WorldWideScience

Sample records for group ia excitatory

  1. On silicon group elements ejected by supernovae type IA

    Energy Technology Data Exchange (ETDEWEB)

    De, Soma; Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Brown, Edward F. [Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN 46556 (United States); Calder, Alan C. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY (United States); Townsley, Dean M. [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL (United States); Athanassiadou, Themis [Swiss National Supercomputing Centre, Via Trevano 131, 6900 Lugano (Switzerland); Chamulak, David A. [Physics Division, Argonne National Laboratory, Argonne, IL (United States); Hawley, Wendy [Laboratoire d' Astrophysique de Marseille, Marseille cedex 13 F-13388 (France); Jack, Dennis, E-mail: somad@asu.edu [Departamento de Astronomía, Universidad de Guanajuato, Apartado Postal 144, 36000 Guanajuato (Mexico)

    2014-06-01

    There is evidence that the peak brightness of a Type Ia supernova is affected by the electron fraction Y {sub e} at the time of the explosion. The electron fraction is set by the aboriginal composition of the white dwarf and the reactions that occur during the pre-explosive convective burning. To date, determining the makeup of the white dwarf progenitor has relied on indirect proxies, such as the average metallicity of the host stellar population. In this paper, we present analytical calculations supporting the idea that the electron fraction of the progenitor systematically influences the nucleosynthesis of silicon group ejecta in Type Ia supernovae. In particular, we suggest the abundances generated in quasi-nuclear statistical equilibrium are preserved during the subsequent freeze-out. This allows potential recovery of Y {sub e} at explosion from the abundances recovered from an observed spectra. We show that measurement of {sup 28}Si, {sup 32}S, {sup 40}Ca, and {sup 54}Fe abundances can be used to construct Y {sub e} in the silicon-rich regions of the supernovae. If these four abundances are determined exactly, they are sufficient to recover Y {sub e} to 6%. This is because these isotopes dominate the composition of silicon-rich material and iron-rich material in quasi-nuclear statistical equilibrium. Analytical analysis shows the {sup 28}Si abundance is insensitive to Y {sub e}, the {sup 32}S abundance has a nearly linear trend with Y {sub e}, and the {sup 40}Ca abundance has a nearly quadratic trend with Y {sub e}. We verify these trends with post-processing of one-dimensional models and show that these trends are reflected in the model's synthetic spectra.

  2. XPS spectra and electronic structure of Group IA sulfates

    Energy Technology Data Exchange (ETDEWEB)

    Wahlqvist, M. [Department of Chemistry, Inorganic Chemistry, Umea University, S-901 87 Umea (Sweden); Shchukarev, A. [Department of Chemistry, Inorganic Chemistry, Umea University, S-901 87 Umea (Sweden)], E-mail: andrei.shchukarev@chem.umu.se

    2007-05-15

    The results of systematic XPS measurements of Group IA (H, Li, Na, K, Rb and Cs) sulfates together with NaHSO{sub 4}, KHSO{sub 4} and (NH{sub 4}){sub 2}SO{sub 4} are presented. The experiments on the alkali metal salts were preformed on ground powders at both liquid nitrogen and room temperatures; concentrated sulfuric acid was measured as a fast-frozen liquid drop. Spectra from grounded and floated samples were compared, and no significant difference relating to charging effects was observed. The influence of grinding on surface chemistry of the powders is described. Such a mechanical activation produces mainly monohydrates on the surface of all sulfates. In the case of Na{sub 2}SO{sub 4}, an additional NaHSO{sub 4} surface phase seems to form that is not stable in vacuum even at liquid nitrogen temperatures. It was found that the binding energies (O 1s and S 2p) of sulfate ion decrease down the group. The shifts are discussed and related to ionicity of the metal-sulfate bond. The structure of XPS valence band spectra is in good agreement with cluster calculations of SO{sub 4}{sup 2-} and HSO{sub 4}{sup -} [A.A. Audi, P.M.A. Sherwood, Surf. Interface Anal. 29 (2000) 265]. While the energies of bisulfate bands are not influenced by the cation (H{sup +}, Na{sup +} or K{sup +}), the sulfate ones experience an increase in bond ionicity and demonstrate the same binding energy shifts as the core levels.

  3. Grouping Normal Type Ia Supernovae by UV to Optical Color Differences

    CERN Document Server

    Milne, Peter A; Roming, Peter W A; Bufano, Filomena; Gehrels, Neil

    2013-01-01

    Observations of many SNe Ia with the UVOT instrument on the Swift satellite has revealed that there exists order to the differences in the UV-OPT colors of normal SNe. We examine UV-OPT color curves for 25 SNe Ia, dividing them into 4 groups, finding that ~1/3 of these SNe Ia have bluer UV-OPT colors than the larger group, with these "NUV-blue" SNe Ia 0.4 mag bluer than the "NUV-red" SNe Ia in u-v. Another group of events feature colors similar to NUV-red SNe Ia in the u-v to uvw1-v colors, but similar to the NUV-blue SNe Ia in the uvm2-v color. We name these events "MUV-blue". The last group initially has colors similar to NUV-red SNe Ia, but with color curves that feature more modest changes than the larger NUV-red group. These "irregular" events are comprised of all the NUV-red events with the broadest optical peaks, which leads us to consider this minor group a subset of the NUV-red group. When so separated and the accounting is made for the rapid time evolution of the UV-OPT colors, we find that the scat...

  4. Effects of stimulation of group I afferents from flexor muscles on heterosynaptic facilitation of monosynaptic reflexes produced by Ia and descending inputs: a test for presynaptic inhibition.

    Science.gov (United States)

    Rudomin, P; Jiménez, I; Enriquez, M

    1991-01-01

    1. In the chloralose anesthetized cat, conditioning stimulation of group I flexor afferents depresses the monosynaptic potentials generated by Ia afferents in single spinal motoneurons or in populations of motoneurons without affecting the monosynaptic potentials produced by stimulation of descending fibers in the ipsilateral ventromedial fasciculus (VMF). 2. Heterosynaptic facilitation of monosynaptic reflexes was used to test changes in the presynaptic effectiveness of excitatory inputs with direct connections with motoneurons. We found that the heterosynaptic facilitation of Ia origin was reduced by conditioning stimulation of group I afferents from flexors, without affecting the heterosynaptic facilitation produced by stimulation of the VMF. 3. These results confirm and expand previous observations showing that the synaptic effectiveness of descending fibers synapsing with motoneurons is not subjected to a presynaptic control mechanism of the type acting on Ia fiber terminals, and provide further basis for the use of changes in heterosynaptic facilitation of monosynaptic reflexes of Ia origin as an estimate of changes in presynaptic inhibition of Ia fibers (Hultborn et al. 1987a).

  5. EnviroAtlas - Des Moines, IA - Ecosystem Services by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset presents environmental benefits of the urban forest in 312 block groups in Des Moines, IA. Carbon attributes, temperature reduction,...

  6. Grouping normal type Ia supernovae by UV to optical color differences

    Energy Technology Data Exchange (ETDEWEB)

    Milne, Peter A. [University of Arizona, Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85719 (United States); Brown, Peter J. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Roming, Peter W. A. [Space Science and Engineering Division, Southwest Research Corporation, P.O. Drawer 28510, San Antonio, TX 78228-0510 (United States); Bufano, Filomena [Universidad Andres Bello, Departmento de Cincias Fisicas, Avda. Republica 220, Santiago (Chile); Gehrels, Neil, E-mail: pbrown@physics.tamu.edu [NASA-Goddard Space Flight Center, Astrophysics Science Division, Codes 660.1 and 662, Greenbelt, MD 20771 (United States)

    2013-12-10

    Observations of many Type Ia supernovae (SNe Ia) for multiple epochs per object with the Swift Ultraviolet Optical Telescope instrument have revealed that there exists order to the differences in the UV-optical colors of optically normal supernovae (SNe). We examine UV-optical color curves for 23 SNe Ia, dividing the SNe into four groups, and find that roughly one-third of 'NUV-blue' SNe Ia have bluer UV-optical colors than the larger 'NUV-red' group. Two minor groups are recognized, 'MUV-blue' and 'irregular' SNe Ia. While we conclude that the latter group is a subset of the NUV-red group, containing the SNe with the broadest optical peaks, we conclude that the 'MUV-blue' group is a distinct group. Separating into the groups and accounting for the time evolution of the UV-optical colors lowers the scatter in two NUV-optical colors (e.g., u – v and uvw1 – v) to the level of the scatter in b – v. This finding is promising for extending the cosmological utilization of SNe Ia into the NUV. We generate spectrophotometry of 33 SNe Ia and determine the correct grouping for each. We argue that there is a fundamental spectral difference in the 2900-3500 Å wavelength range, a region suggested to be dominated by absorption from iron-peak elements. The NUV-blue SNe Ia feature less absorption than the NUV-red SNe Ia. We show that all NUV-blue SNe Ia in this sample also show evidence of unburned carbon in optical spectra, whereas only one NUV-red SN Ia features that absorption line. Every NUV-blue event also exhibits a low gradient of the Si II λ6355 absorption feature. Many NUV-red events also exhibit a low gradient, perhaps suggestive that NUV-blue events are a subset of the larger low-velocity gradient group.

  7. EnviroAtlas - Woodbine, IA - Ecosystem Services by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset presents environmental benefits of the urban forest in 1 block group in Woodbine, Iowa. Carbon attributes, temperature reduction, pollution...

  8. EnviroAtlas - Woodbine, IA - Park Access by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the block group population that is within and beyond an easy walking distance (500m) of a park entrance. Park entrances were included...

  9. EnviroAtlas - Woodbine, IA - Land Cover by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset describes the percentage of each block group that is classified as impervious, forest, and green space. Forest is combination of trees and...

  10. EnviroAtlas - Des Moines, IA - Demographics by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset is a summary of key demographic groups for the EnviroAtlas community. This dataset was produced by the US EPA to support research and online...

  11. Excitability changes of ankle extensor group Ia and Ib fibers during fictive locomotion in the cat.

    Science.gov (United States)

    Dueñas, S H; Rudomin, P

    1988-01-01

    The present study examines the modulation of gastrocnemius-soleus (GS) monosynaptic reflexes as well as the intraspinal threshold changes of GS group I primary afferent terminals ending in the intermediate and motor nuclei during fictive locomotion in high decerebrate cats. The amplitude of the monosynaptic reflexes (MSR's) evoked in the medial gastrocnemius by stimulation of the lateral gastrocnemius nerve was increased during the extensor (E) phase, decreased during the flexion (F) phase of the step cycle and remained transiently increased after spontaneous episodes of fictive stepping. The intraspinal threshold of populations and of single group Ia GS afferent fibers ending in the motor pool, as well as of single Ia and Ib fibers ending in the intermediate nucleus, showed a sustained reduction during the episodes of fictive locomotion with superimposed cyclic changes in phase with the step cycle. During fictive walking and trotting the reduction of the intraspinal threshold of both Ia and Ib fiber terminals was maximal during the middle or late portion of the F-phase. During fictive gallop elicited by stimulation of the superficial peroneus nerve, the decrease in the intraspinal threshold of the Ia afferent fibers occurred however in phase with the activity of the GS motoneurons. During episodes of fictive locomotion slow, sustained negative DC potential shifts lasting tents of seconds, reflecting an increase in the extracellular potassium concentration were recorded at the base of the dorsal horn and in the intermediate nucleus. The present findings support the existence of tonic and phasic depolarization of the intraspinal terminals of GS group Ia and Ib primary afferents during spontaneous fictive locomotion. It is suggested that accumulation of potassium ions in the extracellular space contributes mainly to the sustained depolarization of group I fibers. The phasic depolarization would be mostly due to the activation of specific sets of interneurons and may

  12. Group Ia afferents contribute to short-latency interlimb reflexes in the human biceps femoris muscle

    DEFF Research Database (Denmark)

    Stevenson, Andrew James Thomas; Kamavuako, Ernest Nlandu; Geertsen, Svend Sparre

    2017-01-01

    and velocity of the iKnee rotations. Methods 11 seated participants (mean age: 25 ± 5 years) performed a voluntary isometric knee extension with the ipsilateral leg and contralateral knee flexion to 10% of maximum voluntary contraction (MVC). A mechanical actuator (MTS-Systems Corporation) imposed i...... amplitudes (4 vs. 8°) at the same 150°/s velocity (p’s > 0.08). Conclusion Because fast conducting group Ia muscle spindle afferents are sensitive to changes in muscle stretch velocity, while group II spindle afferents are sensitive to changes in amplitude (Grey et al., JPhysiol., 2001; Matthews, Trends...... Neurosci., 1991), group Ia velocity sensitive muscle spindle afferents likely contribute to the short-latency crossed spinal reflexes in the cBF muscle following iKnee joint rotations. This supports the findings for the short-latency crossed responses in the human soleus muscle (Stubbs & Mrachacz...

  13. [Fruit consumption in a group of teenagers from Iaşi].

    Science.gov (United States)

    Albul, Adriana; Rada, Cornelia; Albu, M; Indrei, L L

    2009-01-01

    A goal for the national nutritional education program is represented by the increase of fruit consumption. Using specially designed questionaries a group of 127 teenagers from two different Iaşi high schools provided date related to thei daily fruit intake. Almost 40% of the teenagers use fresh fruits as part of their breakfast and a greater number use them as snacks (57.5%) or dessert (80.5%), with statistically insignificant differences between the two high schools. The fruit intake is adequate in the studied group and the programs that promote certain food habits must take into account the existing situation.

  14. Constraining anisotropy of the universe from different groups of type-Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Zhe; Li, Xin [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); Chinese Academy of Sciences, Theoretical Physics Center for Science Facilities, Beijing (China); Lin, Hai-Nan; Wang, Sai [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China)

    2014-03-15

    Recently released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. Inspired by this, anisotropic cosmological models have been proposed. We note that the Finsler-Randers spacetime provides an appropriate framework for the anisotropic cosmology. By adding an arbitrary 1-form to the Friedmann-Robertson-Walker line element, a privileged axis in the universe is picked out. The distance-redshift relation is modified to be direction-dependent. We wish that the anisotropic cosmological model may be tested crossly by independent observations. Type-Ia supernovae (SNe Ia) calibrated from four different light curve fitters are used to constrain the possible anisotropy of the universe. The magnitudes of anisotropy are all between 2-5 %, but the systematic uncertainty cannot be excluded. The directions of the privileged axis seem to differ from each other. The statistical significance is not high enough to make a convincing conclusion. Nevertheless, the 1σ contours in the (l,b) plane obtained from four groups of SNe Ia have an overlap, centering at (l,b) ∼ (170 , 0 ). Monte Carlo simulation shows that the anisotropy is unlikely to be caused by the selection effect. (orig.)

  15. Effects of leg muscle tendon vibration on group Ia and group II reflex responses to stance perturbation in humans

    Science.gov (United States)

    Bove, Marco; Nardone, Antonio; Schieppati, Marco

    2003-01-01

    Stretching the soleus (Sol) muscle during sudden toe-up rotations of the supporting platform in a standing subject evokes a short-latency response (SLR) and a medium-latency response (MLR). The aim of the present investigation was to further explore the afferent and spinal pathways mediating the SLR and MLR in lower limb muscles by means of tendon vibration. In seven subjects, toe-up or toe-down rotations were performed under: (1) control, (2) continuous bilateral vibration at 90 Hz of Achilles' tendon or tibialis anterior (TA) tendon, and (3) post-vibration conditions. Sol and TA background EMG activity and reflex responses were bilaterally recorded and analysed. Toe-up rotations induced SLRs and MLRs in Sol at average latencies of 40 and 66 ms, respectively. During vibration, the latency of both responses increased by about 2 ms. The area of the SLR significantly decreased during vibration, regardless of the underlying background activity, and almost returned to control value post-vibration. The area of Sol MLR was less influenced by vibration than SLR, the reduction being negligible with relatively high background activity. However, contrary to SLR, MLR was even more reduced post-vibration. Toe-down rotations induced no SLR in the TA, while a MLR was evoked at about 81 ms. The area of TA MLR decreased slightly during vibration but much more post-vibration. SLRs and MLRs were differently affected by changing the vibration frequency to 30 Hz: vibration had a negligible effect on the SLR, but still produced a significant effect on the MLR. The independence from the background EMG of the inhibitory effect of vibration upon the SLR suggests that vibration removes a constant amount of the Ia afferent input. This can be accounted for by either presynaptic inhibition of group Ia fibres or a ‘busy-line' phenomenon. The differential effect of vibration on SLRs and MLRs is compatible with the notions that spindle primaries have a higher sensitivity to vibration than

  16. Effects of leg muscle tendon vibration on group Ia and group II reflex responses to stance perturbation in humans.

    Science.gov (United States)

    Bove, Marco; Nardone, Antonio; Schieppati, Marco

    2003-07-15

    Stretching the soleus (Sol) muscle during sudden toe-up rotations of the supporting platform in a standing subject evokes a short-latency response (SLR) and a medium-latency response (MLR). The aim of the present investigation was to further explore the afferent and spinal pathways mediating the SLR and MLR in lower limb muscles by means of tendon vibration. In seven subjects, toe-up or toe-down rotations were performed under: (1) control, (2) continuous bilateral vibration at 90 Hz of Achilles' tendon or tibialis anterior (TA) tendon, and (3) post-vibration conditions. Sol and TA background EMG activity and reflex responses were bilaterally recorded and analysed. Toe-up rotations induced SLRs and MLRs in Sol at average latencies of 40 and 66 ms, respectively. During vibration, the latency of both responses increased by about 2 ms. The area of the SLR significantly decreased during vibration, regardless of the underlying background activity, and almost returned to control value post-vibration. The area of Sol MLR was less influenced by vibration than SLR, the reduction being negligible with relatively high background activity. However, contrary to SLR, MLR was even more reduced post-vibration. Toe-down rotations induced no SLR in the TA, while a MLR was evoked at about 81 ms. The area of TA MLR decreased slightly during vibration but much more post-vibration. SLRs and MLRs were differently affected by changing the vibration frequency to 30 Hz: vibration had a negligible effect on the SLR, but still produced a significant effect on the MLR. The independence from the background EMG of the inhibitory effect of vibration upon the SLR suggests that vibration removes a constant amount of the Ia afferent input. This can be accounted for by either presynaptic inhibition of group Ia fibres or a 'busy-line' phenomenon. The differential effect of vibration on SLRs and MLRs is compatible with the notions that spindle primaries have a higher sensitivity to vibration than

  17. Immobilization induces changes in presynaptic control of group Ia afferents in healthy humans

    DEFF Research Database (Denmark)

    Jensen, Jesper Lundbye; Nielsen, Jens Bo

    2008-01-01

    maximal voluntary plantar- and dorsiflexion torque (MVC) was significantly reduced and the maximal SOL H-reflex amplitude increased with no changes in Mmax. Decreased presynaptic inhibition of the Ia afferents likely contributed to the increase of the H-reflex size, since we observed a significant...

  18. Constraining anisotropy of the universe from different groups of type-Ia supernovae

    CERN Document Server

    Chang, Zhe; Lin, Hai-Nan; Wang, Sai

    2014-01-01

    Recent released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. Inspired by this, anisotropic cosmological models have been proposed. We note that the Finsler-Randers spacetime provides an appropriate framework for the anisotropic cosmology. By adding an arbitrary 1-form to the Friedmann-Robertson-Walker (FRW) line element, a privileged axis in the universe is picked out. The distance-redshift relation is modified to be direction-dependent. We wish that the anisotropic cosmological model may be tested crossly by independent observations. Type-Ia supernovae (SNe Ia) calibrated from four different light curve fitters are used to constrain possible anisotropy of the universe. The magnitudes of anisotropy are all between 2% --- 5%, but the systematic uncertainty cannot be excluded. The directions of privileged axis seem to differ from each other. The statistical significance is not high enough to make a convincing conclusion. Nevertheless, the $1\\sigma$ c...

  19. EnviroAtlas - Woodbine, IA - Residents with Potential Window Views of Trees by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the total block group population and the percentage of the block group population that has little access to potential window views of...

  20. EnviroAtlas - Woodbine, IA - Residents with Potential Window Views of Water by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset describes the block group population and the percentage of the block group population that has potential views of water bodies. A potential...

  1. EnviroAtlas - Des Moines, IA - Potential Window Views of Water by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset describes the block group population and the percentage of the block group population that has potential views of water bodies. A potential...

  2. EnviroAtlas - Woodbine, IA - BenMAP Results by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset demonstrates the effect of changes in pollution concentration on local populations in 1 block group in Woodbine, Iowa. The US EPA's...

  3. EnviroAtlas - Woodbine, IA - Greenspace Around Schools by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas data set shows the number of schools in each block group in the EnviroAtlas community boundary as well as the number of schools where less than 25%...

  4. EnviroAtlas - Woodbine, IA - Historic Places by Census Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset portrays the total number of historic places located within each Census Block Group (CBG). The historic places data were compiled from the...

  5. EnviroAtlas - Des Moines, IA - Park Access by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the block group population that is within and beyond an easy walking distance (500m) of a park entrance. Park entrances were included...

  6. EnviroAtlas - Des Moines, IA - Greenspace Around Schools by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas data set shows the number of schools in each block group in the EnviroAtlas community boundary as well as the number of schools where less than 25%...

  7. EnviroAtlas - Des Moines, IA - Historic Places by Census Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset portrays the total number of historic places located within each Census Block Group (CBG). The historic places data were compiled from the...

  8. EnviroAtlas - Des Moines, IA - BenMAP Results by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset demonstrates the effect of changes in pollution concentration on local populations in 312 block groups in Des Moines, Iowa. The US EPA's...

  9. EnviroAtlas - Des Moines, IA - Land Cover by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset describes the percentage of each block group that is classified as impervious, forest, green space, and agriculture. Forest is defined as...

  10. Constraining the Single-degenerate Channel of Type Ia Supernovae with Stable Iron-group Elements in SNR 3C 397

    Science.gov (United States)

    Dave, Pranav; Kashyap, Rahul; Fisher, Robert; Timmes, Frank; Townsley, Dean; Byrohl, Chris

    2017-05-01

    Recent Suzaku X-ray spectra of supernova remnant (SNR) 3C 397 indicate enhanced stable iron group element abundances of Ni, Mn, Cr, and Fe. Seeking to address key questions about the progenitor and explosion mechanism of 3C 397, we compute nucleosynthetic yields from a suite of multidimensional hydrodynamics models in the near-Chandrasekhar-mass, single-degenerate paradigm for Type Ia supernovae (SNe Ia). Varying the progenitor white dwarf (WD) internal structure, composition, ignition, and explosion mechanism, we find that the best match to the observed iron peak elements of 3C 397 are dense (central density ≥6 × 109 g cm-3), low-carbon WDs that undergo a weak, centrally ignited deflagration, followed by a subsequent detonation. The amount of 56Ni produced is consistent with a normal or bright normal SNe Ia. A pure deflagration of a centrally ignited, low central density (≃2 × 109 g cm-3) progenitor WD, frequently considered in the literature, is also found to produce good agreement with 3C 397 nucleosynthetic yields, but leads to a subluminous SN Ia event, in conflict with X-ray line width data. Additionally, in contrast to prior work that suggested a large supersolar metallicity for the WD progenitor for SNR 3C 397, we find satisfactory agreement for solar- and subsolar-metallicity progenitors. We discuss a range of implications our results have for the single-degenerate channel.

  11. Signal transmission from motor axons to group Ia muscle spindle afferents: frequency responses and second-order non-linearities.

    Science.gov (United States)

    Windhorst, U; Kokkoroyiannis, T; Laouris, Y; Meyer-Lohmann, J

    1994-03-01

    Spinal recurrent inhibition via Renshaw cells and proprioceptive feedback via skeletal muscle and muscle spindle afferents have been hypothesized to constitute a compound feedback system [Windhorst (1989) Afferent Control of Posture and Locomotion; Windhorst (1993) Robots and Biological Systems--Towards a New Bionics]. To assess their detailed functions, it is necessary to know their dynamic characteristics. Previously we have extensively described the properties of signal transmission from motor axons to Renshaw cells using random motor axon stimulation and data analysis methods based thereupon. Using the same methods, we here compare these properties, in the cat, with those between motor axons and group Ia muscle spindle afferents in terms of frequency responses and nonlinear features. The frequency responses depend on the mean rate (carrier rate) of activation of motor axons and on the strength of coupling between motor units and spindles. In general, they are those of a second-order low-pass system with a cut-off at fairly low frequencies. This contrasts with the dynamics of motor axon-Renshaw cell couplings which are those of a much broader band-pass with its peak in the range of c. 2-15 Hz [Christakos (1987) Neuroscience 23, 613-623]. The second-order non-linearities in motor unit-muscle spindle signal lines are much more diverse than those in motor axon-Renshaw cell couplings. Although the average strength of response declines with mean stimulus rate in both subsystems, there is no systematic relationship between the amount of non-linearity and the average response in the former, whilst there is in the latter. The qualitative appearance of motor unit-muscle spindle non-linearities was complicated as was the average response to motor unit twitches. Thus, whilst Renshaw cells appear to dynamically reflect motor output rather faithfully, muscle spindles seem to signal local muscle fibre length changes and their dynamics. This would be consistent with the

  12. Defining Photometric Peculiar Type Ia Supernovae

    CERN Document Server

    Gonzalez-Gaitan, S; Pignata, G; Forster, F; Gutierrez, C P; Bufano, F; Galbany, L; Folatelli, G; Phillips, M M; Hamuy, M; Anderson, J P; de Jaeger, T

    2014-01-01

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e. objects with light-curve characteristics such as later primary maxima and absence of secondary peak in redder filters. This method is capable of selecting out this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have similar photometric characteristics as 91bg-like SNe Ia, namely the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large up-coming wide field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  13. Defining photometric peculiar type Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T. [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hsiao, E. Y.; Phillips, M. M. [Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena (Chile); Folatelli, G. [Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa 277-8583 (Kavli IPMU, WPI) (Japan); Anderson, J. P., E-mail: sgonzale@das.uchile.cl [European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago (Chile)

    2014-11-10

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  14. PAD and PAH response patterns of group Ia- and Ib-fibers to cutaneous and descending inputs in the cat spinal cord.

    Science.gov (United States)

    Rudomin, P; Solodkin, M; Jiménez, I

    1986-10-01

    The characteristics of the primary afferent depolarization (PAD) of Ia- and Ib-fibers generated by segmental and descending inputs have been analyzed in the spinal cord of anesthetized cats. The PAD was inferred from the changes produced by conditioning inputs on the intraspinal stimulus current required to produce a constant antidromic firing of single group I afferent fibers from the gastrocnemius (GS) or posterior biceps and semitendinosus (PBSt) nerves. Group I GS and PBSt fibers ending in the intermediate nucleus could be classified in three different types according to their PAD patterns in response to stimulation of cutaneous nerves and of descending fibers. In one set of group I fibers stimulation of cutaneous nerves and of the ipsilateral brain stem reticular formation, or the contralateral red nucleus, produced no PAD, but was able to inhibit the PAD generated by stimulation of group I fibers from flexors (type A PAD pattern). PBSt nerve fibers with this PAD pattern had peripheral thresholds and conduction velocities between 1.01 and 1.56 times threshold and 76.3 to 118 m/s, respectively. A second set of group I fibers was found to be depolarized by cutaneous nerves as well as by stimulation of rubrospinal and reticulospinal fibers (type B PAD pattern). The peripheral thresholds and conduction velocities of PBSt afferent fibers with a type B PAD pattern were of 1.66-2.03 times threshold and 71-83 m/s, respectively. We found a third set of group I fibers that were also depolarized by reticulospinal and rubrospinal inputs, but not by cutaneous nerves that instead inhibited the PAD elicited by group I volleys in flexor nerves (type C PAD pattern). All PBSt afferent fibers with a type C PAD pattern, with the exception of two, had peripheral thresholds and velocities between 1.46 and 2.16 times threshold and between 72 and 89 m/s, respectively. Stimulation of the Deiter's nucleus was found to depolarize the intraspinal terminals of a small fraction of group I

  15. [Congenital disorder of glycosylation type Ia (CDG Ia) - underdiagnosed entity?].

    Science.gov (United States)

    Sätilä, Heli; Kuusela, Anna-Leena; Pietilä, Kati; Niinikoski, Harri; Keskinen, Päivi

    2016-01-01

    Congenital disorders of glycosylation (CDG) are a relatively recently identified group of multisystem disorders caused by defective glycosylation of N-glycosylated proteins. They mainly involve the central and peripheral nervous system, but other organ systems are involved as well. Type CDG Ia accounts for over 80% of cases, characterized by decreased activity of the enzyme phosphomannomutase caused by mutations in chromosome 16 PMM2 gene. Treatment of CDG Ia remains symptomatic.

  16. EnviroAtlas - Des Moines, IA - Residents with Minimal Potential Window Views of Trees by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the total block group population and the percentage of the block group population that has little access to potential window views of...

  17. The Number of Positive Pelvic Lymph Nodes and Multiple Groups of Pelvic Lymph Node Metastasis Influence Prognosis in Stage IA-IIB Cervical Squamous Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Yu Liu

    2015-01-01

    Full Text Available Background: Pelvic lymph node metastasis (LNM is an important prognostic factor in cervical cancer. Cervical squamous cell carcinoma accounts for approximately 75-80% of all cervical cancers. Analyses of the effects of the number of positive lymph nodes (LNs, unilateral versus bilateral pelvic LNM and a single group versus multiple groups of pelvic LNM on survival and recurrence of cervical squamous cell carcinoma are still lacking. The study aimed to analyze the effects of the number of positive pelvic LNs and a single group versus multiple groups of pelvic LNM on survival and recurrence. Methods: We performed a retrospective review of 296 patients diagnosed with Stage IA-IIB cervical squamous cell carcinoma who received extensive/sub-extensive hysterectomy with pelvic lymphadenectomy/pelvic LN sampling at Peking University People′s Hospital from November 2004 to July 2013. Ten clinicopathological variables were evaluated as risk factors for pelvic LNM: Age at diagnosis, gravidity, clinical stage, histological grade, tumor diameter, lymph-vascular space involvement (LVSI, depth of cervical stromal invasion, uterine invasion, parametrial invasion, and neoadjuvant chemotherapy. Results: The incidence of pelvic LNM was 20.27% (60/296 cases. Pelvic LNM (P = 0.00 was significantly correlated with recurrence. Pelvic LNM (P = 0.00, the number of positive pelvic LNs (P = 0.04 and a single group versus multiple groups of pelvic LNM (P = 0.03 had a significant influence on survival. Multivariate analysis revealed that LVSI (P = 0.00, depth of cervical stromal invasion (P = 0.00 and parametrial invasion (P = 0.03 were independently associated with pelvic LNM. Conclusions: Patients with pelvic LNM had a higher recurrence rate and poor survival outcomes. Furthermore, more than 2 positive pelvic LNs and multiple groups of pelvic LNM appeared to identify patients with worse survival outcomes in node-positive IA-IIB cervical squamous cell carcinoma. LVSI

  18. Cervical Cancer Stage IA

    Science.gov (United States)

    ... hyphen, e.g. -historical Searches are case-insensitive Cervical Cancer Stage IA Add to My Pictures View /Download : ... 1500x1200 View Download Large: 3000x2400 View Download Title: Cervical Cancer Stage IA Description: Stage IA1 and IA2 cervical ...

  19. The anti-inflammatory activity of standard aqueous stem bark extract of Mangifera indica L. as evident in inhibition of Group IA sPLA2.

    Science.gov (United States)

    Dhananjaya, Bhadrapura Lakkappa; Shivalingaiah, Sudharshan

    2016-03-01

    The standard aqueous stem bark extract is consumed as herbal drink and used in the pharmaceutical formulations to treat patients suffering from various disease conditions in Cuba. This study was carried out to evaluate the modulatory effect of standard aqueous bark extract of M. indica on Group IA sPLA2. M. indica extract, dose dependently inhibited the GIA sPLA2 (NN-XIa-PLA2) activity with an IC50 value 8.1 µg/ml. M. indica extract effectively inhibited the indirect hemolytic activity up to 98% at ~40 µg/ml concentration and at various concentrations (0-50 µg/ml), it dose dependently inhibited the edema formation. When examined as a function of increased substrate and calcium concentration, there was no relieve of inhibitory effect on the GIA sPLA2. Furthermore, the inhibition was irreversible as evidenced from binding studies. It is observed that the aqueous extract ofM. indica effectively inhibits sPLA2 and it is associated inflammatory activities, which substantiate their anti-inflammatory properties. The mode of inhibition could be due to direct interaction of components present in the extract, with sPLA2 enzyme. Further studies on understanding the principal constituents, responsible for the anti-inflammatory activity would be interesting to develop this into potent anti-inflammatory agent.

  20. The anti-inflammatory activity of standard aqueous stem bark extract of Mangifera indica L. as evident in inhibition of Group IA sPLA2

    Directory of Open Access Journals (Sweden)

    BHADRAPURA LAKKAPPA DHANANJAYA

    2016-03-01

    Full Text Available ABSTRACT The standard aqueous stem bark extract is consumed as herbal drink and used in the pharmaceutical formulations to treat patients suffering from various disease conditions in Cuba. This study was carried out to evaluate the modulatory effect of standard aqueous bark extract of M. indica on Group IA sPLA2. M. indica extract, dose dependently inhibited the GIA sPLA2 (NN-XIa-PLA2 activity with an IC50 value 8.1 µg/ml. M. indica extract effectively inhibited the indirect hemolytic activity up to 98% at ~40 µg/ml concentration and at various concentrations (0-50 µg/ml, it dose dependently inhibited the edema formation. When examined as a function of increased substrate and calcium concentration, there was no relieve of inhibitory effect on the GIA sPLA2. Furthermore, the inhibition was irreversible as evidenced from binding studies. It is observed that the aqueous extract ofM. indica effectively inhibits sPLA2 and it is associated inflammatory activities, which substantiate their anti-inflammatory properties. The mode of inhibition could be due to direct interaction of components present in the extract, with sPLA2 enzyme. Further studies on understanding the principal constituents, responsible for the anti-inflammatory activity would be interesting to develop this into potent anti-inflammatory agent.

  1. Integrated Assessment of forest bioenergy systems in Mediterranean basin areas: The case of Catalonia and the use of participatory IA-focus groups

    Energy Technology Data Exchange (ETDEWEB)

    Puy, Neus; Tabara, David; Bartroli Almera, Jordi [Institute of Environmental Sciences and Technology (ICTA), Autonomous University of Barcelona, Edifici Cn - Campus de la UAB, 08193 Bellaterra (Cerdanyola del Valles), Barcelona, Catalonia (Spain); Bartroli Molins, Jordi [Department of Chemistry, Autonomous University of Barcelona, Edifici Cn - Campus de la UAB, 08193 Bellaterra (Cerdanyola del Valles), Barcelona, Catalonia (Spain); Rieradevall, Joan [Chemical Engineering Department, Autonomous University of Barcelona, Edifici Cn - Campus de la UAB, 08193 Bellaterra (Cerdanyola del Valles), Barcelona, Catalonia (Spain)

    2008-06-15

    The present paper applies and adapts the methodology of integrated assessment focus groups (IA-FGs) in order to understand and analyse the enhancing factors, as well as the constraints which drive or limit the take-off and development of sustainable forest biomass energy systems in a selected large forested area of the Mediterranean basin. Our study provides both quantitative and qualitative data from Catalonia, Northeast Spain. We provide historical trends in forest expansion; an assessment of technological, socio-economic and ecological options of forest management; and plausible scenarios of its future evolution. Results show that while the opportunities and stakes are high, in Mediterranean countries, specific socio-ecologic factors need to be taken into account if forest biomass is to contribute decisively to securing renewable sources of energy in Europe, integrating landscape planning with resource policies or mitigating climate change. Among these key factors identified are property regimes, low productivity of Mediterranean forests and weak institutional capacity. Other elements such as logistics and supply difficulties and the lack of economic profitability of forest products constitute limitations identified in the implementation of bioenergy systems. Technological solutions alone, while important, are insufficient to ensure a prominent role of Southern Europe forest biomass management in the climate, landscape and sustainability energy policy challenge. (author)

  2. TYPE Ia SUPERNOVA CARBON FOOTPRINTS

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R. C.; Nugent, P. [Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 50B-4206, Berkeley, CA 94611 (United States); Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, 75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, 53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622 Lyon (France); and others

    2011-12-10

    We present convincing evidence of unburned carbon at photospheric velocities in new observations of five Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 days relative to maximum. Detections are based on the presence of relatively strong C II {lambda}6580 absorption 'notches' in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the five SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibit high-velocity (v > 20, 000 km s{sup -1}) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broadband light curve/color behavior: three of the five have relatively narrow light curves but also blue colors and a fourth may be a dust-reddened member of this family. Accounting for signal to noise and phase, we estimate that 22{sup +10}{sub -6%} of SNe Ia exhibit spectroscopic C II signatures as late as -5 days with respect to maximum. We place these new objects in the context of previously recognized carbon-positive SNe Ia and consider reasonable scenarios seeking to explain a physical connection between light curve properties and the presence of photospheric carbon. We also examine the detailed evolution of the detected carbon signatures and the surrounding wavelength regions to shed light on the distribution of carbon in the ejecta. Our ability to reconstruct the C II {lambda}6580 feature in detail under the assumption of purely spherical symmetry casts doubt on a 'carbon blobs' hypothesis, but does not rule out all asymmetric models. A low volume filling factor for carbon, combined with line-of-sight effects, seems unlikely to explain the scarcity of detected carbon in SNe Ia by itself.

  3. Tourette syndrome and excitatory substances: is there a connection?

    Science.gov (United States)

    Zou, Li-Ping; Wang, Ying; Zhang, Li-Ping; Zhao, Jian-Bo; Lu, Jin-Fang; Liu, Qun; Wang, Hang-Yan

    2011-05-01

    The objective of this study is to investigate the relationship between excitatory substances by testing the urine in children with Tourette syndrome (TS). We performed a control study involving 44 patients with TS and 44 normal children by investigating the children's daily eating habits. We used the gas chromatograph-mass spectrometer and liquid chromatograph-mass spectrometer from Agilent. Substances for detection included 197 excitatory substances prohibited by the International Olympic Committee and other substances with similar chemical structures or biological functions for urine samples. Forty-four patients who did not take any drugs in the past 2 weeks enrolled in the study. The positive rate in the experiment group was three cases, while it was negative in the control group. The level of 1-testosterone increased in one extremely severe TS patient who ate large amounts of puffed food and drank an average of 350 ml of cola per day. Cathine and other substances with similar chemical constitution or similar biological effects increased in one severe TS patient who ate bags of instant noodles daily, according to the high score of the Yale Global Tic Severity Scale. An increase in ephedrine type, testosterone, and stimulants may be related to the pathogenesis of TS. Unhealthy food possibly causes TS. The relationship between excitatory substances and TS needs to be explored with the goal of providing more information on diagnosing and treating TS.

  4. Type Ia Supernova Carbon Footprints

    CERN Document Server

    Thomas, R C; Aragon, C; Antilogus, P; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Hsiao, E Y; Kerschhaggl, M; Kowalski, M; Loken, S; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Rubin, D; Runge, K; Scalzo, R; Smadja, G; Tao, C; Weaver, B A; Wu, C; Brown, P J; Milne, P A

    2011-01-01

    We present convincing evidence of unburned carbon at photospheric velocities in new observations of 5 Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 d relative to maximum. Detections are based on the presence of relatively strong C II 6580 absorption "notches" in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the 5 SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibits high-velocity (v > 20,000 km/s) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broad band light curve/color behavior: Three of the 5 have relatively narrow light curves but also blue colors, and a fourth may be a dust-reddened member of this family. Accounting for signal-to-noise and phase, we ...

  5. An excitatory GABA loop operating in vivo

    Directory of Open Access Journals (Sweden)

    Guadalupe eAstorga

    2015-07-01

    Full Text Available While it has been proposed that the conventional inhibitory neurotransmitter GABA can be excitatory in the mammalian brain, much remains to be learned concerning the circumstances and the cellular mechanisms governing potential excitatory GABA action. Using a combination of optogenetics and two-photon calcium imaging in vivo, we find that activation of chloride-permeable GABAA receptors in parallel fibers of the cerebellar molecular layer of adult mice causes parallel fiber excitation. Stimulation of parallel fibers at submaximal stimulus intensities leads to GABA release from molecular layer interneurons, thus creating a positive feedback loop that enhances excitation near the center of an activated parallel fiber bundle. Our results imply that elevated chloride concentration can occur in specific intracellular compartments of mature mammalian neurons and suggest an excitatory role for GABAA receptors in the cerebellar cortex of adult mice.

  6. Monosynaptic Ia projections from intrinsic hand muscles to forearm motoneurones in humans

    Science.gov (United States)

    Marchand-Pauvert, V; Nicolas, G; Pierrot-Deseilligny, E

    2000-01-01

    Heteronymous Ia excitatory projections from intrinsic hand muscles to human forearm motoneurones (MNs) were investigated. Changes in firing probability of single motor units (MUs) in the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), extensor carpi radialis (ECR), extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) were studied after electrical stimuli were applied to the median and ulnar nerve at wrist level and to the corresponding homonymous nerve at elbow level.Homonymous facilitation, occurring at the same latency as the H reflex, and therefore attributed to monosynaptic Ia EPSPs, was found in all the sampled units. In many MUs an early facilitation was also evoked by heteronymous low-threshold afferents from intrinsic hand muscles. The low threshold (between 0.5 and 0.6 times motor threshold (MT)) and the inability of a pure cutaneous stimulation to reproduce this effect indicate that it is due to stimulation of group I muscle afferents.Evidence for a similar central delay (monosynaptic) in heteronymous as in homonymous pathways was accepted when the difference in latencies of the homonymous and heteronymous peaks did not differ from the estimated supplementary afferent conduction time from wrist to elbow level by more than 0.5 ms (conduction velocity in the fastest Ia afferents between wrist and elbow levels being equal to 69 m s−1).A statistically significant heteronymous monosynaptic Ia excitation from intrinsic hand muscles supplied by both median and ulnar nerves was found in MUs belonging to all forearm motor nuclei tested (although not in ECU MUs after ulnar stimulation). It was, however, more often found in flexors than in extensors, in wrist than in finger muscles and in muscles operating in the radial than in the ulnar side.It is argued that the connections of Ia afferents from intrinsic hand muscles to forearm MNs, which are stronger and more widely distributed than in the cat, might

  7. IA, I AM

    DEFF Research Database (Denmark)

    Munk, Timme Bisgaard; Mørk, Kristian

    2004-01-01

    Hvad er informationsarkitektur? Mørk & Munk gennemgår de forskellige metaforiske konstruktioner af begrebet og kommer med deres helt egen selvstændige definition. Informationsarkitektur er en samtale, strukturation, en klassifikationskamp og et konceptuelt blend. Læs hvorfor i dette working paper...... om et af de meste centrale begreber videnssamfundet. For nu er vi alle informationsarkitekter: IA, I AM....

  8. Rates and progenitors of type Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Wood-Vasey, William Michael [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    The remarkable uniformity of Type Ia supernovae has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, Type Ia supernovae exhibit intrinsic variation in both their spectra and observed brightness. The brightness variations have been approximately corrected by various methods, but there remain intrinsic variations that limit the statistical power of current and future observations of distant supernovae for cosmological purposes. There may be systematic effects in this residual variation that evolve with redshift and thus limit the cosmological power of SN Ia luminosity-distance experiments. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in Type Ia supernovae. Toward this end, the Nearby Supernova Factory has been designed to discover hundreds of Type Ia supernovae in a systematic and automated fashion and study them in detail. This project will observe these supernovae spectrophotometrically to provide the homogeneous high-quality data set necessary to improve the understanding and calibration of these vital cosmological yardsticks. From 1998 to 2003, in collaboration with the Near-Earth Asteroid Tracking group at the Jet Propulsion Laboratory, a systematic and automated searching program was conceived and executed using the computing facilities at Lawrence Berkeley National Laboratory and the National Energy Research Supercomputing Center. An automated search had never been attempted on this scale. A number of planned future large supernovae projects are predicated on the ability to find supernovae quickly, reliably, and efficiently in large datasets. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of Type Ia supernovae. This thesis presents a new method for

  9. Progenitors of type Ia supernovae

    CERN Document Server

    Maeda, Keiichi

    2016-01-01

    Natures of progenitors of type Ia Supernovae (SNe Ia) have not yet been clarified. There has been long and intensive discussion on whether the so-called single degenerate (SD) scenario or the double degenerate (DD) scenario, or anything else, could explain a major population of SNe Ia, but the conclusion has not yet been reached. With rapidly increasing observational data and new theoretical ideas, the field of studying the SN Ia progenitors has been quickly developing, and various new insights have been obtained in recent years. This article aims at providing a summary of the current situation regarding the SN Ia progenitors, both in theory and observations. It seems difficult to explain the emerging diversity seen in observations of SNe Ia by a single population, and we emphasize that it is important to clarify links between different progenitor scenarios and different sub-classes of SNe Ia.

  10. Optimizing IA-64 performance

    CERN Document Server

    Jarp, S

    2001-01-01

    Examines key features of the Itanium processor architecture and microarchitecture. The Itanium, originally known as the IA-64, is a 64-bit processor designed by Hewlett-Packard and Intel. In addition to the obvious performance gains that 64-bit addressing brings, the Itanium also supports performance-enhancing techniques such as predication, speculation, rotating registers, a wide parallel execution core, high clock speed, fast bus architecture, multiple execution units, and the like. Moreover, the Itanium is designed from the ground up around parallelism and uses a new kind of instruction set based on the Explicit Parallel Instruction Computing (EPIC) specification, which allows the processing of Windows-based and UNIX- based applications, among other features. Operating-system support for the IA-64 has been announced for 64-bit Windows, HP-UX, varieties of Linux, and AIX 51. The author shows how to achieve optimal code generation by a compiler or generate optimized sequences ofIA-64 assembly code to ensure ...

  11. A metric space for type Ia supernova spectra

    CERN Document Server

    Sasdelli, Michele; Aldering, G; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Benitez-Herrera, S; Bongard, S; Buton, C; Canto, A; Cellier-Holzem, F; Chen, J; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Feindt, U; Fink, M; Fleury, M; Fouchez, D; Gangler, E; Guy, J; Ishida, E E O; Kim, A G; Kowalski, M; Kromer, M; Lombardo, S; Mazzali, P A; Nordin, J; Pain, R; Pécontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Runge, K; Saunders, C; Scalzo, R; Smadja, G; Suzuki, N; Tao, C; Taubenberger, S; Thomas, R C; Tilquin, A; Weaver, B A

    2014-01-01

    We develop a new framework for use in exploring Type Ia Supernova (SN Ia) spectra. Combining Principal Component Analysis (PCA) and Partial Least Square analysis (PLS) we are able to establish correlations between the Principal Components (PCs) and spectroscopic/photometric SNe Ia features. The technique was applied to ~120 supernova and ~800 spectra from the Nearby Supernova Factory. The ability of PCA to group together SNe Ia with similar spectral features, already explored in previous studies, is greatly enhanced by two important modifications: (1) the initial data matrix is built using derivatives of spectra over the wavelength, which increases the weight of weak lines and discards extinction, and (2) we extract time evolution information through the use of entire spectral sequences concatenated in each line of the input data matrix. These allow us to define a stable PC parameter space which can be used to characterize synthetic SN Ia spectra by means of real SN features. Using PLS, we demonstrate that th...

  12. EnviroAtlas - Des Moines, IA - Atlas Area Boundary

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the boundary of the Des Moines, IA EnviroAtlas Community. It represents the outside edge of all the block groups included in the...

  13. Neuroinflammation and excitatory symptoms in bipolar disorder

    Directory of Open Access Journals (Sweden)

    Isabella Panaccione

    2015-01-01

    Full Text Available Neuroinflammation has been proposed as a strong biological factor underlying the development of neuropsychiatric diseases. A role for dysregulation of the immune system was initially suggested in depressive disorders and subsequently extended to other illnesses, including bipolar disorder (BD. Indeed, there is growing evidence confirming the presence of a generalized pro-inflammatory state in BD patients, involving alterations in cytokine, acute-phase proteins, and complement factor secretion, white blood cell differentiation, microglial activation, arachidonic acid signaling pathways, and increased oxidative stress markers. Medications commonly used to treat BD, such as lithium, antiepileptics and antipsychotics, show some immunoregulatory activity both in vitro and in vivo. The aim of our study was to review the role of different inflammatory mechanisms, specifically in the development of excitatory symptoms, via a systematic PubMed search of the literature. Despite the high variability of results among studies, we found evidence indicating specific alterations of the inflammatory response during manic and mixed states of BD. These findings may help to clarify some of the complex mechanisms underlying the development of excitatory symptoms and suggest a potential role for drugs targeting the inflammatory system as new therapeutic options.

  14. Pediatróia

    OpenAIRE

    Carmona da Mota, Henrique

    2014-01-01

    Os pediatras deram-se conta que tinham perdido o seu “ponto da situação”, o seu “estado da arte”, a sua rainha, a estrela polar por que se guiavam. Na lufa-lufa do trabalho diário não lhe tinham dado a atenção indispensável e ela teria ido para o outro lado do mar Egeu.Decidiram ir lá buscá-la; todos colaboraram na organização da empresa e, tendo sacrificado aos deuses e escolhido o dia fasto, rumaram a Tróia. Nem todos que alguns espartanos teriam que ficar para assegurar a defesa das suas c...

  15. The diversity of Type Ia Supernovae: evidence for systematics?

    CERN Document Server

    Benetti, S; Mazzali, P A; Turatto, M; Altavilla, G; Bufano, F; Elias-Rosa, N; Kotak, R; Pignata, G; Salvo, M; Stanishev, V

    2004-01-01

    The photometric and spectroscopic properties of 26 well observed Type Ia Supernovae (SNeIa) were analyzed with the aim to explore SNIa diversity. The sample includes (Branch-)normal SNe as well as extreme events like SNe 1991T and 1991bg, while the truly peculiar SNIa, SN2000cx and SN2002cx are not included in our sample . A statistical treatment reveals the existence of three different groups. The first group (FAINT) consists of faint SNeIa similar to SN1991bg, with low expansion velocities and rapid evolution of SiII velocity. A second group consists of ``normal'' SNeIa, also with high temporal velocity gradient (HVG), but with brighter mean absolute magnitude =-19.3 and higher expansion velocities than the FAINT SNe. The third group includes both ``normal'' and SN1991T-like SNeIa: these SNe populate a narrow strip in the SiII velocity evolution plot, with a small velocity gradient (SVG), but have absolute magnitudes similar to HVGs. While the FAINT and HVG SNeIa together seem to define a relation between R...

  16. Standardization of type Ia supernovae

    CERN Document Server

    Coelho, Rodrigo C V; Reis, Ribamar R R; Siffert, Beatriz B

    2014-01-01

    Type Ia supernovae (SNe Ia) have been intensively investigated due to its great homogeneity and high luminosity, which make it possible to use them as standardizable candles for the determination of cosmological parameters. In 2011, the physics Nobel prize was awarded for the discovery of the accelerating expansion of the Universe through observations of distant supernovae. This is a pedagogical article, aimed at those starting their study of that subject, in which we dwell on some topics related to the analysis of SNe Ia and their use in luminosity distance estimators. Here we investigate their spectral properties and light curve standardization, paying careful attention to the fundamental quantities directly related to the SNe Ia observables. Finally, we describe our own step-by-step implementation of a classical light curve fi?tter, the stretch, applying it to real data from the Carnegie Supernova Project.

  17. Morphology and physiology of excitatory neurons in layer 6b of the somatosensory rat barrel cortex.

    Science.gov (United States)

    Marx, Manuel; Feldmeyer, Dirk

    2013-12-01

    Neocortical lamina 6B (L6B) is a largely unexplored layer with a very heterogeneous cellular composition. To date, only little is known about L6B neurons on a systematic and quantitative basis. We investigated the morphological and electrophysiological properties of excitatory L6B neurons in the rat somatosensory barrel cortex using whole-cell patch-clamp recordings and simultaneous biocytin fillings. Subsequent histological processing and computer-assisted 3D reconstructions provided the basis for a classification of excitatory L6B neurons according to their structural and functional characteristics. Three distinct clusters of excitatory L6B neurons were identified: (C1) pyramidal neurons with an apical dendrite pointing towards the pial surface, (C2) neurons with a prominent, "apical"-like dendrite not oriented towards the pia, and (C3) multipolar spiny neurons without any preferential dendritic orientation. The second group could be further subdivided into three categories termed inverted, "tangentially" oriented and "horizontally" oriented neurons. Furthermore, based on the axonal domain two subcategories of L6B pyramidal cells were identified that had either a more barrel-column confined or an extended axonal field. The classification of excitatory L6B neurons provided here may serve as a basis for future studies on the structure, function, and synaptic connectivity of L6B neurons.

  18. Asymmetry between excitatory and inhibitory learning.

    Science.gov (United States)

    Harris, Justin A; Patterson, Angela E; Andrew, Benjamin J; Kwok, Dorothy W S; Loy, Ignacio

    2016-10-01

    Five experiments investigated how learning about the added feature in a feature-positive discrimination or feature-negative discrimination is related to the change in reinforcement rate that the feature signals. Rats were trained in a magazine-approach paradigm with 2 concurrent discriminations between A versus AX and B versus BY. In 2 experiments (1 and 3), X and Y signaled an increase of 0.3 in the probability of reinforcement, from 0.1 to 0.4 (A vs. AX), or from 0.6 to 0.9 (B vs. BY). After extended training, each session included probe test trials in which X and Y were presented alone (Experiment 1) or in compound with another excitatory conditional stimulus (CS), C (Experiment 3). There was no difference in response rate between the 2 types of test trial (X vs. Y; XC vs. YC), consistent with the fact that X and Y signaled the same absolute change in reinforcement. In Experiments 2 and 4, X and Y signaled a decrease of 0.3 in the probability of reinforcement, from 0.4 to 0.1 (A vs. AX) or from 0.9 to 0.6 (B vs. BY). Test trials in which X or Y was presented with C showed that X had greater inhibitory strength than Y, consistent with the fact that X signaled a larger relative change in reinforcement. This was confirmed in Experiment 5, in which X and Y had the same inhibitory strength on test after training in which they signaled the same relative change in reinforcement but different absolute changes (0.3 to 0.1 for A vs. AX; 0.9 to 0.3 for B vs. BY). The results show that excitatory conditioning is linearly related to the increase in reinforcement rate, whereas inhibitory learning is not linearly related to the decrease in reinforcement rate. Implications of this for theories of associative learning are discussed. (PsycINFO Database Record

  19. [The receptors involved in the excitatory effects of kynurenines].

    Science.gov (United States)

    Lapin, I P; Ryzhov, I V

    1989-01-01

    There is presented a brief review of the authors' and literature data on the excitatory and convulsant effects of kynurenines, mainly 1-kynurenine and quinolinic acid. Particular attention is given to the interactions of kynurenines with the excitatory and inhibitory amino acids, their receptors, benzodiazepine receptor complex, catecholamines, serotonin, acetylcholine. The following trends of studies on the neuroactivity of kynurenines seem to be promising: isolation of specific binding sites for the most active kynurenines--kynurenine, quinolinic and kynurenic acids, the interaction with other endogenous convulsants like beta-carbolines, endorphines, folates, etc., the search of the brain structures triggering or deferring the excitatory and convulsant effects of kynurenines.

  20. Progenitors of Supernovae Type Ia

    CERN Document Server

    Toonen, S; Bours, M; Zwart, S Portegies; Claeys, J; Mennekens, N; Ruiter, A

    2013-01-01

    Despite the significance of Type Ia supernovae (SNeIa) in many fields in astrophysics, SNeIa lack a theoretical explanation. The standard scenarios involve thermonuclear explosions of carbon/oxygen white dwarfs approaching the Chandrasekhar mass; either by accretion from a companion or by a merger of two white dwarfs. We investigate the contribution from both channels to the SNIa rate with the binary population synthesis (BPS) code SeBa in order to constrain binary processes such as the mass retention efficiency of WD accretion and common envelope evolution. We determine the theoretical rates and delay time distribution of SNIa progenitors and in particular study how assumptions affect the predicted rates.

  1. Excitatory amino acid transporters as potential drug targets

    DEFF Research Database (Denmark)

    Bunch, Lennart; Erichsen, Mette Navy; Jensen, Anders Asbjørn

    2009-01-01

    BACKGROUND: Excitatory amino acid transporters (EAATs) are transmembrane proteins responsible for the uptake of (S)-glutamate (Glu) from the synaptic cleft, thereby terminating the glutamatergic neurotransmitter signal. Today five subtypes have been identified. Except for EAAT2, their individual...

  2. Dust around Type Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lifan

    2005-10-20

    An explanation is given of the low value of R lambda triple bond A lambda/E(B - V), the ratio of absolute to selective extinction deduced from Type Ia supernova observations. The idea involves scattering by dust clouds located in the circumstellar environment, or at the highest velocity shells of the supernova ejecta. The scattered light tends to reduce the effective R lambda in the optical, but has an opposite effect in the ultraviolet. The presence of circumstellar dust can be tested by ultraviolet to near infrared observations and by multi-epoch spectropolarimetry of SNe Ia.

  3. The 'grey' assessment practice of IA screening

    DEFF Research Database (Denmark)

    Bidstrup, Morten

    2017-01-01

    ’ in Denmark. This article explores the prevalence, influence and applied rationale of grey IA. Through a questionnaire, data was collected from 121 IA practitioners working within the fields of environmental impact assessment and strategic environmental assessment. It was found that grey IA is a common......Research focusing on the practices surrounding screening in Impact Assessment (IA) is limited. Yet, it has been found that development proposals sometimes are adjusted through an informal dialog with IA practitioners prior to or during screening. Such practice is often referred to as ‘grey IA...... practice, which influences the outcomes of formal screening procedures through consideration of impacts on neighbours and spatial zones of protection. Grey IA is to some extent motivated by the opportunity to save the resources required for full-scale IA, but an additional ‘green’ rationale also exists...

  4. IAS 12 needs methodical approach

    NARCIS (Netherlands)

    Hafkenscheid, R.P.F.M.; Janssen, C.M.L.

    2009-01-01

    The article describes a methodology used to establish the expected value of uncertain tax positions. The Project Update on Income Taxes released by the International Accounting Standards Board (IASB) in September 2008 aims to reduce the differences between IAS 12 Income Taxes and the SFAS 109 Accoun

  5. Specification of excitatory neurons in the developing cerebral cortex: progenitor diversity and and environmental influences

    Directory of Open Access Journals (Sweden)

    Marcos R Costa

    2015-01-01

    Full Text Available The mature cerebral cortex harbors a heterogeneous population of glutamatergic neurons, organized into a highly intricate histological architecture. Classically, this mixed population of neurons was thought to be generated sequentially from a seemingly homogenous group of progenitors under the influence of external cues. This view, however, has been challenged in the last decade by evidences pointing to the existence of fate-restricted neuronal progenitors in the developing neocortex. Here, we review classical studies using cell transplantation, retroviral labeling and cell culture, as well as new data from genetic fate-mapping analysis, to discuss the lineage relationships between neocortical progenitors and subclasses of excitatory neurons. We also propose a temporal model to conciliate the existence of fate-restricted progenitors alongside multipotent progenitors in the neocortex. Finally, we discuss evidences for a critical period of plasticity among post mitotic excitatory cortical neurons when environmental influences could change neuronal cell fate.

  6. Constraints on intragroup stellar mass from hostless Type Ia supernova

    CERN Document Server

    McGee, Sean L

    2009-01-01

    We probe the diffuse stellar mass in a sample of 1401 low redshift galaxy groups (10E13 - 10E14 Msun/h) by examining the rate of hostless Type Ia supernova (SNe Ia) within the groups. We correlate the sample of confirmed SNe Ia from the SDSS supernova survey with the positions of our galaxy groups, as well as with the resolved galaxies within them. We find that 19 of the 59 SNe Ia within the group sample have no detectable host galaxy, with another three ambiguous instances. This gives a robust upper limit that a maximum of 2.69% +1.58%/-1.34% of the group's total mass arises from diffuse stars in the intragroup medium. After correcting for a contribution from ``prompt'' SNe occurring within galaxies, and including a contribution from those which arise in dwarf galaxies below our photometric limit, we find that only 1.32% +0.78%/-0.70% of the group's total mass is likely in the form of diffuse stellar mass. Combining this result with the galaxy stellar mass functions of Yang et al., we find that 47% +16%/-15%...

  7. Ultraviolet diversity of Type Ia Supernovae

    DEFF Research Database (Denmark)

    Foley, Ryan J.; Pan, Yen-Chen; Brown, P.;

    2016-01-01

    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high...

  8. Pregnancies in glycogen storage disease type Ia

    NARCIS (Netherlands)

    Martens, Danielle H. J.; Rake, Jan Peter; Schwarz, Martin; Ullrich, Kurt; Weinstein, David A.; Merkel, Martin; Sauer, Pieter J. J.; Smit, G. Peter A.

    2008-01-01

    OBJECTIVE: Reports on pregnancies in women with glycogen storage disease type Ia (GSD-Ia) are scarce. Because of improved life expectancy, pregnancy is becoming an important issue. We describe 15 pregnancies by focusing on dietary treatment, biochemical parameters, and GSD-Ia complications. STUDY DE

  9. Effects of excitatory amino acid antagonists on evoked and spontaneous excitatory potentials in guinea-pig hippocampus.

    Science.gov (United States)

    Cotman, C W; Flatman, J A; Ganong, A H; Perkins, M N

    1986-09-01

    Evoked and spontaneous excitatory post-synaptic potentials (e.p.s.p.s) at the mossy fibre input to CA3 pyramidal neurones were recorded intracellularly in slices from the guinea-pig hippocampus. The effects of several amino acid antagonists on these responses were examined. L-2-amino-4-phosphonobutyrate (L-AP4), L-serine-O-phosphate (L-SOP), kynurenate, and N-(p-bromobenzoyl)piperazine-2,3-dicarboxylate (pBB-PzDA) reduced the amplitude of evoked mossy fibre e.p.s.p.s without affecting membrane potential or input resistance. Antagonism of mossy fibre spontaneous miniature e.p.s.p.s (m.e.p.s.p.s) by these compounds fell into two groups. L-AP4 and L-SOP applied at concentrations that blocked evoked e.p.s.p.s did not affect amplitude distributions of spontaneous m.e.p.s.p.s. Kynurenate and pBB-PzDA significantly affected the amplitude distributions and reduced the mean amplitude of spontaneous m.e.p.s.p.s. These results are consistent with a presynaptic site of action for L-AP4 and L-SOP and a post-synaptic site of action for kynurenate and pBB-PzDA as antagonists of e.p.s.p.s at the guinea-pig mossy fibre-CA3 pyramidal neurone synapse.

  10. Effects of excitatory amino acid antagonists on evoked and spontaneous excitatory potentials in guinea-pig hippocampus.

    Science.gov (United States)

    Cotman, C W; Flatman, J A; Ganong, A H; Perkins, M N

    1986-01-01

    Evoked and spontaneous excitatory post-synaptic potentials (e.p.s.p.s) at the mossy fibre input to CA3 pyramidal neurones were recorded intracellularly in slices from the guinea-pig hippocampus. The effects of several amino acid antagonists on these responses were examined. L-2-amino-4-phosphonobutyrate (L-AP4), L-serine-O-phosphate (L-SOP), kynurenate, and N-(p-bromobenzoyl)piperazine-2,3-dicarboxylate (pBB-PzDA) reduced the amplitude of evoked mossy fibre e.p.s.p.s without affecting membrane potential or input resistance. Antagonism of mossy fibre spontaneous miniature e.p.s.p.s (m.e.p.s.p.s) by these compounds fell into two groups. L-AP4 and L-SOP applied at concentrations that blocked evoked e.p.s.p.s did not affect amplitude distributions of spontaneous m.e.p.s.p.s. Kynurenate and pBB-PzDA significantly affected the amplitude distributions and reduced the mean amplitude of spontaneous m.e.p.s.p.s. These results are consistent with a presynaptic site of action for L-AP4 and L-SOP and a post-synaptic site of action for kynurenate and pBB-PzDA as antagonists of e.p.s.p.s at the guinea-pig mossy fibre-CA3 pyramidal neurone synapse. PMID:3795109

  11. The amygdala excitatory/inhibitory balance in a valproate-induced rat autism model.

    Directory of Open Access Journals (Sweden)

    Hui-Ching Lin

    Full Text Available The amygdala is an important structure contributing to socio-emotional behavior. However, the role of the amygdala in autism remains inconclusive. In this study, we used the 28-35 days valproate (VPA-induced rat model of autism to observe the autistic phenotypes and evaluate their synaptic characteristics in the lateral nucleus (LA of the amygdala. The VPA-treated offspring demonstrated less social interaction, increased anxiety, enhanced fear learning and impaired fear memory extinction. Slice preparation and electrophysiological recordings of the amygdala showed significantly enhanced long-term potentiation (LTP while stimulating the thalamic-amygdala pathway of the LA. In addition, the pair pulse facilitation (PPF at 30- and 60-ms intervals decreased significantly. Whole-cell recordings of the LA pyramidal neurons showed an increased miniature excitatory postsynaptic current (EPSC frequency and amplitude. The relative contributions of the AMPA receptor and NMDA receptor to the EPSCs did not differ significantly between groups. These results suggested that the enhancement of the presynaptic efficiency of excitatory synaptic transmission might be associated with hyperexcitibility and enhanced LTP in LA pyramidal neurons. Disruption of the synaptic excitatory/inhibitory (E/I balance in the LA of VPA-treated rats might play certain roles in the development of behaviors in the rat that may be relevant to autism. Further experiments to demonstrate the direct link are warranted.

  12. Estimating the time course of population excitatory postsynaptic potentials in motoneurons of spastic stroke survivors.

    Science.gov (United States)

    Hu, Xiaogang; Suresh, Nina L; Rymer, William Z

    2015-03-15

    Hyperexcitable motoneurons are likely to contribute to muscle hypertonia after a stroke injury; however, the origins of this hyperexcitability are not clear. One possibility is that the effective duration of the Ia excitatory postsynaptic potential (EPSP) is prolonged, increasing the potential for temporal summation of EPSPs, making action potential initiation easier. Accordingly, the purpose of this study was to quantify the time course of EPSPs in motoneurons of stroke survivors. The experimental protocol, which was based on parameters derived from simulation, involved sequential subthreshold electrical stimuli delivered to the median nerve of hemispheric stroke survivors. The resulting H-reflex responses were recorded in the flexor carpi radialis muscle. H-reflex response probability was then used to quantify the time course of the underlying EPSPs in the motoneuron pool. A population EPSP was estimated based on the probability of evoking an H reflex from the second electrical stimulus in the absence of a reflex response to the first stimulus. The accuracy of this time-course estimate was quantified using a computer simulation that explored a range of feasible EPSP parameters. Our experimental results showed that in all five hemispheric stroke survivors the rate of decay of the population EPSP was consistently slower in spastic compared with the contralateral motoneuron pools. We propose that one potential mechanism for hyperexcitability of motoneurons in spastic stroke survivors may be linked to this prolongation of the Ia EPSP time course. Our subthreshold double-stimulation approach also provides a noninvasive tool for quantifying the time course of EPSPs in both healthy and pathological conditions.

  13. An Analysis of Department of Defense Instruction 8500.2 'Information Assurance (IA) Implementation.'

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Philip LaRoche

    2012-01-01

    The Department of Defense (DoD) provides its standard for information assurance in its Instruction 8500.2, dated February 6, 2003. This Instruction lists 157 'IA Controls' for nine 'baseline IA levels.' Aside from distinguishing IA Controls that call for elevated levels of 'robustness' and grouping the IA Controls into eight 'subject areas' 8500.2 does not examine the nature of this set of controls, determining, for example, which controls do not vary in robustness, how this set of controls compares with other such sets, or even which controls are required for all nine baseline IA levels. This report analyzes (1) the IA Controls, (2) the subject areas, and (3) the Baseline IA levels. For example, this report notes that there are only 109 core IA Controls (which this report refers to as 'ICGs'), that 43 of these core IA Controls apply without variation to all nine baseline IA levels and that an additional 31 apply with variations. This report maps the IA Controls of 8500.2 to the controls in NIST 800-53 and ITGI's CoBIT. The result of this analysis and mapping, as shown in this report, serves as a companion to 8500.2. (An electronic spreadsheet accompanies this report.)

  14. Dark Matter Ignition of Type Ia Supernovae.

    Science.gov (United States)

    Bramante, Joseph

    2015-10-02

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way.

  15. Effects of Ketamine on Neuronal Spontaneous Excitatory Postsynaptic Currents and Miniature Excitatory Postsynaptic Currents in the Somatosensory Cortex of Rats

    Directory of Open Access Journals (Sweden)

    Chengdong Yuan

    2016-07-01

    Full Text Available Background: Ketamine is a commonly used intravenous anesthetic which produces dissociation anesthesia, analgesia, and amnesia. The mechanism of ketamine-induced synaptic inhibition in high-level cortical areas is still unknown. We aimed to elucidate the effects of different concentrations of ketamine on the glutamatergic synaptic transmission of the neurons in the primary somatosensory cortex by using the whole-cell patch-clamp method. Methods: Sprague-Dawley rats (11–19 postnatal days, n=36 were used to obtain brain slices (300 μM. Spontaneous excitatory postsynaptic currents (data from 40 neurons were recorded at a command potential of -70 mV in the presence of bicuculline (a competitive antagonist of GABAA receptors, 30 μM and strychnine (glycine receptor antagonist, 30 μM. Miniature excitatory postsynaptic currents (data from 40 neurons were also recorded when 1 μM of tetrodotoxin was added into the artificial cerebrospinal fluid. We used GraphPad Prism5for statistical analysis. Significant differences in the mean amplitude and frequency were tested using the Student paired 2-tailed t test. Values of P<0.05 were considered significant. Results: Different concentrations of ketamine inhibited the frequency and amplitude of the spontaneous excitatory postsynaptic currents as well as the amplitude of the miniature excitatory postsynaptic currents in a concentration-dependent manner, but they exerted no significant effect on the frequency of the miniature excitatory postsynaptic currents. Conclusion: Ketamine inhibited the excitatory synaptic transmission of the neurons in the primary somatosensory cortex. The inhibition may have been mediated by a reduction in the sensitivity of the postsynaptic glutamatergic receptors.

  16. The Changing Fractions of Type Ia Supernova NUV-Optical Subclasses with Redshift

    CERN Document Server

    Milne, Peter A; Brown, Peter J; Narayan, Gautham

    2014-01-01

    UV and optical photometry of Type Ia supernovae (SNe Ia) at low redshift have revealed the existence of two distinct color groups, NUV-red and NUV-blue events. The color curves differ primarily by an offset, with the NUV-blue u- color curves bluer than the NUV-red curves by 0.4 mag. For a sample of 23 low-z SNe~Ia observed with Swift, the NUV-red group dominates by a ratio of 2:1. We compare rest-frame UV/optical spectrophotometry of intermediate and high-z SNe Ia with UVOT photometry and HST spectrophotometry of low-z SNe Ia, finding that the same two color groups exist at higher-z, but with the NUV-blue events as the dominant group. Within each red/blue group, we do not detect any offset in color for different redshifts, providing insight into how SN~Ia UV emission evolves with redshift. Through spectral comparisons of SNe~Ia with similar peak widths and phase, we explore the wavelength range that produces the UV/OPT color differences. We show that the ejecta velocity of NUV-red SNe is larger than that of N...

  17. Excitatory response of rabbit myometrium to nitric oxide in vitro.

    Science.gov (United States)

    Nakanishi, H; Matsuoka, I; Ono, T; Okawa, T; Katahira, K; Nakahata, N

    1996-05-01

    Nitric oxide (NO) at high concentration (approx. 33 microM) produced a marked excitation: increase of tension development or increase in amplitude of spontaneous contraction, in 7 out of 8 rabbit nonpregnant myometrial strips. One case produced an inhibition: disappearance of spontaneous contraction. A latent period of several sec usually preceded the excitation. The response of the myometrium to NO approx. 33 microM associated with remarkable increase in tissue cyclic GMP levels. NO approx. 33 microM reduced an inhibition, in 1 out of 3 myometrial strips taken from ovariectomized rabbits. Two cases produced an excitatory. A precursor of NO, L-Arginine 100 microM or an inhibitor of NO synthase, NG-nitro-L-arginine 100 microM also produced a transient weak excitatory response. On the contrary, 8-bromo-cyclic GMP 100 microM produced an inhibition. The excitatory response to NO 33 microM was almost unaffected by pretreatment with indomethacin 10 microM, whereas the spontaneous motility was remarkably depressed. The contractile response of the isolated rabbit myometrium to electrical field stimulation was almost unaffected by the pretreatment with L-arginine 100 microM or NG-nitro-L-arginine 100 microM. The present findings may indicate that NO has inhibitory and excitatory components on the mechanical activity of the rabbit isolated myometrium.

  18. Irregular persistent activity induced by synaptic excitatory feedback

    Directory of Open Access Journals (Sweden)

    Francesca Barbieri

    2007-11-01

    Full Text Available Neurophysiological experiments on monkeys have reported highly irregular persistent activity during the performance of an oculomotor delayed-response task. These experiments show that during the delay period the coefficient of variation (CV of interspike intervals (ISI of prefrontal neurons is above 1, on average, and larger than during the fixation period. In the present paper, we show that this feature can be reproduced in a network in which persistent activity is induced by excitatory feedback, provided that (i the post-spike reset is close enough to threshold , (ii synaptic efficacies are a non-linear function of the pre-synaptic firing rate. Non-linearity between presynaptic rate and effective synaptic strength is implemented by a standard short-term depression mechanism (STD. First, we consider the simplest possible network with excitatory feedback: a fully connected homogeneous network of excitatory leaky integrate-and-fire neurons, using both numerical simulations and analytical techniques. The results are then confirmed in a network with selective excitatory neurons and inhibition. In both the cases there is a large range of values of the synaptic efficacies for which the statistics of firing of single cells is similar to experimental data.

  19. Type Ia supernova science 2010-2020

    CERN Document Server

    Howell, D A; Della Valle, M; Nugent, P E; Perlmutter, S; Marion, G H; Krisciunas, K; Badenes, C; Mazzali, P; Aldering, G; Antilogus, P; Baron, E; Becker, A; Baltay, C; Benetti, S; Blondin, S; Branch, D; Brown, E F; Deustua, S; Ealet, A; Ellis, Richard S; Fouchez, D; Freedman, W; Gal-Yam, A; Jha, S; Kasen, D; Kessler, R; Kim, A G; Leonard, D C; Li, W; Livio, M; Maoz, D; Mannucci, F; Matheson, T; Neill, J D; Nomoto, K; Panagia, N; Perrett, K; Phillips, M; Poznanski, D; Quimby, R; Rest, A; Riess, A; Sako, M; Soderberg, A M; Strolger, L; Thomas, R; Turatto, M; van Dyk, S; Wood-Vasey, W M

    2009-01-01

    In the next decade Type Ia supernovae (SNe Ia) will be used to test theories predicting changes in the Dark Energy equation of state with time. Ultimately this requires a dedicated space mission like JDEM. SNe Ia are mature cosmological probes --- their limitations are well characterized, and a path to improvement is clear. Dominant systematic errors include photometric calibration, selection effects, reddening, and population-dependent differences. Building on past lessons, well-controlled new surveys are poised to make strides in these areas: the Palomar Transient Factory, Skymapper, La Silla QUEST, Pan-STARRS, the Dark Energy Survey, LSST, and JDEM. They will obviate historical calibrations and selection biases, and allow comparisons via large subsamples. Some systematics follow from our ignorance of SN Ia progenitors, which there is hope of determining with SN Ia rate studies from 0Ia regulate galactic and cluster chemical evolution, inform stellar evolution, and are ...

  20. Type Ia supernovae: explosions and progenitors

    Science.gov (United States)

    Kerzendorf, Wolfgang Eitel

    2011-08-01

    Supernovae are the brightest explosions in the universe. Supernovae in our Galaxy, rare and happening only every few centuries, have probably been observed since the beginnings of mankind. At first they were interpreted as religious omens but in the last half millennium they have increasingly been used to study the cosmos and our place in it. Tycho Brahe deduced from his observations of the famous supernova in 1572, that the stars, in contrast to the widely believe Aristotelian doctrine, were not immutable. More than 400 years after Tycho made his paradigm changing discovery using SN 1572, and some 60 years after supernovae had been identified as distant dying stars, two teams changed the view of the world again using supernovae. The found that the Universe was accelerating in its expansion, a conclusion that could most easily be explained if more than 70% of the Universe was some previously un-identified form of matter now often referred to as `Dark Energy'. Beyond their prominent role as tools to gauge our place in the Universe, supernovae themselves have been studied well over the past 75 years. We now know that there are two main physical causes of these cataclysmic events. One of these channels is the collapse of the core of a massive star. The observationally motivated classes Type II, Type Ib and Type Ic have been attributed to these events. This thesis, however is dedicated to the second group of supernovae, the thermonuclear explosions of degenerate carbon and oxygen rich material and lacking hydrogen - called Type Ia supernovae (SNe Ia). White dwarf stars are formed at the end of a typical star's life when nuclear burning ceases in the core, the outer envelope is ejected, with the degenerate core typically cooling for eternity. Theory predicts that such stars will self ignite when close to 1.38 Msun (called the Chandrasekhar Mass). Most stars however leave white dwarfs with 0.6 Msun, and no star leaves a remnant as heavy as 1.38 M! sun, which suggests

  1. European freshwater VHSV genotype Ia isolates divide into two distinct subpopulations

    DEFF Research Database (Denmark)

    Kahns, Søren; Skall, Helle Frank; Kaas, Rolf Sommer;

    2012-01-01

    Viral haemorrhagic septicaemia (VHS), caused by the novirhabdovirus VHSV, often leads to significant economic losses to European rainbow trout production. The virus isolates are divided into 4 distinct genotypes with additional subgroups including sublineage Ia, isolates of which are the main...... detected in Denmark since January 2009. Full-length G-genes of all Danish VHSV isolates that were submitted for diagnostic analyses in the period 2004−2009 were sequenced and analysed. All 58 Danish isolates from rainbow trout grouped with sublineage Ia isolates. Furthermore, VHSV isolates from infected...... Danish freshwater catchments appear to have evolved into a distinct clade within sublineage Ia, herein designated clade Ia-1, whereas trout isolates originating from other continental European countries cluster in another distinct clade, designated clade Ia-2. In addition, phylogenetic analyses indicate...

  2. Gonorréia Gonorrhea

    Directory of Open Access Journals (Sweden)

    Gerson Oliveira Penna

    2000-10-01

    Full Text Available A gonorréia é uma infecção bacteriana freqüente, causada pela Neisseria gonorrhoeae, um diplococo Gram-negativo de transmissão quase que exclusiva através de contato sexual ou perinatal. Primariamente afeta membranas mucosas do trato genital inferior, e mais raramente, as mucosas do reto, orofaringe e conjuntiva. A infecção genital ascendente na mulher leva a uma complicação séria, a salpingite aguda, uma das principais causas de infertilidade feminina. A partir dos anos 90, deu-se início a um novo tempo no que se refere a descobertas sobre a patogenia da gonorréia e seu agente etiológico. O controle da gonorréia tem sido difícil na maioria das populações, e essa permanece um exemplo da influência que os fatores sociais, comportamentais e demográficos exercem na epidemiologia de uma doença infecciosa. O manejo da gonorréia e de outras doenças sexualmente transmissíveis requer tanto o tratamento do paciente e de seu parceiro sexual como medidas de saúde pública para interromper a transmissão da infecção e evitar complicações a longo prazo.Gonorrhea is a common bacterial infection caused by Neisseria gonorrhoeae, a Gram-negative diplococcus that is transmitted almost exclusively by sexual contact or perinatally. It primarily affects the mucous membranes of the lower genital tract and less frequently those of the rectum, oropharynx, and conjunctivae. Ascending genital infection in women leads to the predominant complication, acute salpingitis, one of the most common causes of female infertility in the world. Since the 1990s, a remarkable surge of information ensued regarding the pathogenesis of gonorrhea and its agent. Gonorrohea has proven difficult to control in most populations and remains a prime example of the influence that social, behavioral, and demographic factors can have on the epidemiology of an infectious disease. The management of gonorrhea and other sexually transmitted infections requires both

  3. Data of evolutionary structure change: 1C7IA-1P0IA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1C7IA-1P0IA 1C7I 1P0I A A THQIVTTQYGKVKGT--TE--NGVHKWKGIPYAKPPVGQ...GPFGFMHLSSFDEAYSDNLGLLDQAAALKWVRENISAFGGDPDNVTVFGESAGGMSIAALLAMPAAKGLFQKAIMESGAS----RTMTKEQAASTAAAFLQVLGINES...QLDRLHTVAAEDLLKA-----ADQLRIAE-----KENIFQLFFQPALDPKTLPEEPEKSIAEGAASGIPLLIGTTRDEGYF...TLELPFVFGNLDELERMAKAEITDEVKQLSHTIQSAWTTFAKTGNPST---EAVNWPAYHEESRETVILDS-EITIENDPESEKRQKLF------ --IIIA...WNPNTDLSEDCLYLNVWIPAPKPKNATVLIWIYGGGFQTGTSSLHVYDGKFLARVERVIVVSMNYRVGALGFLALPG-NPEAPGNMGLFDQQLALQWVQKNIAAFGGN

  4. Frequency of islet cell autoantibodies (IA-2 and GAD in young Brazilian type 1 diabetes patients

    Directory of Open Access Journals (Sweden)

    V.C. Pardini

    1999-10-01

    Full Text Available Type 1 diabetes, as an autoimmune disease, presents several islet cell-specific autoantibodies such as islet cell antibody (ICA, anti-insulin, anti-glutamic acid decarboxylase (GAD and the antibody (Ab against tyrosine phosphatase (PTP-like protein known as ICA-512 (IA-2. In order to determine the frequency of the anti-GAD and anti-IA-2 autoantibodies in Brazilian type 1 diabetes patients we studied 35 diabetes mellitus (DM type 1 patients with recent-onset disease (£12 months and 37 type 1 diabetes patients with long-duration diabetes (>12 months who were compared to 12 children with normal fasting glucose. Anti-GAD65 and anti-IA-2 autoantibodies were detected with commercial immunoprecipitation assays. The frequency of positive results in recent-onset DM type 1 patients was 80.0% for GADAb, 62.9% for IA-2Ab and 82.9% for GADAb and/or IA-2Ab. The long-duration type 1 diabetes subjects presented frequencies of 54.1% for GADAb and IA-2Ab, and 67.5% for GAD and/or IA-2 antibodies. The control group showed no positive cases. Anti-GAD and IA-2 assays showed a high frequency of positivity in these Brazilian type 1 diabetes patients, who presented the same prevalence as a Caucasian population.

  5. Bayesian Analysis of Type Ia Supernova Data

    Institute of Scientific and Technical Information of China (English)

    王晓峰; 周旭; 李宗伟; 陈黎

    2003-01-01

    Recently, the distances to type Ia supernova (SN Ia) at z ~ 0.5 have been measured with the motivation of estimating cosmological parameters. However, different sleuthing techniques tend to give inconsistent measurements for SN Ia distances (~0.3 mag), which significantly affects the determination of cosmological parameters.A Bayesian "hyper-parameter" procedure is used to analyse jointly the current SN Ia data, which considers the relative weights of different datasets. For a flat Universe, the combining analysis yields ΩM = 0.20 ± 0.07.

  6. EnviroAtlas - Des Moines, IA - EnviroAtlas Community Boundary

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the boundary of the Des Moines, IA EnviroAtlas Community. It represents the outside edge of all the block groups included in the...

  7. History of the IAS-Society and the IAS-conferences

    NARCIS (Netherlands)

    Hertzberger, B.; Kanade, T.; Groen, F.

    2017-01-01

    This paper describes the development of the IAS-Society and the trends in the Intelligent Autonomous Systems conferences. The first IAS conference was held in 1986 and was the first conference on this topic. The Society, founded in 1994, laid the basis for the organization of the IAS conferences. Th

  8. History of the IAS-Society and the IAS-conferences

    NARCIS (Netherlands)

    Hertzberger, B.; Kanade, T.; Groen, F.

    This paper describes the development of the IAS-Society and the trends in the Intelligent Autonomous Systems conferences. The first IAS conference was held in 1986 and was the first conference on this topic. The Society, founded in 1994, laid the basis for the organization of the IAS conferences.

  9. Intelligent Autonomous Systems 11: IAS-11

    NARCIS (Netherlands)

    Christensen, H.I.; Groen, F.; Petriu, E.

    2010-01-01

    This volume contains the proceedings of the eleventh International Conference on Intelligent Autonomous Systems (IAS-11) at the University of Ottawa in Canada. As ever, the purpose of the IAS conference is to bring together leading international researchers with an interest in all aspects of the

  10. The Local Hosts of Type Ia Supernovae

    CERN Document Server

    Neill, James D; Howell, D Andy; Conley, Alex; Seibert, Mark; Martin, D Christopher; Barlow, Tom A; Foster, Karl; Friedman, Peter G; Morrissey, Patrick; Neff, Susan G; Schiminovich, David; Wyder, Ted K; Bianchi, Luciana; Donas, José; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Milliard, Bruno; Rich, R Michael; Szalay, A S

    2009-01-01

    We use multi-wavelength, matched aperture, integrated photometry from GALEX, SDSS and the RC3 to estimate the physical properties of 166 nearby galaxies hosting 168 well-observed Type Ia supernovae (SNe Ia). Our data corroborate well-known features that have been seen in other SN Ia samples. Specifically, hosts with active star formation produce brighter and slower SNe Ia on average, and hosts with luminosity-weighted ages older than 1 Gyr produce on average more faint, fast and fewer bright, slow SNe Ia than younger hosts. New results include that in our sample, the faintest and fastest SNe Ia occur only in galaxies exceeding a stellar mass threshhold of ~10^10 M_sun, indicating that their progenitors must arise in populations that are older and/or more metal rich than the general SN Ia population. A low host extinction sub-sample hints at a residual trend in peak luminosity with host age, after correcting for light-curve shape, giving the appearance that older hosts produce less-extincted SNe Ia on average....

  11. EXCITATORY CONNECTIONS BETWEEN SPINAL MOTONEURONS IN THE ADULT RAT

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objectives. Dendro-dendritic and dendro-somatic projections are common between spinal motoneurons. We attempted to clarify whether there are functional connections through these projections.Methods. Motoneurons were antidromically stimulated by the muscle nerve and recorded intracellularly to examine the direct interaction between them, after the related dorsal roots had been cut.Results. Excitatory connections, demonstrated by depolarizing potentials in response to muscle nerve stimulation, were found between motoneurons innervating the same muscle or synergistic muscles, but never between motoneurons innervating antagonistic muscles. These potentials were finely graded in response to a series of increasing stimuli and resistant to high frequency (50Hz) stimulation.Conclusions.These results indicate that excitatory connections, with certain specificity of spatial and temporal distribution, occur in the spinal motoneurons. It is also suggested that electrical coupling should be involved in these connections and this mechanism should improve the excitability of the motoneurons in the same column.

  12. Sequential dynamics in the motif of excitatory coupled elements

    Science.gov (United States)

    Korotkov, Alexander G.; Kazakov, Alexey O.; Osipov, Grigory V.

    2015-11-01

    In this article a new model of motif (small ensemble) of neuron-like elements is proposed. It is built with the use of the generalized Lotka-Volterra model with excitatory couplings. The main motivation for this work comes from the problems of neuroscience where excitatory couplings are proved to be the predominant type of interaction between neurons of the brain. In this paper it is shown that there are two modes depending on the type of coupling between the elements: the mode with a stable heteroclinic cycle and the mode with a stable limit cycle. Our second goal is to examine the chaotic dynamics of the generalized three-dimensional Lotka-Volterra model.

  13. Excitatory GABA in rodent developing neocortex in vitro.

    Science.gov (United States)

    Rheims, Sylvain; Minlebaev, Marat; Ivanov, Anton; Represa, Alfonso; Khazipov, Rustem; Holmes, Gregory L; Ben-Ari, Yehezkel; Zilberter, Yuri

    2008-08-01

    GABA depolarizes immature cortical neurons. However, whether GABA excites immature neocortical neurons and drives network oscillations as in other brain structures remains controversial. Excitatory actions of GABA depend on three fundamental parameters: the resting membrane potential (Em), reversal potential of GABA (E(GABA)), and threshold of action potential generation (Vthr). We have shown recently that conventional invasive recording techniques provide an erroneous estimation of these parameters in immature neurons. In this study, we used noninvasive single N-methyl-d-aspartate and GABA channel recordings in rodent brain slices to measure both Em and E(GABA) in the same neuron. We show that GABA strongly depolarizes pyramidal neurons and interneurons in both deep and superficial layers of the immature neocortex (P2-P10). However, GABA generates action potentials in layer 5/6 (L5/6) but not L2/3 pyramidal cells, since L5/6 pyramidal cells have more depolarized resting potentials and more hyperpolarized Vthr. The excitatory GABA transiently drives oscillations generated by L5/6 pyramidal cells and interneurons during development (P5-P12). The NKCC1 co-transporter antagonist bumetanide strongly reduces [Cl(-)]i, GABA-induced depolarization, and network oscillations, confirming the importance of GABA signaling. Thus a strong GABA excitatory drive coupled with high intrinsic excitability of L5/6 pyramidal neurons and interneurons provide a powerful mechanism of synapse-driven oscillatory activity in the rodent neocortex in vitro. In the companion paper, we show that the excitatory GABA drives layer-specific seizures in the immature neocortex.

  14. Traveling wave front solutions in lateral-excitatory neuronal networks

    Directory of Open Access Journals (Sweden)

    Sittipong Ruktamatakul

    2008-05-01

    Full Text Available In this paper, we discuss the shape of traveling wave front solutions to a neuronal model with the connection function to be of lateral excitation type. This means that close connecting cells have an inhibitory influence, while cells that aremore distant have an excitatory influence. We give results on the shape of the wave fronts solutions, which exhibit different shapes depend ing on the size of a threshold parameter.

  15. Raphe magnus and reticulospinal actions on primary afferent depolarization of group I muscle afferents in the cat.

    Science.gov (United States)

    Quevedo, J; Eguibar, J R; Jiménez, I; Rudomin, P

    1995-02-01

    1. In the anaesthetized cat, electrical stimulation of the bulbar reticular formation produced a short latency (2.1 +/- 0.3 ms) positive potential in the cord dorsum. In contrast, stimulation of the nucleus raphe magnus with strengths below 50 microA evoked a slow negative potential with a mean latency of 5.5 +/- 0.6 ms that persisted after sectioning the contralateral pyramid and was abolished by sectioning the ipsilateral dorsolateral funiculus. 2. The field potentials evoked by stimulation of the bulbar reticular formation and of the nucleus raphe magnus had a different intraspinal distribution, suggesting activation of different sets of segmental interneurones. 3. Stimulation of these two supraspinal nuclei produced primary afferent depolarization (PAD) in single Ib fibres and inhibited the PAD elicited by group I volleys in single Ia fibres. The inhibition of the PAD of Ia fibres produced by reticulospinal and raphespinal inputs appears to be exerted on different interneurones along the PAD pathway. 4. It is concluded that, although reticulospinal and raphespinal pathways have similar inhibitory effects on PAD of Ia fibres, and similar excitatory effects on the PAD of Ib fibres, their actions are conveyed by partly independent pathways. This would allow their separate involvement in the control of posture and movement.

  16. Twin Supernova Studies with SNe Ia from SNfactory

    Science.gov (United States)

    Fakhouri, Hannah; Aldering, G.; Aragon, C.; Hsiao, E.; Loken, S.; Nugent, P.; Perlmutter, S.; Runge, K.; Thomas, R. C.; Antilogous, P.; Bongard, S.; Canto, A.; Pain, R.; Wu, C.; Chotard, N.; Copin, Y.; Gangler, E.; Pereira, R.; Smadja, G.; Pecontal, E.; Baltay, C.; Rabinowitz, D.; Scalzo, R.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K.; Tao, C.

    2011-01-01

    We present a study of twin supernovae with spectrophotometric timeseries of nearby Type Ia supernova from the Nearby Supernova Factory (Aldering, et al. 2002). One advantage of "twins” is they offer the best opportunity for having objects with the same intrinsic luminosities and colors, ostensibly leaving only extrinsic factors such as dust to explain any observed differences in brightness and color. Using well-sampled timeseries data for over 100 nearby Hubble-flow SNe Ia, we study the impact of dust on the brightness differences of SN Ia twins in order to improve the standardization of these standardizable candles that have been and will continue to be a primary tool in the determination of cosmological parameters. Specifically we are able to solve for the relative extinction and RV needed to bring the twins into near-perfect agreement. We will present a study of the resulting distribution of RV. In searching for twin supernovae we have found groups of SNe, again differing only by a dust law that accounts for the brightness differences. These groups allow us to look for similarities in subsets of SNe and explore spectrophotometric differences from group to group.

  17. Location-dependent excitatory synaptic interactions in pyramidal neuron dendrites.

    Directory of Open Access Journals (Sweden)

    Bardia F Behabadi

    Full Text Available Neocortical pyramidal neurons (PNs receive thousands of excitatory synaptic contacts on their basal dendrites. Some act as classical driver inputs while others are thought to modulate PN responses based on sensory or behavioral context, but the biophysical mechanisms that mediate classical-contextual interactions in these dendrites remain poorly understood. We hypothesized that if two excitatory pathways bias their synaptic projections towards proximal vs. distal ends of the basal branches, the very different local spike thresholds and attenuation factors for inputs near and far from the soma might provide the basis for a classical-contextual functional asymmetry. Supporting this possibility, we found both in compartmental models and electrophysiological recordings in brain slices that the responses of basal dendrites to spatially separated inputs are indeed strongly asymmetric. Distal excitation lowers the local spike threshold for more proximal inputs, while having little effect on peak responses at the soma. In contrast, proximal excitation lowers the threshold, but also substantially increases the gain of distally-driven responses. Our findings support the view that PN basal dendrites possess significant analog computing capabilities, and suggest that the diverse forms of nonlinear response modulation seen in the neocortex, including uni-modal, cross-modal, and attentional effects, could depend in part on pathway-specific biases in the spatial distribution of excitatory synaptic contacts onto PN basal dendritic arbors.

  18. Delayed excitatory and inhibitory feedback shape neural information transmission

    Science.gov (United States)

    Chacron, Maurice J.; Longtin, André; Maler, Leonard

    2017-01-01

    Feedback circuitry with conduction and synaptic delays is ubiquitous in the nervous system. Yet the effects of delayed feedback on sensory processing of natural signals are poorly understood. This study explores the consequences of delayed excitatory and inhibitory feedback inputs on the processing of sensory information. We show, through numerical simulations and theory, that excitatory and inhibitory feedback can alter the firing frequency response of stochastic neurons in opposite ways by creating dynamical resonances, which in turn lead to information resonances (i.e., increased information transfer for specific ranges of input frequencies). The resonances are created at the expense of decreased information transfer in other frequency ranges. Using linear response theory for stochastically firing neurons, we explain how feedback signals shape the neural transfer function for a single neuron as a function of network size. We also find that balanced excitatory and inhibitory feedback can further enhance information tuning while maintaining a constant mean firing rate. Finally, we apply this theory to in vivo experimental data from weakly electric fish in which the feedback loop can be opened. We show that it qualitatively predicts the observed effects of inhibitory feedback. Our study of feedback excitation and inhibition reveals a possible mechanism by which optimal processing may be achieved over selected frequency ranges. PMID:16383655

  19. Shape perception enhances perceived contrast: evidence for excitatory predictive feedback?

    Science.gov (United States)

    Han, Biao; VanRullen, Rufin

    2016-03-14

    Predictive coding theory suggests that predictable responses are "explained away" (i.e., reduced) by feedback. Experimental evidence for feedback inhibition, however, is inconsistent: most neuroimaging studies show reduced activity by predictive feedback, while neurophysiology indicates that most inter-areal cortical feedback is excitatory and targets excitatory neurons. In this study, we asked subjects to judge the luminance of two gray disks containing stimulus outlines: one enabling predictive feedback (a 3D-shape) and one impeding it (random-lines). These outlines were comparable to those used in past neuroimaging studies. All 14 subjects consistently perceived the disk with a 3D-shape stimulus brighter; thus, predictive feedback enhanced perceived contrast. Since early visual cortex activity at the population level has been shown to have a monotonic relationship with subjective contrast perception, we speculate that the perceived contrast enhancement could reflect an increase in neuronal activity. In other words, predictive feedback may have had an excitatory influence on neuronal responses. Control experiments ruled out attention bias, local feature differences and response bias as alternate explanations.

  20. The progenitors of supernovae Type Ia

    Science.gov (United States)

    Toonen, Silvia

    2014-09-01

    Despite the significance of Type Ia supernovae (SNeIa) in many fields in astrophysics, SNeIa lack a theoretical explanation. SNeIa are generally thought to be thermonuclear explosions of carbon/oxygen (CO) white dwarfs (WDs). The canonical scenarios involve white dwarfs reaching the Chandrasekhar mass, either by accretion from a non-degenerate companion (single-degenerate channel, SD) or by a merger of two CO WDs (double-degenerate channel, DD). The study of SNeIa progenitors is a very active field of research for binary population synthesis (BPS) studies. The strength of the BPS approach is to study the effect of uncertainties in binary evolution on the macroscopic properties of a binary population, in order to constrain binary evolutionary processes. I will discuss the expected SNeIa rate from the BPS approach and the uncertainties in their progenitor evolution, and compare with current observations. I will also discuss the results of the POPCORN project in which four BPS codes were compared to better understand the differences in the predicted SNeIa rate of the SD channel. The goal of this project is to investigate whether differences in the simulated populations are due to numerical effects or whether they can be explained by differences in the input physics. I will show which assumptions in BPS codes affect the results most and hence should be studied in more detail.

  1. Ultraviolet Diversity of Type Ia Supernovae

    CERN Document Server

    Foley, Ryan J; Brown, P; Filippenko, A V; Fox, O D; Hillebrandt, W; Kirshner, R P; Marion, G H; Milne, P A; Parrent, J T; Pignata, G; Stritzinger, M D

    2016-01-01

    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 A. We focus on spectra taken within 5 days of maximum brightness. Our sample of ten SNe Ia spans the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 A (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe I...

  2. Constraining cosmological parameter with SN Ia

    Science.gov (United States)

    Indra Putri, A. N.; Wulandari, H. R. Tri

    2016-11-01

    A type I supemovae (SN Ia) is an exploding white dwarf, whose mass exceeds Chandrasekar limit (1.44 solar mass). If a white dwarf is in a binary system, it may accrete matter from the companion, resulting in an excess mass that cannot be balanced by the pressure of degenerated electrons in the core. SNe Ia are highly luminous objects, that they are visible from very high distances. After some corrections (stretch (s), colour (c), K-corrections, etc.), the variations in the light curves of SNe Ia can be suppressed to be no more than 10%. Their high luminosity and almost uniform intrinsic brightness at the peak light, i.e. MB ∼ -19, make SNe Ia ideal standard candle. Because of their visibility from large distances, SNe Ia can be employed as a cosmological measuring tool. It was analysis of SNe Ia data that indicated for the first time, that the universe is not only expanding, but also accelerating. This work analyzed a compilation of SNe Ia data to determine several cosmological parameters (H0, Ωm, Ωa, and w). It can be concluded from the analysis, that our universe is a flat, dark energy dominated universe, and that the cosmological constant A is a suitable candidate for dark energy.

  3. Luminosity distributions of Type Ia Supernovae

    CERN Document Server

    Ashall, Chris; Sasdelli, Michele; Prentice, Simon

    2016-01-01

    We have assembled a dataset of 165 low redshift, $z<$0.06, publicly available type Ia supernovae (SNe Ia). We produce maximum light magnitude ($M_{B}$ and $M_{V}$) distributions of SNe Ia to explore the diversity of parameter space that they can fill. Before correction for host galaxy extinction we find that the mean $M_{B}$ and $M_{V}$ of SNe Ia are $-18.58\\pm0.07$mag and $-18.72\\pm0.05$mag respectively. Host galaxy extinction is corrected using a new method based on the SN spectrum. After correction, the mean values of $M_{B}$ and $M_{V}$ of SNe Ia are $-19.10\\pm0.06$ and $-19.10\\pm0.05$mag respectively. After correction for host galaxy extinction, `normal' SNeIa ($\\Delta m_{15}(B)<1.6$mag) fill a larger parameter space in the Width-Luminosity Relation (WLR) than previously suggested, and there is evidence for luminous SNe Ia with large $\\Delta m_{15}(B)$. We find a bimodal distribution in $\\Delta m_{15}(B)$, with a pronounced lack of transitional events at $\\Delta m_{15}(B)$=1.6 mag. We confirm that ...

  4. Infrared Light Curves of Type Ia Supernovae

    Science.gov (United States)

    Friedman, Andrew Samuel

    2012-05-01

    This thesis presents the CfAIR2 data set, which includes over 4000 near-Infrared (NIR) JHK8-band measurements of 104 Type Ia Supernovae (SN Ia) observed from 2005-2011 using PAIRITEL, the 1.3-m Peters Automated InfraRed Imaging TELescope at the Fred Lawrence Whipple Observatory (FLWO) on Mount Hopkins, Arizona. While the discovery of dark energy and most subsequent supernova cosmology has been performed using optical and Ultraviolet wavelength observations of SN Ia, a growing body of evidence suggests that NIR SN Ia observations will be crucial for future cosmological studies. Whereas SN Ia observed at optical wavelengths have been shown to be excellent standardizeable candles, using empirical correlations between luminosity, light curve shape, and color, the CfAIR2 data set strengthens the evidence that SN Ia at NIR wavelengths are essentially standard candles, even without correction for light-curve shape or for reddening. CfAIR2 was obtained as part of the CfA Supernova Program, an ongoing multi-wavelength follow-up effort at FLWO designed to observe high-quality, densely sampled light curves and spectra of hundreds of low-redshift SN Ia. CfAIR2 is the largest homogeneously observed and processed NIR data set of its kind to date, nearly tripling the number of individual JHK8-band observations and nearly doubling the set of SN Ia with published NIR light curves in the literature. Matched only by the recently published Carnegie Supernova Project sample, CfAIR2 complements the large and growing set of low-redshift optical and NIR SN Ia observations obtained by the CfA and other programs, making this data set a unique and particularly valuable local universe anchor for future supernova cosmology.

  5. 22nd IAS Meeting of Sedimentology

    Institute of Scientific and Technical Information of China (English)

    DavorPavelic; IgorVlahovic; JosipHalamic

    2004-01-01

    The 22nd IAS Meeting of Sedimentology was held in the Convention Centre of the Grand Hotel Adriatic, in a small touristic town Opatija, located on the eastern Adriatic coast where Central Europe and the Mediterranean meet. It was the second IAS Meeting held in Croatia--the first one, 4th IAS Regional Meeting of Sedimentology, was held in Split in 1983. The Meeting in Opatija was organized by the Institute of Geology (Zagreb) and the Croatian Geological Society. The sponsor was Ministry of Science and Technology of the Reoublic of Croatia.

  6. SNe Ia as a cosmological probe

    CERN Document Server

    Meng, Xiangcun; Han, Zhanwen

    2015-01-01

    Type Ia supernovae luminosities can be corrected to render them useful as standard candles able to probe the expansion history of the universe. This technique was successful applied to discover the present acceleration of the universe. As the number of SNe Ia observed at high redshift increases and analysis techniques are perfected, people aim to use this technique to probe the equation of state of the dark energy. Nevertheless, the nature of SNe Ia progenitors remains controversial and concerns persist about possible evolution effects that may be larger and harder to characterize than the more obvious statistical uncertainties.

  7. Bioengineered human IAS reconstructs with functional and molecular properties similar to intact IAS

    OpenAIRE

    Singh, Jagmohan; Rattan, Satish

    2012-01-01

    Because of its critical importance in rectoanal incontinence, we determined the feasibility to reconstruct internal anal sphincter (IAS) from human IAS smooth muscle cells (SMCs) with functional and molecular attributes similar to the intact sphincter. The reconstructs were developed using SMCs from the circular smooth muscle layer of the human IAS, grown in smooth muscle differentiation media under sterile conditions in Sylgard-coated tissue culture plates with central Sylgard posts. The bas...

  8. A review of type Ia supernova spectra

    CERN Document Server

    Parrent, J; Parthasarathy, M

    2014-01-01

    SN 2011fe was the nearest and best-observed type Ia supernova in a generation, and brought previous incomplete datasets into sharp contrast with the detailed new data. In retrospect, documenting spectroscopic behaviors of type Ia supernovae has been more often limited by sparse and incomplete temporal sampling than by consequences of signal-to-noise ratios, telluric features, or small sample sizes. As a result, type Ia supernovae have been primarily studied insofar as parameters discretized by relative epochs and incomplete temporal snapshots near maximum light. Here we discuss a necessary next step toward consistently modeling and directly measuring spectroscopic observables of type Ia supernova spectra. In addition, we analyze current spectroscopic data in the parameter space defined by empirical metrics, which will be relevant even after progenitors are observed and detailed models are refined.

  9. Improvements to type Ia supernova models

    Science.gov (United States)

    Saunders, Clare M.

    Type Ia Supernovae provided the first strong evidence of dark energy and are still an important tool for measuring the accelerated expansion of the universe. However, future improvements will be limited by systematic uncertainties in our use of Type Ia supernovae as standard candles. Using Type Ia supernovae for cosmology relies on our ability to standardize their absolute magnitudes, but this relies on imperfect models of supernova spectra time series. This thesis is focused on using data from the Nearby Supernova Factory both to understand current sources of uncertainty in standardizing Type Ia supernovae and to develop techniques that can be used to limit uncertainty in future analyses. (Abstract shortened by ProQuest.).

  10. Differential effects of (-)-baclofen on Ia and descending monosynaptic EPSPs.

    Science.gov (United States)

    Jiménez, I; Rudomin, P; Enriquez, M

    1991-01-01

    1. In cats anesthetized with alpha-chloralose, population synaptic responses of motoneurons produced by stimulation of group I afferents were recorded from ventral roots with a sucrose gap or extracellularly from the motor pool. These responses were depressed, and often abolished, following the intravenous injection of 1-3 mg/kg of (-)-baclofen, a presumed GABAb agonist. 2. The monosynaptic population responses of motoneurons produced by stimulation of the ipsilateral ventromedial funiculus (VMF), the bulbar reticular formation or the vestibular nucleus, were also depressed following the administration of (-)-baclofen, but to a lesser degree than responses produced by stimulation of group I fibers. 3. Depression of the synaptic actions of Ia and of descending fibers following the administration of (-)-baclofen occurred without significant changes in the presynaptic volley recorded from the cord dorsum. However, in 3/4 experiments the intraspinally recorded Ia terminal potential was reduced following the injection of (-)-baclofen. The VMF terminal potentials were also depressed, but to a lesser degree. 4. Intracellular recordings from spinal motoneurons indicate that the (-)-baclofen-induced depression of the monosynaptic Ia- and VMF-EPSPs occurred without important changes in the time course of EPSP decay. This suggests that with the amounts used, postsynaptic changes were not contributing significantly to the EPSP depression. 5. It is suggested that (-)-baclofen depresses synaptic transmission probably by activation of GABAb receptors located at the intraspinal terminations of Ia and descending fibers. The lower sensitivity of VMF actions to (-)-baclofen would be accounted for by a relatively low density of baclofen receptors in descending fiber terminals.

  11. Close binary white dwarfs and supernovae IA

    Directory of Open Access Journals (Sweden)

    R. Napiwotzki

    2004-01-01

    Full Text Available Informamos sobre el estado actual de los \\surveys" de velocidades radiales para binarias de enanas blancas (degeneradas dobles - DDs incluyendo SPY (Exploraci on ESO de progenitoras de supernovas Ia que recien- temente se llevaron a cabo en el VLT. Una amplia muestra de DDs nos permitir a poner fuertes restricciones sobre las fases evolutivas de los sistemas progenitores de binarias cercanas y tambi en llevar a cabo pruebas observacionales del escenario DD para supernovas de tipo Ia.

  12. Ligands targeting the excitatory amino acid transporters (EAATs).

    Science.gov (United States)

    Dunlop, John; Butera, John A

    2006-01-01

    This review provides an overview of ligands for the excitatory amino acid transporters (EAATs), a family of high-affinity glutamate transporters localized to the plasma membrane of neurons and astroglial cells. Ligand development from the perspective of identifying novel and more selective tools for elucidating transporter subtype function, and the potential of transporter ligands in a therapeutic setting are discussed. Acute pharmacological modulation of EAAT activity in the form of linear and conformationally restricted glutamate and aspartate analogs is presented, in addition to recent strategies aimed more toward modulating transporter expression levels, the latter of particular significance to the development of transporter based therapeutics.

  13. A Role for Excitatory Amino Acids in Diabetic Eye Disease

    Science.gov (United States)

    Pulido, Jose E.; Pulido, Jose S.; Erie, Jay C.; Arroyo, Jorge; Bertram, Kurt; Lu, Miao-Jen; Shippy, Scott A.

    2007-01-01

    Diabetic retinopathy is a leading cause of vision loss. The primary clinical hallmarks are vascular changes that appear to contribute to the loss of sight. In a number of neurodegenerative disorders there is an appreciation that increased levels of excitatory amino acids are excitotoxic. The primary amino acid responsible appears to be the neurotransmitter glutamate. This review examines the nature of glutamatergic signaling at the retina and the growing evidence from clinical and animal model studies that glutamate may be playing similar excitotoxic roles at the diabetic retina. PMID:17713594

  14. A Role for Excitatory Amino Acids in Diabetic Eye Disease

    Directory of Open Access Journals (Sweden)

    Jose E. Pulido

    2007-01-01

    Full Text Available Diabetic retinopathy is a leading cause of vision loss. The primary clinical hallmarks are vascular changes that appear to contribute to the loss of sight. In a number of neurodegenerative disorders there is an appreciation that increased levels of excitatory amino acids are excitotoxic. The primary amino acid responsible appears to be the neurotransmitter glutamate. This review examines the nature of glutamatergic signaling at the retina and the growing evidence from clinical and animal model studies that glutamate may be playing similar excitotoxic roles at the diabetic retina.

  15. Type Ia Supernovae: Colors, Rates, and Progenitors

    CERN Document Server

    Heringer, Epson; Kezwer, Jason; Graham, Melissa L; Sand, David; Bildfell, Chris

    2016-01-01

    The rate of type Ia supernovae (SNe Ia) in a galaxy depends not only on stellar mass, but also on star formation history. Here we show that two simple observational quantities ($g-r$ or $u-r$ host galaxy color, and $r$-band luminosity), coupled with an assumed delay time distribution (the rate of SNe Ia as a function of time for an instantaneous burst of star formation), are sufficient to accurately determine a galaxy's SN Ia rate, with very little sensitivity to the precise details of the star formation history. Using this result, we compare observed and predicted color distributions of SN Ia hosts for the MENeaCS cluster supernova survey, and for the SDSS Stripe 82 supernova survey. The observations are consistent with a continuous delay time distribution (DTD), without any cutoff. For old progenitor systems the power-law slope for the DTD is found to be $-1.50 ^{+0.19} _{-0.15}$. This result favours the double degenerate scenario for SN Ia, though other interpretations are possible. We find that the late-t...

  16. Alteration of Excitatory Amino Acid in Experimental Spinal Cord Injury in Rats

    Institute of Scientific and Technical Information of China (English)

    张宁; 罗永湘

    2002-01-01

    Objective To detect the effect of excitatory amino acid (EAA) in the sec-ondary damage following spinal cord injury (SCI). Methods Glutamate (Glu) and Aspartate(Asp) on the injury site (T8) were studied using a rat SCI model induced by Allen's weight drop method(10g×2.5cm). The result suggested that Asp and Glu were significantly increased in 10 min. Re-sults Glu was significantly decreased from 2 h to 24 h,while Asp was a little reduced in 2 h,andslightly rose in 4 h as compared with Control Group. Though elevated in 8 h, it dropped again in 24 h ascompared with Control Group. Conclusion The result indicates that the rise of EAA following SCIcould be the cause of the secondary spinal cord damage.

  17. Circulation of Tc Ia discrete type unit Trypanosoma cruzi in Yucatan Mexico.

    Science.gov (United States)

    Monteón, Victor; Triana-Chávez, Omar; Mejía-Jaramillo, Ana; Pennignton, Pamela; Ramos-Ligonio, Ángel; Acosta, Karla; Lopez, Ruth

    2016-06-01

    The etiologic agent Trypanosoma cruzi (Tc) has been grouped into six discrete type units (DTU I-VI); within DTU-I exists four subgroups defined Ia-Id. In Colombia, the genotype Ia is associated with human infection and domiciliated Rhodnius vector. In the Yucatan Peninsula of Mexico, the main vector involved in T. cruzi transmission is Triatoma dimidiata predominantly via sylvatic and peridomiciliated cycles. In this study, multiple sequence analysis of mini-exon intergenic regions of T. cruzi isolates obtained from T. dimidiata in the Yucatan Peninsula of Mexico revealed they belonged to Tc Ia DTU along with two additional Mexican strains located 1,570 km away from Yucatan. In conclusion Tc Ia circulates in the Yucatan peninsula in T. dimidiata vector and likewise in the northwest region of Mexico.

  18. Summation of excitatory postsynaptic potentials in electrically-coupled neurones.

    Science.gov (United States)

    Vazquez, Y; Mendez, B; Trueta, C; De-Miguel, F F

    2009-09-29

    Dendritic electrical coupling increases the number of effective synaptic inputs onto neurones by allowing the direct spread of synaptic potentials from one neurone to another. Here we studied the summation of excitatory postsynaptic potentials (EPSPs) produced locally and arriving from the coupled neurone (transjunctional) in pairs of electrically-coupled Retzius neurones of the leech. We combined paired recordings of EPSPs, the production of artificial excitatory postsynaptic potentials (APSPs) in neurone pairs with different coupling coefficients and simulations of EPSPs produced in the coupled dendrites. Summation of the EPSPs produced in the dendrites was always linear, suggesting that synchronous EPSPs are produced at two or more different pairs of coupled dendrites and not in both sides of any one gap junction. The different spatio-temporal relationships explored between pairs of EPSPs or APSPs produced three main effects. (1) Synchronous pairs of EPSPs or APSPs exhibited an elongation of their decay phase compared to single EPSPs. (2) Asymmetries in the amplitudes between the pair of EPSPs added a "hump" to the smallest EPSP. (3) Modelling the inputs near the electrical synapse or anticipating the production of the transjunctional APSP increased the amplitude of the compound EPSP. The magnitude of all these changes depended on the coupling coefficient of the neurones. We also show that the hump improves the passive conduction of EPSPs by adding low frequency components. The diverse effects of summation of local and alien EPSPs shown here endow electrically-coupled neurones with a wider repertoire of adjustable integrative possibilities.

  19. Axonal dynamics of excitatory and inhibitory neurons in somatosensory cortex.

    Directory of Open Access Journals (Sweden)

    Sally A Marik

    Full Text Available Cortical topography can be remapped as a consequence of sensory deprivation, suggesting that cortical circuits are continually modified by experience. To see the effect of altered sensory experience on specific components of cortical circuits, we imaged neurons, labeled with a genetically modified adeno-associated virus, in the intact mouse somatosensory cortex before and after whisker plucking. Following whisker plucking we observed massive and rapid reorganization of the axons of both excitatory and inhibitory neurons, accompanied by a transient increase in bouton density. For horizontally projecting axons of excitatory neurons there was a net increase in axonal projections from the non-deprived whisker barrel columns into the deprived barrel columns. The axon collaterals of inhibitory neurons located in the deprived whisker barrel columns retracted in the vicinity of their somata and sprouted long-range projections beyond their normal reach towards the non-deprived whisker barrel columns. These results suggest that alterations in the balance of excitation and inhibition in deprived and non-deprived barrel columns underlie the topographic remapping associated with sensory deprivation.

  20. SN 2002cx The Most Peculiar Known Type Ia Supernova

    CERN Document Server

    Li, W; Chornock, R; Berger, E; Berlind, P; Calkins, M L; Challis, P M; Fassnacht, C D; Jha, S; Kirshner, R P; Matheson, T; Sargent, W L W; Simcoe, R A; Smith, G H; Squires, G; Li, Weidong; Filippenko, Alexei V.; Chornock, Ryan; Berger, Edo; Berlind, Perry; Calkins, Michael L.; Challis, Peter; Fassnacht, Chris; Jha, Saurabh; Kirshner, Robert P.; Matheson, Thomas; Sargent, Wallace L. W.; Simcoe, Robert A.; Smith, Graeme H.; Squires, Gordon

    2003-01-01

    We present photometric and spectroscopic observations of supernova (SN) 2002cx, which reveal it to be unique among all observed type Ia supernovae (SNe Ia). SN 2002cx exhibits a SN 1991T-like premaximum spectrum, a SN 1991bg-like luminosity, and expansion velocities roughly half those of normal SNe Ia. Photometrically, SN 2002cx has a broad peak in the $R$ band and a plateau phase in the $I$ band, and slow late-time decline. The $(B - V)$ color evolution is nearly normal, but the $(V - R)$ and $(V - I)$ colors are very red. Early-time spectra of SN 2002cx evolve very quickly and are dominated by lines from Fe-group elements; features from intermediate-mass elements (Ca, S, Si) are weak or absent. Mysterious emission lines are observed around 7000 \\AA\\ at about 3 weeks after maximum brightness. The nebular spectrum of SN 2002cx is also unique, consisting of narrow iron and cobalt lines. The observations of SN 2002cx are inconsistent with the observed spectral/photometric sequence, and provide a major challenge...

  1. Selections from 2015: Two Kinds of Type Ia Supernovae

    Science.gov (United States)

    Kohler, Susanna

    2015-03-01

    Editors Note:In these last two weeks of 2015, well be looking at a few selections from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.The Changing Fractions of Type Ia Supernova NUVOptical Subclasses with RedshiftPublished April2015Main takeaway:A team of scientists led by Peter Milne (University of Arizona) used ultraviolet observations from the Swift spacecraft to determine that type Ia supernovae, stellar explosions previously thought to all belong in the same class, actually fall into two subgroups: those that are slightly redder in NUV wavelengths and those that are slightly bluer.Plot of the percentage of supernovae that are NUV-blue (rather than NUV-red), as a function of redshift. NUV-blue supernovae dominate at higher redshifts. [Milne et al. 2015]Why its interesting:It turns out that the fraction of supernovae in each of these two groups is redshift-dependent. At low redshifts (i.e., nearby), the population of type Ia supernovae is dominated by NUV-red supernovae. At high redshifts (i.e., far away), the population is dominated by NUV-blue supernovae. Since cosmological distances are measured using Type Ia supernovae as standard candles, the fact that weve been modeling these supernovae all the same way (rather than treating them as two separate subclasses) means we may have been systematically misinterpreting distances.What this means for the universes expansion:This seemingly simple discovery carries hefty repercussions in fact, our estimates of the expansion rate of the universe may be incorrect! The authors believe that if we correct for this error, well find that the universe is not expanding as quickly as we thought.CitationPeter A. Milne et al 2015 ApJ 803 20. doi:10.1088/0004-637X/803/1/20

  2. Merging white dwarfs and Type Ia supernovae

    Science.gov (United States)

    Yungelson, L. R.; Kuranov, A. G.

    2017-01-01

    Using population synthesis, we study a double-degenerate (DD) scenario for Type Ia supernovae (SNe Ia), aiming to estimate the maximum possible contribution to the rate of SNe from this scenario and the dependence of the delay-time distribution (DTD) on it. We make an extreme assumption that all mergers of super-Chandrasekhar pairs of CO white dwarfs (WDs) and mergers of CO WDs more massive than 0.47 M⊙ with hybrid or helium WDs more massive than 0.37 M⊙ produce SNe Ia. The models are parametrized by the product of the common envelope efficiency and the parameter of binding energy of stellar envelopes, αce λ, which we vary between 0.25 and 2. The best agreement with observations is obtained for αce λ = 2. A substantial contribution to the rate of SNe Ia is provided by the pairs with a hybrid WD. The estimated Galactic rate of SNe Ia is 6.5 × 10-3 yr-1 (for the mass of the bulge and thin disc equal to 7.2 × 1010 M⊙), which is comparable to the observational estimate (5.4 ± 0.12) × 10-3 yr-1. The model DTD for 1 ≤ t ≤ 8 Gyr satisfactorily fits the DTD for SNe Ia in the field galaxies (Maoz, Mannucci & Brandt). For this epoch, the model DTD is ∝t-1.64. At earlier and later epochs, our DTD has a deficit of events, as in other studies. Marginal agreement with the observational DTD is achieved even if only CO+CO WDs with M1 ≥ 0.8 M⊙ and M2 ≥ 0.6 M⊙ produce SNe Ia. A better agreement of observed and modelled DTD may be obtained if tidal effects are weaker than assumed and/or the metallicity of the population is much lower than solar.

  3. mGluRs modulate strength and timing of excitatory transmission in hippocampal area CA3.

    Science.gov (United States)

    Cosgrove, Kathleen E; Galván, Emilio J; Barrionuevo, Germán; Meriney, Stephen D

    2011-08-01

    Excitatory transmission within hippocampal area CA3 stems from three major glutamatergic pathways: the perforant path formed by axons of layer II stellate cells in the entorhinal cortex, the mossy fiber axons originating from the dentate gyrus granule cells, and the recurrent axon collaterals of CA3 pyramidal cells. The synaptic communication of each of these pathways is modulated by metabotropic glutamate receptors that fine-tune the signal by affecting both the timing and strength of the connection. Within area CA3 of the hippocampus, group I mGluRs (mGluR1 and mGluR5) are expressed postsynaptically, whereas group II (mGluR2 and mGluR3) and III mGluRs (mGluR4, mGluR7, and mGluR8) are expressed presynaptically. Receptors from each group have been demonstrated to be required for different forms of pre- and postsynaptic long-term plasticity and also have been implicated in regulating short-term plasticity. A recent observation has demonstrated that a presynaptically expressed mGluR can affect the timing of action potentials elicited in the postsynaptic target. Interestingly, mGluRs can be distributed in a target-specific manner, such that synaptic input from one presynaptic neuron can be modulated by different receptors at each of its postsynaptic targets. Consequently, mGluRs provide a mechanism for synaptic specialization of glutamatergic transmission in the hippocampus. This review will highlight the variability in mGluR modulation of excitatory transmission within area CA3 with an emphasis on how these receptors contribute to the strength and timing of network activity within pyramidal cells and interneurons.

  4. Structure and Function of APH(4)-Ia, a Hygromycin B Resistance Enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Stogios, Peter J.; Shakya, Tushar; Evdokimova, Elena; Savchenko, Alexei; Wright, Gerard D. (Toronto); (McMaster U.)

    2011-11-18

    The aminoglycoside phosphotransferase (APH) APH(4)-Ia is one of two enzymes responsible for bacterial resistance to the atypical aminoglycoside antibiotic hygromycin B (hygB). The crystal structure of APH(4)-Ia enzyme was solved in complex with hygB at 1.95 {angstrom} resolution. The APH(4)-Ia structure adapts a general two-lobe architecture shared by other APH enzymes and eukaryotic kinases, with the active site located at the interdomain cavity. The enzyme forms an extended hydrogen bond network with hygB primarily through polar and acidic side chain groups. Individual alanine substitutions of seven residues involved in hygB binding did not have significant effect on APH(4)-Ia enzymatic activity, indicating that the binding affinity is spread across a distributed network. hygB appeared as the only substrate recognized by APH(4)-Ia among the panel of 14 aminoglycoside compounds. Analysis of the active site architecture and the interaction with the hygB molecule demonstrated several unique features supporting such restricted substrate specificity. Primarily the APH(4)-Ia substrate-binding site contains a cluster of hydrophobic residues that provides a complementary surface to the twisted structure of the substrate. Similar to APH(2{double_prime}) enzymes, the APH(4)-Ia is able to utilize either ATP or GTP for phosphoryl transfer. The defined structural features of APH(4)-Ia interactions with hygB and the promiscuity in regard to ATP or GTP binding could be exploited for the design of novel aminoglycoside antibiotics or inhibitors of this enzyme.

  5. Type Ia Supernovae and the Hubble Constant

    CERN Document Server

    Branch, D

    1998-01-01

    The focus of this review is the work that has been done during the 1990s on using Type Ia supernovae (SNe Ia) to measure the Hubble constant ($H_0$). SNe Ia are well suited for measuring $H_0$. A straightforward maximum-light color criterion can weed out the minority of observed events that are either intrinsically subluminous or substantially extinguished by dust, leaving a majority subsample that has observational absolute-magnitude dispersions of less than $\\sigma_{obs}(M_B) \\simeq \\sigma_{obs}(M_V) \\simeq 0.3$ mag. Correlations between absolute magnitude and one or more distance-independent SN Ia or parent-galaxy observables can be used to further standardize the absolute magnitudes to better than 0.2 mag. The absolute magnitudes can be calibrated in two independent ways --- empirically, using Cepheid-based distances to parent galaxies of SNe Ia, and physically, by light curve and spectrum fitting. At present the empirical and physical calibrations are in agreement at $M_B \\simeq M_V \\simeq -19.4$ or -19....

  6. The Spectroscopic Diversity of Type Ia Supernovae

    CERN Document Server

    Blondin, S; Kirshner, R P; Mandel, K S; Berlind, P; Calkins, M; Challis, P; Garnavich, P M; Jha, S W; Modjaz, M; Riess, A G; Schmidt, B P

    2012-01-01

    We present 2603 spectra of 462 nearby Type Ia supernovae (SN Ia) obtained during 1993-2008 through the Center for Astrophysics Supernova Program. Most of the spectra were obtained with the FAST spectrograph at the FLWO 1.5m telescope and reduced in a consistent manner, making data set well suited for studies of SN Ia spectroscopic diversity. We study the spectroscopic and photometric properties of SN Ia as a function of spectroscopic class using the classification schemes of Branch et al. and Wang et al. The width-luminosity relation appears to be steeper for SN Ia with broader lines. Based on the evolution of the characteristic Si II 6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ~0 to ~400 km/s/day considering the instantaneous velocity decline rate at maximum light. We find a weaker and less significant correlation between Si II velocity and intrinsic B-V color at maximum light than reported by Foley et al., owing to a more ...

  7. The GABA excitatory/inhibitory developmental sequence: a personal journey.

    Science.gov (United States)

    Ben-Ari, Y

    2014-10-24

    The developing brain is talkative but its language is not that of the adult. Most if not all voltage and transmitter-gated ionic currents follow a developmental sequence and network-driven patterns differ in immature and adult brains. This is best illustrated in studies engaged almost three decades ago in which we observed elevated intracellular chloride (Cl(-))i levels and excitatory GABA early during development and a perinatal excitatory/inhibitory shift. This sequence is observed in a wide range of brain structures and animal species suggesting that it has been conserved throughout evolution. It is mediated primarily by a developmentally regulated expression of the NKCC1 and KCC2 chloride importer and exporter respectively. The GABAergic depolarization acts in synergy with N-methyl-d-aspartate (NMDA) receptor-mediated and voltage-gated calcium currents to enhance intracellular calcium exerting trophic effects on neuritic growth, migration and synapse formation. These sequences can be deviated in utero by genetic or environmental insults leading to a persistence of immature features in the adult brain. This "neuroarcheology" concept paves the way to novel therapeutic perspectives based on the use of drugs that block immature but not adult currents. This is illustrated notably with the return to immature high levels of chloride and excitatory actions of GABA observed in many pathological conditions. This is due to the fact that in the immature brain a down regulation of KCC2 and an up regulation of NKCC1 are seen. Here, I present a personal history of how an unexpected observation led to novel concepts in developmental neurobiology and putative treatments of autism and other developmental disorders. Being a personal account, this review is neither exhaustive nor provides an update of this topic with all the studies that have contributed to this evolution. We all rely on previous inventors to allow science to advance. Here, I present a personal summary of this

  8. Control by Preynaptic Correlation: a mechanism affecting information transmission from Ia fibers to motoneurons.

    Science.gov (United States)

    Rudomin, P; Burke, R E; Núñez, R; Madrid, J; Dutton, H

    1975-03-01

    1. In the unanesthetized spinal cord of the cat, simultaneous intracellular recordings were made from two motoneurons belonging to the gastronemius motor nucleus. 2. Supramaximal iterative stimulation of small branches of the gastrocnemius nerve produced monosynaptic EPSPs (Ia EPSPs) of varying amplitude superimposed on a fluctuating base line. 3. In most cases the variance of the motoneuron membrane potential was increased above base-line levels with a time course approximately matching the Ia EPSP. This suggests that Ia EPSP fluctuations are greater than can be accounted for by the base-line fluctuations alone. 4. For a given series of Ia EPSPs, the smaller responses in the series had about the same decay phase as the larger EPSPs, suggesting that most of the Ia EPSP fluctuations were not due to systematic changes in postsynaptic conductances produced by ongoing activity, but rather to a presynaptic mechanism. 5. Simultaneous recording from two motoneurons showed that base-line fluctuations were positively correlated. In most cases, however, there was an additional increased correlation above base-line levels resembling the time course of the Ia EPSPs, indicating positive correlation between EPSP fluctuations which is attributed to a presynaptic mechanism. 6. Conditioning volleys to group I muscle afferents or to low-threshold cutaneous afferents reduced the variance of the Ia EPSPs and also their correlation in motoneuron pairs, often without changing the mean Ia EPSPs. 7. It is concluded that, in the unanesthetized spinal cord, in addition to the random process which governs transmitter release intrinsic to a given synaptic terminal, there is another stochastic process affecting, in a correlated manner, transmitter release in large sets of Ia synaptic terminals. Most likely, the correlation in transmitter release is achieved by membrane potential fluctuations imposed on the Ia terminal arborizations by ongoing activity of the segmental mechanism mediating

  9. Permanent central synaptic disconnection of proprioceptors after nerve injury and regeneration. I. Loss of VGLUT1/IA synapses on motoneurons.

    Science.gov (United States)

    Alvarez, Francisco J; Titus-Mitchell, Haley E; Bullinger, Katie L; Kraszpulski, Michal; Nardelli, Paul; Cope, Timothy C

    2011-11-01

    Motor and sensory proprioceptive axons reinnervate muscles after peripheral nerve transections followed by microsurgical reattachment; nevertheless, motor coordination remains abnormal and stretch reflexes absent. We analyzed the possibility that permanent losses of central IA afferent synapses, as a consequence of peripheral nerve injury, are responsible for this deficit. VGLUT1 was used as a marker of proprioceptive synapses on rat motoneurons. After nerve injuries synapses are stripped from motoneurons, but while other excitatory and inhibitory inputs eventually recover, VGLUT1 synapses are permanently lost on the cell body (75-95% synaptic losses) and on the proximal 100 μm of dendrite (50% loss). Lost VGLUT1 synapses did not recover, even many months after muscle reinnervation. Interestingly, VGLUT1 density in more distal dendrites did not change. To investigate whether losses are due to VGLUT1 downregulation in injured IA afferents or to complete synaptic disassembly and regression of IA ventral projections, we studied the central trajectories and synaptic varicosities of axon collaterals from control and regenerated afferents with IA-like responses to stretch that were intracellularly filled with neurobiotin. VGLUT1 was present in all synaptic varicosities, identified with the synaptic marker SV2, of control and regenerated afferents. However, regenerated afferents lacked axon collaterals and synapses in lamina IX. In conjunction with the companion electrophysiological study [Bullinger KL, Nardelli P, Pinter MJ, Alvarez FJ, Cope TC. J Neurophysiol (August 10, 2011). doi:10.1152/jn.01097.2010], we conclude that peripheral nerve injuries cause a permanent retraction of IA afferent synaptic varicosities from lamina IX and disconnection with motoneurons that is not recovered after peripheral regeneration and reinnervation of muscle by sensory and motor axons.

  10. IAS 41 Agriculture: Fair Value Accounting

    Directory of Open Access Journals (Sweden)

    Viorel Lefter

    2007-05-01

    Full Text Available Issuing this standard that had to be applied for the first time for the financial statements started after 1.01.2003 meant a change of direction from two points of view: on one hand, through IAS 41 was issued for the first time an extensive standard typical for this sector and, on the other hand, for the first time were included in the income statement, independently from the sales transactions, incomes from variations of the fair value of an asset. Because of this last aspect, IAS 41 can be considered an important standard, because it represents the starting point of a consistent transition from the purchase cost principle towards a fair value accounting. IASC has dedicated to the thematic field of agriculture a specific standard, because this economic branch has a great importance for the developing countries. On the other hand, IAS 41 is also applied for the agricultural activities of the enterprises from other sectors.

  11. New approaches to SNe Ia progenitors

    CERN Document Server

    Ruiz-Lapuente, Pilar

    2014-01-01

    Although Type Ia supernovae (SNe Ia) are a major tool in cosmology and play a key role in the chemical evolution of galaxies, the nature of their progenitor systems (apart from the fact that they must be close binaries containing at least one white dwarf) remains largely unknown. In the last decade, considerable efforts have been made, both observationally and theoretically, to solve this problem. Observations have, however, revealed a previously unsuspected variety of events, ranging from very underluminous outbursts to clearly overluminous ones, and spanning a range well outside the peak luminosity--decline rate of the light curve relationship, used to make calibrated candles of the SNe Ia. On the theoretical side, new explosion scenarios, such as violent mergings of pairs of white dwarfs, have been explored. We review those recent developments, emphasizing the new observational findings, but also trying to tie them to the different scenarios and explosion mechanisms proposed thus far.

  12. Psychopathology of excitatory and compulsive aspects of vandalistic graffiti.

    Science.gov (United States)

    Pani, Roberto; Sagliaschi, Samanta

    2009-12-01

    In this paper were explored psychological themes underlying vandalistic graffiti by 162 Italian adolescents (154 boys, 8 girls; M age = 17.5 yr., SD = 2.3) who "felt hooked" on vandalistic graffiti and agreed to participate in an interview with a graffiti writer. Use of this interview could clarify the motivations which led these youths to write on walls, the meaning they give to that act, the emotions they feel as they write, and their perception of risks and excitement involved. Qualitative analysis of their responses suggested these adolescents present a marked excitatory-compulsive trait, report a sense of emptiness, boredom, loneliness, and a lack of internal points of reference, and adopt behaviors linked to a pressing need for immediate gratification.

  13. Optimal properties of analog perceptrons with excitatory weights.

    Directory of Open Access Journals (Sweden)

    Claudia Clopath

    Full Text Available The cerebellum is a brain structure which has been traditionally devoted to supervised learning. According to this theory, plasticity at the Parallel Fiber (PF to Purkinje Cell (PC synapses is guided by the Climbing fibers (CF, which encode an 'error signal'. Purkinje cells have thus been modeled as perceptrons, learning input/output binary associations. At maximal capacity, a perceptron with excitatory weights expresses a large fraction of zero-weight synapses, in agreement with experimental findings. However, numerous experiments indicate that the firing rate of Purkinje cells varies in an analog, not binary, manner. In this paper, we study the perceptron with analog inputs and outputs. We show that the optimal input has a sparse binary distribution, in good agreement with the burst firing of the Granule cells. In addition, we show that the weight distribution consists of a large fraction of silent synapses, as in previously studied binary perceptron models, and as seen experimentally.

  14. Structural and functional dynamics of Excitatory Amino Acid Transporters (EAAT

    Directory of Open Access Journals (Sweden)

    Thomas Rauen

    2014-09-01

    Full Text Available Glutamate transporters control the glutamate homeostasis in the central nervous system, and, thus, are not only crucial for physiological excitatory synaptic signaling, but also for the prevention of a large number of neurodegenerative diseases that are associated with excessive and prolonged presence of the neurotransmitter glutamate in the extracellular space. Until now, five subtypes of high-affinity glutamate transporters (excitatory amino acid transporters, EAATs 1–5 have been identified. These 5 high-affinity glutamate transporter subtypes belong to the solute carrier 1 (SLC1 family of transmembrane proteins: EAAT1/GLAST (SLC1A3, EAAT2/GLT1 (SLC1A2, EAAT3/EAAC1 (SLC1A1, EAAT4 (SLC1A6 and EAAT5 (SLC1A7. EAATs are secondary-active transporters, taking up glutamate into the cell against a substantial concentration gradient. The driving force for concentrative uptake is provided by the co-transport of Na+ ions and the counter-transport of one K+ in a step independent of the glutamate translocation step. Due to the electrogenicity of transport, the transmembrane potential can also act as driving force. Glutamate transporters are also able to run in reverse, resulting in glutamate release from cells. Due to these important physiological functions, glutamate transporter expression and, therefore, the transport rate, are tightly regulated. The EAAT protein family are structurally expected to be highly similar, however, these transporters show a functional diversity that ranges from high capacity glutamate uptake systems (EAATs 1–3 to receptor-like glutamate activated anion channels (EAATs 4–5. Here, we provide an update on most recent progress made on EAAT’s molecular transport mechanism, structure-function relationships, pharmacology, and will add recent insights into mechanism of rapid membrane trafficking of glutamate transporters.

  15. Tratamento das cefaléias Treatment of headaches

    Directory of Open Access Journals (Sweden)

    José Luiz Dias Gherpelli

    2002-08-01

    Full Text Available Objetivo: realizar revisão bibliográfica sobre o tema tratamento da cefaléia na infância e adolescência. Fontes dos dados: revisão bibliográfica através do banco de dados Medline, utilizando os termos: cefaléia, enxaqueca ou migrânea, infância ou adolescência e tratamento, no período de 1966 a 2001, excluindo artigos de revisão e registros de casos. Foram selecionados artigos científicos que relataram estudos sobre a eficácia da terapêutica farmacológica e não farmacológica no tratamento das cefaléias primárias. Síntese dos dados: foram encontrados 104 artigos científicos, sendo selecionados aqueles que relataram estudos do tipo caso-controle, ou droga versus placebo, cegos ou abertos, e que estudassem crianças ou adolescentes. Conclusões: é digna de nota a pobreza de estudos controlados sobre o tema na faixa etária pediátrica, apesar da importância que as cefaléias primárias apresentam na prática clínica. Apenas algumas drogas foram estudadas de forma cientificamente adequada e, mesmo assim, o número de estudos é pequeno. Tanto o tratamento da crise álgica aguda quanto a profilaxia da cefaléia foram abordados.Objective: to perform a bibliographic review about headache treatment in childhood and adolescence. Sources: articles were searched through Medline database using the terms: migraine, or headache, childhood, or adolescence, and treatment, during the period between 1966 and 2001. Review articles and case reports were excluded. Only articles dealing with pharmacological, and non-pharmacological treatment of primary headaches were selected. Summary of the findings: a total of 104 articles were found; only those reporting results of the case-control studies, or drug vs. placebo, either blind, or open, and that included children, or adolescents were selected. Conclusions: only a few controlled studies about the headache treatment were found in the pediatric age group, although primary headaches are

  16. Input-driven oscillations in networks with excitatory and inhibitory neurons with dynamic synapses.

    NARCIS (Netherlands)

    Marinazzo, D.; Kappen, H.J.; Gielen, S.C.A.M.

    2007-01-01

    Previous work has shown that networks of neurons with two coupled layers of excitatory and inhibitory neurons can reveal oscillatory activity. For example, Borgers and Kopell (2003) have shown that oscillations occur when the excitatory neurons receive a sufficiently large input. A constant drive to

  17. Bioengineered human IAS reconstructs with functional and molecular properties similar to intact IAS.

    Science.gov (United States)

    Singh, Jagmohan; Rattan, Satish

    2012-09-15

    Because of its critical importance in rectoanal incontinence, we determined the feasibility to reconstruct internal anal sphincter (IAS) from human IAS smooth muscle cells (SMCs) with functional and molecular attributes similar to the intact sphincter. The reconstructs were developed using SMCs from the circular smooth muscle layer of the human IAS, grown in smooth muscle differentiation media under sterile conditions in Sylgard-coated tissue culture plates with central Sylgard posts. The basal tone in the reconstructs and its changes were recorded following 0 Ca(2+), KCl, bethanechol, isoproterenol, protein kinase C (PKC) activator phorbol 12,13-dibutyrate, and Rho kinase (ROCK) and PKC inhibitors Y-27632 and Gö-6850, respectively. Western blot (WB), immunofluorescence (IF), and immunocytochemical (IC) analyses were also performed. The reconstructs developed spontaneous tone (0.68 ± 0.26 mN). Bethanechol (a muscarinic agonist) and K(+) depolarization produced contraction, whereas isoproterenol (β-adrenoceptor agonist) and Y-27632 produced a concentration-dependent decrease in the tone. Maximal decrease in basal tone with Y-27632 and Gö-6850 (each 10(-5) M) was 80.45 ± 3.29 and 17.76 ± 3.50%, respectively. WB data with the IAS constructs' SMCs revealed higher levels of RhoA/ROCK, protein kinase C-potentiated inhibitor or inhibitory phosphoprotein for myosin phosphatase (CPI-17), phospho-CPI-17, MYPT1, and 20-kDa myosin light chain vs. rectal smooth muscle. WB, IF, and IC studies of original SMCs and redispersed from the reconstructs for the relative distribution of different signal transduction proteins confirmed the feasibility of reconstruction of IAS with functional properties similar to intact IAS and demonstrated the development of myogenic tone with critical dependence on RhoA/ROCK. We conclude that it is feasible to bioengineer IAS constructs using human IAS SMCs that behave like intact IAS.

  18. EnviroAtlas - Woodbine, IA - Near Road Block Group Summary

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset addresses the tree buffer along heavily traveled roads. The roads are interstates, arterials, and collectors within the EnviroAtlas...

  19. Penerapan PSAK Adopsi IAS 41 Agriculture

    Directory of Open Access Journals (Sweden)

    Stefanus Ariyanto

    2014-05-01

    Full Text Available This study aims to determine whether the application of PSAK adopted from IAS 41: Agriculture should be applied to State-Owned Enterprises, especially the plantation SOE. So that the SOE financial information produced becomes more useful for decision-making. Furthermore, this study wants to answer what benefits can be obtained from the implementation of this standard on the plantation-based SOE. The main characteristic of IAS is the use of fair value model for biological assets owned by the agriculture-based entity. The use of this model raises a lot of controversy, primarily, associated with relevant quality and reliability of the information it produces. Research used qualitative method with data collection through literature study, survey, interview, and observation. Survey and interview were divided into two major parts, which were: on the compilers of financial statements and the stakeholders. From this study it can be concluded that the PSAK based on IAS 41 have not to be implemented yet in the near future due to IAS 41 will undergo quite significant revision. Currently, the State-Owned Enterprises could use the PSAK plantation SOE that has been issued.

  20. 75 FR 11582 - IOWA Disaster # IA-00023

    Science.gov (United States)

    2010-03-11

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION IOWA Disaster IA-00023 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  1. 78 FR 28939 - Iowa Disaster #IA-00050

    Science.gov (United States)

    2013-05-16

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00050 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  2. 78 FR 36010 - Iowa Disaster #IA-00052

    Science.gov (United States)

    2013-06-14

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00052 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  3. 76 FR 66768 - Iowa Disaster #IA-00033

    Science.gov (United States)

    2011-10-27

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00033 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Iowa...

  4. 75 FR 51507 - Iowa Disaster #IA-00024

    Science.gov (United States)

    2010-08-20

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Iowa...

  5. 75 FR 53006 - Iowa Disaster #IA-00026

    Science.gov (United States)

    2010-08-30

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 2. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only...

  6. 76 FR 55721 - Iowa Disaster #IA-00038

    Science.gov (United States)

    2011-09-08

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00038 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  7. 76 FR 54522 - Iowa Disaster #IA-00037

    Science.gov (United States)

    2011-09-01

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00037 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  8. 76 FR 54521 - Iowa Disaster #IA-00036

    Science.gov (United States)

    2011-09-01

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00036 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major ] disaster for Public Assistance Only for...

  9. 76 FR 29284 - Iowa Disaster #IA-00031

    Science.gov (United States)

    2011-05-20

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00031 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  10. 76 FR 27738 - Iowa Disaster #IA-00030

    Science.gov (United States)

    2011-05-12

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00030 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Iowa dated...

  11. 78 FR 42147 - Iowa Disaster #IA-00054

    Science.gov (United States)

    2013-07-15

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00054 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance only for...

  12. 75 FR 45681 - Iowa Disaster #IA-00025

    Science.gov (United States)

    2010-08-03

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00025 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  13. 75 FR 47035 - Iowa Disaster # IA-00026

    Science.gov (United States)

    2010-08-04

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance only for...

  14. 76 FR 52042 - Iowa Disaster #IA-00035

    Science.gov (United States)

    2011-08-19

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00035 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Iowa Dated....

  15. 75 FR 10329 - Iowa Disaster #IA-00022

    Science.gov (United States)

    2010-03-05

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00022 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  16. Single Degenerate Progenitors of Type Ia Supernovae

    Science.gov (United States)

    Bours, Madelon; Toonen, Silvia; Nelemans, Gijs

    2013-01-01

    There is a general agreement that Type Ia supernovae correspond to the thermonuclear runaway of a white dwarf (WD) in a compact binary. The details of these progenitor systems are still unclear. Using the population synthesis code SeBa and several assumption for the WD retention efficiency, we estimate the delay times and supernova rates for the single degenerate scenario.

  17. 78 FR 48762 - Iowa Disaster #IA-00053

    Science.gov (United States)

    2013-08-09

    ... ADMINISTRATION Iowa Disaster IA-00053 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This...: Submit completed loan applications to: U.S. Small Business Administration, Processing and Disbursement... of Disaster Assistance, U.S. Small Business Administration, 409 3rd Street SW., Suite...

  18. Probing Cosmological Isotropy With Type IA Supernovae

    CERN Document Server

    Bengaly, C A P; Alcaniz, J S

    2015-01-01

    We investigate the validity of the Cosmological Principle by mapping the cosmological parameters $H_0$ and $q_0$ through the celestial sphere. In our analysis, performed in a low-redshift regime to follow a model-independent approach, we use two compilations of type Ia Supernovae (SNe Ia), namely the Union2.1 and the JLA datasets. Firstly, we show that the angular distributions for both SNe Ia datasets are statistically anisotropic at high confidence level ($p$-value $<$ 0.0001), in particular the JLA sample. Then we find that the cosmic expansion and acceleration are mainly of dipolar type, with maximal anisotropic expansion [acceleration] pointing towards $(l,b) \\simeq (326^{\\circ},12^{\\circ})$ [$(l,b) \\simeq (174^{\\circ},27^{\\circ})$], and $(l,b) \\simeq (58^{\\circ},-60^{\\circ})$ [$(l,b) \\simeq (225^{\\circ},51^{\\circ})$] for the Union2.1 and JLA data, respectively. Secondly, we use a geometrical method to test the hypothesis that the non-uniformly distributed SNe Ia events could introduce anisotropic imp...

  19. Merging white dwarfs and SN Ia

    CERN Document Server

    Yungelson, L R

    2016-01-01

    Using population synthesis, we study a double-degenerate (DD) scenario for SNe Ia, aiming to estimate the maximum possible contribution to the rate of SNe from this scenario and the dependence of the delay-time distribution (DTD) on it. We make an extreme assumption that all mergers of super-Chandrasekhar pairs of CO white dwarfs (WDs) and mergers of CO WDs more massive than 0.47 $M_\\odot$ with hybrid or helium WDs more massive than 0.37$M_\\odot$ produce SNe Ia. The models are parametrized by the product of the common envelope efficiency and the parameter of binding energy of stellar envelopes $\\alpha_{ce}\\lambda$, which we vary between 0.25 and 2. The best agreement with observations is obtained for $\\alpha_{ce}\\lambda$=2. A substantial contribution to the rate of SNe Ia is provided by the pairs with a hybrid WD. The estimated Galactic rate of SNe Ia is $6.5 10^{-3}$ per yr (for the mass of the bulge and thin disk equal to $7.2 10^{10} M_\\odot$), which is comparable to the observational estimate $(5.4\\pm0.12...

  20. IAS 17 Leases - A Closer Look

    OpenAIRE

    Muthupandian, K S

    2009-01-01

    The International Accounting Standards Committee issued the the International Accounting Standard 17, Leases. The objective of IAS 17 is to prescribe, for lessees and lessors, the appropriate accounting treatment and disclosures to apply in relation to leases. This article presents a closer look of standard (objective, scope, definitions, accounting treatment, recognition, presentation and disclosures).

  1. IA-2及IA-2β与1型糖尿病

    Institute of Scientific and Technical Information of China (English)

    宗阳; 罗敏

    2000-01-01

    IA-2和IA-2β是近年来发现的两种重要胰岛细胞自身抗原,是引发1型糖尿病胰岛自身免疫反应的重要因素.针对两者的自身抗体存在于半数以上的新诊1型糖尿病患者血清中.IA-2、IA-2β及其抗体检测在1型糖尿病的发病机制研究、诊断、预测和早期防治中具有重要作用.

  2. 75 FR 37292 - Amendment of Class E Airspace; Cherokee, IA

    Science.gov (United States)

    2010-06-29

    ... Cherokee, IA. Decommissioning of the Pilot Rock non-directional beacon (NDB) at Cherokee County Regional Airport, Cherokee, IA has made this action necessary to enhance the safety and management of Instrument... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Cherokee, IA AGENCY:...

  3. 76 FR 73501 - Amendment of Class E Airspace; Carroll, IA

    Science.gov (United States)

    2011-11-29

    ... Carroll, IA. Decommissioning of the Carroll non-directional beacon (NDB) at Arthur N. Neu Airport, Carroll, IA, has made this action necessary to enhance the safety and management of Instrument Flight Rule... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Carroll, IA AGENCY:...

  4. Expression of I-A and I-E,C region-coded Ia antigens on functional B cell subpopulations.

    Science.gov (United States)

    Frelinger, J A; Hibbler, F J; Hill, S W

    1978-12-01

    Ia antigens from specific subregions have been examined on functional B cell populations. Expression of both I-A and I-E,C region antigens was demonstrated on cells required for both lipopolysaccharide mitogenesis and polyclonal activation. Similar I-A and I-E,C subregion expression was found on cells required for response to the T-independent antigen, polyvinylpyrrolidone. TNP-specific IgM and hen egg lysozyme-specific IgG plaque-forming cells also express I-A and I-E,C region antigens. No evidence was found for an Ia- population responsive in the systems tested. Further, no evidence of preferential expression of I-A or I-E,C region antigens was observed in any system examined. Therefore, it appears that B cells express both I-A and I-E,C region-coded Ia antigens.

  5. European freshwater VHSV genotype Ia isolates divide into two distinct subpopulations.

    Science.gov (United States)

    Kahns, S; Skall, H F; Kaas, R S; Korsholm, H; Bang Jensen, B; Jonstrup, S P; Dodge, M J; Einer-Jensen, K; Stone, D; Olesen, N J

    2012-05-15

    Viral haemorrhagic septicaemia (VHS), caused by the novirhabdovirus VHSV, often leads to significant economic losses to European rainbow trout production. The virus isolates are divided into 4 distinct genotypes with additional subgroups including sublineage Ia, isolates of which are the main source of outbreaks in European rainbow trout farming. A significant portion of Danish rainbow trout farms have been considered endemically infected with VHSV since the first disease outbreak was observed in the 1950s. However, following a series of sanitary programs starting in 1965, VHSV has not been detected in Denmark since January 2009. Full-length G-genes of all Danish VHSV isolates that were submitted for diagnostic analyses in the period 2004-2009 were sequenced and analysed. All 58 Danish isolates from rainbow trout grouped with sublineage Ia isolates. Furthermore, VHSV isolates from infected Danish freshwater catchments appear to have evolved into a distinct clade within sublineage Ia, herein designated clade Ia-1, whereas trout isolates originating from other continental European countries cluster in another distinct clade, designated clade Ia-2. In addition, phylogenetic analyses indicate that VHSV Ia-1 strains have caused a few outbreaks in Germany and the UK. It is likely that viruses have been transmitted from infected site(s) out of the Danish environment, although a direct transmission pathway has not been identified. Furthermore, VHSV Ia-2 isolates seem to have been transmitted to Denmark at least once. Interestingly, one viral isolate possibly persisted in a Danish watershed for nearly 4 yr without detection whereas other subclades of VHSV isolates appear to have been eliminated, probably because of implemented eradication procedures.

  6. Reddened, Redshifted, or Intrinsically Red? Understanding Near-ultraviolet Colors of Type Ia Supernovae

    Science.gov (United States)

    Brown, Peter J.; Landez, Nancy J.; Milne, Peter A.; Stritzinger, Maximilian D.

    2017-02-01

    The intrinsic colors of Type Ia supernovae (SNe Ia) are important to understanding their use as cosmological standard candles. Understanding the effects of reddening and redshift on the observed colors are complicated and dependent on the intrinsic spectrum, the filter curves, and the wavelength dependence of reddening. We present ultraviolet and optical data of a growing sample of SNe Ia observed with the Ultraviolet/Optical Telescope on the Swift spacecraft and use this sample to re-examine the near-UV (NUV) colors of SNe Ia. We find that a small amount of reddening (E(B ‑ V) = 0.2 mag) could account for the difference between groups designated as NUV-blue and NUV-red, and a moderate amount of reddening (E(B ‑ V) = 0.5 mag) could account for the whole NUV-optical differences. The reddening scenario, however, is inconsistent with the mid-UV colors and color evolution. The effect of redshift alone only accounts for part of the variation. Using a spectral template of SN2011fe, we can forward model the effects of redshift and reddening and directly compare those with the observed colors. We find that some SNe are consistent with reddened versions of SN2011fe, but most SNe Ia are much redder in the uvw1 ‑ v color than SN2011fe reddened to the same b ‑ v color. The absolute magnitudes show that two out of five NUV-blue SNe Ia are blue because their near-UV luminosity is high, and the other three are optically fainter. We also show that SN 2011fe is not a “normal” SN Ia in the UV, but has colors placing it at the blue extreme of our sample.

  7. Spatial distribution of excitatory synapses on the dendrites of ganglion cells in the mouse retina.

    Science.gov (United States)

    Chen, Yin-Peng; Chiao, Chuan-Chin

    2014-01-01

    Excitatory glutamatergic inputs from bipolar cells affect the physiological properties of ganglion cells in the mammalian retina. The spatial distribution of these excitatory synapses on the dendrites of retinal ganglion cells thus may shape their distinct functions. To visualize the spatial pattern of excitatory glutamatergic input into the ganglion cells in the mouse retina, particle-mediated gene transfer of plasmids expressing postsynaptic density 95-green fluorescent fusion protein (PSD95-GFP) was used to label the excitatory synapses. Despite wide variation in the size and morphology of the retinal ganglion cells, the expression of PSD95 puncta was found to follow two general rules. Firstly, the PSD95 puncta are regularly spaced, at 1-2 µm intervals, along the dendrites, whereby the presence of an excitatory synapse creates an exclusion zone that rules out the presence of other glutamatergic synaptic inputs. Secondly, the spatial distribution of PSD95 puncta on the dendrites of diverse retinal ganglion cells are similar in that the number of excitatory synapses appears to be less on primary dendrites and to increase to a plateau on higher branch order dendrites. These observations suggest that synaptogenesis is spatially regulated along the dendritic segments and that the number of synaptic contacts is relatively constant beyond the primary dendrites. Interestingly, we also found that the linear puncta density is slightly higher in large cells than in small cells. This may suggest that retinal ganglion cells with a large dendritic field tend to show an increased connectivity of excitatory synapses that makes up for their reduced dendrite density. Mapping the spatial distribution pattern of the excitatory synapses on retinal ganglion cells thus provides explicit structural information that is essential for our understanding of how excitatory glutamatergic inputs shape neuronal responses.

  8. Principal component analysis of minimal excitatory postsynaptic potentials.

    Science.gov (United States)

    Astrelin, A V; Sokolov, M V; Behnisch, T; Reymann, K G; Voronin, L L

    1998-02-20

    'Minimal' excitatory postsynaptic potentials (EPSPs) are often recorded from central neurones, specifically for quantal analysis. However the EPSPs may emerge from activation of several fibres or transmission sites so that formal quantal analysis may give false results. Here we extended application of the principal component analysis (PCA) to minimal EPSPs. We tested a PCA algorithm and a new graphical 'alignment' procedure against both simulated data and hippocampal EPSPs. Minimal EPSPs were recorded before and up to 3.5 h following induction of long-term potentiation (LTP) in CA1 neurones. In 29 out of 45 EPSPs, two (N=22) or three (N=7) components were detected which differed in latencies, rise time (Trise) or both. The detected differences ranged from 0.6 to 7.8 ms for the latency and from 1.6-9 ms for Trise. Different components behaved differently following LTP induction. Cases were found when one component was potentiated immediately after tetanus whereas the other with a delay of 15-60 min. The immediately potentiated component could decline in 1-2 h so that the two components contributed differently into early (reflections of synchronized quantal releases. In general, the results demonstrate PCA applicability to separate EPSPs into different components and its usefulness for precise analysis of synaptic transmission.

  9. Amyloid-β depresses excitatory cholinergic synaptic transmission in Drosophila

    Institute of Scientific and Technical Information of China (English)

    Liqun Fang; Jingjing Duan; Dongzhi Ran; Zihao Fan; Ying Yan; Naya Huang; Huaiyu Gu; Yulan Zhu

    2012-01-01

    Objective Decline,disruption,or alterations of nicotinic cholinergic mechanisms contribute to cognitive dysfunctions like Alzheimer's disease (AD).Although amyloid-β (Aβ) aggregation is a pathological hallmark of AD,the mechanisms by which Aβ peptides modulate cholinergic synaptic transmission and memory loss remain obscure.This study was aimed to investigate the potential synaptic modulation by Aβ of the cholinergic synapses between olfactory receptor neurons and projection neurons (PNs) in the olfactory lobe of the fruit fly.Methods Cholinergic spontaneous and miniature excitatory postsynaptic current (mEPSC) were recorded with whole-cell patch clamp from PNs in Drosophila AD models expressing Aβ40,Aβ42,or Aβ42Arc peptides in neural tissue.Results In fly pupae (2 days before eclosion),overexpression of Aβ42 or Aβ42Arc,but not Aβ40,led to a significant decrease of mEPSC frequency,while overexpression of Aβ40,Aβ42,or Aβ42Arc had no significant effect on mEPSC amplitude.In contrast,Pavlovian olfactory associative learning and lifespan assays showed that both short-term memory and lifespan were decreased in the Drosophila models expressing Aβ40,Aβ42,or Aβ42Arc.Conclusion Both electrophysiological and behavioral results showed an effect of Aβ peptide on cholinergic synaptic transmission and suggest a possible mechanism by which Aβ peptides cause cholinergic neuron degeneration and the consequent memory loss.

  10. EIGENVALUE FUNCTIONS IN EXCITATORY-INHIBITORY NEURONAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Zhang Linghai

    2004-01-01

    We study the exponential stability of traveling wave solutions of nonlinear systems of integral differential equations arising from nonlinear, nonlocal, synaptically coupled, excitatory-inhibitory neuronal networks. We have proved that exponential stability of traveling waves is equivalent to linear stability. Moreover, if the real parts of nonzero spectrum of an associated linear differential operator have a uniform negative upper bound, namely, max{Reλ: λ∈σ(L), λ≠ 0} ≤ -D, for some positive constant D, and λ = 0 is an algebraically simple eigenvalue of , then the linear stability follows, where is the linear differential operator obtained by linearizing the nonlinear system about its traveling wave and σ(L) denotes the spectrum of . The main aim of this paper is to construct complex analytic functions (also called eigenvalue or Evans functions) for exploring eigenvalues of linear differential operators to study the exponential stability of traveling waves. The zeros of the eigenvalue functions coincide with the eigenvalues of(L) .When studying multipulse solutions, some components of the traveling waves cross their thresholds for many times. These crossings cause great difficulty in the construction of the eigenvalue functions. In particular, we have to solve an over-determined system to construct the eigenvalue functions. By investigating asymptotic behaviors as z → -co of candidates for eigenfunctions, we find a way to construct the eigenvalue functions.By analyzing the zeros of the eigenvalue functions, we can establish the exponential stability of traveling waves arising from neuronal networks.

  11. 75 FR 16067 - Designation for the Champaign, IL; Emmett, MI; Davenport, IA; Enid, OK; Keokuk, IA; Marshall, MI...

    Science.gov (United States)

    2010-03-31

    ... Register (74 FR 45803), GIPSA requested applications for designation to provide official services in the...; Davenport, IA; Enid, OK; Keokuk, IA; Marshall, MI; and Omaha, NE Areas AGENCY: Grain Inspection, Packers and.... Detroit Emmett, MI (810-395-2105) 4/1/2010 3/31/2013 Eastern Iowa Davenport, IA (563-322-7149). 4/1/2010...

  12. Birthrates and delay times of Type Ia supernovae

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Type Ia supernovae (SNe Ia) play an important role in diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology. However, the nature of the progenitors of SNe Ia is still unclear. In this paper, according to a detailed binary population synthesis study, we obtained SN Ia birthrates and delay times from different progenitor models, and compared them with observations. We find that the Galactic SN Ia birthrate from the double-degenerate (DD) model is close to those inferred from observations, while the birthrate from the single-degenerate (SD) model accounts for only about 1/2-2/3 of the observations. If a single starburst is assumed, the distribution of the delay times of SNe Ia from the SD model is a weak bimodality, where the WD + He channel contributes to the SNe Ia with delay times shorter than 100 Myr, and the WD + MS and WD + RG channels to those with age longer than 1 Gyr.

  13. Coréia aguda na gravidez

    Directory of Open Access Journals (Sweden)

    Walter C. Pereira

    1967-12-01

    Full Text Available São apresentados doze casos de coréia aguda observados entre 150.000 gestantes (1/12.500. A maioria dos surtos ocorreu no segundo trimestre da primeira gravidez. A duração média dos sintomas foi de três meses, não tendo sido registrado caso algum de óbito materno. Todos os partos foram espontâneos e normais. Houve apenas um óbito fetal conseqüente a choque hemorrágico. São tecidas considerações a propósito dos aspectos clínico, laboratorial e prognóstico da coréia gravídica, sendo focalizado mais pormenorizadamente o problema fisiopatogênico dessa afecção.

  14. Excitatory and inhibitory behavioral responses to the pharmacological stimulation of serotonergic function in dorsalis raphe lesioned rats.

    Science.gov (United States)

    Rodríguez Echandía, E L; González, A S; Fóscolo, M R; Broitman, S T

    1988-01-01

    Neurotoxin-induced lesions of 5-HT neurons produce supersensitivity of 5-HT1 receptors without affecting 5-HT2 receptor binding in the brain. This model was used in the present work to analyze the role of 5-HT receptor subtypes in the mechanism controlling the excitatory and inhibitory behavioral responses to the pharmacological stimulation of 5-HT systems. Dorsalis raphe (DR) lesions were made by stereotaxic injection of kainic acid. At day 30 after injection DR-and control rats displayed similar baseline behavior in hole board tests. Three days later DR-and control rats received an ip injection of fluoxetine (5 or 10 mg/kg) 30 min before injecting ip 5-HTP(15 or 30 mg/kg). Immediately before and after each ip injection the excitatory response (myoclonic syndrome) was evaluated. DR-and control-group showed similar scores of myoclonus in response to fluoxetine-5-HTP. The inhibitory response was investigated in hole board trials performed 30 min after the second ip injection. The DR lesion potentiated the behavioral depressive effect of fluoxetine-5-HTP. In agreement with data in the literature the DR lesion caused 74.9% loss of forebrain 5-HT and 75% increases of 3H-5HT binding in cortex membranes. Most components of the excitatory response, which remained unchanged in the DR-lesioned rats, might be related to 5-HT2 receptors. The increased inhibitory response to 5-HT stimulation in DR-lesioned rats would be due to the supersensitivity of 5-HT1 receptors.

  15. Single degenerate supernova type Ia progenitors

    CERN Document Server

    Bours, M C P; Nelemans, G

    2013-01-01

    There is general agreement that supernovae Ia correspond to the thermonuclear runaway of a white dwarf that is part of a compact binary, but the details of the progenitor systems are still unknown and much debated. One of the proposed progenitor theories is the single-degenerate channel in which a white dwarf accretes from a companion, grows in mass, reaches a critical mass limit, and is then consumed after thermonuclear runaway sets in. However, there are major disagreements about the theoretical delay time distribution and the corresponding time-integrated supernova Ia rate from this channel. We investigate whether the differences are due to the uncertainty in the common envelope phase and the fraction of transferred mass that is retained by the white dwarf. This so-called retention efficiency may have a strong influence on the final amount and timing of supernovae Ia. Using the population synthesis code SeBa, we simulated large numbers of binaries for various assumptions on common envelopes and retention e...

  16. New mutation type in pseudohypoparathyroidism type Ia.

    Science.gov (United States)

    Fernandez-Rebollo, Eduardo; Barrio, Raquel; Pérez-Nanclares, Gustavo; Carcavilla, Atilano; Garin, Intza; Castaño, Luis; de Nanclares, Guiomar Pérez

    2008-11-01

    The GNAS gene encodes the alpha-subunit of the stimulatory G proteins, which play a crucial role in intracellular signal transduction of peptide and neurotransmitter receptors. Heterozygous inactivating maternally inherited mutations of GNAS (including translation initiation mutations, amino acid substitutions, nonsense mutations, splice site mutations and small insertions or deletions) lead to a phenotype in which Albright hereditary osteodystrophy is associated with pseudohypoparathyroidism type Ia. We sought to identify the molecular defect in a patient who was thought to have PHP-Ia. The GNAS gene of a 5-year-old boy with brachydactily, mental retardation, pseudohypoparathyroidism and congenital hypothyroidism was investigated. We found a heterozygous inversion of exon 2 and part of intron 1 of de novo origin. Molecular studies of cDNA from blood RNA demonstrated that both the normal and the mutant variants were stable and that new splice-sites were generated. This report demonstrates the first evidence for an inversion at the GNAS gene responsible of pseudohypoparathyroidism type Ia.

  17. Shock Breakout from Type Ia Supernova

    CERN Document Server

    Piro, Anthony L; Weinberg, Nevin N

    2009-01-01

    The mode of explosive burning in Type Ia SNe remains an outstanding problem. It is generally thought to begin as a subsonic deflagration, but this may transition into a supersonic detonation (the DDT). We argue that this transition leads to a breakout shock, which would provide the first unambiguous evidence that DDTs occur. Its main features are a hard X-ray flash (~20 keV) lasting ~0.01 s with a total radiated energy of ~10^{40} ergs, followed by a cooling tail. This creates a distinct feature in the visual light curve, which is separate from the nickel decay. This cooling tail has a maximum absolute visual magnitude of M_V = -9 to -10 at approximately 1 day, which depends most sensitively on the white dwarf radius at the time of the DDT. As the thermal diffusion wave moves in, the composition of these surface layers may be imprinted as spectral features, which would help to discern between SN Ia progenitor models. Since this feature should accompany every SNe Ia, future deep surveys (e.g., m=24) will see i...

  18. Transient oxytocin signaling primes the development and function of excitatory hippocampal neurons.

    Science.gov (United States)

    Ripamonti, Silvia; Ambrozkiewicz, Mateusz C; Guzzi, Francesca; Gravati, Marta; Biella, Gerardo; Bormuth, Ingo; Hammer, Matthieu; Tuffy, Liam P; Sigler, Albrecht; Kawabe, Hiroshi; Nishimori, Katsuhiko; Toselli, Mauro; Brose, Nils; Parenti, Marco; Rhee, JeongSeop

    2017-02-23

    Beyond its role in parturition and lactation, oxytocin influences higher brain processes that control social behavior of mammals, and perturbed oxytocin signaling has been linked to the pathogenesis of several psychiatric disorders. However, it is still largely unknown how oxytocin exactly regulates neuronal function. We show that early, transient oxytocin exposure in vitro inhibits the development of hippocampal glutamatergic neurons, leading to reduced dendrite complexity, synapse density, and excitatory transmission, while sparing GABAergic neurons. Conversely, genetic elimination of oxytocin receptors increases the expression of protein components of excitatory synapses and excitatory synaptic transmission in vitro. In vivo, oxytocin-receptor-deficient hippocampal pyramidal neurons develop more complex dendrites, which leads to increased spine number and reduced γ-oscillations. These results indicate that oxytocin controls the development of hippocampal excitatory neurons and contributes to the maintenance of a physiological excitation/inhibition balance, whose disruption can cause neurobehavioral disturbances.

  19. The Carnegie Supernova Project: Intrinsic Colors of Type Ia Supernovae

    CERN Document Server

    Burns, Christopher R; Phillips, M M; Hsiao, E Y; Contreras, Carlos; Persson, S E; Folatelli, Gaston; Boldt, Luis; Campillay, Abdo; Catellón, Sergio; Freedman, Wendy L; Madore, Barry F; Morrell, Nidia; Salgado, Francisco; Suntzeff, Nicholas B

    2014-01-01

    We present an updated analysis of the intrinsic colors of SNe Ia using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of "normal" SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B-V color-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of Rv, though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, Rv, and the color excess, E(B-V), such t...

  20. Cysteine transport through excitatory amino acid transporter 3 (EAAT3).

    Science.gov (United States)

    Watts, Spencer D; Torres-Salazar, Delany; Divito, Christopher B; Amara, Susan G

    2014-01-01

    Excitatory amino acid transporters (EAATs) limit glutamatergic signaling and maintain extracellular glutamate concentrations below neurotoxic levels. Of the five known EAAT isoforms (EAATs 1-5), only the neuronal isoform, EAAT3 (EAAC1), can efficiently transport the uncharged amino acid L-cysteine. EAAT3-mediated cysteine transport has been proposed to be a primary mechanism used by neurons to obtain cysteine for the synthesis of glutathione, a key molecule in preventing oxidative stress and neuronal toxicity. The molecular mechanisms underlying the selective transport of cysteine by EAAT3 have not been elucidated. Here we propose that the transport of cysteine through EAAT3 requires formation of the thiolate form of cysteine in the binding site. Using Xenopus oocytes and HEK293 cells expressing EAAT2 and EAAT3, we assessed the transport kinetics of different substrates and measured transporter-associated currents electrophysiologically. Our results show that L-selenocysteine, a cysteine analog that forms a negatively-charged selenolate ion at physiological pH, is efficiently transported by EAATs 1-3 and has a much higher apparent affinity for transport when compared to cysteine. Using a membrane tethered GFP variant to monitor intracellular pH changes associated with transport activity, we observed that transport of either L-glutamate or L-selenocysteine by EAAT3 decreased intracellular pH, whereas transport of cysteine resulted in cytoplasmic alkalinization. No change in pH was observed when cysteine was applied to cells expressing EAAT2, which displays negligible transport of cysteine. Under conditions that favor release of intracellular substrates through EAAT3 we observed release of labeled intracellular glutamate but did not detect cysteine release. Our results support a model whereby cysteine transport through EAAT3 is facilitated through cysteine de-protonation and that once inside, the thiolate is rapidly re-protonated. Moreover, these findings suggest

  1. Activation of perineuronal net-expressing excitatory neurons during associative memory encoding and retrieval

    Science.gov (United States)

    Morikawa, Shota; Ikegaya, Yuji; Narita, Minoru; Tamura, Hideki

    2017-01-01

    Perineuronal nets (PNNs), proteoglycan-rich extracellular matrix structures, are thought to be expressed around inhibitory neurons and contribute to critical periods of brain function and synaptic plasticity. However, in some specific brain regions such as the amygdala, PNNs were predominantly expressed around excitatory neurons. These neurons were recruited during auditory fear conditioning and memory retrieval. Indeed, the activation of PNN-expressing excitatory neurons predicted cognitive performance. PMID:28378772

  2. Excitatory effects of thyrotropin-releasing hormone (TRH) in hypoglossal motoneurons

    DEFF Research Database (Denmark)

    Rekling, J C

    1990-01-01

    The effect of thyrotropin-releasing hormone (TRH) was studied in 30 hypoglossal motoneurons from brainstem slices of guinea pigs. Bath application of TRH resulted in an increase of the spontaneous excitatory synaptic activity, depolarization of the neurons, increase of the input resistance...... and change of the duration of the falling phase of excitatory postsynaptic potentials. The depolarizing response and membrane conductance change was the result of a direct postsynaptic action of TRH, possibly mediated by a reduction of a potassium conductance....

  3. Optical Identification of Cepheids in 19 Host Galaxies of Type Ia Supernovae and NGC 4258 with the Hubble Space Telescope

    CERN Document Server

    Hoffmann, Samantha L; Riess, Adam G; Yuan, Wenlong; Casertano, Stefano; Filippenko, Alexei V; Tucker, Brad E; Chornock, Ryan; Silverman, Jeffrey M; Welch, Douglas L; Goobar, Ariel; Amanullah, Rahman

    2016-01-01

    We present results of an optical search for Cepheid variable stars using the Hubble Space Telescope (HST) in 19 hosts of Type Ia supernovae (SNe Ia) and the maser-host galaxy NGC 4258, conducted as part of the SH0ES project (Supernovae and H0 for the Equation of State of dark energy). The targets include 9 newly imaged SN Ia hosts using a novel strategy based on a long-pass filter that minimizes the number of HST orbits required to detect and accurately determine Cepheid properties. We carried out a homogeneous reduction and analysis of all observations, including new universal variability searches in all SN Ia hosts, that yielded a total of 2200 variables with well-defined selection criteria -- the largest such sample identified outside the Local Group. These objects are used in a companion paper to determine the local value of H0 with a total uncertainty of 2.4%.

  4. LRRTM3 Regulates Excitatory Synapse Development through Alternative Splicing and Neurexin Binding

    Directory of Open Access Journals (Sweden)

    Ji Won Um

    2016-02-01

    Full Text Available The four members of the LRRTM family (LRRTM1-4 are postsynaptic adhesion molecules essential for excitatory synapse development. They have also been implicated in neuropsychiatric diseases. Here, we focus on LRRTM3, showing that two distinct LRRTM3 variants generated by alternative splicing regulate LRRTM3 interaction with PSD-95, but not its excitatory synapse-promoting activity. Overexpression of either LRRTM3 variant increased excitatory synapse density in dentate gyrus (DG granule neurons, whereas LRRTM3 knockdown decreased it. LRRTM3 also controlled activity-regulated AMPA receptor surface expression in an alternative splicing-dependent manner. Furthermore, Lrrtm3-knockout mice displayed specific alterations in excitatory synapse density, excitatory synaptic transmission and excitability in DG granule neurons but not in CA1 pyramidal neurons. Lastly, LRRTM3 required only specific splice variants of presynaptic neurexins for their synaptogenic activity. Collectively, our data highlight alternative splicing and differential presynaptic ligand utilization in the regulation of LRRTMs, revealing key regulatory mechanisms for excitatory synapse development.

  5. Multiple mechanisms of fast excitatory synaptic transmission in the enteric nervous system.

    Science.gov (United States)

    Galligan, J J; LePard, K J; Schneider, D A; Zhou, X

    2000-07-01

    The enteric nervous system (ENS) can control gastrointestinal function independent of direct connections with the central nervous system. Enteric nerves perform this important function using multiple mechanisms of excitatory neurotransmission in enteric ganglia. Fast excitatory synaptic transmission in the autonomic nervous system (ANS) is largely mediated by acetylcholine (ACh) acting at nicotinic cholinergic receptors but in the ENS there are noncholinergic fast excitatory neurotransmitters. There are two broad types of neurons in the ENS: S neurons and AH neurons. S neurons are interneurons and motoneurons while AH neurons are sensory neurons. Three subsets of S neurons in the myenteric plexus can be distinguished on the basis of the neurotransmitters producing fast excitatory postsynaptic potentials (fEPSPs) in each subset. In one subset, fEPSPs are mediated solely by ACh acting at nicotinic cholinergic receptors. In a second subset of S neurons, ATP acting at P2X purine receptors and ACh contribute to the fEPSP while in a third subset, fEPSPs are mediated by 5-hydroxytryptamine (5-HT) acting at 5-HT(3) receptors and ACh. Some AH neurons also receive fast excitatory synaptic input. The fEPSPs recorded from AH neurons are mediated ACh and also by glutamate acting at alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors. Multiple mechanisms of fast excitatory synaptic transmission in the ENS are likely to contribute to its capacity to regulate complex gastrointestinal functions.

  6. Inhibitory and excitatory amino acids in the cerebrospinal fluid of children with two types of cerebral palsy

    Institute of Scientific and Technical Information of China (English)

    Haibin Yuan; Li Wang; Fei Yin; Li Li; Jing Peng

    2008-01-01

    BACKGROUND: Under normal conditions, excitatory amino acids are dynamically balanced with inhibitory amino acids. Excitatory amino acids have been implicated in perinatal brain injury. OBJECTIVE: To investigate differences in the levels of the excitatory amino acids glutamic acid and aspartic acid, and the inhibitory amino acid gamma-aminobutyric acid (GABA) in the cerebrospinal fluid (CSF) of children with spastic cerebral palsy or athetotic cerebral palsy. DESIGN, TIME AND SETTING: Case-control exploratory observation of neurotransmitter in patients. The experiment was performed in the Pediatrics Department of the Second Affiliated Hospital of Changsba Medical College, the Cerebral Palsy Center of Xiangtan Affiliated Hospital of South China University and the Pediatrics Department of Xiangya Hospital, between February 2006 and May 2007. PARTICIPANTS: We selected 27 children with cerebral palsy, including 13 with spastic cerebral palsy and 14 with athetotic cerebral palsy. We selected 10 patients who were not affected by any neurological disease as controls. METHODS: Two mL blood-free CSF was harvested between the third and fourth lumbar vertebrae of each patient after anesthesia, and stored at 70℃. One mL CSF was mixed with 10 mg sulfosalicylic acid and placed in ice-bath for 10 minutes, then centrifuged 2 000 g for 10 minutes. The supernatant was collected for amino acid quantitation. MAIN OUTCOME MEASURES: The concentrations of glutamic acid, aspartic acid and GABA in the CSF were determined by high-performance liquid chromatography and fluorometric method. The correlation of glutamie acid, aspartic acid and GABA levels with muscular tension in children with cerebral palsy was analyzed using linear dependence. RESULTS: The concentration of GABA was significantly lower in both spastic cerebral palsy and athetotic cerebral palsy patients than in the control group (P 0.05). CONCLUSION: Spastic cerebral palsy and athetotic cerebral palsy patients exhibit an

  7. Tests of Environmental Effects on SN Ia Production

    Science.gov (United States)

    Strolger, Louis-Gregory; van Dyk, Schuyler; Wolff, Schuyler; Campbell, Lachlan; Sadler, Suzanna; Pease, April

    2011-02-01

    The largely unknown type Ia supernova mechanism remains one of the largest sources of possible systematic uncertainty in achieving precise measures of dark energy. The host galaxy environments of SNe Ia provide our best opportunity for constraining the mechanism(s) of the SN Ia progenitor system, i.e., the stars involved, the incubation times, and the sensitivity of SNe Ia to changes in the local gas-phase metallicity. The latter can affect the luminosity of the resultant Ia event, and possibly the success in ultimately yielding a SN Ia event. We seek to solidify possible environmental trends in SN Ia rates from direct measures of host galaxy properties, using the sample collected by the Nearby Galaxies Supernova Search project. This study will uncover which has the greatest influence on SN Ia production efficiency: parent population age, rate of star-formation, or metallicity. Here, we propose to continue our analysis using the Mayall 4m + RCSP to obtain broad SEDs, R_23 metallicities, and star formation rates for 18 of the 25 remaining host galaxies (all z≤0.15) from the NGSS sample (20 targets were obtained in the 2010 semesters). These data will be combined with the remaining sample to be completed in the 2011B semester. The sample will provide a validity test of the mostly indirect trends being established for SNe Ia from the LOSS, SDSS, SNfactory and other surveys, and ultimately steer future investigations towards more precise SN Ia cosmology.

  8. CfA Nearby Supernova Ia Light Curves

    Science.gov (United States)

    Hicken, Malcolm; Berlind, P.; Blondin, S.; Calkins, M.; Challis, P.; Esquerdo, G.; Everett, M.; Fernandez, J.; Jha, S.; Kirshner, R. P.; Latham, D.; Modjaz, M.; Rest, A.; Wood-Vasey, M.

    2007-12-01

    Type Ia supernovae (SN Ia) are central in measuring the accelerated expansion of the Universe and the properties of the underlying dark energy. Nearby SN Ia are compared with distant ones to establish the history of cosmic expansion. In fact, current efforts in SN Ia cosmology are constrained by the limited number of well-observed nearby SN Ia. A significantly improved sample of nearby SN Ia, fully covering the space of Ia properties, is needed to maximize the utility of high-redshift SN Ia. Our ongoing project at the CfA has collected such a set of 170 SN Ia. We have used the FLWO 1.2m telescope. About half of our objects were observed in UBVRI with the 4Shooter camera and have an average of 10 epochs each while the other half was taken in UBVr'i' with the Keplercam instrument and have an average of 17 epochs each. We have now reduced this sample of over 25000 images and present calibrated light curves of these SN Ia along with an analysis of their properties. The CfA Supernova program is supported in part by the National Science Foundation through grant AST-0606772 to Harvard University.

  9. Statistical computer model analysis of the reciprocal and recurrent inhibitions of the Ia-EPSP in α-motoneurons.

    Science.gov (United States)

    Gradwohl, G; Grossman, Y

    2013-01-01

    We simulate the inhibition of Ia-glutamatergic excitatory postsynaptic potential (EPSP) by preceding it with glycinergic recurrent (REN) and reciprocal (REC) inhibitory postsynaptic potentials (IPSPs). The inhibition is evaluated in the presence of voltage-dependent conductances of sodium, delayed rectifier potassium, and slow potassium in five α-motoneurons (MNs). We distribute the channels along the neuronal dendrites using, alternatively, a density function of exponential rise (ER), exponential decay (ED), or a step function (ST). We examine the change in EPSP amplitude, the rate of rise (RR), and the time integral (TI) due to inhibition. The results yield six major conclusions. First, the EPSP peak and the kinetics depending on the time interval are either amplified or depressed by the REC and REN shunting inhibitions. Second, the mean EPSP peak, its TI, and RR inhibition of ST, ER, and ED distributions turn out to be similar for analogous ranges of G. Third, for identical G, the large variations in the parameters' values can be attributed to the sodium conductance step (g(Na_step)) and the active dendritic area. We find that small g(Na_step) on a few dendrites maintains the EPSP peak, its TI, and RR inhibition similar to the passive state, but high g(Na_step) on many dendrites decrease the inhibition and sometimes generates even an excitatory effect. Fourth, the MN's input resistance does not alter the efficacy of EPSP inhibition. Fifth, the REC and REN inhibitions slightly change the EPSP peak and its RR. However, EPSP TI is depressed by the REN inhibition more than the REC inhibition. Finally, only an inhibitory effect shows up during the EPSP TI inhibition, while there are both inhibitory and excitatory impacts on the EPSP peak and its RR.

  10. Computer simulations of neural mechanisms explaining upper and lower limb excitatory neural coupling

    Directory of Open Access Journals (Sweden)

    Ferris Daniel P

    2010-12-01

    Full Text Available Abstract Background When humans perform rhythmic upper and lower limb locomotor-like movements, there is an excitatory effect of upper limb exertion on lower limb muscle recruitment. To investigate potential neural mechanisms for this behavioral observation, we developed computer simulations modeling interlimb neural pathways among central pattern generators. We hypothesized that enhancement of muscle recruitment from interlimb spinal mechanisms was not sufficient to explain muscle enhancement levels observed in experimental data. Methods We used Matsuoka oscillators for the central pattern generators (CPG and determined parameters that enhanced amplitudes of rhythmic steady state bursts. Potential mechanisms for output enhancement were excitatory and inhibitory sensory feedback gains, excitatory and inhibitory interlimb coupling gains, and coupling geometry. We first simulated the simplest case, a single CPG, and then expanded the model to have two CPGs and lastly four CPGs. In the two and four CPG models, the lower limb CPGs did not receive supraspinal input such that the only mechanisms available for enhancing output were interlimb coupling gains and sensory feedback gains. Results In a two-CPG model with inhibitory sensory feedback gains, only excitatory gains of ipsilateral flexor-extensor/extensor-flexor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 26%. In a two-CPG model with excitatory sensory feedback gains, excitatory gains of contralateral flexor-flexor/extensor-extensor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 100%. However, within a given excitatory sensory feedback gain, enhancement due to excitatory interlimb gains could only reach levels up to 20%. Interconnecting four CPGs to have ipsilateral flexor-extensor/extensor-flexor coupling, contralateral flexor-flexor/extensor-extensor coupling, and bilateral flexor-extensor/extensor-flexor coupling could enhance

  11. Cysteine transport through excitatory amino acid transporter 3 (EAAT3.

    Directory of Open Access Journals (Sweden)

    Spencer D Watts

    Full Text Available Excitatory amino acid transporters (EAATs limit glutamatergic signaling and maintain extracellular glutamate concentrations below neurotoxic levels. Of the five known EAAT isoforms (EAATs 1-5, only the neuronal isoform, EAAT3 (EAAC1, can efficiently transport the uncharged amino acid L-cysteine. EAAT3-mediated cysteine transport has been proposed to be a primary mechanism used by neurons to obtain cysteine for the synthesis of glutathione, a key molecule in preventing oxidative stress and neuronal toxicity. The molecular mechanisms underlying the selective transport of cysteine by EAAT3 have not been elucidated. Here we propose that the transport of cysteine through EAAT3 requires formation of the thiolate form of cysteine in the binding site. Using Xenopus oocytes and HEK293 cells expressing EAAT2 and EAAT3, we assessed the transport kinetics of different substrates and measured transporter-associated currents electrophysiologically. Our results show that L-selenocysteine, a cysteine analog that forms a negatively-charged selenolate ion at physiological pH, is efficiently transported by EAATs 1-3 and has a much higher apparent affinity for transport when compared to cysteine. Using a membrane tethered GFP variant to monitor intracellular pH changes associated with transport activity, we observed that transport of either L-glutamate or L-selenocysteine by EAAT3 decreased intracellular pH, whereas transport of cysteine resulted in cytoplasmic alkalinization. No change in pH was observed when cysteine was applied to cells expressing EAAT2, which displays negligible transport of cysteine. Under conditions that favor release of intracellular substrates through EAAT3 we observed release of labeled intracellular glutamate but did not detect cysteine release. Our results support a model whereby cysteine transport through EAAT3 is facilitated through cysteine de-protonation and that once inside, the thiolate is rapidly re-protonated. Moreover, these

  12. Spectroscopy of twelve Type Ia supernovae at intermediate redshift

    CERN Document Server

    Balland, C; Pain, R; Walton, N A; Amanullah, R; Astier, Pierre; Ellis, Richard S; Fabbro, S; Goobar, A; Hardin, D; Hook, I M; Irwin, M J; McMahon, R M; Mendez, J M; Ruiz-Lapuente, P; Sainton, G; Schahmaneche, K; Stanishev, V

    2005-01-01

    We present spectra of twelve Type Ia supernovae obtained in 1999 at the William Herschel Telescope and the Nordic Optical Telescope during a search for Type Ia supernovae (SN Ia) at intermediate redshift. The spectra range from z=0.178 to z=0.493, including five high signal-to-noise ratio SN Ia spectra in the still largely unexplored range 0.15 < z < 0.3. Most of the spectra were obtained before or around restframe B-band maximum light. None of them shows the peculiar spectral features found in low-redshift over- or under-luminous SN Ia. Expansion velocities of characteristic spectral absorption features such as SiII at 6355 angs., SII at 5640 angs. and CaII at 3945 angs. are found consistent with their low-z SN Ia counterparts.

  13. A family of excitatory peptide toxins from venomous crassispirine snails: using Constellation Pharmacology to assess bioactivity.

    Science.gov (United States)

    Imperial, Julita S; Cabang, April B; Song, Jie; Raghuraman, Shrinivasan; Gajewiak, Joanna; Watkins, Maren; Showers-Corneli, Patrice; Fedosov, Alexander; Concepcion, Gisela P; Terlau, Heinrich; Teichert, Russell W; Olivera, Baldomero M

    2014-10-01

    The toxinology of the crassispirine snails, a major group of venomous marine gastropods within the superfamily Conoidea, is largely unknown. Here we define the first venom peptide superfamily, the P-like crassipeptides, and show that the organization of their gene sequences is similar to conotoxin precursors. We provide evidence that one peptide family within the P-like crassipeptide superfamily includes potassium-channel (K-channel) blockers, the κP-crassipeptides. Three of these peptides were chemically synthesized (cce9a, cce9b and iqi9a). Using conventional electrophysiology, cce9b was shown to be an antagonist of both a human Kv1.1 channel isoform (Shaker subfamily of voltage-gated K channels) and a Drosophila K-channel isoform. We assessed the bioactivity of these peptides in native mammalian dorsal root ganglion neurons in culture. We demonstrate that two of these crassipeptides, cce9a and cce9b, elicited an excitatory phenotype in a subset of small-diameter capsaicin-sensitive mouse DRG neurons that were also affected by κJ-conotoxin PlXIVA (pl14a), a blocker of Kv1.6 channels. Given the vast complexity of heteromeric K-channel isoforms, this study demonstrates that the crassispirine venoms are a potentially rich source for discovering novel peptides that can help to identify and characterize the diversity of K-channel subtypes expressed in native neurons and other cell types.

  14. Anatomy and function of an excitatory network in the visual cortex.

    Science.gov (United States)

    Lee, Wei-Chung Allen; Bonin, Vincent; Reed, Michael; Graham, Brett J; Hood, Greg; Glattfelder, Katie; Reid, R Clay

    2016-04-21

    Circuits in the cerebral cortex consist of thousands of neurons connected by millions of synapses. A precise understanding of these local networks requires relating circuit activity with the underlying network structure. For pyramidal cells in superficial mouse visual cortex (V1), a consensus is emerging that neurons with similar visual response properties excite each other, but the anatomical basis of this recurrent synaptic network is unknown. Here we combined physiological imaging and large-scale electron microscopy to study an excitatory network in V1. We found that layer 2/3 neurons organized into subnetworks defined by anatomical connectivity, with more connections within than between groups. More specifically, we found that pyramidal neurons with similar orientation selectivity preferentially formed synapses with each other, despite the fact that axons and dendrites of all orientation selectivities pass near (<5 μm) each other with roughly equal probability. Therefore, we predict that mechanisms of functionally specific connectivity take place at the length scale of spines. Neurons with similar orientation tuning formed larger synapses, potentially enhancing the net effect of synaptic specificity. With the ability to study thousands of connections in a single circuit, functional connectomics is proving a powerful method to uncover the organizational logic of cortical networks.

  15. Comparing the efficacy of excitatory transcranial stimulation methods measuring motor evoked potentials.

    Science.gov (United States)

    Moliadze, Vera; Fritzsche, Georg; Antal, Andrea

    2014-01-01

    The common aim of transcranial stimulation methods is the induction or alterations of cortical excitability in a controlled way. Significant effects of each individual stimulation method have been published; however, conclusive direct comparisons of many of these methods are rare. The aim of the present study was to compare the efficacy of three widely applied stimulation methods inducing excitability enhancement in the motor cortex: 1 mA anodal transcranial direct current stimulation (atDCS), intermittent theta burst stimulation (iTBS), and 1 mA transcranial random noise stimulation (tRNS) within one subject group. The effect of each stimulation condition was quantified by evaluating motor-evoked-potential amplitudes (MEPs) in a fixed time sequence after stimulation. The analyses confirmed a significant enhancement of the M1 excitability caused by all three types of active stimulations compared to sham stimulation. There was no significant difference between the types of active stimulations, although the time course of the excitatory effects slightly differed. Among the stimulation methods, tRNS resulted in the strongest and atDCS significantly longest MEP increase compared to sham. Different time courses of the applied stimulation methods suggest different underlying mechanisms of action. Better understanding may be useful for better targeting of different transcranial stimulation techniques.

  16. Constraining Cosmic Evolution of Type Ia Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

    2008-02-13

    We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

  17. Distinct modifications of convergent excitatory and inhibitory inputs in developing olfactory circuits.

    Science.gov (United States)

    Ma, T-F; Chen, P-H; Hu, X-Q; Zhao, X-L; Tian, T; Lu, W

    2014-06-06

    The interaction between excitatory and inhibitory inputs is critical to neuronal signal processing. However, little is known about this fundamental property, largely due to the inability to clearly isolate the respective inputs. Here we took advantage of the characteristic stereotypical architecture of synaptic connections in the main olfactory bulb, which enabled us to entirely separate excitatory and inhibitory inputs. Using paired stimulation of two glomeruli located apart at different intensities, we separately elicited excitatory and inhibitory inputs and mimicked stimulation of competing mitral cells (MCs) with different odorants. We performed dual whole-cell patch recording of evoked excitatory postsynaptic responses (EPSPs) and inhibitory postsynaptic responses (IPSPs) in current-clamp mode from two competitive MCs that are connected to the two stimulated glomeruli in slices of the main olfactory bulb in 2-3-week-old rats. We deliberately held the recorded cells at a relative hyperpolarized potential. This manipulation not only suppressed action potential generation but also excluded the possible contamination of inhibitory components in excitatory inputs. We found that in weakly activated MCs repetitive EPSP-IPSP interactions (5 Hz, 180 times) induced long-term potentiation (LTP) and long-term depression (LTD) in convergent excitatory and inhibitory inputs, respectively. Unexpectedly, these forms of plasticity depend on activity of somatic (mainly non-synaptic) NMDA receptors (NMDARs). In contrast, the same repetitive stimulation induced the LTP of excitatory inputs in strongly activated MCs (MC2) that require activity of synaptic NMDARs. These distinct forms of plasticity in the developing olfactory circuit may represent a novel rule of modification in convergent inputs that leads to decorrelation of inputs and facilitates odor discrimination.

  18. Type Ia Supernovae and the discovery of the Cosmic Acceleration

    CERN Document Server

    Clocchiatti, Alejandro

    2011-01-01

    I present a review of the research and analysis paths that converged to make Type Ia SNe the most mature cosmological distance estimator of the present time. The narrative starts with the first works in the early decades of the 20th century and finishes with the more recent results. The review was written by a member of the High Z Supernova Search Team, the international group of astronomers that discovered Cosmic Acceleration in 1998. This result, confirmed by the Supernova Cosmology Project in 1999, received an impressive string of recognition culminating with the current Nobel prize in Physics. The review is presented thinking of physicists with a strong interest in Cosmology, who might have pondered why was that, after decades of not being able to agree upon the rate of cosmic expansion, astronomers were so quick to concur on cosmic acceleration.

  19. The Implementation of IAS 16 and IAS 41 at Andrew Peller Limited

    Science.gov (United States)

    Lapointe-Antunes, Pascale; Moore, James

    2013-01-01

    This case asks students to play the role of Doug Grodeckie, Manager of Financial Reporting at Andrew Peller Limited (APL). Doug was asked to prepare a report analyzing Andrew Peller Limited's current tangible long-lived assets disclosures and making recommendations on how best to comply with International Accounting Standard (IAS) 16 Property,…

  20. Search for Type Ia supernova NUV-optical subclasses

    Science.gov (United States)

    Cinabro, David; Scolnic, Daniel; Kessler, Richard; Li, Ashley; Miller, Jake

    2017-04-01

    In response to a recently reported observation of evidence for two classes of Type Ia supernovae (SNe Ia) distinguished by their brightness in the rest-frame near-ultraviolet (NUV), we search for the phenomenon in publicly available light-curve data. We use the SNANA supernova analysis package to simulate SN Ia light curves in the Sloan Digital Sky Survey (SDSS) Supernova Search and the Supernova Legacy Survey (SNLS) with a model of two distinct ultraviolet classes of SNe Ia and a conventional model with a single broad distribution of SN-Ia ultraviolet brightnesses. We compare simulated distributions of rest-frame colours with these two models to those observed in 158 SNe Ia in the SDSS and SNLS data. The SNLS sample of 99 SNe Ia is in clearly better agreement with a model with one class of SN Ia light curves and shows no evidence for distinct NUV sub-classes. The SDSS sample of 59 SNe Ia with poorer colour resolution does not distinguish between the two models.

  1. Search For Type Ia Supernova NUV-Optical Subclasses

    CERN Document Server

    Cinabro, David; Kessler, Richard; Li, Ashley; Miller, Jake

    2016-01-01

    In response to a recently reported observation of evidence for two classes of Type Ia Supernovae (SNe Ia) distinguished by their brightness in the rest-frame near ultraviolet (NUV), we search for the phenomenon in publicly available light-curve data. We use the SNANA supernova analysis package to simulate SN Ia-light curves in the Sloan Digital Sky Survey Supernova Search (SDSS) and the Supernova Legacy Survey (SNLS) with a model of two distinct ultraviolet classes of SNe Ia and a conventional model with a single broad distribution of SN-Ia ultraviolet brightnesses. We compare simulated distributions of rest-frame colors with these two models to those observed in 158 SNe Ia in the SDSS and SNLS data. The SNLS sample of 99 SNe Ia is in clearly better agreement with a model with one class of SN Ia light curves and shows no evidence for distinct NUV sub-classes. The SDSS sample of 59 SNe Ia with poorer color resolution does not distinguish between the two models.

  2. SNe Ia: Can Chandrasekhar Mass Explosions Reproduce the Observed Zoo?

    CERN Document Server

    Baron, E

    2014-01-01

    The question of the nature of the progenitor of Type Ia supernovae (SNe Ia) is important both for our detailed understanding of stellar evolution and for their use as cosmological probes of the dark energy. Much of the basic features of SNe Ia can be understood directly from the nuclear physics, a fact which Gerry would have appreciated. We present an overview of the current observational and theoretical situation and show that it not incompatible with most SNe Ia being the results of thermonuclear explosions near the Chandrasekhar mass.

  3. Tests of Environmental Effects on Type Ia Supernova Production

    Science.gov (United States)

    Sadler, Suzanna M.; Strolger, L.; Wolff, S.

    2011-01-01

    The host galaxy environments of type Ia supernovae (SNe Ia) provide our best opportunity for constraining the mechanism(s) of the SN Ia progenitor system, i.e., the stars involved, the incubation times, and the sensitivity of SNe Ia to changes in the local gas-phase metallicity. The latter can affect the luminosity of the resultant event, and possibly the success in ultimately yielding a SN Ia. We seek to solidify possible environmental trends in SN Ia rates from direct measures of host galaxy properties, using the sample collected by the Nearby Galaxies Supernova Search project. This study will uncover which has the greatest influence on SN Ia production efficiency: parent population age, rate of star-formation, or metallicity. Here, we will show some preliminary results from SSP model fitting (of age and [Fe/H]) to a selection of hosts obtained thus far from this study. The complete sample will provide a validity test of the mostly indirect trends being established for SNe Ia from the LOSS, SDSS, SNfactory and other surveys, and may ultimately steer future investigations towards more precise SN Ia cosmology.

  4. Near-Infrared Properties of Type Ia Supernovae

    Science.gov (United States)

    Phillips, M. M.

    2012-02-01

    The photometric properties of Type Ia supernovae (SNe Ia) in the near-infrared as garnered from observations made over the last 30 years are reviewed. During this period, light curves for more than 120 nearby SNe Ia have been published, revealing considerable homogeneity but also some fascinating differences. These data have confirmed that, for all but the fastest declining objects, SNe Ia are essentially perfect standard candles in the near-infrared, displaying only a slight dependence of peak luminosity on decline rate and color.

  5. Ages of Type Ia Supernovae Over Cosmic Time

    CERN Document Server

    Childress, Michael J; Zahid, H Jabran

    2014-01-01

    We derive empirical models for galaxy mass assembly histories, and convolve these with theoretical delay time distribution (DTD) models for Type Ia supernovae (SNe Ia) to derive the distribution of progenitor ages for all SNe Ia occurring at a given epoch of cosmic time. In actively star-forming galaxies, the progression of the star formation rate is shallower than a $t^{-1}$ SN Ia DTD, so mean SN Ia ages peak at the DTD peak in all star-forming galaxies at all epochs of cosmic history. In passive galaxies which have ceased star formation through some quenching process, the SN Ia age distribution peaks at the quenching epoch, which in passive galaxies evolves in redshift to track the past epoch of major star formation. Our models reproduce the SN Ia rate evolution in redshift, the relationship between SN Ia stretch and host mass, and the distribution of SN Ia host masses in a manner qualitatively consistent with observations. Our model naturally predicts that low-mass galaxies tend to be actively star-forming...

  6. Analytical Expressions For Light-curves of Supernovae Type Ia

    CERN Document Server

    Dado, Shlomo

    2013-01-01

    A simple analytical model is used to derive the main properties of supernovae type Ia (SNe Ia), which are produced by the thermonuclear explosion of accreting C-O white dwarfs that cross the Chandrasekhar mass limit. The few underlying physical assumptions of the model yield analytical expressions that reproduce quite well the observed bolometric light-curves of SNe Ia and the empirical brighter-slower and brighter-bluer relationships that were used to standardize SNe Ia for their use as distance indicators, which led to the discovery of the accelerating expansion of the universe.

  7. An Approach to Information Architecture(IA)%信息构建(Information Architecture,IA)探析

    Institute of Scientific and Technical Information of China (English)

    荣毅虹; 梁战平

    2003-01-01

    本文以Internet发展为背景,分前网络时期和网络时期两个阶段对IA进行了考察,提出了狭义IA(书本IA、网站IA)和广义IA,并对其含义、内容和作用进行了探讨和论述.

  8. The Distant Type Ia Supernova Rate

    Science.gov (United States)

    Pain, R.; Fabbro, S.; Sullivan, M.; Ellis, R. S.; Aldering, G.; Astier, P.; Deustua, S. E.; Fruchter, A. S.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hardin, D.; Hook, I. M.; Howell, D. A.; Irwin, M. J.; Kim, A. G.; Kim, M. Y.; Knop, R. A.; Lee, J. C.; Perlmutter, S.; Ruiz-Lapuente, P.; Schahmaneche, K.; Schaefer, B.; Walton, N. A.

    2002-05-28

    We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample, which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean red shift z {approx_equal} 0.55 of 1.53 {sub -0.25}{sub -0.31}{sup 0.28}{sup 0.32} x 10{sup -4} h{sup 3} Mpc{sup -3} yr{sup -1} or 0.58{sub -0.09}{sub -0.09}{sup +0.10}{sup +0.10} h{sup 2} SNu(1 SNu = 1 supernova per century per 10{sup 10} L{sub B}sun), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models.

  9. Neutronization and Energetics of Type Ia Supernovae

    Science.gov (United States)

    Seitenzahl, I. R.; Peng, F.; Townsley, D. M.; Calder, A. C.

    2005-12-01

    Type Ia supernovae are critical distance indicators for cosmology. The lightcurves are powered by the decay of radioactive nickel and cobalt isotopes. The amount of nickel produced in the supernova event depends on the detailed trajectories of the hydrodynamic evolution of the explosion. A key ingredient in numerical simulations of the deflagration phase of Type Ia supernovae is the nuclear flame model. A realistic model must accurately describe the nuclear energy released, the timescale on which the energy release occurs, and the changes in composition that constitute the burning. Once the flame has passed, the hot products of the burning constitute a nuclear statistical equilibrium (NSE) abundance distribution. Since the NSE abundances, and hence derived quantities such as the mean binding energy per nucleon, are functions of the density, temperature and electron fraction, it is important to continuously adjust the NSE state of the ashes during the hydrodynamic evolution of the star. Weak interactions influence the energetics and evolution via the change in degeneracy pressure due to captured electrons, the energy losses carried away by neutrinos, and the readjustment of the NSE state following a change in the electron fraction. We have developed a NSE-based model, which implements these features for a hydrodynamical evolution code.

  10. Dark matter ignition of type Ia supernovae

    CERN Document Server

    Bramante, Joseph

    2015-01-01

    Recent studies of low redshift type Ia supernovae (SNIa) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SNIa progenitors. We show that $0.1-10$ PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SNIa. We combine data on SNIa masses with data on the ages of SNIa-adjacent stars. This combination reveals a $ 3 \\sigma$ inverse correlation between SNIa masses and ignition ages, which could result from increased capture of dark matter in 1.4 versus 1.1 solar mass white dwarfs. Future studies of SNIa in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SNI...

  11. The distant Type Ia supernova rate

    CERN Document Server

    Pain, R; Sullivan, M; Ellis, Richard S; Aldering, G; Astier, Pierre; Duestua, S E; Fruchter, A S; Goldhaber, Gerson; Goobar, A; Groom, D E; Hardin, D; Hook, I M; Howell, D A; Irwin, M J; Kim, A G; Kim, M Y; Knop, R A; Lee, J C; Lidman, C E; McMahon, R G; Nugent, P; Panagia, N; Pennypacker, C R; Perlmutter, S; Ruiz-Lapuente, P; Schahmaneche, K; Schaefer, B; Walton, N A

    2001-01-01

    We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample, which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially-flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean redshift $z\\simeq0.55$ of $1.53 {^{+0.28}_{-0.25}} {^{+0.32}_{-0.31}} 10^{-4} h^3 {\\rm Mpc}^{-3} {\\rm yr}^{-1}$ or $0.58 {^{+0.10}_{-0.09}} {^{+0.10}_{-0.09}} h^2 {\\rm SNu}$ (1 SNu = 1 supernova per century per $10^{10}$\\Lbsun), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models.

  12. THE GEOMORPHOSITES OF ROŞIA MONTANĂ

    Directory of Open Access Journals (Sweden)

    Maria-Adina Jurj

    2016-06-01

    Full Text Available The geomorphosites of Roșia Montană. The volcanic relief of the Roșia Montană mining area is characterised by a significant number of geomorphosites, represented especially by necks and dykes, such as: Cârnic, Orlea, Jig-Văidoaia, Lety etc. Another category of geomorphosites is represented by those with hydrographic features, namely the ponds created for mining purposes since Roman period. We identified a number of 14 geomorphosites; 9 of these are the results of the Neogene volcanic activity, and 5 are the ponds which appeared as an indirect consequence of the volcanic specific of the area. The geomorphosites created by the volcanic activity have also a significant archaeological, historical and cultural value, due to the valuable mining galleries and another evidences of this ancient activity. Among all the geomorphosites of the area, the most important one is Cârnic Massif which has a complex system of underground mining galleries, some of them belonging to Roman period. We consider that capitalization through touristic activities of these landforms is the best utilization in terms of ecological, cultural and economic perspectives.

  13. Finding Distances to Type Ia Supernovae

    Science.gov (United States)

    Kohler, Susanna

    2016-03-01

    Type Ia supernovae are known as standard candles due to their consistency, allowing us to measure distances based on their brightness. But what if these explosions arent quite as consistent as we thought? Due scientific diligence requires careful checks, so a recent study investigates whether the metallicity of a supernovas environment affects the peak luminosity of the explosion.Metallicity Dependence?Type Ia supernovae are incredibly powerful tools for determining distances in our universe. Because these supernovae are formed by white dwarfs that explode when they reach a uniform accreted mass, the supernova peak luminosity is thought to be very consistent. This consistency allows these supernovae to be used as standard candles to measure distances to their host galaxies.But what if that peak luminosity is affected by a factor that we havent taken into account? Theorists have proposed that the luminosities of Type Ia supernovae might depend on the metallicity of their environments with high-metallicity environments suppressing supernova luminosities. If this is true, then we could be systematically mis-measuring cosmological distances using these supernovae.Testing AbundancesSupernova brightnesses vs. the metallicity of their environments. Low-metallicity supernovae (blue shading) and high-metallicity supernovae (red shading) have an average magnitude difference of ~0.14. [Adapted from Moreno-Raya et al. 2016]A team led by Manuel Moreno-Raya, of the Center for Energy, Environment and Technology (CIEMAT) in Spain, has observed 28 Type Ia supernovae in an effort to test for such a metallicity dependence. These supernovae each have independent distance measurements (e.g., from Cepheids or the Tully-Fisher relation).Moreno-Raya and collaborators used spectra from the 4.2-m William Herschel Telescope to estimate oxygen abundances in the region where each of these supernovae exploded. They then used these measurements to determine if metallicity of the local region

  14. Inhibitory and Excitatory Spike-Timing-Dependent Plasticity in the Auditory Cortex

    Science.gov (United States)

    D'amour, James A.; Froemke, Robert C.

    2015-01-01

    Summary Synapses are plastic and can be modified by changes of spike timing. While most studies of long-term synaptic plasticity focus on excitation, inhibitory plasticity may be critical for controlling information processing, memory storage, and overall excitability in neural circuits. Here we examine spike-timing-dependent plasticity (STDP) of inhibitory synapses onto layer 5 neurons in slices of mouse auditory cortex, together with concomitant STDP of excitatory synapses. Pairing pre- and postsynaptic spikes potentiated inhibitory inputs irrespective of precise temporal order within ~10 msec. This was in contrast to excitatory inputs, which displayed an asymmetrical STDP time window. These combined synaptic modifications both required NMDA receptor activation, and adjusted the excitatory-inhibitory ratio of events paired together with postsynaptic spiking. Finally, subthreshold events became suprathreshold, and the time window between excitation and inhibition became more precise. These findings demonstrate that cortical inhibitory plasticity requires interactions with co-activated excitatory synapses to properly regulate excitatory-inhibitory balance. PMID:25843405

  15. Prefrontal NMDA receptors expressed in excitatory neurons control fear discrimination and fear extinction.

    Science.gov (United States)

    Vieira, Philip A; Corches, Alex; Lovelace, Jonathan W; Westbrook, Kevin B; Mendoza, Michael; Korzus, Edward

    2015-03-01

    N-methyl-D-aspartate receptors (NMDARs) are critically involved in various learning mechanisms including modulation of fear memory, brain development and brain disorders. While NMDARs mediate opposite effects on medial prefrontal cortex (mPFC) interneurons and excitatory neurons, NMDAR antagonists trigger profound cortical activation. The objectives of the present study were to determine the involvement of NMDARs expressed specifically in excitatory neurons in mPFC-dependent adaptive behaviors, specifically fear discrimination and fear extinction. To achieve this, we tested mice with locally deleted Grin1 gene encoding the obligatory NR1 subunit of the NMDAR from prefrontal CamKIIα positive neurons for their ability to distinguish frequency modulated (FM) tones in fear discrimination test. We demonstrated that NMDAR-dependent signaling in the mPFC is critical for effective fear discrimination following initial generalization of conditioned fear. While mice with deficient NMDARs in prefrontal excitatory neurons maintain normal responses to a dangerous fear-conditioned stimulus, they exhibit abnormal generalization decrement. These studies provide evidence that NMDAR-dependent neural signaling in the mPFC is a component of a neural mechanism for disambiguating the meaning of fear signals and supports discriminative fear learning by retaining proper gating information, viz. both dangerous and harmless cues. We also found that selective deletion of NMDARs from excitatory neurons in the mPFC leads to a deficit in fear extinction of auditory conditioned stimuli. These studies suggest that prefrontal NMDARs expressed in excitatory neurons are involved in adaptive behavior.

  16. Excitatory amino acid transporters: recent insights into molecular mechanisms, novel modes of modulation and new therapeutic possibilities

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Fahlke, Christoph; Bjørn-Yoshimoto, Walden Emil;

    2015-01-01

    The five excitatory amino acid transporters (EAAT1–5) mediating the synaptic uptake of the major excitatory neurotransmitter glutamate are differently expressed throughout the CNS and at the synaptic level. Although EAATs are crucial for normal excitatory neurotransmission, explorations into the ...... of EAATs and their intricate transport process, the novel approaches to pharmacological modulation of the transporters that have emerged, and interesting new perspectives in EAAT as drug targets proposed in recent years....

  17. Ten Months of Observations of the Possible Super-Chandrasekhar Mass Type Ia Supernova 2009dc

    CERN Document Server

    Silverman, Jeffrey M; Li, Weidong; Filippenko, Alexei V; Miller, Adam A; Poznanski, Dovi

    2010-01-01

    In this paper, we present and analyse optical photometry and spectra of the extremely luminous and slowly evolving Type Ia supernova (SN Ia) 2009dc, and offer evidence that it is a super-Chandrasekhar mass (SC) SN Ia and thus had a SC white dwarf (WD) progenitor. Optical spectra of SN 2007if, a similar object, are also shown. SN 2009dc had one of the most slowly evolving light curves ever observed for a SN Ia, with a rise time of ~23 days and Delta m_15(B) = 0.72 mag. We calculate a lower limit to the peak bolometric luminosity of ~2.1e43 erg/s, though the actual value is likely ~60% larger. Optical spectra of SN 2009dc and SN 2007if obtained near maximum brightness exhibit strong CII features (indicative of a significant amount of unburned material), and the post-maximum spectra are dominated by iron-group elements. All of our spectra of SN 2009dc and SN 2007if also show low expansion velocities. The high luminosity and low expansion velocities of SN 2009dc lead us to derive a possible WD progenitor mass of ...

  18. Type Ia Supernova Colors and Ejecta Velocities: Hierarchical Bayesian Regression with Non-Gaussian Distributions

    CERN Document Server

    Mandel, Kaisey S; Kirshner, Robert P

    2014-01-01

    We investigate the correlations between the peak intrinsic colors of Type Ia supernovae (SN Ia) and their expansion velocities at maximum light, measured from the Si II 6355 A spectral feature. We construct a new hierarchical Bayesian regression model and Gibbs sampler to estimate the dependence of the intrinsic colors of a SN Ia on its ejecta velocity, while accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust. The method is applied to the apparent color data from BVRI light curves and Si II velocity data for 79 nearby SN Ia. Comparison of the apparent color distributions of high velocity (HV) and normal velocity (NV) supernovae reveals significant discrepancies in B-V and B-R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B-band, rather than dust reddening. The mean intrinsic B-V and B-R color differences between HV and NV groups are 0.06 +/- 0.02 and 0.09 +/- 0.02 mag, respectively. Under a linear m...

  19. Supernova 2010ev: A reddened high velocity gradient type Ia supernova

    CERN Document Server

    Gutiérrez, Claudia P; Folatelli, Gastón; Pignata, Giuliano; Anderson, Joseph P; Hamuy, Mario; Morrell, Nidia; Stritzinger, Maximilian; Taubenberger, Stefan; Bufano, Filomena; Olivares, Felipe E; Haislip, Joshua B; Reichart, Daniel E

    2016-01-01

    Aims. We present and study the spectroscopic and photometric evolution of the type Ia supernova (SN Ia) 2010ev. Methods. We obtain and analyze multi-band optical light curves and optical-near-infrared spectroscopy at low and medium resolution spanning from -7 days to +300 days from the B-band maximum. Results. A photometric analysis shows that SN 2010ev is a SN Ia of normal brightness with a light curve shape of $\\Delta m_{15}(B)=1.12 \\pm 0.02$ and a stretch s = $0.94 \\pm 0.01$ suffering significant reddening. From photometric and spectroscopic analysis, we deduce a color excess of $E(B - V) = 0.25 \\pm 0.05$ and a reddening law of $R_v = 1.54 \\pm 0.65$. Spectroscopically, SN 2010ev belongs to the broad-line SN Ia group, showing stronger than average Si II {\\lambda}6355 absorption features. We also find that SN 2010ev is a high-velocity gradient SN, with a value of $164 \\pm 7$ km s$^{-1}$ d$^{-1}$. The photometric and spectral comparison with other supernovae shows that SN 2010ev has similar colors and velocit...

  20. Measuring cosmic bulk flows with Type Ia Supernovae from the Nearby Supernova Factory

    CERN Document Server

    Feindt, U; Kowalski, M; Aldering, G; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Cellier-Holzem, F; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Guy, J; Kim, A; Nugent, P; Nordin, J; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Runge, K; Saunders, C; Scalzo, R; Smadja, G; Tao, C; Thomas, R C; Weaver, B A; Wu, C

    2013-01-01

    Context. Our Local Group of galaxies appears to be moving relative to the Cosmic Microwave Background with the source of the peculiar motion still uncertain. While in the past this has been studied mostly using galaxies as distance indicators, the weight of type Ia supernovae (SNe Ia) has increased recently with the continuously improving statistics of available low-redshift supernovae. Aims. We measured the bulk flow in the nearby universe (0.015 < z < 0.1) using 117 SNe Ia observed by the Nearby Supernova Factory, as well as the Union2 compilation of SN Ia data already in the literature. Methods. The bulk flow velocity was determined from SN data binned in redshift shells by including a coherent motion (dipole) in a cosmological fit. Additionally, a method of spatially smoothing the Hubble residuals was used to verify the results of the dipole fit. To constrain the location and mass of a potential mass concentration (e.g. the Shapley Supercluster) responsible for the peculiar motion, we fit a Hubble l...

  1. Adenosine Inhibits the Excitatory Synaptic Inputs to Basal Forebrain Cholinergic, GABAergic and Parvalbumin Neurons in mice

    Directory of Open Access Journals (Sweden)

    Chun eYang

    2013-06-01

    Full Text Available Coffee and tea contain the stimulants caffeine and theophylline. These compounds act as antagonists of adenosine receptors. Adenosine promotes sleep and its extracellular concentration rises in association with prolonged wakefulness, particularly in the basal forebrain (BF region involved in activating the cerebral cortex. However, the effect of adenosine on identified BF neurons, especially non-cholinergic neurons, is incompletely understood. Here we used whole-cell patch-clamp recordings in mouse brain slices prepared from two validated transgenic mouse lines with fluorescent proteins expressed in GABAergic or parvalbumin (PV neurons to determine the effect of adenosine. Whole-cell recordings were made BF cholinergic neurons and from BF GABAergic & PV neurons with the size (>20 µm and intrinsic membrane properties (prominent H-currents corresponding to cortically projecting neurons. A brief (2 min bath application of adenosine (100 μM decreased the frequency but not the amplitude of spontaneous excitatory postsynaptic currents in all groups of BF cholinergic, GABAergic and PV neurons we recorded. In addition, adenosine decreased the frequency of miniature EPSCs in BF cholinergic neurons. Adenosine had no effect on the frequency of spontaneous inhibitory postsynaptic currents in cholinergic neurons or GABAergic neurons with large H-currents but reduced them in a group of GABAergic neurons with smaller H-currents. All effects of adenosine were blocked by a selective, adenosine A1 receptor antagonist, cyclopentyltheophylline (CPT, 1 μM. Adenosine had no postsynaptic effects. Taken together, our work suggests that adenosine promotes sleep by an A1-receptor mediated inhibition of glutamatergic inputs to cortically-projecting cholinergic and GABA/PV neurons. Conversely, caffeine and theophylline promote attentive wakefulness by inhibiting these A1 receptors in BF thereby promoting the high-frequency oscillations in the cortex required for

  2. Neural signal transduction aided by noise in multisynaptic excitatory and inhibitory pathways with saturation

    Science.gov (United States)

    Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

    2011-08-01

    We study the stochastic resonance phenomenon in saturating dynamical models of neural signal transduction, at the synaptic stage, wherein the noise in multipathways enhances the processing of neuronal information integrated by excitatory and inhibitory synaptic currents. For an excitatory synaptic pathway, the additive intervention of an inhibitory pathway reduces the stochastic resonance effect. However, as the number of synaptic pathways increases, the signal transduction is greatly improved for parallel multipathways that feature both excitation and inhibition. The obtained results lead us to the realization that the collective property of inhibitory synapses assists neural signal transmission, and a parallel array of neurons can enhance their responses to multiple synaptic currents by adjusting the contributions of excitatory and inhibitory currents.

  3. UBVRI Light Curves of 44 Type Ia Supernovae

    NARCIS (Netherlands)

    Jha, Saurabh; Groot, Paul J.

    2006-01-01

    We present UBVRI photometry of 44 Type Ia supernovae (SNe Ia) observed from 1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The data set comprises 2190 observations and is the largest homogeneously

  4. The Connection between IAS/IFRS and Social Responsibility

    Directory of Open Access Journals (Sweden)

    Stefano AMELIO

    2016-05-01

    Full Text Available The aim of the paper is to evaluate the degree of social responsibility arising from the statement of comprehensive income prepared according to IAS/IFRS, to demonstrate whether the values obtained from prospects and from the calculation of the indicators are sufficient to analyze the Company's performance from the perspective of social responsibility and sustainable value or not. In order to achieve the objective of harmonization, the European Union adopted the IAS/IFRS developed by the International Accounting Standards Board (IASB. The research is divided into two sections and the approach used is mainly theoretical and qualitative. In the first part, the financial statements to be prepared according to IAS 1 and IAS 7 and, in particular, the so called statement of profit or loss and other comprehensive income for the period are analyzed by underling the function of the same and by presenting some financial performance indicators. Then, the research highlights how these values obtained are not useful to communicate the company's strategy in terms of social responsibility and sustainable value. In the second part the analyses exposes the concept of social balance. According to the social responsibility view the IAS/IFRS financial statements should be accompanied by the social balance. It becomes crucial to complete the set of financial statements stated from IAS 1 with a social balance as well as the same IAS 1 contemplates. For this reason it is possible to say that the connection between IAS/IFRS and social responsibility is weak.

  5. Autologous peptides constitutively occupy the antigen binding site on Ia

    DEFF Research Database (Denmark)

    Buus, S; Sette, A; Colon, S M;

    1988-01-01

    Low molecular weight material associated with affinity-purified class II major histocompatibility complex (MHC) molecules of mouse (Ia) had the expected properties of peptides bound to the antigen binding site of Ia. Thus, the low molecular weight material derived from the I-Ad isotype...

  6. 77 FR 66067 - Amendment of Class E Airspace; Boone, IA

    Science.gov (United States)

    2012-11-01

    ... Administration 14 CFR Part 71 Amendment of Class E Airspace; Boone, IA AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action amends Class E airspace at Boone, IA... necessary for standard instrument approach procedures and for the safety and management of Instrument...

  7. 77 FR 68682 - Amendment of Class E Airspace; Guthrie, IA

    Science.gov (United States)

    2012-11-16

    ... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Guthrie, IA AGENCY: Federal... Guthrie, IA. Decommissioning of the Guthrie Center non-directional radio beacon (NDB) at Guthrie County... safety and management of Instrument Flight Rule (IFR) operations at the airport. Geographic...

  8. Spatial patterning of excitatory and inhibitory neuropil territories during spinal circuit development.

    Science.gov (United States)

    Yan, Qing; Zhai, Lu; Zhang, Bo; Dallman, Julia E

    2017-05-01

    To generate rhythmic motor behaviors, both single neurons and neural circuits require a balance between excitatory inputs that trigger action potentials and inhibitory inputs that promote a stable resting potential (E/I balance). Previous studies have focused on individual neurons and have shown that, over a short spatial scale, excitatory and inhibitory (E/I) synapses tend to form structured territories with inhibitory inputs enriched on cell bodies and proximal dendrites and excitatory inputs on distal dendrites. However, systems-level E/I patterns, at spatial scales larger than single neurons, are largely uncharted. We used immunostaining for PSD-95 and gephyrin postsynaptic scaffolding proteins as proxies for excitatory and inhibitory synapses, respectively, to quantify the numbers and map the distributions of E/I synapses in zebrafish spinal cord at both an embryonic stage and a larval stage. At the embryonic stage, we found that PSD-95 puncta outnumber gephyrin puncta, with the number of gephyrin puncta increasing to match that of PSD-95 puncta at the larval stage. At both stages, PSD-95 puncta are enriched in the most lateral neuropil corresponding to distal dendrites while gephyrin puncta are enriched on neuronal somata and in the medial neuropil. Significantly, similar to synaptic puncta, neuronal processes also exhibit medial-lateral territories at both developmental stages with enrichment of glutamatergic (excitatory) processes laterally and glycinergic (inhibitory) processes medially. This establishment of neuropil excitatory-inhibitory structure largely precedes dendritic arborization of primary motor neurons, suggesting that the structured neuropil could provide a framework for the development of E/I balance at the cellular level. J. Comp. Neurol. 525:1649-1667, 2017. © 2016 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  9. Intermediate-band Photometry of Type Ia Supernovae

    CERN Document Server

    Wang, X; Zhang, T; Li, Z; Wang, Xiaofeng; Zhou, Xu; Zhang, Tianmeng; Li, Zongwei

    2004-01-01

    We present optical light curves of five Type Ia supernovae (2002er, 2002fk, 2003cg, 2003du, 2003fk). The photometric observations were performed in a set of intermediate-band filters. SNe 2002er, 2003du appear to be normal SN Ia events with similar light curve shapes, while SN 2003kf shows the behavior of a brighter SN Ia with slower decline rate after maximum. The light curves of SN 2003cg is unusual; they show a fast rise and dramatic decline near maximum and do not display secondary peak at longer wavelengths during 15-30 days after maximum light. This suggests that SN 2003cg is likely to be an intrinsically subluminous, 91bg-like SN Ia. Exploration of SN Ia feature lines through intermediate-band photometry is briefly discussed.

  10. Theoretical considerations about implementation of IAS 41 in Romania

    Directory of Open Access Journals (Sweden)

    Liliana FELEAGĂ

    2012-02-01

    Full Text Available Although agriculture is an important part of the world economy, accounting in agriculture still has many shortcomings. The adoption of IAS 41 „Agricuture” has tried to improve this situation and increase the comparability of financial statements of entities in the agricultural sector. Although controversial, IAS 41 is the first step of a consistent transition to fair value assessment in the agricultural sector. The objective of our work is the analysis of IAS 41 and current accounting agricultural situation in Romania. Accounting regulations in Romania are in accordance with European directives and, in many respects, converged with IFRS referential. Provisions of IAS 41, however, are not reflected directly in Romanian regulations. With the increase of forest land transactions and foreign investments in animal farms, it is expected that recognition and measurement of biological assets under IAS 41 to become a necessity.

  11. Type Ia Supernova Remnants: Shaping by Iron Bullets

    CERN Document Server

    Tsebrenko, Danny

    2015-01-01

    Using 2D numerical hydrodynamical simulations of type Ia supernova remnants (SNR Ia) we show that iron clumps few times denser than the rest of the SN ejecta might form protrusions in an otherwise spherical SNR. Such protrusions exist in some SNR Ia, e.g., SNR 1885 and Tycho. Iron clumps are expected to form in the deflagration to detonation explosion model. In SNR Ia where there are two opposite protrusions, termed ears, such as Kepler's SNR and SNR G1.9+0.3, our scenario implies that the dense clumps, or iron bullets, were formed along an axis. Such a preferred axis can result from a rotating white dwarf progenitor. If our claim holds, this offers an important clue to the SN Ia explosion scenario.

  12. Human Ia-like antigens in non-lymphoid organs.

    Science.gov (United States)

    Koyama, K; Fukunishi, T; Barcos, M; Tanigaki, N; Pressman, D

    1979-01-01

    Human Ia-like antigens in liver and kidney were shown by the immunofluorescence assay to be present mostly in the endothelial-mesenchymal cells of these organs. The parenchymal cells apparently contained no human Ia-like antigens. The antigens in liver and kidney were purified and shown to have the same subunit structure as human Ia-like antigens of cultured B-lymphoid cells. The human Ia-like antigens in non-lymphoid organs, not only in liver and kidney but also in testis, heart, muscle and brain, carried all the xenoantigenic characteristics of human Ia-like antigens expressed on lymphoid cells of B-cell lineage. Images Figure 1 PMID:389786

  13. Adiponectin levels correlate with the severity of hypertriglyceridaemia in glycogen storage disease Ia

    NARCIS (Netherlands)

    Bandsma, R. H. J.; Smit, G. P. A.; Reijngoud, D. -J.; Kuipers, F.

    2009-01-01

    Glycogen storage disease type Ia (GSD Ia) is characterized by severe hypercholesterolaemia and hypertriglyceridaemia. Little is known about the aetiology of the hyperlipidaemia in GSD Ia. Adipokines play an important regulatory role in lipid metabolism. We investigated whether adipokine concentratio

  14. Bistability Analysis of Excitatory-Inhibitory Neural Networks in Limited-Sustained-Activity Regime

    Institute of Scientific and Technical Information of China (English)

    倪赟; 吴亮; 吴丹; 朱士群

    2011-01-01

    Bistable behavior of neuronal complex networks is investigated in the limited-sustained-activity regime when the network is composed of excitatory and inhibitory neurons. The standard stability analysis is performed on the two metastable states separately. Both theoretical analysis and numerical simulations show consistently that the difference between time scales of excitatory and inhibitory populations can influence the dynamical behaviors of the neuronal networks dramatically, leading to the transition from bistable behaviors with memory effects to the collapse of bistable behaviors. These results may suggest one possible neuronal information processing by only tuning time scales.

  15. The importance of the excitatory amino acid transporter 3 (EAAT3)

    DEFF Research Database (Denmark)

    E. Bjørn-Yoshimoto, Walden; Underhill, Suzanne M.

    2016-01-01

    Abstract The neuronal excitatory amino acid transporter 3 (EAAT3) is fairly ubiquitously expressed in the brain, though it does not necessarily maintain the same function everywhere. It is important in maintaining low local concentrations of glutamate, where its predominant post-synaptic localiza......Abstract The neuronal excitatory amino acid transporter 3 (EAAT3) is fairly ubiquitously expressed in the brain, though it does not necessarily maintain the same function everywhere. It is important in maintaining low local concentrations of glutamate, where its predominant post...

  16. Anastilosis Virtual de Felipéia

    Directory of Open Access Journals (Sweden)

    Hélio Costa Lima

    2011-04-01

    Full Text Available This text is about a virtual anastylosis of Felipéia, capital of Paraíba, the first city founded in Brazil under the Spanish Crown in 1585, during the Iberic Union. Recently, infographics resources enabled the reconstruction, with great precision, of the old city’s ground plans from Dutch maps from 1634-37, and establish the first hypothesis of a tridimensional configuration of the city. Now, measuring and studies are being done to make possible a piece by piece virtual anastylosis of the buildings and, after that, a tridimensional virtual reconstruction of the historical city, which will enable virtual walkabouts on the streets, squares and buildings.

  17. Type Ia Supernova Explosion: Gravitationally Confined Detonation

    CERN Document Server

    Plewa, T; Lamb, D

    2004-01-01

    We present a new mechanism for Type Ia supernova explosions in massive white dwarfs. The proposed scenario follows from relaxing the assumption of symmetry in the model and involves a detonation created in an unconfined environment. The explosion begins with an essentially central ignition of stellar material initiating a deflagration. This deflagration results in the formation of a buoyantly-driven bubble of hot material that reaches the stellar surface at supersonic speeds. The bubble breakout forms a strong pressure wave that laterally accelerates fuel-rich outer stellar layers. This material, confined by gravity to the white dwarf, races along the stellar surface and is focused at the location opposite to the point of the bubble breakout. These streams of nuclear fuel carry enough mass and energy to trigger a detonation just above the stellar surface. The flow conditions at that moment support a detonation that will incinerate the white dwarf and result in an energetic explosion. The stellar expansion fol...

  18. Type Ia supernovae and the DD scenario

    CERN Document Server

    Isern, J; Lorén-Aguilar, P

    2011-01-01

    Type Ia supernovae are thought to be the outcome of the thermonuclear explosion of a white dwarf in a close binary system. Two possible scenarios, not necessarily incompatible, have been advanced. One assumes a white dwarf that accretes matter from a nondegenerate companion (the single degenerate scenario), the other assumes two white dwarfs that merge as a consequence of the emission of gravitational waves (the double degenerate scenario). The delay time distribution of star formation bursts strongly suggests that the DD scenario should be responsible of the late time explosions, but this contradicts the common wisdom that the outcome of the merging of two white dwarfs is an accretion induced collapse to a neutron star. In this contribution we review some of the most controversial issues of this problem.

  19. Phases of a Type Ia supernova explosion

    CERN Document Server

    Niemeyer, J C

    1998-01-01

    In the framework of the Chandrasekhar mass white dwarf model for Type Ia supernovae, various stages of the explosion are described in terms of the burning regimes of the thermonuclear flame front. In the early flamelet regime following the ``smoldering'' phase prior to the explosion, the flame is sufficiently thin and fast to remain laminar on small scales. As the white dwarf density declines, the thermal flame structure becomes subject to penetration by turbulent eddies, and it enters the ``distributed burning'' regime. A specific control parameter for this transition is proposed. Furthermore, we outline an argument for the coincidence of the transition between burning regimes with the onset of a deflagration-detonation-transition (DDT) in the late phase of the explosion.

  20. 3IA Conference (3IA’2011)

    CERN Document Server

    Miaoulis, Georgios; Intelligent Computer Graphics 2011

    2012-01-01

    In Computer Graphics, the use of intelligent techniques started more recently than in other research areas. However, during these last two decades, the use of intelligent Computer Graphics techniques is growing up year after year and more and more interesting techniques are presented in this area.   The purpose of this volume is to present current work of the Intelligent Computer Graphics community, a community growing up year after year. This volume is a kind of continuation of the previously published Springer volumes “Artificial Intelligence Techniques for Computer Graphics” (2008), “Intelligent Computer Graphics 2009” (2009) and “Intelligent Computer Graphics 2010” (2010).   This volume contains selected extended papers from the last 3IA Conference (3IA’2011), which has been held in Athens (Greece) in May 2011. This year papers are particularly exciting and concern areas like virtual reality, artificial life, data visualization, games, global illumination, point cloud modelling, declarativ...

  1. Expression of an insect excitatory toxin, BmK IT, from the scorpion, Buthus martensii Karsch, and its biological activity.

    Science.gov (United States)

    Hao, Chan-juan; Xu, Cheng-gang; Wang, Wei; Chai, Bao-feng; Liang, Ai-hua

    2005-12-01

    An insect excitatory toxin from Buthus martensii Karsch (BmK IT) was cloned into the expression vector, pTWIN1, and expressed into Escherichia coli BL21 (DE3) host cells. The soluble fusion expression of CBD-intein-BmK IT was obtained. The recombinant BmK IT was purified by two anion-exchange chromatography columns and one gel chromatography column. Bioassays were carried out to verify the toxicity of this recombinant toxin. At the end of a 96 h experimental period, 83% of cotton bollworm larvae were killed with an LT(50) value of 58-62 h. Furthermore, the average weight of larvae fed on BmK IT-containing media was approx 4% of that of the control groups. The results indicate that the expressed and purified recombinant BmK IT has biological activity.

  2. Cocaine cues retain silent traces of an excitatory history after conversion into conditioned inhibitors: 'the ghost in the addict'.

    Science.gov (United States)

    Weiss, Stanley J; Kearns, David N

    2016-04-01

    The present experiment investigated the extent to which the A+/AB- conditioned inhibition procedure could counteract an excitatory drug-related conditioning history. In two groups of rats, a light stimulus was established as a signal for the absence of cocaine. For the History group, the light had previously been a discriminative stimulus (S) that occasioned cocaine self-administration and could thus be classified as a cocaine excitor. In comparison, the No-History group first encountered the light during conditioned inhibition training. During conditioned inhibition training, both groups self-administered cocaine during tone as well as during click Ss, whereas drug seeking was eliminated in click-plus-light, wherein cocaine was not available (A+/AB-). Drug seeking was essentially eliminated in both groups. Nevertheless, on a summation test the light reduced cocaine seeking occasioned by the tone S by 95% in the No-History group, but by less than 50% in the History group. This summation test result showed that the effects of a drug-related history persisted even after the light was converted into an effective conditioned inhibitor on the training baseline through the powerful A+/AB- procedure. Future research should seek procedures that produce even stronger conditioned inhibition that eliminates such residual 'silent' drug excitation, the 'ghost in the addict'.

  3. 78 FR 13015 - Designation for the Sandusky, MI; Davenport, IA; Enid, OK; Keokuk, IA; Marshall, MI; and Omaha...

    Science.gov (United States)

    2013-02-26

    ... the September 13, 2012 Federal Register (77 FR 56608), GIPSA requested applications for designation to... Grain Inspection, Packers and Stockyards Administration Designation for the Sandusky, MI; Davenport, IA; Enid, OK; Keokuk, IA; Marshall, MI; and Omaha, NE Areas AGENCY: Grain Inspection, Packers...

  4. Exploring the spectroscopic diversity of Type Ia supernovae with DRACULA: a machine learning approach

    Science.gov (United States)

    Sasdelli, M.; Ishida, E. E. O.; Vilalta, R.; Aguena, M.; Busti, V. C.; Camacho, H.; Trindade, A. M. M.; Gieseke, F.; de Souza, R. S.; Fantaye, Y. T.; Mazzali, P. A.

    2016-09-01

    The existence of multiple subclasses of Type Ia supernovae (SNe Ia) has been the subject of great debate in the last decade. One major challenge inevitably met when trying to infer the existence of one or more subclasses is the time consuming, and subjective, process of subclass definition. In this work, we show how machine learning tools facilitate identification of subtypes of SNe Ia through the establishment of a hierarchical group structure in the continuous space of spectral diversity formed by these objects. Using deep learning, we were capable of performing such identification in a four-dimensional feature space (+1 for time evolution), while the standard principal component analysis barely achieves similar results using 15 principal components. This is evidence that the progenitor system and the explosion mechanism can be described by a small number of initial physical parameters. As a proof of concept, we show that our results are in close agreement with a previously suggested classification scheme and that our proposed method can grasp the main spectral features behind the definition of such subtypes. This allows the confirmation of the velocity of lines as a first-order effect in the determination of SN Ia subtypes, followed by 91bg-like events. Given the expected data deluge in the forthcoming years, our proposed approach is essential to allow a quick and statistically coherent identification of SNe Ia subtypes (and outliers). All tools used in this work were made publicly available in the PYTHON package Dimensionality Reduction And Clustering for Unsupervised Learning in Astronomy (DRACULA) and can be found within COINtoolbox (https://github.com/COINtoolbox/DRACULA).

  5. TYPE Ia SUPERNOVA COLORS AND EJECTA VELOCITIES: HIERARCHICAL BAYESIAN REGRESSION WITH NON-GAUSSIAN DISTRIBUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mandel, Kaisey S.; Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Foley, Ryan J., E-mail: kmandel@cfa.harvard.edu [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)

    2014-12-20

    We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10{sup 3} km s{sup –1}){sup –1} for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A{sub V} extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances.

  6. Neurotransmitter alterations in embryonic succinate semialdehyde dehydrogenase (SSADH deficiency suggest a heightened excitatory state during development

    Directory of Open Access Journals (Sweden)

    Snead O Carter

    2008-11-01

    Full Text Available Abstract Background SSADH (aldehyde dehydrogenase 5a1 (Aldh5a1; γ-hydroxybutyric (GHB aciduria deficiency is a defect of GABA degradation in which the neuromodulators GABA and GHB accumulate. The human phenotype is that of nonprogressive encephalopathy with prominent bilateral discoloration of the globi pallidi and variable seizures, the latter displayed prominently in Aldh5a1-/- mice with lethal convulsions. Metabolic studies in murine neural tissue have revealed elevated GABA [and its derivatives succinate semialdehyde (SSA, homocarnosine (HC, 4,5-dihydroxyhexanoic acid (DHHA and guanidinobutyrate (GB] and GHB [and its analogue D-2-hydroxyglutarate (D-2-HG] at birth. Because of early onset seizures and the neurostructural anomalies observed in patients, we examined metabolite features during Aldh5a1-/- embryo development. Methods Embryos were obtained from pregnant dams sacrificed at E (embryo day of life 10–13, 14–15, 16–17, 18–19 and newborn mice. Intact embryos were extracted and metabolites quantified by isotope dilution mass spectrometry (n = 5–15 subjects, Aldh5a1+/+ and Aldh5a1-/- for each gestational age group. Data was evaluated using the t test and one-way ANOVA with Tukey post hoc analysis. Significance was set at the 95th centile. Results GABA and DHHA were significantly elevated at all gestational ages in Aldh5a1-/- mice, while GB was increased only late in gestation; SSA was not elevated at any time point. GHB and D-2-HG increased in an approximately linear fashion with gestational age. Correlative studies in human amniotic fluid from SSADH-deficient pregnancies (n = 5 also revealed significantly increased GABA. Conclusion Our findings indicate early GABAergic alterations in Aldh5a1-/- mice, possibly exacerbated by other metabolites, which likely induce a heightened excitatory state that may predispose neural networks to epilepsy in these animals.

  7. How to Find Gravitationally Lensed Type Ia Supernovae

    CERN Document Server

    Goldstein, Daniel A

    2016-01-01

    Type Ia supernovae (SNe Ia) that are multiply imaged by gravitational lensing can extend the SN Ia Hubble diagram to very high redshifts ($z\\gtrsim 2$), probe potential SN Ia evolution, and deliver high-precision constraints on $H_0$, $w$, and $\\Omega_m$ via time delays. However, only one, iPTF16geu, has been found to date, and many more are needed to achieve these goals. To increase the multiply imaged SN Ia discovery rate we present a simple algorithm for identifying gravitationally lensed SN Ia candidates in cadenced, wide-field optical imaging surveys. The technique is to look for supernovae that appear to have an elliptical galaxy as their host with an absolute magnitude implied by the host's photometric redshift that is far brighter than the absolute magnitude of a normal SN Ia (the brightest type of supernova found in elliptical galaxies). Importantly, this purely photometric method does not require the ability to resolve the lensed images for discovery. The primary sources of contamination that affect...

  8. K-corrections and spectral templates of Type Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, Peter E; Hsiao, E.Y.; Conley, A.; Howell, D.A.; Sullivan, M.; Pritchet, C.J.; Carlberg, R.G.; Nugent, P.E.; Phillips, M.M.

    2007-03-20

    With the advent of large dedicated Type Ia supernova (SN Ia) surveys, K-corrections of SNe Ia and their uncertainties have become especially important in the determination of cosmological parameters. While K-corrections are largely driven by SN Ia broadband colors, it is shown here that the diversity in spectral features of SNe Ia can also be important. For an individual observation, the statistical errors from the inhomogeneity in spectral features range from 0.01 (where the observed and rest-frame filters are aligned) to 0.04 (where the observed and rest-frame filters are misaligned). To minimize the systematic errors caused by an assumed SN Ia spectral energy distribution (SED), we outline a prescription for deriving a mean spectral template time series that incorporates a large and heterogeneous sample of observed spectra. We then remove the effects of broadband colors and measure the remaining uncertainties in the K-corrections associated with the diversity in spectral features. Finally, we present a template spectroscopic sequence near maximum light for further improvement on the K-correction estimate. A library of ~;;600 observed spectra of ~;;100 SNe Ia from heterogeneous sources is used for the analysis.

  9. Photometric selection of high-redshift type Ia supernovae

    CERN Document Server

    Sullivan, M; Perrett, K; Nugent, P; Astier, Pierre; Aubourg, E; Balam, D; Basa, S; Carlberg, R; Conley, A; Fabbro, S; Fouchez, D; Guy, J; Hook, I; Lafoux, H; Neill, J D; Pain, R; Palanque-Delabrouille, Nathalie; Pritchet, C; Regnault, N; Rich, J; Taillet, R; Aldering, G; Baumont, S; Bronder, J; Filiol, M; Knop, R; Perlmutter, S; Tao, C

    2005-01-01

    We present a method for selecting high-redshift type Ia supernovae (SNe Ia) located via rolling SN searches. The technique, using both color and magnitude information of events from only 2-3 epochs of multi-band real-time photometry, is able to discriminate between SNe Ia and core collapse SNe. Furthermore, for the SNe Ia, the method accurately predicts the redshift, phase and light-curve parameterization of these events based only on pre-maximum-light data. We demonstrate the effectiveness of the technique on a simulated survey of SNe Ia and core-collapse SNe, where the selection method effectively rejects most core-collapse SNe while retaining SNe Ia. We also apply the selection code to real-time data acquired as part of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). During the period May 2004 to January 2005 in the SNLS, 440 SN candidates were discovered of which 70 were confirmed spectroscopically as SNe Ia and 15 as core-collapse events. For this test dataset, the selection technique ...

  10. Excitatory effects of Buthus C56 toxin on Drosophila larval neuromuscular junction

    Directory of Open Access Journals (Sweden)

    S. P. Gawade

    2003-01-01

    Full Text Available Buthus C56 toxin from venom of the Indian red scorpion Mesobuthus tamulus was studied for its effects on spontaneous miniature excitatory junctional potentials (MEJP on Drosophila larval neuromuscular junctions. C56 toxin was isolated on CM-Cellulose with linear gradient of ammonium acetate buffer, pH 6.0. Toxin purity was determined on SDS slab gel electrophoresis. Effective concentration of C56 toxin was based on contraction paralysis units (CPU in Drosophila 3rd instar larvae by microinjection (0.1 CPU/ml = 2 x 10-6 g/ml. The toxin-induced excitatory junctional potentials were studied for calcium dependency (0.2 mM to 1.2 mM Ca2+ in Drosophila Ringer. Excitatory junctional potential amplitude was increased with increasing calcium concentration; maximum increase in the frequency at 0.4 mM Ca2+/4 mM Mg2+ Drosophila Ringer. It was suggested that while amplitude of excitatory junctional potentials was increased with concentration, maximum frequency increase at 0.4 mMCa2+/4 mM Mg2+ Drosophila Ringer may be due to augmented Ca2+ influx in 0.4 mM Ca2+, when NMDA receptors were maximally activated in C56 toxin-treated Drosophila larval neuromuscular junction.

  11. Transient oxytocin signaling primes the development and function of excitatory hippocampal neurons

    Science.gov (United States)

    Ripamonti, Silvia; Ambrozkiewicz, Mateusz C; Guzzi, Francesca; Gravati, Marta; Biella, Gerardo; Bormuth, Ingo; Hammer, Matthieu; Tuffy, Liam P; Sigler, Albrecht; Kawabe, Hiroshi; Nishimori, Katsuhiko; Toselli, Mauro; Brose, Nils; Parenti, Marco; Rhee, JeongSeop

    2017-01-01

    Beyond its role in parturition and lactation, oxytocin influences higher brain processes that control social behavior of mammals, and perturbed oxytocin signaling has been linked to the pathogenesis of several psychiatric disorders. However, it is still largely unknown how oxytocin exactly regulates neuronal function. We show that early, transient oxytocin exposure in vitro inhibits the development of hippocampal glutamatergic neurons, leading to reduced dendrite complexity, synapse density, and excitatory transmission, while sparing GABAergic neurons. Conversely, genetic elimination of oxytocin receptors increases the expression of protein components of excitatory synapses and excitatory synaptic transmission in vitro. In vivo, oxytocin-receptor-deficient hippocampal pyramidal neurons develop more complex dendrites, which leads to increased spine number and reduced γ-oscillations. These results indicate that oxytocin controls the development of hippocampal excitatory neurons and contributes to the maintenance of a physiological excitation/inhibition balance, whose disruption can cause neurobehavioral disturbances. DOI: http://dx.doi.org/10.7554/eLife.22466.001 PMID:28231043

  12. Imperfect space clamp permits electrotonic interactions between inhibitory and excitatory synaptic conductances, distorting voltage clamp recordings.

    Directory of Open Access Journals (Sweden)

    Alon Poleg-Polsky

    Full Text Available The voltage clamp technique is frequently used to examine the strength and composition of synaptic input to neurons. Even accounting for imperfect voltage control of the entire cell membrane ("space clamp", it is often assumed that currents measured at the soma are a proportional indicator of the postsynaptic conductance. Here, using NEURON simulation software to model somatic recordings from morphologically realistic neurons, we show that excitatory conductances recorded in voltage clamp mode are distorted significantly by neighboring inhibitory conductances, even when the postsynaptic membrane potential starts at the reversal potential of the inhibitory conductance. Analogous effects are observed when inhibitory postsynaptic currents are recorded at the reversal potential of the excitatory conductance. Escape potentials in poorly clamped dendrites reduce the amplitude of excitatory or inhibitory postsynaptic currents recorded at the reversal potential of the other conductance. In addition, unclamped postsynaptic inhibitory conductances linearize the recorded current-voltage relationship of excitatory inputs comprising AMPAR and NMDAR-mediated components, leading to significant underestimation of the relative contribution by NMDARs, which are particularly sensitive to small perturbations in membrane potential. Voltage clamp accuracy varies substantially between neurons and dendritic arbors of different morphology; as expected, more reliable recordings are obtained from dendrites near the soma, but up to 80% of the synaptic signal on thin, distant dendrites may be lost when postsynaptic interactions are present. These limitations of the voltage clamp technique may explain how postsynaptic effects on synaptic transmission could, in some cases, be attributed incorrectly to presynaptic mechanisms.

  13. Excitatory amino acid receptors in the ventral tegmental area regulate dopamine release in the ventral striatum

    NARCIS (Netherlands)

    Karreman, M; Westerink, BHC; Moghaddam, B

    1996-01-01

    The role of excitatory amino acid (EAA) receptors located in the ventral tegmental area (VTA) in tonic and phasic regulation of dopamine release in the ventral striatum was investigated. Microdialysis in conscious rats was used to assess dopamine release primarily from the nucleus accumbens shell re

  14. Retinal Physiology: Non-Bipolar-Cell Excitatory Drive in the Inner Retina.

    Science.gov (United States)

    Baden, Tom; Euler, Thomas

    2016-08-01

    The long-held view that bipolar cells provide the exclusive excitatory drive to the mammalian inner retina has been challenged: new studies indicate that, instead, at least two cells that lack the dendrites characteristic for bipolar cells, and therefore resemble amacrine cells, excite inner retinal circuits using glutamate.

  15. Neuronal pentraxin 1 negatively regulates excitatory synapse density and synaptic plasticity.

    Science.gov (United States)

    Figueiro-Silva, Joana; Gruart, Agnès; Clayton, Kevin Bernard; Podlesniy, Petar; Abad, Maria Alba; Gasull, Xavier; Delgado-García, José María; Trullas, Ramon

    2015-04-08

    In mature neurons, the number of synapses is determined by a neuronal activity-dependent dynamic equilibrium between positive and negative regulatory factors. We hypothesized that neuronal pentraxin (NP1), a proapoptotic protein induced by low neuronal activity, could be a negative regulator of synapse density because it is found in dystrophic neurites in Alzheimer's disease-affected brains. Here, we report that knockdown of NP1 increases the number of excitatory synapses and neuronal excitability in cultured rat cortical neurons and enhances excitatory drive and long-term potentiation in the hippocampus of behaving mice. Moreover, we found that NP1 regulates the surface expression of the Kv7.2 subunit of the Kv7 family of potassium channels that control neuronal excitability. Furthermore, pharmacological activation of Kv7 channels prevents, whereas inhibition mimics, the increase in synaptic proteins evoked by the knockdown of NP1. These results indicate that NP1 negatively regulates excitatory synapse number by modulating neuronal excitability and show that NP1 restricts excitatory synaptic plasticity. Copyright © 2015 the authors 0270-6474/15/355504-18$15.00/0.

  16. Shank1 regulates excitatory synaptic transmission in mouse hippocampal parvalbumin-expressing inhibitory interneurons.

    Science.gov (United States)

    Mao, Wenjie; Watanabe, Takuya; Cho, Sukhee; Frost, Jeffrey L; Truong, Tina; Zhao, Xiaohu; Futai, Kensuke

    2015-04-01

    The Shank genes (SHANK1, 2, 3) encode scaffold proteins highly enriched in postsynaptic densities where they regulate synaptic structure in spiny neurons. Mutations in human Shank genes are linked to autism spectrum disorder and schizophrenia. Shank1 mutant mice exhibit intriguing cognitive phenotypes reminiscent of individuals with autism spectrum disorder. However, the molecular mechanisms leading to the human pathophysiological phenotypes and mouse behaviors have not been elucidated. In this study it is shown that Shank1 protein is highly localized in parvalbumin-expressing (PV+) fast-spiking inhibitory interneurons in the hippocampus. Importantly, a lack of Shank1 in hippocampal CA1 PV+ neurons reduced excitatory synaptic inputs and inhibitory synaptic outputs to pyramidal neurons. Furthermore, it is demonstrated that hippocampal CA1 pyramidal neurons in Shank1 mutant mice exhibit a shift in the excitatory and inhibitory balance (E-I balance), a pathophysiological hallmark of autism spectrum disorder. The mutant mice also exhibit lower expression of gephyrin (a scaffold component of inhibitory synapses), supporting the dysregulation of E-I balance in the hippocampus. These results suggest that Shank1 scaffold in PV+ interneurons regulates excitatory synaptic strength and participates in the maintenance of E-I balance in excitatory neurons.

  17. Loss of MeCP2 From Forebrain Excitatory Neurons Leads to Cortical Hyperexcitation and Seizures

    Science.gov (United States)

    Zhang, Wen; Peterson, Matthew; Beyer, Barbara; Frankel, Wayne N.

    2014-01-01

    Mutations of MECP2 cause Rett syndrome (RTT), a neurodevelopmental disorder leading to loss of motor and cognitive functions, impaired social interactions, and seizure at young ages. Defects of neuronal circuit development and function are thought to be responsible for the symptoms of RTT. The majority of RTT patients show recurrent seizures, indicating that neuronal hyperexcitation is a common feature of RTT. However, mechanisms underlying hyperexcitation in RTT are poorly understood. Here we show that deletion of Mecp2 from cortical excitatory neurons but not forebrain inhibitory neurons in the mouse leads to spontaneous seizures. Selective deletion of Mecp2 from excitatory but not inhibitory neurons in the forebrain reduces GABAergic transmission in layer 5 pyramidal neurons in the prefrontal and somatosensory cortices. Loss of MeCP2 from cortical excitatory neurons reduces the number of GABAergic synapses in the cortex, and enhances the excitability of layer 5 pyramidal neurons. Using single-cell deletion of Mecp2 in layer 2/3 pyramidal neurons, we show that GABAergic transmission is reduced in neurons without MeCP2, but is normal in neighboring neurons with MeCP2. Together, these results suggest that MeCP2 in cortical excitatory neurons plays a critical role in the regulation of GABAergic transmission and cortical excitability. PMID:24523563

  18. How to Find Gravitationally Lensed Type Ia Supernovae

    Science.gov (United States)

    Goldstein, Daniel A.; Nugent, Peter E.

    2017-01-01

    Type Ia supernovae (SNe Ia) that are multiply imaged by gravitational lensing can extend the SN Ia Hubble diagram to very high redshifts (z ≳ 2), probe potential SN Ia evolution, and deliver high-precision constraints on H0, w, and Ωm via time delays. However, only one, iPTF16geu, has been found to date, and many more are needed to achieve these goals. To increase the multiply imaged SN Ia discovery rate, we present a simple algorithm for identifying gravitationally lensed SN Ia candidates in cadenced, wide-field optical imaging surveys. The technique is to look for supernovae that appear to be hosted by elliptical galaxies, but that have absolute magnitudes implied by the apparent hosts’ photometric redshifts that are far brighter than the absolute magnitudes of normal SNe Ia (the brightest type of supernovae found in elliptical galaxies). Importantly, this purely photometric method does not require the ability to resolve the lensed images for discovery. Active galactic nuclei, the primary sources of contamination that affect the method, can be controlled using catalog cross-matches and color cuts. Highly magnified core-collapse SNe will also be discovered as a byproduct of the method. Using a Monte Carlo simulation, we forecast that the Large Synoptic Survey Telescope can discover up to 500 multiply imaged SNe Ia using this technique in a 10 year z-band search, more than an order of magnitude improvement over previous estimates. We also predict that the Zwicky Transient Facility should find up to 10 multiply imaged SNe Ia using this technique in a 3 year R-band search—despite the fact that this survey will not resolve a single system.

  19. Type Ia supernovae: Progenitors and evolution with redshift

    Science.gov (United States)

    Nomoto, Ken'ichi; Umeda, Hideyuki; Kobayashi, Chiaki; Hachisu, Izumi; Kato, Mariko; Tsujimoto, Takuji

    2000-06-01

    Relatively uniform light curves and spectral evolution of Type Ia supernovae(SNe Ia) have led to the use of SNe Ia as a ``standard candle'' to determine cosmological parameters. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effects of cosmic and galactic evolutions. Here we first review the single degenerate scenario for the Chandrasekhar mass white dwarf (WD) models of SNe Ia. We identify the progenitor's evolution and population with two channels: (1) the WD+RG (red-giant) and (2) the WD+MS (near main-sequence He-rich star) channels. In these channels, the strong wind from accreting WDs plays a key role, which yields important age and metallicity effects on the evolution. We then address the questions whether the nature of SNe Ia depends systematically on environmental properties such as metallicity and age of the progenitor system and whether significant evolutionary effects exist. We suggest that the variation of the carbon mass fraction X(C) in the C+O WD (or the variation of the initial WD mass) causes the diversity of the brightness of SNe Ia. This model can explain the observed dependences of SNe Ia brightness on the galaxy types and the distance from the galactic center. Finally, applying the metallicity effect on the evolution of SN Ia progenitors, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in different types of galaxies. .

  20. Valproic acid mediates the synaptic excitatory/inhibitory balance through astrocytes--a preliminary study.

    Science.gov (United States)

    Wang, Chao-Chuan; Chen, Po See; Hsu, Chien-Wen; Wu, Shou-Jung; Lin, Chieh-Ting; Gean, Po Wu

    2012-04-27

    Valproic acid (VPA) is one of the most widely used anticonvulsant and mood-stabilizing agents for the treatment of epilepsy and bipolar disorder. However, the underlying therapeutic mechanisms of the treatment of each disease remain unclear. Recently, the anti-epileptic effect of VPA has been found to lead to modulation of the synaptic excitatory/inhibitory balance. In addition, the therapeutic action of VPA has been linked to its effect on astrocytes by regulating gene expression at the molecular level, perhaps through an epigenetic mechanism as a histone deacetylase (HDAC) inhibitor. To provide insight into the mechanisms underlying the actions of VPA, this study investigated whether the synaptic excitatory/inhibitory (E/I) balance could be mediated by VPA through astrocytes. First, using the primary rat neuronal, astroglial, and neuro-glial mixed culture systems, we demonstrated that VPA treatment could regulate the mRNA levels of two post-synaptic cell adhesion molecules(neuroligin-1 and neuregulin-1) and two extracellular matrices (neuronal pentraxin-1and thrombospondin-3) in primary rat astrocyte cultures in a time- and concentration-dependent manner. Moreover, the up-regulation effect of VPA was noted in astrocytes, but not in neurons. In addition, these regulatory effects could be mimicked by sodium butyrate, a HDAC inhibitor, but not by lithium or two other glycogen synthase kinase-3 beta inhibitors. With the known role of these four proteins in regulating the synaptic E/I balance, we further demonstrated that VPA increased excitatory post-synaptic protein (postsynaptic density 95) and inhibitory post-synaptic protein (Gephyrin) in cortical neuro-glial mixed cultures. Our results suggested that VPA might affect the synaptic excitatory/inhibitory balance through its effect on astrocytes. This work provides the basis for future evaluation of the role of astroglial cell adhesion molecules and the extracellular matrix on the control of excitatory and

  1. Cholinergic modulation of excitatory synaptic input integration in hippocampal CA1.

    Science.gov (United States)

    McQuiston, A Rory

    2010-10-01

    During theta rhythm, the timing of inputs to hippocampal CA1 from the perforant path (PP) of the entorhinal cortex and the Schaffer collaterals (SCs) from individual CA3 pyramidal neurons can vary within an individual theta period. Importantly, during theta rhythms these interactions occur during elevated acetylcholine concentrations. Thus, I examined the effect that PP inputs have on SC inputs in hippocampal CA1 during cholinergic receptor activation. To do this I measured the impact that a single electrical stimulus of the stratum lacunosum-moleculare (SLM, which contains the PP) had on excitation evoked by stimulation of the stratum radiatum (SR, which contains the SC) using voltage-sensitive dye imaging, field excitatory postsynaptic potentials and whole cell patch clamping in rat hippocampal brain slices. My data showed that SLM stimulation one half a theta cycle or less (25-75 ms) before SR stimulation resulted in the summation of excitatory events in SR and SP of hippocampal CA1. The summation was unaffected by cholinergic receptor activation by carbachol. SLM stimulation one theta cycle (150-225 ms) preceding SR stimulation significantly suppressed excitatory events measured in SR and SP. This SLM stimulus inhibition of SR-driven excitatory events was augmented by carbachol application. The carbachol effect was blocked by atropine and SLM-driven suppression of excitatory events was blocked by the GABA(B) receptor antagonist CGP 54626. SR field EPSP slopes were unaffected by SLM prepulses. Carbachol increased the probability of SR input to drive action potential firing in CA1 pyramidal neurons, which was inhibited by SLM prepulses (150-225 ms). Together these data provide important information regarding the integration of inputs in hippocampal CA1 during theta rhythms. More specifically, SR inputs can be differentially gated by SLM feedforward inhibition at varying temporal intervals within a theta cycle.

  2. Do personality traits predict individual differences in excitatory and inhibitory learning?

    Directory of Open Access Journals (Sweden)

    Zhimin eHe

    2013-05-01

    Full Text Available Conditioned inhibition (CI is demonstrated in classical conditioning when a stimulus is used to signal the omission of an otherwise expected outcome. This basic learning ability is involved in a wide range of normal behaviour - and thus its disruption could produce a correspondingly wide range of behavioural deficits. The present study employed a computer-based task to measure conditioned excitation and inhibition in the same discrimination procedure. Conditioned inhibition by summation test was clearly demonstrated. Additionally summary measures of excitatory and inhibitory learning (difference scores were calculated in order to explore how performance related to individual differences in a large sample of normal participants (n=176 following exclusion of those not meeting the basic learning criterion. The individual difference measures selected derive from two biologically-based personality theories, Gray’s reinforcement sensitivity theory (1982 and Eysenck’s psychoticism, extraversion and neuroticism theory (1991. Following the behavioural tasks, participants completed the behavioural inhibition system/behavioural activation system scales (BIS/BAS and the Eysenck personality questionnaire revised short scale (EPQ-RS. Analyses of the relationship between scores on each of the scales and summary measures of excitatory and inhibitory learning suggested that those with higher BAS (specifically the drive sub-scale and higher EPQ-RS neuroticism showed reduced levels of excitatory conditioning. Inhibitory conditioning was similarly attenuated in those with higher EPQ-RS neuroticism, as well as in those with higher BIS scores. Thus the findings are consistent with higher levels of neuroticism being accompanied by generally impaired associative learning, both inhibitory and excitatory. There was also evidence for some dissociation in the effects of behavioural activation and behavioural inhibition on excitatory and inhibitory learning respectively.

  3. Do personality traits predict individual differences in excitatory and inhibitory learning?

    Science.gov (United States)

    He, Zhimin; Cassaday, Helen J; Bonardi, Charlotte; Bibby, Peter A

    2013-01-01

    Conditioned inhibition (CI) is demonstrated in classical conditioning when a stimulus is used to signal the omission of an otherwise expected outcome. This basic learning ability is involved in a wide range of normal behavior - and thus its disruption could produce a correspondingly wide range of behavioral deficits. The present study employed a computer-based task to measure conditioned excitation and inhibition in the same discrimination procedure. CI by summation test was clearly demonstrated. Additionally summary measures of excitatory and inhibitory learning (difference scores) were calculated in order to explore how performance related to individual differences in a large sample of normal participants (n = 176 following exclusion of those not meeting the basic learning criterion). The individual difference measures selected derive from two biologically based personality theories, Gray's (1982) reinforcement sensitivity theory and Eysenck and Eysenck (1991) psychoticism, extraversion, and neuroticism theory. Following the behavioral tasks, participants completed the behavioral inhibition system/behavioral activation system (BIS/BAS) scales and the Eysenck personality questionnaire revised short scale (EPQ-RS). Analyses of the relationship between scores on each of the scales and summary measures of excitatory and inhibitory learning suggested that those with higher BAS (specifically the drive sub-scale) and higher EPQ-RS neuroticism showed reduced levels of excitatory conditioning. Inhibitory conditioning was similarly attenuated in those with higher EPQ-RS neuroticism, as well as in those with higher BIS scores. Thus the findings are consistent with higher levels of neuroticism being accompanied by generally impaired associative learning, both inhibitory and excitatory. There was also evidence for some dissociation in the effects of behavioral activation and behavioral inhibition on excitatory and inhibitory learning respectively.

  4. Type Ia and II supernovae contributions to the metal enrichment in intra-cluster medium observed with Suzaku

    CERN Document Server

    Sato, Kosuke; Matsushita, Kyoko; Ishisaki, Yoshitaka; Yamasaki, Noriko Y; Ishida, Manabu; Ohashi, Takaya

    2007-01-01

    We studied the properties of the intra-cluster medium (ICM) in two clusters of galaxies (AWM 7 and Abell 1060) and two groups (HCG 62 and NGC 507) with the X-ray Observatory Suzaku. Based on spatially resolved energy spectra, we measured for the first time precise cumulative ICM metal masses within 0.1 and ~0.3 r_{180}. Comparing our results with supernova nucleosynthesis models, the number ratio of type II (SNe II) to type Ia (SNe Ia) is estimated to be ~3.5, assuming the metal mass in the ICM is represented by the sum of products synthesized in SNe Ia and SNe II. Normalized by the K-band luminosities of present galaxies, and including the metals in stars, the integrated number of past SNe II explosions is estimated to be close to or somewhat higher than the star formation rate determined from Hubble Deep Field observations.

  5. Constraining cosmic isotropy with type Ia supernovae

    CERN Document Server

    Bengaly,, C A P; Alcaniz, J S

    2016-01-01

    We investigate the validity of the Cosmological Principle by constraining the cosmological parameters $H_0$ and $q_0$ through the celestial sphere. Our analyses are performed in a low-redshift regime in order to follow a model independent approach, using both Union2.1 and JLA Type Ia Supernovae (SNe) compilations. We find that the preferred direction of the $H_0$ parameter in the sky is consistent with the bulk flow motion of our local Universe in the Union2.1 case, while the $q_0$ directional analysis seem to be anti-correlated with the $H_0$ for both data sets. Furthermore, we test the consistency of these results with Monte Carlo (MC) realisations, finding that the anisotropy on both parameters are significant within $2-3\\sigma$ confidence level, albeit we find a significant correlation between the $H_0$ and $q_0$ mapping with the angular distribution of SNe from the JLA compilation. Therefore, we conclude that the detected anisotropies are either of local origin, or induced by the non-uniform celestial co...

  6. Turbulent Oxygen Flames in Type Ia Supernovae

    CERN Document Server

    Aspden, A J; Woosley, S E; 10.1088/0004-637X/730/2/144

    2011-01-01

    In previous studies, we examined turbulence-flame interactions in carbon-burning thermonuclear flames in Type Ia supernovae. In this study, we consider turbulence-flame interactions in the trailing oxygen flames. The two aims of the paper are to examine the response of the inductive oxygen flame to intense levels of turbulence, and to explore the possibility of transition to detonation in the oxygen flame. Scaling arguments analogous to the carbon flames are presented and then compared against three-dimensional simulations for a range of Damk\\"ohler numbers ($\\Da_{16}$) at a fixed Karlovitz number. The simulations suggest that turbulence does not significantly affect the oxygen flame when $\\Da_{16}1$, turbulence enhances heat transfer and drives the propagation of a flame that is {\\em narrower} than the corresponding inductive flame would be. Furthermore, burning under these conditions appears to occur as part of a combined carbon-oxygen turbulent flame with complex compound structure. The simulations do not ...

  7. Early emission from type Ia supernovae

    CERN Document Server

    Rabinak, Itay; Waxman, Eli

    2011-01-01

    A unique feature of deflagration-to-detonation (DDT) white dwarf explosion models of SNe of type Ia is the presence of a strong shock wave propagating through the outer envelope. We consider the early emission expected in such models, which is produced by the expanding shock-heated outer part of the ejecta and precedes the emission driven by radioactive decay. We expand on earlier analyses by considering the modification of the pre-detonation density profile by the weak-shocks generated during the deflagration phase, the time evolution of the opacity, and the deviation of the post-shock equation of state from that obtained for radiation pressure domination. A simple analytic model is presented and shown to provide an acceptable approximation to the results of 1D numerical DDT simulations. Our analysis predicts a thousand second long UV/optical flash with a luminosity of ~1 to 3*1e39 erg/s. Lower luminosity corresponds to faster (turbulent) deflagration velocity. The predicted luminosity of the UV flash is an ...

  8. EARLY EMISSION FROM TYPE Ia SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Rabinak, Itay; Waxman, Eli [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Livne, Eli, E-mail: itay.rabinak@weizmann.ac.il [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)

    2012-09-20

    A unique feature of deflagration-to-detonation (DDT) white dwarf explosion models of supernovae of type Ia is the presence of a strong shock wave propagating through the outer envelope. We consider the early emission expected in such models, which is produced by the expanding shock-heated outer part of the ejecta and precedes the emission driven by radioactive decay. We expand on earlier analyses by considering the modification of the pre-detonation density profile by the weak shocks generated during the deflagration phase, the time evolution of the opacity, and the deviation of the post-shock equation of state from that obtained for radiation pressure domination. A simple analytic model is presented and shown to provide an acceptable approximation to the results of one-dimensional numerical DDT simulations. Our analysis predicts a {approx}10{sup 3} s long UV/optical flash with a luminosity of {approx}1 to {approx}3 Multiplication-Sign 10{sup 39} erg s{sup -1}. Lower luminosity corresponds to faster (turbulent) deflagration velocity. The luminosity of the UV flash is predicted to be strongly suppressed at t > t{sub drop} {approx} 1 hr due to the deviation from pure radiation domination.

  9. Star Clusters as Type Ia Supernova Factories

    CERN Document Server

    Shara, M M; Shara, Michael M.; Hurley, Jarrod R.

    2002-01-01

    We find a remarkably enhanced production rate in star clusters (relative to the field) of very short period, massive double-white-dwarf stars and of giant-white dwarf binaries. These results are based on N-body simulations performed with the new GRAPE-6 special purpose hardware and are important in identifying and characterizing the progenitors of type Ia supernovae. The high incidence of very close double-white-dwarf systems is the result of dynamical encounters between (mostly) primordial binaries and other cluster stars. Orbital hardening rapidly drives these degenerate binaries to periods under ~10 hours. Gravitational radiation emission and mergers producing supra-Chandrasekhar objects follow in less than a Hubble time. If most stars are born in clusters then estimates of the double white dwarf merger rates in galaxies (due to cluster dynamical interaction) must be increased more than tenfold. A majority of the Roche lobe overflow giant-white dwarf binaries are not primordial; they are produced in exchan...

  10. Clustering of supernova Ia host galaxies

    CERN Document Server

    Carlberg, R G; Le Borgne, D; Conley, A; Howell, D A; Perrett, K; Astier, Pierre; Balam, D; Balland, C; Basa, S; Hardin, D; Fouchez, D; Guy, J; Hook, I; Pain, R; Pritchet, C J; Regnault, N; Rich, J; Perlmutter, S

    2008-01-01

    For the first time the cross-correlation between type Ia supernova host galaxies and surrounding field galaxies is measured using the Supernova Legacy Survey sample. Over the z=0.2 to 0.9 redshift range we find that supernova hosts are correlated an average of 60% more strongly than similarly selected field galaxies over the 3-100 arcsec range and about a factor of 3 more strongly below 10 arcsec. The correlation errors are empirically established with a jackknife analysis of the four SNLS fields. The hosts are more correlated than the field at a significance of 99% in the fitted amplitude and slope, with the point-by-point difference of the two correlation functions having a reduced $\\chi^2$ for 8 degrees of freedom of 4.3, which has a probability of random occurrence of less than 3x10^{-5}. The correlation angle is 1.5+/-0.5 arcsec, which deprojects to a fixed co-moving correlation length of approximately 6.5+/- 2/h mpc. Weighting the field galaxies with the mass and star formation rate supernova frequencie...

  11. High-velocity Hα Absorption Events in B8 Ia - A2 Ia Supergiant Stars

    Science.gov (United States)

    Morrison, Nancy D.; Markova, N.; Rother, S. J.

    2009-12-01

    Late B- and early A-type supergiants are notorious for the time variability of their Hα line profiles, but the physical cause of the variations is poorly understood. Usually, the line is filled in by emission, and the blue absorption wing does not extend to the terminal wind speed, which is roughly defined by the blue edges of the ultraviolet resonance lines. On rare occasions, however, the blue wing of Hα goes strongly into absorption over a wide velocity range, from the photospheric velocity almost all the way to the terminal wind speed. This phenomenon was first described by Kaufer et al. (1996, A&A, 314, 599), who denoted it by the term, "High-Velocity Absorption Event." In this report, high-resolution spectra from Ritter Observatory will be combined with published spectra to examine the temporal recurrence behavior and strength distribution of high-velocity absorption events and their incidence as a function of stellar parameters for the available sample of stars. All B8- and A0-type, Ia-class, stars in the sample that have been sufficiently well observed, as well as one A2-type star, show the events. However, there is some evidence that hyperluminous stars (luminosity class Ia+) do not show the events. In one of the most extensively observed stars in the sample (Rigel, B8 Ia), there is no clear periodicity in the recurrence times of the events. In addition to the strong events discovered by Kaufer et al. (1996), there is a broad distribution of more frequent, weaker events. Ritter Observatory receives operating support from the National Science Foundation Program for Research and Education with Small Telescopes (PREST) award AST-0440784.

  12. Searching for light echoes due to CSM in SN Ia spectra

    CERN Document Server

    Marino, Sebastián; Förster, Francisco; Folatelli, Gastón; Hamuy, Mario; Hsiao, Eric

    2015-01-01

    We present an analytical model for light echoes (LEs) coming from circumstellar material (CSM) around Type Ia Supernovae (SNe Ia). Using this model we find two spectral signatures at 4100 {\\AA} and 6200 {\\AA} that are useful to identify LEs during the Lira law phase (between 35 and 80 days after maximum light) coming from nearby CSM at distances of 0.01-0.25 pc. We analyze a sample of 89 SNe Ia divided in two groups according to their B-V decline rate during the Lira law phase, and search for LEs from CSM interaction in the group of SNe with steeper slopes by comparing their spectra with our LE model. We find that a model with LEs + pure extinction from interstellar material (ISM) fits better the observed spectra than a pure ISM extinction model that is constant in time, but we find that a decreasing extinction alone explains better the observations without the need of LEs, possibly implying dust sublimation due to the radiation from the SN.

  13. Observational clues to the progenitors of Type-Ia supernovae

    CERN Document Server

    Maoz, Dan; Nelemans, Gijs

    2013-01-01

    Type-Ia supernovae (SNe Ia) are important distance indicators, element factories, cosmic-ray accelerators, kinetic-energy sources in galaxy evolution, and endpoints of stellar binary evolution. It has long been clear that a SN Ia must be the runaway thermonuclear explosion of a degenerate carbon-oxygen stellar core, most likely a white dwarf (WD). However, the specific progenitor systems of SNe Ia, and the processes that lead to their ignition, have not been identified. Two broad classes of progenitor binary systems have long been considered: single-degenerate (SD), in which a WD gains mass from a non-degenerate star; and double-degenerate (DD), involving the merger of two WDs. New theoretical work has enriched these possibilities with some interesting updates and variants. We review the significant recent observational progress in addressing the progenitor problem. We consider clues that have emerged from the observed properties of the various proposed progenitor populations, from studies of their sites, pre...

  14. CIRCUMSTELLAR ABSORPTION IN DOUBLE DETONATION TYPE Ia SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Ken J. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Guillochon, James [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Foley, Ryan J., E-mail: kenshen@astro.berkeley.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-06-20

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.

  15. Type Ia supernova explosion mechanism and implications for cosmology

    Science.gov (United States)

    Maeda, K.

    Type Ia Supernovae (SNe Ia) are believed to be thermonuclear explosions of a white dwarf, and are one of the most mature cosmological standardized candles. However, the explosion mechanism has not yet been fully clarified. Furthermore, they show observational diversities which may be a consequence of either the diversity in the explosion physics and/or surrounding environments, an issue yet to be clarified. In this paper, it is argued that an asymmetry in the explosion is likely a generic feature, and that the diversity arising from various viewing angles can be an origin of observational diversities of SNe Ia seen in their spectral features (suspected possible biases in cosmology) and colors (related to the extinction estimate in cosmology). These findings indicate that at least a part of observational diversities are intrinsic, rather than caused by environment effects, and open up a possibility of using SNe Ia as more precise distance indicators than currently employed.

  16. Muudetud IFRS 3 ja IAS 27 / Monika Peetson

    Index Scriptorium Estoniae

    Peetson, Monika, 1976-

    2008-01-01

    Rahvusvahelise Raamatupidamisstandardite Nõukogu poolt välja antud muudetud standarditest IFRS 3 "Äriühendused" ja IAS 27 "Konsolideeritud ja konsolideerimata finantsaruanded" ning nendega kaasnevatest muudatustest

  17. Muudetud IFRS 3 ja IAS 27 / Monika Peetson

    Index Scriptorium Estoniae

    Peetson, Monika, 1976-

    2008-01-01

    Rahvusvahelise Raamatupidamisstandardite Nõukogu poolt välja antud muudetud standarditest IFRS 3 "Äriühendused" ja IAS 27 "Konsolideeritud ja konsolideerimata finantsaruanded" ning nendega kaasnevatest muudatustest

  18. The Connection between IAS/IFRS and Social Responsibility

    National Research Council Canada - National Science Library

    Stefano Amelio

    2016-01-01

      The aim of the paper is to evaluate the degree of social responsibility arising from the statement of comprehensive income prepared according to IAS/IFRS, to demonstrate whether the values obtained...

  19. Circumstellar Shells in Absorption in Type Ia Supernovae

    CERN Document Server

    Borkowski, K J; Reynolds, S P

    2009-01-01

    Progenitors of Type Ia supernovae (SNe) have been predicted to modify their ambient circumstellar (CSM) and interstellar environments through the action of their powerful winds. While there is X-ray and optical evidence for circumstellar interaction in several remnants of Type Ia SNe, widespread evidence for such interaction in Type Ia SNe themselves has been lacking. We consider prospects for detection of CSM shells that have been predicted to be common around Type Ia SNe. Such shells are most easily detected in Na I absorption lines. Variable (declining) absorption is expected to occur soon after the explosion, primarily during the SN rise time, for shells located within 1 - 10 pc of a SN. The distance of the shell from the SN can be determined by measuring the time scale for line variability.

  20. Functional state of rat liver RNA polymerase IA and IB.

    Science.gov (United States)

    Zoncheddu, A; Accomando, R; Pertica, M; Orunesu, M

    1979-01-01

    Phosphocellulose chromatography has been employed to characterize RNA polymerase I present in two different functional states in rat liver cells. The actively transcribing enzyme solubilized from nuclei appears to belong both to the IA and IB classes, whereas the non-transcribing enzyme present in the cytoplasmic fraction has been found to belong only to the IA class. Indirect and direct evidence indicates, however, that in isolated nuclei only the IB form is to be regarded as the physiological form of the enzyme, the IA form arising as a procedural artefact during the extraction process. It may, therefore, be concluded that rat liver IA and IB RNA polymerase are to be strictly regarded as the non-transcribing and transcribing form of the enzyme, respectively.

  1. Screening for CDG type Ia in Joubert syndrome.

    NARCIS (Netherlands)

    Morava, E.; Cser, B.; Karteszi, J.; Huijben, K.M.; Szonyi, L.; Kosztolanyi, G.Y.; Wevers, R.A.

    2004-01-01

    BACKGROUND: The features of Joubert syndrome include hypotonia, ataxia, characteristic neuro-imaging findings, episodic hypoventilation, psychomotor retardation, and abnormal eye movements. Common symptoms in congenital disorders of glycosylation (CDG) type Ia are muscle hypotonia, cerebellar hypopl

  2. The luminosity calibration of SNe Ia: present status.

    Science.gov (United States)

    Tammann, G. A.; Reindl, B.

    Blue supernovae of type Ia (SNe Ia) have become the most important objects in cosmology being of exceptionally uniform luminosity. Used as relative distance indicators they map deviations from pure Hubble flow and determine the cosmological constant Λ. Once their absolute magnitude is determined they provide the best estimate of the large-scale value of the Hubble constant H0. An HST project is reviewed where Cepheid distances are used for the luminosity calibration of SNe Ia. The mean luminosity of 8 SNe Ia is MB(max) = -19.47±0.07, MV(max) = -19.48±0.07, corresponding - after small corrections for second parameters - to H0(cosmic) = 59±5.

  3. TYPE Ia SUPERNOVAE STRONGLY INTERACTING WITH THEIR CIRCUMSTELLAR MEDIUM

    Energy Technology Data Exchange (ETDEWEB)

    Silverman, Jeffrey M. [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States); Nugent, Peter E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gal-Yam, Avishay; Arcavi, Iair; Ben-Ami, Sagi [Benoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Howell, D. Andrew; Graham, Melissa L. [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Filippenko, Alexei V.; Bloom, Joshua S.; Cenko, S. Bradley; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cao, Yi; Horesh, Assaf; Kulkarni, Shrinivas R. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Chornock, Ryan; Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Coil, Alison L. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Griffith, Christopher V. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Kasliwal, Mansi M., E-mail: jsilverman@astro.as.utexas.edu [Observatories of the Carnegie Institution of Science, Pasadena, CA 91101 (United States); and others

    2013-07-01

    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well studied previously, three were previously known but are analyzed in depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by H{alpha} emission (with widths of {approx}2000 km s{sup -1}) and exhibit large H{alpha}/H{beta} intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They also show possible evidence of dust formation through a decrease in the red wing of H{alpha} 75-100 days past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na I D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be -21.3 mag {<=} M{sub R} {<=} -19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population. This work represents the most detailed analysis of the SN Ia-CSM class to date.

  4. Purification and separation of subsets of human Ia molecules by papain digestion.

    Science.gov (United States)

    Tanigaki, N; Tosi, R; Koyama, K; Pressman, D

    1980-01-01

    Papain digestion of human Ia(-like) molecules was performed under various conditions using 125I-labelled preparation of non-ionic-detergent-solubilized Ia antigens of Daudi cells. The products were examined for their allospecificities by a direct binding reaction with human Ia alloantisera. The Daudi Ia preparation is known to contain Ia molecules of DRw6 specificity, an HLA-DR specificity and also Ia molecules of DC1 specificity, a putative non-HLA-DR specificity. Limited papain digestion cleaved off the hydrophobic portion of human Ia molecules and gave smaller sized Ia products. The cleavage did not affect the Ia alloantigenic determinants and occurred much more readily with molecules of DC1 specificity than with molecules of DRw6 specificity. As a consequence, limited papain digestion of the Daudi Ia pool yielded an Ia preparation with DRw6 specificity but lacking DC1 specificity and another Ia preparation which was enriched in DC1 specificity. The limited papain digestion of the Daudi Ia pool followed by gel filtration and LcH affinity chromatography also produced Ia REPARATIONS OF HIGH PURITY. Extensive papain digestion damaged the Ia alloantigenic determinants but the DC1 determinant was much more resistant than the DRw6 determinant. Thus extensive papain digestion yielded an Ia preparation which was relatively rich in DC1 specificity and essentially devoid of DRw6 specificity. PMID:6155328

  5. Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

    CERN Document Server

    Silverman, Jeffrey M; Gal-Yam, Avishay; Sullivan, Mark; Howell, D Andrew; Filippenko, Alexei V; Arcavi, Iair; Ben-Ami, Sagi; Bloom, Joshua S; Cenko, S Bradley; Cao, Yi; Chornock, Ryan; Clubb, Kelsey I; Coil, Alison L; Foley, Ryan J; Graham, Melissa L; Griffith, Christopher V; Horesh, Assaf; Kasliwal, Mansi M; Kulkarni, Shrinivas R; Leonard, Douglas C; Li, Weidong; Matheson, Thomas; Miller, Adam A; Modjaz, Maryam; Ofek, Eran O; Pan, Yen-Chen; Perley, Daniel A; Poznanski, Dovi; Quimby, Robert M; Steele, Thea N; Sternberg, Assaf; Xu, Dong; Yaron, Ofer

    2013-01-01

    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia show evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well-studied previously, three were previously known but are analyzed in-depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by H{\\alpha} emission (with widths of ~2000 km/s) and exhibit large H{\\alpha}/H{\\beta} intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They...

  6. How SN Ia host-galaxy properties affect cosmological parameters

    CERN Document Server

    Campbell, H; Gilmore, G

    2016-01-01

    We present a systematic study of the relationship between Type Ia Supernova (SN Ia) properties, and the characteristics of their host galaxies, using a sample of 581 SNe Ia from the full Sloan Digital Sky Survey II (SDSS-II) SN Survey. We also investigate the effects of this on the cosmological constraints derived from SNe~Ia. Compared to previous studies, our sample is larger by a factor of $>4$, and covers a substantially larger redshift range (up to z~0.5), which is directly applicable to the volume of cosmological interest. We measure a significant correlation (>5\\sigma) between the host-galaxy stellar-mass and the SN~Ia Hubble Residuals (HR). We find a weak correlation (1.4\\sigma) between the host-galaxy metallicity as measured from emission lines in the spectra, and the SN~Ia HR. We also find evidence that the slope of the correlation between host-galaxy mass and HR is -0.11 $\\mathrm{mag}/\\mathrm{log}(\\mathrm{M}_{\\mathrm{host}}/\\mathrm{M}_{\\odot})$ steeper in lower metallicity galaxies. We test the effe...

  7. Type Ia Supernova Progenitors, Environmental Effects and Cosmic Supernova Rates

    CERN Document Server

    Nomoto, K; Hachisu, I; Kato, M; Kobayashi, C; Tsujimoto, T; Nomoto, Ken'ichi; Umeda, Hideyuki; Hachisu, Izumi; Kato, Mariko; Kobayashi, Chiaki; Tsujimoto, Takuji

    1999-01-01

    Relatively uniform light curves and spectral evolution of Type Ia supernovae (SNe Ia) have led to the use of SNe Ia as a ``standard candle'' to determine cosmological parameters, such as the Hubble constant, the density parameter, and the cosmological constant. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effects of cosmic and galactic evolutions. Here we first review the single degenerate scenario for the Chandrasekhar mass white dwarf (WD) models of SNe Ia. We identify the progenitor's evolution and population with two channels: (1) the WD+RG (red-giant) and (2) the WD+MS (near main-sequence He-rich star) channels. In these channels, the strong wind from accreting white dwarfs plays a key role, which yields important age and metallicity effects on the evolution. We then address the questions whether the nature of SNe Ia depends systematically on environmental properties such as metalli...

  8. Breaking the color-reddening degeneracy in type Ia supernovae

    CERN Document Server

    Sasdelli, M; Hillebrandt, W; Ashall, C; Mazzali, P A; Prentice, S

    2016-01-01

    A new method to study the intrinsic color and luminosity of type Ia supernovae (SNe Ia) is presented. A metric space built using principal component analysis (PCA) on spectral series SNe Ia between -12.5 and +17.5 days from B maximum is used as a set of predictors. This metric space is built to be insensitive to reddening. Hence, it does not predict the part of color excess due to dust-extinction. At the same time, the rich variability of SN Ia spectra is a good predictor of a large fraction of the intrinsic color variability. Such metric space is a good predictor of the epoch when the maximum in the B-V color curve is reached. Multivariate Partial Least Square (PLS) regression predicts the intrinsic B band light-curve and the intrinsic B-V color curve up to a month after maximum. This allows to study the relation between the light curves of SNe Ia and their spectra. The total-to-selective extinction ratio RV in the host-galaxy of SNe Ia is found, on average, to be consistent with typical Milky-Way values. Th...

  9. Trophic factor-induced excitatory synaptogenesis involves postsynaptic modulation of nicotinic acetylcholine receptors.

    Science.gov (United States)

    Woodin, Melanie A; Munno, David W; Syed, Naweed I

    2002-01-15

    Neurotrophic factors have well established roles in neuronal development, although their precise involvement in synapse formation and plasticity is yet to be fully determined. Using soma-soma synapses between identified Lymnaea neurons, we have shown recently that trophic factors are required for excitatory but not inhibitory synapse formation. However, neither the precise site (presynaptic versus postsynaptic cell) nor the underlying mechanisms have yet been defined. In the present study, synapse formation between the presynaptic cell visceral dorsal 4 (VD4) and its postsynaptic partner right pedal dorsal 1 (RPeD1) was examined to define the cellular mechanisms mediating trophic factor-induced excitatory synaptogenesis in cell culture. When paired in a soma-soma configuration in the presence of defined media (DM, nonproteinacious), mutually inhibitory synapses were appropriately reconstructed between VD4 and RPeD1. However, when cells were paired in the presence of increasing concentrations of Lymnaea brain-conditioned medium (CM), a biphasic synapse (initial excitatory synaptic component followed by inhibition) developed. The CM-induced excitatory synapse formation required trophic factor-mediated activation of receptor tyrosine kinases in the postsynaptic cell, RPeD1, and a concomitant modulation of existing postsynaptic nicotinic acetylcholine receptors (nAChRs). Specifically, when RPeD1 was isolated in DM, exogenously applied ACh induced a hyperpolarizing response that was sensitive to the AChR antagonist methyllycaconitine (MLA). In contrast, a single RPeD1 isolated in CM exhibited a biphasic response to exogenously applied ACh. The initial depolarizing phase of the biphasic response was sensitive to both mecamylamine and hexamethonium chloride, whereas the hyperpolarizing phase was blocked by MLA. In soma-soma-paired neurons, the VD4-induced synaptic responses in RPeD1 were sensitive to the cholinergic antagonists in a concentration range similar to that

  10. Postactivation depression of the Ia EPSP in motoneurons is reduced in both the G127X SOD1 model of amyotrophic lateral sclerosis and in aged mice.

    Science.gov (United States)

    Hedegaard, A; Lehnhoff, J; Moldovan, M; Grøndahl, L; Petersen, N C; Meehan, C F

    2015-08-01

    Postactivation depression (PActD) of Ia afferent excitatory postsynaptic potentials (EPSPs) in spinal motoneurons results in a long-lasting depression of the stretch reflex. This phenomenon (PActD) is of clinical interest as it has been shown to be reduced in a number of spastic disorders. Using in vivo intracellular recordings of Ia EPSPs in adult mice, we demonstrate that PActD in adult (100-220 days old) C57BL/6J mice is both qualitatively and quantitatively similar to that which has been observed in larger animals with respect to both the magnitude (with ∼20% depression of EPSPs at 0.5 ms after a train of stimuli) and the time course (returning to almost normal amplitudes by 5 ms after the train). This validates the use of mouse models to study PActD. Changes in such excitatory inputs to spinal motoneurons may have important implications for hyperreflexia and/or glutamate-induced excitotoxicity in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). With the use of the G127X SOD1 mutant mouse, an ALS model with a prolonged asymptomatic phase and fulminant symptom onset, we observed that PActD is significantly reduced at both presymptomatic (16% depression) and symptomatic (17.3% depression) time points compared with aged-matched controls (22.4% depression). The PActD reduction was not markedly altered by symptom onset. Comparing these PActD changes at the EPSP with the known effect of the depression on the monosynaptic reflex, we conclude that this is likely to have a much larger effect on the reflex itself (a 20-40% difference). Nevertheless, it should also be accounted that in aged (580 day old) C57BL/6J mice there was also a reduction in PActD although, aging is not usually associated with spasticity.

  11. Interaction of baseline synaptic noise and Ia EPSPs: evidence for appreciable negative correlation under physiological conditions.

    Science.gov (United States)

    Solodkin, M; Jiménez, I; Collins, W F; Mendell, L M; Rudomin, P

    1991-04-01

    1. In the anesthetized cat, simultaneous intracellular recordings from pairs of spinal motoneurons were undertaken to see whether the amplitude of single-fiber excitatory postsynaptic potentials (EPSPs) in both cells fluctuated in a coordinated manner that would indicate correlative mechanisms at either pre- or post-synaptic level. Although these recordings revealed correlated fluctuations in the baseline, the single-fiber Ia/EPSPs recorded with the spike-triggered averaging technique exhibited no correlated fluctuations and, unexpectedly, virtually no increase in baseline variance associated with the EPSP. However, the fact that these experiments were carried out under conditions of high baseline synaptic noise (i.e., with muscle stretch) may have influenced the outcome because of interaction between EPSP and synaptic noise, and this possibility was evaluated explicitly. 2. A given connection was studied under low noise by electrically stimulating a single Ia fiber in the absence of muscle stretch. The same connection was analyzed under conditions of high noise by activating the fiber and all other stretch receptor afferents with muscle stretch and by using spike-triggered averaging to extract the EPSP. The differences in mean EPSP amplitude at a given connection under conditions of low noise and high noise were minimal. 3. Fluctuations in EPSP amplitude were then determined to see whether these were influenced by presence of baseline synaptic noise and whether the interaction was nonlinear. Two methods were used to measure EPSP fluctuations: measurement of the variance associated with the EPSP, and determination by the use of deconvolution methods of the discrete amplitude components associated with the EPSP. 4. An increase in baseline variance was observed during the EPSP evoked under low noise conditions at all six connections studied in this way. This increase disappeared at two of these connections when examined under high noise. This may help to explain the

  12. Selective Maturation of Temporal Dynamics of Intracortical Excitatory Transmission at the Critical Period Onset.

    Science.gov (United States)

    Miao, Qinglong; Yao, Li; Rasch, Malte J; Ye, Qian; Li, Xiang; Zhang, Xiaohui

    2016-08-01

    Although the developmental maturation of cortical inhibitory synapses is known to be a critical factor in gating the onset of critical period (CP) for experience-dependent cortical plasticity, how synaptic transmission dynamics of other cortical synapses are regulated during the transition to CP remains unknown. Here, by systematically examining various intracortical synapses within layer 4 of the mouse visual cortex, we demonstrate that synaptic temporal dynamics of intracortical excitatory synapses on principal cells (PCs) and inhibitory parvalbumin- or somatostatin-expressing cells are selectively regulated before the CP onset, whereas those of intracortical inhibitory synapses and long-range thalamocortical excitatory synapses remain unchanged. This selective maturation of synaptic dynamics results from a ubiquitous reduction of presynaptic release and is dependent on visual experience. These findings provide an additional essential circuit mechanism for regulating CP timing in the developing visual cortex.

  13. Selective Maturation of Temporal Dynamics of Intracortical Excitatory Transmission at the Critical Period Onset

    Directory of Open Access Journals (Sweden)

    Qinglong Miao

    2016-08-01

    Full Text Available Although the developmental maturation of cortical inhibitory synapses is known to be a critical factor in gating the onset of critical period (CP for experience-dependent cortical plasticity, how synaptic transmission dynamics of other cortical synapses are regulated during the transition to CP remains unknown. Here, by systematically examining various intracortical synapses within layer 4 of the mouse visual cortex, we demonstrate that synaptic temporal dynamics of intracortical excitatory synapses on principal cells (PCs and inhibitory parvalbumin- or somatostatin-expressing cells are selectively regulated before the CP onset, whereas those of intracortical inhibitory synapses and long-range thalamocortical excitatory synapses remain unchanged. This selective maturation of synaptic dynamics results from a ubiquitous reduction of presynaptic release and is dependent on visual experience. These findings provide an additional essential circuit mechanism for regulating CP timing in the developing visual cortex.

  14. Selective localization of Shanks to VGLUT1-positive excitatory synapses in the mouse hippocampus

    Directory of Open Access Journals (Sweden)

    Christopher eHeise

    2016-04-01

    Full Text Available AbstractMembers of the Shank family of multidomain proteins (Shank1, Shank2, and Shank3 are core components of the postsynaptic density (PSD of excitatory synapses. At synaptic sites Shanks serve as scaffolding molecules that cluster neurotransmitter receptors as well as cell adhesion molecules attaching them to the actin cytoskeleton. In this study we investigated the synapse specific localization of Shank1-3 and focused on well-defined synaptic contacts within the hippocampal formation. We found that all three family members are present only at VGLUT1-positive synapses, which is particularly visible at mossy fiber contacts. No costaining was found at VGLUT2-positive contacts indicating that the molecular organization of VGLUT2-associated PSDs diverges from classical VGLUT1-positive excitatory contacts in the hippocampus. In light of SHANK mutations in neuropsychiatric disorders, this study indicates which glutamatergic networks within the hippocampus will be primarily affected by shankopathies.

  15. 17beta-Estradiol reduces excitatory postsynaptic potential (EPSP) amplitude in rat basolateral amygdala neurons.

    Science.gov (United States)

    Womble, Mark D; Andrew, James A; Crook, Joseph J

    2002-10-11

    We examined the actions of estrogen on excitatory synaptic transmission in the basolateral amygdala (BLA), a brain region involved in learning, emotions, and the effects of stress. Intracellular recordings of monosynaptic excitatory postsynaptic potentials (EPSPs) were obtained from BLA neurons in a slice preparation. Bath application of 17beta-estradiol (2 micro M) reduced EPSP amplitude by an average of 77%. This reduction was readily reversed by washing with control saline and was not mimicked by the inactive isomer 17 alpha-estradiol. Other passive and active properties of BLA neurons were unaffected by 17beta-estradiol. The observed EPSP reduction is in sharp contrast to the potentiation of EPSPs by estrogen observed in other brain regions.

  16. Electrical stimulation of dog pudendal nerve regulates the excitatory pudendal-to-bladder reflex

    Directory of Open Access Journals (Sweden)

    Yan-he Ju

    2016-01-01

    Full Text Available Pudendal nerve plays an important role in urine storage and voiding. Our hypothesis is that a neuroprosthetic device placed in the pudendal nerve trunk can modulate bladder function after suprasacral spinal cord injury. We had confirmed the inhibitory pudendal-to-bladder reflex by stimulating either the branch or the trunk of the pudendal nerve. This study explored the excitatory pudendal-to-bladder reflex in beagle dogs, with intact or injured spinal cord, by electrical stimulation of the pudendal nerve trunk. The optimal stimulation frequency was approximately 15-25 Hz. This excitatory effect was dependent to some extent on the bladder volume. We conclude that stimulation of the pudendal nerve trunk is a promising method to modulate bladder function.

  17. Electrical stimulation of dog pudendal nerve regulates the excitatory pudendal-to-bladder reflex.

    Science.gov (United States)

    Ju, Yan-He; Liao, Li-Min

    2016-04-01

    Pudendal nerve plays an important role in urine storage and voiding. Our hypothesis is that a neuroprosthetic device placed in the pudendal nerve trunk can modulate bladder function after suprasacral spinal cord injury. We had confirmed the inhibitory pudendal-to-bladder reflex by stimulating either the branch or the trunk of the pudendal nerve. This study explored the excitatory pudendal-to-bladder reflex in beagle dogs, with intact or injured spinal cord, by electrical stimulation of the pudendal nerve trunk. The optimal stimulation frequency was approximately 15-25 Hz. This excitatory effect was dependent to some extent on the bladder volume. We conclude that stimulation of the pudendal nerve trunk is a promising method to modulate bladder function.

  18. SN 2000cx and SN 2013bh: Extremely Rare, Nearly Twin Type Ia Supernovae

    CERN Document Server

    Silverman, Jeffrey M; Kasliwal, Mansi M; Fox, Ori D; Cao, Yi; Johansson, Joel; Perley, Daniel A; Tal, David; Wheeler, J Craig; Amanullah, Rahman; Arcavi, Iair; Bloom, Joshua S; Gal-Yam, Avishay; Goobar, Ariel; Kulkarni, Shrinivas R; Laher, Russ; Lee, William H; Marion, G H; Nugent, Peter E; Shivvers, Isaac

    2013-01-01

    The Type Ia supernova (SN Ia) SN 2000cx was one of the most peculiar transients ever discovered. While its rise to maximum brightness was typical for a SN Ia, its decline was slower, causing standard light curve fitting algorithms to fail; its spectra indicated a high photospheric temperature. Thirteen years later SN 2013bh (aka iPTF13abc), the first near identical twin of SN 2000cx, was discovered. We obtained optical and near-IR photometry and low-resolution optical spectroscopy of this object from discovery until about 1 month past r-band maximum brightness. The spectra of both objects indicate the presence of iron-group elements (Co II, Ni II, Fe II, Fe III, and high-velocity features [HVFs] of Ti II), intermediate-mass elements (Si II, Si III, and S II), in addition to separate normal velocity features (~12000 km/s) and HVFs (~24000 km/s) of Ca II. Persistent absorption from Fe III and Si III, along with the colour evolution, imply relatively high blackbody temperatures for SNe 2013bh and 2000cx (~12000 ...

  19. Excitatory effect of histamine on neuronal activity of rat cerebellar fastigial nucleus in vitro

    Institute of Scientific and Technical Information of China (English)

    TANG Biao; ZHANG Jun; LI HongZhao; ZHU JingNing; WANG JianJun

    2007-01-01

    The cerebellar fastigial nucleus (FN) holds an important role in motor control and body balance. Previous studies have revealed that the nucleus is innervated by direct hypothalamocerebellar histaminergic fibers. However, the functional role of histaminergic projection in cerebellar FN has never been established. In this study, we investigated the effect of histamine on neuronal firing of cerebellar FN by using slice preparations. Sixty-five FN cells were recorded from 47 cerebellar slices, and a vast majority of the cells responded to histamine stimulation with an excitatory response (58/65, 89.2%). Perfusing slices with low-Ca2+/high-Mg2+ medium did not block the histamine-induced excitation (n=10), supporting a direct postsynaptic action of histamine on the cells. Furthermore, the excitatory effect of histamine on FN neurons was not blocked by selective histamine H1 receptor antagonist triprolidine (n=15) or chlorpheniramine (n=10), but was effectively suppressed by ranitidine (n=15), a highly selective histamine H2 receptor antagonist. On the other hand, highly selective histamine H2 receptor agonist dimaprit (n=20) instead of histamine H1 receptor agonist 2-pyridylethylamine (n=16) mimicked the excitatory effect of histamine on FN neurons. The dimaprit-induced FN neuronal excitation was effectively antagonized by selective histamine H2 receptor antagonist ranitidine (n=13) but not influenced by selective histamine H1 receptor antagonist triprolidine (n=15). These results demonstrate that histamine excites cerebellar FN cells via the histamine H2 receptor mechanism and suggest that the hypothalamocerebellar histaminergic fibers may modulate cerebellar FN-mediated sensorimotor integration through their excitatory innervations on FN neurons.

  20. Mechanism of the differentiation of neural responses to excitatory input signals

    Science.gov (United States)

    Zakharov, D. G.; Kuznetsov, A. S.

    2012-08-01

    A dynamical mechanism of the generation of qualitatively different neural responses to typical excitatory stimuli such as an applied current or AMPA and NMDA synaptic currents has been presented. The mechanism is based on a nonlinearity simulating the calcium-dependent potassium current. It has been shown with the FitzHugh-Nagumo equation that, in the presence of such a nonlinearity, only the NMDA synaptic current can strongly increase the frequency of self-sustained oscillations, whereas other stimuli suppress neural activity.

  1. The Relative Contribution of NMDARs to Excitatory Postsynaptic Currents is Controlled by Ca2+-Induced Inactivation

    OpenAIRE

    Fliza eValiullina; Yulia eZakharova; Andreas eDraguhn; Marat eMukhtarov; Nail eBurnashev; Andrei eRozov

    2016-01-01

    NMDA receptors (NMDARs) are important mediators of excitatory synaptic transmission and plasticity. A hallmark of these channels is their high permeability to Ca2+. At the same time, they are themselves inhibited by the elevation of intracellular Ca2+ concentration. It is unclear however, whether the Ca2+ entry associated with single NMDAR mediated synaptic events is sufficient to self-inhibit their activation. Such auto-regulation would have important effects on the dynamics of synaptic exci...

  2. Immature Hippocampal Neuronal Networks do not Develop Tolerance to the Excitatory Actions of Ethanol

    OpenAIRE

    Galindo, Rafael; Valenzuela, C. Fernando

    2006-01-01

    EtOH (ethanol) damages the hippocampus, a brain region that is involved in learning and memory processes. The mechanisms responsible for this effect of EtOH are not fully understood. We recently demonstrated that acute EtOH exposure potently stimulates oscillatory activity driven by the excitatory actions of GABA in the CA3 region of the neonatal rat hippocampus. This activity can be recorded during the growth spurt period as giant depolarizing potentials (GDPs). Here, we characterized the ef...

  3. Inositol hexakisphosphate suppresses excitatory neurotransmission via synaptotagmin-1 C2B domain in the hippocampal neuron

    Science.gov (United States)

    Yang, Shao-Nian; Shi, Yue; Yang, Guang; Li, Yuxin; Yu, Lina; Shin, Ok-Ho; Bacaj, Taulant; Südhof, Thomas C.; Yu, Jia; Berggren, Per-Olof

    2012-01-01

    Inositol hexakisphosphate (InsP6) levels rise and fall with neuronal excitation and silence, respectively, in the hippocampus, suggesting potential signaling functions of this inositol polyphosphate in hippocampal neurons. We now demonstrate that intracellular application of InsP6 caused a concentration-dependent inhibition of autaptic excitatory postsynaptic currents (EPSCs) in cultured hippocampal neurons. The treatment did not alter the size and replenishment rate of the readily releasable pool in autaptic neurons. Intracellular exposure to InsP6 did not affect spontaneous EPSCs or excitatory amino acid-activated currents in neurons lacking autapses. The InsP6-induced inhibition of autaptic EPSCs was effectively abolished by coapplication of an antibody to synaptotagmin-1 C2B domain. Importantly, preabsorption of the antibody with a GST-WT synaptotagmin-1 C2B domain fragment but not with a GST-mutant synaptotagmin-1 C2B domain fragment that poorly reacted with the antibody impaired the activity of the antibody on the InsP6-induced inhibition of autaptic EPSCs. Furthermore, K+ depolarization significantly elevated endogenous levels of InsP6 and occluded the inhibition of autaptic EPSCs by exogenous InsP6. These data reveal that InsP6 suppresses excitatory neurotransmission via inhibition of the presynaptic synaptotagmin-1 C2B domain-mediated fusion via an interaction with the synaptotagmin Ca2+-binding sites rather than via interference with presynaptic Ca2+ levels, synaptic vesicle trafficking, or inactivation of postsynaptic ionotropic glutamate receptors. Therefore, elevated InsP6 in activated neurons serves as a unique negative feedback signal to control hippocampal excitatory neurotransmission. PMID:22778403

  4. Input to the lateral habenula from the basal ganglia is excitatory, aversive, and suppressed by serotonin

    OpenAIRE

    Shabel, Steven J.; Proulx, Christophe D.; Trias, Anthony; Murphy, Ryan T.; Malinow, Roberto

    2012-01-01

    The lateral habenula (LHb) has recently been identified as a key regulator of the reward system by driving inhibition onto dopaminergic neurons. However, the nature and potential modulation of the major input to the LHb originating from the basal ganglia are poorly understood. Although the output of the basal ganglia is thought to be primarily inhibitory, here we show that transmission from the basal ganglia to the LHb is excitatory, glutamatergic and suppressed by serotonin. Behaviorally, ac...

  5. Some relationships between personality, arousal and the strength of the excitatory process

    OpenAIRE

    Gupta, Sunjai

    1981-01-01

    The primary object of the present investigation was to test the inverted 'U' model developed by investigators of 'arousal' in the west and of the 'strength of the excitatory process' in the Soviet Union to explain the relationship between a variety of factors and measures of behavioural, subjective and physiological response. In the present project adult human subjects took part in four experiments. The following factors were investigated in one or more of them: introversion, neuroticism, 'st...

  6. Complexins facilitate neurotransmitter release at excitatory and inhibitory synapses in mammalian central nervous system.

    Science.gov (United States)

    Xue, Mingshan; Stradomska, Alicja; Chen, Hongmei; Brose, Nils; Zhang, Weiqi; Rosenmund, Christian; Reim, Kerstin

    2008-06-03

    Complexins (Cplxs) are key regulators of synaptic exocytosis, but whether they act as facilitators or inhibitors is currently being disputed controversially. We show that genetic deletion of all Cplxs expressed in the mouse brain causes a reduction in Ca(2+)-triggered and spontaneous neurotransmitter release at both excitatory and inhibitory synapses. Our results demonstrate that at mammalian central nervous system synapses, Cplxs facilitate neurotransmitter release and do not simply act as inhibitory clamps of the synaptic vesicle fusion machinery.

  7. Model-free reconstruction of excitatory neuronal connectivity from calcium imaging signals.

    Directory of Open Access Journals (Sweden)

    Olav Stetter

    Full Text Available A systematic assessment of global neural network connectivity through direct electrophysiological assays has remained technically infeasible, even in simpler systems like dissociated neuronal cultures. We introduce an improved algorithmic approach based on Transfer Entropy to reconstruct structural connectivity from network activity monitored through calcium imaging. We focus in this study on the inference of excitatory synaptic links. Based on information theory, our method requires no prior assumptions on the statistics of neuronal firing and neuronal connections. The performance of our algorithm is benchmarked on surrogate time series of calcium fluorescence generated by the simulated dynamics of a network with known ground-truth topology. We find that the functional network topology revealed by Transfer Entropy depends qualitatively on the time-dependent dynamic state of the network (bursting or non-bursting. Thus by conditioning with respect to the global mean activity, we improve the performance of our method. This allows us to focus the analysis to specific dynamical regimes of the network in which the inferred functional connectivity is shaped by monosynaptic excitatory connections, rather than by collective synchrony. Our method can discriminate between actual causal influences between neurons and spurious non-causal correlations due to light scattering artifacts, which inherently affect the quality of fluorescence imaging. Compared to other reconstruction strategies such as cross-correlation or Granger Causality methods, our method based on improved Transfer Entropy is remarkably more accurate. In particular, it provides a good estimation of the excitatory network clustering coefficient, allowing for discrimination between weakly and strongly clustered topologies. Finally, we demonstrate the applicability of our method to analyses of real recordings of in vitro disinhibited cortical cultures where we suggest that excitatory connections

  8. Model-Free Reconstruction of Excitatory Neuronal Connectivity from Calcium Imaging Signals

    Science.gov (United States)

    Stetter, Olav; Battaglia, Demian; Soriano, Jordi; Geisel, Theo

    2012-01-01

    A systematic assessment of global neural network connectivity through direct electrophysiological assays has remained technically infeasible, even in simpler systems like dissociated neuronal cultures. We introduce an improved algorithmic approach based on Transfer Entropy to reconstruct structural connectivity from network activity monitored through calcium imaging. We focus in this study on the inference of excitatory synaptic links. Based on information theory, our method requires no prior assumptions on the statistics of neuronal firing and neuronal connections. The performance of our algorithm is benchmarked on surrogate time series of calcium fluorescence generated by the simulated dynamics of a network with known ground-truth topology. We find that the functional network topology revealed by Transfer Entropy depends qualitatively on the time-dependent dynamic state of the network (bursting or non-bursting). Thus by conditioning with respect to the global mean activity, we improve the performance of our method. This allows us to focus the analysis to specific dynamical regimes of the network in which the inferred functional connectivity is shaped by monosynaptic excitatory connections, rather than by collective synchrony. Our method can discriminate between actual causal influences between neurons and spurious non-causal correlations due to light scattering artifacts, which inherently affect the quality of fluorescence imaging. Compared to other reconstruction strategies such as cross-correlation or Granger Causality methods, our method based on improved Transfer Entropy is remarkably more accurate. In particular, it provides a good estimation of the excitatory network clustering coefficient, allowing for discrimination between weakly and strongly clustered topologies. Finally, we demonstrate the applicability of our method to analyses of real recordings of in vitro disinhibited cortical cultures where we suggest that excitatory connections are characterized

  9. Oscillatory Dynamics and Oscillation Death in Complex Networks Consisting of Both Excitatory and Inhibitory Nodes

    Institute of Scientific and Technical Information of China (English)

    张立升; 廖旭红; 弭元元; 谷伟风; 胡岗

    2012-01-01

    Zn neural networks, both excitatory and inhibitory cells play important roles in determining the functions of systems. Various dynamical networks have been proposed as artificial neural networks to study the properties of biological systems where the influences of excitatory nodes have been extensively investigated while those of inhibitory nodes have been studied much less. In this paper, we consider a model of oscillatory networks of excitable Boolean maps consisting of both excitatory and inhibitory nodes, focusing on the roles of inhibitory nodes. We find that inhibitory nodes in sparse networks (smM1 average connection degree) play decisive roles in weakening oscillations, and oscillation death occurs after continual weakening of oscillation for sufficiently high inhibitory node density. In the sharp contrast, increasing inhibitory nodes in dense networks may result in the increase of oscillation amplitude and sudden oscillation death at much lower inhibitory node density and the nearly highest excitation activities. Mechanism under these peculiar behaviors of dense networks is explained by the competition of the duplex effects of inhibitory nodes.

  10. GABA is the principal fast-acting excitatory transmitter in the neonatal brain.

    Science.gov (United States)

    Leinekugel, X; Khalilov, I; McLean, H; Caillard, O; Gaiarsa, J L; Ben-Ari, Y; Khazipov, R

    1999-01-01

    gamma-aminobutyric acid (GABA) is the principal neurotransmitter of inhibition in the adult mammalian brain. However, at early stages of development, including the embryonic period and first week of postnatal life, GABA plays the role of main neurotransmitter of excitation. The paradoxical excitatory effect of GABA is caused by an inverted chloride gradient and, therefore, a depolarizing direction of GABA type A (GABAA) receptor mediated responses. In addition, another type of GABAergic inhibition mediated by postsynaptic GABA type B (GABAB) receptors is not functional at early stage of life. In the neonatal rat hippocampus, GABA, acting via GABAA receptors, activates voltage-gated sodium and calcium channels and potentiates the activity of N-methyl-D-aspartate (NMDA) receptors by reducing their voltage-dependent Mg2+ block. The temporal window when GABA exerts excitatory actions coincides with a particular pattern of activity of hippocampal neuronal network that is characterized by periodical giant depolarizing potentials (GDPs) reminiscent of interictal-like epileptiform discharges. Recent studies have shown that GDPs result from the synchronous discharge of GABAergic interneurons and principal glutamatergic pyramidal cells, and they are mediated by the synergistic excitatory actions of GABAA and glutamate receptors. GDPs provide synchronous intracellular Ca2+ oscillations and may, therefore, be implicated in hebbian modulation of developing synapses and activity-dependent formation of the hippocampal network.

  11. Distinct Spatiotemporal Response Properties of Excitatory Versus Inhibitory Neurons in the Mouse Auditory Cortex

    Science.gov (United States)

    Maor, Ido; Shalev, Amos; Mizrahi, Adi

    2016-01-01

    In the auditory system, early neural stations such as brain stem are characterized by strict tonotopy, which is used to deconstruct sounds to their basic frequencies. But higher along the auditory hierarchy, as early as primary auditory cortex (A1), tonotopy starts breaking down at local circuits. Here, we studied the response properties of both excitatory and inhibitory neurons in the auditory cortex of anesthetized mice. We used in vivo two photon-targeted cell-attached recordings from identified parvalbumin-positive neurons (PVNs) and their excitatory pyramidal neighbors (PyrNs). We show that PyrNs are locally heterogeneous as characterized by diverse best frequencies, pairwise signal correlations, and response timing. In marked contrast, neighboring PVNs exhibited homogenous response properties in pairwise signal correlations and temporal responses. The distinct physiological microarchitecture of different cell types is maintained qualitatively in response to natural sounds. Excitatory heterogeneity and inhibitory homogeneity within the same circuit suggest different roles for each population in coding natural stimuli. PMID:27600839

  12. Inhibitory effects of propofol on excitatory synaptic transmission in supraoptic nucleus neurons in vitro.

    Science.gov (United States)

    Zhang, Huan-Huan; Zheng, Chao; Wang, Bang-An; Wang, Meng-Ya

    2015-12-25

    The present study was designed to investigate the inhibitory effects of intravenous general anesthetic propofol (0.1-3.0 mmol/L) on excitatory synaptic transmission in supraoptic nucleus (SON) neurons of rats, and to explore the underlying mechanisms by using intracellular recording technique and hypothalamic slice preparation. It was observed that stimulation of the dorsolateral region of SON could elicit the postsynaptic potentials (PSPs) in SON neurons. Of the 8 tested SON neurons, the PSPs of 7 (88%, 7/8) neurons were decreased by propofol in a concentration-dependent manner, in terms of the PSPs' amplitude (P EPSPs) of 7 cells increased in the condition of picrotoxin (30 µmol/L, a GABA(A) receptor antagonist) pretreatment. On this basis, the inhibitory effects of propofol on EPSPs were decreased. These data indicate that the presynaptic and postsynaptic mechanisms may be both involved in the inhibitory effects of propofol on excitatory synaptic transmission in SON neurons. The inhibitory effects of propofol on excitatory synaptic transmission of SON neurons may be related to the activation of GABA(A) receptors, but at a high concentration, propofol may also act directly on glutamate receptors.

  13. Enhanced quantal release of excitatory transmitter in anterior cingulate cortex of adult mice with chronic pain

    Directory of Open Access Journals (Sweden)

    Zhao Ming-Gao

    2009-01-01

    Full Text Available Abstract The anterior cingulate cortex (ACC is a forebrain structure that plays important roles in emotion, learning, memory and persistent pain. Our previous studies have demonstrated that the enhancement of excitatory synaptic transmission was induced by peripheral inflammation and nerve injury in ACC synapses. However, little information is available on their presynaptic mechanisms, since the source of the enhanced synaptic transmission could include the enhanced probability of neurotransmitter release at existing release sites and/or increases in the number of available vesicles. The present study aims to perform quantal analysis of excitatory synapses in the ACC with chronic pain to examine the source of these increases. The quantal analysis revealed that both probability of transmitter release and number of available vesicles were increased in a mouse model of peripheral inflammation, whereas only probability of transmitter release but not number of available vesicles was enhanced in a mouse model of neuropathic pain. In addition, we compared the miniature excitatory postsynaptic potentials (mEPSCs in ACC synapses with those in other pain-related brain areas such as the amygdala and spinal cord. Interestingly, the rate and amplitude of mEPSCs in ACC synapses were significantly lower than those in the amygdala and spinal cord. Our studies provide strong evidences that chronic inflammatory pain increases both probability of transmitter release and number of available vesicles, whereas neuropathic pain increases only probability of transmitter release in the ACC synapses.

  14. Cannabinoid CB1 receptor signaling dichotomously modulates inhibitory and excitatory synaptic transmission in rat inner retina.

    Science.gov (United States)

    Wang, Xiao-Han; Wu, Yi; Yang, Xiao-Fang; Miao, Yanying; Zhang, Chuan-Qiang; Dong, Ling-Dan; Yang, Xiong-Li; Wang, Zhongfeng

    2016-01-01

    In the inner retina, ganglion cells (RGCs) integrate and process excitatory signal from bipolar cells (BCs) and inhibitory signal from amacrine cells (ACs). Using multiple labeling immunohistochemistry, we first revealed the expression of the cannabinoid CB1 receptor (CB1R) at the terminals of ACs and BCs in rat retina. By patch-clamp techniques, we then showed how the activation of this receptor dichotomously regulated miniature inhibitory postsynaptic currents (mIPSCs), mediated by GABAA receptors and glycine receptors, and miniature excitatory postsynaptic currents (mEPSCs), mediated by AMPA receptors, of RGCs in rat retinal slices. WIN55212-2 (WIN), a CB1R agonist, reduced the mIPSC frequency due to an inhibition of L-type Ca(2+) channels no matter whether AMPA receptors were blocked. In contrast, WIN reduced the mEPSC frequency by suppressing T-type Ca(2+) channels only when inhibitory inputs to RGCs were present, which could be in part due to less T-type Ca(2+) channels of cone BCs, presynaptic to RGCs, being in an inactivation state under such condition. This unique feature of CB1R-mediated retrograde regulation provides a novel mechanism for modulating excitatory synaptic transmission in the inner retina. Moreover, depolarization of RGCs suppressed mIPSCs of these cells, an effect that was eliminated by the CB1R antagonist SR141716, suggesting that endocannabinoid is indeed released from RGCs.

  15. AIDA-1 Moves out of the Postsynaptic Density Core under Excitatory Conditions.

    Directory of Open Access Journals (Sweden)

    Ayse Dosemeci

    Full Text Available AIDA-1 is highly enriched in postsynaptic density (PSD fractions and is considered a major component of the PSD complex. In the present study, immunogold electron microscopy was applied to determine localization as well as the activity-induced redistribution of AIDA-1 at the PSD using two antibodies that recognize two different epitopes. In cultured rat hippocampal neurons under basal conditions, immunogold label for AIDA-1 is mostly located within the dense core of the PSD, with a median distance of ~30 nm from the postsynaptic membrane. Under excitatory conditions, such as depolarization with high K+ (90 mM, 2 min or application of NMDA (50 μM, 2 min, AIDA-1 label density at the PSD core is reduced to 40% of controls and the median distance of label from the postsynaptic membrane increases to ~55 nm. The effect of excitatory conditions on the postsynaptic distribution of AIDA-1 is reversed within 30 minutes after returning to control conditions. The reversible removal of AIDA-1 from the PSD core under excitatory conditions is similar to the redistribution of another abundant PSD protein, SynGAP. Both SynGAP-alpha1 and AIDA-1 are known to bind PSD-95. Activity-induced transient translocation of these abundant proteins from the PSD core could promote structural flexibility, vacate sites on PSD-95 for the insertion of other components and thus may create a window for synaptic modification.

  16. Propofol facilitated excitatory postsynaptic currents frequency on nucleus tractus solitarii (NTS) neurons.

    Science.gov (United States)

    Jin, Zhenhua; Choi, Myung-Jin; Park, Cheung-Seog; Park, Young Seek; Jin, Young-Ho

    2012-01-13

    Propofol, an intravenous anesthetic, is broadly used for general anesthesia and diagnostic sedations due to its fast onset and recovery. Propofol depresses respiratory and cardiovascular reflex responses, however, their underlying mechanisms are not well known. Cardiorespiratory information from visceral afferent vagus nerves is integrated in the nucleus tractus solitarii (NTS). Cardiac and respiratory signals transducing vagal afferent neurons release the excitatory neurotransmitter glutamate onto NTS neurons in an activity dependent manner and trigger negative feedback reflex responses. In this experiment, the effects of propofol on glutamatergic synaptic responses at NTS neurons was tested using patch clamp methods. Glutamatergic excitatory postsynaptic currents (EPSC) were recorded at chloride reversal potential (-49mV) without γ-aminobutyric acid type A (GABA(A)) receptor antagonists. Propofol (≥3μM) facilitated frequency of the spontaneous EPSCs in a concentration dependent manner without altering amplitude and decay time. The GABA(A) receptor selective antagonist, gabazine (6μM), attenuated propofol effects on glutamate release. Propofol (10μM) evoked glutamate release was also blocked in the presence of the voltage dependent Na(+) and Ca(2+) channel blockers TTX (0.3μM) and Cd(2+) (0.2mM), respectively. In addition, the Na(+)-K(+)-Cl(-) cotransporter type 1 antagonist bumetanide (10μM) also inhibited propofol evoked increase in sEPSC frequency. These results suggest that propofol evoked glutamate release onto NTS neurons by GABA(A) receptor-mediated depolarization of the presynaptic excitatory terminals.

  17. Pharmacology of Glutamate Transport in the CNS: Substrates and Inhibitors of Excitatory Amino Acid Transporters (EAATs) and the Glutamate/Cystine Exchanger System x c -

    Science.gov (United States)

    Bridges, Richard J.; Patel, Sarjubhai A.

    As the primary excitatory neurotransmitter in the mammalian CNS, l-glutamate participates not only in standard fast synaptic communication, but also contributes to higher order signal processing, as well as neuropathology. Given this variety of functional roles, interest has been growing as to how the extracellular concentrations of l-glutamate surrounding neurons are regulated by cellular transporter proteins. This review focuses on two prominent systems, each of which appears capable of influencing both the signaling and pathological actions of l-glutamate within the CNS: the sodium-dependent excitatory amino acid transporters (EAATs) and the glutamate/cystine exchanger, system x c - (Sx c -). While the family of EAAT subtypes limit access to glutamate receptors by rapidly and efficiently sequestering l-glutamate in neurons and glia, Sxc - provides a route for the export of glutamate from cells into the extracellular environment. The primary intent of this work is to provide an overview of the inhibitors and substrates that have been developed to delineate the pharmacological specificity of these transport systems, as well as be exploited as probes with which to selectively investigate function. Particular attention is paid to the development of small molecule templates that mimic the structural properties of the endogenous substrates, l-glutamate, l-aspartate and l-cystine and how strategic control of functional group position and/or the introduction of lipophilic R-groups can impact multiple aspects of the transport process, including: subtype selectivity, inhibitory potency, and substrate activity.

  18. IA-Automorphisms of Permutational Wreath Products

    Institute of Scientific and Technical Information of China (English)

    John Panagopoulos

    2001-01-01

    Let W be the permutational wreath product of two groups A and B.In this paper, we study the relationship between the semicompleteness of W and the semicompleteness of A and B. In the general case, we give some necessary conditions for the semicompleteness of the group W. In the case of finite groups A and B with A abelian, we give necessary and sufficient conditions under which the group W is semicomplete.

  19. Thematic trip: "Save Roşia MontanÄă"

    Science.gov (United States)

    Eugenia, Marcu

    2015-04-01

    The name Roşia Montană, situated in Transylvania, became well known after a Romanian-Canadian company, Roşia Montană Gold Company (RMGC), obtained the concession license on exploitation for gold and silver minerals in the Roşia Montană area. The project consists of opening the largest surface gold mines in Europe using cyanide, which will include four open pits and a processing plant for gold and silver in The Roşia Valley and a tailings facility with an area of 367 hectares in the Corna Valley. One of the main fears is related to a possible ecological accident like the one in Baia Mare in 2000, when a tailing facility dam break led to cyanide pollution of Tisa and Danube rivers that resulted in the death of 1,200 tons of fish and contamination of water resources for 2 million people. This thematic trip is important for the scientific preparation of students and an opportunity to educate them in the spirit of environmental protection. The training and education of students will require assimilation and understanding, actively and consciously, using the knowledge acquired during the compulsory curriculum and training skills. REASON: The continuous degradation of the environment is a major crisis due to human intervention in nature, and the proposed Roşia Montană mining project will continue this trend. The company proposes to extract gold from mines by using the gold separation technique using cyanide, a process that involves destroying a total area of 16 km² which includes 5 mountains, 7 churches, 11 cemeteries and the ruins of Alburnus Maior Citadel, as well as creating pollution that would last for hundreds of years. The extraction of gold from low-grade ores using cyanide processes was estimated to result in a worldwide emission of 45,300 tons of hydrogen cyanide. Environmental education for a healthy life has children as target group, because they are the trustees and beneficiaries of tomorrow's natural resources and can influence the attitudes of

  20. Surviving mossy cells enlarge and receive more excitatory synaptic input in a mouse model of temporal lobe epilepsy.

    Science.gov (United States)

    Zhang, Wei; Thamattoor, Ajoy K; LeRoy, Christopher; Buckmaster, Paul S

    2015-05-01

    Numerous hypotheses of temporal lobe epileptogenesis have been proposed, and several involve hippocampal mossy cells. Building on previous hypotheses we sought to test the possibility that after epileptogenic injuries surviving mossy cells develop into super-connected seizure-generating hub cells. If so, they might require more cellular machinery and consequently have larger somata, elongate their dendrites to receive more synaptic input, and display higher frequencies of miniature excitatory synaptic currents (mEPSCs). To test these possibilities pilocarpine-treated mice were evaluated using GluR2-immunocytochemistry, whole-cell recording, and biocytin-labeling. Epileptic pilocarpine-treated mice displayed substantial loss of GluR2-positive hilar neurons. Somata of surviving neurons were 1.4-times larger than in controls. Biocytin-labeled mossy cells also were larger in epileptic mice, but dendritic length per cell was not significantly different. The average frequency of mEPSCs of mossy cells recorded in the presence of tetrodotoxin and bicuculline was 3.2-times higher in epileptic pilocarpine-treated mice as compared to controls. Other parameters of mEPSCs were similar in both groups. Average input resistance of mossy cells in epileptic mice was reduced to 63% of controls, which is consistent with larger somata and would tend to make surviving mossy cells less excitable. Other intrinsic physiological characteristics examined were similar in both groups. Increased excitatory synaptic input is consistent with the hypothesis that surviving mossy cells develop into aberrantly super-connected seizure-generating hub cells, and soma hypertrophy is indirectly consistent with the possibility of axon sprouting. However, no obvious evidence of hyperexcitable intrinsic physiology was found. Furthermore, similar hypertrophy and hyper-connectivity has been reported for other neuron types in the dentate gyrus, suggesting mossy cells are not unique in this regard. Thus

  1. SPECTROSCOPIC OBSERVATIONS OF SN 2012fr: A LUMINOUS, NORMAL TYPE Ia SUPERNOVA WITH EARLY HIGH-VELOCITY FEATURES AND A LATE VELOCITY PLATEAU

    Energy Technology Data Exchange (ETDEWEB)

    Childress, M. J.; Scalzo, R. A.; Sim, S. A.; Tucker, B. E.; Yuan, F.; Schmidt, B. P. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Cenko, S. B.; Filippenko, A. V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Silverman, J. M. [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States); Contreras, C.; Hsiao, E. Y.; Phillips, M.; Morrell, N. [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Jha, S. W.; McCully, C. [Department of Physics and Astronomy, Rutgers, State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Anderson, J. P.; De Jaeger, T.; Forster, F. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Benetti, S. [INAF Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Bufano, F., E-mail: mjc@mso.anu.edu.au [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); and others

    2013-06-10

    We present 65 optical spectra of the Type Ia SN 2012fr, 33 of which were obtained before maximum light. At early times, SN 2012fr shows clear evidence of a high-velocity feature (HVF) in the Si II {lambda}6355 line that can be cleanly decoupled from the lower velocity ''photospheric'' component. This Si II {lambda}6355 HVF fades by phase -5; subsequently, the photospheric component exhibits a very narrow velocity width and remains at a nearly constant velocity of {approx}12,000 km s{sup -1} until at least five weeks after maximum brightness. The Ca II infrared triplet exhibits similar evidence for both a photospheric component at v Almost-Equal-To 12,000 km s{sup -1} with narrow line width and long velocity plateau, as well as an HVF beginning at v Almost-Equal-To 31,000 km s{sup -1} two weeks before maximum. SN 2012fr resides on the border between the ''shallow silicon'' and ''core-normal'' subclasses in the Branch et al. classification scheme, and on the border between normal and high-velocity Type Ia supernovae (SNe Ia) in the Wang et al. system. Though it is a clear member of the ''low velocity gradient'' group of SNe Ia and exhibits a very slow light-curve decline, it shows key dissimilarities with the overluminous SN 1991T or SN 1999aa subclasses of SNe Ia. SN 2012fr represents a well-observed SN Ia at the luminous end of the normal SN Ia distribution and a key transitional event between nominal spectroscopic subclasses of SNe Ia.

  2. Neutrino event counts from Type Ia supernova models

    Science.gov (United States)

    Nagaraj, Gautam; Scholberg, Kate

    2016-01-01

    Core collapse supernovae (SNe) are widely known to be among the universe's primary neutrino factories, releasing ˜99% of their energy, or ˜1053 ergs, in the form of the tiny leptons. On the other hand, less than 4% of the energy of Type Ia SNe is released via neutrinos, hence making Ia SNe impossible to detect (through neutrino observations) at typical supernova distances. For this reason, neutrino signatures from these explosions have very rarely been modeled. We ran time-sliced fluences from non-oscillation pure deflagration and delayed detonation (DDT) Ia models by Odrzywolek and Plewa (2011) through SNOwGLoBES, a software that calculates event rates and other observed quantities of supernova neutrinos in various detectors. We determined Ia neutrino event rates in Hyper-K, a proposed water Cherenkov detector, JUNO, a scintillator detector under construction, and DUNE, a proposed argon detector, and identified criteria to distinguish between the two models (pure deflagration and DDT) based on data from a real supernova (statistically represented by a Poisson distribution around the expected result). We found that up to distances of 8.00, 1.54, and 2.37 kpc (subject to change based on oscillation effects and modified detector efficiencies), we can discern the explosion mechanism with ≥90% confidence in Hyper-K, JUNO, and DUNE, respectively, thus learning more about Ia progenitors.

  3. Type Ia Supernovae from Merging White Dwarfs I. Prompt Detonations

    CERN Document Server

    Moll, Rainer; Kasen, Daniel; Woosley, Stan

    2013-01-01

    Merging white dwarfs are a possible progenitor of Type Ia supernovae (SNe Ia). While it is not entirely clear if and when an explosion is triggered in such systems, numerical models suggest that a detonation might be initiated before the stars have coalesced to form a single compact object. Here we study such "peri-merger" detonations by means of numerical simulations, modeling the disruption and nucleosynthesis of the stars until the ejecta reach the coasting phase. Synthetic light curves and spectra are generated for comparison with observations. Three models are considered with primary masses 0.96 Msun, 1.06 Msun, and 1.20 Msun. Of these, the 0.96 Msun dwarf merging with an 0.81 Msun companion, with a Ni56 yield of 0.58 Msun, is the most promising candidate for reproducing common SNe Ia. The more massive mergers produce unusually luminous SNe Ia with peak luminosities approaching those attributed to "super-Chandrasekhar" mass SNe Ia. While the synthetic light curves and spectra of some of the models resemb...

  4. Spectroscopy of Type Ia Supernovae by the Carnegie Supernova Project

    CERN Document Server

    Folatelli, Gastón; Phillips, Mark M; Hsiao, Eric; Campillay, Abdo; Contreras, Carlos; Castellón, Sergio; Hamuy, Mario; Krzeminski, Wojtek; Roth, Miguel; Stritzinger, Maximilian; Burns, Christopher R; Freedman, Wendy L; Madore, Barry F; Murphy, David; Persson, S E; Prieto, José L; Suntzeff, Nicholas B; Krisciunas, Kevin; Anderson, Joseph P; Förster, Francisco; Maza, José; Pignata, Giuliano; Rojas, P Andrea; Boldt, Luis; Salgado, Francisco; Wyatt, Pamela; E., Felipe Olivares; Gal-Yam, Avishay; Sako, Masao

    2013-01-01

    This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts, and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further s...

  5. SN IA in the IR: RAISIN A progress report

    Science.gov (United States)

    Kirshner, Robert P.; The RAISIN TEAM

    2014-01-01

    SN Ia have proven to be a powerful tool for cosmology. Near-IR observations of SN Ia promise even better results because the supernovae are more nearly standard candles at those wavelengths and absorption by dust is diminished by a factor of 4 compared to rest-frame B-band observations. Near IR observations of cosmologically-distant SN Ia discovered with PanSTARRS are underway using the infrared camera on the Hubble Space Telescope (GO-13046). These targets are discovered in the difference images created in the CfA/JHU pipeline, confirmed spectroscopically at the MMT, Magellan, Gemini, or Keck, and inserted in a non-disruptive way into the HST observing schedule for WFC3-IR. We have observed over 20 SN Ia in the range 0.2 color and reddening by dust. Since SN IA behave better in the IR in both these ways, there is reason to expect that this approach will be effective in driving down the systematic errors over time. If we are diligent in building up the size of the sample that is observed in the rest-frame infrared, we can expect more certain knowledge of the properties of dark energy. Unsolved problems include constructing precise K-corrections and firming up the fundamental photometric system in y, J, H, and K, but this approach seems a promising one for the HST era now, JWST soon, and WFIRST in good time.

  6. Type Ia Supernovae, Evolution and the Cosmological Constant

    CERN Document Server

    Drell, P S; Wasserman, I M; Drell, Persis S.; Loredo, Thomas J.; Wasserman, Ira

    2000-01-01

    We explore the possible role of evolution in the analysis of data on SNe Ia at cosmological distances. First, using a variety of simple sleuthing techniques, we find evidence that the properties of the high and low redshift SNe Ia observed so far differ from one another. Next, we examine the effects of including simple phenomenological models for evolution in the analysis. The result is that cosmological models and evolution are highly degenerate with one another, so that the incorporation of even very simple models for evolution makes it virtually impossible to pin down the values of $\\Omega_M$ and cosmological constant, respectively. Moreover, we show that if SNe Ia evolve with time, but evolution is neglected in analyzing data, then, given enough SNe Ia, the analysis hones in on values of $\\Omega_M$ and $\\Omega_\\Lambda$ which are incorrect. Using Bayesian methods, we show that the probability that the cosmological constant is nonzero (rather than zero) is unchanged by the SNe Ia data when one accounts for ...

  7. Cosmological Inference from Host-Selected Type Ia Supernova Samples

    Science.gov (United States)

    Uddin, Syed A.; Mould, Jeremy; Lidman, Chris; Ruhlmann-Kleider, Vanina; Hardin, Delphine

    2017-01-01

    We compare two Type Ia supernova samples that are drawn from a spectroscopically confirmed Type Ia supernova sample: a host-selected sample in which SNe Ia are restricted to those that have a spectroscopic redshift from the host; and a broader, more traditional sample in which the redshift could come from either the SN or the host. The host-selected sample is representative of SN samples that will use the redshift of the host to infer the SN redshift, long after the SN has faded from view. We find that SNe Ia that are selected on the availability of a redshift from the host differ from SNe Ia that are from the broader sample. The former tend to be redder, have narrower light curves, live in more massive hosts, and tend to be at lower redshifts. We find that constraints on the equation of state of dark energy, w, and the matter density, ΩM, remain consistent between these two types of samples. Our results are important for ongoing and future supernova surveys, which unlike previous supernova surveys, will have limited real-time follow-up to spectroscopically classify the SNe they discover. Most of the redshifts in these surveys will come from the hosts.

  8. Using Spectral Flux Ratios to Standardize SN Ia Luminosities

    CERN Document Server

    Bailey, S; Antilogus, P; Aragon, C; Baltay, C; Bongard, S; Buton, C; Childress, M; Chotard, N; Copin, Y; Gangler, E; Loken, S; Nugent, P; Pain, R; Pécontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigaudier, G; Runge, K; Scalzo, R; Smadja, G; Swift, H; Tao, C; Thomas, R C; Wu, C

    2009-01-01

    We present a new method to standardize Type Ia supernova (SN Ia) luminosities to ~<0.13 magnitudes using flux ratios from a single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotomery of 58 SNe Ia, we performed an unbiased search for flux ratios which correlate with SN Ia luminosity. After developing the method and selecting the best ratios from a training sample, we verified the results on a separate validation sample and with data from the literature. We identified multiple flux ratios whose correlations with luminosity are stronger than those of light curve shape and color, previously identified spectral feature ratios, or equivalent width measurements. In particular, the flux ratio R(642/443) = F(642 nm) / F(443 nm) has a correlation of 0.95 with SN Ia absolute magnitudes. Using this single ratio as a correction factor produces a Hubble diagram with a residual scatter standard deviation of 0.125 +- 0.011 mag, compared with 0.161 +- 0.015 mag when fit with the SALT2 light cur...

  9. What sodium absorption lines tell us about type Ia supernovae

    CERN Document Server

    Soker, Noam

    2014-01-01

    We propose that the sodium responsible for the variable Na I D absorption lines in some type Ia supernovae (SN Ia) originate from dust residing at ~1pc from the supernovae. In this Na-from-dust absorption (NaDA) model the process by which the SN Ia peak luminosity releases sodium from dust at ~1pc from the SN is similar to the processes by which solar radiation releases sodium from comet dust when comets approach a distance of ~1AU from the Sun. The dust grains are not sublimated but rather stay intact, and release sodium by photon-stimulated desorption (PSD; or photo-sputtering). We apply the NaDA model to SN 2006X and SN 2007le, and find it to comply better with the observed time variability of the Na I D absorption lines than the Na recombination model. The mass in the dusty shell of the NaDA model is much too high to be accounted for in the single-degenerate scenario for SN Ia. Therefore, the presence of variable Na I D lines in some SN Ia further weakens the already very problematic single-degenerate sce...

  10. Neutronization During Carbon Simmering In Type Ia Supernova Progenitors

    Science.gov (United States)

    Martínez-Rodríguez, Héctor; Piro, Anthony L.; Schwab, Josiah; Badenes, Carles

    2016-07-01

    When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ˜103-104 years of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the MESA stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ≈ 3 × 10-4. This is ≈ 70% lower than that found in previous studies that do not take the full density and temperature profile of the simmering region into account. Our results imply that the progenitor metallicity is the main contributor to the neutron excess in SN Ia fuel for Z ≳ 1/3 Z ⊙. Alternatively, at lower metallicities, this neutron excess provides a floor that should be present in any centrally-ignited SN Ia scenario.

  11. Signatures of A Companion Star in Type Ia Supernovae

    CERN Document Server

    Maeda, Keiichi; Shigeyama, Toshikazu

    2014-01-01

    While type Ia Supernovae (SNe Ia) have been used as precise cosmological distance indicators, their progenitor systems remain unresolved. One of the key questions is if there is a non-degenerate companion star at the time of a thermonuclear explosion of a white dwarf (WD). In this paper, we investigate if an interaction between the SN ejecta and the companion star may result in observable footprints around the maximum brightness and thereafter, by performing multi-dimensional radiation transfer simulations based on hydrodynamic simulations of the interaction. We find that such systems result in variations in various observational characteristics due to different viewing directions, while the predicted behaviors (redder and fainter for the companion direction) are opposite to what were suggested by the previous study. The variations are generally modest and within observed scatters. However, the model predicts trends between some observables different from observationally derived, thus a large sample of SNe Ia...

  12. Type Ia supernovae yielding distances with 3-4% precision

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Patrick L. [Univ. of California, Berkeley, CA (United States); Filippenko, Alexei V. [Univ. of California, Berkeley, CA (United States); Burke, David L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hicken, Malcolm [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Ganeshalingam, Mohan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zheng, Weikang [Univ. of California, Berkeley, CA (United States)

    2015-01-26

    The luminosities of Type Ia supernovae (SN), the thermonuclear explosions of white dwarf stars, vary systematically with their intrinsic color and light-curve decline rate. These relationships have been used to calibrate their luminosities to within ~0.14–0.20 mag from broadband optical light curves, yielding individual distances accurate to ~7–10%. Here we identify a subset of SN Ia that erupt in environments having high ultraviolet surface brightness and star-formation surface density. When we apply a steep model extinction law, these SN can be calibrated to within ~0.065–0.075 mag, corresponding to ~3–4% in distance — the best yet with SN Ia by a substantial margin. The small scatter suggests that variations in only one or two progenitor properties account for their light-curve-width/color/luminosity relation.

  13. Consolidated Financial Statements – in IAS 27 perspective

    Directory of Open Access Journals (Sweden)

    Mihai Deju

    2012-12-01

    Full Text Available The aspects concerning the preparation and publication of the consolidated financial statements have been the subject of the settlement by the Committee for International Accounting Standards (IAS even since 1976 with the publication of IAS 3 “Consolidated financial statements”. Subsequently, the standard has been amended and revised successively, on several occasions. The latest version issued in 2008 includes changes on the accounting of interests that do not control and the loss of control on a subsidiary. The actual version also includes the subsequent amendments resulting from IFRS issued until 31st of December 2010. This paper presents the essential aspects of IAS 27 (the actual version and a practical example of how to elaborate consolidated accounts in accordance with this standard.

  14. K-corrections and extinction corrections for Type Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, Peter; Kim, Alex; Perlmutter, Saul

    2002-05-21

    The measurement of the cosmological parameters from Type Ia supernovae hinges on our ability to compare nearby and distant supernovae accurately. Here we present an advance on a method for performing generalized K-corrections for Type Ia supernovae which allows us to compare these objects from the UV to near-IR over the redshift range 0 < z < 2. We discuss the errors currently associated with this method and how future data can improve upon it significantly. We also examine the effects of reddening on the K-corrections and the light curves of Type Ia supernovae. Finally, we provide a few examples of how these techniques affect our current understanding of a sample of both nearby and distant supernovae.

  15. Supernova Acceleration Probe: Studying Dark Energy with Type Ia Supernovae

    CERN Document Server

    Albert, J; Allam, S; Althouse, W E; Amanullah, R; Annis, J; Astier, Pierre; Aumeunier, M; Bailey, S; Baltay, C; Barrelet, E; Basa, S; Bebek, C; Bergström, L; Bernstein, G; Bester, M; Besuner, B; Bigelow, B; Blandford, R; Bohlin, R; Bonissent, A; Bower, C; Brown, M; Campbell, M; Carithers, W; Cole, D; Commins, Eugene D; Craig, W; Davis, T; Dawson, K; Day, C; De Harveng, M; De Jongh, F; Deustua, S; Diehl, H; Dobson, T; Dodelson, S; Ealet, A; Ellis, R; Emmet, W; Figer, D; Fouchez, D; Frerking, M; Frieman, J A; Fruchter, A; Gerdes, D; Gladney, L; Goldhaber, G; Goobar, A; Groom, D; Heetderks, H; Hoff, M; Holland, S; Huffer, M; Hui, L; Huterer, D; Jain, B; Jelinsky, P; Juramy, C; Karcher, A; Kent, S; Kahn, S; Kim, A; Kolbe, W; Krieger, B; Kushner, G; Kuznetsova, N; Lafever, R; Lamoureux, J; Lampton, M; Lefèvre, O; Lebrun, V; Levi, M; Limon, P; Lin, H; Linder, E; Loken, S; Lorenzon, W; Malina, R; Marian, L; Marriner, J P; Marshall, P; Massey, R; Mazure, A; McGinnis, B; McKay, T; McKee, S; Miquel, R; Mobasher, B; Morgan, N; Mortsell, E; Mostek, N; Mufson, S; Musser, J; Nakajima, R; Nugent, P; Olus, H; Pain, R; Palaio, N; Pankow, D; Peoples, John; Perlmutter, S; Peterson, D; Prieto, E; Rabinowitz, D; Réfrégier, A; Rhodes, J; Roe, N; Rusin, D; Scarpine, V; Schubnell, M; Seiffert, M; Sholl, M; Shukla, H; Smadja, G; Smith, R M; Smoot, George F; Snyder, J; Spadafora, A; Stabenau, F; Stebbins, A; Stoughton, C; Szymkowiak, A; Tarle, G; Taylor, K; Tilquin, A; Tomasch, A; Tucker, D; Vincent, D; Von der Lippe, H; Walder, J P; Wang, G; Weinstein, A; Wester, W; White, M

    2005-01-01

    The Supernova Acceleration Probe (SNAP) will use Type Ia supernovae (SNe Ia) as distance indicators to measure the effect of dark energy on the expansion history of the Universe. (SNAP's weak-lensing program is described in a companion White Paper.) The experiment exploits supernova distance measurements up to their fundamental systematic limit; strict requirements on the monitoring of each supernova's properties lead to the need for a space-based mission. Results from pre-SNAP experiments, which characterize fundamental SN Ia properties, will be used to optimize the SNAP observing strategy to yield data, which minimize both systematic and statistical uncertainties. SNAP has achieved technological readiness and the collaboration is poised to begin construction.

  16. The Supernova Type Ia Rate Evolution with SNLS

    CERN Document Server

    Neill, J D; Balam, D; Pritchet, C J; Howell, D A; Perrett, K; Astier, Pierre; Aubourg, E; Basa, S; Carlberg, R G; Conley, A; Fabbro, S; Fouchez, D; Guy, J; Hook, I; Pain, R; Palanque-Delabrouille, Nathalie; Regnault, N; Rich, J; Taillet, R; Aldering, G; Antilogus, P; Arsenijevic, V; Balland, C; Baumont, S; Bronder, J; Ellis, Richard S; Filiol, M; Hardin, D; Kowalski, M; Lidman, C; Lusset, V; Mouchet, M; Mourao, A; Perlmutter, S; Ripoche, P; Schlegel, D J; Tao, C

    2007-01-01

    We present a progress report on a project to derive the evolution of the volumetric supernova Type Ia rate from the Supernova Legacy Survey. Our preliminary estimate of the rate evolution divides the sample from Neill et al. (2006) into two redshift bins: 0.2 < z < 0.4, and 0.4 < z < 0.6. We extend this by adding a bin from the sample analyzed in Sullivan et al. (2006) in the range 0.6 < z < 0.75 from the same time period. We compare the derived trend with previously published rates and a supernova Type Ia production model having two components: one component associated closely with star formation and an additional component associated with host galaxy mass. Our observed trend is consistent with this model, which predicts a rising SN Ia rate out to at least z=2.

  17. Flame fronts in Supernovae Ia and their pulsational stability

    CERN Document Server

    Glazyrin, S I; Dolgov, A D

    2013-01-01

    The structure of the deflagration burning front in type Ia supernovae is considered. The parameters of the flame are obtained: its normal velocity and thickness. The results are in good agreement with previous work of different authors. After that the question of pulsational instability of the flame subject to plane perturbations is considered. The flame can be unstable if hydrodynamics can be ignored, e.g. in solid-body propellants. However, with account of hydrodynamics we find that the flame in type Ia supernovae is pulsationally stable with realistic parameters of reactions and thermal conduction.

  18. Polarisation Spectral Synthesis For Type Ia Supernova Explosion Models

    Science.gov (United States)

    Bulla, Mattia

    2017-02-01

    Despite their relevance across a broad range of astrophysical research topics, Type Ia supernova explosions are still poorly understood and answers to the questions of when, why and how these events are triggered remain unclear. In this respect, polarisation offers a unique opportunity to discriminate between the variety of possible scenarios. The observational evidence that Type Ia supernovae are associated with rather low polarisation signals (smaller than a few per cent) places strong constraints for models and calls for modest asphericities in the progenitor system and/or explosion mechanism.The goal of this thesis is to assess the validity of contemporary Type Ia supernova explosion models by testing whether their predicted polarisation signatures can account for the small signals usually observed. To this end, we have implemented and tested an innovative Monte Carlo scheme in the radiative transfer code artis. Compared to previous Monte Carlo approaches, this technique produces synthetic observables (light curves, flux and polarisation spectra) with a substantial reduction in the Monte Carlo noise and therefore in the required computing time. This improvement is particularly crucial for our study as we aim to extract very weak polarisation signals, comparable to those detected in Type Ia supernovae. We have also demonstrated the applicability of this method to other classes of supernovae via a preliminary study of the first spectropolarimetry observations of superluminous supernovae.Using this scheme, we have calculated synthetic spectropolarimetry for three multi-dimensional explosion models recently proposed as promising candidates to explain Type Ia supernovae. Our findings highlight the power of spectropolarimetry in testing and discriminating between different scenarios. While all the three models predict light curves and flux spectra that are similar to each others and reproduce those observed in Type Ia supernovae comparably well, polarisation does

  19. IA/DA waves and polar mesospheric summer echoes

    Energy Technology Data Exchange (ETDEWEB)

    D' Angelo, N. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)]. E-mail: nicola-dangelo@uiowa.edu

    2005-03-07

    Excitation of ion-acoustic (IA) and dust-acoustic (DA) waves in the Earth's mesosphere, at altitudes of {approx} 85 km, is considered as a possible cause of polar mesospheric summer echoes (PMSE). Although electric fields of a few tens of mV/m appear to be capable of producing IA waves, these fields are too small for exciting DA waves. Since some of the observed features of PMSE conform to the expected properties of DA waves, alternative mechanisms for DA wave excitation should be considered, such as excitation by velocity shear.

  20. Optical Identification of Cepheids in 19 Host Galaxies of Type Ia Supernovae and NGC 4258 with the Hubble Space Telescope

    Science.gov (United States)

    Hoffmann, Samantha L.; Macri, Lucas M.; Riess, Adam G.; Yuan, Wenlong; Casertano, Stefano; Foley, Ryan J.; Filippenko, Alexei V.; Tucker, Brad E.; Chornock, Ryan; Silverman, Jeffrey M.; Welch, Douglas L.; Goobar, Ariel; Amanullah, Rahman

    2016-10-01

    We present results of an optical search conducted as part of the SH0ES project (Supernovae and H0 for the Equation of State of dark energy) for Cepheid variable stars using the Hubble Space Telescope (HST) in 19 hosts of Type Ia supernovae (SNe Ia) and the maser-host galaxy NGC 4258. The targets include nine newly imaged SN Ia hosts using a novel strategy based on a long-pass filter that minimizes the number of HST orbits required to detect and accurately determine Cepheid properties. We carried out a homogeneous reduction and analysis of all observations, including new universal variability searches in all SN Ia hosts, which yielded a total of 2200 variables with well-defined selection criteria, the largest such sample identified outside the Local Group. These objects are used in a companion paper to determine the local value of H0 with a total uncertainty of 2.4%. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  1. Does excitatory fronto-extracephalic tDCS lead to improved working memory performance? [v1; ref status: indexed, http://f1000r.es/216

    Directory of Open Access Journals (Sweden)

    Níall Lally

    2013-10-01

    Full Text Available Evidence suggests that excitatory transcranial direct current stimulation (tDCS may improve performance on a wide variety of cognitive tasks. Due to the non-invasive and inexpensive nature of the method, harnessing its potential could be particularly useful for the treatment of neuropsychiatric illnesses involving cognitive dysfunction. However, questions remain regarding the efficacious stimulation parameters. Here, using a double-blind between-subjects design, we explored whether 1 mA excitatory (anodal left dorsolateral prefrontal cortex stimulation with a contralateral extracephalic reference electrode, leads to enhanced working memory performance across two days, relative to sham stimulation. Participants performed the 3-back, a test of working memory, at baseline, and during and immediately following stimulation on two days, separated by 24-48 hours. Active stimulation did not significantly enhance performance versus sham over the course of the experiment. However, exploratory comparisons did reveal a significant effect of stimulation group on performance during the first stimulation phase only, with active stimulation recipients performing better than sham. While these results do not support the hypothesis that dorsolateral prefrontal cortex tDCS boosts working memory, they raise the possibility that its effects may be greatest during early learning stages.

  2. Palomar Transient Factory Discovers Another Possible super- Chandrasekhar Type Ia Supernova

    Science.gov (United States)

    Nugent, P. E.; Howell, D. A.; Sullivan, M.; Suzuki, N.; Cucchiara, A.; Botyanszki, J.; Hsiao, E. Y.

    2010-10-01

    The Type Ia supernova science working group of the Palomar Transient Factory (ATEL#1964) reports the discovery of a possible super-Chandrasekhar mass supernova, PTF10xgx. The supernova is at RA = 00:12:23.15, Dec = +02:30:44.1 (J2000) in the galaxy identified as APMUKS(BJ) B000949.39+021401.7 (Maddox et al. 1990, MNRAS, 243, 692). The supernova was discovered and classified by Oarical, an autonomous software framework of the PTF collaboration, based on observations made with the Palomar 48-inch Oschin Schmidt telescope.

  3. Homeostatic regulation of excitatory synapses on striatal medium spiny neurons expressing the D2 dopamine receptor.

    Science.gov (United States)

    Thibault, Dominic; Giguère, Nicolas; Loustalot, Fabien; Bourque, Marie-Josée; Ducrot, Charles; El Mestikawy, Salah; Trudeau, Louis-Éric

    2016-05-01

    Striatal medium spiny neurons (MSNs) are contacted by glutamatergic axon terminals originating from cortex, thalamus and other regions. The striatum is also innervated by dopaminergic (DAergic) terminals, some of which release glutamate as a co-transmitter. Despite evidence for functional DA release at birth in the striatum, the role of DA in the establishment of striatal circuitry is unclear. In light of recent work suggesting activity-dependent homeostatic regulation of glutamatergic terminals on MSNs expressing the D2 DA receptor (D2-MSNs), we used primary co-cultures to test the hypothesis that stimulation of DA and glutamate receptors regulates the homeostasis of glutamatergic synapses on MSNs. Co-culture of D2-MSNs with mesencephalic DA neurons or with cortical neurons produced an increase in spines and functional glutamate synapses expressing VGLUT2 or VGLUT1, respectively. The density of VGLUT2-positive terminals was reduced by the conditional knockout of this gene from DA neurons. In the presence of both mesencephalic and cortical neurons, the density of synapses reached the same total, compatible with the possibility of a homeostatic mechanism capping excitatory synaptic density. Blockade of D2 receptors increased the density of cortical and mesencephalic glutamatergic terminals, without changing MSN spine density or mEPSC frequency. Combined blockade of AMPA and NMDA glutamate receptors increased the density of cortical terminals and decreased that of mesencephalic VGLUT2-positive terminals, with no net change in total excitatory terminal density or in mEPSC frequency. These results suggest that DA and glutamate signaling regulate excitatory inputs to striatal D2-MSNs at both the pre- and postsynaptic level, under the influence of a homeostatic mechanism controlling functional output of the circuit.

  4. Enhancement by citral of glutamatergic spontaneous excitatory transmission in adult rat substantia gelatinosa neurons.

    Science.gov (United States)

    Zhu, Lan; Fujita, Tsugumi; Jiang, Chang-Yu; Kumamoto, Eiichi

    2016-02-10

    Although citral, which is abundantly present in lemongrass, has various actions including antinociception, how citral affects synaptic transmission has not been examined as yet. Citral activates in heterologous cells transient receptor potential vanilloid-1, ankyrin-1, and melastatin-8 (TRPV1, TRPA1, and TRPM8, respectively) channels, the activation of which in the spinal lamina II [substantia gelatinosa (SG)] increases the spontaneous release of L-glutamate from nerve terminals. It remains to be examined what types of transient receptor potential channel in native neurons are activated by citral. With a focus on transient receptor potential activation, we examined the effect of citral on glutamatergic spontaneous excitatory transmission using the whole-cell patch-clamp technique to SG neurons in adult rat spinal cord slices. Bath-applied citral for 3 min increased the frequency of spontaneous excitatory postsynaptic current in a concentration-dependent manner (half-maximal effective concentration=0.58 mM), with a small increase in its amplitude. The spontaneous excitatory postsynaptic current frequency increase produced by citral was repeated at a time interval of 30 min, albeit this action recovered with a slow time course after washout. The presynaptic effect of citral was inhibited by TRPA1 antagonist HC-030031, but not by voltage-gated Na-channel blocker tetrodotoxin, TRPV1 antagonist capsazepine, and TRPM8 antagonist BCTC. It is concluded that citral increases spontaneous L-glutamate release in SG neurons by activating TRPA1 channels. Considering that the SG plays a pivotal role in modulating nociceptive transmission from the periphery, the citral activity could contribute toward at least a part of the modulation.

  5. Excitatory and inhibitory actions of isoflurane on the cholinergic ascending arousal system of the rat.

    Science.gov (United States)

    Dong, Hai-Long; Fukuda, Satoru; Murata, Eri; Higuchi, Takashi

    2006-01-01

    The cholinergic arousal systems are known to critically regulate the state of consciousness. The aim of this study was to determine the effect of isoflurane on the inhibitory or excitatory neurotransmitters efflux in important nuclei within the cholinergic arousal system using in vivo intracerebral microdialysis. The efflux of glutamate, gamma-aminobutyric acid (GABA), or acetylcholine in the posterior hypothalamus (PH), the basal forebrain (BF), and the somatosensory cortex (S1BF) of rats was detected using intracerebral microdialysis under an awake condition and at 0.5-2.0 minimum alveolar concentration (MAC) isoflurane anesthesia. The intrabasalis perfusion of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate on the cortical acetylcholine effluxes was also examined under both conditions. Isoflurane had no influence on the glutamate and GABA efflux in the PH, whereas in the BF, it dose-dependently increased glutamate efflux and decreased GABA efflux. A transient increase in glutamate efflux at 1.0 MAC and a decrease in GABA at 0.5-1.5 MAC were observed in the S1BF. Isoflurane dose-dependently decreased acetylcholine efflux in the S1BF. Perfusion of the BF with AMPA increased acetylcholine efflux in the S1BF with electroencephalographic activation during 0.75 MAC isoflurane anesthesia, suggesting an inhibitory action of isoflurane on AMPA receptors in the BF. However, N-methyl-D-aspartate had no effect on these parameters. Isoflurane induces both excitatory and inhibitory actions in the cholinergic arousal system. The predominant inhibitory action of isoflurane over its excitatory action at the BF would result in the decrease in the acetylcholine efflux in the S1BF.

  6. Loss of SynDIG1 Reduces Excitatory Synapse Maturation But Not Formation In Vivo

    Science.gov (United States)

    Kaur, Inderpreet; Liu, Xiao-Bo; Kirk, Lyndsey M.; Speca, David J.; McMahon, Samuel A.; Zito, Karen

    2016-01-01

    Abstract Modification of the strength of excitatory synaptic connections is a fundamental mechanism by which neural circuits are refined during development and learning. Synapse Differentiation Induced Gene 1 (SynDIG1) has been shown to play a key role in regulating synaptic strength in vitro. Here, we investigated the role of SynDIG1 in vivo in mice with a disruption of the SynDIG1 gene rather than use an alternate loxP-flanked conditional mutant that we find retains a partial protein product. The gene-trap insertion with a reporter cassette mutant mice shows that the SynDIG1 promoter is active during embryogenesis in the retina with some activity in the brain, and postnatally in the mouse hippocampus, cortex, hindbrain, and spinal cord. Ultrastructural analysis of the hippocampal CA1 region shows a decrease in the average PSD length of synapses and a decrease in the number of synapses with a mature phenotype. Intriguingly, the total synapse number appears to be increased in SynDIG1 mutant mice. Electrophysiological analyses show a decrease in AMPA and NMDA receptor function in SynDIG1-deficient hippocampal neurons. Glutamate stimulation of individual dendritic spines in hippocampal slices from SynDIG1-deficient mice reveals increased short-term structural plasticity. Notably, the overall levels of PSD-95 or glutamate receptors enriched in postsynaptic biochemical fractions remain unaltered; however, activity-dependent synapse development is strongly compromised upon the loss of SynDIG1, supporting its importance for excitatory synapse maturation. Together, these data are consistent with a model in which SynDIG1 regulates the maturation of excitatory synapse structure and function in the mouse hippocampus in vivo.

  7. On how correlations between excitatory and inhibitory synaptic inputs maximize the information rate of neuronal firing

    Directory of Open Access Journals (Sweden)

    Pavel Anatolyevich Puzerey

    2014-06-01

    Full Text Available Cortical neurons receive barrages of excitatory and inhibitory inputs which are not independent, as network structure and synaptic kinetics impose statistical correlations. Experiments in vitro and in vivo have demonstrated correlations between inhibitory and excitatory synaptic inputs in which inhibition lags behind excitation in cortical neurons. This delay arises in feed-forward inhibition circuits and ensures that coincident excitation and inhibition do not preclude neuronal firing. Conversely, inhibition that is too delayed broadens neuronal integration times, thereby diminishing spike-time precision and increasing the firing frequency. This led us to hypothesize that the correlation between excitatory and inhibitory synaptic inputs modulates the encoding of information of neural spike trains. We tested this hypothesis by investigating the effect of such correlations on the information rate (IR of spike trains using the Hodgkin-Huxley model in which both synaptic and membrane conductances are stochastic. We investigated two different synaptic input regimes: balanced synaptic conductances and balanced currents. Our results show that correlations arising from the synaptic kinetics, tau, and millisecond lags, delta, of inhibition relative to excitation strongly affect the IR of spike trains. In the regime of balanced synaptic currents, for short time lags (delta ~ 1 ms there is an optimal tau that maximizes the IR of the postsynaptic spike train. Given the short time scales for monosynaptic inhibitory lags and synaptic decay kinetics reported in cortical neurons under physiological contexts, we propose that feed-forward inhibition in cortical circuits is poised to maximize the rate of information transfer between cortical neurons. Our results also provide a possible explanation for how certain drugs and genetic mutations affecting the synaptic kinetics can deteriorate information processing in the brain.

  8. Discovery of the first selective inhibitor of excitatory amino acid transporter subtype 1

    DEFF Research Database (Denmark)

    Jensen, Anders Asbjørn; Erichsen, Mette Navy; Nielsen, Christina Wøhlk

    2009-01-01

    The discovery of the first class of subtype-selective inhibitors of the human excitatory amino acid transporter subtype 1 (EAAT1) and its rat orthologue GLAST is reported. An opening structure-activity relationship of 25 analogues is presented that addresses the influence of substitutions at the ......- and 7-positions of the parental skeleton 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile. The most potent analogue 1o displays high nanomolar inhibitory activity at EAAT1 and a >400-fold selectivity over EAAT2 and EAAT3, making it a highly valuable pharmacological tool....

  9. Excitatory and inhibitory pathways modulate kainate excitotoxicity in hippocampal slice cultures

    DEFF Research Database (Denmark)

    Casaccia-Bonnefil, P; Benedikz, Eirikur; Rai, R;

    1993-01-01

    In organotypic hippocampal slice cultures, kainate (KA) specifically induces cell loss in the CA3 region while N-methyl-D-aspartate induces cell loss in the CA1 region. The sensitivity of slice cultures to KA toxicity appears only after 2 weeks in vitro which parallels the appearance of mossy...... fibers. KA toxicity is potentiated by co-application with the GABA-A antagonist, picrotoxin. These data suggest that the excitotoxicity of KA in slice cultures is modulated by both excitatory and inhibitory synapses....

  10. Neuronal chloride accumulation and excitatory GABA underlie aggravation of neonatal epileptiform activities by phenobarbital.

    Science.gov (United States)

    Nardou, Romain; Yamamoto, Sumii; Chazal, Geneviève; Bhar, Asma; Ferrand, Nadine; Dulac, Olivier; Ben-Ari, Yehezkel; Khalilov, Ilgam

    2011-04-01

    Phenobarbital produces its anti-epileptic actions by increasing the inhibitory drive of γ-aminobutyric acid. However, following recurrent seizures, γ-aminobutyric acid excites neurons because of a persistent increase of chloride raising the important issue of whether phenobarbital could aggravate persistent seizures. Here we compared the actions of phenobarbital on initial and established ictal-like events in an in vitro model of mirror focus. Using the in vitro three-compartment chamber preparation with the two hippocampi and their commissural fibres placed in three different chambers, kainate was applied to one hippocampus and phenobarbital contralaterally, either after one ictal-like event or after many recurrent ictal-like events that produce an epileptogenic mirror focus. Field, perforated patch and single-channel recordings were used to determine the effects of γ-aminobutyric acid and their modulation by phenobarbital, and alterations of the chloride cotransporters were investigated using sodium-potassium-chloride cotransporter 1 and potassium chloride cotransporter 2 antagonists, potassium chloride cotransporter 2 immunocytochemistry and sodium-potassium-chloride cotransporter 1 knockouts. Phenobarbital reduced initial ictal-like events and prevented the formation of a mirror focus when applied from the start. In contrast, phenobarbital aggravated epileptiform activities when applied after many ictal-like events by enhancing the excitatory actions of γ-aminobutyric acid due to increased chloride. The accumulation of chloride and the excitatory actions of γ-aminobutyric acid in mirror foci neurons are mediated by the sodium-potassium-chloride cotransporter 1 chloride importer and by downregulation and internalization of the chloride-exporter potassium-chloride cotransporter 2. Finally, concomitant applications of the sodium-potassium-chloride cotransporter 1 antagonist bumetanide and phenobarbital decreased excitatory actions of γ-aminobutyric acid and

  11. Diurnal rhythms in neurexins transcripts and inhibitory/excitatory synapse scaffold proteins in the biological clock.

    Directory of Open Access Journals (Sweden)

    Mika Shapiro-Reznik

    Full Text Available The neurexin genes (NRXN1/2/3 encode two families (α and β of highly polymorphic presynaptic proteins that are involved in excitatory/inhibitory synaptic balance. Recent studies indicate that neuronal activation and memory formation affect NRXN1/2/3α expression and alternative splicing at splice sites 3 and 4 (SS#3/SS#4. Neurons in the biological clock residing in the suprachiasmatic nuclei of the hypothalamus (SCN act as self-sustained oscillators, generating rhythms in gene expression and electrical activity, to entrain circadian bodily rhythms to the 24 hours day/night cycles. Cell autonomous oscillations in NRXN1/2/3α expression and SS#3/SS#4 exons splicing and their links to rhythms in excitatory/inhibitory synaptic balance in the circadian clock were explored. NRXN1/2/3α expression and SS#3/SS#4 splicing, levels of neurexin-2α and the synaptic scaffolding proteins PSD-95 and gephyrin (representing excitatory and inhibitory synapses, respectively were studied in mRNA and protein extracts obtained from SCN of C3H/J mice at different times of the 24 hours day/night cycle. Further studies explored the circadian oscillations in these components and causality relationships in immortalized rat SCN2.2 cells. Diurnal rhythms in mNRXN1α and mNRXN2α transcription, SS#3/SS#4 exon-inclusion and PSD-95 gephyrin and neurexin-2α levels were found in the SCN in vivo. No such rhythms were found with mNRXN3α. SCN2.2 cells also exhibited autonomous circadian rhythms in rNRXN1/2 expression SS#3/SS#4 exon inclusion and PSD-95, gephyrin and neurexin-2α levels. rNRXN3α and rNRXN1/2β were not expressed. Causal relationships were demonstrated, by use of specific siRNAs, between rNRXN2α SS#3 exon included transcripts and gephyrin levels in the SCN2.2 cells. These results show for the first time dynamic, cell autonomous, diurnal rhythms in expression and splicing of NRXN1/2 and subsequent effects on the expression of neurexin-2α and postsynaptic

  12. [Analysis of the therapeutic efficacy and prognosis for acute myeloid leukemia M2a patients treated by IA and DA regimens].

    Science.gov (United States)

    Wang, Fan; Yuan, Hai-Long; Duan, Xian-Lin; Wang, Lei; Cao, Hai-Zhou; Xu, Jian-Li; Qu, Jian-Hua

    2014-08-01

    This study was purposed to compare the therapeutic efficacy and prognosis of acute myeloid leukemia M2a (AML-M2a) patients treated by idarubicin (IDA) combined with cytarabine (Ara-C) (IA) and daunorubicin (DNR) combined cytarabine (Ara-C) (DA) regimens. The clinical data of 65 patients with AML-M2a in our hospital were collected from May 2009 to May 2013 and analyzed. The results indicated the complete remission in IA group was slightly higher than that in DA group, there was no statistically significant difference(P > 0.05); leukocyte minimum value in IA group [(0.58 ± 0.40)×10(9)/L] was obviously lower than that in DA group [(0.99 ± 0.67)×10(9)/L] (P DA group [(0.21 ± 0.16)×10(9)/L] (P DA group (9.17 ± 7.04)d (P DA group (21.45 months) (P DA regimen, the IA regimen can prolong the median survival time and has better long-term therapeutic efficacy, thus it can be used as the first chemotherapy regimen for treatment of AML-M2a.

  13. Changes in the response to excitatory antagonists, agonists, and spasmolytic agents in circular colonic smooth muscle strips from patients with diverticulosis.

    Science.gov (United States)

    Alvarez-Berdugo, D; Espín, F; Arenas, C; López, I; Clavé, P; Gallego, D

    2015-11-01

    Colonic samples from asymptomatic diverticulosis (DS) patients presented enhanced electrical field stimulation (EFS)-contractions, in an earlier study of ours, suggesting increased endogenous responses. The aim of this study was to explore changes in excitatory neuromuscular transmission and to assess the pharmacodynamics of spasmolytic agents in DS. Circular muscle strips from sigmoid colon of DS patients (n = 30; 69.5 ± 14.8 years) and controls (n = 32; 64.7 ± 16.2 years) were studied using organ baths to evaluate the direct effect of excitatory agonists (carbachol, neurokinin A [NKA] and substance P [SP]), and the effect of antagonists (atropine and NK2 antagonist GR94800) and spasmolytic drugs (otilonium bromide [OB] and N-butyl-hyoscine) on the contractions induced by EFS-stimulation of excitatory motorneurons. qRT-PCR was also performed to compare mRNA expression of M2 , M3 , NK2 receptors and L-type calcium channels. Contractions to carbachol (Emax : 663.7 ± 305.6% control vs 2698.0 ± 439.5% DS; p < 0.0005) and NKA (Emax : 387.8 ± 35.6% vs 1102.0 ± 190.1%; p < 0.0005) were higher in DS group, without differences for SP. Higher potency for DS patients was observed in the concentration-response curves for atropine (pIC50  = 8.56 ± 0.15 control vs pIC50  = 9.95 ± 0.18 DS group; p < 0.005) and slightly higher for GR94800 (pIC50  = 7.21 ± 0.18 control vs pIC50  = 7.97 ± 0.32 group; p < 0.0001). Lower efficacy (Emax ) and potency (pIC50 ) was observed for spasmolytic drugs in DS, whereas no differences were found regarding the relative expression of the receptors evaluated between groups. The greater response to cholinergic and tachykinergic agonists and greater potency for muscarinic and NK2 antagonists observed in DS might play a role in the spasticity found in diverticular disease. © 2015 John Wiley & Sons Ltd.

  14. Clinical outcome and imaging changes after intraarticular (IA) application of etanercept or methylprednisolone in rheumatoid arthritis: Magnetic resonance imaging and ultrasound-Doppler show no effect of IA injections in the wrist after 4 weeks

    DEFF Research Database (Denmark)

    Boesen, M.; Boesen, L.; Jensen, K.E.

    2008-01-01

    Objective. To assess the magnetic resonance imaging (MRI) and ultrasound (US) changes in the wrist of patients with rheumatoid arthritis (RA) 4 weeks after an US guided intraarticular (IA) injection. Methods. Contrast enhanced MRI and US-Doppler were performed at baseline and 4 weeks after IA...... injection of either 40 mg methylprednisolone (n = 12) or 25 mg etanercept (n = 13) in 25 patients with RA taking disease modifying antirheumatic drugs with a therapy-resistant wrist joint. All injections were US guided. Results. There was an improvement in swollen target joint score (p ...-29) in the total group was unchanged after 4 weeks (p = 0.13), whereas MRI erosion score increased in the total group from baseline, 17.88 (range 7-40), to 4 weeks, 18.25 (range 7-40) (p

  15. Interpreting the near-infrared spectra of the 'golden standard' Type Ia supernova 2005cf

    Science.gov (United States)

    Gall, E. E. E.; Taubenberger, S.; Kromer, M.; Sim, S. A.; Benetti, S.; Blanc, G.; Elias-Rosa, N.; Hillebrandt, W.

    2012-12-01

    We present nine near-infrared (NIR) spectra of supernova (SN) 2005cf at epochs from -10 to +42 d with respect to B-band maximum, complementing the existing excellent data sets available for this prototypical Type Ia SN at other wavelengths. The spectra show a time evolution and spectral features characteristic of normal Type Ia SNe, as illustrated by a comparison with SNe 1999ee, 2002bo and 2003du. The broad-band spectral energy distribution (SED) of SN 2005cf is studied in combined ultraviolet (UV), optical and NIR spectra at five epochs between ˜8 d before and ˜10 d after maximum light. We also present synthetic spectra of the hydrodynamic explosion model W7, which reproduce the key properties of SN 2005cf not only at UV-optical as previously reported, but also at NIR wavelengths. From the radiative-transfer calculations we infer that fluorescence is the driving mechanism that shapes the SED of SNe Ia. In particular, the NIR part of the spectrum is almost devoid of absorption features, and instead dominated by fluorescent emission of both iron-group material and intermediate-mass elements at pre-maximum epochs, and pure iron-group material after maximum light. A single P-Cygni feature of Mg II at early epochs and a series of relatively unblended Co II lines at late phases allow us to constrain the regions of the ejecta in which the respective elements are abundant. Based on observations collected at European Southern Observatory, Paranal. Program ID 075.D-0823(B).

  16. Sampling the probability distribution of Type Ia Supernova lightcurve parameters in cosmological analysis

    Science.gov (United States)

    Dai, Mi; Wang, Yun

    2016-06-01

    In order to obtain robust cosmological constraints from Type Ia supernova (SN Ia) data, we have applied Markov Chain Monte Carlo (MCMC) to SN Ia lightcurve fitting. We develop a method for sampling the resultant probability density distributions (pdf) of the SN Ia lightcuve parameters in the MCMC likelihood analysis to constrain cosmological parameters, and validate it using simulated data sets. Applying this method to the `joint lightcurve analysis (JLA)' data set of SNe Ia, we find that sampling the SN Ia lightcurve parameter pdf's leads to cosmological parameters closer to that of a flat Universe with a cosmological constant, compared to the usual practice of using only the best-fitting values of the SN Ia lightcurve parameters. Our method will be useful in the use of SN Ia data for precision cosmology.

  17. Acquisition of the Army Tactical Missile System Anti-Personnel/Anti-Materiel Block IA Program

    National Research Council Canada - National Science Library

    1998-01-01

    The Army Tactical Missile System Anti-PersonnellAnti-Materiel Block IA missile (Block IA) is a ground-launched missile system consisting of a surface-to-surface guided missile with an anti-personnel/anti-materiel warhead...

  18. Data of evolutionary structure change: 1ATIA-2Q5IA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1ATIA-2Q5IA 1ATI 2Q5I A A AASSLDELVALCKRRGFIFQSSEIYGGLQGVYDYGPLGV...--------NWTPPRYFNMMFQDLRGPRGGRGLLAYLRPETAQGIFVNFKNVLDATSRKLGFGIAQIGKAFRNEITPRNFIFRVREFEQMEIEYFVRPGE---------...------------------------DEYW--------HRY-WVEERLKWWQEMGLSRENLVPYQQPPESSAHYAKATVDILYRFPHGSLELEGIA...D> 0 1ATI A 1ATIA A 2Q5IA VDDSSGSIGRR

  19. The Role of Variations of Central Density Of White Dwarf Progenitors Upon Type Ia Supernovae

    CERN Document Server

    Fisher, R; Jordan, G; Lamb, D

    2010-01-01

    The discovery of the accelerated expansion of the universe using Type Ia supernovae (SNe Ia) has stimulated a tremendous amount of interest in the use of SNe Type Ia events as standard cosmological candles, and as a probe of the fundamental physics of dark energy. Recent observations of SNe Ia have indicated a significant population difference depending on the host galaxy. These observational findings are consistent with SNe Ia Ni-56 production in star-forming spiral galaxies some 0.1 solar masses higher - and therefore more luminous than in elliptical galaxies. We present recent full-star, 3D simulations of Type Ia supernovae which may help explain the nature of this systematic variation in SNe Ia luminosities, as well as the nature of the Ia explosion mechanism. These insights may in turn eventually shed light on the mystery of dark energy itself.

  20. Near-infrared absolute magnitudes of Type Ia Supernovae

    Science.gov (United States)

    Avelino, Arturo; Friedman, Andrew S.; Mandel, Kaisey; Kirshner, Robert; Challis, Peter

    2017-01-01

    Type Ia Supernovae light curves (SN Ia) in the near infrared (NIR) exhibit low dispersion in their peak luminosities and are less vulnerable to extinction by interstellar dust in their host galaxies. The increasing number of high quality NIR SNe Ia light curves, including the recent CfAIR2 sample obtained with PAIRITEL, provides updated evidence for their utility as standard candles for cosmology. Using NIR YJHKs light curves of ~150 nearby SNe Ia from the CfAIR2 and CSP samples, and from the literature, we determine the mean value and dispersion of the absolute magnitude in the range between -10 to 50 rest-frame days after the maximum luminosity in B band. We present the mean light-curve templates and Hubble diagram for YJHKs bands. This work contributes to a firm local anchor for supernova cosmology studies in the NIR which will help to reduce the systematic uncertainties due to host galaxy dust present in optical-only studies. This research is supported by NSF grants AST-156854, AST-1211196, Fundacion Mexico en Harvard, and CONACyT.

  1. 75 FR 32341 - Import Administration IA ACCESS Pilot Program

    Science.gov (United States)

    2010-06-08

    ... International Trade Administration 19 CFR Part 351 Import Administration IA ACCESS Pilot Program AGENCY: Import... comments. SUMMARY: The Department of Commerce (the Department) is creating a pilot program to test an..., the Department is requesting comments from parties on this pilot program. DATES: Effective Date:...

  2. 75 FR 34960 - Import Administration IA ACCESS Pilot Program

    Science.gov (United States)

    2010-06-21

    ... ACCESS Pilot Program in the Federal Register at 75 FR 32341. The reference to the Docket No. ITA- 2010.... The Department publishes this notice to correct this number. Accordingly, in FR Doc. 2010-13733, at... International Trade Administration 19 CFR Part 351 Import Administration IA ACCESS Pilot Program AGENCY:...

  3. 77 FR 42427 - Amendment of Class E Airspace; Grinnell, IA

    Science.gov (United States)

    2012-07-19

    ...) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Grinnell, IA AGENCY:...

  4. 78 FR 51262 - Iowa Disaster Number IA-00054

    Science.gov (United States)

    2013-08-20

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00054 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  5. 75 FR 65390 - Iowa Disaster Number IA-00024

    Science.gov (United States)

    2010-10-22

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 5. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of...

  6. 76 FR 80446 - Iowa Disaster Number IA-00033

    Science.gov (United States)

    2011-12-23

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00033 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of...

  7. 75 FR 52048 - Iowa Disaster Number IA-00024

    Science.gov (United States)

    2010-08-24

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of...

  8. 75 FR 57996 - Iowa Disaster Number IA-00026

    Science.gov (United States)

    2010-09-23

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 4. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  9. 75 FR 58451 - Iowa Disaster Number IA-00024

    Science.gov (United States)

    2010-09-24

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 3. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of...

  10. 75 FR 17178 - Iowa Disaster Number IA-00023

    Science.gov (United States)

    2010-04-05

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00023 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  11. 75 FR 59750 - Iowa Disaster Number IA-00026

    Science.gov (United States)

    2010-09-28

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 5. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  12. 76 FR 75447 - Amendment of Class E Airspace; Centerville, IA

    Science.gov (United States)

    2011-12-02

    ... E airspace for the Centerville, IA, area. (76 FR 53358) Docket No. FAA-2011-0830. Interested parties... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec....

  13. 75 FR 57997 - Iowa Disaster Number IA-00024

    Science.gov (United States)

    2010-09-23

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 2. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of...

  14. 76 FR 56863 - Iowa Disaster Number IA-00036

    Science.gov (United States)

    2011-09-14

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00036 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  15. 75 FR 57088 - Iowa Disaster Number IA-00026

    Science.gov (United States)

    2010-09-17

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 3. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  16. 75 FR 23581 - Amendment of Class E Airspace; Emmetsburg, IA

    Science.gov (United States)

    2010-05-04

    ..., IA, reconfiguring controlled airspace at Emmetsburg Municipal Airport (75 FR 6592) Docket No. FAA... a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  17. 75 FR 51506 - Iowa Disaster Number IA-00026

    Science.gov (United States)

    2010-08-20

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  18. 78 FR 53492 - Iowa Disaster Number IA-00053

    Science.gov (United States)

    2013-08-29

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00053 AGENCY: U.S. Small Business Administration. Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only...

  19. 75 FR 62897 - Iowa Disaster Number IA-00024

    Science.gov (United States)

    2010-10-13

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 4. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of...

  20. 78 FR 38781 - Iowa Disaster Number IA-00052

    Science.gov (United States)

    2013-06-27

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster Number IA-00052 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  1. Diarréia por parasitas Parasites induced diarrheas

    Directory of Open Access Journals (Sweden)

    Maria Eugênia Farias Almeida Motta

    2002-08-01

    Full Text Available A diarréia é uma causa importante de morbimortalidade nos países em desenvolvimento. Os agentes etiológicos mais comuns são os vírus e as bactérias. Este artigo tem o objetivo de analisar a ocorrência de diarréia como manifestação clínica de parasitose. Discute-se quais os protozoários e os helmintos que podem causar diarréia, as bases científicas atuais que explicam os mecanismos fisiopatológicos que desencadeiam a diarréia, bem como os exames complementares e o tratamento adequado para cada parasita implicado.Diarrhea is an important cause of morbidity and mortality in developing countries. The most common etiological agents are viruses and bacteria. This article has the objective of analyzing diarrhea as a clinical symptom of parasitosis. Protozoa and helminthes that may cause diarrhea are discussed, current scientific basis clarifying the pathological and physiological mechanisms causing diarrhea as well as supplementary tests and adequate treatment for each parasite involved are focused.

  2. Cosmic Supernova Rate History and Type Ia Supernova Progenitors

    OpenAIRE

    Kobayashi, Chiaki; Nomoto, Ken'ichi; Tsujimoto, Takuji

    2001-01-01

    Adopting a single degenerate scenario for Type Ia supernova progenitors with the metallicity effect, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in spiral and elliptical galaxies, and compare with the recent observational data up to z ~ 0.55.

  3. Estimating Type Ia Supernova Metallicities Using Neural Networks

    Science.gov (United States)

    Villar, V. Ashley

    2017-01-01

    Normal Type Ia supernovae (SNe) can be used as standardizable candles because their progenitors, white dwarfs, are a fairly homogenous class of objects. However, intrinsic variability in these events arise from a number of factors, including metallicity. Recent studies have investigated the effects of metallicity on Type Ia SNe observables from both a theoretical approach, by tuning model metallicity to analyze spectral features, and an observational approach, by studying the effect of host metallicity on light curves. In this work, we take a new, data-driven approach to the problem. Inspired by the success of neural networks in the field of image processing, we aim to estimate the metallicities of Type Ia SNe progenitors from their near-maximum spectra using feed-forward neural networks. We first collect a sample of near-maximum Type Ia SNe spectra from the literature to be smoothed and down-sampled. We then estimate the metallicities of the SNe hosts using the B-band magnitudes. We build a multilayer perceptron to generate a model that takes as input the down-sampled spectra and returns a scalar metallicity. Finally, we discuss basic considerations to be taken when working with spectral (as opposed to image) data using neural networks.

  4. Tax accounting - IFRS IAS 12: Voor accountants, controllers en fiscalisten

    NARCIS (Netherlands)

    Naarding, E.W.J.; Langendijk, H.P.A.J.

    2010-01-01

    Deel 7 van de reeks 'Tax Assurance in beeld' is een werkboek dat vraagstukken bevat om de technische aspecten van IAS 12 Income Taxes van de International Accounting Standards Board (IASB) te oefenen. Het boek is bedoeld voor accountants, controllers en fiscalisten die zich willen bekwamen in de tec

  5. Type Ia Supernova Color Curves: Disentangling Intrinsic Variations from Dust

    Science.gov (United States)

    Bouzid, Samia; McCully, C.; Jha, S.

    2012-01-01

    Type Ia supernovae (SNe Ia) are important cosmological tools based on their use as "standard candles": as objects of similar intrinsic luminosity, their variations in apparent brightness are a reliable indication of relative distance. The more accurately we can measure and correct for variations in SN Ia brightness, the more precisely we can determine cosmological distances and place constraints on cosmological parameters including the Hubble constant and the nature of dark energy. Corrections for dust along the line of sight to the SN are usually based on its reddening effect; however, recent studies have shown that the relationship between extinction and reddening of SN light curves does not match canonical values for standard, Milky Way-like dust. It is likely that color variations intrinsic to the SNe themselves are confounding our ability to independently determine the dust extinction and reddening. Using ground-based photometry of several hundred SNe from the published literature, we present an analysis that attempts to disentangle the effects of dust and intrinsic color variations by looking at the time dependence of SNe Ia colors, controlling for light curve shape properties by empirically matching similar objects.

  6. Nucleosynthesis in type Ia supernovae driven by asymmetric thermonuclear ignition

    Science.gov (United States)

    Maeda, Keiichi

    2012-11-01

    Type Ia Supernovae (SNe Ia) are believed to be thermonuclear explosions of a white dwarf. They can be used as mature cosmological standardized candles, leading to the discovery of the accelerating expansion of the Universe. However, the explosion mechanism has not yet been fully clarified. In this paper, we first present nucleosynthetic features of a leading explosion scenario, namely a delayed-detonation scenario. Based on this, we propose a new and strong observational constraint on the explosion mechanism through emission lines from neutron-rich Fe-peaks. Especially, we show that an asymmetry in the explosion is likely a generic feature. We further argue that the diversity arising from various viewing angles can be an origin of observational diversities of SNe Ia seen in their spectral features (suspected possible biases in cosmology) and colors (related to the extinction estimate in cosmology). Using these new insights could open up a possibility of using SNe Ia as more precise distance indicators than currently employed.

  7. Type Ia Supernova as Standard Candles in the Near Infrared

    Science.gov (United States)

    Wood-Vasey, Michael; Garnavich, Peter; Matheson, Thomas; Jha, Saurabh; Rest, Armin; Allen, Lori

    2011-08-01

    We propose to observe 15 SNeIa in the near infrared (NIR) with WHIRC on the WIYN telescope during 12 nights of bright time in 2011B. These observations will create an infrared Hubble diagram extending to z~0.1 to verify recent evidence that SNIa are excellent standard candles in the NIR. We will observe 15 SNeIa at 0.02color evolution in the near infrared where dust extinction is significantly reduced. In addition these NIR data will allow us to (1) explore the recent correlation between optical luminosity and host galaxy mass; (2) improve our understanding of intrinsic colors of SNeIa, (3) and study the nature of dust in galaxies beyond our Milky Way. Our ideal observing plan would consist of nights spaced every three days in each of four consecutive lunations in 2011B. This is a pilot proposal. If successful, this project will lead to a larger survey to obtain NIR luminosity distances to 100 SNeIa out to z<0.1 to provide a solid anchor for measuring luminosity distances in the Universe. We are not asking for long-term status at this time.

  8. Could there be a hole in type Ia supernovae?

    Energy Technology Data Exchange (ETDEWEB)

    Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

    2004-04-23

    In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity.

  9. Neutrinos from Type Ia Supernovae: The Gravitationally Confined Detonation Scenario

    CERN Document Server

    Wright, Warren P; Ohlmann, Sebastian T; Roepke, Friedrich K; Scholberg, Kate; Seitenzahl, Ivo R

    2016-01-01

    Despite their use as cosmological distance indicators and their importance in the chemical evolution of Galaxies, the unequivocal identification of the progenitor systems and explosion mechanism of normal Type Ia supernova (SN Ia) remains elusive. The leading hypothesis is that such a supernova is a thermonuclear explosion of a carbon-oxygen white dwarf but the exact explosion mechanism is still a matter of debate. Observation of a Galactic SN Ia would be of immense value in answering the many open questions related to these events. One potentially useful source of information about the explosion mechanism and progenitor is the neutrino signal. In this paper we compute the expected neutrino signal from a Gravitationally Confined Detonation (GCD) explosion scenario for a SN~Ia and show how the flux at Earth contains features in time and energy unique to this scenario. We then calculate the expected event rates in the Super-K, Hyper-K, JUNO, DUNE, and IceCube detectors and find both Hyper-K and IceCube would se...

  10. 75 FR 76294 - Radio Broadcasting Services: Pacific Junction, IA

    Science.gov (United States)

    2010-12-08

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 Radio Broadcasting Services: Pacific Junction, IA AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: The staff deletes FM Channel 299C2 at Pacific Junction,...

  11. The circumstellar environment of pre-SN Ia systems

    CERN Document Server

    Harvey, E; Boumis, P; Kopsacheili, M; Akras, S; Sabin, L; Jurkic, T

    2016-01-01

    Here we explore the possible preexisting circumstellar debris of supernova type Ia systems. Classical, symbiotic and recurrent novae all accrete onto roughly solar mass white dwarfs from main sequence or Mira type companions and result in thermonuclear runaways and expulsion of the accreted material at high velocity. The expelled material forms a fast moving shell that eventually slows to planetary nebula expansion velocities within several hundred years. All such systems are recurrent and thousands of shells (each of about 0.001 Mo) snow plough into the environment. As these systems involve common envelope binaries the material is distributed in a non-spherical shell. These systems could be progenitors of some SN Ia and thus explode into environments with large amounts of accumulated gas and dust distributed in thin non-spherical shells. Such shells should be observable around 100 years after a SN Ia event in a radio flash as the SN Ia debris meets that of the ejected material of the systems previous incarna...

  12. On Spectral Line Profiles in Type Ia Supernova Spectra

    CERN Document Server

    Foley, Ryan J

    2013-01-01

    We present a detailed analysis of spectral line profiles in Type Ia supernova (SN Ia) spectra. We focus on the feature at ~3500 - 4000 A, which is commonly thought to be caused by blueshifted absorption of Ca H&K. Unlike some other spectral features in SN Ia spectra, this feature often has two overlapping (blue and red) components. It is accepted that the red component comes from photospheric calcium. However, it has been proposed that the blue component is caused by either high-velocity calcium (from either abundance or density enhancements above the photosphere of the SN) or Si II 3858. By looking at multiple data sets and model spectra, we conclude that the blue component of the Ca H&K feature is caused by Si II 3858 for most SNe Ia. The strength of the Si II 3858 feature varies strongly with the light-curve shape of a SN. As a result, the velocity measured from a single-Gaussian fit to the full line profile correlates with light-curve shape. The velocity of the Ca H&K component of the profile ...

  13. 'Super-Chandrasekhar' Type Ia Supernovae at nebular epochs

    CERN Document Server

    Taubenberger, Stefan; Hachinger, Stephan; Mazzali, Paolo A; Benetti, Stefano; Nugent, Peter E; Scalzo, Richard A; Pakmor, Rüdiger; Stanishev, Vallery; Spyromilio, Jason; Bufano, Filomena; Sim, Stuart A; Leibundgut, Bruno; Hillebrandt, Wolfgang

    2013-01-01

    We present a first systematic comparison of superluminous Type Ia supernovae (SNe Ia) at late epochs, including previously unpublished photometric and spectroscopic observations of SN 2007if, SN 2009dc and SNF20080723-012. Photometrically, the objects of our sample show a diverse late-time behaviour, some of them fading quite rapidly after a light-curve break at ~150-200d. The latter is likely the result of flux redistribution into the infrared, possibly caused by dust formation, rather than a true bolometric effect. Nebular spectra of superluminous SNe Ia are characterised by weak or absent [Fe III] emission, pointing at a low ejecta ionisation state as a result of high densities. To constrain the ejecta and 56Ni masses of superluminous SNe Ia, we compare the observed bolometric light curve of SN 2009dc with synthetic model light curves, focusing on the radioactive tail after ~60d. Models with enough 56Ni to explain the light-curve peak by radioactive decay, and at the same time sufficient mass to keep the e...

  14. On the Relationship between Circumplexes: Affect and Wiggins' IAS

    Science.gov (United States)

    Yik, Michelle S. M.; Russell, James A.

    2004-01-01

    This article offers a new method to describe the relationship between two circumplexes, illustrated empirically with Wiggins' (1995) Interpersonal Adjective Scales (IAS) and Yik, Russell, and Steiger's (2004) 12-Point Affect Circumplex Scales (12-PACS). Michael Browne's CIRCUM-extension procedure was used to place each circumplex within the other.…

  15. Type Ia supernovae from exploding oxygen-neon white dwarfs

    CERN Document Server

    Marquardt, Kai S; Ruiter, Ashley J; Seitenzahl, Ivo R; Ohlmann, Sebastian T; Kromer, Markus; Pakmor, Ruediger; Roepke, Friedrich K

    2015-01-01

    The progenitor problem of Type Ia supernovae (SNe Ia) is still unsolved. Most of these events are thought to be explosions of carbon-oxygen (CO) white dwarfs (WDs), but for many of the explosion scenarios, particularly those involving the externally triggered detonation of a sub-Chandrasekhar mass WD (sub-M Ch WD), there is also a possibility of having an oxygen-neon (ONe) WD as progenitor. We simulate detonations of ONe WDs and calculate synthetic observables from these models. The results are compared with detonations in CO WDs of similar mass and observational data of SNe Ia. We perform hydrodynamic explosion simulations of detonations in initially hydrostatic ONe WDs for a range of masses below the Chandrasekhar mass (M Ch), followed by detailed nucleosynthetic postprocessing with a 384-isotope nuclear reaction network. The results are used to calculate synthetic spectra and light curves, which are then compared with observations of SNe Ia. We also perform binary evolution calculations to determine the nu...

  16. Tax accounting - IFRS IAS 12 : Voor accountants, controllers en fiscalisten

    NARCIS (Netherlands)

    Naarding, E.; Langendijk, H.P.A.J.

    2010-01-01

    Deel 7 van de reeks 'Tax Assurance in beeld' is een werkboek dat vraagstukken bevat om de technische aspecten van IAS 12 Income Taxes van de International Accounting Standards Board (IASB) te oefenen. Het boek is bedoeld voor accountants, controllers en fiscalisten die zich willen bekwamen in de tec

  17. Post-traumatic headache Cefaléia após traumatismo cranioencefálico

    Directory of Open Access Journals (Sweden)

    Hugo André de Lima Martins

    2009-03-01

    Full Text Available The onset of post-traumatic headache (PTC occurs in the first seven days after trauma, according to the International Headache Society (IHS classification. The objective of this study was to evaluate the several forms of headache that appear after mild head injury (HI and time interval between the HI and the onset of pain. We evaluated 41 patients with diagnosis of mild HI following the IHS criteria. Migraine without aura and the chronic tension-type headache were the most prevalent groups, occurring in 16 (39% and 14 (34.1% patients respectively. The time interval between HI and the onset of headache was less than seven days in 20 patients (48.7% and longer than 30 days in 10 (24.3% patients. The results suggest that PTC may arise after a period longer than is accepted at the present by the IHS.O início da cefaléia pós-traumática (CPT ocorre dentro de sete dias após o trauma, de acordo com a classificação da Sociedade Internacional de Cefaléia (SIC. O objetivo deste estudo foi avaliar as diversas formas de cefaléia que surgem após o traumatismo cranioencefálico (TCE leve e o intervalo de tempo entre o TCE e o início da dor. Foram avaliados 41 pacientes com diagnóstico de cefaléia pós-traumática leve segundo os critérios da SIC. Migrânea sem aura e cefaléia do tipo tensional crônica foram os tipos de cefaléia mais comuns, ocorrendo em 16 (39% e 14 (34,1% dos pacientes respectivamente. O intervalo de tempo entre o TCE e o início da cefaléia foi menor que sete dias em 20 pacientes (48% e maior que 30 dias em 10 (24,3% pacientes. Estes resultados sugerem que a CPT pode surgir após período maior do que é aceito atualmente pela SIC.

  18. The core-degenerate scenario for the progenitors of Type Ia supernovae

    Science.gov (United States)

    Wang, B.; Zhou, W.-H.; Zuo, Z.-Y.; Li, Y.-B.; Luo, X.; Zhang, J.-J.; Liu, D.-D.; Wu, C.-Y.

    2017-02-01

    The origin of the progenitors of Type Ia supernovae (SNe Ia) is still uncertain. The core-degenerate (CD) scenario has been proposed as an alternative way for the production of SNe Ia. In this scenario, SNe Ia are formed at the final stage of common-envelope evolution from a merger of a carbon-oxygen white dwarf (CO WD) with the CO core of an asymptotic giant branch companion. However, the birthrates of SNe Ia from this scenario are still not well determined. In this work, we performed a detailed investigation on the CD scenario based on a binary population synthesis approach. The SN Ia delay times from this scenario are basically in the range of 90-2500 Myr, mainly contributing to the observed SNe Ia with short and intermediate delay times, although this scenario can also produce some old SNe Ia. Meanwhile, our work indicates that the Galactic birthrates of SNe Ia from this scenario are not more than 20 per cent of total SNe Ia due to more careful treatment of mass transfer. Although the SN Ia birthrates in this work are lower than those in Ilkov & Soker, the CD scenario cannot be ruled out as a viable mechanism for the formation of SNe Ia. Especially, SNe Ia with circumstellar material from this scenario contribute to 0.7-10 per cent of total SNe Ia, which means that the CD scenario can reproduce the observed birthrates of SNe Ia like PTF 11kx. We also found that SNe Ia happen systemically earlier for a high value of metallicity and their birthrates increase with metallicity.

  19. Structural characteristics of an antigen required for its interaction with Ia and recognition by T cells

    DEFF Research Database (Denmark)

    Sette, A; Buus, S; Colon, S;

    1987-01-01

    A detailed analysis of the residues within an immunogenic peptide that endow it with the capacity to interact with Ia and to be recognized by T cells is presented. Ia interacts with only a few of the peptide residues and overall exhibits a very broad specificity. Some residues appear to interact...... both with Ia and with T cells, leading to a model in which a peptide antigen is 'sandwiched' between Ia and the T-cell receptor....

  20. Excitatory and inhibitory synaptic mechanisms at the first stage of integration in the electroreception system of the shark.

    Science.gov (United States)

    Rotem, Naama; Sestieri, Emanuel; Hounsgaard, Jorn; Yarom, Yosef

    2014-01-01

    High impulse rate in afferent nerves is a common feature in many sensory systems that serve to accommodate a wide dynamic range. However, the first stage of integration should be endowed with specific properties that enable efficient handling of the incoming information. In elasmobranches, the afferent nerve originating from the ampullae of Lorenzini targets specific neurons located at the Dorsal Octavolateral Nucleus (DON), the first stage of integration in the electroreception system. Using intracellular recordings in an isolated brainstem preparation from the shark we analyze the properties of this afferent pathway. We found that stimulating the afferent nerve activates a mixture of excitatory and inhibitory synapses mediated by AMPA-like and GABAA receptors, respectively. The excitatory synapses that are extremely efficient in activating the postsynaptic neurons display unusual voltage dependence, enabling them to operate as a current source. The inhibitory input is powerful enough to completely eliminate the excitatory action of the afferent nerve but is ineffective regarding other excitatory inputs. These observations can be explained by the location and efficiency of the synapses. We conclude that the afferent nerve provides powerful and reliable excitatory input as well as a feed-forward inhibitory input, which is partially presynaptic in origin. These results question the cellular location within the DON where cancelation of expected incoming signals occurs.

  1. Excitatory and inhibitory synaptic mechanisms at the first stage of integration in the electroreception system of the shark

    Directory of Open Access Journals (Sweden)

    Naama eRotem

    2014-03-01

    Full Text Available High impulse rate in afferent nerves is a common feature in many sensory systems that serve to accommodate a wide dynamic range. However, the first stage of integration should be endowed with specific properties that enable efficient handling of the incoming information. In elasmobranches, the afferent nerve originating from the ampullae of Lorenzini targets specific neurons located at the Dorsal Octavolateral Nucleus (DON, the first stage of integration in the electroreception system. Using intracellular recordings in an isolated brainstem preparation from the shark we analyze the properties of this afferent pathway. We found that stimulating the afferent nerve activates a mixture of excitatory and inhibitory synapses mediated by AMPA-like and GABAA receptors, respectively. The excitatory synapses that are extremely efficient in activating the postsynaptic neurons display unusual voltage dependence, enabling them to operate as a current source. The inhibitory input is powerful enough to completely eliminate the excitatory action of the afferent nerve but is ineffective regarding other excitatory inputs. These observations can be explained by the location and efficiency of the synapses. We conclude that the afferent nerve provides powerful and reliable excitatory input as well as a feed-forward inhibitory input, which is partially presynaptic in origin. These results question the cellular location within the dorsal octavolateral nucleus where cancelation of expected incoming signals occurs.

  2. Dynamical Responses to External Stimuli for Both Cases of Excitatory and Inhibitory Synchronization in A Complex Neuronal Network

    CERN Document Server

    Kim, Sang-Yoon

    2016-01-01

    For studying how dynamical responses to external stimuli depend on the synaptic-coupling type, we consider two types of excitatory and inhibitory synchronization (i.e., synchronization via synaptic excitation and inhibition) in complex small-world networks of excitatory regular spiking (RS) pyramidal neurons and inhibitory fast spiking (FS) interneurons. For both cases of excitatory and inhibitory synchronization, effects of synaptic couplings on dynamical responses to external time-periodic stimuli $S(t)$ (applied to a fraction of neurons) are investigated by varying the driving amplitude $A$ of $S(t)$. Stimulated neurons are phase-locked to external stimuli for both cases of excitatory and inhibitory couplings. On the other hand, the stimulation effect on non-stimulated neurons depends on the type of synaptic coupling. The external stimulus $S(t)$ makes a constructive effect on excitatory non-stimulated RS neurons (i.e., it causes external phase lockings in the non-stimulated sub-population), while $S(t)$ m...

  3. Group Based Interference Alignment

    CERN Document Server

    Ma, Yanjun; Chen, Rui; Yao, Junliang

    2010-01-01

    in $K$-user single-input single-output (SISO) frequency selective fading interference channels, it is shown that the achievable multiplexing gain is almost surely $K/2$ by using interference alignment (IA). However when the signaling dimensions is limited, allocating all the resource to all the users simultaneously is not optimal. According to this problem, a group based interference alignment (GIA) scheme is proposed and a search algorithm is designed to get the group patterns and the resource allocation among them. Analysis results show that our proposed scheme achieves a higher multiplexing gain when the resource is limited.

  4. 75 FR 26709 - Clarke County Water Supply Project, Clarke County, IA

    Science.gov (United States)

    2010-05-12

    ... Natural Resources Conservation Service Clarke County Water Supply Project, Clarke County, IA AGENCY... Moines, IA 50309-2180, telephone: 515-284- 4769. SUPPLEMENTARY INFORMATION: A Notice of Intent (NOI) to... http://www.ia.nrcs.usda.gov . A map of the Clarke County Water Supply proposed study sites will also...

  5. 49 CFR 232.207 - Class IA brake tests-1,000-mile inspection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Class IA brake tests-1,000-mile inspection. 232... Class IA brake tests—1,000-mile inspection. (a) Except as provided in § 232.213, each train shall receive a Class IA brake test performed by a qualified person, as defined in § 232.5, at a location...

  6. Draft Genome Sequences of Streptococcus agalactiae Serotype Ia and III Isolates from Tilapia Farms in Thailand.

    Science.gov (United States)

    Areechon, Nontawith; Kannika, Korntip; Hirono, Ikuo; Kondo, Hidehiro; Unajak, Sasimanas

    2016-03-24

    Streptococcus agalactiaeserotypes Ia and III were isolated from infected tilapia in cage and pond culture farms in Thailand during 2012 to 2014, in which pathogenicity analysis demonstrated that serotype III showed higher virulence than serotype Ia. Here, we report the draft genome sequencing of piscineS. agalactiaeserotypes Ia and III.

  7. 76 FR 5472 - Establishment of Class E Airspace; New Hampton, IA

    Science.gov (United States)

    2011-02-01

    ... Center Heliport, New Hampton, IA. This action is necessary for the safety and management of IFR... Federal Aviation Administration 14 CFR Part 71 Establishment of Class E Airspace; New Hampton, IA AGENCY... airspace at New Hampton, IA, to accommodate new Area Navigation (RNAV) Standard Instrument...

  8. Integrated plasticity at inhibitory and excitatory synapses in the cerebellar circuit

    Directory of Open Access Journals (Sweden)

    Lisa eMapelli

    2015-05-01

    Full Text Available The way long-term potentiation (LTP and depression (LTD are integrated within the different synapses of brain neuronal circuits is poorly understood. In order to progress beyond the identification of specific molecular mechanisms, a system in which multiple forms of plasticity can be correlated with large-scale neural processing is required. In this paper we take as an example the cerebellar network , in which extensive investigations have revealed LTP and LTD at several excitatory and inhibitory synapses. Cerebellar LTP and LTD occur in all three main cerebellar subcircuits (granular layer, molecular layer, deep cerebellar nuclei and correspondingly regulate the function of their three main neurons: granule cells (GrCs, Purkinje cells (PCs and deep cerebellar nuclear (DCN cells. All these neurons, in addition to be excited, are reached by feed-forward and feed-back inhibitory connections, in which LTP and LTD may either operate synergistically or homeostatically in order to control information flow through the circuit. Although the investigation of individual synaptic plasticities in vitro is essential to prove their existence and mechanisms, it is insufficient to generate a coherent view of their impact on network functioning in vivo. Recent computational models and cell-specific genetic mutations in mice are shedding light on how plasticity at multiple excitatory and inhibitory synapses might regulate neuronal activities in the cerebellar circuit and contribute to learning and memory and behavioral control.

  9. Encoding of naturalistic stimuli by local field potential spectra in networks of excitatory and inhibitory neurons.

    Directory of Open Access Journals (Sweden)

    Alberto Mazzoni

    2008-12-01

    Full Text Available Recordings of local field potentials (LFPs reveal that the sensory cortex displays rhythmic activity and fluctuations over a wide range of frequencies and amplitudes. Yet, the role of this kind of activity in encoding sensory information remains largely unknown. To understand the rules of translation between the structure of sensory stimuli and the fluctuations of cortical responses, we simulated a sparsely connected network of excitatory and inhibitory neurons modeling a local cortical population, and we determined how the LFPs generated by the network encode information about input stimuli. We first considered simple static and periodic stimuli and then naturalistic input stimuli based on electrophysiological recordings from the thalamus of anesthetized monkeys watching natural movie scenes. We found that the simulated network produced stimulus-related LFP changes that were in striking agreement with the LFPs obtained from the primary visual cortex. Moreover, our results demonstrate that the network encoded static input spike rates into gamma-range oscillations generated by inhibitory-excitatory neural interactions and encoded slow dynamic features of the input into slow LFP fluctuations mediated by stimulus-neural interactions. The model cortical network processed dynamic stimuli with naturalistic temporal structure by using low and high response frequencies as independent communication channels, again in agreement with recent reports from visual cortex responses to naturalistic movies. One potential function of this frequency decomposition into independent information channels operated by the cortical network may be that of enhancing the capacity of the cortical column to encode our complex sensory environment.

  10. Remodeling and Tenacity of Inhibitory Synapses: Relationships with Network Activity and Neighboring Excitatory Synapses.

    Science.gov (United States)

    Rubinski, Anna; Ziv, Noam E

    2015-11-01

    Glutamatergic synapse size remodeling is governed not only by specific activity forms but also by apparently stochastic processes with well-defined statistics. These spontaneous remodeling processes can give rise to skewed and stable synaptic size distributions, underlie scaling of these distributions and drive changes in glutamatergic synapse size "configurations". Where inhibitory synapses are concerned, however, little is known on spontaneous remodeling dynamics, their statistics, their activity dependence or their long-term consequences. Here we followed individual inhibitory synapses for days, and analyzed their size remodeling dynamics within the statistical framework previously developed for glutamatergic synapses. Similar to glutamatergic synapses, size distributions of inhibitory synapses were skewed and stable; at the same time, however, sizes of individual synapses changed considerably, leading to gradual changes in synaptic size configurations. The suppression of network activity only transiently affected spontaneous remodeling dynamics, did not affect synaptic size configuration change rates and was not followed by the scaling of inhibitory synapse size distributions. Comparisons with glutamatergic synapses within the same dendrites revealed a degree of coupling between nearby inhibitory and excitatory synapse remodeling, but also revealed that inhibitory synapse size configurations changed at considerably slower rates than those of their glutamatergic neighbors. These findings point to quantitative differences in spontaneous remodeling dynamics of inhibitory and excitatory synapses but also reveal deep qualitative similarities in the processes that control their sizes and govern their remodeling dynamics.

  11. Cancer metastasis-suppressing peptide metastin upregulates excitatory synaptic transmission in hippocampal dentate granule cells.

    Science.gov (United States)

    Arai, Amy C; Xia, Yan-Fang; Suzuki, Erika; Kessler, Markus; Civelli, Olivier; Nothacker, Hans-Peter

    2005-11-01

    Metastin is an antimetastatic peptide encoded by the KiSS-1 gene in cancer cells. Recent studies found that metastin is a ligand for the orphan G-protein-coupled receptor GPR54, which is highly expressed in specific brain regions such as the hypothalamus and parts of the hippocampus. This study shows that activation of GPR54 by submicromolar concentrations of metastin reversibly enhances excitatory synaptic transmission in hippocampal dentate granule cells in a mitogen-activated protein (MAP) kinase-dependent manner. Synaptic enhancement by metastin was suppressed by intracellular application of the G-protein inhibitor GDP-beta-S and the calcium chelator BAPTA. Analysis of miniature excitatory postsynaptic currents (mEPSCs) revealed an increase in the mean amplitude but no change in event frequency. This indicates that GPR54 and the mechanism responsible for the increase in EPSCs are postsynaptic. Metastin-induced synaptic potentiation was abolished by 50 microM PD98059 and 20 microM U0126, two inhibitors of the MAP kinases ERK1 and ERK2. The effect was also blocked by inhibitors of calcium/calmodulin-dependent kinases and tyrosine kinases. RT-PCR experiments showed that both KiSS-1 and GPR54 are expressed in the hippocampal dentate gyrus. Metastin is thus a novel endogenous factor that modulates synaptic excitability in the dentate gyrus through mechanisms involving MAP kinases, which in turn may be controlled upstream by calcium-activated kinases and tyrosine kinases.

  12. Cultured networks of excitatory projection neurons and inhibitory interneurons for studying human cortical neurotoxicity.

    Science.gov (United States)

    Xu, Jin-Chong; Fan, Jing; Wang, Xueqing; Eacker, Stephen M; Kam, Tae-In; Chen, Li; Yin, Xiling; Zhu, Juehua; Chi, Zhikai; Jiang, Haisong; Chen, Rong; Dawson, Ted M; Dawson, Valina L

    2016-04-06

    Translating neuroprotective treatments from discovery in cell and animal models to the clinic has proven challenging. To reduce the gap between basic studies of neurotoxicity and neuroprotection and clinically relevant therapies, we developed a human cortical neuron culture system from human embryonic stem cells or human inducible pluripotent stem cells that generated both excitatory and inhibitory neuronal networks resembling the composition of the human cortex. This methodology used timed administration of retinoic acid to FOXG1(+) neural precursor cells leading to differentiation of neuronal populations representative of the six cortical layers with both excitatory and inhibitory neuronal networks that were functional and homeostatically stable. In human cortical neuronal cultures, excitotoxicity or ischemia due to oxygen and glucose deprivation led to cell death that was dependent on N-methyl-D-aspartate (NMDA) receptors, nitric oxide (NO), and poly(ADP-ribose) polymerase (PARP) (a cell death pathway called parthanatos that is distinct from apoptosis, necroptosis, and other forms of cell death). Neuronal cell death was attenuated by PARP inhibitors that are currently in clinical trials for cancer treatment. This culture system provides a new platform for the study of human cortical neurotoxicity and suggests that PARP inhibitors may be useful for ameliorating excitotoxic and ischemic cell death in human neurons.

  13. New players tip the scales in the balance between excitatory and inhibitory synapses

    Directory of Open Access Journals (Sweden)

    El-Husseini Alaa

    2005-03-01

    Full Text Available Abstract Synaptogenesis is a highly controlled process, involving a vast array of players which include cell adhesion molecules, scaffolding and signaling proteins, neurotransmitter receptors and proteins associated with the synaptic vesicle machinery. These molecules cooperate in an intricate manner on both the pre- and postsynaptic sides to orchestrate the precise assembly of neuronal contacts. This is an amazing feat considering that a single neuron receives tens of thousands of synaptic inputs but virtually no mismatch between pre- and postsynaptic components occur in vivo. One crucial aspect of synapse formation is whether a nascent synapse will develop into an excitatory or inhibitory contact. The tight control of a balance between the types of synapses formed regulates the overall neuronal excitability, and is thus critical for normal brain function and plasticity. However, little is known about how this balance is achieved. This review discusses recent findings which provide clues to how neurons may control excitatory and inhibitory synapse formation, with focus on the involvement of the neuroligin family and PSD-95 in this process.

  14. Excitatory and inhibitory neurotransmitters in the generation and degeneration of hippocampal neuroarchitecture.

    Science.gov (United States)

    Mattson, M P; Kater, S B

    1989-01-30

    The possibility that excitatory and inhibitory inputs to neurons can affect the generation and degeneration of neuroarchitecture was examined in hippocampal pyramidal neurons in isolated cell culture. Dendritic outgrowth and cell survival were directly monitored in neurons exposed to: the excitatory neurotransmitter glutamate, the inhibitory transmitter GABA, anticonvulsants or combinations of these agents. Glutamate caused a graded series of changes in pyramidal neuron cytoarchitecture: a selective inhibition in dendritic outgrowth and dendritic pruning was observed with subtoxic levels of glutamate while cell death was induced by higher levels. Low levels of GABA alone or in combination with diazepam, carbamazepine, phenobarbital or phenytoin were without effect on dendrite outgrowth while higher levels caused moderate reductions in outgrowth. Neither GABA nor the anticonvulsants affected cell survival. GABA plus diazepam, phenobarbital, carbamazepine and phenytoin each significantly reduced the dendritic regression and cell death normally caused by glutamate. Elevation of extracellular K+ to 50 mM caused dendritic regression and 100 mM K+ caused cell death; these effects were greatly reduced by GABA and anticonvulsants. The calcium channel blocker Co2+ prevented the dendritic regression and cell death caused by both glutamate and K+ indicating that calcium influx was required for the neuroarchitectural responses. Taken together, these results demonstrate that neurotransmitters and neuromodulatory drugs can have direct and interactive effects on both neurite outgrowth and cell survival. Such neurotransmitter actions may play roles in both the formation and degeneration of the neuronal circuits in which they participate in information coding.

  15. Intrinsic bursters increase the robustness of rhythm generation in an excitatory network.

    Science.gov (United States)

    Purvis, L K; Smith, J C; Koizumi, H; Butera, R J

    2007-02-01

    The pre-Botzinger complex (pBC) is a vital subcircuit of the respiratory central pattern generator. Although the existence of neurons with pacemaker-like bursting properties in this network is not questioned, their role in network rhythmogenesis is unresolved. Modeling is ideally suited to address this debate because of the ease with which biophysical parameters of individual cells and network architecture can be manipulated. We modeled the parameter variability of experimental data from pBC bursting pacemaker and nonpacemaker neurons using a modified version of our previously developed pBC neuron and network models. To investigate the role of pacemakers in networkwide rhythmogenesis, we simulated networks of these neurons and varied the fraction of the population made up of pacemakers. For each number of pacemaker neurons, we varied the amount of tonic drive to the network and measured the frequency of synchronous networkwide bursting produced. Both excitatory networks with all-to-all coupling and sparsely connected networks were explored for several levels of synaptic coupling strength. Networks containing only nonpacemakers were able to produce networkwide bursting, but with a low probability of bursting and low input and output ranges. Our results indicate that inclusion of pacemakers in an excitatory network increases robustness of the network by more than tripling the input and output ranges compared with networks containing no pacemakers. The largest increase in dynamic range occurs when the number of pacemakers in the network is greater than 20% of the population. Experimental tests of our model predictions are proposed.

  16. Asymmetric excitatory synaptic dynamics underlie interaural time difference processing in the auditory system.

    Directory of Open Access Journals (Sweden)

    Pablo E Jercog

    Full Text Available Low-frequency sound localization depends on the neural computation of interaural time differences (ITD and relies on neurons in the auditory brain stem that integrate synaptic inputs delivered by the ipsi- and contralateral auditory pathways that start at the two ears. The first auditory neurons that respond selectively to ITD are found in the medial superior olivary nucleus (MSO. We identified a new mechanism for ITD coding using a brain slice preparation that preserves the binaural inputs to the MSO. There was an internal latency difference for the two excitatory pathways that would, if left uncompensated, position the ITD response function too far outside the physiological range to be useful for estimating ITD. We demonstrate, and support using a biophysically based computational model, that a bilateral asymmetry in excitatory post-synaptic potential (EPSP slopes provides a robust compensatory delay mechanism due to differential activation of low threshold potassium conductance on these inputs and permits MSO neurons to encode physiological ITDs. We suggest, more generally, that the dependence of spike probability on rate of depolarization, as in these auditory neurons, provides a mechanism for temporal order discrimination between EPSPs.

  17. The Susd2 protein regulates neurite growth and excitatory synaptic density in hippocampal cultures.

    Science.gov (United States)

    Nadjar, Yann; Triller, Antoine; Bessereau, Jean-Louis; Dumoulin, Andrea

    2015-03-01

    Complement control protein (CCP) domains have adhesion properties and are commonly found in proteins that control the complement immune system. However, an increasing number of proteins containing CCP domains have been reported to display neuronal functions. Susd2 is a transmembrane protein containing one CCP domain. It was previously identified as a tumor-reversing protein, but has no characterized function in the CNS. The present study investigates the expression and function of Susd2 in the rat hippocampus. Characterization of Susd2 during development showed a peak in mRNA expression two weeks after birth. In hippocampal neuronal cultures, the same expression profile was observed at 15days in vitro for both mRNA and protein, a time consistent with synaptogenesis in our model. At the subcellular level, Susd2 was located on the soma, axons and dendrites, and appeared to associate preferentially with excitatory synapses. Inhibition of Susd2 by shRNAs led to decreased numbers of excitatory synaptic profiles, exclusively. Also, morphological parameters were studied on young (5DIV) developing neurons. After Susd2 inhibition, an increase in dendritic tree length but a decrease in axon elongation were observed, suggesting changes in adhesion properties. Our results demonstrate a dual role for Susd2 at different developmental stages, and raise the question whether Susd2 and other CCP-containing proteins expressed in the CNS could be function-related.

  18. Integrated plasticity at inhibitory and excitatory synapses in the cerebellar circuit.

    Science.gov (United States)

    Mapelli, Lisa; Pagani, Martina; Garrido, Jesus A; D'Angelo, Egidio

    2015-01-01

    The way long-term potentiation (LTP) and depression (LTD) are integrated within the different synapses of brain neuronal circuits is poorly understood. In order to progress beyond the identification of specific molecular mechanisms, a system in which multiple forms of plasticity can be correlated with large-scale neural processing is required. In this paper we take as an example the cerebellar network, in which extensive investigations have revealed LTP and LTD at several excitatory and inhibitory synapses. Cerebellar LTP and LTD occur in all three main cerebellar subcircuits (granular layer, molecular layer, deep cerebellar nuclei) and correspondingly regulate the function of their three main neurons: granule cells (GrCs), Purkinje cells (PCs) and deep cerebellar nuclear (DCN) cells. All these neurons, in addition to be excited, are reached by feed-forward and feed-back inhibitory connections, in which LTP and LTD may either operate synergistically or homeostatically in order to control information flow through the circuit. Although the investigation of individual synaptic plasticities in vitro is essential to prove their existence and mechanisms, it is insufficient to generate a coherent view of their impact on network functioning in vivo. Recent computational models and cell-specific genetic mutations in mice are shedding light on how plasticity at multiple excitatory and inhibitory synapses might regulate neuronal activities in the cerebellar circuit and contribute to learning and memory and behavioral control.

  19. The Balance of Excitatory and Inhibitory Synaptic Inputs for Coding Sound Location

    Science.gov (United States)

    Ono, Munenori

    2014-01-01

    The localization of high-frequency sounds in the horizontal plane uses an interaural-level difference (ILD) cue, yet little is known about the synaptic mechanisms that underlie processing this cue in the inferior colliculus (IC) of mouse. Here, we study the synaptic currents that process ILD in vivo and use stimuli in which ILD varies around a constant average binaural level (ABL) to approximate sounds on the horizontal plane. Monaural stimulation in either ear produced EPSCs and IPSCs in most neurons. The temporal properties of monaural responses were well matched, suggesting connected functional zones with matched inputs. The EPSCs had three patterns in response to ABL stimuli, preference for the sound field with the highest level stimulus: (1) contralateral; (2) bilateral highly lateralized; or (3) at the center near 0 ILD. EPSCs and IPSCs were well correlated except in center-preferred neurons. Summation of the monaural EPSCs predicted the binaural excitatory response but less well than the summation of monaural IPSCs. Binaural EPSCs often showed a nonlinearity that strengthened the response to specific ILDs. Extracellular spike and intracellular current recordings from the same neuron showed that the ILD tuning of the spikes was sharper than that of the EPSCs. Thus, in the IC, balanced excitatory and inhibitory inputs may be a general feature of synaptic coding for many types of sound processing. PMID:24599475

  20. Altered excitatory-inhibitory balance in the NMDA-hypofunction model of schizophrenia

    Directory of Open Access Journals (Sweden)

    Colin Kehrer

    2008-04-01

    Full Text Available Schizophrenia is a common psychiatric disorder of high incidence, affecting approximately 1% of the world population. The essential neurotransmitter pathology of schizophrenia remains poorly defined, despite huge advances over the past half-century in identifying neurochemical and pathological abnormalities in the disease. The dopamine/serotonin hypothesis has originally provided much of the momentum for neurochemical research in schizophrenia. In recent years, the attention has, however, shifted to the glutamate system, the major excitatory neurotransmitter in the CNS and towards a concept of functional imbalance between excitatory and inhibitory transmission at the network level in various brain regions in schizophrenia. The evidence indicating a central role for the NMDAreceptor subtype in the etiology of schizophrenia has led to the NMDA-hypofunction model of this disease and the use of phencyclidines as a means to induce the NMDA-hypofunction state in animal models. The purpose of this review is to discuss recent findings highlighting the importance of the NMDA-hypofunction model of schizophrenia, both from a clinical perspective, as well as in opening a line of research, which enables electrophysiological studies at the cellular and network level in vitro. In particular, changes in excitation-inhibition (E/I balance in the NMDA-hypofunction model of the disease and the resulting changes in network behaviours, particularly in gamma frequency oscillatory activity, will be discussed.

  1. Aberrant development and plasticity of excitatory visual cortical networks in the absence of cpg15.

    Science.gov (United States)

    Picard, Nathalie; Leslie, Jennifer H; Trowbridge, Sara K; Subramanian, Jaichandar; Nedivi, Elly; Fagiolini, Michela

    2014-03-05

    During development, experience plays a crucial role in sculpting neuronal connections. Patterned neural activity guides formation of functional neural circuits through the selective stabilization of some synapses and the pruning of others. Activity-regulated factors are fundamental to this process, but their roles in synapse stabilization and maturation is still poorly understood. CPG15, encoded by the activity-regulated gene candidate plasticity gene 15, is a small, glycosylphosphatidylinositol (GPI)-linked, extracellular protein that promotes synapse stabilization. Here we show that global knock-out of cpg15 results in abnormal postnatal development of the excitatory network in visual cortex and an associated disruption in development of visual receptive field properties. In addition, whereas repeated stimulation induced potentiation and depression in wild-type mice, the depression was slower in cpg15 knock-out mice, suggesting impairment in short-term depression-like mechanisms. These findings establish the requirement for cpg15 in activity-dependent development of the visual system and demonstrate the importance of timely excitatory network development for normal visual function.

  2. Orexin-A modulates excitatory synaptic transmission and neuronal excitability in the spinal cord substantia gelatinosa.

    Science.gov (United States)

    Jeon, Younghoon; Park, Ki Bum; Pervin, Rokeya; Kim, Tae Wan; Youn, Dong-ho

    2015-09-14

    Although intrathecal orexin-A has been known to be antinociceptive in various pain models, the role of orexin-A in antinociception is not well characterized. In the present study, we examined whether orexin-A modulates primary afferent fiber-mediated or spontaneous excitatory synaptic transmission using transverse spinal cord slices with attached dorsal root. Bath-application of orexin-A (100nM) reduced the amplitude of excitatory postsynaptic currents (EPSCs) evoked by electrical stimulation of Aδ- or C-primary afferent fibers. The magnitude of reduction was much larger for EPSCs evoked by polysynaptic C-fibers than polysynaptic Aδ-fibers, whereas it was similar in EPSCs evoked by monosynaptic Aδ- or C-fibers. SB674042, an orexin-1 receptor antagonist, but not EMPA, an orexin-2 receptor antagonist, significantly inhibited the orexin-A-induced reduction in EPSC amplitude from mono- or polysynaptic Aδ-fibers, as well as from mono- or polysynaptic C-fibers. Furthermore, orexin-A significantly increased the frequency of spontaneous EPSCs but not the amplitude. This increase was almost completely blocked by both SB674042 and EMPA. On the other hand, orexin-A produced membrane oscillations and inward currents in the SG neurons that were partially or completely inhibited by SB674042 or EMPA, respectively. Thus, this study suggests that the spinal actions of orexin-A underlie orexin-A-induced antinociceptive effects via different subtypes of orexin receptors.

  3. Berkeley Supernova Ia Program I: Observations, Data Reduction, and Spectroscopic Sample of 582 Low-Redshift Type Ia Supernovae

    CERN Document Server

    Silverman, Jeffrey M; Filippenko, Alexei V; Ganeshalingam, Mohan; Barth, Aaron J; Chornock, Ryan; Griffith, Christopher V; Kong, Jason J; Lee, Nicholas; Leonard, Douglas C; Matheson, Thomas; Miller, Emily G; Steele, Thea N; Barris, Brian J; Bloom, Joshua S; Cobb, Bethany E; Coil, Alison L; Desroches, Louis-Benoit; Gates, Elinor L; Ho, Luis C; Jha, Saurabh W; Kandrashoff, Michael T; Li, Weidong; Mandel, Kaisey S; Modjaz, Maryam; Moore, Matthew R; Mostardi, Robin E; Papenkova, Marina S; Park, Sung; Perley, Daniel A; Poznanski, Dovi; Reuter, Cassie A; Scala, James; Serduke, Franklin J D; Shields, Joseph C; Swift, Brandon J; Tonry, John L; Van Dyk, Schuyler D; Wang, Xiaofeng; Wong, Diane S

    2012-01-01

    In this first paper in a series we present 1298 low-redshift (z < 0.2) optical spectra of 582 Type Ia supernovae (SNe Ia) observed from 1989 through 2008 as part of the Berkeley SN Ia Program (BSNIP). 584 spectra of 199 SNe Ia have well-calibrated light curves with measured distance moduli, and many of the spectra have been corrected for host-galaxy contamination. Most of the data were obtained using the Kast double spectrograph mounted on the Shane 3 m telescope at Lick Observatory and have a typical wavelength range of 3300-10,400 Ang., roughly twice as wide as spectra from most previously published datasets. We present our observing and reduction procedures, and we describe the resulting SN Database (SNDB), which will be an online, public, searchable database containing all of our fully reduced spectra and companion photometry. In addition, we discuss our spectral classification scheme (using the SuperNova IDentification code, SNID; Blondin & Tonry 2007), utilizing our newly constructed set of SNID ...

  4. The evidence for nitric oxide synthase immunopositivity in the monosynaptic Ia-motoneuron pathway of the dog.

    Science.gov (United States)

    Marsala, Jozef; Lukácová, Nadezda; Sulla, Igor; Wohlfahrt, Peter; Marsala, Martin

    2005-09-01

    In this study, nitric oxide synthase immunohistochemistry supported by nicotinamide adenine dinucleotide phosphate diaphorase histochemistry was used to demonstrate the nitric oxide synthase immunoreactivity in the monosynaptic Ia-motoneuron pathway exemplified by structural components of the afferent limb of the soleus H-reflex in the dog. A noticeable number of medium-sized intensely nitric oxide synthase immunoreactive somata (1000-2000 microm(2) square area) and large intraganglionic nitric oxide synthase immunoreactive fibers, presumed to be Ia axons, was found in the L7 and S1 dorsal root ganglia. The existence of nitric oxide synthase immunoreactive fibers (6-8 microm in diameter, not counting the myelin sheath) was confirmed in L7 and S1 dorsal roots and in the medial bundle of both dorsal roots before entering the dorsal root entry zone. By virtue of the funicular organization of nitric oxide synthase immunoreactive fibers in the dorsal funiculus, the largest nitric oxide synthase immunoreactive fibers represent stem Ia axons located in the deep portion of the dorsal funiculus close to the dorsomedial margin of the dorsal horn. Upon entering the gray matter of L7 and S1 segments and passing through the medial half of the dorsal horn, tapered nitric oxide synthase immunoreactive collaterals of the stem Ia fibers pass through the deep layers of the dorsal horn and intermediate zone, and terminate in the group of homonymous motoneurons in L7 and S1 segments innervating the gastrocnemius-soleus muscles. Terminal fibers issued in the ventral horn intensely nitric oxide synthase immunoreactive terminals with long axis ranging from 0.7 to >or=15.1 microm presumed to be Ia bNOS-IR boutons. This finding is unique in that it focuses directly on nitric oxide synthase immunopositivity in the signalling transmitted by proprioceptive Ia fibers. Nitric oxide synthase immunoreactive boutons were found in the neuropil of Clarke's column of L4 segment, varying greatly in

  5. Effect of topiramate on partial excitatory amino acids in hippocampal dentate gyrus of rats after alcohol withdrawal

    Institute of Scientific and Technical Information of China (English)

    Qinghua Yang; Guang Wu; Haiying Jiang; Yuanzhe Jin; Songbiao Cui

    2006-01-01

    BACKGROUND: Many researches have indicated that the imbalances of various amino acid transmitters and neurotransmitters in brain are involved in the formation of alcohol withdrawal, especially that glutamic acid is one of the important transmitters for alcohol tolerance in central nervous system.OBJECTIVE: To observe the changes of excitatory amino acids in hippocampal dentate gyrus in rats with long-term alcohol drinking after withdrawal under consciousness, and investigate the therapeutic effect of topiramate on alcohol withdrawal.DESIGN: A randomized control animal experiment.SETTING: Department of Neurology, Affiliated Hospital of Yanbian University.MATERIALS: Thirty male Wistar rats of 4 months old, weighing 300-350 g, were purchased from the Experimental Animal Department, Medical College of Yanbian University. Topiramate was produced by Swish Cilag Company, and the batch number was 02CS063.METHODS: The experiments were carried out in the Department of Physiology, Medical College of Yanbian University from August 2005 to February 2006. ① The rats were divided randomly into three groups: control group (n=10), alcohol group (n=10) and topiramate-treated group (n=10). Rats in the alcohol group and topiramate-treated group were given intragastric perfusion of 500 g/L alcohol (10 mL/kg), once a day for 4 weeks successively, and then those in the topiramate-treated group were treated with 80 mg/kg topiramate at 24 hours after the last perfusion of alcohol, once a day for 3 days successively. Rats in the control group were intragastricly given isovolume saline. ② The withdrawal symptoms were assessed at 6, 30, 48 and 72 hours after the last perfusion of alcohol by using the withdrawal rating scale set by Erden et al,which had four observational indexes of stereotyped behaviors, agitation, tail stiffness and abnormal posture,each index was scored by 5 points, the higher the score, the more obvious the symptoms. ③ The contents of aspartic acid and glutamic acid

  6. THE 1999aa-LIKE TYPE Ia SUPERNOVA IPTF14BDN IN THE ULTRAVIOLET AND OPTICAL

    Energy Technology Data Exchange (ETDEWEB)

    Smitka, Michael T.; Brown, Peter J.; Suntzeff, Nicholas B. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Zhang, Jujia; Zhai, Qian [Yunnan Observatories (YNAO), Chinese Academy of Sciences, Kunming 650011 (China); Wang, Xiaofeng; Mo, Jun [Physics Department and Tsinghua Center for Astrophysics (THCA), Tsinghua University, Beijing 100084 (China); Zhang, Tianmeng, E-mail: mikesmitka@gmail.com [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2015-11-01

    We present ultraviolet (UV) and optical photometry and spectra of the 1999aa-like supernova (SN) iPTF14bdn. The UV data were observed using the Swift Ultraviolet/Optical Telescope and constitute the first UV spectral series of a 1999aa-like SN. From the photometry, we measure Δm{sub 15}(B) = 0.84 ± 0.05 mag and blue UV colors at epochs earlier than −5 days. The spectra show that the early-time blue colors are the result of less absorption between 2800−3200 Å than is present in normal SNe Ia. Using model spectra fits of the data at −10 and +10 days, we identify the origin of this spectral feature to be a temperature effect in which doubly ionized iron group elements create an opacity “window.” We determine that the detection of high temperatures and large quantities of iron group elements at early epochs imply the mixing of a high Ni mass into the outer layers of the SN ejecta. We also identify the source of the I-band secondary maximum in iPTF14bdn to be the decay of Fe iii to Fe ii, as is seen in normal SNe Ia.

  7. ON THE RATES OF TYPE Ia SUPERNOVAE IN DWARF AND GIANT HOSTS WITH ROTSE-IIIb

    Energy Technology Data Exchange (ETDEWEB)

    Quimby, Robert M. [Kavli IPMU, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8583 (Japan); Yuan Fang [Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia); Akerlof, Carl [Physics Department, University of Michigan, Ann Arbor, MI 48109 (United States); Wheeler, J. Craig [Department of Astronomy, McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Warren, Michael S. [Theoretical Division, Mail Stop B227, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2012-12-01

    We present a sample of 23 spectroscopically confirmed Type Ia supernovae (SNe Ia) that were discovered in the background of galaxy clusters targeted by ROTSE-IIIb and use up to 18 of these to determine the local (z-bar 0.05) volumetric rate. Since our survey is flux limited and thus biased against fainter objects, the pseudo-absolute magnitude distribution (pAMD) of SNe Ia in a given volume is an important concern, especially the relative frequency of high- to low-luminosity SNe Ia. We find that the pAMD derived from the volume-limited Lick Observatory Supernova Search (LOSS) sample is incompatible with the distribution of SNe Ia in a volume-limited (z < 0.12) sub-sample of the Sloan Digital Sky Survey II (SDSS-II). The LOSS sample requires far more low-luminosity SNe Ia than the SDSS-II can accommodate. Even though LOSS and SDSS-II have sampled different SNe Ia populations, their volumetric rates are surprisingly similar. Using the same model pAMD adopted in the SDSS-II SNe Ia rate calculation and excluding two high-luminosity SNe Ia from our sample, we derive a rate that is marginally higher than previous low-redshift determinations. With our full sample and the LOSS pAMD, our rate is more than double the canonical value. We also find that 5 of our 18 SNe Ia are hosted by very low luminosity (M{sub B} > -16) galaxies, whereas only 1 out of 79 nearby SDSS-II SNe Ia have such faint hosts. It is possible that previous works have undercounted either low-luminosity SNe Ia, SNe Ia in low-luminosity hosts, or peculiar SNe Ia (sometimes explicitly), and the total SNe Ia rate may be higher than the canonical value.

  8. NR2 subunits and NMDA receptors on lamina II inhibitory and excitatory interneurons of the mouse dorsal horn

    Directory of Open Access Journals (Sweden)

    MacDermott Amy B

    2010-05-01

    Full Text Available Abstract Background NMDA receptors expressed by spinal cord neurons in the superficial dorsal horn are involved in the development of chronic pain associated with inflammation and nerve injury. The superficial dorsal horn has a complex and still poorly understood circuitry that is mainly populated by inhibitory and excitatory interneurons. Little is known about how NMDA receptor subunit composition, and therefore pharmacology and voltage dependence, varies with neuronal cell type. NMDA receptors are typically composed of two NR1 subunits and two of four NR2 subunits, NR2A-2D. We took advantage of the differences in Mg2+ sensitivity of the NMDA receptor subtypes together with subtype preferring antagonists to identify the NR2 subunit composition of NMDA receptors expressed on lamina II inhibitory and excitatory interneurons. To distinguish between excitatory and inhibitory interneurons, we used transgenic mice expressing enhanced green fluorescent protein driven by the GAD67 promoter. Results Analysis of conductance ratio and selective antagonists showed that lamina II GABAergic interneurons express both the NR2A/B containing Mg2+ sensitive receptors and the NR2C/D containing NMDA receptors with less Mg2+ sensitivity. In contrast, excitatory lamina II interneurons express primarily NR2A/B containing receptors. Despite this clear difference in NMDA receptor subunit expression in the two neuronal populations, focally stimulated synaptic input is mediated exclusively by NR2A and 2B containing receptors in both neuronal populations. Conclusions Stronger expression of NMDA receptors with NR2C/D subunits by inhibitory interneurons compared to excitatory interneurons may provide a mechanism to selectively increase activity of inhibitory neurons during intense excitatory drive that can provide inhibitory feedback.

  9. The effect of STDP temporal kernel structure on the learning dynamics of single excitatory and inhibitory synapses.

    Directory of Open Access Journals (Sweden)

    Yotam Luz

    Full Text Available Spike-Timing Dependent Plasticity (STDP is characterized by a wide range of temporal kernels. However, much of the theoretical work has focused on a specific kernel - the "temporally asymmetric Hebbian" learning rules. Previous studies linked excitatory STDP to positive feedback that can account for the emergence of response selectivity. Inhibitory plasticity was associated with negative feedback that can balance the excitatory and inhibitory inputs. Here we study the possible computational role of the temporal structure of the STDP. We represent the STDP as a superposition of two processes: potentiation and depression. This allows us to model a wide range of experimentally observed STDP kernels, from Hebbian to anti-Hebbian, by varying a single parameter. We investigate STDP dynamics of a single excitatory or inhibitory synapse in purely feed-forward architecture. We derive a mean-field-Fokker-Planck dynamics for the synaptic weight and analyze the effect of STDP structure on the fixed points of the mean field dynamics. We find a phase transition along the Hebbian to anti-Hebbian parameter from a phase that is characterized by a unimodal distribution of the synaptic weight, in which the STDP dynamics is governed by negative feedback, to a phase with positive feedback characterized by a bimodal distribution. The critical point of this transition depends on general properties of the STDP dynamics and not on the fine details. Namely, the dynamics is affected by the pre-post correlations only via a single number that quantifies its overlap with the STDP kernel. We find that by manipulating the STDP temporal kernel, negative feedback can be induced in excitatory synapses and positive feedback in inhibitory. Moreover, there is an exact symmetry between inhibitory and excitatory plasticity, i.e., for every STDP rule of inhibitory synapse there exists an STDP rule for excitatory synapse, such that their dynamics is identical.

  10. Hubble Space Telescope spectra of the type Ia supernova SN 2011fe: A low-energy delayed detonation of a white dwarf with Z

    CERN Document Server

    Mazzali, Paolo; Hachinger, Stephan; Ellis, Richard; Nugent, Peter E; Howell, D Andrew; Gal-Yam, Avishay; Maguire, Kate; Cooke, Jeff; Thomas, Rollin

    2013-01-01

    Hubble Space Telescope spectroscopic observations of the nearby type Ia supernova (SN Ia) SN 2011fe, taken on 10 epochs from -13.5 to +41 days relative to B-band maximum light, and spanning the far-ultraviolet (UV) to the near-infrared (IR) are presented. This spectroscopic coverage makes SN 2011fe the best-studied local SN Ia to date. SN 2011fe is a typical moderately-luminous SN Ia with no evidence for dust extinction. Its near-UV spectral properties are representative of a larger sample of local events studied in Maguire et al. (2012). As a result, conclusions inferred from our detailed investigations are likely representative of those for other normal SNe Ia. The near-UV to optical spectra of SN 2011fe are modelled with a Monte Carlo radiative transfer code using the technique of 'abundance tomography', providing tight constraints on the density structure and abundance stratification of the event. SN 2011fe was a relatively weak explosion, with moderate Fe-group yields. Although its density structure is c...

  11. No Contribution of GAD-65 and IA-2 Autoantibodies around Time of Diagnosis to the Increasing Incidence of Juvenile Type 1 Diabetes: A 9-Year Nationwide Danish Study

    Directory of Open Access Journals (Sweden)

    Steffen U. Thorsen

    2016-01-01

    Full Text Available Aims. A new perspective on autoantibodies as pivotal players in the pathogenesis of type 1 diabetes (T1D has recently emerged. Our key objective was to examine whether increased levels of autoantibodies against the β-cell autoantigens glutamic acid decarboxylase (isoform 65 (GADA and insulinoma associated antigen-2A (IA-2A mirrored the 3.4% annual increase in incidence of T1D. Methods. From the Danish Childhood Diabetes Register, we randomly selected 500 patients and 500 siblings for GADA and IA-2A analysis (1997 through 2005. Blood samples were taken within three months after onset. A robust log-normal regression model was used. Nine hundred children and adolescents had complete records and were included in the analysis. Cochran-Armitage test for trend was used to evaluate changes in prevalence of autoantibody positivity by period. Results. No significant changes in levels of GADA and IA-2A were found over our 9-year study period. No trends in autoantibody positivity—in either patients or siblings—were found. Levels of GADA and IA-2A were significantly associated with HLA risk groups and GADA with age. Conclusion. The prevalence of positivity and the levels of GADA and IA-2A have not changed between 1997 and 2005 in newly diagnosed patients with T1D and their siblings without T1D.

  12. Optical Light Curve of the Type Ia Supernova 1998bu in M96 and the Supernova Calibration of the Hubble Constant

    CERN Document Server

    Suntzeff, N B; Covarrubias, R; Navarrete, M; Pérez, J J; Guerra, A I; Acevedo, M T; Doyle, L R; Harrison, T; Kane, S; Long, K S; Maza, J; Miller, S; Piatti, A E; Claria, J J; Ahumada, A V; Pritzl, B J; Winkler, P F; Suntzeff, Nicholas B.; Doyle, Laurance R.; Harrison, Thomas; Kane, Stephen; Long, Knox S.; Maza, Jose; Miller, Scott; Piatti, Andres E.; Claria, Juan J.; Ahumada, Andrea V.; Pritzl, Barton

    1998-01-01

    We present the UBVRI light curves of the Type Ia supernova SN 1998bu which appeared in the nearby galaxy M96 (NGC 3368). M96 is a spiral galaxy in the Leo I group which has a Cepheid-based distance. Our photometry allows us to calculate the absolute magnitude and reddening of this supernova. These data, when combined with measurements of the four other well-observed supernovae with Cepheid based distances, allow us to calculate the Hubble constant with respect to the Hubble flow defined by the distant Calan/Tololo Type Ia sample. We find a Hubble constant of 64.0 +/- 2.2(internal) +/- 3.5(external) km/s/Mpc, consistent with most previous estimates based on Type Ia supernovae. We note that the two well-observed Type Ia supernovae in Fornax, if placed at the Cepheid distance to the possible Fornax spiral NGC 1365, are apparently too faint with respect to the Calan/Tololo sample calibrated with the five Type Ia supernovae with Cepheid distances to the host galaxies.

  13. Prenatal Ethanol Exposure Persistently Alters Endocannabinoid Signaling and Endocannabinoid-Mediated Excitatory Synaptic Plasticity in Ventral Tegmental Area Dopamine Neurons.

    Science.gov (United States)

    Hausknecht, Kathryn; Shen, Ying-Ling; Wang, Rui-Xiang; Haj-Dahmane, Samir; Shen, Roh-Yu

    2017-06-14

    Prenatal ethanol exposure (PE) leads to increased addiction risk which could be mediated by enhanced excitatory synaptic strength in ventral tegmental area (VTA) dopamine (DA) neurons. Previous studies have shown that PE enhances excitatory synaptic strength by facilitating an anti-Hebbian form of long-term potentiation (LTP). In this study, we investigated the effect of PE on endocannabinoid-mediated long-term depression (eCB-LTD) in VTA DA neurons. Rats were exposed to moderate (3 g/kg/d) or high (6 g/kg/d) levels of ethanol during gestation. Whole-cell recordings were conducted in male offspring between 4 and 10 weeks old.We found that PE led to increased amphetamine self-administration. Both moderate and high levels of PE persistently reduced low-frequency stimulation-induced eCB-LTD. Furthermore, action potential-independent glutamate release was regulated by tonic eCB signaling in PE animals. Mechanistic studies for impaired eCB-LTD revealed that PE downregulated CB1 receptor function. Interestingly, eCB-LTD in PE animals was rescued by metabotropic glutamate receptor I activation, suggesting that PE did not impair the synthesis/release of eCBs. In contrast, eCB-LTD in PE animals was not rescued by increasing presynaptic activity, which actually led to LTP in PE animals, whereas LTD was still observed in controls. This result shows that the regulation of excitatory synaptic plasticity is fundamentally altered in PE animals. Together, PE leads to impaired eCB-LTD at the excitatory synapses of VTA DA neurons primarily due to CB1 receptor downregulation. This effect could contribute to enhanced LTP and the maintenance of augmented excitatory synaptic strength in VTA DA neurons and increased addiction risk after PE.SIGNIFICANCE STATEMENT Prenatal ethanol exposure (PE) is among many adverse developmental factors known to increase drug addiction risk. Increased excitatory synaptic strength in VTA DA neurons is a critical cellular mechanism for addiction risk. Our

  14. Development of Adult-Generated Cell Connectivity with Excitatory and Inhibitory Cell Populations in the Hippocampus.

    Science.gov (United States)

    Restivo, Leonardo; Niibori, Yosuke; Mercaldo, Valentina; Josselyn, Sheena A; Frankland, Paul W

    2015-07-22

    New neurons are generated continuously in the subgranular zone of the hippocampus and integrate into existing hippocampal circuits throughout adulthood. Although the addition of these new neurons may facilitate the formation of new memories, as they integrate, they provide additional excitatory drive to CA3 pyramidal neurons. During development, to maintain homeostasis, new neurons form preferential contacts with local inhibitory circuits. Using retroviral and transgenic approaches to label adult-generated granule cells, we first asked whether a comparable process occurs in the adult hippocampus in mice. Similar to development, we found that, during adulthood, new neurons form connections with inhibitory cells in the dentate gyrus, hilus, and CA3 regions as they integrate into hippocampal circuits. In particular, en passant bouton and filopodia connections with CA3 interneurons peak when adult-generated dentate granule cells (DGCs) are ∼4 weeks of age, a time point when these cells are most excitable. Consistent with this, optical stimulation of 4-week-old (but not 6- or 8-week-old) adult-generated DGCs strongly activated CA3 interneurons. Finally, we found that CA3 interneurons were activated robustly during learning and that their activity was strongly coupled with activity of 4-week-old (but not older) adult-generated DGCs. These data indicate that, as adult-generated neurons integrate into hippocampal circuits, they transiently form strong anatomical, effective, and functional connections with local inhibitory circuits in CA3. Significance statement: New neurons are generated continuously in the subgranular zone of the hippocampus and integrate into existing hippocampal circuits throughout adulthood. Understanding how these cells integrate within well formed circuits will increase our knowledge about the basic principles governing circuit assembly in the adult hippocampus. This study uses a combined connectivity analysis (anatomical, functional, and effective

  15. Excitatory Hindbrain-Forebrain Communication Is Required for Cisplatin-Induced Anorexia and Weight Loss.

    Science.gov (United States)

    Alhadeff, Amber L; Holland, Ruby A; Zheng, Huiyuan; Rinaman, Linda; Grill, Harvey J; De Jonghe, Bart C

    2017-01-11

    Cisplatin chemotherapy is commonly used to treat cancer despite severe energy balance side effects. In rats, cisplatin activates nucleus tractus solitarius (NTS) projections to the lateral parabrachial nucleus (lPBN) and calcitonin-gene related peptide (CGRP) projections from the lPBN to the central nucleus of the amygdala (CeA). We demonstrated previously that CeA glutamate receptor signaling mediates cisplatin-induced anorexia and body weight loss. Here, we used neuroanatomical tracing, immunofluorescence, and confocal imaging to demonstrate that virtually all NTS→lPBN and lPBN→CeA CGRP projections coexpress vesicular glutamate transporter 2 (VGLUT2), providing evidence that excitatory projections mediate cisplatin-induced energy balance dysregulation. To test whether lPBN→CeA projection neurons are required for cisplatin-induced anorexia and weight loss, we inhibited these neurons chemogenetically using a retrograde Cre-recombinase-expressing canine adenovirus-2 in combination with Cre-dependent inhibitory Designer Receptors Exclusive Activated by Designer Drugs (DREADDs) before cisplatin treatment. Inhibition of lPBN→CeA neurons attenuated cisplatin-induced anorexia and body weight loss significantly. Using a similar approach, we additionally demonstrated that inhibition of NTS→lPBN neurons attenuated cisplatin-induced anorexia and body weight loss significantly. Together, our data support the view that excitatory hindbrain-forebrain projections are necessary for cisplatin's untoward effects on energy intake, elucidating a key neuroanatomical circuit driving pathological anorexia and weight loss that accompanies chemotherapy treatment. Chemotherapy treatments are commonly used to treat cancers despite accompanying anorexia and weight loss that may limit treatment adherence and reduce patient quality of life. Strikingly, we lack a neural understanding of, and effective treatments for, chemotherapy-induced anorexia and weight loss. The current data

  16. Excitatory synaptic inputs on myenteric Dogiel type II neurones of the pig ileum.

    Science.gov (United States)

    Cornelissen, W; de Laet, A; Kroese, A B; van Bogaert, P P; Scheuermann, D W; Timmermans, J P

    2001-04-01

    The synaptic input on myenteric Dogiel type II neurones (n = 63) obtained from the ileum of 17 pigs was studied by intracellular recording. In 77% of the neurones, electrical stimulation of a fibre tract evoked fast excitatory postsynaptic potentials (fEPSPs) with an amplitude of 6 +/- 5 mV (mean +/- S.D.) and lasting 49 +/- 29 ms. The nicotinic nature of the fEPSPs was demonstrated by superfusing hexamethonium (20 microM). High-frequency stimulation (up to 20 Hz, 3 seconds) did not result in a rundown of the fEPSPs, and did not evoke slow excitatory or inhibitory postsynaptic potentials. The effects of neurotransmitters, possibly involved in these excitatory responses, were investigated. Pressure microejection of acetylcholine (10 mM in pipette) resulted in a fast nicotinic depolarisation in 67%(18/27) of the neurones (13 +/- 9 mV, duration 7.0 +/- 7.2 seconds) as did 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) application (10 mM; 14 +/- 10 mV, duration 4.1 +/- 2.8 seconds) in 76% of the cells. The fast nicotinic response to acetylcholine was sometimes (6/27) followed by a slow muscarinic depolarisation (8 +/- 4 mV; duration 38.7 +/- 10.8 seconds). Immunostaining revealed 5-hydroxytryptamine hydrochloride (5-HT)- and calcitonin gene-related peptide (CGRP)-positive neuronal baskets distributed around and in close vicinity to Dogiel type II neuronal cell bodies. Microejection of 5-HT (10 mM) resulted in a fast nicotinic-like depolarisation (12 +/- 6 mV, duration 3.0 +/- 1.3 seconds) in 4 of 8 neurones tested, whereas microejection of CGRP (20 mM) gave rise to a slow muscarinic-like depolarisation (6 +/- 2 mV, duration 56.0 +/- 27.5 seconds) in 8 of 12 neurones tested. In conclusion, myenteric Dogiel type II neurones in the porcine ileum receive diverse synaptic input. Mainly with regard to the prominent presence of nicotinic responses, these neurones behave contrary to their guinea pig counterparts.

  17. Quark-Novae Ia in the Hubble diagram: implications for dark energy

    Science.gov (United States)

    Ouyed, Rachid; Koning, Nico; Leahy, Denis; Staff, Jan E.; Cassidy, Daniel T.

    2014-05-01

    The accelerated expansion of the Universe was proposed through the use of Type-Ia supernovae (SNe) as standard candles. The standardization depends on an empirical correlation between the stretch/color and peak luminosity of the light curves. The use of Type-Ia SNe as standard candles rests on the assumption that their properties (and this correlation) do not vary with redshift. We consider the possibility that the majority of Type-Ia SNe are in fact caused by a Quark-Nova detonation in a tight neutron-star-CO-white-dwarf binary system, which forms a Quark-Nova Ia (QN-Ia). The spin-down energy injected by the Quark-Nova remnant (the quark star) contributes to the post-peak light curve and neatly explains the observed correlation between peak luminosity and light curve shape. We demonstrate that the parameters describing QN-Ia are NOT constant in redshift. Simulated QN-Ia light curves provide a test of the stretch/color correlation by comparing the true distance modulus with that determined using SN light curve fitters. We determine a correction between the true and fitted distance moduli, which when applied to Type-Ia SNe in the Hubble diagram recovers the ΩM = 1 cosmology. We conclude that Type-Ia SNe observations do not necessitate the need for an accelerating expansion of the Universe (if the observed SNe Ia are dominated by QNe Ia) and by association the need for dark energy.

  18. The core-degenerate scenario for the progenitors of type Ia supernovae

    CERN Document Server

    Wang, Bo; Zuo, Zhaoyu; Li, Yinbi; Luo, Xia; Zhang, Jujia; Liu, Dongdong; Wu, Chengyuan

    2016-01-01

    The origin of the progenitors of type Ia supernovae (SNe Ia) is still uncertain. The core-degenerate (CD) scenario has been proposed as an alternative way for the production of SNe Ia. In this scenario, SNe Ia are formed at the final stage of common-envelope evolution from a merger of a carbon-oxygen white dwarf (CO WD) with the CO core of an asymptotic giant branch companion. However, the birthrates of SNe Ia from this scenario are still not well determined. In this work, we performed a detailed investigation on the CD scenario based on a binary population synthesis approach. The SN Ia delay times from this scenario are basically in the range of 90Myr-2500Myr, mainly contributing to the observed SNe Ia with short and intermediate delay times although this scenario can also produce some old SNe Ia. Meanwhile, our work indicates that the Galactic birthrates of SNe Ia from this scenario are no more than 20% of total SNe Ia due to more careful treatment of mass transfer. Although the SN Ia birthrates in the pres...

  19. Type Ia supernova diversity in three-dimensional delayed detonation models from variations in the central white dwarf density at ignition

    CERN Document Server

    Seitenzahl, I R; Roepke, F K

    2010-01-01

    Delayed detonations of Chandrasekhar-mass white dwarfs (WDs) have been very successful in explaining the spectra, light curves, and the width-luminosity relation of spectroscopically normal Type Ia supernovae (SNe Ia). The ignition of the thermonuclear deflagration flame at the end of the convective carbon "simmering" phase in the core of the WD is still not well understood and much about the ignition kernel distribution remains unknown. Furthermore, the central density at the time of ignition depends on the still uncertain screened carbon fusion reaction rates, the accretion history and cooling time of the progenitor, and the composition. We present the results of twelve high-resolution three-dimensional delayed detonation SN Ia explosion simulations that employ a new criterion to trigger the deflagration to detonation transition (DDT). All simulations trigger our DDT criterion and the resulting delayed detonations unbind the star. We find a trend of increasing iron group element (IGE) production with increa...

  20. 12th International Conference on Intelligent Autonomous Systems (IAS-12)

    CERN Document Server

    Yoon, Kwang-Joon; Lee, Jangmyung; Frontiers of Intelligent Autonomous Systems

    2013-01-01

    This carefully edited volume aims at providing readers with the most recent progress on intelligent autonomous systems, with its particular emphasis on intelligent autonomous ground, aerial and underwater vehicles as well as service robots for home and healthcare under the context of the aforementioned convergence. “Frontiers of Intelligent Autonomous Systems” includes thoroughly revised and extended papers selected from the 12th International Conference on Intelligent Autonomous Systems (IAS-12), held in Jeju, Korea, June 26-29, 2012. The editors chose 35 papers out of the 202 papers presented at IAS-12 which are organized into three chapters: Chapter 1 is dedicated to autonomous navigation and mobile manipulation, Chapter 2 to unmanned aerial and underwater vehicles and Chapter 3 to service robots for home and healthcare. To help the readers to easily access this volume, each chapter starts with a chapter summary introduced by one of the editors: Chapter 1 by Sukhan Lee, Chapter 2 by Kwang Joon Yoon and...

  1. Dynamics of the Remnant of Kepler's Type Ia Supernova

    Science.gov (United States)

    Borkowski, Kazimierz

    2013-09-01

    The remnant of Kepler's Type Ia SN shows an interaction of SN ejecta with a highly asymmetric ambient circumstellar medium (CSM). This material was ejected by a single-degenerate progenitor prior to the explosion, and its complex spatial distribution contains invaluable information about the progenitor itself. We propose a third-epoch observation of Kepler's SNR that will provide us with much improved expansion rates, allowing for measurements of shock speeds along the whole periphery of the remnant. These measurements will be compared with 3-D hydrodynamic simulations, thus unraveling the true shape of the CSM in a Type Ia progenitor. They will also advance our knowledge of poorly-understood particle acceleration and magnetic field amplification processes in fast SNR shocks.

  2. Prospective Type Ia Supernova Surveys From Dome A

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A.; /LBL, Berkeley; Bonissent, A.; /Marseille, CPPM; Christiansen, J.L.; /Cal. Poly.; Ealet, A.; /Marseille, CPPM; Faccioli, L.; /UC, Berkeley; Gladney, L.; /Pennsylvania U.; Kushner, G.; /LBL, Berkeley; Linder, E.; /UC, Berkeley; Stoughton, C.; /Fermilab; Wang, L.; /Texas A-M /Purple Mountain Observ.

    2010-02-01

    Dome A, the highest plateau in Antarctica, is being developed as a site for an astronomical observatory. The planned telescopes and instrumentation and the unique site characteristics are conducive toward Type Ia supernova surveys for cosmology. A self-contained search and survey over five years can yield a spectro-photometric time series of {approx}1000 z < 0.08 supernovae. These can serve to anchor the Hubble diagram and quantify the relationship between luminosities and heterogeneities within the Type Ia supernova class, reducing systematics. Larger aperture ({approx}>4-m) telescopes are capable of discovering supernovae shortly after explosion out to z {approx} 3. These can be fed to space telescopes, and can isolate systematics and extend the redshift range over which we measure the expansion history of the universe.

  3. Prospective Type Ia supernova surveys from Dome A

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A.; Bonissent, A.; Christiansen, J. L.; Ealet, A.; Faccioli, L.; Gladney, L.; Kushner, G.; Linder, E.; Stoughton, C.; Wang, L.

    2010-03-10

    Dome A, the highest plateau in Antarctica, is being developed as a site for an astronomical observatory. The planned telescopes and instrumentation and the unique site characteristics are conducive toward Type Ia supernova surveys for cosmology. A self-contained search and survey over 5 years can yield a spectro-photometric time series of ~;; 1000 z< 0:08 supernovae. These can serve to anchor the Hubble diagram and quantify the relationship between luminosities and heterogeneities within the Type Ia supernova class, reducing systematics. Larger aperture (>=4-m) telescopes are capable of discovering supernovae shortly after explosion out to z ~;; 3. These can be fed to space telescopes, and can isolate systematics and extend the redshift range over which we measure the expansion history of the universe.

  4. Publication of the accounting policies in accordance with IAS 8

    Directory of Open Access Journals (Sweden)

    Bešlić Ivana

    2013-01-01

    Full Text Available In global economy, accounting policies respectively the notes to financial statements of the enterprise are used as a complement for good quality financial reporting and strategic management. Selected accounting policies aligned with IAS/IFRS, as a key element of the notes complement content of accounting information in financial statements: balance sheet, income statement, cash flow statement, statement of changes on capital. This paper focuses on: 1. accounting principles and standards as well as origination in accounting policies, 2. choice of accounting policies in the area of long-term assets and inventory, 3. important features of notes to financial statements. In the Republic of Serbia publication of accounting policies must be in accordance with IAS 8. In this paper the autors used following methods of research: an overview relevant literature, the method of analysis, the method of synthesis, the method of induction, method of deduction and mathematical method.

  5. Photometric redshifts for supernovae Ia in the Supernova Legacy Survey

    CERN Document Server

    Palanque-Delabrouille, Nathalie; Pascal, S; Rich, J; Guy, J; Bazin, G; Astier, P; Balland, C; Basa, S; Carlberg, R G; Conley, A; Fouchez, D; Hardin, D; Hook, I M; Howell, D A; Pain, R; Perrett, K; Pritchet, C J; Regnault, N; Sullivan, M

    2009-01-01

    We present a method using the SALT2 light curve fitter to determine the redshift of Type Ia supernovae in the Supernova Legacy Survey (SNLS) based on their photometry in g', r', i' and z'. On 289 supernovae of the first three years of SNLS data, we obtain a precision $\\sigma_{\\Delta z/(1+z)} = 0.022$ on average up to a redshift of 1.0, with a higher precision of 0.016 for z0.45. The rate of events with $|\\Delta z|/(1+z)>0.15$ (catastrophic errors) is 1.4%. Both the precision and the rate of catastrophic errors are better than what can be currently obtained using host galaxy photometric redshifts. Photometric redshifts of this precision may be useful for future experiments which aim to discover up to millions of supernovae Ia but without spectroscopy for most of them.

  6. Type Ia supernova rate at $z \\sim 0.1$

    CERN Document Server

    Hardin, D P; Alard, C; Albert, J N; Amadon, A; Andersen, J; Ansari, R; Aubourg, E; Bareyre, P; Bauer, F; Beaulieu, J P; Blanc, G; Bouquet, A; Char, S; Charlot, X; Couchot, F; Coutures, C; Derue, F; Ferlet, R; Glicenstein, J F; Goldman, B; Gould, A; Graff, D; Gros, M H; Haïssinski, J; Hamilton, J C; Kat, J; Kim, A; Lasserre, T; Lesquoy, E; Loup, C; Magneville, C; Mansoux, B; Marquette, J B; Maurice, E; Milshtein, A I; Moniez, M; Palanque-Delabrouille, Nathalie; Perdereau, O; Prévôt, L; Regnault, N; Rich, J; Spiro, Michel; Vidal-Madjar, A; Vigroux, L; Zylberajch, S

    2000-01-01

    We present the EROS nearby supernova ($z \\sim 0.02 - 0.2$) search and the analysis of the first year of data (1997). A total of 80 square degrees were surveyed. Eight supernov{\\ae} were detected, four of which were spectroscopically identified as type Ia supernov{\\ae}. The search efficiency was determined with a Monte-Carlo simulation taking into account the efficiencies for both supernova detection and host galaxy identification. Assuming that for a given galaxy the supernova rate is proportional to the galactic luminosity, we compute a type Ia supernova explosion rate of: ${\\cal R} = 0.44 {}_{-0.21}^{+0.35} {}_{-0.07}^{+0.13} h^2: / 10^{10} \\lbsun / 100 {\\rm yrs}$ at an average redshift of $\\sim 0.1$ where the errors are respectively statistical and systematic (type misidentification included).

  7. A Model for Forecasting Enlisted Student IA Billet Requirements

    Science.gov (United States)

    2016-03-01

    were promised and had at least one course failure . Training times Student execution depends on TTT. TTT includes under-instruction (UI) time and...Cleared for Public Release A Model for Forecasting Enlisted Student IA Billet Requirements Steven W. Belcher with David L. Reese...and Kletus S. Lawler March 2016 Copyright © 2016 CNA This document contains the best opinion of CNA at the time of issue. It does

  8. SURF IA Conflict Detection and Resolution Algorithm Evaluation

    Science.gov (United States)

    Jones, Denise R.; Chartrand, Ryan C.; Wilson, Sara R.; Commo, Sean A.; Barker, Glover D.

    2012-01-01

    The Enhanced Traffic Situational Awareness on the Airport Surface with Indications and Alerts (SURF IA) algorithm was evaluated in a fast-time batch simulation study at the National Aeronautics and Space Administration (NASA) Langley Research Center. SURF IA is designed to increase flight crew situation awareness of the runway environment and facilitate an appropriate and timely response to potential conflict situations. The purpose of the study was to evaluate the performance of the SURF IA algorithm under various runway scenarios, multiple levels of conflict detection and resolution (CD&R) system equipage, and various levels of horizontal position accuracy. This paper gives an overview of the SURF IA concept, simulation study, and results. Runway incursions are a serious aviation safety hazard. As such, the FAA is committed to reducing the severity, number, and rate of runway incursions by implementing a combination of guidance, education, outreach, training, technology, infrastructure, and risk identification and mitigation initiatives [1]. Progress has been made in reducing the number of serious incursions - from a high of 67 in Fiscal Year (FY) 2000 to 6 in FY2010. However, the rate of all incursions has risen steadily over recent years - from a rate of 12.3 incursions per million operations in FY2005 to a rate of 18.9 incursions per million operations in FY2010 [1, 2]. The National Transportation Safety Board (NTSB) also considers runway incursions to be a serious aviation safety hazard, listing runway incursion prevention as one of their most wanted transportation safety improvements [3]. The NTSB recommends that immediate warning of probable collisions/incursions be given directly to flight crews in the cockpit [4].

  9. IAS 1 Presentation of Financial Statements - A Closer Look

    OpenAIRE

    Muthupandian, K S

    2008-01-01

    The International Accounting Standards Committee issued the International Accounting Standard 1 Presentation of Financial Statements. The objective of IAS 1 is to prescribe the basis for presentation of general purpose financial statements (GPFS), to ensure comparability both with the entity's financial statements of previous periods and with the financial statements of other entities. The objective of GPFS is to provide information about the financial position, financial performance, and cas...

  10. IAS 7, Statement of Cash Flows – A Closer Look

    OpenAIRE

    Muthupandian, K S

    2008-01-01

    The International Accounting Standards Committee issued the the International Accounting Standard 7, Cash Flow Statements. The objective of IAS 7 is to require the presentation or provision of information about the historical changes in cash and cash equivalents of an enterprise by means of a statement of cash flows, which classifies cash flows during the period according to operating, investing, and financing activities. This article presents a closer look of standard (objective, scope, defi...

  11. The Absolute Magnitudes of Type Ia Supernovae in the Ultraviolet

    Science.gov (United States)

    Brown, Peter J.; Roming, Peter W. A.; Milne, Peter; Bufano, Filomena; Ciardullo, Robin; Elias-Rosa, Nancy; Filippenko, Alexei V.; Foley, Ryan J.; Gehrels, Neil; Gronwall, Caryl; Hicken, Malcolm; Holland, Stephen T.; Hoversten, Erik A.; Immler, Stefan; Kirshner, Robert P.; Li, Weidong; Mazzali, Paolo; Phillips, Mark M.; Pritchard, Tyler; Still, Martin; Turatto, Massimo; Vanden Berk, Daniel

    2010-10-01

    We examine the absolute magnitudes and light-curve shapes of 14 nearby (redshift z = 0.004-0.027) Type Ia supernovae (SNe Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1 rc covering ~2600-3300 Å after removing optical light, and u ≈ 3000-4000 Å) compared to a mid-UV filter (uvm2 ≈2000-2400 Å). The uvw1 rc - b colors show a scatter of ~0.3 mag while uvm2-b scatters by nearly 0.9 mag. Similarly, while the scatter in colors between neighboring filters is small in the optical and somewhat larger in the near-UV, the large scatter in the uvm2 - uvw1 colors implies significantly larger spectral variability below 2600 Å. We find that in the near-UV the absolute magnitudes at peak brightness of normal SNe Ia in our sample are correlated with the optical decay rate with a scatter of 0.4 mag, comparable to that found for the optical in our sample. However, in the mid-UV the scatter is larger, ~1 mag, possibly indicating differences in metallicity. We find no strong correlation between either the UV light-curve shapes or the UV colors and the UV absolute magnitudes. With larger samples, the UV luminosity might be useful as an additional constraint to help determine distance, extinction, and metallicity in order to improve the utility of SNe Ia as standardized candles.

  12. Universal Robots公司首次亮相 IAS

    Institute of Scientific and Technical Information of China (English)

    李剑琦

    2012-01-01

    在中国国际工业博览会(IAS2012)上,丹麦创新工业机器人制造商Universal Robots公司携旗下创新、轻型、灵活的UR5型机器人首次亮相,为蓬勃发展的中国工业机器人市场注入新鲜活力。

  13. The type Ia supernovae and the Hubble's constant

    OpenAIRE

    2004-01-01

    The Hubble's constant is usually surmised to be a constant; but the experiments show a large spread and conflicting estimates. According to the plasma-redshift theory, the Hubble's constant varies with the plasma densities along the line of sight. It varies then slightly with the direction and the distance to a supernova and a galaxy. The relation between the magnitudes of type Ia supernovae and their observed redshifts results in an Hubble's constant with an average value in intergalactic sp...

  14. Armas y letras (notas sobre Menudencia [Tutaméia

    Directory of Open Access Journals (Sweden)

    Danielle Corpas

    2014-07-01

    Full Text Available En la prosa creativa del último libro de Guimarães Rosa, Menudencia [Tutaméia] (1967, aparecen imbricadas consignas de la modernización y so-ciabilización moldeadas por un pasado esclavista. Este artículo se centra en las narraciones de Menudencia, que muestran las relaciones entre, por una parte, anomia y costumbres patriarcales y, por otra, recursos, mentalidad y estética, que aparentemente los confrontan.

  15. The Absolute Magnitudes of Type Ia Supernovae in the Ultraviolet

    CERN Document Server

    Brown, Peter J; Milne, Peter; Bufano, Filomena; Ciardullo, Robin; Elias-Rosa, Nancy; Filippenko, Alexei V; Foley, Ryan J; Gehrels, Neil; Gronwall, Caryl; Hicken, Malcolm; Holland, Stephen T; Hoversten, Erik A; Immler, Stefan; Kirshner, Robert P; Li, Weidong; Mazzali, Paolo; Phillips, Mark M; Pritchard, Tyler; Still, Martin; Turatto, Massimo; Berk, Daniel Vanden

    2010-01-01

    We examine the absolute magnitudes and light-curve shapes of 14 nearby(redshift z = 0.004--0.027) Type Ia supernovae (SNe~Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way (MW) extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1_rc covering ~2600-3300 A after removing optical light, and u ~3000--4000 A) compared to a mid-UV filter (uvm2 ~2000-2400 A). The uvw1_rc-b colors show a scatter of ~0.3 mag while uvm2-b scatters by nearly 0.9 mag. Similarly, while the scatter in colors between neighboring filters is small in the optical and somewhat larger in the near-UV, the large scatter in the uvm2-uvw1 colors implies significantly larger spectral variability below 2600 A. We find that in the near-UV the absolute magnitudes at peak brightness of normal SNe Ia in our sample are correlated with ...

  16. Hydrogen and helium in the spectra of Type Ia supernovae

    CERN Document Server

    Lundqvist, Peter; Sollerman, Jesper; Kozma, Cecilia; Baron, E; Cox, Nick L J; Fransson, Claes; Leibundgut, Bruno; Spyromilio, Jason

    2013-01-01

    We present predictions for hydrogen and helium emission line luminosities from circumstellar matter around Type Ia supernovae (SNe Ia) using time dependent photoionization modeling. ESO/VLT optical echelle spectra of the SN Ia 2000cx were taken before and up to 70 days after maximum. We detect no hydrogen and helium lines, and place an upper limit on the mass loss rate for the putative wind of less than 1.3EE{-5} solar masses per year, assuming a speed of 10 km/s and solar abundances for the wind. In a helium-enriched case, the best line to constrain the mass loss would be He I 10,830 A. We confirm the details of interstellar Na I and Ca II absorption towards SN 2000cx as discussed by Patat et al., but also find evidence for 6613.56 A Diffuse Interstellar Band (DIB) absorption in the Milky Way. We discuss measurements of the X-ray emission from the interaction between the supernova ejecta and the wind and we re-evaluate observations of SN 1992A obtained 16 days after maximum by Schlegel & Petre. We find a...

  17. Anomalous extinction behaviour towards the Type Ia SN 2003cg

    CERN Document Server

    Elias-Rosa, N; Benetti, S; Cappellaro, E; Harutyunyan, A; Hillebrandt, W; Kotak, R; Mazzali, P A; Meikle, W P S; Navasardyan, H; Pastorello, A; Patat, F; Pignata, G; Qiu, Y; Salvo, M E; Stehle, M; Turatto, M

    2006-01-01

    We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 2003cg, which exploded in the nearby galaxy NGC 3169. The observations cover a period between -8.5 and +414 days post-maximum. SN 2003cg is a normal but highly-reddened Type Ia event. Its B magnitude at maximum B_max = 15.94+/-0.04 and Delta m_15(B)_obs = 1.12+/-0.04 (Delta m_15(B)_intrinsic = 1.25+/-0.05). Allowing R_v to become a free parameter within the Cardelli et al. (1989) extinction law, simultaneous matches to a range of colour curves of normal SNe Ia yielded E(B-V) = 1.33+/-0.11, and R_v = 1.80+/-0.19. While the value obtained for R_v is small, such values have been invoked in the past, and may imply a grain size which is small compared with the average value for the local ISM.

  18. Formation of Dust in the Ejecta of Type Ia Supernovae

    CERN Document Server

    Nozawa, Takaya; Kozasa, Takashi; Tanaka, Masaomi; Nomoto, Ken'ichi; Umeda, Hideyuki

    2011-01-01

    We investigate the formation of dust grains in the ejecta of Type Ia supernovae (SNe Ia), adopting the carbon-deflagration W7 model. In the calculations of dust formation, we apply the nucleation and grain growth theory and consider the two cases with and without formation of CO and SiO molecules. The results of the calculations show that for the sticking probability of alpha_j=1, C, silicate, Si, and FeS grains can condense at early times of ~100--300 days after the explosion, whereas Fe and SiC grains cannot form substantially. Due to the low gas density in SNe Ia with no H-envelope, the average radii of the newly formed grains are generally below 0.01 micron, being much smaller than those in Type II-P SNe. This supports our previous conclusion that the radius of dust formed in the ejecta is smaller in SNe with less massive envelopes. The total dust mass ranges from 3x10^{-4} M_sun to 0.2 M_sun for alpha_j=0.1--1, depending on whether or not CO and SiO molecules are formed. We also estimate the optical dept...

  19. Constraints on dark energy with the LOSS SN Ia sample

    CERN Document Server

    Ganeshalingam, Mohan; Filippenko, Alexei V

    2013-01-01

    We present a cosmological analysis of the Lick Observatory Supernova Search (LOSS) Type Ia supernova (SN Ia) photometry sample introduced by Ganeshalingam et al. (2010). These SNe provide an effective anchor point to estimate cosmological parameters when combined with datasets at higher redshift. The data presented by Ganeshalingam et al. (2010) have been rereduced in the natural system of the KAIT and Nickel telescopes to minimise systematic uncertainties. We have run the light-curve-fitting software SALT2 on our natural-system light curves to measure light-curve parameters for LOSS light curves and available SN Ia datasets in the literature. We present a Hubble diagram of 586 SNe in the redshift range z=0.01-1.4 with a residual scatter of 0.176 mag. Of the 226 low-z objects in our sample, 91 objects are from LOSS, including 45 SNe without previously published distances. Assuming a flat Universe, we find that the best fit for the dark energy equation-of-state parameter w = -0.86^+0.13_-0.16 (stat) +- 0.11 (s...

  20. Testing SNe Ia distance measurement methods with SN 2011fe

    CERN Document Server

    Vinko, J; Takats, K; Marion, G H; Hegedus, T; Biro, I B; Borkovits, T; Szegedi-Elek, E; Farkas, A; Klagyivik, P; Kiss, L L; Kovacs, T; Pal, A; Szakats, R; Szalai, N; Szalai, T; Szatmary, K; Szing, A; Vida, K; Wheeler, J C

    2012-01-01

    The nearby, bright, almost completely unreddened Type Ia supernova 2011fe in M101 provides a unique opportunity to test both the precision and the accuracy of the extragalactic distances derived from SNe Ia light curve fitters. We apply the current, public versions of the independent light curve fitting codes MLCS2k2 and SALT2 to compute the true distance modulus of SN 2011fe from high-precision, multi-color (BVRI) light curves. The results from the two fitting codes confirm that 2011fe is a "normal" (not peculiar) and only slightly reddened SN Ia. New unreddened distance moduli are derived as 29.21 +/- 0.07 mag (D \\sim 6.95 +/- 0.23 Mpc, MLCS2k2), and 29.05 +/- 0.07 mag (6.46 +/- 0.21 Mpc, SALT2). Despite the very good fitting quality achieved with both light curve fitters, the resulting distance moduli are inconsistent by 2 sigma. However, both are marginally consistent (at \\sim 1 sigma) with the HST Key Project distance modulus for M101. The SALT2 distance is in good agreement with the recently revised Cep...

  1. IMPROVING COSMOLOGICAL DISTANCE MEASUREMENTS USING TWIN TYPE IA SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Fakhouri, H. K.; Boone, K.; Aldering, G.; Aragon, C.; Bailey, S.; Fagrelius, P. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Fleury, M. [Laboratoire de Physique Nucléaire et des Hautes Énergies, Université Pierre et Marie Curie Paris 6, Université Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Barbary, K. [Department of Physics, University of California Berkeley, 366 LeConte Hall MC 7300, Berkeley, CA 94720-7300 (United States); Baugh, D.; Chen, J. [Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084 (China); Buton, C.; Chotard, N.; Copin, Y. [Université de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, F-69622, Lyon (France); Childress, M. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Feindt, U. [Institut fur Physik, Humboldt-Universitat zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany); Fouchez, D. [Centre de Physique des Particules de Marseille, Aix-Marseille Université, CNRS/IN2P3, 163 avenue de Luminy—Case 902—F-13288 Marseille Cedex 09 (France); Gangler, E. [Clermont Université, Université Blaise Pascal, CNRS/IN2P3, Laboratoire de Physique Corpusculaire, BP 10448, F-63000 Clermont-Ferrand (France); Collaboration: Nearby Supernova Factory; and others

    2015-12-10

    We introduce a method for identifying “twin” Type Ia supernovae (SNe Ia) and using them to improve distance measurements. This novel approach to SN Ia standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). We begin with a well-measured set of SNe, find pairs whose spectra match well across the entire optical window, and then test whether this leads to a smaller dispersion in their absolute brightnesses. This analysis is completed in a blinded fashion, ensuring that decisions made in implementing the method do not inadvertently bias the result. We find that pairs of SNe with more closely matched spectra indeed have reduced brightness dispersion. We are able to standardize this initial set of SNfactory SNe to 0.083 ± 0.012 mag, implying a dispersion of 0.072 ± 0.010 mag in the absence of peculiar velocities. We estimate that with larger numbers of comparison SNe, e.g., using the final SNfactory spectrophotometric data set as a reference, this method will be capable of standardizing high-redshift SNe to within 0.06–0.07 mag. These results imply that at least 3/4 of the variance in Hubble residuals in current SN cosmology analyses is due to previously unaccounted-for astrophysical differences among the SNe.

  2. Turbulence-Flame Interactions in Type Ia Supernovae

    CERN Document Server

    Aspden, A J; Day, M S; Woosley, S E; Zingale, M

    2008-01-01

    The large range of time and length scales involved in type Ia supernovae (SN Ia) requires the use of flame models. As a prelude to exploring various options for flame models, we consider, in this paper, high-resolution three-dimensional simulations of the small-scale dynamics of nuclear flames in the supernova environment in which the details of the flame structure are fully resolved. The range of densities examined, 1 to $8 \\times 10^7$ g cm$^{-3}$, spans the transition from the laminar flamelet regime to the distributed burning regime where small scale turbulence disrupts the flame. The use of a low Mach number algorithm facilitates the accurate resolution of the thermal structure of the flame and the inviscid turbulent kinetic energy cascade, while implicitly incorporating kinetic energy dissipation at the grid-scale cutoff. For an assumed background of isotropic Kolmogorov turbulence with an energy characteristic of SN Ia, we find a transition density between 1 and $3 \\times 10^7$ g cm$^{-3}$ where the na...

  3. Neutronization During Carbon Simmering In Type Ia Supernova Progenitors

    CERN Document Server

    Martínez-Rodríguez, Héctor; Schwab, Josiah; Badenes, Carles

    2016-01-01

    When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ${\\sim} \\,10^{3}-10^{4} \\,$yr of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the \\texttt{MESA} stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and, in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ${\\approx} \\, 3 \\times 10^{-4}$. This is ${\\approx} \\, 8 \\times 10^{-4}$ lower than that found in previo...

  4. Domestication of the dog from the wolf was promoted by enhanced excitatory synaptic plasticity: a hypothesis.

    Science.gov (United States)

    Li, Yan; Wang, Guo-Dong; Wang, Ming-Shan; Irwin, David M; Wu, Dong-Dong; Zhang, Ya-Ping

    2014-11-05

    Dogs shared a much closer relationship with humans than any other domesticated animals, probably due to their unique social cognitive capabilities, which were hypothesized to be a by-product of selection for tameness toward humans. Here, we demonstrate that genes involved in glutamate metabolism, which account partially for fear response, indeed show the greatest population differentiation by whole-genome comparison of dogs and wolves. However, the changing direction of their expression supports a role in increasing excitatory synaptic plasticity in dogs rather than reducing fear response. Because synaptic plasticity are widely believed to be cellular correlates of learning and memory, this change may alter the learning and memory abilities of ancient scavenging wolves, weaken the fear reaction toward humans, and prompt the initial interspecific contact.

  5. BDNF has opposite effects on the quantal amplitude of pyramidal neuron and interneuron excitatory synapses.

    Science.gov (United States)

    Rutherford, L C; Nelson, S B; Turrigiano, G G

    1998-09-01

    Recently, we have identified a novel form of synaptic plasticity that acts to stabilize neocortical firing rates by scaling the quantal amplitude of AMPA-mediated synaptic inputs up or down as a function of neuronal activity. Here, we show that the effects of activity blockade on quantal amplitude are mediated through the neurotrophin brain-derived neurotrophic factor (BDNF). Exogenous BDNF prevented, and a TrkB-IgG fusion protein reproduced, the effects of activity blockade on pyramidal quantal amplitude. BDNF had opposite effects on pyramidal neuron and interneuron quantal amplitudes and modified the ratio of pyramidal neuron to interneuron firing rates. These data demonstrate a novel role for BDNF in the homeostatic regulation of excitatory synaptic strengths and in the maintenance of the balance of cortical excitation and inhibition.

  6. Plasticity of Hippocampal Excitatory-Inhibitory Balance: Missing the Synaptic Control in the Epileptic Brain

    Directory of Open Access Journals (Sweden)

    Christian Bonansco

    2016-01-01

    Full Text Available Synaptic plasticity is the capacity generated by experience to modify the neural function and, thereby, adapt our behaviour. Long-term plasticity of glutamatergic and GABAergic transmission occurs in a concerted manner, finely adjusting the excitatory-inhibitory (E/I balance. Imbalances of E/I function are related to several neurological diseases including epilepsy. Several evidences have demonstrated that astrocytes are able to control the synaptic plasticity, with astrocytes being active partners in synaptic physiology and E/I balance. Here, we revise molecular evidences showing the epileptic stage as an abnormal form of long-term brain plasticity and propose the possible participation of astrocytes to the abnormal increase of glutamatergic and decrease of GABAergic neurotransmission in epileptic networks.

  7. Excitatory actions of gaba during development: the nature of the nurture.

    Science.gov (United States)

    Ben-Ari, Yehezkel

    2002-09-01

    In the immature brain, GABA (gamma-aminobutyric acid) is excitatory, and GABA-releasing synapses are formed before glutamatergic contacts in a wide range of species and structures. GABA becomes inhibitory by the delayed expression of a chloride exporter, leading to a negative shift in the reversal potential for choride ions. I propose that this mechanism provides a solution to the problem of how to excite developing neurons to promote growth and synapse formation while avoiding the potentially toxic effects of a mismatch between GABA-mediated inhibition and glutamatergic excitation. As key elements of this cascade are activity dependent, the formation of inhibition adds an element of nurture to the construction of cortical networks.

  8. Ionotropic excitatory amino acid receptor ligands. Synthesis and pharmacology of a new amino acid AMPA antagonist

    DEFF Research Database (Denmark)

    Madsen, U; Sløk, F A; Stensbøl, T B;

    2000-01-01

    We have previously described the potent and selective (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor agonist, (RS)-2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl)propionic acid (ACPA), and the AMPA receptor antagonist (RS)-2-amino-3-[3-(carboxymethoxy)-5-methyl-4......-isoxazolyl]propionic acid (AMOA). Using these AMPA receptor ligands as leads, a series of compounds have been developed as tools for further elucidation of the structural requirements for activation and blockade of AMPA receptors. The synthesized compounds have been tested for activity at ionotropic...... excitatory amino acid (EAA) receptors using receptor binding and electrophysiological techniques, and for activity at metabotropic EAA receptors using second messenger assays. Compounds 1 and 4 were essentially inactive. (RS)-2-Amino-3-[3-(2-carboxyethyl)-5-methyl-4-isoxazolyl]propionic acid (ACMP, 2...

  9. Chaos and Correlated Avalanches in Excitatory Neural Networks with Synaptic Plasticity

    Science.gov (United States)

    Pittorino, Fabrizio; Ibáñez-Berganza, Miguel; di Volo, Matteo; Vezzani, Alessandro; Burioni, Raffaella

    2017-03-01

    A collective chaotic phase with power law scaling of activity events is observed in a disordered mean field network of purely excitatory leaky integrate-and-fire neurons with short-term synaptic plasticity. The dynamical phase diagram exhibits two transitions from quasisynchronous and asynchronous regimes to the nontrivial, collective, bursty regime with avalanches. In the homogeneous case without disorder, the system synchronizes and the bursty behavior is reflected into a period doubling transition to chaos for a two dimensional discrete map. Numerical simulations show that the bursty chaotic phase with avalanches exhibits a spontaneous emergence of persistent time correlations and enhanced Kolmogorov complexity. Our analysis reveals a mechanism for the generation of irregular avalanches that emerges from the combination of disorder and deterministic underlying chaotic dynamics.

  10. Heterogeneous reallocation of presynaptic efficacy in recurrent excitatory circuits adapting to inactivity.

    Science.gov (United States)

    Mitra, Ananya; Mitra, Siddhartha S; Tsien, Richard W

    2011-12-18

    Recurrent excitatory circuits face extreme challenges in balancing efficacy and stability. We recorded from CA3 pyramidal neuron pairs in rat hippocampal slice cultures to characterize synaptic and circuit-level changes in recurrent synapses resulting from long-term inactivity. Chronic tetrodotoxin treatment greatly reduced the percentage of connected CA3-CA3 neurons, but enhanced the strength of the remaining connections; presynaptic release probability sharply increased, whereas quantal size was unaltered. Connectivity was decreased in activity-deprived circuits by functional silencing of synapses, whereas three-dimensional anatomical analysis revealed no change in spine or bouton density or aggregate dendrite length. The silencing arose from enhanced Cdk5 activity and could be reverted by acute Cdk5 inhibition with roscovitine. Our results suggest that recurrent circuits adapt to chronic inactivity by reallocating presynaptic weights heterogeneously, strengthening certain connections while silencing others. This restricts synaptic output and input, preserving signaling efficacy among a subset of neuronal ensembles while protecting network stability.

  11. Glutathione in Cellular Redox Homeostasis: Association with the Excitatory Amino Acid Carrier 1 (EAAC1

    Directory of Open Access Journals (Sweden)

    Koji Aoyama

    2015-05-01

    Full Text Available Reactive oxygen species (ROS are by-products of the cellular metabolism of oxygen consumption, produced mainly in the mitochondria. ROS are known to be highly reactive ions or free radicals containing oxygen that impair redox homeostasis and cellular functions, leading to cell death. Under physiological conditions, a variety of antioxidant systems scavenge ROS to maintain the intracellular redox homeostasis and normal cellular functions. This review focuses on the antioxidant system’s roles in maintaining redox homeostasis. Especially, glutathione (GSH is the most important thiol-containing molecule, as it functions as a redox buffer, antioxidant, and enzyme cofactor against oxidative stress. In the brain, dysfunction of GSH synthesis leading to GSH depletion exacerbates oxidative stress, which is linked to a pathogenesis of aging-related neurodegenerative diseases. Excitatory amino acid carrier 1 (EAAC1 plays a pivotal role in neuronal GSH synthesis. The regulatory mechanism of EAAC1 is also discussed.

  12. Rhythmic Oscillations of Excitatory Bursting Hodkin-Huxley Neuronal Network with Synaptic Learning.

    Science.gov (United States)

    Shi, Qi; Han, Fang; Wang, Zhijie; Li, Caiyun

    2016-01-01

    Rhythmic oscillations of neuronal network are actually kind of synchronous behaviors, which play an important role in neural systems. In this paper, the properties of excitement degree and oscillation frequency of excitatory bursting Hodkin-Huxley neuronal network which incorporates a synaptic learning rule are studied. The effects of coupling strength, synaptic learning rate, and other parameters of chemical synapses, such as synaptic delay and decay time constant, are explored, respectively. It is found that the increase of the coupling strength can weaken the extent of excitement, whereas increasing the synaptic learning rate makes the network more excited in a certain range; along with the increasing of the delay time and the decay time constant, the excitement degree increases at the beginning, then decreases, and keeps stable. It is also found that, along with the increase of the synaptic learning rate, the coupling strength, the delay time, and the decay time constant, the oscillation frequency of the network decreases monotonically.

  13. Opioid Tolerance and Physical Dependence: Role of Spinal Neuropeptides, Excitatory Amino Acids and Their Messengers

    Directory of Open Access Journals (Sweden)

    Khem Jhamandas

    2000-01-01

    Full Text Available Chronic opioid treatment results in the development of tolerance and physical dependence. The mechanisms underlying opioid tolerance and/or physical dependence are unclear. Recent studies suggest that opioid receptor or nociceptive, neural network-based adaptations contribute to this phenomenon. At the spinal level, the genesis of tolerance and physical dependence is associated with increased excitatory amino acid activity expressed through N-methyl-D-aspartate receptors in the dorsal horn. However, recent evidence also implicates spinal neuropeptide transmitters such as calcitonin gene-related peptide (CGRP and  substance P in the development of opioid tolerance. Long term spinal morphine treatment increases CGRP-like immunostaining in the dorsal horn, and coadministration of morphine with CGRP8-37, a competitive CGRP1 receptor antagonist, prevents this response as well as loss of the analgesic potency. CGRP8-37, like N-methyl-D-aspartate receptor antagonists, has the potential to restore morphine potency in experimental animals who are already tolerant to the opioid agonist. Recent evidence suggests that the effects of excitatory amino acid and neuropeptide receptor activity may be expressed through the generation of messengers such as nitric oxide and prostanoids. Agents that inhibit the synthesis of nitric oxide and prostanoids have the potential to inhibit and reverse spinal opioid tolerance, suggesting that this phenomenon may be expressed through the activity of these mediators. Nociceptive transmission in the dorsal horn of the spinal cord also involves activity of a number of other mediators including morphine modulatory neuropeptides, neuropeptide FF  and neuropeptide SF. The role of these mediators and their relationship with other factors implicated in tolerance remain to be determined.

  14. Neuroligin-1 loss is associated with reduced tenacity of excitatory synapses.

    Directory of Open Access Journals (Sweden)

    Adel Zeidan

    Full Text Available Neuroligins (Nlgns are postsynaptic, integral membrane cell adhesion molecules that play important roles in the formation, validation, and maturation of synapses in the mammalian central nervous system. Given their prominent roles in the life cycle of synapses, it might be expected that the loss of neuroligin family members would affect the stability of synaptic organization, and ultimately, affect the tenacity and persistence of individual synaptic junctions. Here we examined whether and to what extent the loss of Nlgn-1 affects the dynamics of several key synaptic molecules and the constancy of their contents at individual synapses over time. Fluorescently tagged versions of the postsynaptic scaffold molecule PSD-95, the AMPA-type glutamate receptor subunit GluA2 and the presynaptic vesicle molecule SV2A were expressed in primary cortical cultures from Nlgn-1 KO mice and wild-type (WT littermates, and live imaging was used to follow the constancy of their contents at individual synapses over periods of 8-12 hours. We found that the loss of Nlgn-1 was associated with larger fluctuations in the synaptic contents of these molecules and a poorer preservation of their contents at individual synapses. Furthermore, rates of synaptic turnover were somewhat greater in neurons from Nlgn-1 knockout mice. Finally, the increased GluA2 redistribution rates observed in neurons from Nlgn-1 knockout mice were negated by suppressing spontaneous network activity. These findings suggest that the loss of Nlgn-1 is associated with some use-dependent destabilization of excitatory synapse organization, and indicate that in the absence of Nlgn-1, the tenacity of excitatory synapses might be somewhat impaired.

  15. Excitatory effects of parvalbumin-expressing interneurons maintain hippocampal epileptiform activity via synchronous afterdischarges.

    Science.gov (United States)

    Ellender, Tommas J; Raimondo, Joseph V; Irkle, Agnese; Lamsa, Karri P; Akerman, Colin J

    2014-11-12

    Epileptic seizures are characterized by periods of hypersynchronous, hyperexcitability within brain networks. Most seizures involve two stages: an initial tonic phase, followed by a longer clonic phase that is characterized by rhythmic bouts of synchronized network activity called afterdischarges (ADs). Here we investigate the cellular and network mechanisms underlying hippocampal ADs in an effort to understand how they maintain seizure activity. Using in vitro hippocampal slice models from rats and mice, we performed electrophysiological recordings from CA3 pyramidal neurons to monitor network activity and changes in GABAergic signaling during epileptiform activity. First, we show that the highest synchrony occurs during clonic ADs, consistent with the idea that specific circuit dynamics underlie this phase of the epileptiform activity. We then show that ADs require intact GABAergic synaptic transmission, which becomes excitatory as a result of a transient collapse in the chloride (Cl(-)) reversal potential. The depolarizing effects of GABA are strongest at the soma of pyramidal neurons, which implicates somatic-targeting interneurons in AD activity. To test this, we used optogenetic techniques to selectively control the activity of somatic-targeting parvalbumin-expressing (PV(+)) interneurons. Channelrhodopsin-2-mediated activation of PV(+) interneurons during the clonic phase generated excitatory GABAergic responses in pyramidal neurons, which were sufficient to elicit and entrain synchronous AD activity across the network. Finally, archaerhodopsin-mediated selective silencing of PV(+) interneurons reduced the occurrence of ADs during the clonic phase. Therefore, we propose that activity-dependent Cl(-) accumulation subverts the actions of PV(+) interneurons to perpetuate rather than terminate pathological network hyperexcitability during the clonic phase of seizures.

  16. Somatodendritic and excitatory postsynaptic distribution of neuron-type dystrophin isoform, Dp40, in hippocampal neurons

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takahiro; Itoh, Kyoko, E-mail: kxi14@koto.kpu-m.ac.jp; Yaoi, Takeshi; Fushiki, Shinji

    2014-09-12

    Highlights: • Identification of dystrophin (Dp) shortest isoform, Dp40, is a neuron-type Dp. • Dp40 expression is temporally and differentially regulated in comparison to Dp71. • Somatodendritic and nuclear localization of Dp40. • Dp40 is localized to excitatory postsynapses. • Dp40 might play roles in dendritic and synaptic functions. - Abstract: The Duchenne muscular dystrophy (DMD) gene produces multiple dystrophin (Dp) products due to the presence of several promoters. We previously reported the existence of a novel short isoform of Dp, Dp40, in adult mouse brain. However, the exact biochemical expression profile and cytological distribution of the Dp40 protein remain unknown. In this study, we generated a polyclonal antibody against the NH{sub 2}-terminal region of the Dp40 and identified the expression profile of Dp40 in the mouse brain. Through an analysis using embryonic and postnatal mouse cerebrums, we found that Dp40 emerged from the early neonatal stages until adulthood, whereas Dp71, an another Dp short isoform, was highly detected in both prenatal and postnatal cerebrums. Intriguingly, relative expressions of Dp40 and Dp71 were prominent in cultured dissociated neurons and non-neuronal cells derived from mouse hippocampus, respectively. Furthermore, the immunocytological distribution of Dp40 was analyzed in dissociated cultured neurons, revealing that Dp40 is detected in the soma and its dendrites, but not in the axon. It is worthy to note that Dp40 is localized along the subplasmalemmal region of the dendritic shafts, as well as at excitatory postsynaptic sites. Thus, Dp40 was identified as a neuron-type Dp possibly involving dendritic and synaptic functions.

  17. Two classes of excitatory synaptic responses in rat thalamic reticular neurons.

    Science.gov (United States)

    Deleuze, Charlotte; Huguenard, John R

    2016-09-01

    The thalamic reticular nucleus (nRt), composed of GABAergic cells providing inhibition of relay neurons in the dorsal thalamus, receives excitation from the neocortex and thalamus. The two excitatory pathways promoting feedback or feedforward inhibition of thalamocortical neurons contribute to sensory processing and rhythm generation. While synaptic inhibition within the nRt has been carefully characterized, little is known regarding the biophysics of synaptic excitation. To characterize the functional properties of thalamocortical and corticothalamic connections to the nRt, we recorded minimal electrically evoked excitatory postsynaptic currents from nRt cells in vitro. A hierarchical clustering algorithm distinguished two types of events. Type 1 events had larger amplitudes and faster kinetics, largely mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, whereas type 2 responses had more prominent N-methyl-d-aspartate (NMDA) receptor contribution. Type 1 responses showed subnormal axonal propagation and paired pulse depression, consistent with thalamocortical inputs. Furthermore, responses kinetically similar to type 1 events were evoked by glutamate-mediated activation of thalamic neurons. Type 2 responses, in contrast, likely arise from corticothalamic inputs, with larger NMDA conductance and weak Mg(2+)-dependent block, suggesting that NMDA receptors are critical for the cortical excitation of reticular neurons. The long-lasting action of NMDA receptors would promote reticular cell burst firing and produce powerful inhibitory output to relay neurons proposed to be important in triggering epilepsy. This work provides the first complete voltage-clamp analysis of the kinetics and voltage dependence of AMPA and NMDA responses of thalamocortical and corticothalamic synapses in the nRt and will be critical in optimizing biologically realistic neural network models of thalamocortical circuits relevant to sensory processing and

  18. ATP participates in three excitatory postsynaptic potentials in the submucous plexus of the guinea pig ileum.

    Science.gov (United States)

    Monro, R L; Bertrand, P P; Bornstein, J C

    2004-04-15

    Synaptic transmission between neurones intrinsic to the wall of the intestine involves multiple neurotransmitters. This study aimed to identify neurotransmitters responsible for non-cholinergic excitatory synaptic transmission in the submucous plexus of the guinea pig ileum. Intracellular recordings were made from secretomotor and vasodilator neurones. A single electrical stimulus to a fibre tract evoked excitatory postsynaptic potentials (EPSPs) with three different time courses - fast, slow and an EPSP with an intermediate time course (latency 96 ms, duration 1.2 s). In all neurones, blocking nicotinic receptors reduced fast EPSPs, but they were abolished in only 57 of 78 neurones. Fast EPSPs were also reduced by P2 purinoceptor blockade (5 of 27 neurones) or 5-HT(3) receptor blockade (3 of 20 neurones). The intermediate EPSP was abolished by P2 receptor blockade (13 of 13 neurones) or by the specific P2Y(1) receptor antagonist MRS 2179 (5 of 5 neurones) and was always preceded by a nicotinic or mixed nicotinic/purinergic fast EPSP. Intermediate EPSPs were observed in over half of all neurones including most non-cholinergic secretomotor neurones identified by immunoreactivity for vasoactive intestinal peptide. The slow EPSP evoked by a single pulse stimulus was also abolished by P2 receptor blockade (5 of 5 neurones) or by MRS 2179 (3 of 3 neurones). We conclude that fast EPSPs in submucous neurones are mediated by acetylcholine acting at nicotinic receptors, ATP acting at P2X receptors and 5-HT acting at 5-HT(3) receptors. Both the intermediate EPSP and the single stimulus slow EPSP are mediated by ATP acting at P2Y(1) receptors.

  19. Excitatory and inhibitory projections in parallel pathways from the inferior colliculus to the auditory thalamus

    Directory of Open Access Journals (Sweden)

    Jeffrey Garrett Mellott

    2014-11-01

    Full Text Available Individual subdivisions of the medial geniculate body (MG receive a majority of their ascending inputs from 1 or 2 subdivisions of the inferior colliculus (IC. This establishes parallel pathways that provide a model for understanding auditory projections from the IC through the MG and on to auditory cortex. A striking discovery about the tectothalamic circuit was identification of a substantial GABAergic component. Whether GABAergic projections match the parallel pathway organization has not been examined. We asked whether the parallel pathway concept is reflected in guinea pig tectothalamic pathways and to what degree GABAergic cells contribute to each pathway. We deposited retrograde tracers into individual MG subdivisions (ventral, MGv; medial, MGm; dorsal, MGd; suprageniculate, MGsg to label tectothalamic cells and used immunochemistry to identify GABAergic cells. The MGv receives most of its IC input (~75% from the IC central nucleus (ICc; MGd and MGsg receive most of their input (~70% from IC dorsal cortex (ICd; and MGm receives substantial input from both ICc (~40% and IC lateral cortex (~40%. Each MG subdivision receives additional input (up to 32% from non-dominant IC subdivisions, suggesting cross-talk between the pathways. The proportion of GABAergic cells in each pathway depended on the MG subdivision. GABAergic cells formed ~20% of IC inputs to MGv or MGm, ~11% of inputs to MGd, and 4% of inputs to MGsg. Thus, non-GABAergic (i.e., glutamatergic cells are most numerous in each pathway with GABAergic cells contributing to different extents. Despite smaller numbers of GABAergic cells, their distributions across IC subdivisions mimicked the parallel pathways. Projections outside the dominant pathways suggest opportunities for excitatory and inhibitory crosstalk. The results demonstrate parallel tectothalamic pathways in guinea pigs and suggest numerous opportunities for excitatory and inhibitory interactions within and between pathways.

  20. Training Excitatory-Inhibitory Recurrent Neural Networks for Cognitive Tasks: A Simple and Flexible Framework.

    Directory of Open Access Journals (Sweden)

    H Francis Song

    2016-02-01

    Full Text Available The ability to simultaneously record from large numbers of neurons in behaving animals has ushered in a new era for the study of the neural circuit mechanisms underlying cognitive functions. One promising approach to uncovering the dynamical and computational principles governing population responses is to analyze model recurrent neural networks (RNNs that have been optimized to perform the same tasks as behaving animals. Because the optimization of network parameters specifies the desired output but not the manner in which to achieve this output, "trained" networks serve as a source of mechanistic hypotheses and a testing ground for data analyses that link neural computation to behavior. Complete access to the activity and connectivity of the circuit, and the ability to manipulate them arbitrarily, make trained networks a convenient proxy for biological circuits and a valuable platform for theoretical investigation. However, existing RNNs lack basic biological features such as the distinction between excitatory and inhibitory units (Dale's principle, which are essential if RNNs are to provide insights into the operation of biological circuits. Moreover, trained networks can achieve the same behavioral performance but differ substantially in their structure and dynamics, highlighting the need for a simple and flexible framework for the exploratory training of RNNs. Here, we describe a framework for gradient descent-based training of excitatory-inhibitory RNNs that can incorporate a variety of biological knowledge. We provide an implementation based on the machine learning library Theano, whose automatic differentiation capabilities facilitate modifications and extensions. We validate this framework by applying it to well-known experimental paradigms such as perceptual decision-making, context-dependent integration, multisensory integration, parametric working memory, and motor sequence generation. Our results demonstrate the wide range of neural

  1. Adolescent chronic mild stress alters hippocampal CB1 receptor-mediated excitatory neurotransmission and plasticity.

    Science.gov (United States)

    Reich, C G; Mihalik, G R; Iskander, A N; Seckler, J C; Weiss, M S

    2013-12-03

    Endocannabinoids (eCBs) are involved in the stress response and alterations in eCB signaling may contribute to the etiology of mood disorders. Exposure to chronic mild stress (CMS), a model of depression, produces downregulation of the cannabinoid 1 (CB1) receptor in the hippocampus of male rats. However, it is unknown how this stress-induced change in CB1 levels affects eCB-mediated neurotransmission. In vitro, field potential recordings from CMS-exposed (21-days) rats were performed to assess the effects of stress on eCB-regulated glutamatergic neurotransmission in/on hippocampal area CA1. We observed that application of the CB1 agonist, WIN 55,212-5 (1 μM), in stress animals resulted in a ∼135% increase in excitatory neurotransmission, whereas CB1 activation in non-stress animals leads to a ∼30% decrease. However, during blockade of GABA(A) neurotransmission with picrotoxin, CB1 activation yielded a ∼35% decrease in stress animals. These findings indicate that CMS does not directly affect glutamatergic neurotransmission. Rather, CMS sensitizes CB1 function on GABAergic terminals, leading to less inhibition and an increase in excitatory neurotransmission. This finding is reinforced in that induction of weak long-term-potentiation (LTP) is enhanced in CMS-exposed animals compared to controls and this enhancement is CB1-dependent. Lastly, we observed that the LTP-blocking property of WIN 55,212-5 shifts from being glutamate-dependent in non-stress animals to being GABA-dependent in stress animals. These results effectively demonstrate that CMS significantly alters hippocampal eCB-mediated neurotransmission and synaptic plasticity.

  2. Dynamics of networks of excitatory and inhibitory neurons in response to time-dependent inputs.

    Science.gov (United States)

    Ledoux, Erwan; Brunel, Nicolas

    2011-01-01

    We investigate the dynamics of recurrent networks of excitatory (E) and inhibitory (I) neurons in the presence of time-dependent inputs. The dynamics is characterized by the network dynamical transfer function, i.e., how the population firing rate is modulated by sinusoidal inputs at arbitrary frequencies. Two types of networks are studied and compared: (i) a Wilson-Cowan type firing rate model; and (ii) a fully connected network of leaky integrate-and-fire (LIF) neurons, in a strong noise regime. We first characterize the region of stability of the "asynchronous state" (a state in which population activity is constant in time when external inputs are constant) in the space of parameters characterizing the connectivity of the network. We then systematically characterize the qualitative behaviors of the dynamical transfer function, as a function of the connectivity. We find that the transfer function can be either low-pass, or with a single or double resonance, depending on the connection strengths and synaptic time constants. Resonances appear when the system is close to Hopf bifurcations, that can be induced by two separate mechanisms: the I-I connectivity and the E-I connectivity. Double resonances can appear when excitatory delays are larger than inhibitory delays, due to the fact that two distinct instabilities exist with a finite gap between the corresponding frequencies. In networks of LIF neurons, changes in external inputs and external noise are shown to be able to change qualitatively the network transfer function. Firing rate models are shown to exhibit the same diversity of transfer functions as the LIF network, provided delays are present. They can also exhibit input-dependent changes of the transfer function, provided a suitable static non-linearity is incorporated.

  3. Dynamics of networks of excitatory and inhibitory neuronsin response to time-dependent inputs

    Directory of Open Access Journals (Sweden)

    Erwan eLedoux

    2011-05-01

    Full Text Available We investigate the dynamics of recurrent networks of excitatory (E and inhibitory(I neurons in the presence of time-dependent inputs. The dynamics is characterizedby the network dynamical transfer function, i.e. how the population firing rate ismodulated by sinusoidal inputs at arbitrary frequencies. Two types of networks arestudied and compared: (i a Wilson-Cowan type firing rate model; and (ii a fullyconnected network of leaky integrate-and-fire neurons, in a strong noise regime. Wefirst characterize the region of stability of the ‘asynchronous state’ (a state in whichpopulation activity is constant in time when external inputs are constant in the spaceof parameters characterizing the connectivity of the network. We then systematicallycharacterize the qualitative behaviors of the dynamical transfer function, as a functionof the connectivity. We find that the transfer function can be either low-pass, or witha single or double resonance, depending on the connection strengths and synaptic timeconstants. Resonances appear when the system is close to Hopf bifurcations, that canbe induced by two separate mechanisms: the I-I connectivity and the E-I connectivity.Double resonances can appear when excitatory delays are larger than inhibitory delays,due to the fact that two distinct instabilities exist with a finite gap between thecorresponding frequencies. In networks of LIF neurons, changes in external inputs andexternal noise are shown to be able to change qualitatively the network transfer function.Firing rate models are shown to exhibit the same diversity of transfer functions asthe LIF network, provided delays are present. They can also exhibit input-dependentchanges of the transfer function, provided a suitable static nonlinearity is incorporated.

  4. Dynamics of excitatory synaptic components in sustained firing at low rates.

    Science.gov (United States)

    Wyart, Claire; Cocco, Simona; Bourdieu, Laurent; Léger, Jean-Francois; Herr, Catherine; Chatenay, Didier

    2005-06-01

    Sustained firing is necessary for the persistent activity associated with working memory. The relative contributions of the reverberation of excitation and of the temporal dynamics of the excitatory postsynaptic potential (EPSP) to the maintenance of activity are difficult to evaluate in classical preparations. We used simplified models of synchronous excitatory networks, hippocampal autapses and pairs, to study the synaptic mechanisms underlying firing at low rates. Calcium imaging and cell attached recordings showed that these neurons spontaneously fired bursts of action potentials that lasted for seconds over a wide range of frequencies. In 2-wk-old cells, the median firing frequency was low (11 +/- 8.8 Hz), whereas in 3- to 4-wk-old cells, it decreased to a very low value (2 +/- 1.3 Hz). In both cases, we have shown that the slowest synaptic component supported firing. In 2-wk-old autapses, antagonists of N-methyl-d-aspartate receptors (NMDARs) induced rare isolated spikes showing that the NMDA component of the EPSP was essential for bursts at low frequency. In 3- to 4-wk-old neurons, the very low frequency firing was maintained without the NMDAR activation. However EGTA-AM or alpha-methyl-4-carboxyphenylglycine (MCPG) removed the very slow depolarizing component of the EPSP and prevented the sustained firing at very low rate. A metabotropic glutamate receptor (mGluR)-activated calcium sensitive conductance is therefore responsible for a very slow synaptic component associated with firing at very low rate. In addition, our observations suggested that the asynchronous release of glutamate might participate also in the recurring bursting.

  5. GABA B receptor modulation of excitatory and inhibitory synaptic transmission onto rat CA3 hippocampal interneurons.

    Science.gov (United States)

    Lei, Saobo; McBain, Chris J

    2003-01-15

    Hippocampal stratum radiatum inhibitory interneurons receive glutamatergic excitatory innervation via the recurrent collateral fibers of CA3 pyramidal neurons and GABAergic inhibition from other interneurons. We examined both presynaptic- and postsynaptic-GABA(B) receptor-mediated responses at both synapse types. Postsynaptic GABA(B) receptor-mediated responses were absent in recordings from young (P16-18) but present in recordings from older animals (> or =P30) suggesting developmental regulation. In young animals, the GABA(B) receptor agonist, baclofen, inhibited the amplitude of evoked EPSCs and IPSCs, an effect blocked by prior application of the selective antagonist CGP55845. Baclofen enhanced the paired-pulse ratio and coefficient of variation of evoked EPSCs and IPSCs, consistent with a presynaptic mechanism of regulation. In addition, baclofen reduced the frequency of miniature IPSCs but not mEPSCs. However, baclofen reduced the frequency of KCl-induced mEPSCs; an effect blocked by Cd(2+), implicating presynaptic voltage-gated Ca(2+) channels as a target for baclofen modulation. In contrast, although Cd(2+) prevented the KCl-induced increase in mIPSC frequency, it failed to block baclofen's reduction of mIPSC frequency. Whereas N- and P/Q-types of Ca(2+) channels contributed equally to GABA(B) receptor-mediated inhibition of EPSCs, more P/Q-type Ca(2+) channels were involved in GABA(B) receptor-mediated inhibition of IPSCs. Finally, baclofen blocked the frequency-dependent depression of EPSCs and IPSCs, but was less effective at blocking frequency-dependent facilitation of EPSCs. Our results demonstrate that presynaptic GABA(B) receptors are expressed on the terminals of both excitatory and inhibitory synapses onto CA3 interneurons and that their activation modulates essential components of the release process underlying transmission at these two synapse types.

  6. Training Excitatory-Inhibitory Recurrent Neural Networks for Cognitive Tasks: A Simple and Flexible Framework.

    Science.gov (United States)

    Song, H Francis; Yang, Guangyu R; Wang, Xiao-Jing

    2016-02-01

    The ability to simultaneously record from large numbers of neurons in behaving animals has ushered in a new era for the study of the neural circuit mechanisms underlying cognitive functions. One promising approach to uncovering the dynamical and computational principles governing population responses is to analyze model recurrent neural networks (RNNs) that have been optimized to perform the same tasks as behaving animals. Because the optimization of network parameters specifies the desired output but not the manner in which to achieve this output, "trained" networks serve as a source of mechanistic hypotheses and a testing ground for data analyses that link neural computation to behavior. Complete access to the activity and connectivity of the circuit, and the ability to manipulate them arbitrarily, make trained networks a convenient proxy for biological circuits and a valuable platform for theoretical investigation. However, existing RNNs lack basic biological features such as the distinction between excitatory and inhibitory units (Dale's principle), which are essential if RNNs are to provide insights into the operation of biological circuits. Moreover, trained networks can achieve the same behavioral performance but differ substantially in their structure and dynamics, highlighting the need for a simple and flexible framework for the exploratory training of RNNs. Here, we describe a framework for gradient descent-based training of excitatory-inhibitory RNNs that can incorporate a variety of biological knowledge. We provide an implementation based on the machine learning library Theano, whose automatic differentiation capabilities facilitate modifications and extensions. We validate this framework by applying it to well-known experimental paradigms such as perceptual decision-making, context-dependent integration, multisensory integration, parametric working memory, and motor sequence generation. Our results demonstrate the wide range of neural activity patterns

  7. Corticotropin releasing factor dose-dependently modulates excitatory synaptic transmission in the noradrenergic nucleus locus coeruleus.

    Science.gov (United States)

    Prouty, Eric W; Waterhouse, Barry D; Chandler, Daniel J

    2017-03-01

    The noradrenergic nucleus locus coeruleus (LC) is critically involved in the stress response and receives afferent input from a number of corticotropin releasing factor (CRF) containing structures. Several in vivo and in vitro studies in rat have shown that CRF robustly increases the firing rate of LC neurons in a dose-dependent manner. While it is known that these increases are dependent on CRF receptor subtype 1 and mediated by effects of cAMP intracellular signaling cascades on potassium conductance, the impact of CRF on synaptic transmission within LC has not been clarified. In the present study, we used whole-cell patch clamp electrophysiology to assess how varying concentrations of bath-applied CRF affect AMPA-receptor dependent spontaneous excitatory post-synaptic currents (sEPSCs). Compared to vehicle, 10, 25, and 100 nm CRF had no significant effects on any sEPSC parameters. Fifty nanomolar CRF, however, significantly increased sEPSC amplitude, half-width, and charge transfer, while these measures were significantly decreased by 200 nm CRF. These observations suggest that stress may differentially affect ongoing excitatory synaptic transmission in LC depending on how much CRF is released from presynaptic terminals. Combined with the well-documented effects of CRF on membrane properties and spontaneous LC discharge, these observations may help explain how stress and CRF release are able to modulate the signal to noise ratio of LC neurons. These findings have implications for how stress affects the fidelity of signal transmission and information flow through LC and how it might impact norepinephrine release in the CNS.

  8. Hyperactivity of Newborn Pten Knock-out Neurons Results from Increased Excitatory Synaptic Drive

    Science.gov (United States)

    Williams, Michael R.; DeSpenza, Tyrone; Li, Meijie; Gulledge, Allan T.

    2015-01-01

    Developing neurons must regulate morphology, intrinsic excitability, and synaptogenesis to form neural circuits. When these processes go awry, disorders, including autism spectrum disorder (ASD) or epilepsy, may result. The phosphatase Pten is mutated in some patients having ASD and seizures, suggesting that its mutation disrupts neurological function in part through increasing neuronal activity. Supporting this idea, neuronal knock-out of Pten in mice can cause macrocephaly, behavioral changes similar to ASD, and seizures. However, the mechanisms through which excitability is enhanced following Pten depletion are unclear. Previous studies have separately shown that Pten-depleted neurons can drive seizures, receive elevated excitatory synaptic input, and have abnormal dendrites. We therefore tested the hypothesis that developing Pten-depleted neurons are hyperactive due to increased excitatory synaptogenesis using electrophysiology, calcium imaging, morphological analyses, and modeling. This was accomplished by coinjecting retroviruses to either “birthdate” or birthdate and knock-out Pten in granule neurons of the murine neonatal dentate gyrus. We found that Pten knock-out neurons, despite a rapid onset of hypertrophy, were more active in vivo. Pten knock-out neurons fired at more hyperpolarized membrane potentials, displayed greater peak spike rates, and were more sensitive to depolarizing synaptic input. The increased sensitivity of Pten knock-out neurons was due, in part, to a higher density of synapses located more proximal to the soma. We determined that increased synaptic drive was sufficient to drive hypertrophic Pten knock-out neurons beyond their altered action potential threshold. Thus, our work contributes a developmental mechanism for the increased activity of Pten-depleted neurons. PMID:25609613

  9. Coréia aguda na gravidez Acute chorea in pregnancy: comments on twelve consecutive cases

    Directory of Open Access Journals (Sweden)

    Walter C. Pereira

    1967-12-01

    Full Text Available São apresentados doze casos de coréia aguda observados entre 150.000 gestantes (1/12.500. A maioria dos surtos ocorreu no segundo trimestre da primeira gravidez. A duração média dos sintomas foi de três meses, não tendo sido registrado caso algum de óbito materno. Todos os partos foram espontâneos e normais. Houve apenas um óbito fetal conseqüente a choque hemorrágico. São tecidas considerações a propósito dos aspectos clínico, laboratorial e prognóstico da coréia gravídica, sendo focalizado mais pormenorizadamente o problema fisiopatogênico dessa afecção.Twelve consecutive cases of acute chorea occurring among 150.000 pregnant women (1/12.500 are reported. Most of the cases occurred from the fourth do the sixth month of the first pregnancy. The average duration of the symptoms was of three months and no one case of maternal death was verified in the group. The deliveries were spontaneous and normal in all the patients. Only one case of fetal death occurred in consequence of a hemorragic shock. Comments are made on the clinical, laboratorial and prognostic features of chorea gravidarum, being particulary focused the physiopathogenic problem of this condtion.

  10. The Type Ia Supernova 1998bu in M96 and the Hubble Constant

    CERN Document Server

    Jha, S; Kirshner, R P; Challis, P M; Soderberg, A M; Macri, L M; Huchra, J P; Barmby, P; Barton, E J; Berlind, P; Brown, W; Caldwell, N; Calkins, M; Kannappan, S J; Koranyi, D M; Pahre, M A; Rines, K; Stanek, K Z; Stefanik, R; Szentgyorgyi, A H; Väisänen, P; Wang, Z; Zajac, J; Riess, A; Filippenko, A V; Li, W; Modjaz, M; Treffers, R R; Hergenrother, C; Grebel, E K; Seitzer, P; Jacoby, G; Benson, P; Rizvi, A; Marschall, L A; Goldader, J D; Beasley, M; Vacca, W D; Leibundgut, B; Spyromilio, J; Schmidt, B; Wood, P

    1999-01-01

    We present optical and near-infrared photometry and spectroscopy of the type Ia SN 1998bu in the Leo I Group galaxy M96 (NGC 3368). The data set consists of 356 photometric measurements and 29 spectra of SN 1998bu between UT 1998 May 11 and July 15. The well-sampled light curve indicates the supernova reached maximum light in B on UT 1998 May 19.3 (JD 2450952.8 +/- 0.8) with B = 12.22 +/- 0.03 and V = 11.88 +/- 0.02. Application of a revised version of the Multicolor Light Curve Shape (MLCS) method yields an extinction toward the supernova of A_V = 0.94 +/- 0.15 mag, and indicates the supernova was of average luminosity compared to other normal type Ia supernovae. Using the HST Cepheid distance modulus to M96 (Tanvir et al. 1995) and the MLCS fit parameters for the supernova, we derive an extinction-corrected absolute magnitude for SN 1998bu at maximum, M_V = -19.42 +/- 0.22. Our independent results for this supernova are consistent with those of Suntzeff et al. (1999). Combining SN 1998bu with three other we...

  11. Evaluating Systematic Dependencies of Type Ia Supernovae: The Influence of Central Density

    CERN Document Server

    Krueger, Brendan K; Calder, Alan C; Townsley, Dean M; Brown, Edward F; Timmes, Francis X

    2012-01-01

    We present a study exploring a systematic effect on the brightness of type Ia supernovae using numerical models that assume the single-degenerate paradigm. Our investigation varied the central density of the progenitor white dwarf at flame ignition, and considered its impact on the explosion yield, particularly the production and distribution of radioactive Ni-56, which powers the light curve. We performed a suite of two-dimensional simulations with randomized initial conditions, allowing us to characterize the statistical trends that we present. The simulations indicate that production of Fe-group material is statistically independent of progenitor central density, but the mass of stable Fe-group isotopes is tightly correlated with central density, with a decrease in the production of Ni-56 at higher central densities. These results imply progenitors with higher central densities produce dimmer events. We provide details of the post-explosion distribution of Ni-56 in the models, including the lack of a consi...

  12. As identidades ficcionais de Raul Pompéia

    Directory of Open Access Journals (Sweden)

    Franco Baptista Sandanello

    2014-12-01

    Full Text Available A fortuna crítica da obra de Raul Pompéia – especialmente, de seu romance O Ateneu – foi marcada por uma forte aproximação entre a vida do escritor e sua ficção. No entanto, pouco se falou a respeito de um aspecto muito curioso desta relação complexa entre vida e arte: o papel subsequente de Pompéia na literatura brasileira não como escritor, mas como personagem. Curiosamente, o romancista integra a trama de obras ficcionais como, por exemplo, Tentação, de Adolfo Caminha, O canudo, de Afonso Schmidt, e Investigação sobre Ariel, de Sílvio Fiorani. Nesse sentido, a partir de uma comparação entre estas obras, será discutida a possível figuração ficcional de Pompéia, assim como a posição particular de sua subjetividade dentro da mecânica narrativa de cada texto. Do primeiro ao último, há, por assim dizer, um progressivo distanciamento do universo ficcional por ele   criado (como o do citado O Ateneu e uma ênfase cada vez    maior em suas crises e inquietações pessoais. The critical reception of Raul Pompéia’s work – especially that of O Ateneu – has strongly identified over the years his biography to his fiction. However, very little was said on a    very peculiar aspect of this complex link between life and art: the subsequent role of Pompéia in Brazilian literature not as a    writer, but as a fictional character. Curiously, the writer integrates the plot of fictional works such as Tentação, by Adolfo Caminha, O canudo, by Afonso Schmidt, and Investigação sobre Ariel, by Sílvio Fiorani. In this regard, from an initial comparison of these texts, this article discusses the fictional figure of Pompéia, as well as the particular standing of his subjectivity in each narrative. So to speak, in these texts there is a gradual detachment of the fictional universe of his own    works (as that of O Ateneu and an increasing emphasis on his personal dramas and crisis.

  13. IA-2β, but not IA-2, is induced by ghrelin and inhibits glucose-stimulated insulin secretion

    OpenAIRE

    Doi, Asako; Shono, Takeshi; Nishi, Masahiro; Furuta, Hiroto; Sasaki, Hideyuki; Nanjo, Kishio

    2006-01-01

    Ghrelin is a newly discovered peptide and an endogenous ligand for growth hormone (GH) secretagogue (GHS) receptor. It has been shown to possess various central and peripheral effects, including GH secretion, food intake, and gastric and cardiac effects. Ghrelin and the GHS receptor are expressed also in pancreatic islets. We have identified several ghrelin-induced genes by PCR-select subtraction methods, among which is a β-cell autoantigen for type 1 diabetes, IA-2β. Administration of ghreli...

  14. Identification of EhTIF-IA: The putative E. histolytica orthologue of the human ribosomal RNA transcription initiation factor-IA

    Indian Academy of Sciences (India)

    Ankita Srivastava; Alok Bhattacharya; Sudha Bhattacharya; Gagan Deep Jhingan

    2016-03-01

    Initiation of rDNA transcription requires the assembly of a specific multi-protein complex at the rDNA promoter containing the RNA Pol I with auxiliary factors. One of these factors is known as Rrn3P in yeast and Transcription Initiation Factor IA (TIF-IA) in mammals. Rrn3p/TIF-IA serves as a bridge between RNA Pol I and the pre-initiation complex at the promoter. It is phosphorylated at multiple sites and is involved in regulation of rDNA transcription in a growth-dependent manner. In the early branching parasitic protist Entamoeba histolytica, the rRNA genes are present exclusively on circular extra chromosomal plasmids. The protein factors involved in regulation of rDNA transcription in E. histolytica are not known. We have identified the E. histolytica equivalent of TIF-1A (EhTIF-IA) by homology search within the database and was further cloned and expressed. Immuno-localization studies showed that EhTIF-IA co-localized partially with fibrillarin in the peripherally localized nucleolus. EhTIF-IA was shown to interact with the RNA Pol I-specific subunit RPA12 both in vivo and in vitro. Mass spectroscopy data identified RNA Pol I-specific subunits and other nucleolar proteins to be the interacting partners of EhTIF-IA. Our study demonstrates for the first time a conserved putative RNA Pol I transcription factor TIF-IA in E. histolytica.

  15. Identification of EhTIF-IA: The putative E. histolytica orthologue of the human ribosomal RNA transcription initiation factor-IA.

    Science.gov (United States)

    Srivastava, Ankita; Bhattacharya, Alok; Bhattacharya, Sudha; Jhingan, Gagan Deep

    2016-03-01

    Initiation of rDNA transcription requires the assembly of a specific multi-protein complex at the rDNA promoter containing the RNA Pol I with auxiliary factors. One of these factors is known as Rrn3P in yeast and Transcription Initiation Factor IA (TIF-IA) in mammals. Rrn3p/TIF-IA serves as a bridge between RNA Pol I and the pre-initiation complex at the promoter. It is phosphorylated at multiple sites and is involved in regulation of rDNA transcription in a growth-dependent manner. In the early branching parasitic protist Entamoeba histolytica, the rRNA genes are present exclusively on circular extra chromosomal plasmids. The protein factors involved in regulation of rDNA transcription in E. histolytica are not known. We have identified the E. histolytica equivalent of TIF-1A (EhTIF-IA) by homology search within the database and was further cloned and expressed. Immuno-localization studies showed that EhTIF-IA co-localized partially with fibrillarin in the peripherally localized nucleolus. EhTIF-IA was shown to interact with the RNA Pol I-specific subunit RPA12 both in vivo and in vitro. Mass spectroscopy data identified RNA Pol I-specific subunits and other nucleolar proteins to be the interacting partners of EhTIF-IA. Our study demonstrates for the first time a conserved putative RNA Pol I transcription factor TIF-IA in E. histolytica.

  16. Bioavailability Studies and in vitro Profiling of the Selective Excitatory Amino Acid Transporter Subtype 1 (EAAT1) Inhibitor UCPH‐102

    DEFF Research Database (Denmark)

    Haym, Isabell; Huynh, Tri H. V.; Hansen, Stinne W.

    2016-01-01

    Although the selective excitatory amino acid transporter subtype 1 (EAAT1) inhibitor UCPH‐101 has become a standard pharmacological tool compound for in vitro and ex vivo studies in the EAAT research field, its inability to penetrate the blood–brain barrier makes it unsuitable for in vivo studies...

  17. Superficially projecting principal neurons in layer V of medial entorhinal cortex in the rat receive excitatory retrosplenial input.

    Science.gov (United States)

    Czajkowski, Rafał; Sugar, Jørgen; Zhang, Sheng-Jia; Couey, Jonathan J; Ye, Jing; Witter, Menno P

    2013-10-01

    Principal cells in layer V of the medial entorhinal cortex (MEC) have a nodal position in the cortical-hippocampal network. They are the main recipients of hippocampal output and receive inputs from several cortical areas, including a prominent one from the retrosplenial cortex (RSC), likely targeting basal dendrites of layer V neurons. The latter project to extrahippocampal structures but also relay information to the superficial layers of MEC, closing the hippocampal-entorhinal loop. In the rat, we electrophysiologically and morphologically characterized RSC input into MEC and conclude that RSC provides an excitatory input to layer V pyramidal cells. Ultrastructural analyses of anterogradely labeled RSC projections showed that RSC axons in layer V of MEC form predominantly asymmetrical, likely excitatory, synapses on dendritic spines (90%) or shafts (8%), with 2% symmetrical, likely inhibitory, synapses on shafts and spines. The overall excitatory nature of the RSC input was confirmed by an optogenetic approach. Patterned laser stimulation of channelrhodopsin-expressing presynaptic RSC axons evoked exclusively EPSPs in recorded postsynaptic layer V cells. All responding layer V pyramidal cells had an axon extending toward the white matter. Half of these neurons also sent an axon to superficial layers. Confocal imaging of RSC synapses onto MEC layer V neurons shown to project superficially by way of retrogradely labeling from superficial layers confirmed that proximal dendrites of superficially projecting cells are among the targets of inputs from RSC. The excitatory RSC input thus interacts with both entorhinal-cortical and entorhinal-hippocampal circuits.

  18. Excitatory amino acid transporters EAAT-1 and EAAT-2 in temporal lobe and hippocampus in intractable temporal lobe epilepsy

    DEFF Research Database (Denmark)

    Sarac, Sinan; Afzal, Shoaib; Broholm, Helle;

    2009-01-01

    extra-cellular clearance of glutamate by excitatory amino acid transporters (EAAT-1 to EAAT-5). EAAT-1 and EAAT-2 are mainly expressed on astroglial cells for the reuptake of glutamate from the extra-cellular space. We have studied the expression of EAAT-1 and EAAT-2 in the hippocampus and temporal lobe...

  19. Abundance stratification in Type Ia supernovae - V. SN 1986G bridging the gap between normal and subluminous SNe Ia

    CERN Document Server

    Ashall, C; Pian, E; James, P A

    2016-01-01

    A detailed spectroscopic analysis of SN 1986G has been performed. SN 1986G `bridges the gap' between normal and sub luminous type Ia supernova (SNe Ia). The abundance tomography technique is used to determine the abundance distribution of the elements in the ejecta. SN 1986G was found to be a low energy Chandrasekhar mass explosion. Its kinetic energy was 70% of the standard W7 model (0.9x10$^{51}$erg). Oxygen dominates the ejecta from the outermost layers down to $\\sim$9000kms$^{-1}$ , intermediate mass elements (IME) dominate from $\\sim$ 9000kms$^{-1}$ to $\\sim$ 3500kms$^{-1}$ with Ni and Fe dominating the inner layers $<\\sim$ 3500kms$^{-1}$. The final masses of the main elements in the ejecta were found to be, O=0.33M, IME=0.69M, stable NSE=0.21M, $^{56}$Ni=0.14M. An upper limit of the carbon mass is set at C=0.02M. The spectra of SN1986G consist of almost exclusively singly ionised species. SN1986G can be thought of as a low luminosity extension of the main population of SN Ia, with a large deflagratio...

  20. Boracéia Biological Station: an ornithological review

    Directory of Open Access Journals (Sweden)

    Vagner Cavarzere

    2010-01-01

    Full Text Available Boracéia Biological Station, near the city of Salesópolis, SP, is located in one of the most well-defined centers of endemism in eastern Brazil - the Serra do Mar Center. While the station was established only in 1954 under the auspices of the Museu de Zoologia da Universidade de São Paulo, the avifauna of this locality had already attracted the attention of ornithologists by the 1940s, when the first specimens were collected. Here we describe the ornithological history of the Boracéia Biological Station with a review of all the bird species recorded during more than 68 years, including recent transect and mist-netting records. Boracéia's records were found in museums, literature and unpublished reports that totaled 323 bird species when recent data is also considered. Of these, 117 are endemic to the Atlantic forest and 28 are threatened in the state. Although there are a few doubtful records that need to be checked, some species are the only sightings in the state. Boracéia includes a recently discovered species near the station site and is extremely important for the conservation of Atlantic forest birds.A Estação Biológica de Boracéia, localizada em Salesópolis, SP, situa-se na Serra do Mar, importante região biogeográfica e um dos centros de endemismo mais bem definidos do Brasil. Apesar de instituída em 1954, quando passou a pertencer ao Museu de Zoologia da Universidade de São Paulo, a avifauna desta localidade já era objeto de pesquisas desde a década de 1940, época em que foram realizadas as primeiras coletas de aves. Aqui é apresentada pela primeira vez uma revisão de todos os registros avifaunísticos realizados nessa localidade ao longo de mais de 68 anos assim como a adição de novos registros com base em dados coletados recentemente com transectos lineares e redes de neblina. Os registros para Boracéia estiveram representados em museus, na literatura e em dados não publicados que, somados aos registros