study the communication capabilities of quantum amplifier channels. Invoking a recently established minimum output-entropy theorem for single-mode phase-insensitive Gaussian channels, we determine capacities of quantum-limited amplifier channels in three different scenarios. First, we establish the capacities of quantum-limited amplifier channels for one of the most general communication tasks, characterized by the trade-off between classical communication, quantum communication, and entanglement generation or consumption. Second, we establish capacities of quantum-limited amplifier channels for the trade-off between public classical communication, private classical communication, and secret key generation. Third, we determine the capacity region for a broadcast channel induced by the quantum-limited amplifier channel, and we also show that a fully quantum strategy outperforms those achieved by classical coherent-detection strategies. In all three scenarios, we find that the capacities significantly outperform communication rates achieved with a naive time-sharing strategy.

  9. Demystifying Mechanosensitive Piezo Ion Channels.

    Science.gov (United States)

    Xu, X Z Shawn

    2016-06-01

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

  10. T-type channels become highly permeable to sodium ions using an alternative extracellular turret region (S5-P) outside the selectivity filter.

    Science.gov (United States)

    Senatore, Adriano; Guan, Wendy; Boone, Adrienne N; Spafford, J David

    2014-04-25

    T-type (Cav3) channels are categorized as calcium channels, but invertebrate ones can be highly sodium-selective channels. We illustrate that the snail LCav3 T-type channel becomes highly sodium-permeable through exon splicing of an extracellular turret and descending helix in domain II of the four-domain Cav3 channel. Highly sodium-permeable T-type channels are generated without altering the invariant ring of charged residues in the selectivity filter that governs calcium selectivity in calcium channels. The highly sodium-permeant T-type channel expresses in the brain and is the only splice isoform expressed in the snail heart. This unique splicing of turret residues offers T-type channels a capacity to serve as a pacemaking sodium current in the primitive heart and brain in lieu of Nav1-type sodium channels and to substitute for voltage-gated sodium channels lacking in many invertebrates. T-type channels would also contribute substantially to sodium leak conductances at rest in invertebrates because of their large window currents.

  11. Proton-lambda correlation functions at the LHC with account for residual correlations

    CERN Document Server

    Shapoval, V M; Naboka, V Yu

    2015-01-01

    The theoretical analysis of $\\bar{p}-\\Lambda \\oplus p-\\bar{\\Lambda}$ correlation function in 10% most central Au+Au collisions at RHIC energy $\\sqrt{s_{NN}}=200$ GeV shows that the contribution of residual correlations is the necessary factor to obtain a satisfactory description of the experimental data. A neglecting of the residual correlation effect, leads to unrealistically low source radius, about 2 times smaller than the corresponding value for $p-\\Lambda \\oplus \\bar{p}-\\bar{\\Lambda}$ case, when one fits the experimental correlation function within Lednicky-Lyuboshitz analytical model. Recently an approach accounting effectively for residual correlations for the baryon-antibaryon correlation function was proposed, and a good RHIC data description was reached with the source radius extracted from the hydrokinetic model (HKM). The $\\bar{p}-\\Lambda$ scattering length, as well as the parameters characterizing the residual correlation effect --- annihilation dip amplitude and its inverse width --- were extrac...

  12. Beyond the Manual Channel

    DEFF Research Database (Denmark)

    , the main focus there is on spoken languages in their written and spoken forms. This series of workshops, however, offers a forum for researchers focussing on sign languages. For the fourth time, the workshop had sign language corpora as its main topic. This time, the focus was on any aspect beyond......This collection of papers stems from the Sixth Workshop on the Representation and Processing of Sign Languages, held in May 2014 as a satellite to the Language Resources and Evaluation Conference in Reykjavik. While there has been occasional attention for sign languages at the main LREC conference...... the manual channel. Not surprisingly, most papers deal with non-manuals on the face. Once again, the papers at this workshop clearly identify the potentials of even closer cooperation between sign linguists and sign language engineers, and we think it is events like this that contribute a lot to a better...

  13. SEACAB qualification with Frascati Neutron Generator residual dose measurements

    Energy Technology Data Exchange (ETDEWEB)

    Töre, Candan, E-mail: c.tore@seaingenieria.es; Ortego, Pedro; Rodriguez, Alain

    2015-10-15

    Highlights: • We developed a new R2S residual dose methodology SEACAB for TBM shield design. • Combines MCNPX mesh tally and ACAB to compute activation in a fast and simple way. • We qualified SEACAB by comparison with second campaign of FNG “duct experiment”. • Calculated dose and flux compare very well with TUD measurements at 7 decay times. • Presently SEACAB is being used in the calculation of residual dose at ITER port 16. - Abstract: The European fusion technology programme considers two test blanket modules, both helium-cooled, one with lithium ceramic pebbles and beryllium and other with Pb–Li eutectic alloy. The high level of neutron flux required for tritium breeding and the neutron multiplication properties of Be and Pb imply the need for a large neutron attenuation in the associated shielding to meet the shutdown dose requirements. A new SEACAB methodology has been developed to apply the rigorous two-step method with the use of the mesh tally of MCNPX and activation code ACAB and it has been qualified with the results of the 2nd campaign of the “duct-experiment” performed with Frascati Neutron Generator in a block of steel and moderator layers with a central cavity where the residual photon flux and dose were measured.

  14. Channel Floor Yardangs

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] Released 19 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth. Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms. The yardangs in this image are forming in channel floor deposits. The channel itself is funneling the wind to cause the erosion. Image information: VIS instrument. Latitude 4.5, Longitude 229.7 East (133.3 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from

  15. Preservation of meandering river channels in uniformly aggrading channel belts

    NARCIS (Netherlands)

    van de Lageweg, W.I.; Schuurman, F.; Cohen, K.M.; van Dijk, W. M.; Shimizu, Y.; Kleinhans, M.G.

    2016-01-01

    Channel belt deposits from meandering river systems commonly display an internal architecture of stacked depositional features with scoured basal contacts due to channel and bedform migration across a range of scales. Recognition and correct interpretation of these bounding surfaces is essential to

  16. Designing a C84 fullerene as a specific voltage-gated sodium channel blocker

    Science.gov (United States)

    Hilder, Tamsyn A.; Chung, Shin-Ho

    2013-07-01

    Fullerene derivatives demonstrate considerable potential for numerous biological applications, such as the effective inhibition of HIV protease. Recently, they were identified for their ability to indiscriminately block biological ion channels. A fullerene derivative which specifically blocks a particular ion channel could lead to a new set of drug leads for the treatment of various ion channel-related diseases. Here, we demonstrate their extraordinary potential by designing a fullerene which mimics some of the functions of μ-conotoxin, a peptide derived from cone snail venom which potently binds to the bacterial voltage-gated sodium channel (NavAb). We show, using molecular dynamics simulations, that the C84 fullerene with six lysine derivatives uniformly attached to its surface is selective to NavAb over a voltage-gated potassium channel (Kv1.3). The side chain of one of the lysine residues protrudes into the selectivity filter of the channel, while the methionine residues located just outside of the channel form hydrophobic contacts with the carbon atoms of the fullerene. The modified C84 fullerene strongly binds to the NavAb channel with an affinity of 46 nM but binds weakly to Kv1.3 with an affinity of 3 mM. This potent blocker of NavAb may serve as a structural template from which potent compounds can be designed for the targeting of mammalian Nav channels. There is a genuine need to target mammalian Nav channels as a form of treatment of various diseases which have been linked to their malfunction, such as epilepsy and chronic pain.

  17. Neuroprotective role of ATP-sensitive potassium channels in cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    Hong-shuo SUN; Zhong-ping FENG

    2013-01-01

    ATP-sensitive potassium (KATP) channels are weak,inward rectifiers that couple metabolic status to cell membrane electrical activity,thus modulating many cellular functions.An increase in the ADP/ATP ratio opens KATP channels,leading to membrane hyperpolarization.KATP channels are ubiquitously expressed in neurons located in different regions of the brain,including the hippocampus and cortex.Brief hypoxia triggers membrane hyperpolarization in these central neurons.In vivo animal studies confirmed that knocking out the Kir6.2 subunit of the KATP channels increases ischemic infarction,and overexpression of the Kir6.2 subunit reduces neuronal injury from ischemic insults.These findings provide the basis for a practical strategy whereby activation of endogenous KATP channels reduces cellular damage resulting from cerebral ischemic stroke.KATP channel modulators may prove to be clinically useful as part of a combination therapy for stroke management in the future.

  18. Decreasing residual aluminum level in drinking water

    Institute of Scientific and Technical Information of China (English)

    王志红; 崔福义

    2004-01-01

    The relativity of coagulant dosage, residual turbidity, temperature, pH etc. with residual aluminum concentration were investigated, and several important conclusions were achieved. Firstly, dosage of alum-coagulant or PAC1 influences residual aluminum concentration greatly. There is an optimal-dosage-to-aluminum, a bit less than the optimal-dosage-to-turbidity. Secondly, it proposes that decreasing residual aluminum concentration can be theoretically divided into two methods, either decreasing (even removing) the concentration of particulate aluminum component, or decreasing dissolved aluminum. In these tests there is an optimal value of residual turbidity of postprecipitation at 7.0 NTU. Thirdly, residual aluminum level will increase while water temperature goes higher. At the last, optimal pH value corresponds a minimum dissolved aluminum at a given turbidity. Data shows the optimal pH value decreases with water temperature's increasing.

  19. Detection of antibiotic residues in poultry meat.

    Science.gov (United States)

    Sajid, Abdul; Kashif, Natasha; Kifayat, Nasira; Ahmad, Shabeer

    2016-09-01

    The antibiotic residues in poultry meat can pose certain hazards to human health among them are sensitivity to antibiotics, allergic reactions, mutation in cells, imbalance of intestinal micro biota and bacterial resistance to antibiotics. The purpose of the present paper was to detect antibiotic residue in poultry meat. During the present study a total of 80 poultry kidney and liver samples were collected and tested for detection of different antibiotic residues at different pH levels Eschericha coli at pH 6, 7 and Staphyloccocus aureus at pH 8 & 9. Out of 80 samples only 4 samples were positive for antibiotic residues. The highest concentrations of antibiotic residue found in these tissues were tetracycline (8%) followed by ampicilin (4%), streptomycine (2%) and aminoglycosides (1%) as compared to other antibiotics like sulfonamides, neomycine and gentamycine. It was concluded that these microorganism at these pH levels could be effectively used for detection of antibiotic residues in poultry meat.

  20. The First Extracellular Domain Plays an Important Role in Unitary Channel Conductance of Cx50 Gap Junction Channels.

    Directory of Open Access Journals (Sweden)

    Xiaoling Tong

    Full Text Available Gap junction (GJ channels provide direct passage for ions and small molecules to be exchanged between neighbouring cells and are crucial for many physiological processes. GJ channels can be gated by transjunctional voltage (known as Vj-gating and display a wide range of unitary channel conductance (γj, yet the domains responsible for Vj-gating and γj are not fully clear. The first extracellular domain (E1 of several connexins has been shown to line part of their GJ channel pore and play important roles in Vj-gating properties and/or ion permeation selectivity. To test roles of the E1 of Cx50 GJ channels, we generated a chimera, Cx50Cx36E1, where the E1 domain of Cx50 was replaced with that of Cx36, a connexin showing quite distinct Vj-gating and γj from those of Cx50. Detailed characterizations of the chimera and three point mutants in E1 revealed that, although the E1 domain is important in determining γj, the E1 domain of Cx36 is able to effectively function within the context of the Cx50 channel with minor changes in Vj-gating properties, indicating that sequence differences between the E1 domains in Cx36 and Cx50 cannot account for their drastic differences in Vj-gating and γj. Our homology models of the chimera and the E1 mutants revealed that electrostatic properties of the pore-lining residues and their contribution to the electric field in the pore are important factors for the rate of ion permeation of Cx50 and possibly other GJ channels.

  1. CHANNEL ESTIMATION FOR ITERATIVE DECODING OVER FADING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    K. H. Sayhood; Wu Lenan

    2002-01-01

    A method of coherent detection and channel estimation for punctured convolutional coded binary Quadrature Amplitude Modulation (QAM) signals transmitted over a frequency-flat Rayleigh fading channels used for a digital radio broadcasting transmission is presented. Some known symbols are inserted in the encoded data stream to enhance the channel estimation process.The pilot symbols are used to replace the existing parity symbols so no bandwidth expansion is required. An iterative algorithm that uses decoding information as well as the information contained in the known symbols is used to improve the channel parameter estimate. The scheme complexity grows exponentially with the channel estimation filter length. The performance of the system is compared for a normalized fading rate with both perfect coherent detection (corresponding to a perfect knowledge of the fading process and noise variance) and differential detection of Differential Amplitude Phase Shift Keying (DAPSK). The tradeoff between simplicity of implementation and bit-error-rate performance of different techniques is also compared.

  2. Mirrored serpentine flow channels for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Rock, Jeffrey Allan (Rochester, NY)

    2000-08-08

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

  3. Littoral steering of deltaic channels

    Science.gov (United States)

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

    2016-11-01

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

  4. Effects of Ultrasonic Treatment on Residue Properties

    Institute of Scientific and Technical Information of China (English)

    Sun Yudong; Zhang Qiang; Shi Honghong; Wang Xue; Liu Bo

    2013-01-01

    The changes in properties and structural parameters of four vacuum residue samples before and after ultrasonic treatment were analyzed. Ultrasonic treatment could increase the carbon residue value, decrease the average molecular weight and viscosity, which can barely inlfuence the density of vacuum residue. Meanwhile the constitution of residue can be varied including the decrease in the content of saturates, aromatics and asphaltenes, while the increase in the content of resins can lead to an increase in the total content of asphaltenes and resins. Among the four kinds of residue samples, there is a common trend that the more the content of asphaltenes in feedstock is, the more the increase in the content of resins, the more signiifcant decrease in the aromatic content and the less decrease in the saturates content after ultrasonic treatment of residue would be. Changes in the structure and content of asphaltenes caused by ultrasonic treatment have a signiifcant impact on the changes in residue properties. Ultrasonic treatment has changed the structural parameters of residue such as decrease in the total carbon number of average molecule (CTotal), the total number of rings (RT), the aromatic carbon number (CA),the aromatic rings number (RA) and the naphthenic rings number (RN) , and increase of characterization factor (KH). The study has indicated that ultrasonic treatment of vacuum residue can change the average structure of residue, and the changes in the content and structure of asphaltenes are the main cause leading to property changes. The results of residue hydrotreat-ing revealed that coke yield decreased, whereas the gas and light oil yield and conversion increased after ultrasonic treat-ment of vacuum residue.

  5. Studies Of Residual Flexibility And Vibration Testing

    Science.gov (United States)

    Admire, John R.; Tinker, Michael L.; Bookout, Paul S.; Ivey, Edward W.

    1995-01-01

    Collection of reports presents theoretical and experimental studies in which concept of residual flexibility applied to modal vibration testing and verification of mathematical models of vibrations of flexible structure constrained by another structure. "Residual flexibility" denotes that part of interface flexibility due to mode shapes out of frequency range of test. Studies directed toward assessing residual-flexibility approach as substitute for fixed-base vibrational testing of payloads installed in spacecraft.

  6. Biochemical suitability of crop residues for cellulosic ethanol: disincentives to nitrogen fertilization in corn agriculture.

    Science.gov (United States)

    Gallagher, Morgan E; Hockaday, William C; Masiello, Caroline A; Snapp, Sieglinde; McSwiney, Claire P; Baldock, Jeffrey A

    2011-03-01

    Concerns about energy security and climate change have increased biofuel demand, particularly ethanol produced from cellulosic feedstocks (e.g., food crop residues). A central challenge to cropping for cellulosic ethanol is the potential environmental damage from increased fertilizer use. Previous analyses have assumed that cropping for carbohydrate in residue will require the same amount of fertilizer as cropping for grain. Using (13)C nuclear magnetic resonance, we show that increases in biomass in response to fertilization are not uniform across biochemical classes (carbohydrate, protein, lipid, lignin) or tissues (leaf and stem, grain, reproductive support). Although corn grain responds vigorously and nonlinearly, corn residue shows only modest increases in carbohydrate yields in response to high levels of fertilization (25% increase with 202 kg N ha(-1)). Lignin yields in the residue increased almost twice as much as carbohydrate yields in response to nitrogen, implying that residue feedstock quality declines as more fertilizer is applied. Fertilization also increases the decomposability of corn residue, implying that soil carbon sequestration becomes less efficient with increased fertilizer. Our results suggest that even when corn is grown for grain, benefits of fertilization decline rapidly after the ecosystem's N demands are met. Heavy application of fertilizer yields minimal grain benefits and almost no benefits in residue carbohydrates, while degrading the cellulosic ethanol feedstock quality and soil carbon sequestration capacity.

  7. Central Pain Syndrome

    Science.gov (United States)

    ... or hands. Central pain syndrome often begins shortly after the causative injury or damage, but may be delayed by months or even years, especially if it is related to post-stroke pain. × Definition Central pain syndrome is a neurological ...

  8. Central centrifugal cicatricial alopecia

    Directory of Open Access Journals (Sweden)

    Collin Blattner

    2013-01-01

    Full Text Available Central centrifugal cicatricial alopecia is a common cause of progressive permanent apical alopecia. This unique form of alopecia includes entities previously know as "hot comb alopecia," "follicular degeneration syndrome," "pseudopelade" in African Americans and "central elliptical pseudopelade" in Caucasians. The etiology appears to be multifactorial and the condition occurs in all races.

  9. Optimal central bank transparency

    NARCIS (Netherlands)

    van der Cruijsen, C.A.B.; Eijffinger, S.C.W.; Hoogduin, L.

    2008-01-01

    Should central banks increase their degree of transparency any further? We show that there is likely to be an optimal intermediate degree of central bank transparency. Up to this optimum more transparency is desirable: it improves the quality of private sector inflation forecasts. But beyond the opt

  10. Optimal central bank transparency

    NARCIS (Netherlands)

    van der Cruijsen, C.A.B.; Eijffinger, S.C.W.; Hoogduin, L.H.

    2010-01-01

    Should central banks increase their degree of transparency any further? We show that there is likely to be an optimal intermediate degree of central bank transparency. Up to this optimum more transparency is desirable: it improves the quality of private sector inflation forecasts. But beyond the opt

  11. VLSI binary multiplier using residue number systems

    Energy Technology Data Exchange (ETDEWEB)

    Barsi, F.; Di Cola, A.

    1982-01-01

    The idea of performing multiplication of n-bit binary numbers using a hardware based on residue number systems is considered. This paper develops the design of a VLSI chip deriving area and time upper bounds of a n-bit multiplier. To perform multiplication using residue arithmetic, numbers are converted from binary to residue representation and, after residue multiplication, the result is reconverted to the original notation. It is shown that the proposed design requires an area a=o(n/sup 2/ log n) and an execution time t=o(log/sup 2/n). 7 references.

  12. Modeling of Residual Stresses In Toughened Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2006-01-01

    -depth knowledge of the residual stresses in toughened glass near holes and edges where the total stress state is a combination of contact stresses and residual stresses. The present paper, presenting the derivation and results for a model predicting the residual stresses in a glass plate far from edges and holes......, is a step towards such a model. The model is based on the Instant Freeze concept with a few modifications. Current work, using a partial differential equation approach for the modeling and state-of-the-art in modeling residual stresses in glass is briefly presented, and a short description of the toughening...

  13. Residual models for nonlinear partial differential equations

    Directory of Open Access Journals (Sweden)

    Garry Pantelis

    2005-11-01

    Full Text Available Residual terms that appear in nonlinear PDEs that are constructed to generate filtered representations of the variables of the fully resolved system are examined by way of a consistency condition. It is shown that certain commonly used empirical gradient models for the residuals fail the test of consistency and therefore cannot be validated as approximations in any reliable sense. An alternate method is presented for computing the residuals. These residual models are independent of free or artificial parameters and there direct link with the functional form of the system of PDEs which describe the fully resolved system are established.

  14. Structure and Mechanism of a Pentameric Formate Channel

    Energy Technology Data Exchange (ETDEWEB)

    Waight, A.; Love, J; Wang, D

    2010-01-01

    Formate transport across the inner membrane is a critical step in anaerobic bacterial respiration. Members of the formate/nitrite transport protein family function to shuttle substrate across the cytoplasmic membrane. In bacterial pathogens, the nitrite transport protein is involved in protecting bacteria from peroxynitrite released by host macrophages. We have determined the 2.13-{angstrom} structure of the formate channel FocA from Vibrio cholerae, which reveals a pentamer in which each monomer possesses its own substrate translocation pore. Unexpectedly, the fold of the FocA monomer resembles that found in water and glycerol channels. The selectivity filter in FocA consists of a cytoplasmic slit and a central constriction ring. A 2.5-{angstrom} high-formate structure shows two formate ions bound to the cytoplasmic slit via both hydrogen bonding and van der Waals interactions, providing a structural basis for the substrate selectivity of the channel.

  15. Hydraulic jumps in a channel

    DEFF Research Database (Denmark)

    Bonn, D.; Andersen, Anders Peter; Bohr, Tomas

    2009-01-01

    We present a study of hydraulic jumps with flow predominantly in one direction, created either by confining the flow to a narrow channel with parallel walls or by providing an inflow in the form of a narrow sheet. In the channel flow, we find a linear height profile upstream of the jump as expected...

  16. An improved channel assessment scheme

    KAUST Repository

    Bader, Ahmed

    2014-05-01

    A source node in a multihop network determines whether to transmit in a channel based on whether the channel is occupied by a packet transmission with a large number of relays; whether the source node is in the data tones back-off zone; and the source node is in the busy tone back-off zone.

  17. Channel's Concurrence and Quantum Teleportation

    Institute of Scientific and Technical Information of China (English)

    LING Yin-Sheng

    2005-01-01

    Concurrence can measure the entanglement property of a system. If the channel is a pure state, positive concurrence state can afford the good performance in the teleportation process. If the channel ia a mixed state, positive concurrence state cannot assure the good performance in the teleportation. The conditions of the positive concurrence and the quantum teleportation in the Heisenberg spin ring is derived.

  18. Voltage-Gated Channels as Causative Agents for Epilepsies

    OpenAIRE

    2008-01-01

    Problem statement: Epilepsy is a common neurological disorder that afflicts 1-2% of the general population worldwide. It encompasses a variety of disorders with seizures. Approach: Idiopathic epilepsies were defined as a heterogeneous group of seizure disorders that show no underlying cause .Voltage-gated ion channels defect were recognized etiology of epilepsy in the central nervous system. The aim of this article was to provide an update on voltage-gated ...

  19. Signal Transduction at the Domain Interface of Prokaryotic Pentameric Ligand-Gated Ion Channels

    Science.gov (United States)

    Bertozzi, Carlo; Zimmermann, Iwan; Engeler, Sibylle; Hilf, Ricarda J. C.; Dutzler, Raimund

    2016-01-01

    Pentameric ligand-gated ion channels are activated by the binding of agonists to a site distant from the ion conduction path. These membrane proteins consist of distinct ligand-binding and pore domains that interact via an extended interface. Here, we have investigated the role of residues at this interface for channel activation to define critical interactions that couple conformational changes between the two structural units. By characterizing point mutants of the prokaryotic channels ELIC and GLIC by electrophysiology, X-ray crystallography and isothermal titration calorimetry, we have identified conserved residues that, upon mutation, apparently prevent activation but not ligand binding. The positions of nonactivating mutants cluster at a loop within the extracellular domain connecting β-strands 6 and 7 and at a loop joining the pore-forming helix M2 with M3 where they contribute to a densely packed core of the protein. An ionic interaction in the extracellular domain between the turn connecting β-strands 1 and 2 and a residue at the end of β-strand 10 stabilizes a state of the receptor with high affinity for agonists, whereas contacts of this turn to a conserved proline residue in the M2-M3 loop appear to be less important than previously anticipated. When mapping residues with strong functional phenotype on different channel structures, mutual distances are closer in conducting than in nonconducting conformations, consistent with a potential role of contacts in the stabilization of the open state. Our study has revealed a pattern of interactions that are crucial for the relay of conformational changes from the extracellular domain to the pore region of prokaryotic pentameric ligand-gated ion channels. Due to the strong conservation of the interface, these results are relevant for the entire family. PMID:26943937

  20. Signal Transduction at the Domain Interface of Prokaryotic Pentameric Ligand-Gated Ion Channels.

    Directory of Open Access Journals (Sweden)

    Carlo Bertozzi

    2016-03-01

    Full Text Available Pentameric ligand-gated ion channels are activated by the binding of agonists to a site distant from the ion conduction path. These membrane proteins consist of distinct ligand-binding and pore domains that interact via an extended interface. Here, we have investigated the role of residues at this interface for channel activation to define critical interactions that couple conformational changes between the two structural units. By characterizing point mutants of the prokaryotic channels ELIC and GLIC by electrophysiology, X-ray crystallography and isothermal titration calorimetry, we have identified conserved residues that, upon mutation, apparently prevent activation but not ligand binding. The positions of nonactivating mutants cluster at a loop within the extracellular domain connecting β-strands 6 and 7 and at a loop joining the pore-forming helix M2 with M3 where they contribute to a densely packed core of the protein. An ionic interaction in the extracellular domain between the turn connecting β-strands 1 and 2 and a residue at the end of β-strand 10 stabilizes a state of the receptor with high affinity for agonists, whereas contacts of this turn to a conserved proline residue in the M2-M3 loop appear to be less important than previously anticipated. When mapping residues with strong functional phenotype on different channel structures, mutual distances are closer in conducting than in nonconducting conformations, consistent with a potential role of contacts in the stabilization of the open state. Our study has revealed a pattern of interactions that are crucial for the relay of conformational changes from the extracellular domain to the pore region of prokaryotic pentameric ligand-gated ion channels. Due to the strong conservation of the interface, these results are relevant for the entire family.

  1. Quantum channel capacities - multiparty communication

    CERN Document Server

    Demianowicz, M; Demianowicz, Maciej; Horodecki, Pawel

    2006-01-01

    We analyze different aspects of multiparty communication over quantum memoryless channels and generalize some of key results known from bipartite channels to that of multiparty scenario. In particular, we introduce multiparty versions of minimal subspace transmission fidelity and entanglement transmission fidelity. We also provide alternative, local, versions of fidelities and show their equivalence to the global ones in context of capacity regions defined. The equivalence of two different capacity notions with respect to two types of the fidelities is proven. In analogy to bipartite case it is shown, via sufficiency of isometric encoding theorem, that additional classical forward side channel does not increase capacity region of any quantum channel with $k$ senders and $m$ receivers which represents a compact unit of general quantum networks theory. The result proves that recently provided capacity region of multiple access channel ([M. Horodecki et al, Nature {\\bf 436} 673 (2005)], [J.Yard et al, quant-ph/0...

  2. Channelling, a new immunization strategy.

    Science.gov (United States)

    Gacharna Romero, M G; Silva Pizano, E; Avendano Lamo, J

    1985-01-01

    In 1981, with PAHO/WHO technical assistance, the Ministry of Health, Colombia, designed what is known as the channelling strategy, aimed at improving immunization coverage. This name was given because the strategy is designed to establish communication channels through direct action aimed at promoting health. Health workers and community leaders or guides conduct household visits to identify unvaccinated children or those with incomplete vaccination schedules and "channel" them to health centers or health posts. The channelling strategy developed in Colombia was briefly mentioned in the case study on the Colombian Vaccination Crusade of 1984. It is now being employed for ORT and other PHC components in the Colombian Child Survival and Development Plan, 1985-1987. In the meantime, other countries have adopted the channelling strategy, which is described in this article.

  3. Canonical framework for multi-channel SAR-GMTI

    Institute of Scientific and Technical Information of China (English)

    Liu Congfeng; Liao Guisheng

    2008-01-01

    Synthetic aperture radar (SAR) systems have become an important tool for fine-resolution mapping and other remote sensing operations.The multi-channel SAR ground moving-target indication (GMTI) must process its data to produce not only the image of surveillance area but also the information of the ground moving-targets.The topic of moving-target detection in clutter has been extensively studied,and there are many methods that are used to detect moving targets,such as displaced phase center antenna (DPCA) method,along-track interfero-metric (ATI) phase,space-time adaptive processing (STAP),or some other metrics.A canonical framework is proposed that encompasses all the multi-channel SAR-GMT methods,namely,DPCA and ATI.The statistical test metric for multi-channel SAR-GMTI is established in a simple form,via the definition of the complex central Wishart distribution,to deduce the statistics of the test metric,and the probability distribution of the test metric for multichannel SAR-GMTI has the complex central Wishart distribution of 1×1 case,namely the x2 distribution.The theory foundation offers the possibility to construct the united multi-channel SAR-GMTI detector,and derives the constant false alarm rate (CFAR) detector tests for separating moving targets from clutter.

  4. Partitioning Residue-derived and Residue-induced Emissions of N2O Using 15N-labelled Crop Residues

    Science.gov (United States)

    Farrell, R. E.; Carverhill, J.; Lemke, R.; Knight, J. D.

    2014-12-01

    Estimates of N2O emissions in Canada indicate that 17% of all agriculture-based emissions are associated with the decomposition of crop residues. However, research specific to the western Canadian prairies (including Saskatchewan) has shown that the N2O emission factor for N sources in this region typically ranges between 0.2 and 0.6%, which is well below the current IPCC default emission factor of 1.0%. Thus, it stands to reason that emissions from crop residues should also be lower than those calculated using the current IPCC emission factor. Current data indicates that residue decomposition, N mineralization and N2O production are affected by a number of factors such as C:N ratio and chemical composition of the residue, soil type, and soil water content; thus, a bench-scale incubation study was conducted to examine the effects of soil type and water content on N2O emissions associated with the decomposition of different crop residues. The study was carried out using soils from the Black, Dark Brown, Brown, and Gray soil zones and was conducted at both 50% and 70% water-filled pore space (WFPS); the soils were amended with 15N-labeled residues of wheat, pea, canola, and flax, or with an equivalent amount of 15N-labeled urea; 15N2O production was monitored using a Picarro G5101-i isotopic N2O analyzer. Crop residue additions to the soils resulted in both direct and indirect emissions of N2O, with residue derived emissions (RDE; measured as 15N2O) generally exceeding residue-induced emissions (RIE) at 50% WFPS—with RDEs ranging from 42% to 88% (mean = 58%) of the total N2O. Conversely, at 70% WFPS, RDEs were generally lower than RIEs—ranging from 21% to 83% (mean = 48%). Whereas both water content and soil type had an impact on N2O production, there was a clear and consistent trend in the emission factors for the residues; i.e., emissions were always greatest for the canola residue and lowest for the wheat residue and urea fertilizer; and intermediate for pea

  5. Eluvial gold placer formation on actively rising mountain ranges, Central Otago, New Zealand

    Science.gov (United States)

    Craw, D.; Youngson, J. H.

    1993-05-01

    Eluvial gold deposits in Central Otago, New Zealand, have formed and are still forming on the flanks of actively rising antiformal mountain ranges. These gold deposits are derived mainly by erosion and concentration of fine-grained ( soil and sequences (up to 60 m thick) of poorly sorted immature schist gravels. The gravel sequences consist mainly of matrix-supported mass flow deposits and channellised proximal fan deposits, intercalated on a 1-10 m scale. Gold is concentrated in coarse lag gravels (up to 40 cm clasts) at channel bases. Topographic slopes on the rising ranges show an evolutionary trend in space and time, from gentle weakly dissected surfaces, through slightly degraded but convex slopes, to deeply incised convex streams. Eluvial gold occurs sporadically on the gentle slopes, but the most efficient concentration processes occurred where steeper convex slopes yielded an apron of fan sediments. Gold concentration at these sites resulted from selective and localized removal ("winnowing") of most schist debris, leaving coarse lag gravels and gold. The combination of authigenic grain size increase and residual concentration ensures that the eluvial deposits retain coarse-grained gold, and that only fine-grained gold is released to the alluvial systems downstream.

  6. The Wiretap Channel with Feedback: Encryption over the Channel

    CERN Document Server

    Lai, Lifeng; Poor, H Vincent

    2007-01-01

    In this work, the critical role of noisy feedback in enhancing the secrecy capacity of the wiretap channel is established. Unlike previous works, where a noiseless public discussion channel is used for feedback, the feed-forward and feedback signals share the same noisy channel in the present model. Quite interestingly, this noisy feedback model is shown to be more advantageous in the current setting. More specifically, the discrete memoryless modulo-additive channel with a full-duplex destination node is considered first, and it is shown that the judicious use of feedback increases the perfect secrecy capacity to the capacity of the source-destination channel in the absence of the wiretapper. In the achievability scheme, the feedback signal corresponds to a private key, known only to the destination. In the half-duplex scheme, a novel feedback technique that always achieves a positive perfect secrecy rate (even when the source-wiretapper channel is less noisy than the source-destination channel) is proposed....

  7. Ethanol production from bread residues

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Fatemeh; Roodpeyma, Shapoor [Chemical Engineering Department, Isfahan University of Technology, Isfahan (Iran); Khanahmadi, Morteza [Agricultural Engineering Research Department, Isfahan Center for the Research of Agricultural Science and Natural Resources, Isfahan (Iran); Taherzadeh, Mohammad J. [School of Engineering, University of Boraas, SE-50190 Boraas (Sweden)

    2008-04-15

    Bread residues were converted into a suitable fermentation feed via a two-step starch hydrolysis using amylolytic enzymes. Wheat flour hydrolysis was also carried out at the same conditions for comparison. For the first stage, namely liquefaction, effects of temperature (50-85{sup o}C) and substrate concentration (20% and 35%) were investigated. The 3-h liquefaction of the 20% bread suspension made 70% of initial dry matter soluble regardless of the temperature. The liquefaction of the 35% bread suspension had to be carried out by a fed-batch method due to the pasty behavior of the suspension. It resulted in a 65% dissolution of the suspended bread at 85{sup o}C. Saccharification of the latter product led to a fermentation feedstock having a dextrose equivalent (DE) of more than 95 and almost 80% dissolution of the initial dry matter. The prepared feedstock was then cultivated using Saccharomyces cerevisiae, which resulted in an overall yield of 350 g ethanol per kg of initial bread dry matter. Staling of the bread for a week had no effect on liquefaction, saccharification and ethanol yield. (author)

  8. Thermal Insulation from Hardwood Residues

    Science.gov (United States)

    Sable, I.; Grinfelds, U.; Vikele, L.; Rozenberga, L.; Zeps, M.; Luguza, S.

    2015-11-01

    Adequate heat is one of the prerequisites for human wellbeing; therefore, building insulation is required in places where the outside temperature is not suitable for living. The climate change, with its rising temperatures and longer dry periods, promotes enlargement of the regions with conditions more convenient for hardwood species than for softwood species. Birch (Betula pendula) is the most common hardwood species in Latvia. The aim of this work was to obtain birch fibres from wood residues of plywood production and to form low-density thermal insulation boards. Board formation and production was done in the presence of water; natural binder, fire retardant and fungicide were added in different concentrations. Board properties such as density, transportability or resistance to particulate loss, thermal conductivity and reaction to fire were investigated. This study included thermal insulation boards with the density of 102-120 kg/m3; a strong correlation between density and the binder amount was found. Transportability also improved with the addition of a binder, and 0.1-0.5% of the binder was the most appropriate amount for this purpose. The measured thermal conductivity was in the range of 0.040-0.043 W/(m·K). Fire resistance increased with adding the fire retardant. We concluded that birch fibres are applicable for thermal insulation board production, and it is possible to diversify board properties, changing the amount of different additives.

  9. HYDROTHERMAL CRACKING OF RESIDUAL OILS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The hydrothermal cracking of heavy oils, such as Canadian oil sand bitumen and Arabian heavy vacuum residue, as well as their model compound were performed over sulfided Ni/Al2O3 and NiMo/Al2O3 catalysts under 663~703 K and 6.0~8.0 MPa of hydrogen pressure in a batch autoclave reactor. According to the reaction mechanism of hydrothermal cracking, a small amount of free redical initiators, such as di-tert-peroxide, sulfur, etc., was added into the feed to generate free redicals at lower temperature, and obviously showed promotional effect on the conversion of hydrocarbons. The reaction mechanisms of hydrothermal cracking as well as the enhancing effect of initiators were studied by a probe reaction with 1-phenyldodecane as a model compound. The hydrothermal cracking of hydrocarbon proceeded via free redical mechanism and hydrogenating quench. The initiators might easily generate free redicals under reaction temperature, these redicals might abstract H from hydrocarbon molecule and reasonably initiate the chain reactions, therefore, promote the conversion of hydrocarbon even at lower reaction temperature.

  10. Ammonia emission from crop residues : quantification of ammonia volatilization based on crop residue properties

    NARCIS (Netherlands)

    Ruijter, de F.J.; Huijsmans, J.F.M.

    2012-01-01

    This paper gives an overview of available literature data on ammonia volatilization from crop residues. From these data, a relation is derived for the ammonia emission depending on the N-content of crop residue.

  11. Characterization Report on Sand, Slag, and Crucible Residues and on Fluoride Residues

    Energy Technology Data Exchange (ETDEWEB)

    Murray, A.M.

    1999-02-10

    This paper reports on the chemical characterization of the sand, slag, and crucible (SS and C) residues and the fluoride residues that may be shipped from the Rocky Flats Environmental Technology Site (RFETS) to Savannah River Site (SRS).

  12. Sedimentary processes and development of the Zenisu deep-sea channel, Philippine Sea

    Institute of Scientific and Technical Information of China (English)

    WUShiguo; SakamotoIzumi

    2003-01-01

    Zenisu deep-sea channel originated from a volcanic arc region, Izu-Ogasawara Island Arc, and vanished in the Shikoku Basin of the Philippine Sea. According to the swath bathymetry, the deep-sea channel can be divided into three segments. They are Zenisu canyon, E-W fan channel and trough-axis channel. A lot of volcanic detritus were deposited in the Zenisu Trough via the deep-sea channel because it originated from volcanic arc settings. On the basis of the swath bathymetry, submersible and seismic reflection data, the deposits are characterized by turbidite and debrite deposits as those in the other major deep-sea channels. Erosion or few sediments were observed in the Zenisu canyon,whereas a lot of turbidites and debrites occurred in the E-W channel and trough axis channel. Cold seep communities,active fault and fluid flow were discovered along the lower slope of the Zenisu Ridge. Vertical sedimentary sequences in the Zenisu Trough consist of the four post-rift sequence units of the Shikoku Basin, among which Units A and B are two turbidite units. The development of Zenisu canyon is controlled by the N-S shear fault, the E-W fan channel is related to the E-W shear fault, and the trough-axis channel is related to the subsidence of central basin.

  13. Sedimentary processes and development of the Zenisu deep-sea channel, Philippine Sea

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Zenisu deep-sea channel originated from a volcanic arc region, Izu-Ogasawara Island Arc, and vanished in the Shikoku Basin of the Philippine Sea. According to the swath bathymetry, the deep-sea channel can be divided into three segments. They are Zenisu canyon, E-W fan channel and trough-axis channel. A lot of volcanic detritus were deposited in the Zenisu Trough via the deep-sea channel because it originated from volcanic arc settings. On the basis of the swath bathymetry, submersible and seismic reflection data, the deposits are characterized by turbidite and debrite deposits as those in the other major deep-sea channels. Erosion or few sediments were observed in the Zenisu canyon, whereas a lot of turbidites and debrites occurred in the E-W channel and trough axis channel. Cold seep communities, active fault and fluid flow were discovered along the lower slope of the Zenisu Ridge. Vertical sedimentary sequences in the Zenisu Trough consist of the four post-rift sequence units of the Shikoku Basin, among which Units A and B are two turbidite units. The development of Zenisu canyon is controlled by the N-S shear fault, the E-W fan channel is related to the E-W shear fault, and the trough-axis channel is related to the subsidence of central basin.

  14. Based on Channel Characteristics

    Directory of Open Access Journals (Sweden)

    Zhuo Hao

    2013-01-01

    Full Text Available A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks.

  15. Opening Channels of Communication

    Directory of Open Access Journals (Sweden)

    Clarice Moura Costa

    2009-03-01

    Full Text Available Psychosis, as described through a psychodynamic perspective, is conceptualized as an attempt to deny the enveloping reality to avoid contact with the other. Music therapy is a way to break this barrier of non-communication raised by the patients. The music therapy process is configured as a trinomial – action (making music/ relationship (action with the other/communication (musical or verbal voluntary expression of feelings and conflicts, which, although intrinsically connected, is perceived in a sequential process. Aulagnier asserts that psychic activity represents the conjunction of three modes of functioning: the original process, the primary process and the secondary process. The perception of sound passes through three phases, corresponding to each manner of functioning of the psychic system – the pleasure of hearing, the desire to listen (to the other and the imperative of meaning. The music therapy process offers a significant similarity with the theory proposed by Aulagnier. We propose the hypothesis that in music therapy, there is an opportunity to (reexperience very archaic phases in the constitution of the ego, but in a new manner, so helping to open communication channels. This theoretical hypothesis is illustrated by real examples of patients.

  16. Ergodic channel capacity of the spatial correlated rayleigh MIMO channel

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-ping; WU Ping; LIU Ai-jun

    2007-01-01

    The theoretical capacity of the spatial correlated Rayleigh multiple input multiple output (MIMO) channel is an important issue in MIMO technology. In this article, an ergodic channel capacity formula of the spatial correlated rayleigh MIMO channel is provided, which is deduced when two antennas exist at either the transmitter or the receiver. The multi-dimensional least-squares fit algorithm is employed to narrow the difference between the theoretical formula capacity and the practical capacity. Simulation results show that the theoretical capacity approaches the practical one closely.

  17. The central peak revisited

    Energy Technology Data Exchange (ETDEWEB)

    Shirane, G.

    1995-10-27

    The central peak in SrTiO{sub 3} was first observed by Riste and his collaborators in 1971. This was one of the key discoveries leading to an understanding of the dynamics of phase transitions. The most recent discovery of two length scales in SrTiO{sub 3} motivated a reinvestigation of the soft phonon and associated central peak by neutron scattering. These recent experiments shed new light on the nature of the central peak. It is now well established to be strongly sample dependent and it originates from defects in bulk crystals.

  18. Imaging central pain syndromes.

    Science.gov (United States)

    Veldhuijzen, Dieuwke S; Greenspan, Joel D; Kim, Jong H; Coghill, Robert C; Treede, Rolf-Detlef; Ohara, Shinji; Lenz, Frederick A

    2007-06-01

    Anatomic, functional, and neurochemical imaging studies have provided new investigative tools in the study of central pain. High-resolution imaging studies allow for precise determination of lesion location, whereas functional neuroimaging studies measure pathophysiologic consequences of injury to the central nervous system. Additionally, magnetic resonance spectroscopy evaluates lesion-induced neurochemical changes in specific brain regions that may be related to central pain. The small number of studies to date precludes definitive conclusions, but the recent findings provide information that either supports or refutes current hypotheses and can serve to generate new ideas.

  19. Cooperative Precoding with Limited Feedback for MIMO Interference Channels

    CERN Document Server

    Huang, Kaibin

    2010-01-01

    Multi-antenna precoding effectively mitigates the interference in wireless networks. However, the resultant performance gains can be significantly compromised in practice if the precoder design fails to account for the inaccuracy in the channel state information (CSI) feedback. This paper addresses this issue by considering finite-rate CSI feedback from receivers to their interfering transmitters in the two-user multiple-input-multiple-output (MIMO) interference channel, called \\emph{cooperative feedback}, and proposing a systematic precoder design. Specifically, each precoder is decomposed into inner and outer precoders for nulling interference and improving the data-link array gain, respectively. The inner precoders are further designed to suppress the residual interference resulting from the finite-rate cooperative feedback. To regulate such interference, additional scalar cooperative feedback signals are designed to control transmission power using different criteria including fixed interference margins, ...

  20. Residuals Management and Water Pollution Control Planning.

    Science.gov (United States)

    Environmental Protection Agency, Washington, DC. Office of Public Affairs.

    This pamphlet addresses the problems associated with residuals and water quality especially as it relates to the National Water Pollution Control Program. The types of residuals and appropriate management systems are discussed. Additionally, one section is devoted to the role of citizen participation in developing management programs. (CS)