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Sample records for proton-rich nucleus 24si

  1. Spectroscopic studies on light proton-rich nuclei

    SciTech Connect

    Guimaraes, V.; Lichtenthaler, R.; Kubono, S.; Tanaka, M. H.; Nomura, T.; Katayama, I.; Kato, S.

    2007-02-12

    A systematic for the light proton rich nuclei with constant TZ = -3/2 isospin is proposed, where a survey on their structure have shown interesting features. Preliminary results of a re-analysis on the sctructure of 13O nucleus is also presented. This 13O nucleus have been investigated by the 3-neutron pick up (3He,6He) reaction, and new levels have been assigned for this nucleus.

  2. Mass Evaluation for Proton Rich Nuclides

    SciTech Connect

    Wang, M.; Audi, G.; Xu, X.; Pfeiffer, B.; Kondev, F. G.

    2011-11-30

    The Atomic mass evaluation (AME) provides the reliable resource for the values related to atomic masses. Since the publication of the latest version of AME in 2003, many developments for atomic mass determination have been done and important results changed significantly our knowledge. A preliminary version of AME was released in April 2011, and an official version is foreseen to be published in early 2013. The general status of AME is presented and some specific features of AME for proton-rich nuclides are discussed.

  3. Three-Body Forces and Proton-Rich Nuclei

    SciTech Connect

    Holt, Jason D; Menendez, J.

    2013-01-01

    We present the first study of three-nucleon (3N) forces for proton-rich nuclei along the N 8 and N 20 isotones. Our results for the ground-state energies and proton separation energies are in very good agreement with experiment where available, and with the empirical isobaric multiplet mass equation. We predict the spectra for all N 8 and N 20 isotones to the proton dripline, which agree well with experiment for 18Ne, 19Na, 20Mg and 42Ti. In all other cases, we provide first predictions based on nuclear forces. Our results are also very promising for studying isospin symmetry breaking in medium-mass nuclei based on chiral effective field theory.

  4. New type of asymmetric fission in proton-rich nuclei.

    PubMed

    Andreyev, A N; Elseviers, J; Huyse, M; Van Duppen, P; Antalic, S; Barzakh, A; Bree, N; Cocolios, T E; Comas, V F; Diriken, J; Fedorov, D; Fedosseev, V; Franchoo, S; Heredia, J A; Ivanov, O; Köster, U; Marsh, B A; Nishio, K; Page, R D; Patronis, N; Seliverstov, M; Tsekhanovich, I; Van den Bergh, P; Van De Walle, J; Venhart, M; Vermote, S; Veselsky, M; Wagemans, C; Ichikawa, T; Iwamoto, A; Möller, P; Sierk, A J

    2010-12-17

    A very exotic process of β-delayed fission of 180Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post-β-decay daughter nucleus 180Hg (N/Z=1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two 90Zr fragments, with magic N=50 and semimagic Z=40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly measured branching ratio for β-delayed fission of 180Tl is 3.6(7) × 10(-3)%, approximately 2 orders of magnitude larger than in an earlier study. PMID:21231583

  5. The production of proton-rich isotopes beyond iron: The γ-process in stars

    NASA Astrophysics Data System (ADS)

    Pignatari, Marco; Göbel, Kathrin; Reifarth, René; Travaglio, Claudia

    2016-04-01

    Beyond iron, a small fraction of the total abundances in the Solar System is made of proton-rich isotopes, the p-nuclei. The clear understanding of their production is a fundamental challenge for nuclear astrophysics. The p-nuclei constrain the nucleosynthesis in core-collapse and thermonuclear supernovae. The γ-process is the most established scenario for the production of the p-nuclei, which are produced via different photodisintegration paths starting on heavier nuclei. A large effort from nuclear physics is needed to access the relevant nuclear reaction rates far from the valley of stability. This review describes the production of the heavy proton-rich isotopes by the γ-process in stars, and explores the state of the art of experimental nuclear physics to provide nuclear data for stellar nucleosynthesis.

  6. Interaction radii of proton-rich radioactive nuclei at A=60-80

    SciTech Connect

    Lima, G. F.; Lepine-Szily, A.; Lichtenthaler, R.; Villari, A. C. C.; Mittig, W.; Casandjian, J. M.; Lewitowicz, M.; Chartier, M.; Hirata, D.; Angelique, J. C.; Orr, N. A.; Audi, G.; Cunsolo, A.; Foti, A.; Donzeaud, C.; MacCormick, M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Gillibert, A.

    1998-12-21

    The interaction radii of proton-rich, radioactive {sub 31}Ga, {sub 32}Ge, {sub 33}As, {sub 34}Se, {sub 35}Br isotopes were measured using the direct method. The secondary beams were produced using a {sup 78}Kr primary beam of 73 MeV/nucleon in conjunction with SISSI and the SPEG spectrometers at GANIL. Most elements show reduced radii which vary with N, with a minimum around N=36-38. The experimental reduced radii are compared to theoretical values obtained from Glauber reaction cross-section calculations based on Relativistic Mean Field (RMF) nuclear densities.

  7. Direct mass measurements of proton-rich isotopes of Ge, As, Se, and Br

    NASA Astrophysics Data System (ADS)

    Lima, G. F.; Lépine-Szily, A.; Audi, G.; Mittig, W.; Chartier, M.; Orr, N. A.; Lichtenthaler, R.; Angelique, J. C.; Casandjian, J. M.; Cunsolo, A.; Donzaud, C.; Foti, A.; Gillibert, A.; Lewitowicz, M.; Lukyanov, S.; MacCormick, M.; Morrissey, D. J.; Ostrowski, A. N.; Sherrill, B. M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Vieira, D. J.; Villari, A. C.; Wouters, J. M.

    2002-04-01

    The masses of neutron-deficient nuclei close to the proton drip line are an important input for the rapid proton-capture process modeling above 56Ni. The measurement of the masses of proton-rich nuclei with 32<=Z<=35 has been made using a direct time-of-flight technique. The masses of the nuclides 66As,68Se, and 71Br are reported for the first time, with mass excesses of -51 500(680), -53 620(1000), and -57 060(570) keV being found. The masses agree well in most cases with the Audi-Wapstra systematics.

  8. Mass Measurements of Proton-rich Nuclides at the Cooler Storage Ring at IMP

    SciTech Connect

    Zhang, Y. H.; Xu, H. S.; Wang, M.; Zhou, X. H.; Yuan, Y. J.; Xia, J. W.; Hu, Z. G.; Huang, W. X.; Liu, Y.; Ma, X.; Mao, R. S.; Mei, B.; Sun, Z. Y.; Wang, J. S.; Xiao, G. Q.; Yan, X. L.; Yang, J. C.; Zhao, H. W.; Zhao, T. C.; Zhang, X. Y.; and others

    2011-11-30

    Recent results and progress of mass measurements of proton-rich nuclei using isochronous mass spectrometry (IMS) are reported. The nuclei under investigation were produced via fragmentation of relativistic energy heavy ions of {sup 78}Kr and {sup 58}Ni. After in-flight separation by the fragment separator RIBLL-2, the nuclei were injected and stored in the experimental storage ring CSRe, and their masses were determined from measurements of the revolution times. The impact of these measurements on the stellar nucleosynthesis in the rp-process is discussed.

  9. Static and dynamic aspect of covariant density functional theory in proton rich nuclei

    SciTech Connect

    Ring, P.; Lalazissis, G. A.; Paar, N.; Vretenar, D.

    2007-11-30

    Proton rich nuclei are investigated in the framework of Covariant Density Functional Theory (CDFT). The Relativistic Hartree Bogoliubov (RHB) model is used to study the proton drip line in the region of heavy and superheavy nuclei. The dynamical behavior of nuclei with a large proton excess is studied within the Relativistic Quasiparticle Random Phase Approximation (RQRPA). Low lying El-strength is observed and it is shown that it corresponds to an oscillation of the proton skin against the isospin saturated neutron-proton core. This mode is in full analogy to the neutron pygmy resonances found in many nuclei with neutron excess.

  10. Searching for high-K isomers in the proton-rich A ∼ 80 mass region

    NASA Astrophysics Data System (ADS)

    Bai, Zhi-Jun; Jiao, Chang-Feng; Gao, Yuan; Xu, Fu-Rong

    2016-09-01

    Configuration-constrained potential-energy-surface calculations have been performed to investigate the K isomerism in the proton-rich A ∼ 80 mass region. An abundance of high-K states are predicted. These high-K states arise from two and four-quasi-particle excitations, with Kπ = 8+ and Kπ = 16+, respectively. Their excitation energies are comparatively low, making them good candidates for long-lived isomers. Since most nuclei under study are prolate spheroids in their ground states, the oblate shapes of the predicted high-K states may indicate a combination of K isomerism and shape isomerism. Supported by National Key Basic Research Program of China (2013CB834402) and National Natural Science Foundation of China (11235001, 11320101004 and 11575007)

  11. Interaction radii of proton-rich radioactive nuclei at A=60{endash}80

    SciTech Connect

    Lima, G.F.; Lepine-Szily, A.; Villari, A.C.; Lichtenthaler, R.; Villari, A.C.; Mittig, W.; Chartier, M.; Casandjian, J.M.; Lewitowicz, M.; Ostrowski, A.N.; Hirata, D.; Angelique, J.C.; Orr, N.A.; Audi, G.; Cunsolo, A.; Foti, A.; Donzeaud, C.; MacCormick, M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Gillibert, A.; Chartier, M.; Morrissey, D.J.; Sherrill, B.M.; Ostrowski, A.N.; Vieira, D.J.; Wouters, J.M.

    1998-12-01

    The interaction radii of proton-rich, radioactive {sub 31}Ga,thinsp{sub 32}Ge,thinsp{sub 33}As,thinsp{sub 34}Se,thinsp{sub 35}Br isotopes were measured using the direct method. The secondary beams were produced using a {sup 78}Kr primary beam of 73 MeV/nucleon in conjunction with SISSI and the SPEG spectrometers at GANIL. Most elements show reduced radii which vary with N, with a minimum around N=36{endash}38. The experimental reduced radii are compared to theoretical values obtained from Glauber reaction cross-section calculations based on Relativistic Mean Field (RMF) nuclear densities. {copyright} {ital 1998 American Institute of Physics.}

  12. Searching for high-K isomers in the proton-rich A ˜ 80 mass region

    NASA Astrophysics Data System (ADS)

    Bai, Zhi-Jun; Jiao, Chang-Feng; Gao, Yuan; Xu, Fu-Rong

    2016-09-01

    Configuration-constrained potential-energy-surface calculations have been performed to investigate the K isomerism in the proton-rich A ˜ 80 mass region. An abundance of high-K states are predicted. These high-K states arise from two and four-quasi-particle excitations, with Kπ = 8+ and Kπ = 16+, respectively. Their excitation energies are comparatively low, making them good candidates for long-lived isomers. Since most nuclei under study are prolate spheroids in their ground states, the oblate shapes of the predicted high-K states may indicate a combination of K isomerism and shape isomerism. Supported by National Key Basic Research Program of China (2013CB834402) and National Natural Science Foundation of China (11235001, 11320101004 and 11575007)

  13. Schottky Mass Measurements of Cooled Proton-Rich Nuclei at the GSI Experimental Storage Ring

    SciTech Connect

    Radon, T.; Schlitt, B.; Beckert, K.; Bosch, F.; Eickhoff, H.; Franzke, B.; Geissel, H.; Hausmann, M.; Irnich, H.; Klepper, O.; Kluge, H.; Kozhuharov, C.; Kraus, G.; Muenzenberg, G.; Nickel, F.; Nolden, F.; Patyk, Z.; Reich, H.; Scheidenberger, C.; Schwab, W.; Steck, M.; Suemmerer, K.; Kerscher, T.; Beha, T.; Loebner, K.E.; Fujita, Y.; Jung, H.C.; Wollnik, H.; Novikov, Y.

    1997-06-01

    High-precision mass measurements of proton-rich isotopes in the range of 60{le}Z{le}84 were performed using the novel technique of Schottky spectrometry. Projectile fragments produced by {sup 209}Bi ions at 930{ital A} MeV were separated with the magnetic spectrometer FRS and stored and cooled in the experimental storage ring (ESR). A typical mass resolving power of 350000 and a precision of 100keV were achieved in the region A{approx}200 . Masses of members of {alpha} chains linked by precise Q{sub {alpha}} values but not yet connected to the known masses were determined. In this way it is concluded that {sup 201}Fr and {sup 197}At are proton unbound. {copyright} {ital 1997} {ital The American Physical Society}

  14. Very Low Energy Protons From the Beta Decay of Proton Rich Nuclei For Nuclear Astrophysics

    SciTech Connect

    Simmons, E.; Trache, L.; Banu, A.; McCleskey, M.; Roeder, B.; Spiridon, A.; Tribble, R. E.; Saastamoinen, A.; Aysto, J.; Davinson, T.; Woods, P. J.; Lotay, G. J.

    2010-03-01

    We have developed a new experimental technique to measure very low energy protons from beta-delayed p-decay of proton-rich nuclei produced and separated with the MARS recoil spectrometer at TAMU. Recently we have investigated the beta-delayed p-decays of {sup 23}Al and {sup 31}Cl and obtained information on the resonances in the reactions {sup 22}Na(p,gamma){sup 23}Mg and {sup 30}P(p,gamma){sup 31}S, respectively. These reactions are important in explosive H-burning in Novae. A simple setup consisting of a telescope made of a thin double sided Si strip detector (p-detector) backed or sandwiched between two thick Si detectors (beta-detectors) was designed. We studied two different p-detectors and found that the thinner detectors with a small cell size are best to measure proton energies as low as 2-300 keV.

  15. Mass prediction of proton-rich nuclides with the Coulomb displacement energies in the relativistic point-coupling model

    NASA Astrophysics Data System (ADS)

    Sun, BaoHua; Zhao, PengWei; Meng, Jie

    2011-02-01

    The masses, one- and two-proton separation energies of proton-rich nuclei with Z = 20-55, are computed using the measured masses of mirror neutron-rich nuclei and the Coulomb displacement energies calculated from the relativistic point-coupling model. The implications for the proton drip lines, candidates for two-proton emitters, as well as the impact on the astrophysical rp-process are discussed.

  16. Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta

    SciTech Connect

    Hidaka, Hiroshi; Yoneda, Shigekazu E-mail: s-yoneda@kahaku.go.jp

    2014-05-10

    The idea that solar system materials were irradiated by solar cosmic rays from the early Sun has long been suggested, but is still questionable. In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their isotopic abundances of proton-rich nuclei, leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of proton-rich isotopes (p-isotopes), {sup 84}Sr, {sup 130}Ba, {sup 132}Ba, {sup 136}Ce, {sup 138}Ce, and {sup 144}Sm, were observed, particularly in the first chemical separate, which possibly leached out of the very shallow layer within a few μm from the surface of regolith grains in the sample. The results reveal the production of p-isotopes through the interaction of solar cosmic rays with the superficial region of the regolith grains before the formation of the Kapoeta meteorite parent body, suggesting strong activity in the early Sun.

  17. Stability of proton-rich nuclei in the upper {ital sd} shell and lower {ital pf} shell

    SciTech Connect

    Cole, B.J.

    1996-09-01

    The decay properties of proton-rich nuclei with {ital Z}=19{endash}30 are investigated using measured binding energies of the analog neutron-rich nuclei and Coulomb energy shifts deduced from a parametrization of measured Coulomb displacement energies. Predicted binding energies and separation energies are compared where possible with previous calculations; in most cases the calculations agree within the quoted uncertainties. The positions of the one-proton and diproton drip lines are determined from the calculated separation energies. It is suggested that good candidates for the observation of correlated two-proton emission are {sup 34}Ca, {sup 38,39}Ti, {sup 45}Fe, {sup 48}Ni, and {sup 54}Zn. {copyright} {ital 1996 The American Physical Society.}

  18. Pygmy dipole response of proton-rich argon nuclei in random-phase approximation and no-core shell model

    SciTech Connect

    Barbieri, C.; Martinez-Pinedo, G.; Caurier, E.; Langanke, K.

    2008-02-15

    The occurrence of a pygmy dipole resonance in proton rich {sup 32,34}Ar is studied using the unitary correlator operator method interaction V{sub UCOM}, based on Argonne V18. Predictions from the random-phase approximation (RPA) and the shell model in a no-core basis are compared. It is found that the inclusion of configuration mixing up to two-particles-two-holes broadens the pygmy strength slightly and reduces sensibly its strength, as compared to the RPA predictions. For {sup 32}Ar, a clear peak associated with a pygmy resonance is found. For {sup 34}Ar, the pygmy states are obtained close to the giant dipole resonance and mix with it.

  19. High-Temperature Nucleosynthesis Processes on the Proton-Rich Side of Stability: the Alpha-Rich Freezeout and the rp^2-Process

    NASA Astrophysics Data System (ADS)

    Meyer, Bradley S.

    2001-10-01

    Nucleosynthesis on the proton-rich side of stability has at least two intriguing aspects. First, the most abundant of the stable iron-group isotopes, such as ^48Ti, ^52Cr, and ^56,57Fe, are synthesized as proton-rich, radioactive parents in alpha-rich freezeouts from equilibrium. The production of these radioactive progenitors depends in large measure on reactions on the proton-rich side of stability. The second intriguing aspect is that explosive nucleosynthesis in a hydrogen-rich environment (namely, the rp-process) may be associated with exotic astrophysical settings, such as x-ray bursts, and may be responsible for production of some of the light p-process nuclei (for example, ^92,94Mo and ^96,98Ru). We have developed web-based tools to help nuclear physicists determine which nuclear reactions on the proton-rich side of stability govern the nucleosynthesis in these processes. For the alpha-rich freezeout, one may determine the effect of any one of 2,140 reactions on the yield of any isotope in the nuclear reaction network with the web calculator. As a relevant example, I will discuss the governing role of ^57Ni (n,p)^57Co in the synthesis of the important astronomical observable ^57Co. As for explosive, proton-rich burning, I will discuss the synthesis of p-process nuclei in the repetitive rp-process (the rp^2-process). Movies of the rp^2-process illustrate its important features and give some indications of the important nuclear reactions.

  20. Nucleus-nucleus potentials

    SciTech Connect

    Satchler, G.R.

    1983-01-01

    The significance of a nucleus-nucleus potential is discussed. Information about such potentials obtained from scattering experiments is reviewed, including recent examples of so-called rainbow scattering that probe the potential at smaller distances. The evidence for interactions involving the nuclear spins is summarized, and their possible origin in couplings to non-elastic channels. Various models of the potentials are discussed.

  1. Observation of the particle-unstable nucleus 10N

    NASA Astrophysics Data System (ADS)

    Lépine-Szily, A.; Oliveira, J. M.; Vanin, V. R.; Ostrowski, A. N.; Lichtenthäler, R.; di Pietro, A.; Guimarães, V.; Laird, A. M.; Maunoury, L.; Lima, G. F.; de Oliveira Santos, F.; Roussel-Chomaz, P.; Savajols, H.; Trinder, W.; Villari, A. C.; de Vismes, A.

    2002-05-01

    For the first time evidence of the ground state of the proton-rich, unbound nucleus 10N has been found in the multinucleon transfer reaction 10B(14N,14B)10N. The observed resonance of 10N has a mass excess of 38.8(4) MeV and a width of Γ=2.3(16) MeV, close to the Audi-Wapstra estimation of 38.5(4) MeV. 10N is the last missing A=10 multiplet partner.

  2. Neutron-Proton Pairing Effect on One-Proton and Two-Proton Separation Energies in Rare-Earth Proton-Rich Nuclei

    NASA Astrophysics Data System (ADS)

    Hammache, F.; Allal, N. H.; Fellah, M.

    2012-12-01

    The one-proton and two-proton separation energies are studied for "ordinary" and rare-earth proton-rich nuclei by including the isovector neutron-proton (np) pairing correlations using the BCS approximation. Even-even as well as odd nuclei are considered. In the latter case, the wave function is defined using the blocked-level technique. The single-particle energies used are those of a deformed Woods-Saxon mean field. It is shown that the np isovector pairing effects on the one-proton and two-proton separation energies are non-negligible. However, the only isovector BCS approximation seems to be inadequate for a good description of these quantities when including the np pairing effects: either a particle-number projection or the inclusion of the isoscalar pairing effect seems to be necessary. Another possible improvement would be a more realistic choice of the pairing strengths.

  3. Design of an rf separation system for a proton-rich radioisotope beam produced by using an in-flight fragment separator

    NASA Astrophysics Data System (ADS)

    Kim, Myeongjin; Yun, Chong-Cheol; Kim, Jong-Won; Lee, Jaeyu

    2013-03-01

    An in-flight fragment separator is a device to separate a radioisotope (RI) beam of interest produced by bombarding a thin target with a primary heavy-beam usually of high intensity. The isotope beam separation is done by momentum dispersion of dipole magnets and energy loss in a wedge-shaped degrader. However, this separation method is not sufficient for proton-rich isotope beams because their momenta tend to overlap with the low-momentum tails of more abundant fragments produced with larger cross sections. An additional separation technique, which relies on the velocity difference in the isotope beams, can be used to enhance the purity of the desired isotope beam. A separation system based on an rf-kicker was considered, and its beam line was designed using the TRANSPORT and the COSY INFINITY codes. Trajectories and vertical separations of the RI beams were calculated using the LISE++ code. The background isotope beam can be greatly reduced with the use of the rf separator system, but transmission of the isotope beam may be reduced by the aperture of the rf kicker. The lower rf frequency of the primary beam is an important factor in adopting the rf separator system. The electromagnetic design of the rf-kicker was studied.

  4. The masses of proton-rich isotopes of niobium, molybdenum, technetium, ruthenium and rhodium and their influence on the astrophysical rp and vp processes

    NASA Astrophysics Data System (ADS)

    Fallis, Jennifer

    The Canadian Penning Trap mass spectrometer located at Argonne National Laboratory has been built for the purpose of studying the masses of both stable and unstable nuclides. For this thesis 18 proton-rich unstable nuclides of elements Nb, Mo, Tc, Ru and Rh have been measured with this apparatus to an average precision of 7.8 x 10-8. The masses of 6 of these nuclides had not been measured when this thesis was undertaken, and 4 more were not known to the precisions required for use in astrophysical nucleosynthesis models. The masses of these nuclides were of particular interest as the reaction paths of two proposed nucleosynthetic processes, the rp and vp processes, pass through this region. The rp process is thought to occur in X-ray bursts and directly affects the X-ray luminosity which is emitted from these objects. The vp process is thought to occur in the inner regions of the material ejected during a core-collapse supernova explosion and is of particular interest as it may answer some outstanding questions about the origins of the chemical elements in the Universe. The Canadian Penning Trap and associated apparatus were used to determine the masses of 18 nuclides, some for the first time ever. Our measurements improve the precision on all of the masses, by a factor of 70 in some cases. Our results are necessary to determine the proton-separation energies for these nuclides which are critical for determining the paths and reaction rates fro the rp and vp processes. In particular, the effect of our measurements of 92Ru and 93Rh on the expected production ratio of 92Mo to 94Mo in the vp process, and the effect of our measurement of 87Mo on the path of this process will be discussed.

  5. First observation of the unbound nucleus 15Ne.

    PubMed

    Wamers, F; Marganiec, J; Aksouh, F; Aksyutina, Yu; Álvarez-Pol, H; Aumann, T; Beceiro-Novo, S; Boretzky, K; Borge, M J G; Chartier, M; Chatillon, A; Chulkov, L V; Cortina-Gil, D; Emling, H; Ershova, O; Fraile, L M; Fynbo, H O U; Galaviz, D; Geissel, H; Heil, M; Hoffmann, D H H; Johansson, H T; Jonson, B; Karagiannis, C; Kiselev, O A; Kratz, J V; Kulessa, R; Kurz, N; Langer, C; Lantz, M; Le Bleis, T; Lemmon, R; Litvinov, Yu A; Mahata, K; Müntz, C; Nilsson, T; Nociforo, C; Nyman, G; Ott, W; Panin, V; Paschalis, S; Perea, A; Plag, R; Reifarth, R; Richter, A; Rodriguez-Tajes, C; Rossi, D; Riisager, K; Savran, D; Schrieder, G; Simon, H; Stroth, J; Sümmerer, K; Tengblad, O; Weick, H; Wimmer, C; Zhukov, M V

    2014-04-01

    We report on the first observation of the unbound proton-rich nucleus 15Ne. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u 17Ne. The 15Ne ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to 13O with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2- and 1- states in 14F is observed. The 15Ne ground state is shown to have a strong configuration with two protons in the (sd) shell around 13O with a 63(5)% (1s1/2)2 component.

  6. Global optical potential for nucleus-nucleus systems from 50 MeV/u to 400 MeV/u

    NASA Astrophysics Data System (ADS)

    Furumoto, T.; Horiuchi, W.; Takashina, M.; Yamamoto, Y.; Sakuragi, Y.

    2012-04-01

    We present a new global optical potential (GOP) for nucleus-nucleus systems, including neutron-rich and proton-rich isotopes, in the energy range of 50-400 MeV/u. The GOP is derived from the microscopic folding model with the complex G-matrix interaction CEG07 and the global density presented by the São Paulo group. The folding model accounts for realistic complex optical potentials of nucleus-nucleus systems well and reproduces the existing elastic scattering data for stable heavy-ion projectiles at incident energies above 50 MeV/u. We then calculate the folding-model potentials (FMPs) for projectiles of even-even isotopes, 8-22C, 12-24O, 16-38Ne, 20-40Mg, 22-48Si, 26-52S, 30-62Ar, and 34-70Ca, scattered by stable target nuclei of 12C, 16O, 28Si, 40Ca 58Ni, 90Zr, 120Sn, and 208Pb at incident energies of 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 250, 300, 350, and 400 MeV/u. The calculated FMP is represented, with a sufficient accuracy, by a linear combination of 10-range Gaussian functions. The expansion coefficients depend on the incident energy, the projectile and target mass numbers, and the projectile atomic number, while the range parameters depend only on the projectile and target mass numbers. The adequate mass region of the present GOP by the global density is inspected in comparison with FMP by realistic density. The full set of the range parameters and the coefficients for all the projectile-target combinations at each incident energy are provided on a permanent open-access website together with a fortran program for calculating the microscopic-basis GOP (MGOP) for a desired projectile nucleus by the spline interpolation over the incident energy and the target mass number.

  7. Proton-rich nucleosynthesis and nuclear physics

    SciTech Connect

    Rauscher, T.; Froehlich, C.

    2012-11-12

    Although the detailed conditions for explosive nucleosynthesis are derived from astrophysical modeling, nuclear physics determines fundamental patterns in abundance yields, not only for equilibrium processes. Focussing on the {nu}p- and the {gamma}-process, general nucleosynthesis features within the range of astrophysical models, but (mostly) independent of details in the modelling, are presented. Remaining uncertainties due to uncertain Q-values and reaction rates are discussed.

  8. Identification of highly deformed even-even nuclei in the neutron- and proton-rich regions of the nuclear chart from the B(E2)↑ and E2 predictions in the generalized differential equation model

    NASA Astrophysics Data System (ADS)

    Nayak, R. C.; Pattnaik, S.

    2015-11-01

    We identify here the possible occurrence of large deformations in the neutron- and proton-rich (n-rich and p-rich) regions of the nuclear chart from extensive predictions of the values of the reduced quadrupole transition probability B(E2)↑ for the transition from the ground state to the first 2+ state and the corresponding excitation energy E2 of even-even nuclei in the recently developed generalized differential equation (GDE) model exclusively meant for these physical quantities. This is made possible from our analysis of the predicted values of these two physical quantities and the corresponding deformation parameters derived from them such as the quadrupole deformation β2, the ratio of β2 to the Weisskopf single-particle β2(sp) and the intrinsic electric quadrupole moment Q0, calculated for a large number of both known as well as hitherto unknown even-even isotopes of oxygen to fermium (0 to FM; Z = 8-100). Our critical analysis of the resulting data convincingly support possible existence of large collectivity for the nuclides 30,32Ne,34Mg, 60Ti, 42,62,64Cr,50,68Fe, 52,72Ni, 72,70,96Kr,74,76Sr,78,80,106,108Zr, 82,84,110,112Mo, 140Te,144Xe, 148Ba,122Ce, 128,156Nd,130,132,158,160Sm and 138,162,164,166Gd, whose values of β2 are found to exceed 0.3 and even 0.4 in some cases. Our findings of large deformations in the exotic n-rich regions support the existence of another “island of inversion” in the heavy-mass region possibly caused by breaking of the N = 70 subshell closure.

  9. The Nucleus Introduced

    PubMed Central

    Pederson, Thoru

    2011-01-01

    Now is an opportune moment to address the confluence of cell biological form and function that is the nucleus. Its arrival is especially timely because the recognition that the nucleus is extremely dynamic has now been solidly established as a paradigm shift over the past two decades, and also because we now see on the horizon numerous ways in which organization itself, including gene location and possibly self-organizing bodies, underlies nuclear functions. PMID:20660024

  10. Kaon-nucleus scattering

    NASA Technical Reports Server (NTRS)

    Hong, Byungsik; Buck, Warren W.; Maung, Khin M.

    1989-01-01

    Two kinds of number density distributions of the nucleus, harmonic well and Woods-Saxon models, are used with the t-matrix that is taken from the scattering experiments to find a simple optical potential. The parameterized two body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to imaginary part of the forward elastic scattering amplitude, are shown. The eikonal approximation was chosen as the solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

  11. Kaon-nucleus scattering

    NASA Technical Reports Server (NTRS)

    Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.

    1989-01-01

    The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

  12. Convergence of the nucleus-nucleus Glauber multiple scattering series

    SciTech Connect

    Usmani, A.A.; Ahmad, I. )

    1991-05-01

    The Glauber {ital S}-matrix operator for nucleus-nucleus scattering is expressed as a finite series of matrix elements involving Bell's polynomials. Analyzing {alpha}{sup 4}He elastic-scattering data at the incident momentum of 4.32 GeV/{ital c}, we infer that our expansion is appreciably converging. Further, by applying closure over target and projectile states and neglecting a certain class of terms involving intermediate excitations, we arrive at a recurrence relation for nucleus-nucleus multiple scattering series terms, which invites further study as it seems to provide a simple method for calculating the nucleus-nucleus elastic-scattering cross section.

  13. Onset of deconfinement in nucleus-nucleus collisions

    SciTech Connect

    Gazdzicki, M.; Gorenstein, M. I.; Seyboth, P.

    2012-05-15

    The energy dependence of hadron production in relativistic nucleus-nucleus collisions reveals anomalies-the kink, horn, and step. They were predicted as signals of the deconfinement phase transition and observed by the NA49 Collaboration in central PbPb collisions at the CERN SPS. This indicates the onset of the deconfinement in nucleus-nucleus collisions at about 30 A GeV.

  14. Proton Nucleus Elastic Scattering Data.

    1993-08-18

    Version 00 The Proton Nucleus Elastic Scattering Data file PNESD contains the numerical data and the related bibliography for the differential elastic cross sections, polarization and integral nonelastic cross sections for elastic proton-nucleus scattering.

  15. SUMOrganization of the nucleus.

    PubMed

    Heun, Patrick

    2007-06-01

    In the eukaryotic nucleus, gene expression and maintenance of genome integrity are tightly controlled at multiple levels, from the molecular details to the higher-order structure of the genome. The nucleus contains spatially and functionally distinct compartments in which these fundamental processes are carried out. While the dynamics and functions of some nuclear subdomains, like the nucleolus, have been well studied, other domains, like the PML-nuclear bodies, remain enigmatic. Recent evidence has now implicated the SUMOylation pathway as an important player in subnuclear architecture, particularly in the assembly of PML-nuclear bodies. Related functions include the organization of chromatin loops and maintenance of rDNA repeat stability. Consequently, complete loss of SUMO modification profoundly affects nuclear organization and cell viability.

  16. Antinucleon-nucleus interactions

    SciTech Connect

    Dover, C.B.

    1987-01-01

    Recent experimental and theoretical results on anti p-nucleus interactions are reviewed. We focus on determinations of the anti p optical potential from elastic scattering, the use of (anti p, anti p') inelastic scattering to reveal aspects of the spin-isospin dependence of N anti N amplitudes, and some puzzling features of (anti p, anti n) charge exchange reactions on nuclei. 47 refs., 7 figs.

  17. Analytic optical potentials for nucleon-nucleus nucleus-nucleus collisions involving light and medium nuclei

    NASA Technical Reports Server (NTRS)

    Bidasaria, H. B.; Townsend, L. W.

    1982-01-01

    Utilizing an optical model potential approximation to the exact nucleus-nucleus multiple-scattering series, optical potentials for nucleon-nucleus and nucleus-nucleus collisions are analytically derived. These expressions are applicable to light and medium cosmic ray nuclei as their single-particle density distributions are analytically determined, without approximation, from their actual harmonic well charge density distributions. Pauli correlation effects are included through the use of a simple Gaussian function to replace the usual expression obtained in the infinite nuclear matter approximation.

  18. Neutrino-nucleus interactions

    SciTech Connect

    Gallagher, H.; Garvey, G.; Zeller, G.P.; /Fermilab

    2011-01-01

    The study of neutrino oscillations has necessitated a new generation of neutrino experiments that are exploring neutrino-nuclear scattering processes. We focus in particular on charged-current quasi-elastic scattering, a particularly important channel that has been extensively investigated both in the bubble-chamber era and by current experiments. Recent results have led to theoretical reexamination of this process. We review the standard picture of quasi-elastic scattering as developed in electron scattering, review and discuss experimental results, and discuss additional nuclear effects such as exchange currents and short-range correlations that may play a significant role in neutrino-nucleus scattering.

  19. Nucleus from string theory

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Morita, Takeshi

    2011-08-01

    In generic holographic QCD, we find that baryons are bound to form a nucleus, and that its radius obeys the empirically-known mass-number (A) dependence r∝A1/3 for large A. Our result is robust, since we use only a generic property of D-brane actions in string theory. We also show that nucleons are bound completely in a finite volume. Furthermore, employing a concrete holographic model (derived by Hashimoto, Iizuka, and Yi, describing a multibaryon system in the Sakai-Sugimoto model), the nuclear radius is evaluated as O(1)×A1/3[fm], which is consistent with experiments.

  20. Higgs-boson production in nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W. (Principal Investigator)

    1990-01-01

    Cross-section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two-photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two-photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  1. Higgs-Boson Production in Nucleus-Nucleus Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Cross section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  2. Meson multiplicity versus energy in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Atwater, T. W.; Freier, P. S.

    1986-01-01

    A systematic study of meson multiplicity as a function of energy at energies up to 100 GeV/u in nucleus-nucleus collisions has been made, using cosmic-ray data in nuclear emulsion. The data are consistent with simple nucleon-nucleon superposition models. Multiplicity per interacting nucleon in AA collisions does not appear to differ significantly from pp collisions.

  3. Scaling phenomenon in relativistic nucleus-nucleus collisions

    SciTech Connect

    Wong, C. Y.; Blankenbecler, R.

    1980-01-01

    New scaling variables for proton and pion production in relativistic nucleus-nucleus collisions are introduced which are the generalizations of the Feynmann scaling variable. They allow a simple description of the cross sections at forward and backward angles. 2 figures.

  4. Mechanics of the nucleus.

    PubMed

    Lammerding, Jan

    2011-04-01

    The nucleus is the distinguishing feature of eukaryotic cells. Until recently, it was often considered simply as a unique compartment containing the genetic information of the cell and associated machinery, without much attention to its structure and mechanical properties. This article provides compelling examples that illustrate how specific nuclear structures are associated with important cellular functions, and how defects in nuclear mechanics can cause a multitude of human diseases. During differentiation, embryonic stem cells modify their nuclear envelope composition and chromatin structure, resulting in stiffer nuclei that reflect decreased transcriptional plasticity. In contrast, neutrophils have evolved characteristic lobulated nuclei that increase their physical plasticity, enabling passage through narrow tissue spaces in their response to inflammation. Research on diverse cell types further demonstrates how induced nuclear deformations during cellular compression or stretch can modulate cellular function. Pathological examples of disturbed nuclear mechanics include the many diseases caused by mutations in the nuclear envelope proteins lamin A/C and associated proteins, as well as cancer cells that are often characterized by abnormal nuclear morphology. In this article, we will focus on determining the functional relationship between nuclear mechanics and cellular (dys-)function, describing the molecular changes associated with physiological and pathological examples, the resulting defects in nuclear mechanics, and the effects on cellular function. New insights into the close relationship between nuclear mechanics and cellular organization and function will yield a better understanding of normal biology and will offer new clues into therapeutic approaches to the various diseases associated with defective nuclear mechanics.

  5. Hyperon-nucleus potentials

    NASA Astrophysics Data System (ADS)

    Dover, C. B.; Gal, A.

    We review models for the interaction of baryons ( N, Λ, Σ and Ξ) with nuclei, emphasizing the underlying meson exchange picture. Starting from a phenomenological one boson exchange model (the Nijmegen potential, as an example) which accounts for the available NN, ΛN and ΣN two-body scattering data, we show how to construct the effective baryon-nucleon interaction ( G-matrix). Employing the folding model, we then obtain the many-body potentials for bound states in terms of the nuclear density and the appropriate spin-isospin weighted G-matrices. The models we emphasize most impose SU(3) constraints on baryon-baryon coupling constants SU(3) is broken through the use of physical masses), although we also compare with rough estimates based on quark model relations between coupling constants. We stress the essential unity and economy of such models, in which nucleon and hyperon-nucleus potentials are intimately related via SU(3), and the connection between the two-body and many-body potentials is preserved. We decompose the nuclear potentials into central and spin-orbit parts, each of which is isospin dependent. For nucleons, the microscopic origin of the isospin dependent Lane potential V1 N is clarified. For Λ and Σ hyperons, the one boson exchange model with SU(3) constraints leads to one-body spin-orbit strengths VLSB which are relatively weak ( VLSΛ ≈ 1.5-2 MeV, VLSΣ ≈ 2.5-;3 MeV, compared to VLSN ≈ 7-9 MeV). We demonstrate the interplay between symmetric and antisymmetric two-body spin-orbit forces which give rise to these results, as well as the special role of K and K ∗ exchange for hyperons. We contrast these results with predictions based on the naive quark model. From S and P-wave two-body interactions, a Lane potential for the Σ of depth V1 Σ ≈ 50-60 MeV is predicted although this result is somewhat uncertain. For the Ξ, the nuclear potential is very different in various models for the two-body interaction based on SU(3) or the quark

  6. Unexpected doubly-magic nucleus.

    SciTech Connect

    Janssens, R. V. F.; Physics

    2009-01-01

    Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope {sup 24}O has been found to be one such nucleus - yet it lies just at the limit of stability.

  7. Sensitivity of cross sections for elastic nucleus-nucleus scattering to halo nucleus density distributions

    SciTech Connect

    Alkhazov, G. D.; Sarantsev, V. V.

    2012-12-15

    In order to clear up the sensitivity of the nucleus-nucleus scattering to the nuclear matter distributions in exotic halo nuclei, we have calculated differential cross sections for elastic scattering of the {sup 6}He and {sup 11}Li nuclei on several nuclear targets at the energy of 0.8 GeV/nucleon with different assumed nuclear density distributions in {sup 6}He and {sup 11}Li.

  8. Cometary nucleus and active regions

    NASA Technical Reports Server (NTRS)

    Whipple, F. L.

    1984-01-01

    On the basis of the icy conglomerate model of cometary nuclei, various observations demonstrate the spotted nature of many or most nuclei, i.e., regions of unusual activity, either high or low. Rotation periods, spin axes and even precession of the axes are determined. The observational evidence for variations in activity over the surfaces of cometary nuclei are listed and discussed. On June 11 the comet IRAS-ARAKI-ALCOCK approached the Earth to a distance of 0.031 AU, the nearest since C/Lexell, 1770 I, providing a unique opportunity for near-nucleus observations. Preliminary analysis of these images establishes the spin axis of the nucleus, with an oblioquity to the orbit plane of approximately 50 deg, and a lag angle of sublimation approximately 35 deg from the solar meridian on the nucleus. Asymmetries of the inner coma suggests a crazy-quilt distribution of ices with differing volatility over the surface of the nucleus. The observations of Comet P/Homes 1892 III, exhibiting two 8-10 magnitude bursts, are carefully analyzed. The grazing encounter produced, besides the first great burst, an active area on the nucleus, which was rotating retrograde with a period of 16.3hr and inclination nearly 180 deg. After the first burst the total magnitude fell less than two magnitudes from November 7 to November 30 (barely naked eye) while the nuclear region remained diffuse or complex, rarely if ever showing a stellar appearance. The fading was much more rapid after the second burst. The grazing encounter distributed a volume of large chunks in the neighborhood of the nucleus, maintaining activity for weeks.

  9. Formin' actin in the nucleus.

    PubMed

    Baarlink, Christian; Grosse, Robert

    2014-01-01

    Many if not most proteins can, under certain conditions, change cellular compartments, such as, for example, shuttling from the cytoplasm to the nucleus. Thus, many proteins may exert functions in various and very different subcellular locations, depending on the signaling context. A large amount of actin regulatory proteins has been detected in the mammalian cell nucleus, although their potential roles are much debated and are just beginning to emerge. Recently, members of the formin family of actin nucleators were also reported to dynamically localize to the nuclear environment. Here we discuss our findings that specific diaphanous-related formins can promote nuclear actin assembly in a signal-dependent manner.

  10. Functionalized active-nucleus complex sensor

    DOEpatents

    Pines, Alexander; Wemmer, David E.; Spence, Megan; Rubin, Seth

    2003-11-25

    A functionalized active-nucleus complex sensor that selectively associates with one or more target species, and a method for assaying and screening for one or a plurality of target species utilizing one or a plurality of functionalized active-nucleus complexes with at least two of the functionalized active-nucleus complexes having an attraction affinity to different corresponding target species. The functionalized active-nucleus complex has an active-nucleus and a targeting carrier. The method involves functionalizing an active-nucleus, for each functionalized active-nucleus complex, by incorporating the active-nucleus into a macromolucular or molecular complex that is capable of binding one of the target species and then bringing the macromolecular or molecular complexes into contact with the target species and detecting the occurrence of or change in a nuclear magnetic resonance signal from each of the active-nuclei in each of the functionalized active-nucleus complexes.

  11. Higgs and Particle Production in Nucleus-Nucleus Collisions

    NASA Astrophysics Data System (ADS)

    Liu, Zhe

    We apply a diagrammatic approach to study Higgs boson, a color-neutral heavy particle, pro- duction in nucleus-nucleus collisions in the saturation framework without quantum evolution. We assume the strong coupling constant much smaller than one. Due to the heavy mass and colorless nature of Higgs particle, final state interactions are absent in our calculation. In order to treat the two nuclei dynamically symmetric, we use the Coulomb gauge which gives the appropriate light cone gauge for each nucleus. To further eliminate initial state interactions we choose specific prescriptions in the light cone propagators. We start the calculation from only two nucleons in each nucleus and then demonstrate how to generalize the calculation to higher orders diagrammatically. We simplify the diagrams by the Slavnov-Taylor-Ward identities. The resulting cross section is factorized into a product of two Weizsacker-Williams gluon distributions of the two nuclei when the transverse momentum of the produced scalar particle is around the saturation momentum. To our knowledge this is the first process where an exact analytic formula has been formed for a physical process, involving momenta on the order of the saturation momentum, in nucleus-nucleus collisions in the quasi-classical approximation. Since we have performed the calculation in an unconventional gauge choice, we further confirm our results in Feynman gauge where the Weizsacker-Williams gluon distribution is interpreted as a transverse momentum broadening of a hard gluons traversing a nuclear medium. The transverse momentum factorization manifests itself in light cone gauge but not so clearly in Feynman gauge. In saturation physics there are two different unintegrated gluon distributions usually encountered in the literature: the Weizsacker-Williams gluon distribution and the dipole gluon distribution. The first gluon distribution is constructed by solving classical Yang-Mills equation of motion in the Mc

  12. Analysis of relativistic nucleus-nucleus interactions in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1987-01-01

    The development of a computer-assisted method is reported for the determination of the angular distribution data for secondary particles produced in relativistic nucleus-nucleus collisions in emulsions. The method is applied to emulsion detectors that were placed in a constant, uniform magnetic field and exposed to beams of 60 and 200 GeV/nucleon O-16 ions at the Super Proton Synchrotron (SPS) of the European Center for Nuclear Research (CERN). Linear regression analysis is used to determine the azimuthal and polar emission angles from measured track coordinate data. The software, written in BASIC, is designed to be machine independent, and adaptable to an automated system for acquiring the track coordinates. The fitting algorithm is deterministic, and takes into account the experimental uncertainty in the measured points. Further, a procedure for using the track data to estimate the linear momenta of the charged particles observed in the detectors is included.

  13. Dynamical nucleus-nucleus potential at short distances

    SciTech Connect

    Jiang Yongying; Wang Ning; Li Zhuxia; Scheid, Werner

    2010-04-15

    The dynamical nucleus-nucleus potentials for fusion reactions {sup 40}Ca+{sup 40}Ca, {sup 48}Ca+{sup 208}Pb, and {sup 126}Sn+{sup 130}Te are studied with the improved quantum molecular dynamics model together with the extended Thomas-Fermi approximation for the kinetic energies of nuclei. The obtained fusion barrier for {sup 40}Ca+{sup 40}Ca is in good agreement with the extracted fusion barrier from the measured fusion excitation function, and the depths of the fusion pockets are close to the results of time-dependent Hartree-Fock calculations. The energy dependence of the fusion barrier is also investigated. The fusion pocket becomes shallow for a heavy fusion system and almost disappears for heavy nearly symmetric systems, and the obtained potential at short distances is higher than the adiabatic potential.

  14. Azimuthal correlation and collective behavior in nucleus-nucleus collisions

    SciTech Connect

    Mali, P.; Mukhopadhyay, A. Sarkar, S.; Singh, G.

    2015-03-15

    Various flow effects of nuclear and hadronic origin are investigated in nucleus-nucleus collisions. Nuclear emulsion data collected from {sup 84}Kr + Ag/Br interaction at an incident energy of 1.52 GeV per nucleon and from {sup 28}Si + Ag/Br interaction at an incident energy of 14.5 GeV per nucleon are used in the investigation. The transverse momentum distribution and the flow angle analysis show that collective behavior, like a bounce-off effect of the projectile spectators and a sidesplash effect of the target spectators, are present in our event samples. From an azimuthal angle analysis of the data we also see a direct flow of the projectile fragments and of the produced charged particles. On the other hand, for both data samples the target fragments exhibit a reverse flow, while the projectile fragments exhibit an elliptic flow. Relevant flow parameters are measured.

  15. Single nucleon emission in relativistic nucleus-nucleus reactions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Townsend, Lawrence W.

    1992-01-01

    Significant discrepancies between theory and experiment have previously been noted for nucleon emission via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work investigates the hypothesis that these discrepancies have arisen due to uncertainties about how to deduce the experimental electromagnetic cross section from the total measured cross section. An optical-model calculation of single neutron removal is added to electromagnetic cross sections and compared to the total experimental cross sections. Good agreement is found thereby resolving some of the earlier noted discrepancies. A detailed comparison to the recent work of Benesh, Cook, and Vary is made for both the impact parameter and the nuclear cross section. Good agreement is obtained giving an independent confirmation of the parameterized formulas developed by those authors.

  16. Hummingbird Comet Nucleus Analysis Mission

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel; Carle, Glenn C.; Lasher, Larry E.

    2000-01-01

    Hummingbird is a highly focused scientific mission, proposed to NASA s Discovery Program, designed to address the highest priority questions in cometary science-that of the chemical composition of the cometary nucleus. After rendezvous with the comet, Hummingbird would first methodically image and map the comet, then collect and analyze dust, ice and gases from the cometary atmosphere to enrich characterization of the comet and support landing site selection. Then, like its namesake, Hummingbird would carefully descend to a pre-selected surface site obtaining a high-resolution image, gather a surface material sample, acquire surface temperature and then immediately return to orbit for detailed chemical and elemental analyses followed by a high resolution post-sampling image of the site. Hummingbird s analytical laboratory contains instrumentation for a comprehensive molecular and elemental analysis of the cometary nucleus as well as an innovative surface sample acquisition device.

  17. Photoproduction of lepton pairs in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies

    SciTech Connect

    Moreira, B. D.; Goncalves, V. P.; De Santana Amaral, J. T.

    2013-03-25

    In this contribution we study coherent interactions as a probe of the nonlinear effects in the Quantum Electrodynamics (QED). In particular, we study the multiphoton effects in the production of leptons pairs for proton-nucleus and nucleus-nucleus collisions for heavy nuclei. In the proton-nucleus we assume the ultrarelativistic proton as a source of photons and estimate the photoproduction of lepton pairs on nuclei at RHIC and LHC energies considering the multiphoton effects associated to multiple rescattering of the projectile photon on the proton of the nucleus. In nucleus - nucleus colllisions we consider the two nuclei as a source of photons. As each scattering contributes with a factor {alpha}Z to the cross section, this contribution must be taken into account for heavy nuclei. We consider the Coulomb corrections to calculate themultiple scatterings and estimate the total cross section for muon and tau pair production in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies.

  18. Turbulent mixing condensation nucleus counter

    NASA Astrophysics Data System (ADS)

    Mavliev, Rashid

    The construction and operating principles of the Turbulent Mixing Condensation Nucleus Counter (TM CNC) are described. Estimations based on the semiempirical theory of turbulent jets and the classical theory of nucleation and growth show the possibility of detecting particles as small as 2.5 nm without the interference of homogeneous nucleation. This conclusion was confirmed experimentally during the International Workshop on Intercomparison of Condensation Nuclei and Aerosol Particle Counters (Vienna, Austria). Number concentration, measured by the Turbulent Mixing CNC and other participating instruments, is found to be essentially equal.

  19. Beta Decay Study of the T{sub z}=−2{sup 56}Zn Nucleus and the Determination of the Half-Lives of a Few fp-shell Nuclei

    SciTech Connect

    Rubio, B.; Orrigo, S.E.A.; Kucuk, L.; Montaner-Pizá, A.; Fujita, Y.; Fujita, H.; Blank, B.; Adachi, T.; Agramunt, J.; Algora, A.; Ascher, P.; Cáceres, L.; France, G. de; Gerbaux, M.; Giovinazzo, J.; Grevy, S. [CENBG, Université Bordeaux 1, UMR 5797 CNRS and others

    2014-06-15

    This paper concerns the experimental study of the β decay properties of few proton-rich fp-shell nuclei. The nuclei were produced at GANIL in fragmentation reactions, separated with the LISE spectrometer and stopped in an implantation detector surrounded by Ge detectors. The β-delayed gammas, β-delayed protons and the exotic β-delayed gamma-proton emission have been studied. Preliminary results are presented. The decay of the T{sub z}=−2 nucleus {sup 56}Zn has been studied in detail. Information from the β-delayed protons and β-delayed gammas has been used to deduce the decay scheme. The exotic beta-delayed gamma-proton decay has been observed for the first time in the fp-shell. The interpretation of the data was made possible thanks to the detailed knowledge of the mirror Charge Exchange (CE) process and the gamma de-excitation of the states in {sup 56}Co, the mirror nucleus of {sup 56}Cu.

  20. Comet nucleus sample return mission

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.

  1. Theoretical antideuteron-nucleus absorptive cross sections

    NASA Technical Reports Server (NTRS)

    Buck, W. W.; Norbury, J. W.; Townsend, L. W.; Wilson, J. W.

    1993-01-01

    Antideuteron-nucleus absorptive cross sections for intermediate to high energies are calculated using an ion-ion optical model. Good agreement with experiment (within 15 percent) is obtained in this same model for (bar p)-nucleus cross sections at laboratory energies up to 15 GeV. We describe a technique for estimating antinucleus-nucleus cross sections from NN data and suggest that further cosmic ray studies to search for antideuterons and other antinuclei be undertaken.

  2. Actomyosin contractility rotates the cell nucleus.

    PubMed

    Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G V

    2014-01-21

    The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells.

  3. Actomyosin contractility rotates the cell nucleus

    PubMed Central

    Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G. V.

    2014-01-01

    The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells. PMID:24445418

  4. The multifunctional lateral geniculate nucleus.

    PubMed

    Weyand, Theodore G

    2016-02-01

    Providing the critical link between the retina and visual cortex, the well-studied lateral geniculate nucleus (LGN) has stood out as a structure in search of a function exceeding the mundane 'relay'. For many mammals, it is structurally impressive: Exquisite lamination, sophisticated microcircuits, and blending of multiple inputs suggest some fundamental transform. This impression is bolstered by the fact that numerically, the retina accounts for a small fraction of its input. Despite such promise, the extent to which an LGN neuron separates itself from its retinal brethren has proven difficult to appreciate. Here, I argue that whereas retinogeniculate coupling is strong, what occurs in the LGN is judicious pruning of a retinal drive by nonretinal inputs. These nonretinal inputs reshape a receptive field that under the right conditions departs significantly from its retinal drive, even if transiently. I first review design features of the LGN and follow with evidence for 10 putative functions. Only two of these tend to surface in textbooks: parsing retinal axons by eye and functional group and gating by state. Among the remaining putative functions, implementation of the principle of graceful degradation and temporal decorrelation are at least as interesting but much less promoted. The retina solves formidable problems imposed by physics to yield multiple efficient and sensitive representations of the world. The LGN applies context, increasing content, and gates several of these representations. Even if the basic concentric receptive field remains, information transmitted for each LGN spike relative to each retinal spike is measurably increased. PMID:26479339

  5. Music and the nucleus accumbens.

    PubMed

    Mavridis, Ioannis N

    2015-03-01

    Music is a universal feature of human societies over time, mainly because it allows expression and regulation of strong emotions, thus influencing moods and evoking pleasure. The nucleus accumbens (NA), the most important pleasure center of the human brain (dominates the reward system), is the 'king of neurosciences' and dopamine (DA) can be rightfully considered as its 'crown' due to the fundamental role that this neurotransmitter plays in the brain's reward system. Purpose of this article was to review the existing literature regarding the relation between music and the NA. Studies have shown that reward value for music can be coded by activity levels in the NA, whose functional connectivity with auditory and frontal areas increases as a function of increasing musical reward. Listening to music strongly modulates activity in a network of mesolimbic structures involved in reward processing including the NA. The functional connectivity between brain regions mediating reward, autonomic and cognitive processing provides insight into understanding why listening to music is one of the most rewarding and pleasurable human experiences. Musical stimuli can significantly increase extracellular DA levels in the NA. NA DA and serotonin were found significantly higher in animals exposed to music. Finally, passive listening to unfamiliar although liked music showed activations in the NA.

  6. Nucleus accumbens stimulation in pathological obesity.

    PubMed

    Harat, Marek; Rudaś, Marcin; Zieliński, Piotr; Birska, Julita; Sokal, Paweł

    2016-01-01

    One of the potential treatment methods of obesity is deep brain stimulation (DBS) of nucleus accumbens. We describe the case of 19 years old woman with hypothalamic obesity. She weighted 151.4 kg before DBS and the non-surgical methods proved to be inefficient. She was treated with implantation of DBS electrode to nucleus accumbens bilaterally. Results were measured with body mass index and neuropsychological tests. Follow-up was 14 months. Fourteen months after surgery weight was 138 kg, BMI was 48.3. Neuropsychological test results were intact. The presented case supports the thesis of treatment of obesity with nucleus accumbens stimulation. PMID:27154450

  7. Dynamic risk control by human nucleus accumbens

    PubMed Central

    Lopez-Sosa, Fernando; Gonzalez-Rosa, Javier Jesus; Galarza, Ana; Avecillas, Josue; Pineda-Pardo, Jose Angel; Lopez-Ibor, Juan José; Reneses, Blanca; Barcia, Juan Antonio

    2015-01-01

    Real-world decisions about reward often involve a complex counterbalance of risk and value. Although the nucleus accumbens has been implicated in the underlying neural substrate, its criticality to human behaviour remains an open question, best addressed with interventional methodology that probes the behavioural consequences of focal neural modulation. Combining a psychometric index of risky decision-making with transient electrical modulation of the nucleus accumbens, here we reveal profound, highly dynamic alteration of the relation between probability of reward and choice during therapeutic deep brain stimulation in four patients with treatment-resistant psychiatric disease. Short-lived phasic electrical stimulation of the region of the nucleus accumbens dynamically altered risk behaviour, transiently shifting the psychometric function towards more risky decisions only for the duration of stimulation. A critical, on-line role of human nucleus accumbens in dynamic risk control is thereby established. PMID:26428667

  8. Microtubules move the nucleus to quiescence.

    PubMed

    Laporte, Damien; Sagot, Isabelle

    2014-01-01

    The nucleus is a cellular compartment that hosts several macro-molecular machines displaying a highly complex spatial organization. This tight architectural orchestration determines not only DNA replication and repair but also regulates gene expression. In budding yeast microtubules play a key role in structuring the nucleus since they condition the Rabl arrangement in G1 and chromosome partitioning during mitosis through their attachment to centromeres via the kinetochore proteins. Recently, we have shown that upon quiescence entry, intranuclear microtubules emanating from the spindle pole body elongate to form a highly stable bundle that spans the entire nucleus. Here, we examine some molecular mechanisms that may underlie the formation of this structure. As the intranuclear microtubule bundle causes a profound re-organization of the yeast nucleus and is required for cell survival during quiescence, we discuss the possibility that the assembly of such a structure participates in quiescence establishment.

  9. Order and disorder in the nucleus.

    PubMed

    Marshall, Wallace F

    2002-03-01

    Fluorescence in situ hybridization combined with three-dimensional microscopy has shown that chromosomes are not randomly strewn throughout the nucleus but are in fact fairly well organized, with different loci reproducibly found in different regions of the nucleus. At the same time, increasingly sophisticated methods to track and analyze the movements of specific chromosomal loci in vivo using four-dimensional microscopy have revealed that chromatin undergoes extensive Brownian motion. However, the diffusion of interphase chromatin is constrained, implying that chromosomes are physically anchored within the nucleus. This constraint on diffusion is the result of interactions between chromatin and structural elements within the nucleus, such as nuclear pores or the nuclear lamina. The combination of defined positioning with constrained diffusion has a strong impact on interactions between chromosomal loci, and appears to explain the tendency of certain chromosome rearrangements to occur during the development of cancer.

  10. Dynamic risk control by human nucleus accumbens.

    PubMed

    Nachev, Parashkev; Lopez-Sosa, Fernando; Gonzalez-Rosa, Javier Jesus; Galarza, Ana; Avecillas, Josue; Pineda-Pardo, Jose Angel; Lopez-Ibor, Juan José; Reneses, Blanca; Barcia, Juan Antonio; Strange, Bryan

    2015-12-01

    Real-world decisions about reward often involve a complex counterbalance of risk and value. Although the nucleus accumbens has been implicated in the underlying neural substrate, its criticality to human behaviour remains an open question, best addressed with interventional methodology that probes the behavioural consequences of focal neural modulation. Combining a psychometric index of risky decision-making with transient electrical modulation of the nucleus accumbens, here we reveal profound, highly dynamic alteration of the relation between probability of reward and choice during therapeutic deep brain stimulation in four patients with treatment-resistant psychiatric disease. Short-lived phasic electrical stimulation of the region of the nucleus accumbens dynamically altered risk behaviour, transiently shifting the psychometric function towards more risky decisions only for the duration of stimulation. A critical, on-line role of human nucleus accumbens in dynamic risk control is thereby established. PMID:26428667

  11. Comet encke: radar detection of nucleus.

    PubMed

    Kamoun, P G; Campbell, D B; Ostro, S J; Pettengill, G H; Shapiro, I I

    1982-04-16

    The nucleus of the periodic comet Encke was detected in November 1980 with the Arecibo Observatory's radar system (wavelength, 12.6 centimeters). The echoes in the one sense of circular polarization received imply a radar cross section of 1.1 +/- 0.7 square kilometers. The estimated bandwidth of these echoes combined with an estimate of the rotation vector of Encke yields a radius for the nucleus of l.5(+2.3)(-1.0) kilometers. The uncertainties given are dependent primarily on the range of models considered for the comet and for the manner in which its nucleus backscatters radio waves. Should this range prove inadequate, the true value of the radius of the nucleus might lie outside the limits given.

  12. Volumes of cochlear nucleus regions in rodents.

    PubMed

    Godfrey, Donald A; Lee, Augustine C; Hamilton, Walter D; Benjamin, Louis C; Vishwanath, Shilpa; Simo, Hermann; Godfrey, Lynn M; Mustapha, Abdurrahman I A A; Heffner, Rickye S

    2016-09-01

    The cochlear nucleus receives all the coded information about sound from the cochlea and is the source of auditory information for the rest of the central auditory system. As such, it is a critical auditory nucleus. The sizes of the cochlear nucleus as a whole and its three major subdivisions - anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), and dorsal cochlear nucleus (DCN) - have been measured in a large number of mammals, but measurements of its subregions at a more detailed level for a variety of species have not previously been made. Size measurements are reported here for the summed granular regions, DCN layers, AVCN, PVCN, and interstitial nucleus in 15 different rodent species, as well as a lagomorph, carnivore, and small primate. This further refinement of measurements is important because the granular regions and superficial layers of the DCN appear to have some different functions than the other cochlear nucleus regions. Except for DCN layers in the mountain beaver, all regions were clearly identifiable in all the animals studied. Relative regional size differences among most of the rodents, and even the 3 non-rodents, were not large and did not show a consistent relation to their wide range of lifestyles and hearing parameters. However, the mountain beaver, and to a lesser extent the pocket gopher, two rodents that live in tunnel systems, had relative sizes of summed granular regions and DCN molecular layer distinctly larger than those of the other mammals. Among all the mammals studied, there was a high correlation between the size per body weight of summed granular regions and that of the DCN molecular layer, consistent with other evidence for a close relationship between granule cells and superficial DCN neurons. PMID:27435005

  13. Functional architecture in the cell nucleus.

    PubMed Central

    Dundr, M; Misteli, T

    2001-01-01

    The major functions of the cell nucleus, including transcription, pre-mRNA splicing and ribosome assembly, have been studied extensively by biochemical, genetic and molecular methods. An overwhelming amount of information about their molecular mechanisms is available. In stark contrast, very little is known about how these processes are integrated into the structural framework of the cell nucleus and how they are spatially and temporally co-ordinated within the three-dimensional confines of the nucleus. It is also largely unknown how nuclear architecture affects gene expression. In order to understand how genomes are organized, and how they function, the basic principles that govern nuclear architecture and function must be uncovered. Recent work combining molecular, biochemical and cell biological methods is beginning to shed light on how the nucleus functions and how genes are expressed in vivo. It has become clear that the nucleus contains distinct compartments and that many nuclear components are highly dynamic. Here we describe the major structural compartments of the cell nucleus and discuss their established and proposed functions. We summarize recent observations regarding the dynamic properties of chromatin, mRNA and nuclear proteins, and we consider the implications these findings have for the organization of nuclear processes and gene expression. Finally, we speculate that self-organization might play a substantial role in establishing and maintaining nuclear organization. PMID:11368755

  14. Improved Cloud Condensation Nucleus Spectrometer

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2010-01-01

    An improved thermal-gradient cloud condensation nucleus spectrometer (CCNS) has been designed to provide several enhancements over prior thermal- gradient counters, including fast response and high-sensitivity detection covering a wide range of supersaturations. CCNSs are used in laboratory research on the relationships among aerosols, supersaturation of air, and the formation of clouds. The operational characteristics of prior counters are such that it takes long times to determine aerosol critical supersaturations. Hence, there is a need for a CCNS capable of rapid scanning through a wide range of supersaturations. The present improved CCNS satisfies this need. The improved thermal-gradient CCNS (see Figure 1) incorporates the following notable features: a) The main chamber is bounded on the top and bottom by parallel thick copper plates, which are joined by a thermally conductive vertical wall on one side and a thermally nonconductive wall on the opposite side. b) To establish a temperature gradient needed to establish a supersaturation gradient, water at two different regulated temperatures is pumped through tubes along the edges of the copper plates at the thermally-nonconductive-wall side. Figure 2 presents an example of temperature and supersaturation gradients for one combination of regulated temperatures at the thermally-nonconductive-wall edges of the copper plates. c) To enable measurement of the temperature gradient, ten thermocouples are cemented to the external surfaces of the copper plates (five on the top plate and five on the bottom plate), spaced at equal intervals along the width axis of the main chamber near the outlet end. d) Pieces of filter paper or cotton felt are cemented onto the interior surfaces of the copper plates and, prior to each experimental run, are saturated with water to establish a supersaturation field inside the main chamber. e) A flow of monodisperse aerosol and a dilution flow of humid air are introduced into the main

  15. Dynamics of hadron-nucleus interactions

    SciTech Connect

    Wallace, S.J.

    1981-07-01

    Recent progress in diffraction theory shows that proton-nucleus scattering at nonforward angles is dominated by the interference of waves from two or more bright spots. Analytic formulas based on asymptotic theories of diffraction yield valuable new insights into the scattering and these formulas can be readily extended to illuminate the role of dynamical ingredients, i.e., the nucleon-nucleon amplitudes. The governing parameters of the diffraction and some direct connections between the observed cross sections and the input dynamics are reviewed. New information regarding the nucleon-nucleon parameters based on recent phase shift analyses show some systematic differences from the effective NN amplitudes which produce fits to proton-nucleus diffraction data. Recent progress in understanding the role of ..delta..-isobars in proton-nucleus dynamics is reviewed. 126 references.

  16. The dynamic landscape of the cell nucleus.

    PubMed

    Austin, Christopher M; Bellini, Michel

    2010-01-01

    While the cell nucleus was described for the first time almost two centuries ago, our modern view of the nuclear architecture is primarily based on studies from the last two decades. This surprising late start coincides with the development of new, powerful strategies to probe for the spatial organization of nuclear activities in both fixed and live cells. As a result, three major principles have emerged: first, the nucleus is not just a bag filled with nucleic acids and proteins. Rather, many distinct functional domains, including the chromosomes, resides within the confines of the nuclear envelope. Second, all these nuclear domains are highly dynamic, with molecules exchanging rapidly between them and the surrounding nucleoplasm. Finally, the motion of molecules within the nucleoplasm appears to be mostly driven by random diffusion. Here, the emerging roles of several subnuclear domains are discussed in the context of the dynamic functions of the cell nucleus.

  17. The nucleus: a black box being opened.

    PubMed

    van Driel, R; Humbel, B; de Jong, L

    1991-12-01

    Until recently our knowledge about the structural and functional organization of the cell nucleus was very limited. Recent technical developments in the field of ultrastructural analysis, combined with ongoing research on the properties of the nuclear matrix, give new insight into how the nucleus is structured. Two types of observations shape our ideas about nuclear organization. First, most nuclear functions (replication, transcription, RNA processing, and RNA transport) are highly localized within the nucleus, rather than diffusely distributed. Moreover, they are associated with the nuclear matrix. Second, chromatin is organized in discrete loops, bordered by nuclear matrix attachment sequences (MARs). Each loop may contain one or several genes. The arrangement of chromatin in loops has profound consequences for the regulation of gene expression.

  18. Interpretive monitoring in the caudate nucleus

    PubMed Central

    Yanike, Marianna; Ferrera, Vincent P

    2014-01-01

    In a dynamic environment an organism has to constantly adjust ongoing behavior to adapt to a given context. This process requires continuous monitoring of ongoing behavior to provide its meaningful interpretation. The caudate nucleus is known to have a role in behavioral monitoring, but the nature of these signals during dynamic behavior is still unclear. We recorded neuronal activity in the caudate nucleus in monkeys during categorization behavior that changed rapidly across contexts. We found that neuronal activity maintained representation of the identity and context of a recently categorized stimulus, as well as interpreted the behavioral meaningfulness of the maintained trace. The accuracy of this cognitive monitoring signal was highest for behavior for which subjects were prone to make errors. Thus, the caudate nucleus provides interpretive monitoring of ongoing behavior, which is necessary for contextually specific decisions to adapt to rapidly changing conditions. DOI: http://dx.doi.org/10.7554/eLife.03727.001 PMID:25415238

  19. Hydrated nucleus pulposus herniation in seven dogs.

    PubMed

    Manunta, M L; Evangelisti, M A; Bergknut, N; Grinwis, G C M; Ballocco, I; Meij, B P

    2015-03-01

    The clinical signs, magnetic resonance imaging (MRI) findings, treatment and follow-up in seven dogs with hydrated nucleus pulposus extrusion (HNPE) are reported. All dogs had tetraparesis or tetraplegia. T2-weighted MRI revealed extradural hyperintense homogeneous material compressing the cervical spinal cord. After conservative treatment (five dogs) or surgical decompression (two dogs), all dogs returned to ambulatory function within 1 month. Follow-up MRI in conservatively treated dogs revealed complete disappearance of the extruded material. Histopathological examination of surgical specimens confirmed that the retrieved material was extruded nucleus pulposus with evidence of early degeneration. PMID:25599897

  20. Nucleus model for periodic Comet Tempel 2

    NASA Technical Reports Server (NTRS)

    Sekanina, Zdenek

    1991-01-01

    Observational data obtained primarily during 1988 are analyzed and synthesized to develop a comprehensive physical model for the nucleus of Periodic Comet Tempel 2, one of the best studied members of Jupiter's family of short-period comets. It is confirmed that a previous investigation provided reliable information on the comet's spin-axis orientation, which implies and obliquity of 54 degrees of the orbit plane to the equatorial plane and which appears to have varied little - if at all - with time. This conclusion is critical for fitting a triaxial ellipsoid to approximate the figure of the nucleus.

  1. UNCOVERING THE NUCLEUS CANDIDATE FOR NGC 253

    SciTech Connect

    Günthardt, G. I.; Camperi, J. A.; Agüero, M. P.; Díaz, R. J.; Gomez, P. L.; Schirmer, M.; Bosch, G. E-mail: camperi@oac.uncor.edu E-mail: rdiaz@gemini.edu E-mail: mschirmer@gemini.edu

    2015-11-15

    NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H{sub 2} rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this

  2. Compound Nucleus Contributions to the Optical Potential

    SciTech Connect

    Thompson, I J; Dietrich, F S; Escher, J E; Dupuis, M

    2008-01-28

    An ab-initio calculation of the optical potential for neutron-nucleus scattering has been performed by explicitly coupling the elastic channel to all the particle-hole (p-h) excitation states in the target. These p-h states may be regarded as doorway states through which the flux flows to more complicated configurations, and (in the end) to long-lived compound nucleus resonances. The random-phase approximation (RPA) provides the linear combinations of p-h states that include the residual interactions within the target, and we show preliminary results for elastic flux loss using both p-h and RPA descriptions of target excitations.

  3. Uncovering the Nucleus Candidate for NGC 253

    NASA Astrophysics Data System (ADS)

    Günthardt, G. I.; Agüero, M. P.; Camperi, J. A.; Díaz, R. J.; Gomez, P. L.; Bosch, G.; Schirmer, M.

    2015-11-01

    NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H2 rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this

  4. A Relativistic Multiple Scattering Theory for Nucleus-Nucleus Collisions with Delta Resonance Coupling

    NASA Astrophysics Data System (ADS)

    Werneth, Charles; Maung Maung, Khin; Norbury, John

    2012-10-01

    Non-relativistic multiple scattering theories (NRMST) are formulated by separating the unperturbed Hamiltonian from the interaction and writing the Lippmann-Schwinger equation as an infinite series in the multiple sums of pseudo two-body operators, known as the Watson tau-operators. The advantage of using the multiple scattering theory (MST) is that the pseudo two-body operators are often well approximated by free two-body nucleon-nucleon operators, which are obtained from parameterizations of experimental data. Relativistic theories are needed to properly describe the production of new particles, such as pions, from nucleus-nucleus collisions. Relativistic multiple scattering theories (RMST) have been developed for nucleon-nucleus scattering; however, no RMST for nucleus-nucleus scattering has yet been derived.footnotetextMaung K M, Norbury J W, and Coleman T 2007 J. Phys. G 34 1861. The purpose of this research is to derive an RMST for nucleus-nucleus scattering and to include delta degrees of freedom in the interaction, the minimum requirement for pion production.

  5. TWO-PHOTON PHYSICS IN NUCLEUS-NUCLEUS COLLISIONS AT RHIC.

    SciTech Connect

    NYSTRAND,J.

    1998-09-10

    Ultra-relativistic heavy-ions carry strong electromagnetic and nuclear fields. Interactions between these fields in peripheral nucleus-nucleus collisions can probe many interesting physics topics. This presentation will focus on coherent two-photon and photonuclear processes at RHIC. The rates for these interactions will be high. The coherent coupling of all the protons in the nucleus enhances the equivalent photon flux by a factor Z{sup 2} up to an energy of {approx} 3 GeV. The plans for studying coherent interactions with the STAR experiment will be discussed. Experimental techniques for separating signal from background will be presented.

  6. An organism arises from every nucleus.

    PubMed

    Keklikoglu, Nurullah

    2009-01-01

    The fact that, cloning using somatic cell nuclear transfer (SCNT) method has been performed, opened new horizons for cloning, and changed the way of our understanding and approach to cell and nucleus. The progress in cloning technology, brought the anticipation of the ability to clone an organism from each somatic cell nucleus. Therefore, the 'Cell Theory' is about to take the additional statement as "An organism arises from every nucleus". The development of gene targeting procedures which can be applied with SCNT, showed us that it may be possible to obtain different versions of the original genetic constitution of a cell. Because of this opportunity which is provided by SCNT, in reproductive cloning, it would be possible to clone enhanced organisms which can adapt to different environmental conditions and survive. Furthermore, regaining the genetic characteristics of ancestors or reverse herediter variations would be possible. On the other hand, in therapeutic cloning, more precise and easily obtainable alternatives for cell replacement therapy could be presented. However, while producing healthier or different organisms from a nucleus, it is hard to foresee the side effects influencing natural processes in long term is rather difficult.

  7. The Checkerboard Model of the Nucleus

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2015-04-01

    The Checker Board Model (CBM) of the nucleus and the associated extended standard model predicts that nature has 5 generations of quarks not 3 and that Nucleus is 2 dimensional. The CBM theory began with an insight into the structure of the He nucleus around the year 1989. Details of how this theory evolved which took many years, and is found on my web site (http://checkerboard.dnsalias.net) or in the following references One independent check of this model is that the wavelength of the ``up'' quark orbiting inside the proton at 84.8123% the speed of light (around the ``dn'' quark in the center of the proton) turns out to be exactly one de Broglie wavelength something determined after the mass and speed of the up quark were determined by other means. This theory explains the mass of the proton and neutron and their magnetic moments and this along with the beautiful symmetric 2D structure of the He nucleus led to the evolution of this theory. When this theory was first presented at Argonne in 1996, it was the first time that anyone had predicted the quarks orbited inside the proton at relativistic speeds and it was met with skepticism.

  8. The Nucleus and the Simple Microscope.

    ERIC Educational Resources Information Center

    Ford, Brian J.

    1982-01-01

    The 150th anniversary of the naming of the nucleus by Robert Brown in 1831 was commemorated by re-creating some of his most important observations using two of his microscopes. Comments on Brown's career and the microtechnique employed during his time are provided. (Author/JN)

  9. Correlation of transverse momentum and multiplicity in a superposition model of nucleus-nucleus collisions

    SciTech Connect

    Mrowczynski, Stanislaw

    2006-04-15

    In p-p collisions the average transverse momentum is known to be correlated with the multiplicity of produced particles. The correlation is shown to survive in a superposition model of nucleus-nucleus collisions. When properly parametrized, the correlation strength appears to be independent of the collision centrality--it is the same in p-p and central A-A collisions. However, the correlation is strongly suppressed by the centrality fluctuations.

  10. Average transverse momentum and energy density in high-energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1986-01-01

    Emulsion chambers were used to measure the transverse momenta of photons or pi(0) mesons produced in high-energy cosmic-ray nucleus-nucleus collisions. A group of events having large average transverse momenta has been found which apparently exceeds the expected limiting values. Analysis of the events at early interaction times, of the order of 1 fm/c, indicates that the observed transverse momentum increases with both rapidity density and energy density.

  11. Nucleus-nucleus total reaction cross sections, and the nuclear interaction radius

    SciTech Connect

    Abu-Ibrahim, Badawy

    2011-04-15

    We study the nucleus-nucleus total reaction cross sections for stable nuclei, in the energy region from 30A MeV to about 1A GeV, and find them to be in proportion to ({radical}({sigma}{sub pp}{sup tot}Z{sub 1}{sup 2/3}+{sigma}{sub pn}{sup tot}N{sub 1}{sup 2/3})+{radical}({sigma}{sub pp}{sup tot}Z{sub 2}{sup 2/3}+{sigma}{sub pn}{sup tot}N{sub 2}{sup 2/3})) {sup 2} in the mass range 8 to 100. Also, we find a parameter-free relation that enables us to predict a total reaction cross section for any nucleus-nucleus within 10% uncertainty at most, using the experimental value of the total reaction cross section of a given nucleus-nucleus. The power of the relation is demonstrated by several examples. The energy dependence of the nuclear interaction radius is deduced; it is found to be almost constant in the energy range from about 200A MeV to about 1A GeV; in this energy range and for nuclei with N=Z, R{sub I}(A)=(1.14{+-}0.02)A{sup 1/3} fm.

  12. The Neutrophil Nucleus and Its Role in Neutrophilic Function.

    PubMed

    Carvalho, Leonardo Olivieri; Aquino, Elaine Nascimento; Neves, Anne Caroline Dias; Fontes, Wagner

    2015-09-01

    The cell nucleus plays a key role in differentiation processes in eukaryotic cells. It is not the nucleus in particular, but the organization of the genes and their remodeling that provides the data for the adjustments to be made according to the medium. The neutrophil nucleus has a different morphology. It is a multi-lobed nucleus where some researchers argue no longer function. However, studies indicate that it is very probable the occurrence of chromatin remodeling during activation steps. It may be that the human neutrophil nucleus also contributes to the mobility of neutrophils through thin tissue spaces. Questions like these will be discussed in this small review. The topics include morphology of human neutrophil nucleus, maturation process and modifications of the neutrophil nucleus, neutrophil activation and chromatin modifications, causes and consequences of multi-lobulated segmented morphology, and importance of the nucleus in the formation of neutrophil extracellular traps (NETs).

  13. TOR-in(g) the nucleus.

    PubMed

    Tsang, Chi Kwan; Zheng, X F Steven

    2007-01-01

    Target of rapamycin (TOR) is a central component of the eukaryotic growth regulatory network. TOR controls the expression of diverse genes by all three RNA polymerases, including ribosome biogenesis, utilization and transport of nutrients, and stress-related genes. Until recently, TOR was thought to be a classical signaling kinase that regulates transcription factors in the cytoplasm. However, our recent study shows that in yeast, TOR dynamically shuttles between the cytoplasm and nucleus, and binds to 35S ribosomal DNA (rDNA) promoter. Importantly, nuclear localization and promoter-binding is crucial for TOR to control RNA polymerase (Pol) I-dependent 35S rDNA transcription. In contrast, either cytoplasmic or nuclear TOR is sufficient to regulate Pol II-dependent transcription. These observations suggest that TOR in the nucleus plays an important role in gene regulation, and that TOR takes a multifaceted approach to control expression of different genes.

  14. How the nucleus copes with proteotoxic stress.

    PubMed

    Shibata, Yoko; Morimoto, Richard I

    2014-05-19

    The proper folding of proteins is continuously challenged by intrinsic and extrinsic stresses, and the accumulation of toxic misfolded proteins is associated with many human diseases. Eukaryotic cells have evolved a complex network of protein quality control pathways to protect the proteome, and these pathways are specialized for each subcellular compartment. While many details have been elucidated for how the cytosol and endoplasmic reticulum counteract proteotoxic stress, relatively little is known about the pathways protecting the nucleus from protein misfolding. Proper maintenance of nuclear proteostasis has important implications in preserving genomic integrity, as well as for aging and disease. Here, we offer a conceptual framework for how proteostasis is maintained in this organelle. We define the particular requirements that must be considered for the nucleus to manage proteotoxic stress, summarize the known and implicated pathways of nuclear protein quality control, and identify the unresolved questions in the field.

  15. Cell Nucleus-Targeting Zwitterionic Carbon Dots

    PubMed Central

    Jung, Yun Kyung; Shin, Eeseul; Kim, Byeong-Su

    2015-01-01

    An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation. PMID:26689549

  16. Cell Nucleus-Targeting Zwitterionic Carbon Dots.

    PubMed

    Jung, Yun Kyung; Shin, Eeseul; Kim, Byeong-Su

    2015-12-22

    An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation.

  17. Coherency in neutrino-nucleus elastic scattering

    NASA Astrophysics Data System (ADS)

    Kerman, S.; Sharma, V.; Deniz, M.; Wong, H. T.; Chen, J.-W.; Li, H. B.; Lin, S. T.; Liu, C.-P.; Yue, Q.; Texono Collaboration

    2016-06-01

    Neutrino-nucleus elastic scattering provides a unique laboratory to study the quantum mechanical coherency effects in electroweak interactions, towards which several experimental programs are being actively pursued. We report results of our quantitative studies on the transitions towards decoherency. A parameter (α ) is identified to describe the degree of coherency, and its variations with incoming neutrino energy, detector threshold, and target nucleus are studied. The ranges of α that can be probed with realistic neutrino experiments are derived, indicating complementarity between projects with different sources and targets. Uncertainties in nuclear physics and in α would constrain sensitivities in probing physics beyond the standard model. The maximum neutrino energies corresponding to α >0.95 are derived.

  18. Core-nucleus distortation in hypernuclei

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We are completing a study of the effects of the spherical distortion of the {open_quotes}core{close_quotes} nucleus by the {Lambda} in a hypernucleus. The response of the core was determined by an appropriately chosen energy-density functional which depends, in particular, on the nuclear compressibility. The forcing action of the A is determined by the nuclear density dependence of the {Lambda} binding in nuclear matter which is obtained from our work on the {Lambda} single-particle energies. Because of the strongly repulsive {Lambda}NN forces, this {Lambda} binding {open_quotes}saturates{close_quotes} at a density close to the central density of nuclei, and results in a reduced core-nucleus distortion much less than would otherwise be obtained. The effects of the core distortion then turn out to be very small even for quite light hypernuclei. This result justifies the assumption that spherical core nuclei are effectively undistorted in a hypernucleus.

  19. Development of a Mobile Ice Nucleus Counter

    SciTech Connect

    Kok, Gregory; Kulkarni, Gourihar

    2014-07-10

    An ice nucleus counter has been constructed. The instrument uses built-in refrigeration systems for wall cooling. A cascade refrigeration system will allow the cold wall to operate as low as -70 deg C, and a single stage system can operate the warm wall at -45 deg C. A unique optical particle counter has been constructed using polarization detection of the scattered light. This allows differentiation of the particles exiting the chamber to determine if they are ice or liquid.

  20. Physical Properties of Cometary Nucleus Candidates

    NASA Technical Reports Server (NTRS)

    Jewitt, David; Hillman, John (Technical Monitor)

    2003-01-01

    In this proposal we aim to study the physical properties of the Centaurs and the dead comets, these being the precursors to, and the remnants from, the active cometary nuclei. The nuclei themselves are very difficult to study, because of the contaminating effects of near-nucleus coma. Systematic investigation of the nuclei both before they enter the zone of strong sublimation and after they have depleted their near-surface volatiles should neatly bracket the properties of these objects, revealing evolutionary effects.

  1. Parity violation in the compound nucleus

    SciTech Connect

    Mitchell, G. E.; Crawford, B. E.; Grossmann, C. A.; Lowie, L. Y.; Bowman, J. D.; Knudson, J.; Penttilae, S.; Seestrom, S. J.; Smith, D. A.; Yen, Yi-Fen; Yuan, V. W.; Delheij, P. P. J.; Haseyama, T.; Masaike, A.; Matsuda, Y.; Postma, H.; Roberson, N. R.; Sharapov, E. I.; Stephenson, S. L.

    1999-06-10

    Measurements have been performed on the helicity dependence of the neutron resonance cross section for many nuclei by our TRIPLE Collaboration. A large number of parity violations are observed. Generic enhancements amplify the signal for symmetry breaking and the stochastic properties of the compound nucleus permit the strength of the symmetry-breaking interaction to be determined without knowledge of the wave functions of individual states. A total of 15 nuclei have been analyzed with this statistical approach. The results are summarized.

  2. Revisiting the supratrigeminal nucleus in the rat.

    PubMed

    Fujio, T; Sato, F; Tachibana, Y; Kato, T; Tomita, A; Higashiyama, K; Ono, T; Maeda, Y; Yoshida, A

    2016-06-01

    The supratrigeminal nucleus (Vsup), originally proposed as a premotoneuron pool in the trigeminal reflex arc, is a key structure of jaw movement control. Surprisingly, however, the location of the rat Vsup has not precisely been defined. In light of our previous cat studies, we made two hypotheses regarding the rat Vsup: (1) the Vsup is cytoarchitectonically distinguishable from its surrounding structures; (2) the Vsup receives central axon terminals of the trigeminal mesencephalic nucleus (Vmes) neurons which are primary afferents innervating muscle spindles of jaw-closing muscles and periodontal ligaments around the teeth. To test the first hypothesis, we examined the cytoarchitecture of the rat Vsup. The Vsup was identified as an area medially adjacent to the dorsomedial part of trigeminal principal sensory nucleus (Vp), and extended from the level just rostral to the caudal two-thirds of the trigeminal motor nucleus (Vmo) to the level approximately 150 μm caudal to the Vmo. Our rat Vsup was much smaller and its location was considerably different in comparison to the Vsup reported previously. To evaluate the second hypothesis, we tested the distribution patterns of Vmes primary afferent terminals in the cytoarchitectonically identified Vsup. After transganglionic tracer applications to the masseter, deep temporal, and medial pterygoid nerves, a large number of axon terminals were observed in all parts of Vsup (especially in its medial part). After applications to the inferior alveolar, infraorbital, and lingual nerves, a small number of axon terminals were labeled in the caudolateral Vsup. The Vsup could also be identified electrophysiologically. After electrical stimulation of the masseter nerve, evoked potentials with slow negative component were isolated only in the Vsup. The present findings suggest that the rat Vsup can be cytoarchitectonically and electrophysiologically identified, receives somatotopic termination of the trigeminal primary afferents, and

  3. Functional morphology of the suprachiasmatic nucleus.

    PubMed

    Ibata, Y; Okamura, H; Tanaka, M; Tamada, Y; Hayashi, S; Iijima, N; Matsuda, T; Munekawa, K; Takamatsu, T; Hisa, Y; Shigeyoshi, Y; Amaya, F

    1999-07-01

    In mammals, the biological clock (circadian oscillator) is situated in the suprachiasmatic nucleus (SCN), a small bilaterally paired structure just above the optic chiasm. Circadian rhythms of sleep-wakefulness and hormone release disappear when the SCN is destroyed, and transplantation of fetal or neonatal SCN into an arrhythmic host restores rhythmicity. There are several kinds of peptide-synthesizing neurons in the SCN, with vasoactive intestinal peptide, arginine vasopressin, and somatostatine neurons being most prominent. Those peptides and their mRNA show diurnal rhythmicity and may or may not be affected by light stimuli. Major neuronal inputs from retinal ganglion cells as well as other inputs such as those from the lateral geniculate nucleus and raphe nucleus are very important for entrainment and shift of circadian rhythms. In this review, we describe morphological and functional interactions between neurons and glial elements and their development. We also consider the expression of immediate-early genes in the SCN after light stimulation during subjective night and their role in the mechanism of signal transduction. The reciprocal interaction between the SCN and melatonin, which is synthesized in the pineal body under the influence of polysynaptic inputs from the SCN, is also considered. Finally, morphological and functional characteristics of clock genes, particularly mPers, which are considered to promote circadian rhythm, are reviewed. PMID:10433864

  4. [Venous vascularization of the lentiform nucleus].

    PubMed

    Wolfram-Gabel, R; Maillot, C

    The venous vascularization of the nucleus lentiformis in man is studied in 30 brains by injecting the vascular system with gelatinous Indian ink. The venous vascularization of the nucleus lentiformis is drained towards the deep venous system of the brain by two ways, one ascending, the other descending. The first one is formed by superior lenticular veins which drain into the thalamo-striate vein, principal tributary of the internal cerebral vein. The second one is formed by inferior lenticular veins which depend from the deep middle cerebral vein, another tributary of the internal cerebral vein. The veins of the nucleus lentiformis, especially the veins of the putamen, present many similarities with these one of the cerebral cortex. They form the center of venous units surrounded by an arterial ring formed by the branches of ramification of the central arteries. The principal vein of the unit is surrounded by a capillary-free space. This similarities may be explained by the common origin of the cerebral cortex and of the putamen, both belong to the neocortical system.

  5. The nucleus basalis in Huntington's disease.

    PubMed

    Clark, A W; Parhad, I M; Folstein, S E; Whitehouse, P J; Hedreen, J C; Price, D L; Chase, G A

    1983-10-01

    The nucleus basalis of Meynert (nbM) provides most of the cholinergic input to the cerebral cortex. The loss of cortical choline acetyltransferase (CAT) activity in Alzheimer's disease (AD) and senile dementia of the Alzheimer's type (SDAT) appears to be related to a severe depopulation of the nbM in this dementia. In Huntington's disease (HD), by contrast, there is no loss of cortical CAT activity. The present quantitative study indicates that (1) there is no significant loss of neurons from the nbM in HD, and (2) that the previously described cytologic changes in the neurons of this nucleus in HD patients do not differ significantly from controls. These findings are consistent with the working hypothesis that the types of dementia associated with reductions of neocortical CAT activity are characterized by dysfunction or death of neurons in the nbM, but dementing disorders with normal neocortical CAT activity manifest no major abnormalities in this cholinergic nucleus of the basal forebrain. PMID:6225032

  6. Comet nucleus and asteroid sample return missions

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.

  7. Comet nucleus and asteroid sample return missions

    NASA Astrophysics Data System (ADS)

    1992-06-01

    Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.

  8. Low P sub T hadron-nucleus interactions

    NASA Technical Reports Server (NTRS)

    Holynski, R.; Wozniak, K.

    1985-01-01

    The possibility of describing hadron-nucleus (hA) interactions is discussed in terms of a number of independent collisions of the projectile inside the target nucleus. This multiple rescattering may occur on a particle or quark parton level. To investigate the characteristics of hA interactions as a function of antineutrinos advantage is taken of the correlation between the average number antineutrinos of collisions of the projectile inside the nucleus and the number Ng of fast protons ejected from the struck nucleus. The relation antineutrinos vs Ng obtained in antineutrinos was used. For a given target nucleus this allows the selection of interactions occurring at different impact parameters.

  9. a Unified Approach to Hadron-Hadron Hadron-Nucleus and Nucleus-Nucleus Collisions at High Energy

    NASA Astrophysics Data System (ADS)

    Wang, Xin-Nian

    The problem of multiparticle production in high -energy hadron-hadron, hadron-nucleus and nucleus-nucleus collisions are studied systematically in the framework of the Geometrical Branching Model (GBM). The model is based on the geometrical properties of nucleons and the stochastic nature of the interaction among the soft partons. The eikonal formalism is used to relate the elastic and inelastic cross sections and AGK cutting rule is used in connection with the multiparticle production process. The stochastic process of Furry branching is employed to describe the proliferation and hadronization of partons which lead to the produced particles. The approach describes hh, hA and AA collisions in a unified formalism for c.m. energies less than 100 GeV. The result of multiplicity distribution of produced particles exhibits Koba-Nielsen-Olesen (KNO) scaling. The universality of KNO scaling breaks down due to the different geometrical sizes of the hadron and nuclei. For hA and AA collisions, the formalism of GBM allows the hadron to be broken (to h^') by the first collision; indeed, it is the attention given to h^'h and h ^'h^' collisions that distinguishes this work from other earlier investigations on the subject. All of the calculated results are in good agreement with experiments. A general Monte Carlo simulation of GBM for multiparticle production in hh, hA and AA collisions is also given. The particle productivity in particular is studied in detail and is contrasted from the case where quark-gluon plasma (QGP) is produced in the AA collisions. This work forms a definitive description of hadronic and nuclear collisions that can serve as a basis from which exotic features such as the formation of QGP can be recognized as signatures deviating from the normal background.

  10. The orientation of nucleus, nucleus-associated body and protruding nucleolus in aggregating Dictyostelium discoideum.

    PubMed

    Sameshima, M

    1985-02-01

    Dictyostelium discoideum growing or developing on cellulose dialysis membranes were fixed with acrolein vapour for electron microscopy. In interphase amoebae, nucleoli began to protrude from the nuclei. The percentage of cells with protruding nucleoli increased during aggregation by a value approximately twice as high in aggregation streams as in centers. Cells in pseudoplasmodia showed only a low percentage and protrusions disappeared at early culmination stage. The protrusions did not reappear when cells from dissociated pseudoplasmodia migrated toward cAMP. Thus the formation of the protrusions did not depend solely on chemotaxis; rather, it was specific to the aggregation stage. In aggregation streams, the nucleus was anterior in the cell, with the protrusion at its anterior periphery. In contrast, the nucleus associated body (NAB) was evident at the cell's mid-point. This orientation of nucleus and NAB in the aggregating slime mould amoeba is contrary to that seen in human neutrophils or cultured mouse 3T3 cells. PMID:2981691

  11. Nuclear radii calculations in various theoretical approaches for nucleus-nucleus interactions

    SciTech Connect

    Merino, C.; Novikov, I. S.; Shabelski, Yu.

    2009-12-15

    The information about sizes and nuclear density distributions in unstable (radioactive) nuclei is usually extracted from the data on interaction of radioactive nuclear beams with a nuclear target. We show that in the case of nucleus-nucleus collisions the values of the parameters depend somewhat strongly on the considered theoretical approach and on the assumption about the parametrization of the nuclear density distribution. The obtained values of root-mean-square radii (R{sub rms}) for stable nuclei with atomic weights A=12-40 vary by approximately 0.1 fm when calculated in the optical approximation, in the rigid target approximation, and using the exact expression of the Glauber theory. We present several examples of R{sub rms} radii calculations using these three theoretical approaches and compare these results with the data obtained from electron-nucleus scattering.

  12. Observation of direct hadronic pairs in nucleus-nucleus collisions in JACEE emulsion chambers

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.

    1985-01-01

    In a number of high energy ( or = 1 TeV/amu) nucleus-nucleus collisions observed in Japanese-American Cooperative Emulsion Experiment (JACEE) emulsion chambers, nonrandom spatial association of produced charged particles, mostly hadronic pairs, are observed. Similar narrow pairs are observed in about 100 events at much low energy (20 to 60 GeV/amu). Analysis shows that 30 to 50% of Pair abundances are understood by the Hambury-Brown-Twiss effect, and the remainder seems to require other explanations.

  13. Pion and Kaon Lab Frame Differential Cross Sections for Intermediate Energy Nucleus-Nucleus Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Blattnig, Steve R.

    2008-01-01

    Space radiation transport codes require accurate models for hadron production in intermediate energy nucleus-nucleus collisions. Codes require cross sections to be written in terms of lab frame variables and it is important to be able to verify models against experimental data in the lab frame. Several models are compared to lab frame data. It is found that models based on algebraic parameterizations are unable to describe intermediate energy differential cross section data. However, simple thermal model parameterizations, when appropriately transformed from the center of momentum to the lab frame, are able to account for the data.

  14. Electromagnetic processes in nucleus-nucleus collisions relating to space radiation research

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Most of the papers within this report deal with electromagnetic processes in nucleus-nucleus collisions which are of concern in the space radiation program. In particular, the removal of one and two nucleons via both electromagnetic and strong interaction processes has been extensively investigated. The theory of relativistic Coulomb fission has also been developed. Several papers on quark models also appear. Finally, note that the theoretical methods developed in this work have been directly applied to the task of radiation protection of astronauts. This has been done by parameterizing the theoretical formalism in such a fashion that it can be used in cosmic ray transport codes.

  15. Neuronal loss in human medial vestibular nucleus.

    PubMed

    Alvarez, J C; Díaz, C; Suárez, C; Fernández, J A; González del Rey, C; Navarro, A; Tolivia, J

    1998-08-01

    The data concerning the effects of age on the brainstem are inconsistent, and few works are devoted to the human vestibular nuclear complex. The medial vestibular nucleus (MVN) is the largest nucleus of the vestibular nuclear complex, and it seems to be related mainly to vestibular compensation and vestibulo-ocular reflexes. Eight human brainstems have been used in this work. The specimens were embedded in paraffin, sectioned, and stained by the formaldehyde-thionin technique. Neuron profiles were drawn with a camera lucida at x330. Abercrombie's method was used to estimate the total number of neurons. We used the test of Kolmogorov-Smirnov with the correction of Lilliefors to evaluate the fit of our data to a normal distribution, and a regression analysis was performed to determine if the variation of our data with age was statistically significant. The present study clearly shows that neuronal loss occurs with aging. The total number of neurons decreases with age, from 122,241 +/- 651 cells in a 35-year-old individual to 75,915 +/- 453 cells in an 89-year-old individual. Neuron loss was significant in the caudal and intermediate thirds of the nucleus, whereas the changes in the rostral third were not significant. The nuclear diameter of surviving neurons decreased significantly with age. There is a neuron loss in the MVN that seems to be age-related. It could help explain why elderly people find it hard to compensate for unilateral vestibular deficits. The preservation of neurons in the rostral third could be related to the fact that this area primarily innervates the oculolmotor nuclei; these latter neurons do not decrease in number in other species studied.

  16. The Checkerboard Model of the Nucleus

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2014-03-01

    The Lach Checker Board Model (CBM) of the nucleus and the associated ESM predicts that nature has 5 generations of quarks not 3. The heaviest generation in the Extended Standard Model (ESM) has a t' quark of mass 65 GeV and a b' quark of 42.4 GeV. The lepton in this generation has a mass of 27 GeV. Part of this theory evolved because it appears that the quarks and lepton of each generation have masses related by the geometric mean. The Geometric mean of 65 and 27 is 42. Charge is conserved (+2/3 and -1 is -1/3). Details of how this theory evolved is found on my web site (http://checkerboard.dnsalias.net) or in the following references [T.M. Lach, Checkerboard Structure of the Nucleus, Infinite Energy, Vol. 5, issue 30, (2000); T.M. Lach, Masses of the Sub-Nuclear Particles, nucl-th/0008026, @http://xxx.lanl.gov/] One independent check of this CB model is that the wavelength of the ``up'' quark orbiting inside the proton at 84.8123% the speed of light around the ``dn'' quark in the center turns out to be exactly one DeBroglie wavelength. This explains the mass of the proton and neutron and their magnetic moments. This along with the beautiful symmetric 2D structure of the He nucleus led to the evolution of this theory. One would expect a t'-anti t' meson of mass of about 130 GeV.

  17. [The perichromatin compartment of the cell nucleus].

    PubMed

    Bogoliubov, D S

    2014-01-01

    In this review, the data on the structure and composition of the perichromatin compartment, a special border area between the condensed chromatin and the interchromatin space of the cell nucleus, are discussed in the light of the concept of nuclear functions in complex nuclear architectonics. Morphological features, molecular composition and functions of main extrachromosomal structures of the perichromatin compartment, perichromatin fibrils (PFs) and perichromatin granules (PGs) including nuclear stress-bodies (nSBs) that are derivates of the PGs under heat shock, are presented. A special attention was paid to the features of the molecular compositions of PFs and PGs in different cell types and at different physiological conditions. PMID:25696976

  18. Neutrino-nucleus scattering off 136Xe

    NASA Astrophysics Data System (ADS)

    Ydrefors, E.; Suhonen, J.; Zhao, Y. M.

    2015-01-01

    Background: Theoretical estimates of the cross sections for the neutrino-nucleus scattering off relevant nuclei for supernova neutrinos are essential for many applications in neutrino physics and astrophysics. The double-β -decaying nucleus 136Xe nucleus is used by the EXO Collaboration in the search for neutrinoless double-β decay. A ton-scale experiment based on 136Xe could also be used for studies of supernova neutrinos and/or solar neutrinos. Purpose: The purpose of the present work is, thus, to perform a study of the charged-current and neutral-current nuclear responses to supernova neutrinos for 136Xe . Method: The cross sections are computed by using the well-established framework for studies of semileptonic processes in nuclei introduced by O'Connell, Donnelly, and Walecka [Phys. Rev. C 6, 719 (1972), 10.1103/PhysRevC.6.719]. The nuclear wave functions of the initial and the final nuclear states for the neutral-current neutrino-nucleus scattering in 136Xe are computed by using the quasiparticle random-phase approximation (QRPA). Similarly, the pnQRPA is adopted to construct the initial and final nuclear states which are relevant for the charged-current reactions. The nuclear responses to supernova neutrinos are subsequently computed by folding the cross sections with appropriate energy spectra for the incoming neutrinos. Results: We present results for the cross sections of the charged-current and neutral-current neutrino and antineutrino scatterings off 136Xe . Nuclear responses to supernova neutrinos are also given. For the considered scenario for the neutrino mixing we have found that neutrino interactions with matter and so-called collective neutrino oscillations enhance significantly the neutrino and antineutrino flux-averaged cross sections. Conclusions: We have found that for the charged-current and neutral-current neutrino scatterings off 136Xe transitions mediated by the 1+ multipole are the most important ones. However, for the charged

  19. [The perichromatin compartment of the cell nucleus].

    PubMed

    Bogoliubov, D S

    2014-01-01

    In this review, the data on the structure and composition of the perichromatin compartment, a special border area between the condensed chromatin and the interchromatin space of the cell nucleus, are discussed in the light of the concept of nuclear functions in complex nuclear architectonics. Morphological features, molecular composition and functions of main extrachromosomal structures of the perichromatin compartment, perichromatin fibrils (PFs) and perichromatin granules (PGs) including nuclear stress-bodies (nSBs) that are derivates of the PGs under heat shock, are presented. A special attention was paid to the features of the molecular compositions of PFs and PGs in different cell types and at different physiological conditions.

  20. Nuclear mechanotransduction: forcing the nucleus to respond.

    PubMed

    Guilluy, Christophe; Burridge, Keith

    2015-01-01

    Cell phenotype and fate are driven by the mechanical properties of their surrounding environment. Changes in matrix rigidity or application of force have been shown to impact profoundly cell behavior and phenotype, demonstrating that the molecular mechanisms which "sense" and transduce these signals into biochemical pathways are central in cell biology. In this commentary, we discuss recent evidence showing that mechanotransduction mechanisms occur in the nucleus, allowing dynamic regulation of the nucleoskeleton in response to mechanical stress. We will review this nucleoskeletal response and its impact on both nuclear structure and function.

  1. Parity violation in the compound nucleus

    SciTech Connect

    Mitchell, G.E.; Crawford, B.E.; Grossmann, C.A.; Lowie, L.Y.; Bowman, J.D.; Knudson, J.; Penttilae, S.; Seestrom, S.J.; Smith, D.A.; Yen, Y.; Yuan, V.W.; Delheij, P.P.; Haseyama, T.; Masaike, A.; Matsuda, Y.; Postma, H.; Roberson, N.R.; Sharapov, E.I.; Stephenson, S.L.

    1999-06-01

    Measurements have been performed on the helicity dependence of the neutron resonance cross section for many nuclei by our TRIPLE Collaboration. A large number of parity violations are observed. Generic enhancements amplify the signal for symmetry breaking and the stochastic properties of the compound nucleus permit the strength of the symmetry-breaking interaction to be determined without knowledge of the wave functions of individual states. A total of 15 nuclei have been analyzed with this statistical approach. The results are summarized. {copyright} {ital 1999 American Institute of Physics.}

  2. Dust activity of Comet Halley's nucleus

    NASA Technical Reports Server (NTRS)

    Keller, H. U.; Delamere, W. A.; Huebner, W. F.; Reitsema, H.; Schmidt, H. U.; Schmidt, W. K. H.; Whipple, Fred L.; Wilhelm, K.

    1986-01-01

    Images obtained by the Halley multicolor camera using the clear filter with a pass band from 300 to 1000 nm were used to study dust activity in the comet nucleus. Comparisons with ground based observations confirm that dust production towards the Sun increases in activity relative to the southern background source while the Giotto spacecraft was approaching. This is in agreement with the assumption that the sunward activity becomes stronger when the source rotates towards the Sun. Estimated dust column density is 90 billion/sqm, with optical thickness less than or = 0.3. Surface reflectivity is less than 1%, indicating a very rough surface with large fractions of shadowed areas.

  3. Paraventricular hypothalamic nucleus: axonal projections to the brainstem

    PubMed Central

    Geerling, Joel C.; Shin, Jung-Won; Chimenti, Peter C.; Loewy, Arthur D.

    2010-01-01

    The paraventricular hypothalamic nucleus (PVH) contains many neurons that innervate the brainstem, but information regarding their target sites remains incomplete. Here, we labeled neurons in the rat PVH with an anterograde axonal tracer, Phaseolus vulgaris leucoagglutinin (PHAL) and studied their descending projections in reference to specific neuronal subpopulations throughout the brainstem. While many of their target sites were identified previously, numerous new observations were made. Major findings include: (1) In the midbrain, the PVH projects lightly to the ventral tegmental area, Edinger-Westphal nucleus, ventrolateral periaqueductal gray matter, reticular formation, pedunculopontine tegmental nucleus, and dorsal raphe nucleus. (2) In the dorsal pons, the PVH projects heavily to the pre-locus coeruleus, yet very little to the catecholamine neurons in the locus coeruleus, and selectively targets the viscerosensory subregions of the parabrachial nucleus; (3) In the ventral medulla, the superior salivatory nucleus, retrotrapezoid nucleus, compact and external formations of the nucleus ambiguus, A1 and caudal C1 catecholamine neurons, and caudal pressor area receive dense axonal projections, generally exceeding the PVH projection to the rostral C1 region; (4) The medial nucleus of the solitary tract (including A2 noradrenergic and aldosterone-sensitive neurons) receives the most extensive projections of the PVH, substantially more than the dorsal vagal nucleus or area postrema. Our findings suggest that the PVH may modulate a range of homeostatic functions, including cerebral and ocular blood flow, corneal and nasal hydration, ingestive behavior, sodium intake, and glucose metabolism, as well as cardiovascular, gastrointestinal, and respiratory activities. PMID:20187136

  4. A thalamic input to the nucleus accumbens mediates opiate dependence.

    PubMed

    Zhu, Yingjie; Wienecke, Carl F R; Nachtrab, Gregory; Chen, Xiaoke

    2016-02-11

    Chronic opiate use induces opiate dependence, which is characterized by extremely unpleasant physical and emotional feelings after drug use is terminated. Both the rewarding effects of a drug and the desire to avoid withdrawal symptoms motivate continued drug use, and the nucleus accumbens is important for orchestrating both processes. While multiple inputs to the nucleus accumbens regulate reward, little is known about the nucleus accumbens circuitry underlying withdrawal. Here we identify the paraventricular nucleus of the thalamus as a prominent input to the nucleus accumbens mediating the expression of opiate-withdrawal-induced physical signs and aversive memory. Activity in the paraventricular nucleus of the thalamus to nucleus accumbens pathway is necessary and sufficient to mediate behavioural aversion. Selectively silencing this pathway abolishes aversive symptoms in two different mouse models of opiate withdrawal. Chronic morphine exposure selectively potentiates excitatory transmission between the paraventricular nucleus of the thalamus and D2-receptor-expressing medium spiny neurons via synaptic insertion of GluA2-lacking AMPA receptors. Notably, in vivo optogenetic depotentiation restores normal transmission at these synapses and robustly suppresses morphine withdrawal symptoms. This links morphine-evoked pathway- and cell-type-specific plasticity in the paraventricular nucleus of the thalamus to nucleus accumbens circuit to opiate dependence, and suggests that reprogramming this circuit holds promise for treating opiate addiction.

  5. Nuclear mean field and double-folding model of the nucleus-nucleus optical potential

    NASA Astrophysics Data System (ADS)

    Khoa, Dao T.; Phuc, Nguyen Hoang; Loan, Doan Thi; Loc, Bui Minh

    2016-09-01

    Realistic density dependent CDM3Yn versions of the M3Y interaction have been used in an extended Hartree-Fock (HF) calculation of nuclear matter (NM), with the nucleon single-particle potential determined from the total NM energy based on the Hugenholtz-van Hove theorem that gives rise naturally to a rearrangement term (RT). Using the RT of the single-nucleon potential obtained exactly at different NM densities, the density and energy dependence of the CDM3Yn interactions was modified to account properly for both the RT and observed energy dependence of the nucleon optical potential. Based on a local density approximation, the double-folding model of the nucleus-nucleus optical potential has been extended to take into account consistently the rearrangement effect and energy dependence of the nuclear mean-field potential, using the modified CDM3Yn interactions. The extended double-folding model was applied to study the elastic 12C+12C and 16O+12C scattering at the refractive energies, where the Airy structure of the nuclear rainbow has been well established. The RT was found to affect significantly the real nucleus-nucleus optical potential at small internuclear distances, giving a potential strength close to that implied by the realistic optical model description of the Airy oscillation.

  6. How dynein and microtubules rotate the nucleus.

    PubMed

    Wu, Jun; Lee, Kristen C; Dickinson, Richard B; Lele, Tanmay P

    2011-10-01

    In living cells, a fluctuating torque is exerted on the nuclear surface but the origin of the torque is unclear. In this study, we found that the nuclear rotation angle is directionally persistent on a time scale of tens of minutes, but rotationally diffusive on longer time scales. Rotation required the activity of the microtubule motor dynein. We formulated a model based on microtubules undergoing dynamic instability, with tensional forces between a stationary centrosome and the nuclear surface mediated by dynein. Model simulations suggest that the persistence in rotation angle is due to the transient asymmetric configuration of microtubules exerting a net torque in one direction until the configuration is again randomized by dynamic instability. The model predicts that the rotational magnitude must depend on the distance between the nucleus and the centrosome. To test this prediction, rotation was quantified in patterned cells in which the cell's centrosome was close to the projected nuclear centroid. Consistent with the prediction, the angular displacement was found to decrease in these cells relative to unpatterned cells. This work provides the first mechanistic explanation for how nuclear dynein interactions with discrete microtubules emanating from a stationary centrosome cause rotational torque on the nucleus.

  7. On M31's Double Nucleus

    NASA Technical Reports Server (NTRS)

    Miller, R. H.; Smith, B. F.; Cuzzi, Jeffrey (Technical Monitor)

    1995-01-01

    The recent HST discovery of a double nucleus in M31 brings into prominence the question how long, a second core can survive within the nuclear regions of a galaxy. Physical conditions in the nuclear regions of a typical galaxy help a second core survive, so it can orbit for a long time. possibly for thousands of orbits. Given the nearly uniform mass density in a core, tidal forces within a core radius are compressive in all directions and help the core survive the buffeting it takes as it orbits near the center of the galaxy. We use numerical experiments to illustrate these physical principles. Our method allows the full power of the experiments to be concentrated on the nuclear regions. Spatial resolution of about 0.2 pc comfortably resolves detail within the 1.4 parsec core radius of the second, but brighter core (P1) in M31. We use these physical principles to discuss M31's double nucleus, but they apply to other galaxies as well. and in other astronomical situations such as dumbbell galaxies. galaxies orbiting near the center of a galaxy cluster, and subclustering in galaxy clusters. The experiments also illustrate that galaxy encounters and merging are quite sensitive to external tidal forces, such as those produced by the gravitational potential in a group or cluster of galaxies.

  8. Caudal topographic nucleus isthmi and the rostral nontopographic nucleus isthmi in the turtle, Pseudemys scripta.

    PubMed

    Sereno, M I; Ulinski, P S

    1987-07-15

    Isthmotectal projections in turtles were examined by making serial section reconstructions of axonal and dendritic arborizations that were anterogradely or retrogradely filled with HRP. Two prominent tectal-recipient isthmic nuclei--the caudal magnocellular nucleus isthmi (Imc) and the rostral magnocellular nucleus isthmi (Imr)--exhibited strikingly different patterns of organization. Imc cells have flattened, bipolar dendritic fields that cover a few percent of the area of the cell plate constituting the nucleus and they project topographically to the ipsilateral tectum without local axon branches. The topography was examined explicitly at the single-cell level by using cases with two injections at widely separated tectal loci. Each Imc axon terminates as a compact swarm of several thousand boutons placed mainly in the upper central gray and superficial gray layers. One Imc terminal spans less that 1% of the tectal surface. Imr cells, by contrast, have large, sparsely branched dendritic fields overlapped by local axon collaterals while distally, their axons nontopographically innervate not only the deeper layers of the ipsilateral tectum but also ipsilateral Imc. Imr receives a nontopographic tectal input that contrasts with the topographic tectal input to Imc. Previous work on nucleus isthmi emphasized the role of the contralateral isthmotectal projection (which originates from a third isthmic nucleus in turtles) in mediating binocular interactions in the tectum. The present results on the two different but overlapping ipsilateral tecto-isthmo-tectal circuits set up by Imc and Imr are discussed in the light of physiological evidence for selective attention effects and local-global interactions in the tectum.

  9. Odyssey Comet Nucleus Orbiter: The Next Step in Cometary Exploration

    NASA Astrophysics Data System (ADS)

    Weissman, P. R.; Nilsen, E. N.; Smythe, W. D.; Marriott, J.; Reinert, R.

    2001-01-01

    Cometary nuclei are the most primitive bodies in the solar system, containing a cosmo-chemical record of the primordial solar nebula. Flyby missions to comets, such as those that encountered Comet Halley in 1986, provide a glimpse at this record. However, to study a cometary nucleus in detail requires a rendezvous mission, i.e., a nucleus orbiter. Only an orbiter provides the ability to map the entire nucleus surface at high resolution, to study the complex chemistry in the cometary coma and its variation with time, and to determine the mass and bulk density of the nucleus, key parameters in understanding how small bodies first formed in the solar nebula. A nucleus orbiter also provides the opportunity to sense the nucleus surface in preparation for more ambitious landing and sample return missions in the future. Additional information is contained in the original extended abstract.

  10. Physical role for the nucleus in cell migration.

    PubMed

    Fruleux, Antoine; Hawkins, Rhoda J

    2016-09-14

    Cell migration is important for the function of many eukaryotic cells. Recently the nucleus has been shown to play an important role in cell motility. After giving an overview of cell motility mechanisms we review what is currently known about the mechanical properties of the nucleus and the connections between it and the cytoskeleton. We also discuss connections to the extracellular matrix and mechanotransduction. We identify key physical roles of the nucleus in cell migration.

  11. Physical role for the nucleus in cell migration

    NASA Astrophysics Data System (ADS)

    Fruleux, Antoine; Hawkins, Rhoda J.

    2016-09-01

    Cell migration is important for the function of many eukaryotic cells. Recently the nucleus has been shown to play an important role in cell motility. After giving an overview of cell motility mechanisms we review what is currently known about the mechanical properties of the nucleus and the connections between it and the cytoskeleton. We also discuss connections to the extracellular matrix and mechanotransduction. We identify key physical roles of the nucleus in cell migration.

  12. Physical role for the nucleus in cell migration.

    PubMed

    Fruleux, Antoine; Hawkins, Rhoda J

    2016-09-14

    Cell migration is important for the function of many eukaryotic cells. Recently the nucleus has been shown to play an important role in cell motility. After giving an overview of cell motility mechanisms we review what is currently known about the mechanical properties of the nucleus and the connections between it and the cytoskeleton. We also discuss connections to the extracellular matrix and mechanotransduction. We identify key physical roles of the nucleus in cell migration. PMID:27406341

  13. Giant Resonances in the Alpha-Nucleus Interaction

    SciTech Connect

    Karpeshin, F. F.

    2010-04-30

    Tunneling of alpha particles through the Coulomb barrier for the source {sup 135}Pr nucleus is consecutively considered. The effect of sharp peaks arising in the case of coincidence of the alpha energy with that of a quasistationary state within the barrier is elucidated. Peaks' energy depend on the alpha-nucleus potential. They can give rise to 'anomalous' properties of some neutron resonances. The peaks can also be observed in the incoming alpha-nucleus channel. The method can be applied for solution of the reverse problem of the alpha-nucleus scattering.

  14. Nature of multiple-nucleus cluster galaxies

    SciTech Connect

    Merritt, D.

    1984-05-01

    In models for the evolution of galaxy clusters which include dynamical friction with the dark binding matter, the distribution of galaxies becomes more concentrated to the cluster center with time. In a cluster like Coma, this evolution could increase by a factor of approximately 3 the probability of finding a galaxy very close to the cluster center, without decreasing the typical velocity of such a galaxy significantly below the cluster mean. Such an enhancement is roughly what is needed to explain the large number of first-ranked cluster galaxies which are observed to have extra ''nuclei''; it is also consistent with the high velocities typically measured for these ''nuclei.'' Unlike the cannibalism model, this model predicts that the majority of multiple-nucleus systems are transient phenomena, and not galaxies in the process of merging.

  15. Nucleus of Comet P/Arend-Rigaux

    SciTech Connect

    Brooke, T.Y.; Knacke, R.F.

    1986-07-01

    Photometry data at 1-20 microns taken of Comet P/Arend-Rigaux are reported. The observations were carried out to test the possibility of observing the nuclei of low activity, nearly extinct comets at visible and IR wavelengths. The data were collected in February 1985 using the NASA 3 m IR telescope on Mauna Kea. The comet was at 1.67 AU heliocentric distance at the time. Attempts were made to detect rotation of the core on the bases of variations in the J, H and K light curves. The images obtained were those of a rotating nucleus with a radius of 4.0-6.2 km surrounded by a faint coma. The comet had a geometric albedo of 0.01-0.03 and a near-IR red slope that exhibited no evidence of the presence of ice. 32 references.

  16. Delta-nucleus dynamics: proceedings of symposium

    SciTech Connect

    Lee, T.S.H.; Geesaman, D.F.; Schiffer, J.P.

    1983-10-01

    The appreciation of the role in nuclear physics of the first excited state of the nucleon, the delta ..delta..(1232), has grown rapidly in the past decade. The delta resonance dominates nuclear reactions induced by intermediate energy pions, nucleons, and electromagnetic probes. It is also the most important non-nucleonic degree of freedom needed to resolve many fundamental problems encountered in the study of low-energy nuclear phenomena. Clearly, a new phase of nuclear physics has emerged and conventional thinking must be extended to account for this new dimension of nuclear dynamics. The most challenging problem we are facing is how a unified theory can be developed to describe ..delta..-nucleus dynamics at all energies. In exploring this new direction, it is important to have direct discussions among researchers with different viewpoints. Separate entries were prepared for the 49 papers presented. (WHK)

  17. Suprachiasmatic Nucleus: Cell Autonomy and Network Properties

    PubMed Central

    Welsh, David K.; Takahashi, Joseph S.; Kay, Steve A.

    2013-01-01

    The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals. Individual SCN neurons in dispersed culture can generate independent circadian oscillations of clock gene expression and neuronal firing. However, SCN rhythmicity depends on sufficient membrane depolarization and levels of intracellular calcium and cAMP. In the intact SCN, cellular oscillations are synchronized and reinforced by rhythmic synaptic input from other cells, resulting in a reproducible topographic pattern of distinct phases and amplitudes specified by SCN circuit organization. The SCN network synchronizes its component cellular oscillators, reinforces their oscillations, responds to light input by altering their phase distribution, increases their robustness to genetic perturbations, and enhances their precision. Thus, even though individual SCN neurons can be cell-autonomous circadian oscillators, neuronal network properties are integral to normal function of the SCN. PMID:20148688

  18. Analysis of Returned Comet Nucleus Samples

    NASA Technical Reports Server (NTRS)

    Chang, Sherwood (Compiler)

    1997-01-01

    This volume contains abstracts that have been accepted by the Program Committee for presentation at the Workshop on Analysis of Returned Comet Nucleus Samples, held in Milpitas, California, January 16-18, 1989. Conveners are Sherwood Chang (NASA Ames Research Center) and Larry Nyquist (NASA Johnson Space Center). Program Committee members are Thomas Ahrens (ex-officio; California Institute of Technology), Lou Allamandola (NASA Ames Research Center), David Blake (NASA Ames Research Center), Donald Brownlee (University of Washington, Seattle), Theodore E. Bunch (NASA Ames Research Center), Humberto Campins (Planetary Science Institute), Jeff Cuzzi (NASA Ames Research Center), Eberhard Griin (Max-Plank-Institut fiir Kemphysik), Martha Hanner (Jet Propulsion Laboratory), Alan Harris (Jet Propulsion Laboratory), John Kerrid-e (University of Califomia, Los Angeles), Yves Langevin (University of Paris), Gerhard Schwehm (ESTEC), and Paul Weissman (Jet Propulsion Laboratory). Logistics and administrative support for the workshop were provided by the Lunar and Planetary Institute Projects Office.

  19. Shaping the nucleus: factors and forces.

    PubMed

    Walters, Alison D; Bommakanti, Ananth; Cohen-Fix, Orna

    2012-09-01

    Take a look at a textbook illustration of a cell and you will immediately be able to locate the nucleus, which is often drawn as a spherical or ovoid shaped structure. But not all cells have such nuclei. In fact, some disease states are diagnosed by the presence of nuclei that have an abnormal shape or size. What defines nuclear shape and nuclear size, and how does nuclear geometry affect nuclear function? While the answer to the latter question remains largely unknown, significant progress has been made towards understanding the former. In this review, we provide an overview of the factors and forces that affect nuclear shape and size, discuss the relationship between ER structure and nuclear morphology, and speculate on the possible connection between nuclear size and its shape. We also note the many interesting questions that remain to be explored. PMID:22566057

  20. Nonlinear osmotic properties of the cell nucleus.

    PubMed

    Finan, John D; Chalut, Kevin J; Wax, Adam; Guilak, Farshid

    2009-03-01

    In the absence of active volume regulation processes, cell volume is inversely proportional to osmolarity, as predicted by the Boyle Van't Hoff relation. In this study, we tested the hypothesis that nuclear volume has a similar relationship with extracellular osmolarity in articular chondrocytes, cells that are exposed to changes in the osmotic environment in vivo. Furthermore, we explored the mechanism of the relationships between osmolarity and nuclear size and shape. Nuclear size was quantified using two independent techniques, confocal laser scanning microscopy and angle-resolved low coherence interferometry. Nuclear volume was osmotically sensitive but this relationship was not linear, showing a decline in the osmotic sensitivity in the hypo-osmotic range. Nuclear shape was also influenced by extracellular osmolarity, becoming smoother as the osmolarity decreased. The osmotically induced changes in nuclear size paralleled the changes in nuclear shape, suggesting that shape and volume are interdependent. The osmotic sensitivity of shape and volume persisted after disruption of the actin cytoskeleton. Isolated nuclei contracted in response to physiologic changes in macromolecule concentration but not in response to physiologic changes in ion concentration, suggesting solute size has an important influence on the osmotic pressurization of the nucleus. This finding in turn implies that the diffusion barrier that causes osmotic effects is not a semi-permeable membrane, but rather due to size constraints that prevent large solute molecules from entering small spaces in the nucleus. As nuclear morphology has been associated previously with cell phenotype, these findings may provide new insight into the role of mechanical and osmotic signals in regulating cell physiology. PMID:19107599

  1. Nonlinear osmotic properties of the cell nucleus

    PubMed Central

    Finan, John D.; Chalut, Kevin J.; Wax, Adam; Guilak, Farshid

    2009-01-01

    Summary In the absence of active volume regulation processes, cell volume is inversely proportional to osmolarity, as predicted by the Boyle Van’t Hoff relation. In this study, we tested the hypothesis that nuclear volume has a similar relationship with extracellular osmolarity in articular chondrocytes, cells that are exposed to changes in the osmotic environment in vivo, and furthermore, we explored the mechanism of the relationships between osmolarity and nuclear size and shape. Nuclear size was quantified using two independent techniques, confocal laser scanning microscopy and angle-resolved low coherence interferometry. Nuclear volume was osmotically-sensitive but this relationship was not linear, showing a decline in the osmotic sensitivity in the hypo-osmotic range. Nuclear shape was also influenced by extracellular osmolarity, becoming smoother as the osmolarity decreased. The osmotically-induced changes in nuclear size paralleled the changes in nuclear shape, suggesting that shape and volume are interdependent. The osmotic sensitivity of shape and volume persisted after disruption of the actin cytoskeleton. Isolated nuclei contracted in response to physiologic changes in macromolecule concentration but not in response to physiologic changes in ion concentration, suggesting solute size has an important influence on the osmotic pressurization of the nucleus. This finding in turn implies that the diffusion barrier that causes osmotic effects is not a semi-permeable membrane, but rather due to size constraints that prevent large solute molecules from entering small spaces in the nucleus. As nuclear morphology has been associated previously with cell phenotype, these findings may provide new insight into the role of mechanical and osmotic signals in regulating cell physiology. PMID:19107599

  2. Fluctuation analysis of relativistic nucleus-nucleus collisions in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1988-01-01

    An analytical technique was developed for identifying enhanced fluctuations in the angular distributions of secondary particles produced from relativistic nucleus-nucleus collisions. The method is applied under the assumption that the masses of the produced particles are small compared to their linear momenta. The importance of particles rests in the fact that enhanced fluctuations in the rapidity distributions is considered to be an experimental signal for the creation of the quark-gluon-plasma (QGP), a state of nuclear matter predicted from the quantum chromodynamics theory (QCD). In the approach, Monte Carlo simulations are employed that make use of a portable random member generator that allow the calculations to be performed on a desk-top computer. The method is illustrated with data taken from high altitude emulsion exposures and is immediately applicable to similar data from accelerator-based emulsion exposures.

  3. The suprachiasmatic nucleus-paraventricular nucleus interactions: a bridge to the neuroendocrine and autonomic nervous system.

    PubMed

    Buijs, R M; Hermes, M H; Kalsbeek, A

    1998-01-01

    Vasopressin (VP) is one of the principal neurotransmitters of the suprachiasmatic nucleus (SCN). By means of anatomical, physiological and electrophysiological techniques we have demonstrated that VP containing pathways from the SCN serve to affect neuroendocrine and 'autonomic' neurons in the paraventricular nucleus. By direct and indirect connections VP serves to inhibit corticosterone secretion, not only by affecting ACTH secretion but also by controlling the adrenal cortex via a neuronal route. Apart from controlling the pineal and adrenal, we also observed that the SCN is able to influence the heart. Subjecting rats or humans to light affects heart rate in a dose-dependent manner. These results suggest an important role for the SCN and VP in the SCN in the regulation of neuroendocrine and autonomic functions.

  4. Dynamical and Statistical Aspects in Nucleus--Nucleus Collisions Around the Fermi Energy

    NASA Astrophysics Data System (ADS)

    Tamain, B.; Assenard, M.; Auger, G.; Bacri, C. O.; Benlliure, J.; Bisquer, E.; Bocage, F.; Borderie, B.; Bougault, R.; Buchet, P.; Charvet, J. L.; Chbihi, A.; Colin, J.; Cussol, D.; Dayras, R.; Demeyer, A.; Dore, D.; Durand, D.; Eudes, P.; Frankland, J.; Galichet, E.; Genouin-Duhamel, E.; Gerlic, E.; Germain, M.; Gourio, D.; Guinet, D.; Gulminelli, F.; Lautesse, P.; Laville, J. L.; Lebrun, C.; Lecolley, J. F.; Lefevre, A.; Lefort, T.; Legrain, R.; Le Neindre, N.; Lopez, O.; Louvel, M.; Lukasik, J.; Marie, N.; Maskay, M.; Metivier, V.; Nalpas, L.; Nguyen, A.; Parlog, M.; Peter, J.; Plagnol, E.; Rahmani, A.; Reposeur, T.; Rivet, M. F.; Rosato, E.; Saint-Laurent, F.; Salou, S.; Squalli, M.; Steckmeyer, J. C.; Stern, M.; Tabacaru, T.; Tassan-Got, L.; Tirel, O.; Vient, E.; Volan, C.; Wieleczko, J. P.

    1998-01-01

    This contribution is devoted to two important aspects of intermediate energy nucleus-nucleus collisions: the competition of dynamical and statistical features, and the origin of the multifragmentation process. These two questions are discussed in focusing on Indra data. It turns out that most of collisions are binary and reminiscent of deep inelastic collisions observed at low energy. However, intermediate velocity emission is a clear signature of dynamical emission and establishes a link with the participant-spectator picture which applies at high bombarding energies. Multifragmentation is observed when the dissipated energy is large and it turns out that expansion occurs at least for central collisions, as it is expected if this phenomenum has a dynamical origin.

  5. Nuclear Effects in Neutrino-Nucleus Interactions and the MINERvA Neutrino Nucleus Scattering Program

    NASA Astrophysics Data System (ADS)

    Morfín, Jorge G.

    2011-09-01

    Nuclear effects of charged current deep inelastic neutrino-iron scattering have been studied in the frame-work of a χ2 analysis of parton distribution functions (PDFs)1. A set of iron PDFs have been extracted which are then used to compute xBj-dependent and Q2-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. Upon comparing our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for l±-iron scattering we find that, except for very high xBj, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering. The MINERvA neutrino-nucleus scattering experiment at Fermilab, will systematically study neutrino nuclear effects off of He, C, Fe and Pb for a more thorough A-dependent study of nuclear PDFs and these correction factors.

  6. Dielectron production in nucleus {plus} nucleus collisions at 1.05 GeV/nucleon

    SciTech Connect

    Porter, R.J.; Beedoe, S.; Bougteb, M.; Hallman, T.; Wang, Z.F.

    1996-06-28

    Measurements of dielectron production in heavy-ion collisions are valuable probes into the dynamics of the collision process. While the hadronic participants of the collision are subject to strong final state interactions, the coupling of the electron-positron pair to the collision medium is electromagnetic. Dielectrons, therefore suffer little rescattering leaving the interaction and can retain information about their production origins, probing even the early stages in the evolution of the collision. The DiLepton Spectrometer (DLS) collaboration`s original measurements of dielectron production established the existence of the signal at Bevalac energies. The 1992- 93 DLS measurements in nucleus+Nucleus collisions at a kinetic beam energy of 1.05 {ital GeV/nucleon} are the subject of this presentation.

  7. Cholinergic excitation from the pedunculopontine tegmental nucleus to the dentate nucleus in the rat.

    PubMed

    Vitale, F; Mattei, C; Capozzo, A; Pietrantoni, I; Mazzone, P; Scarnati, E

    2016-03-11

    In spite of the existence of pedunculopontine tegmental nucleus (PPTg) projections to cerebellar nuclei, their nature and functional role is unknown. These fibers may play a crucial role in postural control and may be involved in the beneficial effects induced by deep-brain stimulation (DBS) of brainstem structures in motor disorders. We investigated the effects of PPTg microstimulation on single-unit activity of dentate, fastigial and interpositus nuclei. The effects of PPTg stimulation were also studied in rats whose PPTg neurons were destroyed by ibotenic acid and subsequently subjected to iontophoretically applied cholinergic antagonists. The main response recorded in cerebellar nuclei was a short-latency (1.5-2 ms) and brief (13-15 ms) orthodromic activation. The dentate nucleus was the most responsive to PPTg stimulation. The destruction of PPTg cells reduced the occurrence of PPTg-evoked activation of dentate neurons, suggesting that the effect was due to stimulation of cell bodies and not due to fibers passing through or close to the PPTg. Application of cholinergic antagonists reduced or eliminated the PPTg-evoked response recorded in the dentate nucleus. The results show that excitation is exerted by the PPTg on the cerebellar nuclei, in particular on the dentate nucleus. Taken together with the reduction of nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in lesioned animals, the iontophoretic experiments suggest that the activation of dentate neurons is due to cholinergic fibers. These data help to explain the effects of DBS of the PPTg on axial motor disabilities in neurodegenerative disorders. PMID:26762800

  8. Measuring gene expression noise in early Drosophila embryos: nucleus-to-nucleus variability

    PubMed Central

    Golyandina, Nina E.; Holloway, David M.; Lopes, Francisco J.P.; Spirov, Alexander V.; Spirova, Ekaterina N.; Usevich, Konstantin D.

    2012-01-01

    In recent years the analysis of noise in gene expression has widely attracted the attention of experimentalists and theoreticians. Experimentally, the approaches based on in vivo fluorescent reporters in single cells appear to be straightforward and effective tools for bacteria and yeast. However, transferring these approaches to multicellular organisms presents many methodological problems. Here we describe our approach to measure between-nucleus variability (noise) in the primary morphogenetic gradient of Bicoid (Bcd) in the precellular blastoderm stage of fruit fly (Drosophila) embryos. The approach is based on the comparison of results for fixed immunostained embryos with observations of live embryos carrying fluorescent Bcd (Bcd-GFP). We measure the noise using two-dimensional Singular Spectrum Analysis (2D SSA). We have found that the nucleus-to-nucleus noise in Bcd intensity, both for live (Bcd-GFP) and for fixed immunstained embryos, tends to be signal-independent. In addition, the character of the noise is sensitive to the nuclear masking technique used to extract quantitative intensities. Further, the method of decomposing the raw quantitative expression data into a signal (expression surface) and residual noise affects the character of the residual noise. We find that careful masking of confocal images and use of appropriate computational tools to decompose raw expression data into trend and noise makes it possible to extract and study the biological noise of gene expression. PMID:22723811

  9. Measuring gene expression noise in early Drosophila embryos: nucleus-to-nucleus variability.

    PubMed

    Golyandina, Nina E; Holloway, David M; Lopes, Francisco J P; Spirov, Alexander V; Spirova, Ekaterina N; Usevich, Konstantin D

    2012-01-01

    In recent years the analysis of noise in gene expression has widely attracted the attention of experimentalists and theoreticians. Experimentally, the approaches based on in vivo fluorescent reporters in single cells appear to be straightforward and effective tools for bacteria and yeast. However, transferring these approaches to multicellular organisms presents many methodological problems. Here we describe our approach to measure between-nucleus variability (noise) in the primary morphogenetic gradient of Bicoid (Bcd) in the precellular blastoderm stage of fruit fly (Drosophila) embryos. The approach is based on the comparison of results for fixed immunostained embryos with observations of live embryos carrying fluorescent Bcd (Bcd-GFP). We measure the noise using two-dimensional Singular Spectrum Analysis (2D SSA). We have found that the nucleus-to-nucleus noise in Bcd intensity, both for live (Bcd-GFP) and for fixed immunstained embryos, tends to be signal-independent. In addition, the character of the noise is sensitive to the nuclear masking technique used to extract quantitative intensities. Further, the method of decomposing the raw quantitative expression data into a signal (expression surface) and residual noise affects the character of the residual noise. We find that careful masking of confocal images and use of appropriate computational tools to decompose raw expression data into trend and noise makes it possible to extract and study the biological noise of gene expression.

  10. Cytotoxicity of nucleus-targeting fluorescent gold nanoclusters.

    PubMed

    Zhao, Jing-Ya; Cui, Ran; Zhang, Zhi-Ling; Zhang, Mingxi; Xie, Zhi-Xiong; Pang, Dai-Wen

    2014-11-01

    Gold nanoclusters (AuNCs) with ultra small sizes and unique fluorescence properties have shown promising potential for imaging the nuclei of living cells. However, little is known regarding the potential cytotoxicity of AuNCs after they enter the cell nucleus. The aim of this study is to investigate whether and how nucleus-targeting AuNCs affect the normal functioning of cells. Highly stable, water-soluble and bright fluorescent Au25NCs (the core of each nanocluster is composed of 25 gold atoms) were synthesized. Specific targeting of Au25NCs to the cell nucleus was achieved by conjugating the TAT peptide to the Au25NCs. Cell viability, cell morphology, cell apoptosis/necrosis, reactive oxygen species (ROS) level and mitochondrial membrane potential examinations were performed on different cell lines exposed to the nucleus-targeting Au25NCs. We found that the nucleus-targeting Au25NCs caused cell apoptosis in a dose-dependent manner. A possible mechanism for the cytotoxicity of the nucleus-targeting Au25NCs was proposed as follows: the nucleus-targeting Au25NCs induce the production of ROS, resulting in the oxidative degradation of mitochondrial components, in turn leading to apoptosis via a mitochondrial damage pathway. This work facilitates a better understanding of the toxicity of AuNCs, especially nucleus-targeting AuNCs.

  11. The Confined Hydrogen Atom with a Moving Nucleus

    ERIC Educational Resources Information Center

    Fernandez, Francisco M.

    2010-01-01

    We study the hydrogen atom confined to a spherical box with impenetrable walls but, unlike earlier pedagogical articles on the subject, we assume that the nucleus also moves. We obtain the ground-state energy approximately by means of first-order perturbation theory and show that it is greater than that for the case in which the nucleus is clamped…

  12. Glutamatergic projection from the nucleus incertus to the septohippocampal system.

    PubMed

    Cervera-Ferri, Ana; Rahmani, Yasamin; Martínez-Bellver, Sergio; Teruel-Martí, Vicent; Martínez-Ricós, Joana

    2012-05-31

    Recent findings support a relevant role of the nucleus incertus in the control of the hippocampal activity through the modulation of theta rhythm. Previous studies from our group have shown that this nucleus is a critical relay between reticularis pontis oralis and the medial septum/diagonal band, regarded as the main activator and the pacemaker of the hippocampal oscillations, respectively. Besides, the nucleus incertus is highly linked to activated states related to the arousal response. The neurotransmission of the nucleus incertus, however, remains uncertain. Only GABA and the neuromodulator relaxin 3 are usually considered to be involved in its contribution to the septohippocampal system. In this work, we have analyzed the existence of an excitatory projection from the nucleus incertus to the medial septum. We have found a group of glutamatergic neurons in the nucleus incertus projecting to the medial septum. Moreover, we were able to describe a segregated distribution of calbindin and calretinin neurons. While calretinin expression was restricted to the nucleus incertus pars compacta, calbindin positive neurons where observed both in the pars dissipata and the pars compacta of the nucleus. The present work provides innovative data supporting an excitatory component in the pontoseptal pathway.

  13. Mission CaMKIIγ: shuttle calmodulin from membrane to nucleus.

    PubMed

    Malik, Zulfiqar A; Stein, Ivar S; Navedo, Manuel F; Hell, Johannes W

    2014-10-01

    Neuronal plasticity depends on plasma membrane Ca(2+) influx, resulting in activity-dependent gene transcription. Calmodulin (CaM) activated by Ca(2+) initiates the nuclear events, but how CaM makes its way to the nucleus has remained elusive. Ma et al. now show that CaMKIIγ transports CaM from cell surface Ca(2+) channels to the nucleus.

  14. Nucleon emission via electromagnetic excitation in relativistic nucleus-nucleus collisions: Re-analysis of the Weizsacker-Williams method

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1989-01-01

    Previous analyses of the comparison of Weizsacker-Williams (WW) theory to experiment for nucleon emission via electromagnetic (EM) excitations in nucleus-nucleus collisions were not definitive because of different assumptions concerning the value of the minimum impact parameter. This situation is corrected by providing criteria that allows definitive statements to be made concerning agreement or disagreement between WW theory and experiment.

  15. Control of nucleus accumbens activity with neurofeedback.

    PubMed

    Greer, Stephanie M; Trujillo, Andrew J; Glover, Gary H; Knutson, Brian

    2014-08-01

    The nucleus accumbens (NAcc) plays critical roles in healthy motivation and learning, as well as in psychiatric disorders (including schizophrenia and attention deficit hyperactivity disorder). Thus, techniques that confer control of NAcc activity might inspire new therapeutic interventions. By providing second-to-second temporal resolution of activity in small subcortical regions, functional magnetic resonance imaging (fMRI) can resolve online changes in NAcc activity, which can then be presented as "neurofeedback." In an fMRI-based neurofeedback experiment designed to elicit NAcc activity, we found that subjects could increase their own NAcc activity, and that display of neurofeedback significantly enhanced their ability to do so. Subjects were not as capable of decreasing their NAcc activity, however, and enhanced control did not persist after subsequent removal of neurofeedback. Further analyses suggested that individuals who recruited positive aroused affect were better able to increase NAcc activity in response to neurofeedback, and that NAcc neurofeedback also elicited functionally correlated activity in the medial prefrontal cortex. Together, these findings suggest that humans can modulate their own NAcc activity and that fMRI-based neurofeedback may augment their efforts. The observed association between positive arousal and effective NAcc control further supports an anticipatory affect account of NAcc function.

  16. Comparing Realistic Subthalamic Nucleus Neuron Models

    NASA Astrophysics Data System (ADS)

    Njap, Felix; Claussen, Jens C.; Moser, Andreas; Hofmann, Ulrich G.

    2011-06-01

    The mechanism of action of clinically effective electrical high frequency stimulation is still under debate. However, recent evidence points at the specific activation of GABA-ergic ion channels. Using a computational approach, we analyze temporal properties of the spike trains emitted by biologically realistic neurons of the subthalamic nucleus (STN) as a function of GABA-ergic synaptic input conductances. Our contribution is based on a model proposed by Rubin and Terman and exhibits a wide variety of different firing patterns, silent, low spiking, moderate spiking and intense spiking activity. We observed that most of the cells in our network turn to silent mode when we increase the GABAA input conductance above the threshold of 3.75 mS/cm2. On the other hand, insignificant changes in firing activity are observed when the input conductance is low or close to zero. We thus reproduce Rubin's model with vanishing synaptic conductances. To quantitatively compare spike trains from the original model with the modified model at different conductance levels, we apply four different (dis)similarity measures between them. We observe that Mahalanobis distance, Victor-Purpura metric, and Interspike Interval distribution are sensitive to different firing regimes, whereas Mutual Information seems undiscriminative for these functional changes.

  17. Calretinin Neurons in the Rat Suprachiasmatic Nucleus.

    PubMed

    Moore, Robert Y

    2016-08-01

    The hypothalamic suprachiasmatic nucleus (SCN), a circadian pacemaker, is present in all mammalian brains. It has a complex organization of peptide-containing neurons that is similar among species, but calcium-binding proteins are expressed variably. Neurons containing calretinin have been described in the SCN in a number of species but not with association to circadian function. The objective of the present study is to characterize a calretinin neuron (CAR) group in the rat anterior hypothalamus anatomically and functionally with a detailed description of its location and a quantitative analysis of neuronal calretinin immunoreactivity at 3 times of day, 0600, 1400, and 1900 h, from animals in either light-dark or constant dark conditions. CAR neurons occupy a region in the dorsal and lateral SCN with a circadian rhythm in CAR immunoreactivity with a peak at 0600 h and a rhythm in cytoplasmic CAR distribution with a peak at 1400 h. CAR neurons should be viewed as an anatomical and functional component of the rat SCN that expands the definition from observations with cell stains. CAR neurons are likely to modulate temporal regulation of calcium in synaptic transmission.

  18. Inside a plant nucleus: discovering the proteins.

    PubMed

    Petrovská, Beáta; Šebela, Marek; Doležel, Jaroslav

    2015-03-01

    Nuclear proteins are a vital component of eukaryotic cell nuclei and have a profound effect on the way in which genetic information is stored, expressed, replicated, repaired, and transmitted to daughter cells and progeny. Because of the plethora of functions, nuclear proteins represent the most abundant components of cell nuclei in all eukaryotes. However, while the plant genome is well understood at the DNA level, information on plant nuclear proteins remains scarce, perhaps with the exception of histones and a few other proteins. This lack of knowledge hampers efforts to understand how the plant genome is organized in the nucleus and how it functions. This review focuses on the current state of the art of the analysis of the plant nuclear proteome. Previous proteome studies have generally been designed to search for proteins involved in plant response to various forms of stress or to identify rather a modest number of proteins. Thus, there is a need for more comprehensive and systematic studies of proteins in the nuclei obtained at individual phases of the cell cycle, or isolated from various tissue types and stages of cell and tissue differentiation. All this in combination with protein structure, predicted function, and physical localization in 3D nuclear space could provide much needed progress in our understanding of the plant nuclear proteome and its role in plant genome organization and function.

  19. Ultrasonic evoked responses in rat cochlear nucleus

    PubMed Central

    Du, Yi; Ping, Junli; Li, Nanxin; Wu, Xihong; Li, Liang; Galbraith, Gary

    2009-01-01

    Numerous studies have reported auditory brainstem responses evoked by stimuli within the “normal” hearing range of rats, with maximum sensitivity peaking around 16 kHz. Yet rats also emit and respond to sounds in the ultrasonic (US) frequency range (30-100 kHz). However very few electrophysiological studies have recorded auditory brainstem responses using US stimuli, and none have exceeded 70 kHz. We report here short-latency (1-3 ms) evoked potentials recorded in rat cochlear nucleus (CN) to US stimuli ranging from 40-90 kHz. Robust responses were recorded in 33 of 36 CN recording sites to stimuli ranging from 40-60 kHz; and twenty-eight of these sites continued to yield well defined responses out to 90 kHz. Latencies systematically increased and overall amplitudes decreased with increasing US frequency. Amplitudes differed significantly in the three CN subnuclei, being largest in posterior-ventral (PVCN) and smallest in anterior-ventral (AVCN). The fact that well defined responses can be recorded to stimuli as high as 90 kHz significantly extends the recorded upper frequency range of neural activity in the brainstem auditory pathway of the rat. These evoked potential results agree with the well documented behavioral repertoire of rats in the US frequency range. PMID:17803975

  20. SUNrises on the International Plant Nucleus Consortium

    PubMed Central

    Graumann, Katja; Bass, Hank W.; Parry, Geraint

    2013-01-01

    The nuclear periphery is a dynamic, structured environment, whose precise functions are essential for global processes—from nuclear, to cellular, to organismal. Its main components—the nuclear envelope (NE) with inner and outer nuclear membranes (INM and ONM), nuclear pore complexes (NPC), associated cytoskeletal and nucleoskeletal components as well as chromatin are conserved across eukaryotes (Fig. 1). In metazoans in particular, the structure and functions of nuclear periphery components are intensely researched partly because of their involvement in various human diseases. While far less is known about these in plants, the last few years have seen a significant increase in research activity in this area. Plant biologists are not only catching up with the animal field, but recent findings are pushing our advances in this field globally. In recognition of this developing field, the Annual Society of Experimental Biology Meeting in Salzburg kindly hosted a session co-organized by Katja Graumann and David E. Evans (Oxford Brookes University) highlighting new insights into plant nuclear envelope proteins and their interactions. This session brought together leading researchers with expertise in topics such as epigenetics, meiosis, nuclear pore structure and functions, nucleoskeleton and nuclear envelope composition. An open and friendly exchange of ideas was fundamental to the success of the meeting, which resulted in founding the International Plant Nucleus Consortium. This review highlights new developments in plant nuclear envelope research presented at the conference and their importance for the wider understanding of metazoan, yeast and plant nuclear envelope functions and properties. PMID:23324458

  1. Functional network inference of the suprachiasmatic nucleus.

    PubMed

    Abel, John H; Meeker, Kirsten; Granados-Fuentes, Daniel; St John, Peter C; Wang, Thomas J; Bales, Benjamin B; Doyle, Francis J; Herzog, Erik D; Petzold, Linda R

    2016-04-19

    In the mammalian suprachiasmatic nucleus (SCN), noisy cellular oscillators communicate within a neuronal network to generate precise system-wide circadian rhythms. Although the intracellular genetic oscillator and intercellular biochemical coupling mechanisms have been examined previously, the network topology driving synchronization of the SCN has not been elucidated. This network has been particularly challenging to probe, due to its oscillatory components and slow coupling timescale. In this work, we investigated the SCN network at a single-cell resolution through a chemically induced desynchronization. We then inferred functional connections in the SCN by applying the maximal information coefficient statistic to bioluminescence reporter data from individual neurons while they resynchronized their circadian cycling. Our results demonstrate that the functional network of circadian cells associated with resynchronization has small-world characteristics, with a node degree distribution that is exponential. We show that hubs of this small-world network are preferentially located in the central SCN, with sparsely connected shells surrounding these cores. Finally, we used two computational models of circadian neurons to validate our predictions of network structure.

  2. Functional network inference of the suprachiasmatic nucleus.

    PubMed

    Abel, John H; Meeker, Kirsten; Granados-Fuentes, Daniel; St John, Peter C; Wang, Thomas J; Bales, Benjamin B; Doyle, Francis J; Herzog, Erik D; Petzold, Linda R

    2016-04-19

    In the mammalian suprachiasmatic nucleus (SCN), noisy cellular oscillators communicate within a neuronal network to generate precise system-wide circadian rhythms. Although the intracellular genetic oscillator and intercellular biochemical coupling mechanisms have been examined previously, the network topology driving synchronization of the SCN has not been elucidated. This network has been particularly challenging to probe, due to its oscillatory components and slow coupling timescale. In this work, we investigated the SCN network at a single-cell resolution through a chemically induced desynchronization. We then inferred functional connections in the SCN by applying the maximal information coefficient statistic to bioluminescence reporter data from individual neurons while they resynchronized their circadian cycling. Our results demonstrate that the functional network of circadian cells associated with resynchronization has small-world characteristics, with a node degree distribution that is exponential. We show that hubs of this small-world network are preferentially located in the central SCN, with sparsely connected shells surrounding these cores. Finally, we used two computational models of circadian neurons to validate our predictions of network structure. PMID:27044085

  3. Control of nucleus accumbens activity with neurofeedback

    PubMed Central

    Greer, Stephanie M.; Trujillo, Andrew J.; Glover, Gary H.; Knutson, Brian

    2014-01-01

    The nucleus accumbens (NAcc) plays critical roles in healthy motivation and learning, as well as in psychiatric disorders (including schizophrenia and attention deficit hyperactivity disorder). Thus, techniques that confer control of NAcc activity might inspire new therapeutic interventions. By providing second-to-second temporal resolution of activity in small subcortical regions, functional magnetic resonance imaging (fMRI) can resolve online changes in NAcc activity, which can then be presented as “neurofeedback.” In an fMRI-based neurofeedback experiment designed to elicit NAcc activity, we found that subjects could increase their own NAcc activity, and that display of neurofeedback significantly enhanced their ability to do so. Subjects were not as capable of decreasing their NAcc activity, however, and enhanced control did not persist after subsequent removal of neurofeedback. Further analyses suggested that individuals who recruited positive arousal affect were better able to increase NAcc activity in response to neurofeedback, and that NAcc neurofeedback also elicited functionally correlated activity in the medial prefrontal cortex. Together, these findings suggest that humans can modulate their own NAcc activity and that fMRI-based neurofeedback may augment their efforts. The observed association between positive arousal and effective NAcc control further supports an anticipatory affect account of NAcc function. PMID:24705203

  4. Angiotensin receptor binding and pressor effects in cat subretrofacial nucleus

    SciTech Connect

    Allen, A.M.; Dampney, R.A.L.; Mendelsohn, F.A.O. Univ. of Sydney )

    1988-11-01

    Central administration of angiotensin II (ANG II) increases arterial blood pressure via increased sympathetic activity. The authors have examined the possibility that one site of action of ANG II is the subretrofacial (SRF) nucleus in the rostral ventrolateral medulla, since this nucleus is known to play a critical role in the tonic and phasic control of arterial pressure. In vitro autoradiography, employing {sup 125}I-labeled (Sar{sup 1}, Ile{sup 8})ANG II as radioligand, was used to localize binding sites for ANG-II in the cat ventrolateral medulla. A high density of ANG II-receptor binding sites was found confined to the SRF nucleus. In a second group of experiments in anesthetized cats, microinjections of ANG II, in doses ranging from 10 to 50 pmol, were made into histologically identified sites within and outside the SRF nucleus. Microinjections into the nucleus resulted in a dose-dependent increase in arterial pressure, which was abolished by systemic administration of the ganglion-blocking drug hexamethonium bromide. In contrast, microinjections just outside the SRF nucleus had no effect on arterial pressure. It is concluded that activation of ANG II-receptor binding sites within the SRF nucleus leads to an increase in arterial pressure via increased sympathetic efferent activity.

  5. The Suprachiasmatic Nucleus Modulates the Sensitivity of Arcuate Nucleus to Hypoglycemia in the Male Rat.

    PubMed

    Herrera-Moro Chao, D; León-Mercado, L; Foppen, E; Guzmán-Ruiz, M; Basualdo, M C; Escobar, C; Buijs, R M

    2016-09-01

    The suprachiasmatic nucleus (SCN) and arcuate nucleus (ARC) have reciprocal connections; catabolic metabolic information activates the ARC and inhibits SCN neuronal activity. Little is known about the influence of the SCN on the ARC. Here, we investigated whether the SCN modulated the sensitivity of the ARC to catabolic metabolic conditions. ARC neuronal activity, as determined by c-Fos immunoreactivity, was increased after a hypoglycemic stimulus by 2-deoxyglucose (2DG). The highest ARC neuronal activity after 2DG was found at the end of the light period (zeitgeber 11, ZT11) with a lower activity in the beginning of the light period (zeitgeber 2, ZT2), suggesting the involvement of the SCN. The higher activation of ARC neurons after 2DG at ZT11 was associated with higher 2DG induced blood glucose levels as compared with ZT2. Unilateral SCN-lesioned animals, gave a mainly ipsilateral activation of ARC neurons at the lesioned side, suggesting an inhibitory role of the SCN on ARC neurons. The 2DG-induced counterregulatory glucose response correlated with increased ARC neuronal activity and was significantly higher in unilateral SCN-lesioned animals. Finally, the ARC as site where 2DG may, at least partly, induce a counterregulatory response was confirmed by local microdialysis of 2DG. 2DG administration in the ARC produced a higher increase in circulating glucose compared with 2DG administration in surrounding areas such as the ventromedial nucleus of the hypothalamus (VMH). We conclude that the SCN uses neuronal pathways to the ARC to gate sensory metabolic information to the brain, regulating ARC glucose sensitivity and counterregulatory responses to hypoglycemic conditions. PMID:27429160

  6. The Suprachiasmatic Nucleus Modulates the Sensitivity of Arcuate Nucleus to Hypoglycemia in the Male Rat.

    PubMed

    Herrera-Moro Chao, D; León-Mercado, L; Foppen, E; Guzmán-Ruiz, M; Basualdo, M C; Escobar, C; Buijs, R M

    2016-09-01

    The suprachiasmatic nucleus (SCN) and arcuate nucleus (ARC) have reciprocal connections; catabolic metabolic information activates the ARC and inhibits SCN neuronal activity. Little is known about the influence of the SCN on the ARC. Here, we investigated whether the SCN modulated the sensitivity of the ARC to catabolic metabolic conditions. ARC neuronal activity, as determined by c-Fos immunoreactivity, was increased after a hypoglycemic stimulus by 2-deoxyglucose (2DG). The highest ARC neuronal activity after 2DG was found at the end of the light period (zeitgeber 11, ZT11) with a lower activity in the beginning of the light period (zeitgeber 2, ZT2), suggesting the involvement of the SCN. The higher activation of ARC neurons after 2DG at ZT11 was associated with higher 2DG induced blood glucose levels as compared with ZT2. Unilateral SCN-lesioned animals, gave a mainly ipsilateral activation of ARC neurons at the lesioned side, suggesting an inhibitory role of the SCN on ARC neurons. The 2DG-induced counterregulatory glucose response correlated with increased ARC neuronal activity and was significantly higher in unilateral SCN-lesioned animals. Finally, the ARC as site where 2DG may, at least partly, induce a counterregulatory response was confirmed by local microdialysis of 2DG. 2DG administration in the ARC produced a higher increase in circulating glucose compared with 2DG administration in surrounding areas such as the ventromedial nucleus of the hypothalamus (VMH). We conclude that the SCN uses neuronal pathways to the ARC to gate sensory metabolic information to the brain, regulating ARC glucose sensitivity and counterregulatory responses to hypoglycemic conditions.

  7. Multiple pion and kaon production in high energy nucleus-nucleus collisions: measurements versus specific models

    NASA Astrophysics Data System (ADS)

    Guptaroy, P.; de, Bh.; Bhattacharyya, S.; Bhattacharyya, D. P.

    The pion and kaon rapidity densities and the nature of kaon-pion ratios offer two very prominent and crucial physical observables on which modestly sufficient data for heavy nucleus collisions are available to date. In the light of two sets of models - one purely phenomenological and the other with a modest degree of a dynamical basis - we try to examine the state of agreement between calculations and experimental results obtainable from the past and the latest measurements. Impact and implications of all these would also finally be spelt out.

  8. Ice nucleus activity measurements of solid rocket motor exhaust particles

    NASA Technical Reports Server (NTRS)

    Keller, V. W. (Compiler)

    1986-01-01

    The ice Nucleus activity of exhaust particles generated from combustion of Space Shuttle propellant in small rocket motors has been measured. The activity at -20 C was substantially lower than that of aerosols generated by unpressurized combustion of propellant samples in previous studies. The activity decays rapidly with time and is decreased further in the presence of moist air. These tests corroborate the low effectivity ice nucleus measurement results obtained in the exhaust ground cloud of the Space Shuttle. Such low ice nucleus activity implies that Space Shuttle induced inadvertent weather modification via an ice phase process is extremely unlikely.

  9. Quarkonium-nucleus bound states from lattice QCD

    SciTech Connect

    Beane, S.  R.; Chang, E.; Cohen, S.  D.; Detmold, W.; Lin, H. -W.; Orginos, K.; Parreño, A.; Savage, M.  J.

    2015-06-11

    Quarkonium-nucleus systems are composed of two interacting hadronic states without common valence quarks, which interact primarily through multi-gluon exchanges, realizing a color van der Waals force. We present lattice QCD calculations of the interactions of strange and charm quarkonia with light nuclei. Both the strangeonium-nucleus and charmonium-nucleus systems are found to be relatively deeply bound when the masses of the three light quarks are set equal to that of the physical strange quark. Extrapolation of these results to the physical light-quark masses suggests that the binding energy of charmonium to nuclear matter is B < 40 MeV.

  10. Determination of electron-nucleus collisions geometry with forward neutrons

    SciTech Connect

    Zheng, L.; Aschenauer, E.; Lee, J. H.

    2014-12-29

    There are a large number of physics programs one can explore in electron-nucleus collisions at a future electron-ion collider. Collision geometry is very important in these studies, while the measurement for an event-by-event geometric control is rarely discussed in the prior deep-inelastic scattering experiments off a nucleus. This paper seeks to provide some detailed studies on the potential of tagging collision geometries through forward neutron multiplicity measurements with a zero degree calorimeter. As a result, this type of geometry handle, if achieved, can be extremely beneficial in constraining nuclear effects for the electron-nucleus program at an electron-ion collider.

  11. Smallest Black Hole in Galactic Nucleus Detected

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-08-01

    A team of astronomers have reported the detection of the smallest black hole (BH) ever observed in a galactic nucleus. The BH is hosted in the center of dwarf galaxy RGG 118, and it weighs in at 50,000 solar masses, according to observations made by Vivienne Baldassare of University of Michigan and her collaborators. Small Discoveries: Why is the discovery of a small nuclear BH important? Some open questions that this could help answer are: - Do the very smallest dwarf galaxies have BHs at their centers too? Though we believe that there's a giant BH at the center of every galaxy, we aren't sure how far down the size scale this holds true. - What is the formation mechanism for BHs at the center of galaxies? - What's the behavior of the M-sigma relation at the low-mass end? The M-sigma relation is an observed correlation between the mass of a galaxy's central BH and the velocity dispersion of the stars in the galaxy. This relation is incredibly useful for determining properties of distant BHs and their galaxies empirically, but little data is available to constrain the low-mass end of the relation. M-sigma relation, plotting systems with dynamically-measured black hole masses. RGG 118 is plotted as the pink star. The solid and dashed lines represent various determinations of scaling relations. Credit: Baldassare et al. 2015. Identifying a Black Hole: RGG 118 was identified as a candidate host for an accreting, nuclear BH from the catalog of dwarf galaxies observed in the Sloan Digital Sky Survey. Baldassare and her team followed up with high-resolution spectroscopy from the Clay telescope in Chile and Chandra x-ray observations. Using these observations, the team determined that RGG 118 plays host to a massive BH at its center based on three clues: 1) narrow emission line ratios, which is a signature of accretion onto a massive BH, 2) the presence of broad emission lines, indicating that gas is rotating around a central BH, and 3) the existence of an X-ray point

  12. Projections of nucleus angularis and nucleus laminaris to the lateral lemniscal nuclear complex of the barn owl.

    PubMed

    Takahashi, T T; Konishi, M

    1988-08-01

    Interaural phase and intensity are cues by which the barn owl determines, respectively, the azimuth and elevation of a sound source. Physiological studies indicate that phase and intensity are processed independently in the auditory brainstem of the barn owl. The phases of spectral components of a sound are encoded in nucleus magnocellularis (NM), one of the two cochlear nuclei. NM projects solely and bilaterally to nucleus laminaris (NL), wherein interaural phase difference is computed. The other cochlear nucleus, nucleus angularis (NA), encodes the amplitudes of spectral components of sounds. We report here the projections of NA and NL to the lateral lemniscal nuclei of the barn owl. The lateral lemniscal complex comprises nucleus olivaris superior (SO); nucleus lemnisci lateralis, pars ventralis (LLv); and nucleus ventralis lemnisci lateralis (VLV). At caudal levels, VLV may be divided into a posterior (VLVp) and an anterior (VLVa) subdivision on cytoarchitectonic grounds. At rostral levels, the cytoarchitectural differences diminish and the boundaries between the two subdivisions become obscured. Likewise, our data from anterograde tracing studies suggest that at caudal levels the terminal fields of NA and NL remain confined to VLVp and VLVa, respectively. They merge, however, at rostral levels. The data also suggest that NL projects to the medial portion of the ipsilateral SO and that NA projects bilaterally to all parts of SO and LLv. Studies with the retrograde transport of horseradish peroxidase confirm these projections. PMID:2463287

  13. Observation of the antimatter helium-4 nucleus.

    PubMed

    2011-05-19

    High-energy nuclear collisions create an energy density similar to that of the Universe microseconds after the Big Bang; in both cases, matter and antimatter are formed with comparable abundance. However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high-energy accelerator of heavy nuclei provides an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus (4He), also known as the anti-α (α), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the α-particle was identified a century ago by Rutherford and is present in cosmic radiation at the ten per cent level. Antimatter nuclei with B < -1 have been observed only as rare products of interactions at particle accelerators, where the rate of antinucleus production in high-energy collisions decreases by a factor of about 1,000 with each additional antinucleon. Here we report the observation of 4He, the heaviest observed antinucleus to date. In total, 18 4He counts were detected at the STAR experiment at the Relativistic Heavy Ion Collider (RHIC; ref. 6) in 10(9) recorded gold-on-gold (Au+Au) collisions at centre-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon pair. The yield is consistent with expectations from thermodynamic and coalescent nucleosynthesis models, providing an indication of the production rate of even heavier antimatter nuclei and a benchmark for possible future observations of 4He in cosmic radiation.

  14. Observation of the antimatter helium-4 nucleus.

    PubMed

    2011-05-19

    High-energy nuclear collisions create an energy density similar to that of the Universe microseconds after the Big Bang; in both cases, matter and antimatter are formed with comparable abundance. However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high-energy accelerator of heavy nuclei provides an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus (4He), also known as the anti-α (α), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the α-particle was identified a century ago by Rutherford and is present in cosmic radiation at the ten per cent level. Antimatter nuclei with B < -1 have been observed only as rare products of interactions at particle accelerators, where the rate of antinucleus production in high-energy collisions decreases by a factor of about 1,000 with each additional antinucleon. Here we report the observation of 4He, the heaviest observed antinucleus to date. In total, 18 4He counts were detected at the STAR experiment at the Relativistic Heavy Ion Collider (RHIC; ref. 6) in 10(9) recorded gold-on-gold (Au+Au) collisions at centre-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon pair. The yield is consistent with expectations from thermodynamic and coalescent nucleosynthesis models, providing an indication of the production rate of even heavier antimatter nuclei and a benchmark for possible future observations of 4He in cosmic radiation. PMID:21516103

  15. Nucleus accumbens invulnerability to methamphetamine neurotoxicity.

    PubMed

    Kuhn, Donald M; Angoa-Pérez, Mariana; Thomas, David M

    2011-01-01

    Methamphetamine (Meth) is a neurotoxic drug of abuse that damages neurons and nerve endings throughout the central nervous system. Emerging studies of human Meth addicts using both postmortem analyses of brain tissue and noninvasive imaging studies of intact brains have confirmed that Meth causes persistent structural abnormalities. Animal and human studies have also defined a number of significant functional problems and comorbid psychiatric disorders associated with long-term Meth abuse. This review summarizes the salient features of Meth-induced neurotoxicity with a focus on the dopamine (DA) neuronal system. DA nerve endings in the caudate-putamen (CPu) are damaged by Meth in a highly delimited manner. Even within the CPu, damage is remarkably heterogeneous, with ventral and lateral aspects showing the greatest deficits. The nucleus accumbens (NAc) is largely spared the damage that accompanies binge Meth intoxication, but relatively subtle changes in the disposition of DA in its nerve endings can lead to dramatic increases in Meth-induced toxicity in the CPu and overcome the normal resistance of the NAc to damage. In contrast to the CPu, where DA neuronal deficiencies are persistent, alterations in the NAc show a partial recovery. Animal models have been indispensable in studies of the causes and consequences of Meth neurotoxicity and in the development of new therapies. This research has shown that increases in cytoplasmic DA dramatically broaden the neurotoxic profile of Meth to include brain structures not normally targeted for damage. The resistance of the NAc to Meth-induced neurotoxicity and its ability to recover reveal a fundamentally different neuroplasticity by comparison to the CPu. Recruitment of the NAc as a target of Meth neurotoxicity by alterations in DA homeostasis is significant in light of the numerous important roles played by this brain structure.

  16. Stimulation of the Subthalamic Nucleus and Impulsivity

    PubMed Central

    Ballanger, Benedicte; van Eimeren, Thilo; Moro, Elena; Lozano, Andres M.; Hamani, Clement; Boulinguez, Philippe; Pellecchia, Giovanna; Houle, Sylvain; Poon, Yu Yan; Lang, Anthony E.; Strafella, Antonio P.

    2010-01-01

    Objective In Parkinson disease (PD) patients, deep brain stimulation (DBS) of the subthalamic nucleus (STN) may contribute to certain impulsive behavior during high-conflict decisions. A neurocomputational model of the basal ganglia has recently been proposed that suggests this behavioral aspect may be related to the role played by the STN in relaying a “hold your horses” signal intended to allow more time to settle on the best option. The aim of the present study was 2-fold: 1) to extend these observations by providing evidence that the STN may influence and prevent the execution of any response even during low-conflict decisions; and 2) to identify the neural correlates of this effect. Methods We measured regional cerebral blood flow during a Go/NoGo and a control (Go) task to study the motor improvement and response inhibition deficits associated with STN-DBS in patients with PD. Results Although it improved Unified Parkinson Disease Rating Scale motor ratings and induced a global decrease in reaction time during task performance, STN-DBS impaired response inhibition, as revealed by an increase in commission errors in NoGo trials. These behavioral effects were accompanied by changes in synaptic activity consisting of a reduced activation in the cortical networks responsible for reactive and proactive response inhibition. Interpretation The present results suggest that although it improves motor functions in PD patients, modulation of STN hyperactivity with DBS may tend at the same time to favor the appearance of impulsive behavior by acting on the gating mechanism involved in response initiation. PMID:20035509

  17. Multiple-scattering effects in nucleus-nucleus reactions with Glauber theory

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Shinya; Ebata, Shuichiro; Horiuchi, Wataru; Kimura, Masaaki

    2014-09-01

    A study of new unstable nuclei has become possible in new radioactive beam facilities. In order to understand the relationship between reaction observables and nuclear structure, we need reaction theory which exactly reflects the nuclear structure. The Glauber theory is a powerful tool of analyzing high energy nuclear reactions. The theory describes the multiple scattering processes, whereas the optical limit approximation (OLA), which is widely used, ignores those processes. Those effects are expected to play an important role in the nuclear collision involving unstable nuclei (see for example Phys. Rev. C 54, 1843 (1996)). Here we apply the Glauber theory to nucleus-nucleus reactions. The wave functions are generated by the Skyrme-Hartree-Fock method and are expressed in a Slater determinant that allows us to evaluate the complete Glauber amplitude easily. We calculate total reaction cross sections, elastic cross sections and differential elastic cross sections for 16~24O, 40~70Ca, 56,58Ni, 100~140Sn, 190~214Pb on proton, 4He, 12C targets and compare with experimental data. The Glauber theory gives much better description than the OLA, especially at larger scattering angles.

  18. Statistical analysis of secondary particle distributions in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1987-01-01

    The use is described of several statistical techniques to characterize structure in the angular distributions of secondary particles from nucleus-nucleus collisions in the energy range 24 to 61 GeV/nucleon. The objective of this work was to determine whether there are correlations between emitted particle intensity and angle that may be used to support the existence of the quark gluon plasma. The techniques include chi-square null hypothesis tests, the method of discrete Fourier transform analysis, and fluctuation analysis. We have also used the method of composite unit vectors to test for azimuthal asymmetry in a data set of 63 JACEE-3 events. Each method is presented in a manner that provides the reader with some practical detail regarding its application. Of those events with relatively high statistics, Fe approaches 0 at 55 GeV/nucleon was found to possess an azimuthal distribution with a highly non-random structure. No evidence of non-statistical fluctuations was found in the pseudo-rapidity distributions of the events studied. It is seen that the most effective application of these methods relies upon the availability of many events or single events that possess very high multiplicities.

  19. Major diencephalic inputs to the hippocampus: supramammillary nucleus and nucleus reuniens. Circuitry and function

    PubMed Central

    Vertes, Robert P.

    2016-01-01

    The hippocampus receives two major external inputs from the diencephalon, that is, from the supramammillary nucleus (SUM) and nucleus reuniens (RE) of the midline thalamus. These two afferents systems project to separate, nonoverlapping, regions of the hippocampus. Specifically, the SUM distributes to the dentate gyrus (DG) and to CA2 of the dorsal and ventral hippocampus, whereas RE projects to CA1 of the dorsal and ventral hippocampus and to the subiculum. SUM and RE fibers to the hippocampus participate in common as well as in separate functions. Both systems would appear to amplify signals from other sources to their respective hippocampal targets. SUM amplifies signals from the entorhinal cortex (EC) to DG, whereas RE may amplify them from CA3 (and EC) to CA1 of the hippocampus. This “amplification” may serve to promote the transfer, encoding, and possibly storage of information from EC to DG and from CA3 and EC to CA1. Regarding their unique actions on the hippocampus, the SUM is a vital part of an ascending brainstem to hippocampal system generating the theta rhythm of the hippocampus, whereas RE importantly routes information from the medial prefrontal cortex to the hippocampus to thereby mediate functions involving both structures. In summary, although, to date, SUM and RE afferents to the hippocampus have not been extensively explored, the SUM and RE exert a profound influence on the hippocampus in processes of learning and memory. PMID:26072237

  20. Oxytocin in hypothalamic supraoptic nucleus is transferred to the caudate nucleus to influence pain modulation.

    PubMed

    Pan, Yang-Juan; Wang, Da-Xin; Yang, Jun; He, Xue-Ling; Xiao, Nai-Min; Ma, Rui-Qing; Wang, Chang-Hong; Lin, Bao-Cheng

    2016-08-01

    Oxytocin (OXT), which is synthesized and secreted in the hypothalamic supraoptic nucleus (SON), is the most important bioactive substance in SON regulating pain process. Our previous study has pointed that OXT in the caudate nucleus (CdN) plays a role in pain modulation. The communication was designed to investigate the source of OXT in the rat CdN during pain process using the methods of push-pull perfusion and radioimmunoassay. The results showed that (1) pain stimulation increased the OXT concentration in the CdN perfusion liquid; (2) SON cauterization inhibited the increase of OXT concentration in CdN perfusion liquid induced by the pain stimulation, which role in both sides of SON cauterization was stronger than that in one side of SON cauterization; and (3) SON microinjection of l-glutamate sodium, which excited the SON neurons, increased OXT concentration in the CdN perfusion liquid. The data suggested that OXT in the CdN was influenced by SON during pain process, i.e., OXT in the SON might be transferred to the CdN to influence pain modulation. PMID:27045802

  1. Interaction between hypothalamic dorsomedial nucleus and the suprachiasmatic nucleus determines intensity of food anticipatory behavior

    PubMed Central

    Acosta-Galvan, Guadalupe; Yi, Chun-Xia; van der Vliet, Jan; Jhamandas, Jack H.; Panula, Pertti; Angeles-Castellanos, Manuel; del Carmen Basualdo, María; Escobar, Carolina; Buijs, Ruud M.

    2011-01-01

    Food anticipatory behavior (FAA) is induced by limiting access to food for a few hours daily. Animals anticipate this scheduled meal event even without the suprachiasmatic nucleus (SCN), the biological clock. Consequently, a food-entrained oscillator has been proposed to be responsible for meal time estimation. Recent studies suggested the dorsomedial hypothalamus (DMH) as the site for this food-entrained oscillator, which has led to considerable controversy in the literature. Herein we demonstrate by means of c-Fos immunohistochemistry that the neuronal activity of the suprachiasmatic nucleus (SCN), which signals the rest phase in nocturnal animals, is reduced when animals anticipate the scheduled food and, simultaneously, neuronal activity within the DMH increases. Using retrograde tracing and confocal analysis, we show that inhibition of SCN neuronal activity is the consequence of activation of GABA-containing neurons in the DMH that project to the SCN. Next, we show that DMH lesions result in a loss or diminution of FAA, simultaneous with increased activity in the SCN. A subsequent lesion of the SCN restored FAA. We conclude that in intact animals, FAA may only occur when the DMH inhibits the activity of the SCN, thus permitting locomotor activity. As a result, FAA originates from a neuronal network comprising an interaction between the DMH and SCN. Moreover, this study shows that the DMH–SCN interaction may serve as an intrahypothalamic system to gate activity instead of rest overriding circadian predetermined temporal patterns. PMID:21402951

  2. Energy dependence of the nucleus-nucleus potential close to the Coulomb barrier

    SciTech Connect

    Washiyama, Kouhei; Lacroix, Denis

    2008-08-15

    The nucleus-nucleus interaction potentials in heavy-ion fusion reactions are extracted from the microscopic time-dependent Hartree-Fock theory for the mass symmetric reactions {sup 16}O + {sup 16}O, {sup 40}Ca + {sup 40}Ca, and {sup 48}Ca + {sup 48}Ca and the mass asymmetric reactions {sup 16}O + {sup 40,} {sup 48}Ca, {sup 40}Ca + {sup 48}Ca, {sup 16}O + {sup 208}Pb, and {sup 40}Ca + {sup 90}Zr. When the c.m. energy is much higher than the Coulomb barrier energy, potentials deduced with the microscopic theory identify with the frozen density approximation. As the c.m. energy decreases and approaches the Coulomb barrier, potentials become energy dependent. This dependence indicates dynamical reorganization of internal degrees of freedom and leads to a reduction of the 'apparent' barrier felt by the two nuclei during fusion of the order of 2-3% compared to the frozen density case. Several examples illustrate that the potential landscape changes rapidly when the c.m. energy is in the vicinity of the Coulomb barrier energy. The energy dependence is expected to have a significant role on fusion around the Coulomb barrier.

  3. Pion production at 180/sup 0/ in nucleus-nucleus collisions

    SciTech Connect

    Chessin, S.A.

    1983-05-01

    A survey experiment of pion production at 180/sup 0/ in nucleus-nucleus collisions is presented. Beams of 1.05 GeV/A and 2.1 GeV/A protons, alphas, and carbon were used, as well as proton beams of 0.80 GeV, 3.5 GeV, and 4.89 GeV, and argon beams of 1.05 GeV/A and 1.83 GeV/A. This is the first such experiment to use the heavier beams. Targets used ranged from carbon to lead. An in-depth review of the literature, both experimental and theoretical, is also presented. The systematics of the data are discussed, and comparisons are made both with prior experiments and with the predictions of the models reviewed. The cross sections appear consistent with a simple single nucleon-nucleon collision picture, without the need for collective or other exotic effects. Suggestions for future work are made.

  4. Deconvolving the Nucleus of Centaurus A Using Chandra PSF Library

    NASA Technical Reports Server (NTRS)

    Karovska, Margarita

    2000-01-01

    Centaurus A (NGC 5128) is a giant early-type galaxy containing the nearest (at 3.5 Mpc) radio-bright Active Galactic Nucleus (AGN). Cen A was observed with the High Resolution Camera (HRC) on the Chandra X-ray Observatory on several occasions since the launch in July 1999. The high-angular resolution (less than 0.5 arcsecond) Chandra/HRC images reveal X ray multi-scale structures in this object with unprecedented detail and clarity, including the bright nucleus believed to be associated with a supermassive black hole. We explored the spatial extent of the Cen A nucleus using deconvolution techniques on the full resolution Chandra images. Model point spread functions (PSFs) were derived from the standard Chandra raytrace PSF library as well as unresolved point sources observed with Chandra. The deconvolved images show that the Cen A nucleus is resolved and asymmetric. We discuss several possible causes of this extended emission and of the asymmetries.

  5. Active diffusion positions the nucleus in mouse oocytes.

    PubMed

    Almonacid, Maria; Ahmed, Wylie W; Bussonnier, Matthias; Mailly, Philippe; Betz, Timo; Voituriez, Raphaël; Gov, Nir S; Verlhac, Marie-Hélène

    2015-04-01

    In somatic cells, the position of the cell centroid is dictated by the centrosome. The centrosome is instrumental in nucleus positioning, the two structures being physically connected. Mouse oocytes have no centrosomes, yet harbour centrally located nuclei. We demonstrate how oocytes define their geometric centre in the absence of centrosomes. Using live imaging of oocytes, knockout for the formin 2 actin nucleator, with off-centred nuclei, together with optical trapping and modelling, we discover an unprecedented mode of nucleus positioning. We document how active diffusion of actin-coated vesicles, driven by myosin Vb, generates a pressure gradient and a propulsion force sufficient to move the oocyte nucleus. It promotes fluidization of the cytoplasm, contributing to nucleus directional movement towards the centre. Our results highlight the potential of active diffusion, a prominent source of intracellular transport, able to move large organelles such as nuclei, providing in vivo evidence of its biological function.

  6. Cytotoxicity of nucleus-targeting fluorescent gold nanoclusters

    NASA Astrophysics Data System (ADS)

    Zhao, Jing-Ya; Cui, Ran; Zhang, Zhi-Ling; Zhang, Mingxi; Xie, Zhi-Xiong; Pang, Dai-Wen

    2014-10-01

    Gold nanoclusters (AuNCs) with ultra small sizes and unique fluorescence properties have shown promising potential for imaging the nuclei of living cells. However, little is known regarding the potential cytotoxicity of AuNCs after they enter the cell nucleus. The aim of this study is to investigate whether and how nucleus-targeting AuNCs affect the normal functioning of cells. Highly stable, water-soluble and bright fluorescent Au25NCs (the core of each nanocluster is composed of 25 gold atoms) were synthesized. Specific targeting of Au25NCs to the cell nucleus was achieved by conjugating the TAT peptide to the Au25NCs. Cell viability, cell morphology, cell apoptosis/necrosis, reactive oxygen species (ROS) level and mitochondrial membrane potential examinations were performed on different cell lines exposed to the nucleus-targeting Au25NCs. We found that the nucleus-targeting Au25NCs caused cell apoptosis in a dose-dependent manner. A possible mechanism for the cytotoxicity of the nucleus-targeting Au25NCs was proposed as follows: the nucleus-targeting Au25NCs induce the production of ROS, resulting in the oxidative degradation of mitochondrial components, in turn leading to apoptosis via a mitochondrial damage pathway. This work facilitates a better understanding of the toxicity of AuNCs, especially nucleus-targeting AuNCs.Gold nanoclusters (AuNCs) with ultra small sizes and unique fluorescence properties have shown promising potential for imaging the nuclei of living cells. However, little is known regarding the potential cytotoxicity of AuNCs after they enter the cell nucleus. The aim of this study is to investigate whether and how nucleus-targeting AuNCs affect the normal functioning of cells. Highly stable, water-soluble and bright fluorescent Au25NCs (the core of each nanocluster is composed of 25 gold atoms) were synthesized. Specific targeting of Au25NCs to the cell nucleus was achieved by conjugating the TAT peptide to the Au25NCs. Cell viability, cell

  7. Low-energy antinucleon-nucleus interaction revisited

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    2015-08-01

    Annihilation cross sections of antiprotons and antineutrons on the proton between 50 and 400 MeV/c show Coulomb focusing below 200 MeV/c and almost no charge-dependence above 200 MeV/c. Similar comparisons for heavier targets are not possible for lack of overlap between nuclear targets studied with and beams. Interpolating between -nucleus annihilation cross sections with the help of an optical potential to compare with -nucleus annihilation cross sections reveal unexpected features of Coulomb interactions in the latter. Direct comparisons between -nucleus and -nucleus annihilations at very low energies could be possible if cross sections are measured on the same targets and at the same energies as the available cross sections for . Such measurements may be feasible in the foreseeable future.

  8. Cloud condensation nucleus-sulfate mass relationship and cloud albedo

    NASA Technical Reports Server (NTRS)

    Hegg, Dean A.

    1994-01-01

    Analysis of previously published, simultaneous measurements of cloud condensation nucleus number concentration and sulfate mass concentration suggest a nonlinear relationship between the two variables. This nonlinearity reduces the sensitivity of cloud albedo to changes in the sulfur cycle.

  9. Nucleus management in manual small incision cataract surgery by phacosection.

    PubMed

    Ravindra, M S

    2009-01-01

    Nucleus management is critical in manual small incision cataract surgery (MSICS), as the integrity of the tunnel, endothelium and posterior capsule needs to be respected. Several techniques of nucleus management are in vogue, depending upon the specific technique of MSICS. Nucleus can be removed in toto or bisected or trisected into smaller segments. The pressure in the eye can be maintained at the desired level with the use of an anterior chamber maintainer or kept at atmospheric levels. In MSICS, unlike phacoemulsification, there is no need to limit the size of the tunnel or restrain the size of capsulorrhexis. Large well-structured tunnels and larger capsulorrhexis provide better control on the surgical maneuvers. Safety and simplicity of MSICS has made it extremely popular. The purpose of this article is to describe nucleus management by phacosection in MSICS.

  10. The integrative role of the pedunculopontine nucleus in human gait.

    PubMed

    Lau, Brian; Welter, Marie-Laure; Belaid, Hayat; Fernandez Vidal, Sara; Bardinet, Eric; Grabli, David; Karachi, Carine

    2015-05-01

    The brainstem pedunculopontine nucleus has a likely, although unclear, role in gait control, and is a potential deep brain stimulation target for treating resistant gait disorders. These disorders are a major therapeutic challenge for the ageing population, especially in Parkinson's disease where gait and balance disorders can become resistant to both dopaminergic medication and subthalamic nucleus stimulation. Here, we present electrophysiological evidence that the pedunculopontine and subthalamic nuclei are involved in distinct aspects of gait using a locomotor imagery task in 14 patients with Parkinson's disease undergoing surgery for the implantation of pedunculopontine or subthalamic nuclei deep brain stimulation electrodes. We performed electrophysiological recordings in two phases, once during surgery, and again several days after surgery in a subset of patients. The majority of pedunculopontine nucleus neurons (57%) recorded intrasurgically exhibited changes in activity related to different task components, with 29% modulated during visual stimulation, 41% modulated during voluntary hand movement, and 49% modulated during imaginary gait. Pedunculopontine nucleus local field potentials recorded post-surgically were modulated in the beta and gamma bands during visual and motor events, and we observed alpha and beta band synchronization that was sustained for the duration of imaginary gait and spatially localized within the pedunculopontine nucleus. In contrast, significantly fewer subthalamic nucleus neurons (27%) recorded intrasurgically were modulated during the locomotor imagery, with most increasing or decreasing activity phasically during the hand movement that initiated or terminated imaginary gait. Our data support the hypothesis that the pedunculopontine nucleus influences gait control in manners extending beyond simply driving pattern generation. In contrast, the subthalamic nucleus seems to control movement execution that is not likely to be gait

  11. Odyssey: Comet Nucleus Orbiter; A Discovery 2000 Proposal

    NASA Astrophysics Data System (ADS)

    Weissman, P. R.; Nilsen, E. N.; Smythe, W. D.; Marriott, J.; Reinert, R.; Delamere, W. A.; Odyssey Science Team

    2000-10-01

    Odyssey will be NASA's first comet nucleus orbiter mission. The spacecraft will be launched in June 2006 on a Delta 2925 expendable vehicle and will use solar electric propulsion to rendezvous with periodic Comet Kopff in September 2009. Kopff is one of the most active short-period comets known, with a gas production near perihelion of 5 x 1028 molecules/sec and an estimated nucleus diameter of { ~}3.6 km. En route to Kopff, Odyssey will fly by the C-type asteroid 24 Themis, the largest asteroid ever encountered by a planetary spacecraft (d ≈ 215 km). Odyssey's scientific payload includes narrow and wide angle CCD cameras, an IR imaging radiometer, a gas chromatograph/mass spectrometer, a dust compositional analyzer, and a dust counter and accumulation sensors. The spacecraft will initially perform slow flybys of the active Kopff nucleus at distances between 500 and 100 km, and will then be placed in orbit around the nucleus at altitudes between 200 and 50 km. The in situ instruments will collect and analyze gas and dust in the cometary coma, providing elemental, molecular, isotopic, and mineralogic measurements of the cosmo-chemical record locked in comets of the origin of our solar system and the origin of life. The narrow angle camera will map the entire nucleus surface at a resolution of 1 m/pixel, providing detailed images of the nucleus topography and its change with time. The thermal imager will do the same at 21 m/pixel, providing unprecedented data on the energy balance at the surface of the cometary nucleus, key to understanding how the comet works. Odyssey will study Comet Kopff for 9 months. Extended mission options include: 1) higher resolution mapping at even lower altitudes, and 2) touch-down of the spacecraft on the nucleus surface.

  12. Under Pressure: Mechanical Stress Management in the Nucleus

    PubMed Central

    Belaadi, Néjma; Aureille, Julien; Guilluy, Christophe

    2016-01-01

    Cells are constantly adjusting to the mechanical properties of their surroundings, operating a complex mechanochemical feedback, which hinges on mechanotransduction mechanisms. Whereas adhesion structures have been shown to play a central role in mechanotransduction, it now emerges that the nucleus may act as a mechanosensitive structure. Here, we review recent advances demonstrating that mechanical stress emanating from the cytoskeleton can activate pathways in the nucleus which eventually impact both its structure and the transcriptional machinery. PMID:27314389

  13. Acts and knowledge management in the NUCLEUS hospital information system.

    PubMed Central

    Kanoui, H.; Joubert, M.; Favard, R.; Maury, G.; Pelletier, M.

    1995-01-01

    NUCLEUS is a project completed in June 1995 in the frame of the European Community programme AIM (Advanced Informatics in Medicine). The main result of NUCLEUS is a prototype of an integrated patient dossier. Together with this patient dossier, facilities have been developed for its customisation by the various categories of end-users. A semantic model has been designed to guide and control the exploitation of data, and ensures the overall integrity of the information system. PMID:8563297

  14. Truncal ataxia from infarction involving the inferior olivary nucleus.

    PubMed

    Park, Jae Hyun; Ryoo, Sookyung; Moon, So Young; Seo, Sand Won; Na, Duk L

    2012-08-01

    Truncal ataxia in medullary infarction may be caused by involvement of the lateral part of the medulla; however, truncal ataxia in infarction involving the inferior olivary nucleus (ION) has received comparatively little attention. We report a patient with truncal ataxia due to medial medullary infarction located in the ION. A lesion in the ION could produce a contralateral truncal ataxia due to increased inhibitory input to the contralesional vestibular nucleus from the contralesional flocculus.

  15. A FIBER APPARATUS IN THE NUCLEUS OF THE YEAST CELL

    PubMed Central

    Robinow, C. F.; Marak, J.

    1966-01-01

    The structure and mode of division of the nucleus of budding yeast cells have been studied by phase-contrast microscopy during life and by ordinary microscopy after Helly fixation. The components of the nucleus were differentially stained by the Feulgen procedure, with Giemsa solution after hydrolysis, and with iron alum haematoxylin. New information was obtained in cells fixed in Helly's by directly staining them with 0.005% acid fuchsin in 1% acetic acid in water. Electron micrographs have been made of sections of cells that were first fixed with 3% glutaraldehyde, then divested of their walls with snail juice, and postfixed with osmium tetroxide. Light and electron microscopy have given concordant information about the organization of the yeast nucleus. A peripheral segment of the nucleus is occupied by relatively dense matter (the "peripheral cluster" of Mundkur) which is Feulgen negative. The greater part of the nucleus is filled with fine-grained Feulgen-positive matter of low density in which chromosomes could not be identified. Chromosomes become visible in this region under the light microscope at meiosis. In the chromatin lies a short fiber with strong affinity for acid fuchsin. The nucleus divides by elongation and constriction, and during this process the fiber becomes long and thin. Electron microscopy has resolved it into a bundle of dark-edged 150 to 180 A filaments which extends between "centriolar plaques" that are attached to the nuclear envelope. PMID:5331666

  16. Suprachiasmatic Nucleus Neuropeptide Expression in Patients with Huntington's Disease

    PubMed Central

    van Wamelen, Daniel J.; Aziz, N. Ahmad; Anink, Jasper J.; van Steenhoven, Robin; Angeloni, Debora; Fraschini, Franco; Jockers, Ralf; Roos, Raymund A. C.; Swaab, Dick F.

    2013-01-01

    Study Objective: To study whether sleep and circadian rhythm disturbances in patients with Huntington's disease (HD) arise from dysfunction of the body's master clock, the hypothalamic suprachiasmatic nucleus. Design: Postmortem cohort study. Patients: Eight patients with HD and eight control subjects matched for sex, age, clock time and month of death, postmortem delay, and fixation time of paraffin-embedded hypothalamic tissue. Measurements and Results: Using postmortem paraffin-embedded tissue, we assessed the functional integrity of the suprachiasmatic nucleus in patients with HD and control subjects by determining the expression of two major regulatory neuropeptides, vasoactive intestinal polypeptide and arginine vasopressin. Additionally, we studied melatonin 1 and 2 receptor expression. Compared with control subjects, the suprachiasmatic nucleus contained 85% fewer neurons immunoreactive for vasoactive intestinal polypeptide and 33% fewer neurons for arginine vasopressin in patients with HD (P = 0.002 and P = 0.027). The total amount of vasoactive intestinal polypeptide and arginine vasopressin messenger RNA was unchanged. No change was observed in the number of melatonin 1 or 2 receptor immunoreactive neurons. Conclusions: These findings indicate posttranscriptional neuropeptide changes in the suprachiasmatic nucleus of patients with HD, and suggest that sleep and circadian rhythm disorders in these patients may at least partly arise from suprachiasmatic nucleus dysfunction. Citation: van Wamelen DJ; Aziz NA; Anink JJ; van Steenhoven R; Angeloni D; Fraschini F; Jockers R; Roos RAC; Swaab DF. Suprachiasmatic nucleus neuropeptide expression in patients with Huntington's disease. SLEEP 2013;36(1):117–125. PMID:23288978

  17. Masses of proton-rich T/sub z/<0 nuclei via the isobaric mass equation

    SciTech Connect

    Pape, A.; Antony, M.S.

    1988-07-01

    Masses of T/sub z/<0 nuclei through the element Sm, corresponding to Aless than or equal to117, have been calculated with the isobaric multiplet mass equation using parameterizations of its constant b and T/sub z/>0 reference masses of Wapstra, Audi, and Hoekstra. copyright 1988 Academic Press, Inc.

  18. Beta-delayed multi-particle emission in proton rich nuclei

    NASA Astrophysics Data System (ADS)

    Borge, M. J. G.; Axelsson, L.; Äystö, J.; Bergmann, U. C.; Boutami, R.; Deendoven, P.; Fraile, L. M.; Fynbo, H. O. U.; Honkanen, A.; Hornshøj, P.; Huikari, J.; Jokinen, A.; Jonson, B.; Markenroth, K.; Martel, I.; Mukha, I.; Nilsson, T.; Nyman, G.; Oinonen, M.; Prezado, Y.; Riisager, K.; Tengblad, O.; Rolander, K. Wilhelmsen

    2002-04-01

    In this contribution examples of the application of new technologies to disentangle the mechanism of beta-delayed multi-particle emission are given. In particular the mechanism of β-delayed two-proton emission from 31Ar is resolved and proved to be sequential, both for isospin allowed and isospin forbidden transitions. The analysis of the 9C decay has been focused in the study of the 12.2 MeV state in 9B. The decay of this state to pαα occurs sequentially, partial decay branches through the 8Be(0+,2+) and 5Li(3/2-,1/2-) intermediate states have been determined. A BGT value of 1.20(15) is deduced, compared with the BGT-value of the mirror transition, a asymmetry factor δ=3.7(12) is obtained, the largest ever observed. A preview of β3α data from 12N decay is discussed. .

  19. 3200 Phaethon, Asteroid or Comet Nucleus?

    NASA Astrophysics Data System (ADS)

    Boice, Daniel C.; Benkhoff, Johannes

    2015-08-01

    Physico-chemical modeling is central to understand the important physical processes in small solar system bodies. We have developed a computer simulation, SUISEI, that includes the physico-chemical processes relevant to comets within a global modeling framework. Our goals are to gain valuable insights into the intrinsic properties of cometary nuclei so we can better understand observations and in situ measurements. SUISEI includes a 3-D model of gas and heat transport in porous sub-surface layers in the interior of the nucleus.We present results on the application of SUISEI to the near-Sun object, Phaethon. Discovered in 1983 and classified as an asteroid, it has recently exhibited an active dust coma. Phaethon has long been associated as the source of the Geminids meteor shower so the dust activity provides a clear link to the meteor shower. The observed dust activity would traditionally lead to Phaethon being also classified as a comet (e.g., 2060-95P/Chiron, 133P/Elst-Pizarro). This is unusual since the orbit of Phaethon has a perihelion of 0.14 AU, resulting in surface temperatures of more than 1025K, much too hot for water ice or other volatiles to exist near the surface and drive the activity. This situation and others such as the “Active Asteroids” necessitates a revision of how we understand and classify these small asteroid-comet transition objects.We conclude the following for Phaethon:1. It is likely to contain relatively pristine volatiles in its interior despite repeated near perihelion passages of 0.14 AU during its history in its present orbit,2. Steady water gas fluxes at perihelion and throughout its orbit are insufficient to entrain the currently observed dust production,3. Thermal gradients into the surface as well as those caused by diurnal rotation are consistent with the mechanism of dust release due to thermal fracture,4. The initial large gas release during the first perihelion passage may be sufficient to produce enough dust to explain

  20. Stopping powers and cross sections due to two-photon processes in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Cheung, Wang K.; Norbury, John W.

    1994-01-01

    The effects of electromagnetic-production processes due to two-photon exchange in nucleus-nucleus collisions are discussed. Feynman diagrams for two-photon exchange are evaluated using quantum electrodynamics. The total cross section and stopping power for projectile and target nuclei of identical charge are found to be significant for heavy nuclei above a few GeV per nucleon-incident energy.

  1. Toward construction of a unified neutrino-nucleus interaction model

    NASA Astrophysics Data System (ADS)

    Kamano, Hiroyuki

    2014-09-01

    A precise knowledge of the neutrino-nucleus interactions is becoming one of the crucial issues for a successful determination of the neutrino parameters from the future neutrino-oscillation experiments. It is therefore urgent to have a reliable neutrino-nucleus interactoin model that enables a quantitative description of neutrino-nucleus reaction cross sections in an accuracy of 10 percent or less. However, the kinematic regions relevant to the neutrino parameter searches extend over the quasi-elastic, resonance, and deep-inelastic-scattering regions, where different theoretical treatments based on hadronic or partonic degrees of freedom are usually employed, and this makes the construction of a unified neutrino-nucleus interaction model covering those kinematic regions challenging. To tackle on such a challenging issue, we have recently developed a collaboration of experimentalists and theorists in different fields at J-PARC Branch of KEK Theory Center (http://www.nuint.kek.jp/index_e.html). In this talk, I review our efforts toward construction of the unified neutrino-nucleus interaction model at J-PARC Branch of KEK Theory Center. A precise knowledge of the neutrino-nucleus interactions is becoming one of the crucial issues for a successful determination of the neutrino parameters from the future neutrino-oscillation experiments. It is therefore urgent to have a reliable neutrino-nucleus interactoin model that enables a quantitative description of neutrino-nucleus reaction cross sections in an accuracy of 10 percent or less. However, the kinematic regions relevant to the neutrino parameter searches extend over the quasi-elastic, resonance, and deep-inelastic-scattering regions, where different theoretical treatments based on hadronic or partonic degrees of freedom are usually employed, and this makes the construction of a unified neutrino-nucleus interaction model covering those kinematic regions challenging. To tackle on such a challenging issue, we have

  2. Nucleus-nucleus cold fusion reactions analyzed with the l-dependent 'fusion by diffusion' model

    SciTech Connect

    Cap, T.; Siwek-Wilczynska, K.; Wilczynski, J.

    2011-05-15

    We present a modified version of the Fusion by Diffusion (FBD) model aimed at describing the synthesis of superheavy nuclei in cold fusion reactions, in which a low excited compound nucleus emits only one neutron. The modified FBD model accounts for the angular momentum dependence of three basic factors determining the evaporation residue cross section: the capture cross section {sigma}{sub cap}(l), the fusion probability P{sub fus}(l), and the survival probability P{sub surv}(l). The fusion hindrance factor, the inverse of P{sub fus}(l), is treated in terms of thermal fluctuations in the shape degrees of freedom and is expressed as a solution of the Smoluchowski diffusion equation. The l dependence of P{sub fus}(l) results from the l-dependent potential energy surface of the colliding system. A new parametrization of the distance of starting point of the diffusion process is introduced. An analysis of a complete set of 27 excitation functions for production of superheavy nuclei in cold fusion reactions, studied in experiments at GSI Darmstadt, RIKEN Tokyo, and LBNL Berkeley, is presented. The FBD model satisfactorily reproduces shapes and absolute cross sections of all the cold fusion excitation functions. It is shown that the peak position of the excitation function for a given 1n reaction is determined by the Q value of the reaction and the height of the fission barrier of the final nucleus. This fact could possibly be used in future experiments (with well-defined beam energy) for experimental determination of the fission barrier heights.

  3. PREFACE: 11th International Conference on Nucleus-Nucleus Collisions (NN2012)

    NASA Astrophysics Data System (ADS)

    Li, Bao-An; Natowitz, Joseph B.

    2013-03-01

    The 11th International Conference on Nucleus-Nucleus Collisions (NN2012) was held from 27 May to 1 June 2012, in San Antonio, Texas, USA. It was jointly organized and hosted by The Cyclotron Institute at Texas A&M University, College Station and The Department of Physics and Astronomy at Texas A&M University-Commerce. Among the approximately 300 participants were a large number of graduate students and post-doctoral fellows. The Keynote Talk of the conference, 'The State of Affairs of Present and Future Nucleus-Nucleus Collision Science', was given by Dr Robert Tribble, University Distinguished Professor and Director of the TAMU Cyclotron Institute. During the conference a very well-received public lecture on neutrino astronomy, 'The ICEcube project', was given by Dr Francis Halzen, Hilldale and Gregory Breit Distinguished Professor at the University of Wisconsin, Madison. The Scientific program continued in the general spirit and intention of this conference series. As is typical of this conference a broad range of topics including fundamental areas of nuclear dynamics, structure, and applications were addressed in 42 plenary session talks, 150 parallel session talks, and 21 posters. The high quality of the work presented emphasized the vitality and relevance of the subject matter of this conference. Following the tradition, the NN2012 International Advisory Committee selected the host and site of the next conference in this series. The 12th International Conference on Nucleus-Nucleus Collisions (NN2015) will be held 21-26 June 2015 in Catania, Italy. It will be hosted by The INFN, Laboratori Nazionali del Sud, INFN, Catania and the Dipartimento di Fisica e Astronomia of the University of Catania. The NN2012 Proceedings contains the conference program and 165 articles organized into the following 10 sections 1. Heavy and Superheavy Elements 2. QCD and Hadron Physics 3. Relativistic Heavy-Ion Collisions 4. Nuclear Structure 5. Nuclear Energy and Applications of

  4. Direct measurement of critical nucleus size in confined volumes.

    PubMed

    Liu, Jian; Nicholson, Catherine E; Cooper, Sharon J

    2007-06-19

    In crystallization, the critical nucleus size is of pivotal importance. Above this size, it is favorable for the new crystalline phase to form; below this size, the clusters will tend to dissolve rather than grow. To date, there has been no direct method for measuring the critical nucleus size. Instead, the size is typically calculated from the variation of crystallization rates with temperature. This involves using bulk values of the interfacial tension and enthalpy of fusion, which are inappropriate for small critical nucleus sizes. Here, we present a direct method for measuring the size of the critical nucleus, based on observing crystallization temperatures of materials within microemulsions. Using this approach, the number of molecules in the critical nucleus can be found simply by measuring the droplet size. Data on the freezing of water in water-in-oil microemulsions with and without the nucleating agent, heptacosanol, are presented to support our hypothesis. The results show that the critical nucleus contains 90-350 ice molecules for water pool radii of approximately 1.2-1.8 nm for the heptacosanol-doped microemulsions in which heterogeneous nucleation is initiated at the droplet interface. For the microemulsions without heptacosanol, the critical nucleus contains 70-210 ice molecules for water pool radii of approximately 1.2-1.8 nm. The smaller values arise because homogeneous nucleation occurs and therefore the crystallization temperatures are lower. We can also determine how bulk properties are perturbed at the nanoscale, and we find that the ratio of the ice-water interfacial tension to the enthalpy of fusion decreases significantly for water pool radii that are <2 nm.

  5. Regional connections of the mediodorsal thalamic nucleus in the rat.

    PubMed

    Bay, Hüsniye Hacıoğlu; Cavdar, Safiye

    2013-06-01

    Thalamic nuclei are classified as first- and higher-order relays. The first-order relays receive their driving afferents from ascending pathways and transmit messages to cortex that cortex has not seen before. The higher-order relays receive driver messages from layer-5 cortical cells for transmission from one cortical area to another. The present study used the retrograde tracer, fluoro-gold, to define the afferents to the three regions of the mediodorsal thalamic nucleus, to distinguish which parts contain first- or higher-order relays. The results show that the main inputs to the medial region of the nucleus come from olfactory and visceral structures, those to the central region come from limbic structures and those to the lateral region come from motor centers of the central nervous system. The medial and central regions receive both modulatory (layer 6) and driver (layer 5) afferent inputs from the orbitofrontal and medial frontal areas of the prefrontal cortex whereas the lateral region receives no layer-5 inputs from its cortical connections. Further, the inhibitory modulation of the mediodorsal thalamic nucleus shows regional differences. The medial region receives inhibitory afferents from the striatum (globus pallidus, caudate-putamen), the lateral region from the substantia nigra pars reticulata and the zona incerta, and all segments of the mediodorsal thalamic nucleus receive inhibitory afferents from the thalamic reticular nucleus. The results of the present study show that each region of the mediodorsal thalamic nucleus has distinct afferent connections allowing each region of mediodorsal thalamic nucleus to be considered relatively independent subnuclei that may subserve independent functions. PMID:23869861

  6. Calculated dynamical evolution of the nucleus of comet Hartley 2

    NASA Astrophysics Data System (ADS)

    Ksanfomality, Leonid

    2013-04-01

    The nucleus of comet Hartley 2 has a relatively regular dumbbell shape with unequal heads. The narrow part of elongated shape contains a relatively smooth region whose covering material is highly different in its shallow structure compared to other parts of this celestial body. The surface of crudely spherical parts of the nucleus is different from the surface of the "neck", which implies a hypothesis that the shape of the nucleus of Hartley 2 is indicative of destruction of this celestial body occurring in our days. The nucleus rotates around its axis passing through the center of mass, and centrifugal forces arise. This process is hindered by gravitation between parts of the nucleus and gradual slowing of rotation due to body lengthening because of the increase in the moment of inertia (proportional to R2) and due to friction losses in the neck material. We posed the task to determine centrifugal and gravitational forces in the neck (and, respectively, the strains of stretching and compression), the moment of inertia of the body and supply of its rotational energy E, the volume of the nucleus and its average density, and the position of the barycenter and center of rotation. It can be assumed that these forces cause slow but progressive lengthening of the neck which should eventually result in fragmentation of the nucleus. Centrifugal forces can be found as a result of summation of forces produced by parts of the body. According to the calculation model, the total stretching forces in the section passing through the narrowest cut of the neck are 1.21E6 N. The corresponding compression forces in the section passing through the narrow section are 1.04E6 N. The comparison of these values indicates a paradoxical result: stretching strains dominate in the neck, while compressions are dominant in the section passing through the common center of mass. The excess of stretching strains in the neck is 11%. The inference is as follows: the right part of the neck and the

  7. Nucleus rostrolateralis: an expansion of the epithalamus in some actinopterygii.

    PubMed

    Saidel, William M

    2013-10-01

    The diencephalic nucleus rostrolateralis (RL) in the African butterfly fish (Pantodon buchholzi) is a brain nucleus identified in fewer than a dozen of the ∼25,000 species of actinopterygian fishes. Located in the rostrolateral diencephalon, this nucleus in Pantodon receives direct and indirect visual input from the superior visual field. Its lack of precedent or consistent phylogenetic expression creates a difficulty in interpreting the functional role of this nucleus within the visual system. By tracing experiments, RL was found to be afferent to nucleus interpeduncularis (IP) and the target of cells from the subpallium of the telencephalon. RL is a component of a descending telencephalic pathway involved in at least one behavior at the intersection of limbic and somatic activities--feeding. The parallelism between the ventral telencephalon--RL--IP and the limbic/striatal--habenula--IP pathway (the dorsal diencephalic conduction system, DDCS) suggests that RL is a component within the DDCS. Moreover, the hodological connections of RL suggest that RL is likely a hypertrophy of the lateral habenula.

  8. Actin nucleators in the nucleus: an emerging theme.

    PubMed

    Weston, Louise; Coutts, Amanda S; La Thangue, Nicholas B

    2012-08-01

    Actin is an integral component of the cytoskeleton, forming a plethora of macromolecular structures that mediate various cellular functions. The formation of such structures relies on the ability of actin monomers to associate into polymers, and this process is regulated by actin nucleation factors. These factors use monomeric actin pools at specific cellular locations, thereby permitting rapid actin filament formation when required. It has now been established that actin is also present in the nucleus, where it is implicated in chromatin remodelling and the regulation of eukaryotic gene transcription. Notably, the presence of typical actin filaments in the nucleus has not been demonstrated directly. However, studies in recent years have provided evidence for the nuclear localisation of actin nucleation factors that promote cytoplasmic actin polymerisation. Their localisation to the nucleus suggests that these proteins mediate collaboration between the cytoskeleton and the nucleus, which might be dependent on their ability to promote actin polymerisation. The nature of this cooperation remains enigmatic and it will be important to elucidate the physiological relevance of the link between cytoskeletal actin networks and nuclear events. This Commentary explores the current evidence for the nuclear roles of actin nucleation factors. Furthermore, the implication of actin-associated proteins in relaying exogenous signals to the nucleus, particularly in response to cellular stress, will be considered.

  9. Coordinated Dynamics of RNA Splicing Speckles in the Nucleus.

    PubMed

    Zhang, Qiao; Kota, Krishna P; Alam, Samer G; Nickerson, Jeffrey A; Dickinson, Richard B; Lele, Tanmay P

    2016-06-01

    Despite being densely packed with chromatin, nuclear bodies and a nucleoskeletal network, the nucleus is a remarkably dynamic organelle. Chromatin loops form and relax, RNA transcripts and transcription factors move diffusively, and nuclear bodies move. We show here that RNA splicing speckled domains (splicing speckles) fluctuate in constrained nuclear volumes and remodel their shapes. Small speckles move in a directed way toward larger speckles with which they fuse. This directed movement is reduced upon decreasing cellular ATP levels or inhibiting RNA polymerase II activity. The random movement of speckles is reduced upon decreasing cellular ATP levels, moderately reduced after inhibition of SWI/SNF chromatin remodeling and modestly increased upon inhibiting RNA polymerase II activity. To define the paths through which speckles can translocate in the nucleus, we generated a pressure gradient to create flows in the nucleus. In response to the pressure gradient, speckles moved along curvilinear paths in the nucleus. Collectively, our results demonstrate a new type of ATP-dependent motion in the nucleus. We present a model where recycling splicing factors return as part of small sub-speckles from distal sites of RNA processing to larger splicing speckles by a directed ATP-driven mechanism through interchromatin spaces.

  10. Zolpidem modulates GABA(A) receptor function in subthalamic nucleus.

    PubMed

    Chen, Lei; Xie, Jun-Xia; Fung, Kam-Shuen; Yung, Wing-Ho

    2007-05-01

    The subthalamic nucleus occupies a position in the indirect pathway of basal ganglia circuit, which plays an important role in the movement regulation. Zolpidem is an imidazopyridine agonist with a high affinity on the benzodiazepine site of GABA(A) receptors containing alpha 1 subunit. Recently, zolpidem has been reported to be useful in treating subgroups of parkinsonian patients. A high density of zolpidem binding sites has been shown in rat subthalamic nucleus. To further investigate the modulation of zolpidem on GABA(A) receptor-mediated inhibitory synaptic current in subthalamic nucleus, whole-cell patch clamp recordings were used in the present study. Zolpidem at 100nM significantly prolonged the decay time and rise time of miniature inhibitory postsynaptic currents, with no effect on the amplitude and frequency. The benzodiazepine antagonist flumazenil could completely block the potentiation induced by zolpidem, confirming the specificity on the benzodiazepine site. At a high concentration of 1 microM, zolpidem significantly increased the decay time, rise time, amplitude and frequency of miniature inhibitory postsynaptic currents. In the behaving rats, unilateral microinjection of zolpidem into subthalamic nucleus induced a significant contralateral rotation. The present findings on the effect of zolpidem in subthalamic nucleus provide a rationale for further investigations into its potential in the treatment of Parkinson's disease. PMID:17337310

  11. The midbrain precommand nucleus of the mormyrid electromotor network.

    PubMed

    von der Emde, G; Sena, L G; Niso, R; Grant, K

    2000-07-15

    The functional role of the midbrain precommand nucleus (PCN) of the electromotor system was explored in the weakly electric mormyrid fish Gnathonemus petersii, using extracellular recording of field potentials, single unit activity, and microstimulation in vivo. Electromotor-related field potentials in PCN are linked in a one-to-one manner and with a fixed time relationship to the electric organ discharge (EOD) command cycle, but occur later than EOD command activity in the medulla. It is suggested that PCN electromotor-related field potentials arise from two sources: (1) antidromically, by backpropagation across electrotonic synapses between PCN axons and command nucleus neurons, and (2) as corollary discharge-driven feedback arriving from the command nucleus indirectly, via multisynaptic pathways. PCN neurons can be activated by electrosensory input, but this does not necessarily activate the whole motor command chain. Microstimulation of PCN modulates the endogenous pattern of electromotor command in a way that can mimic the structure of certain stereotyped behavioral patterns. PCN activity is regulated, and to a certain extent synchronized, by corollary discharge feedback inhibition. However, PCN does not generally function as a synchronized pacemaker driving the electromotor command chain. We propose that PCN neurons integrate information of various origins and individually relay this to the command nucleus in the medulla. Some may also have intrinsic, although normally nonsynchronized, pacemaker properties. This descending activity, integrated in the electromotor command nucleus, will play an important modulatory role in the central pattern generator decision process.

  12. Cochlear nucleus whole mount explants promote the differentiation of neuronal stem cells from the cochlear nucleus in co-culture experiments.

    PubMed

    Rak, Kristen; Völker, Johannes; Jürgens, Lukas; Völker, Christine; Frenz, Silke; Scherzad, Agmal; Schendzielorz, Philipp; Jablonka, Sibylle; Mlynski, Robert; Radeloff, Andreas; Hagen, Rudolf

    2015-08-01

    The cochlear nucleus is the first brainstem nucleus to receive sensory input from the cochlea. Depriving this nucleus of auditory input leads to cellular and molecular disorganization which may potentially be counteracted by the activation or application of stem cells. Neuronal stem cells (NSCs) have recently been identified in the neonatal cochlear nucleus and a persistent neurogenic niche was demonstrated in this brainstem nucleus until adulthood. The present work investigates whether the neurogenic environment of the cochlear nucleus can promote the survival of engrafted NSCs and whether cochlear nucleus-derived NSCs can differentiate into neurons and glia in brain tissue. Therefore, cochlear nucleus whole-mount explants were co-cultured with NSCs extracted from either the cochlear nucleus or the hippocampus and compared to a second environment using whole-mount explants from the hippocampus. Factors that are known to induce neuronal differentiation were also investigated in these NSC-explant experiments. NSCs derived from the cochlear nucleus engrafted in the brain tissue and differentiated into all cells of the neuronal lineage. Hippocampal NSCs also immigrated in cochlear nucleus explants and differentiated into neurons, astrocytes and oligodendrocytes. Laminin expression was up-regulated in the cochlear nucleus whole-mounts and regulated the in vitro differentiation of NSCs from the cochlear nucleus. These experiments confirm a neurogenic environment in the cochlear nucleus and the capacity of cochlear nucleus-derived NSCs to differentiate into neurons and glia. Consequently, the presented results provide a first step for the possible application of stem cells to repair the disorganization of the cochlear nucleus, which occurs after hearing loss. PMID:25960344

  13. Red blood cell extrudes nucleus and mitochondria against oxidative stress.

    PubMed

    Zhang, Zhong-Wei; Cheng, Jian; Xu, Fei; Chen, Yang-Er; Du, Jun-Bo; Yuan, Ming; Zhu, Feng; Xu, Xiao-Chao; Yuan, Shu

    2011-07-01

    Mammal red blood cells (erythrocytes) contain neither nucleus nor mitochondria. Traditional theory suggests that the presence of a nucleus would prevent big nucleated erythrocytes to squeeze through these small capillaries. However, nucleus is too small to hinder erythrocyte deformation. And, there is no sound reason to abandon mitochondria for the living cells. Here, we found that mammal erythrocyte reactive oxygen species (ROS) levels kept stable under diabetes, ischemia reperfusion, and malaria conditions or in vitro sugar/heme treatments, whereas bird erythrocyte ROS levels increased dramatically in these circumstances. Nuclear and mitochondrial extrusion may help mammal erythrocytes to better adapt to high-sugar and high-heme conditions by limiting ROS generation. PMID:21698761

  14. The Potential Roles of Actin in The Nucleus

    PubMed Central

    Falahzadeh, Khadijeh; Banaei-Esfahani, Amir; Shahhoseini, Maryam

    2015-01-01

    Over the past few decades, actin’s presence in the nucleus has been demonstrated. Actin is a key protein necessary for different nuclear processes. Although actin is well known for its functional role in dynamic behavior of the cytoskeleton, emerging studies are now highlighting new roles for actin. At the present time there is no doubt about the presence of actin in the nucleus. A number of studies have uncovered the functional involvement of actin in nuclear processes. Actin as one of the nuclear components has its own structured and functional rules, such as nuclear matrix association, chromatin remodeling, transcription by RNA polymerases I, II, III and mRNA processing. In this historical review, we attempt to provide an overview of our current understanding of the functions of actin in the nucleus. PMID:25870830

  15. Azimuthal harmonics of color fields in a high energy nucleus

    NASA Astrophysics Data System (ADS)

    Lappi, T.

    2015-05-01

    Recent experimental results have revealed a surprisingly rich structure of multiparticle azimuthal correlations in high energy proton-nucleus collisions. Final state collective effects can be responsible for many of the observed effects, but it has recently been argued that a part of these correlations are present already in the wavefunctions of the colliding particles. We evaluate the momentum space 2-particle cumulant azimuthal anisotropy coefficients vn { 2 }, n = 2 , 3 , 4 from fundamental representation Wilson line distributions describing the high energy nucleus. These would correspond to the flow coefficients in very forward proton-nucleus scattering. We find significant differences between Wilson lines from the MV model and from JIMWLK evolution. The magnitude and qualitative transverse momentum dependence of the vn { 2 } values suggest that the fluctuations present in the initial fields are a significant contribution to the observed anisotropies.

  16. Exotic nucleus helium 9 and its excited states

    SciTech Connect

    Seth, K.K.; Artuso, M.; Barlow, D.; Iversen, S.; Kaletka, M.; Nann, H.; Parker, B.; Soundranayagam, R.

    1987-05-11

    The ground state and several excited states of /sup 9/He, the most neutron-rich nucleus to date, have been identified by means of the reaction /sup 9/Be(..pi../sup -/,..pi../sup +/) /sup 9/He. The mass excess of the ground state has been measured and it is found that the nucleus is unbound against single-neutron decay by 1.13 +- 0.10 MeV only. It is found that the excited-state spectrum of this nucleus, which is very far from the valley of stability, is in good agreement with the predictions of ''no-core'' shell-model calculations whose parameters were optimized for the stable nuclei in the valley.

  17. Brain networks modulated by subthalamic nucleus deep brain stimulation.

    PubMed

    Accolla, Ettore A; Herrojo Ruiz, Maria; Horn, Andreas; Schneider, Gerd-Helge; Schmitz-Hübsch, Tanja; Draganski, Bogdan; Kühn, Andrea A

    2016-09-01

    Deep brain stimulation of the subthalamic nucleus is an established treatment for the motor symptoms of Parkinson's disease. Given the frequent occurrence of stimulation-induced affective and cognitive adverse effects, a better understanding about the role of the subthalamic nucleus in non-motor functions is needed. The main goal of this study is to characterize anatomical circuits modulated by subthalamic deep brain stimulation, and infer about the inner organization of the nucleus in terms of motor and non-motor areas. Given its small size and anatomical intersubject variability, functional organization of the subthalamic nucleus is difficult to investigate in vivo with current methods. Here, we used local field potential recordings obtained from 10 patients with Parkinson's disease to identify a subthalamic area with an analogous electrophysiological signature, namely a predominant beta oscillatory activity. The spatial accuracy was improved by identifying a single contact per macroelectrode for its vicinity to the electrophysiological source of the beta oscillation. We then conducted whole brain probabilistic tractography seeding from the previously identified contacts, and further described connectivity modifications along the macroelectrode's main axis. The designated subthalamic 'beta' area projected predominantly to motor and premotor cortical regions additional to connections to limbic and associative areas. More ventral subthalamic areas showed predominant connectivity to medial temporal regions including amygdala and hippocampus. We interpret our findings as evidence for the convergence of different functional circuits within subthalamic nucleus' portions deemed to be appropriate as deep brain stimulation target to treat motor symptoms in Parkinson's disease. Potential clinical implications of our study are illustrated by an index case where deep brain stimulation of estimated predominant non-motor subthalamic nucleus induced hypomanic behaviour.

  18. Figure Caption for pair of images of 'Comet Nucleus Q

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Figure Caption for pair of images of 'Comet Nucleus Q'. 21Jul94 Last Look at the Q-nuclei First image - March 30, 1994. Two Q-nuclei and a split nucleus, P. Second image - July 20, 1994. at T - 10 hours. Both nuclei still show no sign of further fragmentation, although the coma near each is being stretched out along the direction of motion. Both images were taken with the WFPC2 Planetary Camera using a red filter. Credit: H. A. Weaver and T. E. Smith

  19. Low-energy rotational bands in the nucleus155Eu

    NASA Astrophysics Data System (ADS)

    Katajanheimo, R.; Liljavirta, H.; Siivola, A.; Hammarén, E.; Liukkonen, E.

    1984-02-01

    Excited states in the nucleus155Eu have been produced during in-beam bombardments of a154Sm target with3He beams at 22 and 27 MeV. Decay gamma rays were detected using coincidence equipment optimized for low-energy photons. The level scheme is based on the observed γγ-coincidence relationships combined with the information on relative intensities. Tentatively suggested spin assignments follow from the apparent rotational character of the nucleus. Experimental observations are compared with predictions calculated from a particle-rotor model with a nonspheroidal Woods-Saxon potential.

  20. Neutral current neutrino-nucleus interactions at high energies

    SciTech Connect

    Gay Ducati, M. B.; Machado, M. M.; Machado, M. V. T.

    2009-04-01

    We present a QCD analysis of the neutral current (NC) neutrino-nucleus interaction at the small-x region using the color dipole formalism. This phenomenological approach is quite successful in describing experimental results in deep inelastic ep scattering and charged current neutrino-nucleus interactions at high energies. We present theoretical predictions for the relevant structure functions and the corresponding implications for the total NC neutrino cross section. It is shown that at small x, the NC boson-nucleon cross section should exhibit the geometric scaling property that has important consequences for ultrahigh energy neutrino phenomenology.

  1. Recent Developments in Neutrino/Antineutrino-Nucleus Interactions

    DOE PAGESBeta

    Morfín, Jorge G.; Nieves, Juan; Sobczyk, Jan T.

    2012-01-01

    Recent experimental results and developments in the theoretical treatment of neutrino-nucleus interactions in the energy range of 1–10 GeV are discussed. Difficulties in extracting neutrino-nucleon cross sections from neutrino-nucleus scattering data are explained and significance of understanding nuclear effects for neutrino oscillation experiments is stressed. Detailed discussions of the status of two-body current contribution in the kinematic region dominated by quasielastic scattering and specific features of partonic nuclear effects in weak DIS scattering are presented.

  2. Final State Interactions Effects in Neutrino-Nucleus Interactions

    SciTech Connect

    Golan, Tomasz; Juszczak, Cezary; Sobczyk, Jan T.

    2012-07-01

    Final State Interactions effects are discussed in the context of Monte Carlo simulations of neutrino-nucleus interactions. A role of Formation Time is explained and several models describing this effect are compared. Various observables which are sensitive to FSI effects are reviewed including pion-nucleus interaction and hadron yields in backward hemisphere. NuWro Monte Carlo neutrino event generator is described and its ability to understand neutral current $\\pi^0$ production data in $\\sim 1$ GeV neutrino flux experiments is demonstrated.

  3. Recent Developments in Neutrino/Antineutrino-Nucleus Interactions

    SciTech Connect

    Morfín, Jorge G.; Nieves, Juan; Sobczyk, Jan T.

    2012-01-01

    Recent experimental results and developments in the theoretical treatment of neutrino-nucleus interactions in the energy range of 1–10 GeV are discussed. Difficulties in extracting neutrino-nucleon cross sections from neutrino-nucleus scattering data are explained and significance of understanding nuclear effects for neutrino oscillation experiments is stressed. Detailed discussions of the status of two-body current contribution in the kinematic region dominated by quasielastic scattering and specific features of partonic nuclear effects in weak DIS scattering are presented.

  4. Analysis of organic compounds in returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.

    1989-01-01

    Techniques for analysis of organic compounds in returned comet nucleus samples are described. Interstellar, chondritic and transitional organic components are discussed. Appropriate sampling procedures will be essential to the success of these analyses. It will be necessary to return samples that represent all the various regimes found in the nucleus, e.g., a complete core, volatile components (deep interior), and crustal components (surface minerals, rocks, processed organics such as macromolecular carbon and polymers). Furthermore, sampling, storage, return, and distribution of samples must be done under conditions that preclude contamination of the samples by terrestrial matter.

  5. Altered mechanical properties of the nucleus in disease.

    PubMed

    Lombardi, Maria Lucia; Lammerding, Jan

    2010-01-01

    In eukaryotic cells, the nucleus is the largest and most rigid organelle. Therefore, its physical properties contribute critically to the biomechanical behavior of cells, e.g., during amoeboid migration or perfusion through narrow capillaries. Furthermore, it has been speculated that nuclear deformations could directly allow cells to sense mechanical stress, e.g., by modulating the access of specific transcription factors to their binding sites. Defects in nuclear mechanics have also been reported in a variety of muscular dystrophies caused by mutations in nuclear envelope proteins, indicating an important role in the maintenance of cells in mechanically stressed tissue. These findings have prompted the growing field of nuclear mechanics to develop advanced experimental methods to study the physical properties of the nucleus as a function of nuclear structure and organization, and to understand its role in physiology and disease. These experimental techniques include micropipette aspiration, atomic force microscopy of isolated nuclei, cellular strain and compression experiments, and microneedle manipulation of intact cells. These experiments have provided important insights into the mechanical behavior of the nucleus under physiological conditions, the distinct mechanical contributions of the nuclear lamina and interior, and how mutations in nuclear envelope proteins associated with a variety of human diseases can cause distinct alterations in the physical properties of the nucleus and contribute to the disease mechanism. Here, we provide a brief overview of the most common experimental techniques and their application and discuss the implication of their results on our current understanding of nuclear mechanics.

  6. CTP synthase forms cytoophidia in the cytoplasm and nucleus

    SciTech Connect

    Gou, Ke-Mian; Chang, Chia-Chun; Shen, Qing-Ji; Sung, Li-Ying; Liu, Ji-Long

    2014-04-15

    CTP synthase is an essential metabolic enzyme responsible for the de novo synthesis of CTP. Multiple studies have recently showed that CTP synthase protein molecules form filamentous structures termed cytoophidia or CTP synthase filaments in the cytoplasm of eukaryotic cells, as well as in bacteria. Here we report that CTP synthase can form cytoophidia not only in the cytoplasm, but also in the nucleus of eukaryotic cells. Both glutamine deprivation and glutamine analog treatment promote formation of cytoplasmic cytoophidia (C-cytoophidia) and nuclear cytoophidia (N-cytoophidia). N-cytoophidia are generally shorter and thinner than their cytoplasmic counterparts. In mammalian cells, both CTP synthase 1 and CTP synthase 2 can form cytoophidia. Using live imaging, we have observed that both C-cytoophidia and N-cytoophidia undergo multiple rounds of fusion upon glutamine analog treatment. Our study reveals the coexistence of cytoophidia in the cytoplasm and nucleus, therefore providing a good opportunity to investigate the intracellular compartmentation of CTP synthase. - Highlights: • CTP synthase forms cytoophidia not only in the cytoplasm but also in the nucleus. • Glutamine deprivation and Glutamine analogs promotes cytoophidium formation. • N-cytoophidia exhibit distinct morphology when compared to C-cytoophidia. • Both CTP synthase 1 and CTP synthase 2 form cytoophidia in mammalian cells. • Fusions of cytoophidia occur in the cytoplasm and nucleus.

  7. Measuring neutrino-nucleus interactions with MINERνA

    SciTech Connect

    Rodrigues, P. A.

    2015-07-15

    We present results from the MINERνA experiment for neutrino-nucleus scattering in the few-GeV energy region. These measurements cover a range of processes that must be modeled correctly in neutrino oscillation experiments, and in which recent results from other experiments have suggested deficiencies in the models currently used.

  8. High-energy pion-nucleus scattering at LAMPF

    SciTech Connect

    Morris, C.L.

    1993-01-01

    Recent data obtained for pion-nucleus interactions above the [triangle](1232) is presented. The expected long mean-free path at pion energies above the [3,3] resonance is demonstrated in elastic scattering. Evidence for unexpected nuclear transparency for outgoing pions at resonance energies is presented. A new technique measuring virtual [triangle] components of the nuclear wave function is suggested.

  9. High-energy pion-nucleus scattering at LAMPF

    SciTech Connect

    Morris, C.L.

    1993-02-01

    Recent data obtained for pion-nucleus interactions above the {triangle}(1232) is presented. The expected long mean-free path at pion energies above the [3,3] resonance is demonstrated in elastic scattering. Evidence for unexpected nuclear transparency for outgoing pions at resonance energies is presented. A new technique measuring virtual {triangle} components of the nuclear wave function is suggested.

  10. mRNA-Producing Pseudo-nucleus System.

    PubMed

    Shin, Seung Won; Park, Kyung Soo; Shin, Woo Jung; Um, Soong Ho

    2015-11-01

    A pseudo-eukaryotic nucleus (PEN) system consisting of a gene-containing DNA hydrogel encapsulated in a liposome is fabricated. Owing to the structural characteristics of gene-containing DNA hydrogel, mRNA transcription efficiency is promoted 2.57-fold. Through the use of PEN as a platform for mRNA delivery to the cytosol, prolonged protein translation is achieved.

  11. Synthesis of the Furan Nucleus Promoted by Ytterbium Triflate.

    PubMed

    Taddeo, Vito Alessandro; Genovese, Salvatore; Epifano, Francesco; Fiorito, Serena

    2015-11-01

    An efficient synthesis of differently substituted furans from acetylene dicarboxylates and β-dicarbonyl compounds is described. The furan nucleus was built by means of an Yb(OTf)3 catalyzed cycloaddition reaction yielding desired adducts in 91%-98% yield.

  12. Synthesis of the Furan Nucleus Promoted by Ytterbium Triflate.

    PubMed

    Taddeo, Vito Alessandro; Genovese, Salvatore; Epifano, Francesco; Fiorito, Serena

    2015-11-01

    An efficient synthesis of differently substituted furans from acetylene dicarboxylates and β-dicarbonyl compounds is described. The furan nucleus was built by means of an Yb(OTf)3 catalyzed cycloaddition reaction yielding desired adducts in 91%-98% yield. PMID:26749804

  13. Brackett Gamma Imaging of the Nucleus of M83

    NASA Astrophysics Data System (ADS)

    Crosthwaite, L. P.; Turner, J. L.; Beck, S. C.; Meier, D. S.

    2004-12-01

    The gas-rich nucleus of barred spiral galaxy, M83, is a hotbed of star formation, with a total infrared luminosity of 4 X 109 Lo. We have observed the nucleus of M83 with the near infrared spectrometer, NIRSPEC, on Keck 2 to obtain high resolution Brγ recombination line spectra of the nucleus. Simultaneous imaging with the SCAM camera in a broadband K filter shows the position of the slit on the near-infrared galaxy. This allows us to map the nucleus with a continuum reference. The SCAM image shows a bright peak at the nucleus and a complex semi-circular arc of emission to the southwest. We stepped the 0.5'' X 24'' length slit in small declination increments to map a 20'' X 20'' region just west of the nucleus. Individual spectra were used to form a ra-dec-lambda cube and an integrated intensity map of Brγ . A total of 1.1 X 10-16 W m-2 of Brγ emission is detected in the map, in good agreement with previous low resolution observations (Turner, Ho, & Beck 1987, ApJ, 313, 644). This is not corrected for extinction within the molecular clouds in M83 or to the nebulae themselves and is therefore a lower limit to the true Brγ flux. Extinction is estimated to be at least a magnitude in the near-IR as measured in larger (4'') beams (Turner et al.) The bulk of the Brγ emission extends along the northern portion of the near-IR continuum semi-circle. Twenty percent of the total Brγ emission comes from single a 3'' (FWHM) source located 5'' west of the near-IR nucleus. The complementary NIRSPEC Brα data we have obtained will eventually allow us to evaluate the near-IR extinction on subarcsecond sizescales and obtain an extinction-corrected estimate of the Lyman continuum rate and therefore the number of ionizing stars.

  14. Physical interrelation of volatile and refractories in a cometary nucleus

    NASA Astrophysics Data System (ADS)

    Fulle, Marco; Alice Team (PI Alan Stern), CONSTERT Team (PI Wlodek Kofman), COSIMA Team (PI Martin Hilchenbach), GIADA Team (PI Alessandra Rotundi), MIDAS Team (PI Mark Bentley), MIRO Team (PI Mark Hofstadter), OSIRIS Team (PI Holger Sierks), ROSINA Team (PI Kathrin Altwegg), RPC Team (PIs Hans Nilsson, James Burch, Anders Eriksson, Karl Heinz-Glassmeier, Pierre Henri, Christopher Carr), RSI Team (PI Martin Paetzold), VIRTIS Team (PI Fabrizio Capaccioni), Lander Team (Lead Scientists: Hermann Boehnhardt and Jean-Pierre Bibring), IDS Team (Eberhard Gruen, Marcello Fulchignoni, Paul Weissman), Project Scientist Team (Matt Taylor, Bonnie Buratti, Nicolas Altobelli, Mathieu Choukroun), Ground-Based Observations Team (Colin Snodgrass)

    2016-10-01

    The Rosetta mission has been taking measurements of its target comet Comet 67P/Churyumov-Gerasimenko since early 2014 and will complete operations at the end of September 2016. The mission Science Management Plan, in 1994, laid out the the prime goals and themes of the mission. These five themes were: 1) To study the global characterisation of the Nuclues, the determination of the dynamics properties , surface morpholy and composition of the comet. 2) Examination of the Chemical, Mineralogical and isotopic compositions of volatiles and refractories in a cometary nucleus.3) Physical interrelation of volatile and refractories in a cometary nucleus4) Study the development of cometary activity and the process in the surface layer of the nucleus and in the inner coma5) The origins of comets, the relationship between cometary and interstellar material and the implications for the origin of the solar system,To cover all aspects of the Rosetta mission in this special Show case session, this abstracts is one of 5, with this particular presentation focusing on theme 3, in particular on a) The dust-to-gas ratio; b) distributed sources of volatiles; c) seasonal evolution of the dust size distribution.a) The dust-to-gas ratio has been provided by coma observations measuring the gas and dust loss rates from the nucleus surface. The ratio of these two loss rates provides a lower limit of the dust-to-gas ratio at the nucleus surface, since it does not take into account the largest chunks unable to leave the nucleus, or falling back due to the dominant gravity. We review the value inferred so far, its time evolution, and new techniques to directly measure it in the nucleus.b) Evidences offered by Rosetta observations of gas sublimating from dust particles are up to now faint. We report the few available observations and an estimate of the probable average water content in dust particles inferred by 3D gas-dynamical codes of 67P coma.c) The dust-size distribution tunes the sizes

  15. Cytoskeletal tension induces the polarized architecture of the nucleus.

    PubMed

    Kim, Dong-Hwee; Wirtz, Denis

    2015-04-01

    The nuclear lamina is a thin filamentous meshwork that provides mechanical support to the nucleus and regulates essential cellular processes such as DNA replication, chromatin organization, cell division, and differentiation. Isolated horizontal imaging using fluorescence and electron microscopy has long suggested that the nuclear lamina is composed of structurally different A-type and B-type lamin proteins and nuclear lamin-associated membrane proteins that together form a thin layer that is spatially isotropic with no apparent difference in molecular content or density between the top and bottom of the nucleus. Chromosomes are condensed differently along the radial direction from the periphery of the nucleus to the nuclear center; therefore, chromatin accessibility for gene expression is different along the nuclear radius. However, 3D confocal reconstruction reveals instead that major lamin protein lamin A/C forms an apically polarized Frisbee-like dome structure in the nucleus of adherent cells. Here we show that both A-type lamins and transcriptionally active chromatins are vertically polarized by the tension exercised by the perinuclear actin cap (or actin cap) that is composed of highly contractile actomyosin fibers organized at the apical surface of the nucleus. Mechanical coupling between actin cap and lamina through LINC (linkers of nucleoskeleton and cytoskeleton) protein complexes induces an apical distribution of transcription-active subnucleolar compartments and epigenetic markers of transcription-active genes. This study reveals that intranuclear structures, such as nuclear lamina and chromosomal architecture, are apically polarized through the extranuclear perinuclear actin cap in a wide range of somatic adherent cells.

  16. GAS ACCRETION IN THE M32 NUCLEUS: PAST AND PRESENT

    SciTech Connect

    Seth, Anil C.

    2010-12-10

    Using adaptive optics assisted Gemini/NIFS data, I study the present and past gas accretion in the central 3'' of the M32 nucleus. From changes in the spectral slope and CO line depths near the center, I find evidence for unresolved dust emission resulting from black hole (BH) accretion. With a luminosity of {approx}2 x 10{sup 38} erg s{sup -1}, this dust emission appears to be the most luminous tracer of current BH accretion, 2 orders of magnitude more luminous than previously detected X-ray emission. These observations suggest that using high-resolution infrared data to search for dust emission may be an effective way to detect other nearby, low-luminosity BHs, such as those in globular clusters. I also examine the fossil evidence of gas accretion contained in the kinematics of the stars in the nucleus. The higher order moments (h3 and h4) of the line-of-sight velocity distribution show patterns that are remarkably similar to those seen on larger scales in elliptical galaxies and in gas-rich merger simulations. The kinematics suggests the presence of two components in the M32 nucleus, a dominant disk overlying a pressure supported component. I discuss possible formation scenarios for the M32 nucleus in the context of the kinematic data as well as previous stellar population studies. The kinematic measurements presented here are the highest quality available for the nucleus of M32, and may be useful for any future dynamical models of this benchmark system.

  17. Opposite regulation of body temperature by cholinergic input to the paraventricular nucleus and supraoptic nucleus in rats.

    PubMed

    Takahashi, A; Ishimaru, H; Ikarashi, Y; Kishi, E; Maruyama, Y

    2001-08-01

    Hypothalamic cholinergic system plays an important role in the regulation of body temperature and fluid balance. We have previously shown that cholinergic stimulation of the anterior hypothalamus and preoptic area was accompanied by a fall in body temperature, increased water intake, and increased Fos protein in the paraventricular nucleus (PVN) and supraoptic nucleus (SON). In the present study, to estimate the role played by cholinergic input to the PVN and SON in thermoregulation and water intake, we used microdialysis for cholinergic stimulation with neostigmine and analysis of the nucleus, and also investigated immunoreactivity for c-Fos protein in the brain. This stimulation increased extracellular concentration of acetylcholine in these nuclei. Stimulation of the PVN decreased body temperature and increased water intake. On the other hand, stimulation of the SON increased body temperature. Both in PVN-stimulated and SON-stimulated rats, c-Fos-like immunoreactivity (Fos-IR) was evident in the PVN, SON and certain regions including locus coeruleus (LC), area postrema and nucleus of the solitary tract (NTS). Addition of atropine to the dialysis medium attenuated the increase of Fos-IR and suppressed the cholinergic stimulation-induced responses in body temperature and water intake. These results suggest that cholinergic muscarinic mechanisms in PVN and SON play an opposite function in the regulation of body temperature. The same neuronal pathway including LC and NTS may participate in an advance both in hypothermia and in hyperthermia.

  18. Responses of primate caudal parabrachial nucleus and Kolliker-fuse nucleus neurons to whole body rotation

    NASA Technical Reports Server (NTRS)

    Balaban, Carey D.; McGee, David M.; Zhou, Jianxun; Scudder, Charles A.

    2002-01-01

    The caudal aspect of the parabrachial (PBN) and Kolliker-Fuse (KF) nuclei receive vestibular nuclear and visceral afferent information and are connected reciprocally with the spinal cord, hypothalamus, amygdala, and limbic cortex. Hence, they may be important sites of vestibulo-visceral integration, particularly for the development of affective responses to gravitoinertial challenges. Extracellular recordings were made from caudal PBN cells in three alert, adult female Macaca nemestrina through an implanted chamber. Sinusoidal and position trapezoid angular whole body rotation was delivered in yaw, roll, pitch, and vertical semicircular canal planes. Sites were confirmed histologically. Units that responded during rotation were located in lateral and medial PBN and KF caudal to the trochlear nerve at sites that were confirmed anatomically to receive superior vestibular nucleus afferents. Responses to whole-body angular rotation were modeled as a sum of three signals: angular velocity, a leaky integration of angular velocity, and vertical position. All neurons displayed angular velocity and integrated angular velocity sensitivity, but only 60% of the neurons were position-sensitive. These responses to vertical rotation could display symmetric, asymmetric, or fully rectified cosinusoidal spatial tuning about a best orientation in different cells. The spatial properties of velocity and integrated velocity and position responses were independent for all position-sensitive neurons; the angular velocity and integrated angular velocity signals showed independent spatial tuning in the position-insensitive neurons. Individual units showed one of three different orientations of their excitatory axis of velocity rotation sensitivity: vertical-plane-only responses, positive elevation responses (vertical plane plus ipsilateral yaw), and negative elevation axis responses (vertical plane plus negative yaw). The interactions between the velocity and integrated velocity components

  19. Semiphenomenological method of analysis for intermediate-energy alpha-nucleus elastic scattering data

    SciTech Connect

    Ahmad, I.; Alvi, M.A.

    1983-12-01

    We propose a semiphenomenological method of analysis for intermediate energy ..cap alpha..-nucleus elastic scattering experiments and demonstrate its usefulness by analyzing available elastic ..cap alpha..-nucleus scattering data at 1.37 GeV.

  20. Projections from the hypothalamic paraventricular nucleus and the nucleus of the solitary tract to prechoroidal neurons in the superior salivatory nucleus: Pathways controlling rodent choroidal blood flow.

    PubMed

    Li, Chunyan; Fitzgerald, Malinda E C; Ledoux, Mark S; Gong, Suzhen; Ryan, Patrick; Del Mar, Nobel; Reiner, Anton

    2010-10-28

    Using intrachoroidal injection of the transneuronal retrograde tracer pseudorabies virus (PRV) in rats, we previously localized preganglionic neurons in the superior salivatory nucleus (SSN) that regulate choroidal blood flow (ChBF) via projections to the pterygopalatine ganglion (PPG). In the present study, we used higher-order transneuronal retrograde labeling following intrachoroidal PRV injection to identify central neuronal cell groups involved in parasympathetic regulation of ChBF via input to the SSN. These prominently included the hypothalamic paraventricular nucleus (PVN) and the nucleus of the solitary tract (NTS), both of which are responsive to systemic BP and are involved in systemic sympathetic vasoconstriction. Conventional pathway tracing methods were then used to determine if the PVN and/or NTS project directly to the choroidal subdivision of the SSN. Following retrograde tracer injection into SSN (biotinylated dextran amine 3K or Fluorogold), labeled perikarya were found in PVN and NTS. Injection of the anterograde tracer, biotinylated dextran amine 10K (BDA10K), into PVN or NTS resulted in densely packed BDA10K+terminals in prechoroidal SSN (as defined by its enrichment in nitric oxide synthase-containing perikarya). Double-label studies showed these inputs ended directly on prechoroidal nitric oxide synthase-containing neurons of SSN. Our study thus establishes that PVN and NTS project directly to the part of SSN involved in parasympathetic vasodilatory control of the choroid via the PPG. These results suggest that control of ChBF may be linked to systemic blood pressure and central control of the systemic vasculature.

  1. Projections from the Hypothalamic Paraventricular Nucleus and the Nucleus of the Solitary Tract to Prechoroidal Neurons in the Superior Salivatory Nucleus: Pathways Controlling Rodent Choroidal Blood Flow

    PubMed Central

    Li, Chunyan; Fitzgerald, Malinda E.C.; LeDoux, Mark S.; Gong, Suzhen; Ryan, Patrick; Del Mar, Nobel; Reiner, Anton

    2010-01-01

    Using intrachoroidal injection of the transneuronal retrograde tracer pseudorabies virus (PRV) in rats, we previously localized preganglionic neurons in the superior salivatory nucleus (SSN) that regulate choroidal blood flow (ChBF) via projections to the pterygopalatine ganglion (PPG). In the present study, we used higher order transneuronal retrograde labeling following intrachoroidal PRV injection to identify central neuronal cell groups involved in parasympathetic regulation of ChBF via input to the SSN. These prominently included the hypothalamic paraventricular nucleus (PVN) and the nucleus of the solitary tract (NTS), both of which are responsive to systemic BP, and are involved in systemic sympathetic vasoconstriction. Conventional pathway tracing methods were then used to determine if the PVN and/or NTS project directly to the choroidal subdivision of the SSN. Following retrograde tracer injection into SSN (biotinylated dextran amine 3K or Fluorogold), labeled perikarya were found in PVN and NTS. Injection of the anterograde tracer, biotinylated dextran amine 10K (BDA10K) into PVN or NTS resulted in densely packed BDA10K+ terminals in prechoroidal SSN (as defined by its enrichment in nitric oxide synthase-containing perikarya). Double-label studies showed these inputs ended directly on prechoroidal nitric oxide synthase-containing neurons of SSN. Our study thus establishes that PVN and NTS project directly to the part of SSN involved in parasympathetic vasodilatory control of the choroid via the PPG. These results suggest that control of ChBF may be linked to systemic blood pressure and central control of the systemic vasculature. PMID:20801105

  2. Development of injectable hydrogels for nucleus pulposus replacement

    NASA Astrophysics Data System (ADS)

    Thomas, Jonathan D.

    Intervertebral disc degeneration has been reported as the underlying cause for 75% of cases of lower back pain and is marked by dehydration of the nucleus pulposus within the intervertebral disc. There have been many implant designs to replace the nucleus pulposus. Some researchers have proposed the replacement of the nucleus pulposus with hydrogel materials. The insertion of devices made from these materials further compromises the annulus of the disc. An ideal nucleus replacement could be injected into the disc space and form a solid in vivo. However, injectable replacements using curing elastomers and thermoplastic materials are not ideal because of the potentially harmful exothermic heat evolved from their reactions and the toxicity of the reactants used. We propose a hydrogel system that can be injected as a liquid at 25°C and solidified to yield a hydrogel within the intervertebral disc at 37°C. In aqueous solutions, these polymers have Lower Critical Solution Temperatures (LCST) between 25-37°C, making them unique candidate materials for this application. Poly(N-isopropylacrylamide) (PNIPAAm) is the most widely studied LCST polymer due to its drastic transition near body temperature. However, by itself, pure PNIPAAm forms a hydrogel that has low water content and can readily undergo plastic deformation. To increase the water content and impart elasticity to PNIPAAm hydrogels, grafted and branched hydrogel systems were created that incorporated the thermogelling PNIPAAm and hydrophilic poly(ethylene glycol) (PEG). In this research, the effects of polymer composition and monomer to initiator ratio, which controls polymer MW, on the in vitro swelling properties (mass, chemical, and compressive mechanical stability) of hydrogels formed from aqueous solutions of these polymers were evaluated. Immersion studies were also conducted in solutions to simulate the osmotic environment of the nucleus pulposus. The effects of repeated compression and unloading cycles

  3. Triple F - A Comet Nucleus Sample Return Mission

    NASA Technical Reports Server (NTRS)

    Kueppers, Michael; Keller, Horst Uwe; Kuhrt, Ekkehard; A'Hearn, Michael; Altwegg, Kathrin; Betrand, Regis; Busemann, Henner; Capria, Maria Teresa; Colangeli, Luigi

    2008-01-01

    The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA s Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three samples of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.

  4. Coulomb Excitation of the N = 50 nucleus 80Zn

    NASA Astrophysics Data System (ADS)

    van de Walle, J.; Aksouh, F.; Ames, F.; Behrens, T.; Bildstein, V.; Blazhev, A.; Cederkäll, J.; Clément, E.; Cocolios, T. E.; Davinson, T.; Delahaye, P.; Eberth, J.; Ekström, A.; Fedorov, D. V.; Fedosseev, V. N.; Fraile, L. M.; Franchoo, S.; Gernhauser, R.; Georgiev, G.; Habs, D.; Heyde, K.; Huber, G.; Huyse, M.; Ibrahim, F.; Ivanov, O.; Iwanicki, J.; Jolie, J.; Kester, O.; Köster, U.; Kröll, T.; Krücken, R.; Lauer, M.; Lisetskiy, A. F.; Lutter, R.; Marsh, B. A.; Mayet, P.; Niedermaier, O.; Nilsson, T.; Pantea, M.; Perru, O.; Raabe, R.; Reiter, P.; Sawicka, M.; Scheit, H.; Schrieder, G.; Schwalm, D.; Seliverstov, M. D.; Sieber, T.; Sletten, G.; Smirnova, N.; Stanoiu, M.; Stefanescu, I.; Thomas, J.-C.; Valiente-Dobón, J. J.; van Duppen, P.; Verney, D.; Voulot, D.; Warr, N.; Weisshaar, D.; Wenander, F.; Wolf, B. H.; Zielińska, M.

    2008-05-01

    Neutron rich Zinc isotopes, including the N = 50 nucleus 80Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2+ states. For the first time, an excited state in 80Zn was observed and the 21+ state in 78Zn was established. The measured B(E2,21+-->01+) values are compared to two sets of large scale shell model calculations. Both calculations reproduce the observed B(E2) systematics for the full Zinc isotopic chain. The results for N = 50 isotones indicate a good N = 50 shell closure and a strong Z = 28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni.

  5. The identification of musical instruments through nucleus cochlear implants.

    PubMed

    Grasmeder, M L; Lutman, M E

    2006-09-01

    In this study, self-reported ability to recognize musical instruments was investigated by means of a questionnaire, which was sent to a group of adult Nucleus cochlear implant users and a group of normally hearing subjects. In addition, spectrograms and electrodograms were produced and analysed for samples of music played on 10 different musical instruments. Self-reported ability to recognize some instruments was poor in the group of implant users, particularly for the saxophone, tuba and clarinet. Electrodograms showed that these instruments could only be identified using distorted spectral information or reduced temporal information. Other instruments, such as the drum and piano, could be identified using temporal information. Limited spectral resolution makes the recognition of musical instruments difficult for Nucleus implant users.

  6. Regulated chromosomal DNA replication in the absence of a nucleus.

    PubMed

    Walter, J; Sun, L; Newport, J

    1998-03-01

    Using Xenopus egg extracts, we have developed a completely soluble system for eukaryotic chromosomal DNA replication. In the absence of a nuclear envelope, a single, complete round of ORC-dependent DNA replication is catalyzed by cytosolic and nuclear extracts added sequentially to demembranated sperm chromatin or prokaryotic plasmid DNA. The absence of rereplication is explained by an activity present in the nucleus that prevents the binding of MCM to chromatin. Our results indicate that the role of the nuclear envelope in DNA replication is to concentrate activators and inhibitors of replication inside the nucleus. In addition, they provide direct evidence that metazoans use the same strategy as yeast to activate DNA replication and to restrict it to a single round per cell cycle.

  7. Cell Autonomy and Synchrony of Suprachiasmatic Nucleus Circadian Oscillators

    PubMed Central

    Mohawk, Jennifer A.; Takahashi, Joseph S.

    2013-01-01

    The suprachiasmatic nucleus (SCN) of the hypothalamus is the site of the master circadian pacemaker in mammals. The individual cells of the SCN are capable of functioning independently from one another and therefore must form a cohesive circadian network through intercellular coupling. The network properties of the SCN lead to coordination of circadian rhythms among its neurons and neuronal subpopulations. There is increasing evidence for multiple interconnected oscillators within the SCN, and in this Review, we will highlight recent advances in our understanding of the complex organization and function of the cellular and network-level SCN clock. Understanding the way in which synchrony is achieved between cells in the SCN will provide insight into the means by which this important nucleus orchestrates circadian rhythms throughout the organism. PMID:21665298

  8. Progressive activation of paratrigeminal nucleus during entrance to hibernation

    SciTech Connect

    Kilduff, T.S.; Sharp, F.R.; Heller, H.C. Univ. of California, San Francisco Veterans Administration Medical Center, San Francisco, CA )

    1988-07-01

    The paratrigeminal nucleus (Pa5) undergoes a progressive increase in its uptake of 2-({sup 14}C)deoxyglucose (2DG) relative to other brain structures during entrance to hibernation in the ground squirrel. This highly significant increase results in the Pa5 becoming the most highly labeled brain region during hibernation, even though it exhibits one of the lowest levels of 2DG uptake in the brain during the nonhibernating state. The progressive activation of the Pa5 observed during entrance is reversed during arousal from hibernation. These observations and the neuroanatomical projections of the Pa5 implicate this nucleus as playing a role in the entrance and maintenance of the hibernating state.

  9. Triple F - A Comet Nucleus Sample Return Mission

    NASA Technical Reports Server (NTRS)

    Kueppers, Michael; Keller, H. U.; Kuehrt, E.; A'Hearn, M. F.; Altwegg, K.; Bertrand, R.; Busemann, H.; Capria, M. T.; Colangeli, L.; Davidsson, B.; Ehrenfreund, P.; Knollenberg, J.; Mottola, S.; Weiss, P.; Zolensky, M.; Akim, E.; Basilevsky, A.; Galimov, E.; Gerasimov, M.; Korablev, O.; Charnley, S.; Nittler, L. R.; Sandford, S.; Weissman, P.

    2008-01-01

    The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA's Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-andgo sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.

  10. Maps of interaural delay in the owl's nucleus laminaris.

    PubMed

    Carr, Catherine E; Shah, Sahil; McColgan, Thomas; Ashida, Go; Kuokkanen, Paula T; Brill, Sandra; Kempter, Richard; Wagner, Hermann

    2015-09-01

    Axons from the nucleus magnocellularis form a presynaptic map of interaural time differences (ITDs) in the nucleus laminaris (NL). These inputs generate a field potential that varies systematically with recording position and can be used to measure the map of ITDs. In the barn owl, the representation of best ITD shifts with mediolateral position in NL, so as to form continuous, smoothly overlapping maps of ITD with iso-ITD contours that are not parallel to the NL border. Frontal space (0°) is, however, represented throughout and thus overrepresented with respect to the periphery. Measurements of presynaptic conduction delay, combined with a model of delay line conduction velocity, reveal that conduction delays can account for the mediolateral shifts in the map of ITD. PMID:26224776

  11. Organotypic slice culture of the hypothalamic paraventricular nucleus of rat

    PubMed Central

    Cho, Eun Seong; Lee, So Yeong; Park, Jae-Yong; Hong, Seong-Geun

    2007-01-01

    Organotypic slice cultures have been developed as an alternative to acute brain slices because the neuronal viability and synaptic connectivity in these cultures can be preserved well for a prolonged period of time. This study evaluated a stationary organotypic slice culture developed for the hypothalamic paraventricular nucleus (PVN) of rat. The results showed that the slice cultures maintain the typical shape of the nucleus, the immunocytochemical signals for oxytocin, vasopressin, and corticotropin-releasing hormone, and the electrophysiological properties of PVN neurons for up to 3 weeks in vitro. The PVN neurons in the culture expressed the green fluorescent protein gene that had been delivered by the adenoviral vectors. The results indicate that the cultured slices preserve the properties of the PVN neurons, and can be used in longterm studies on these neurons in vitro. PMID:17322769

  12. Structure in the nucleus of NGC 1068 at 10 microns

    NASA Technical Reports Server (NTRS)

    Tresch-Fienberg, R.; Fazio, G. G.; Gezari, D. Y.; Lamb, G. M.; Shu, P. K.; Hoffmann, W. F.; Mccreight, C. R.

    1987-01-01

    New 8-13 micron array camera images of the central kiloparsec of Seyfert 2 galaxy NGC 1068 resolve structure that is similar to that observed at visible and radio wavelengths. The images reveal an infrared source which is extended and asymmetric, with its long axis oriented at P.A. 33 deg. Maps of the spatial distribution of 8-13 micron color temperature and warm dust opacity are derived from the multiwavelength infrared images. The results suggest that there exist two pointlike luminosity sources in the central region of NGC 1068, with the brighter source at the nucleus and the fainter one some 100 pc to the northeast. This geometry strengthens the possibility that the 10 micron emission observed from grains in the nucleus is powered by a nonthermal source. In the context of earlier visible and radio studies, these results considerably strengthen the case for jet-induced star formation in NGC 1068.

  13. Structure in the nucleus of NGC 1068 at 10 microns

    NASA Technical Reports Server (NTRS)

    Tresch-Fienberg, R.; Fazio, G. G.; Gezari, D. Y.; Hoffmann, W. F.; Lamb, G. M.; Shu, P. K.; Mccreight, C. R.

    1987-01-01

    New 8 to 13 micron array camera images of the central kiloparsec of Seyfert 2 galaxy NGC 1068 resolve structure that is similar to that observed at visible and radio wavelengths. The images reveal an infrared source which is extended and asymmetric, with its long axis oriented at P.A. 33 deg. Maps of the spatial distribution of 8 to 13 micron color temperature and warm dust opacity are derived from the multiwavelength infrared images. The results suggest that there exist two pointlike luminosity sources in the central regions of NGC 1068, with the brighter source at the nucleus and the fainter one some 100 pc to the northeast. This geometry strengthens the possibility that the 10 micron emission observed from grains in the nucleus is powered by a nonthermal source. In the context of earlier visible and radio studies, these results considerably strengthen the case for jet induced star formation in NGC 1068.

  14. Velocity dispersions in galaxies. IV - The nucleus of NGC 1068

    NASA Technical Reports Server (NTRS)

    Richstone, D. O.; Morton, D. C.

    1975-01-01

    A high-resolution spectrum of the Seyfert galaxy NGC 1068, obtained with an integrating television system, is compared with the spectrum of a KO III star (delta Tau) to derive the line-of-sight velocity dispersion of the stars in the galactic nucleus. An Fe I absorption line observed at 4059.7 A yields a velocity dispersion of 150 (plus or minus 50) km/sec. An upper limit for the nuclear mass is derived in terms of this velocity dispersion, an estimated nuclear radius of 136 pc, and a Hubble constant of 50 km/sec per Mpc. The results, 14 (+10, -8) by 10 to the 8th power solar masses, is shown to be consistent with a number of quasar models scaled down in luminosity to provide the energy source for a Seyfert nucleus. Strong H and K interstellar absorption lines superposed on the spectrum of NGC 1068 are analyzed.-

  15. Volume regulation and shape bifurcation in the cell nucleus.

    PubMed

    Kim, Dong-Hwee; Li, Bo; Si, Fangwei; Phillip, Jude M; Wirtz, Denis; Sun, Sean X

    2015-09-15

    Alterations in nuclear morphology are closely associated with essential cell functions, such as cell motility and polarization, and correlate with a wide range of human diseases, including cancer, muscular dystrophy, dilated cardiomyopathy and progeria. However, the mechanics and forces that shape the nucleus are not well understood. Here, we demonstrate that when an adherent cell is detached from its substratum, the nucleus undergoes a large volumetric reduction accompanied by a morphological transition from an almost smooth to a heavily folded surface. We develop a mathematical model that systematically analyzes the evolution of nuclear shape and volume. The analysis suggests that the pressure difference across the nuclear envelope, which is influenced by changes in cell volume and regulated by microtubules and actin filaments, is a major factor determining nuclear morphology. Our results show that physical and chemical properties of the extracellular microenvironment directly influence nuclear morphology and suggest that there is a direct link between the environment and gene regulation.

  16. Theoretical description of the decay chain of the nucleus 294118

    NASA Astrophysics Data System (ADS)

    Sobiczewski, Adam

    2016-09-01

    The decay chain of the nucleus 294118, the heaviest nucleus observed (at JINR-Dubna) up to now, is analyzed theoretically. The α-decay energies {Q}α , the α-decay and the spontaneous-fission half-lives, {T}α and {T}{{sf}}, are studied. The analysis of the α decay is based on a phenomenological model using only three parameters. The calculations are performed in three variants using masses obtained with three nuclear-mass models accurately describing masses of heaviest nuclei. The experimental {Q}α energies are reconstructed with the average of the absolute values of the discrepancies: 180 keV, 270 keV and 290 keV, in the three variants considered. Measured half-lives {T}α are reproduced within the average ratios: 2.9, 9.8 and 5.2 in these variants.

  17. Neutrino-nucleus interactions at the LBNF near detector

    SciTech Connect

    Mosel, Ulrich

    2015-10-15

    The reaction mechanisms for neutrino interactions with an {sup 40}Ar nucleus with the LBNF flux are calculated with the Giessen-Boltzmann-Uehling-Uhlenbeck (GiBUU) transport-theoretical implementation of these interactions. Quasielastic scattering, many-body effects, pion production and absorption and Deep Inelastic Scattering are discussed; they all play a role at the LBNF energies and are experimentally entangled with each other. Quasielastic scattering makes up for only about 1/3 of the total cross section whereas pion production channels make up about 2/3 of the total. This underlines the need for a consistent description of the neutrino-nucleus reaction that treats all channels on an equal, consistent footing. The results discussed here can also serve as useful guideposts for the Intermediate Neutrino Program.

  18. Maps of interaural delay in the owl's nucleus laminaris

    PubMed Central

    Shah, Sahil; McColgan, Thomas; Ashida, Go; Kuokkanen, Paula T.; Brill, Sandra; Kempter, Richard; Wagner, Hermann

    2015-01-01

    Axons from the nucleus magnocellularis form a presynaptic map of interaural time differences (ITDs) in the nucleus laminaris (NL). These inputs generate a field potential that varies systematically with recording position and can be used to measure the map of ITDs. In the barn owl, the representation of best ITD shifts with mediolateral position in NL, so as to form continuous, smoothly overlapping maps of ITD with iso-ITD contours that are not parallel to the NL border. Frontal space (0°) is, however, represented throughout and thus overrepresented with respect to the periphery. Measurements of presynaptic conduction delay, combined with a model of delay line conduction velocity, reveal that conduction delays can account for the mediolateral shifts in the map of ITD. PMID:26224776

  19. The cellular mastermind(?) – Mechanotransduction and the nucleus

    PubMed Central

    Kaminski, Ashley; Fedorchak, Gregory R.; Lammerding, Jan

    2015-01-01

    Cells respond to mechanical stimulation by activation of specific signaling pathways and genes that allow the cell to adapt to its dynamic physical environment. How cells sense the various mechanical inputs and translate them into biochemical signals remains an area of active investigation. Recent reports suggest that the cell nucleus may be directly implicated in this cellular mechanotransduction process. In this chapter, we discuss how forces applied to the cell surface and cytoplasm induce changes in nuclear structure and organization, which could directly affect gene expression, while also highlighting the complex interplay between nuclear structural proteins and transcriptional regulators that may further modulate mechanotransduction signaling. Taken together, these findings paint a picture of the nucleus as a central hub in cellular mechanotransduction—both structurally and biochemically—with important implications in physiology and disease. PMID:25081618

  20. Towards a Deeper Understanding of the Nucleus with Exotic Nuclei

    NASA Astrophysics Data System (ADS)

    Ormand, Erich

    2006-10-01

    Despite more than fifty years of study, many questions about now nuclei are put together remain. While nuclei near the valley of stability have provided a wealth of information, they are not sufficient to provide us with a comprehensive and unified description of the nucleus. Especially lacking is an accurate picture of those exotic species that are the basis of cosmic alchemy. The missing pieces in the puzzle can be filled in with a determined experimental and theoretical effort focusing on nuclei lying far from the valley of stability. Here, I will outline the intellectual challenges that can be addressed by proposed exotic-beam facilities, and how new experimental data will quide and refine theoretical descriptions of the nucleus.

  1. K+-nucleus potentials from K+-nucleon amplitudes

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    2016-10-01

    Optical potentials for K+-nucleus interactions are constructed from K+-nucleon amplitudes using recently developed algorithm based on K+-N kinematics in the nuclear medium. With the deep penetration of K+ mesons into the nucleus at momenta below 800 MeV / c it is possible to test this approach with greater sensitivity than hitherto done with K- and pions. The energy-dependence of experimental reaction and total cross sections on nuclei is better reproduced with this approach compared to fixed-energy amplitudes. The inclusion of Pauli correlations in the medium also improves the agreement between calculation and experiment. The absolute scale of the cross sections is reproduced very well for 6Li but for C, Si and Ca calculated cross sections are (23 ± 4)% smaller than experiment, in agreement with earlier analyses. Two phenomenological models that produce such missing strength suggest that the imaginary part of the potential needs about 40% enhancement.

  2. IC5063: A merger with a hidden luminous active nucleus

    NASA Technical Reports Server (NTRS)

    Colina, L.; Sparks, W. B.; Macchetto, F. D.

    1990-01-01

    IC5063 is a nearby galaxy classified as an SO and containing a system of dust lanes parallel to its major optical axis (Danziger, Goss and Wellington, 1981; Bergeron, Durret and Boksenberg, 1983). Extended emission line regions with high excitation properties have been detected over distances of up to 19 kpc from the nucleus. This galaxy has been classified as Seyfert 2 on the basis of its emission line spectrum. These characteristics make IC5063 one of the best candidates for a merger remnant and an excellent candidate for a hidden luminous active nucleus. Based on new broad and narrow band images and long-slit spectroscopy obtained at the ESO 3.6 m telescope, the authors present some preliminary results supporting this hypothesis.

  3. Doubly magic nucleus (108)(270)Hs162.

    PubMed

    Dvorak, J; Brüchle, W; Chelnokov, M; Dressler, R; Düllmann, Ch E; Eberhardt, K; Gorshkov, V; Jäger, E; Krücken, R; Kuznetsov, A; Nagame, Y; Nebel, F; Novackova, Z; Qin, Z; Schädel, M; Schausten, B; Schimpf, E; Semchenkov, A; Thörle, P; Türler, A; Wegrzecki, M; Wierczinski, B; Yakushev, A; Yeremin, A

    2006-12-15

    Theoretical calculations predict 270Hs (Z=108, N=162) to be a doubly magic deformed nucleus, decaying mainly by alpha-particle emission. In this work, based on a rapid chemical isolation of Hs isotopes produced in the 26Mg+248Cm reaction, we observed 15 genetically linked nuclear decay chains. Four chains were attributed to the new nuclide 270Hs, which decays by alpha-particle emission with Qalpha=9.02+/-0.03 MeV to 266Sg which undergoes spontaneous fission with a half-life of 444(-148)(+444) ms. A production cross section of about 3 pb was measured for 270Hs. Thus, 270Hs is the first nucleus for which experimental nuclear decay properties have become available for comparison with theoretical predictions of the N=162 shell stability. PMID:17280272

  4. Nucleus incertus inactivation impairs spatial learning and memory in rats.

    PubMed

    Nategh, Mohsen; Nikseresht, Sara; Khodagholi, Fariba; Motamedi, Fereshteh

    2015-02-01

    Nucleus incertus (NI) is a pontine nucleus which releases mainly GABA and relaxin-3 in rats. Its suggested functions include response to stress, arousal, and modulation of hippocampal theta rhythm. Since the role of NI in learning and memory has not been well characterized, therefore the involvement of this nucleus in spatial learning and memory and the aftermath hippocampal levels of c-fos and pCREB were evaluated. NI was targeted by implanting cannula in male rats. For reference memory, NI was inactivated by lidocaine (0.4 μl, 4%) at three stages of acquisition, consolidation and retrieval in Morris water maze paradigm. For working memory, NI was inactivated in acquisition and retrieval phases. Injection of lidocaine prior to the first training session of reference memory significantly increased the distance moved, suggesting that inactivation of NI delays acquisition in this spatial task. Inactivation also interfered with the retrieval phase of spatial reference memory, as the time in target quadrant for lidocaine group was less, and the escape latency was higher compared to the control group. However, no difference was observed in the consolidation phase. In the working memory task, with inter-trial intervals of 75 min, the escape latency was higher when NI was inactivated in the retrieval phase. In addition, c-fos and pCREB/CREB levels decreased in NI-inhibited rats. This study suggests that nucleus incertus might participate in acquisition of spatial reference, and retrieval of both spatial reference and working memory. Further studies should investigate possible roles of NI in the hippocampal plasticity.

  5. Analysis about the force of electrons revolve around the nucleus

    NASA Astrophysics Data System (ADS)

    Yongquan, Han

    1, Let's compare the difference of two algorithms: the electrostatic force between protons and electrons, F1 = ke2 / r2, r is the radius of the electron around the nucleus movement - within 10-10 meters; Electronic movement speed is close to the light- about 107 meters per second, the size of the centripetal force F2 = v2m/r. F1 should be approximately equal to F2,calculate the ratio of F1 and F2, F2 / F1 = (v2m/r) (ke2 / r2) / = (107 * 107 * 0.91 * 10-30 / r)/(9 * 109 * 1.6* 10-19*1.6*10-19 / r2) = 4 x 103.The calculation shows that not only the electrostatic force and other force. 2, The radius of the electron orbiting around the nucleus named r, F = Ke2 / r2 = 9 x 109 x #¨1.6 x 10 -19) 2 / r2 = v2m/r, r = 2.5 x 10-14 meters, namely that the radius of hydrogen atom is about 2.5 x 10- 14 meters, that is different with the observed result (10-10 meters).Electrons revolve around the nucleus may faster than 107 m/s, can almost reach 108 meters per second, if the electronic moves by 108 meters per second, hydrogen atom radius is approximately 2. 5 x 10 -16 meters, has converged in the interior of the nucleus, it is not possible. Use density to instead of electricity, can solve this problem. Author: hanyongquan TEL: 15611860790

  6. The Ionization Source in the Nucleus of M84

    NASA Technical Reports Server (NTRS)

    Bower, G. A.; Green, R. F.; Quillen, A. C.; Danks, A.; Malumuth, E. M.; Gull, T.; Woodgate, B.; Hutchings, J.; Joseph, C.; Kaiser, M. E.

    2000-01-01

    We have obtained new Hubble Space Telescope (HST) observations of M84, a nearby massive elliptical galaxy whose nucleus contains a approximately 1.5 X 10(exp 9) solar mass dark compact object, which presumably is a supermassive black hole. Our Space Telescope Imaging Spectrograph (STIS) spectrum provides the first clear detection of emission lines in the blue (e.g., [0 II] lambda 3727, HBeta and [0 III] lambda lambda4959,5007), which arise from a compact region approximately 0".28 across centered on the nucleus. Our Near Infrared Camera and MultiObject Spectrometer (NICMOS) images exhibit the best view through the prominent dust lanes evident at optical wavelengths and provide a more accurate correction for the internal extinction. The relative fluxes of the emission lines we have detected in the blue together with those detected in the wavelength range 6295 - 6867 A by Bower et al. indicate that the gas at the nucleus is photoionized by a nonstellar process, instead of hot stars. Stellar absorption features from cool stars at the nucleus are very weak. We update the spectral energy distribution of the nuclear point source and find that although it is roughly flat in most bands, the optical to UV continuum is very red, similar to the spectral energy distribution of BL Lac. Thus, the nuclear point source seen in high-resolution optical images is not a star cluster but is instead a nonstellar source. Assuming isotropic emission from this source, we estimate that the ratio of bolometric luminosity to Eddington luminosity is about 5 x 10(exp -7). However, this could be underestimated if this source is a misaligned BL Lac object, which is a possibility suggested by the spectral energy distribution and the evidence of optical variability we describe.

  7. Hidden Glashow resonance in neutrino-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Alikhanov, I.

    2016-05-01

    Today it is widely believed that s-channel excitation of an on-shell W boson, commonly known as the Glashow resonance, can be initiated in matter only by the electron antineutrino in the process νbaree- →W- at the laboratory energy around 6.3 PeV. In this Letter we argue that the Glashow resonance within the Standard Model also occurs in neutrino-nucleus collisions. The main conclusions are as follows. 1) The Glashow resonance can be excited by both neutrinos and antineutrinos of all the three flavors scattering in the Coulomb field of a nucleus. 2) The Glashow resonance in a neutrino-nucleus reaction does not manifest itself as a Breit-Wigner-like peak in the cross section but the latter exhibits instead a slow logarithmic-law growth with the neutrino energy. The resonance turns thus out to be hidden. 3) More than 98% of W bosons produced in the sub-PeV region in neutrino-initiated reactions in water/ice will be from the Glashow resonance. 4) The vast majority of the Glashow resonance events in a neutrino detector are expected at energies from a few TeV to a few tens of TeV, being mostly initiated by the conventional atmospheric neutrinos dominant in this energy range. Calculations of the cross sections for Glashow resonance excitation on the oxygen nucleus as well as on the proton are carried out in detail. The results of this Letter can be useful for studies of neutrino interactions at large volume water/ice neutrino detectors. For example, in the IceCube detector one can expect 0.3 Glashow resonance events with shower-like topologies and the deposited energies above 300 TeV per year. It is therefore likely already to have at least one Glashow resonance event in the IceCube data set.

  8. Study of Comet Nucleus Gamma-Ray Spectrometer Penetration System

    NASA Technical Reports Server (NTRS)

    Adams, G. L.; Amundsen, R. J.; Beardsley, R. W.; Cash, R. H.; Clark, B. C.; Knight, T. C. D.; Martin, J. P.; Monti, P.; Outteridge, D. A.; Plaster, W. D.

    1986-01-01

    A penetrator system has been suggested as an approach for making in situ measurements of the composition and physical properties of the nucleus of a comet. This study has examined in detail the feasibility of implementing the penetrator concept. The penetrator system and mission designs have been developed and iterated in sufficient detail to provide a high level of confidence that the concept can be implemented within the constraints of the Mariner Mark 2 spacecraft.

  9. Methods and compositions for targeting macromolecules into the nucleus

    DOEpatents

    Chook, Yuh Min

    2013-06-25

    The present invention includes compositions, methods and kits for directing an agent across the nuclear membrane of a cell. The present invention includes a Karyopherin beta2 translocation motif in a polypeptide having a slightly positively charged region or a slightly hydrophobic region and one or more R/K/H-X.sub.(2-5)-P-Y motifs. The polypeptide targets the agent into the cell nucleus.

  10. Neutrino magnetic moment effects in neutrino nucleus reactions

    SciTech Connect

    Singh, S.K.; Athar, M.S.

    1995-10-01

    Some low energy neutrino nucleus reactions induced by neutrinos (antineutrinos) having a magnetic moment of the order of 10{sup {minus}9}{minus}10{sup {minus}10} Bohr magneton are studied. It is found that in the case of {sup 4}He, {sup 12}C, and {sup 16}O, the detection of very low energy scalar and isoscalar elastic and inelastic reactions induced by the isoscalar vector currents can provide a better limit on the neutrino magnetic moment.

  11. Mechanics and deformation of the nucleus in micropipette aspiration experiment.

    PubMed

    Vaziri, Ashkan; Mofrad, Mohammad R Kaazempur

    2007-01-01

    Robust biomechanical models are essential for the study of nuclear mechanics and deformation and can help shed light on the underlying mechanisms of stress transition in nuclear elements. Here, we develop a computational model for an isolated nucleus undergoing micropipette aspiration. Our model includes distinct components representing the nucleoplasm and nuclear envelope. The nuclear envelope itself comprises three layers: inner and outer nuclear membranes and one thicker layer representing the nuclear lamina. The nucleoplasm is modeled as a viscoelastic Maxwell material with a single time constant, while a modified Maxwell model, equivalent to a spring and a dashpot in series and both in parallel with a spring, is adopted for the inner and outer nuclear membranes. The nuclear envelope layer is taken as a linear elastic material. The proposed computational model, validated using experimental observations of Guilak et al. [2000. Viscoelastic properties of the cell nucleus. Biochemical and Biophysical Research Communications 269, 781-786] and Deguchi et al. [2005, Flow-induced hardening of endothelial nucleus as an intracellular stress-bearing organelle. Journal of Biomechanics 38, 1751-1759], is employed to study nuclear mechanics and deformation in micropipette aspiration and to shed light on the contribution of individual nuclear components on the response. The results indicate that the overall response of an isolated nucleus in micropipette aspiration is highly sensitive to the apparent stiffness of the nuclear lamina. This observation suggests that micropipette aspiration is an effective technique for examining the influence of various kinds of alteration in the nuclear lamina, such as mutations in the gene encoding lamin A, and also structural remodeling due to mechanical perturbation.

  12. Mechanics and deformation of the nucleus in micropipette aspiration experiment.

    PubMed

    Vaziri, Ashkan; Mofrad, Mohammad R Kaazempur

    2007-01-01

    Robust biomechanical models are essential for the study of nuclear mechanics and deformation and can help shed light on the underlying mechanisms of stress transition in nuclear elements. Here, we develop a computational model for an isolated nucleus undergoing micropipette aspiration. Our model includes distinct components representing the nucleoplasm and nuclear envelope. The nuclear envelope itself comprises three layers: inner and outer nuclear membranes and one thicker layer representing the nuclear lamina. The nucleoplasm is modeled as a viscoelastic Maxwell material with a single time constant, while a modified Maxwell model, equivalent to a spring and a dashpot in series and both in parallel with a spring, is adopted for the inner and outer nuclear membranes. The nuclear envelope layer is taken as a linear elastic material. The proposed computational model, validated using experimental observations of Guilak et al. [2000. Viscoelastic properties of the cell nucleus. Biochemical and Biophysical Research Communications 269, 781-786] and Deguchi et al. [2005, Flow-induced hardening of endothelial nucleus as an intracellular stress-bearing organelle. Journal of Biomechanics 38, 1751-1759], is employed to study nuclear mechanics and deformation in micropipette aspiration and to shed light on the contribution of individual nuclear components on the response. The results indicate that the overall response of an isolated nucleus in micropipette aspiration is highly sensitive to the apparent stiffness of the nuclear lamina. This observation suggests that micropipette aspiration is an effective technique for examining the influence of various kinds of alteration in the nuclear lamina, such as mutations in the gene encoding lamin A, and also structural remodeling due to mechanical perturbation. PMID:17112531

  13. Theory and phenomenology of coherent neutrino-nucleus scattering

    SciTech Connect

    McLaughlin, Gail

    2015-07-15

    We review the theory and phenomenology of coherent elastic neutrino-nucleus scattering (CEνNS). After a brief introduction, we summarize the places where CEνNS is already in use and then turn to future physics opportunities from CEνNS. CEνNS has been proposed as a way to limit or discover beyond the standard model physics, measure the nuclear-neutron radius and constrain the Weinberg angle.

  14. The subthalamic nucleus. Part I: development, cytology, topography and connections.

    PubMed

    Marani, Enrico; Heida, Tjitske; Lakke, Egbert A J F; Usunoff, Kamen G

    2008-01-01

    This monograph (Part I of two volumes) on the subthalamic nucleus (STN) accentuates the gap between experimental animal and human information concerning subthalamic development, cytology, topography and connections. The light and electron microscopical cytology focuses on the open nucleus concept and the neuronal types present in the STN. The cytochemistry encompasses enzymes, NO, glial fibrillary acidic protein (GFAP), calcium binding proteins, and receptors (dopamine, cannabinoid, opioid, glutamate, gamma-aminobutyric acid (GABA), serotonin, cholinergic, and calcium channels). The ontogeny of the subthalamic cell cord is also reviewed. The topography concerns the rat, cat, baboon and human STN. The descriptions of the connections are also given from a historical point of view. Recent tracer studies on the rat nigro-subthalamic connection revealed contralateral projections. Part II of the two volumes (volume 199) on the subthalamic nucleus (STN) starts with a systemic model of the basal ganglia to evaluate the position of the STN in the direct, indirect and hyperdirect pathways. A summary of in vitro studies is given, describing STN spontaneous activity as well as responses to depolarizing and hyperpolarizing inputs and high-frequency stimulation. STN bursting activity and the underlying ionic mechanisms are investigated. Deep brain stimulation used for symptomatic treatment of Parkinson's disease is discussed in terms of the elements that are influenced and its hypothesized mechanisms. This part of the monograph explores the pedunculopontine-subthalamic connections and summarizes attempts to mimic neurotransmitter actions of the pedunculopontine nucleus in cell cultures and high-frequency stimulation on cultured dissociated rat subthalamic neurons. STN cell models--single- and multi-compartment models and system-level models are discussed in relation to subthalamic function and dysfunction. Parts I and II are compared. PMID:18727483

  15. The subthalamic nucleus part II: modelling and simulation of activity.

    PubMed

    Heida, Tjitske; Marani, Enrico; Usunoff, Kamen G

    2008-01-01

    Part I of The Subthalamic Nucleus (volume 198) (STN) accentuates the gap between experimental animal and human information concerning subthalamic development, cytology, topography and connections.The light and electron microscopical cytology focuses on the open nucleus concept and the neuronal types present in the STN. The cytochemistry encompasses enzymes, NO, glial fibrillary acidic protein (GFAP), calcium binding proteins, and receptors (dopamine, cannabinoid, opioid, glutamate, gamma-aminobutyric acid (GABA), serotonin, cholinergic, and calcium channels). The ontogeny of the subthalamic cell cord is also reviewed. The topography concerns the rat, cat, baboon and human STN. The descriptions of the connections are also given from a historical point of view. Recent tracer studies on the rat nigro-subthalamic connection revealed contralateral projections. This monograph (Part II of the two volumes) on the subthalamic nucleus (STN) starts with a systemic model of the basal ganglia to evaluate the position of the STN in the direct, indirect and hyperdirect pathways. A summary of in vitro studies is given, describing STN spontaneous activity as well as responses to depolarizing and hyperpolarizing inputs and high-frequency stimulation. STN bursting activity and the underlying ionic mechanisms are investigated. Deep brain stimulation used for symptomatic treatment of Parkinson's disease is discussed in terms of the elements that are influenced and its hypothesized mechanisms. This part of the monograph explores the pedunculopontine-subthalamic connections and summarizes attempts to mimic neurotransmitter actions of the pedunculopontine nucleus in cell cultures and high-frequency stimulation on cultured dissociated rat subthalamic neurons. STN cell models - single- and multi-compartment models and system-level models are discussed in relation to subthalamic function and dysfunction. Parts I and II are compared. PMID:18727495

  16. Emission of charged particles from excited compound nucleus

    SciTech Connect

    Kalandarov, Sh. A.; Adamian, G. G.; Antonenko, N. V.

    2010-11-24

    The formation and decay of excited compound nucleus are studied within the dinuclear system model[1]. The cross sections of complex fragment emission are calculated and compared with experimental data for the reactions {sup 3}He+{sup 108}Ag, {sup 78,82}Kr+{sup 12}C. Angular momentum dependence of cluster emission in {sup 78}Kr+{sup 12}C and {sup 40}Ca+{sup 78}Kr reactions is demonstrated.

  17. mRNA-Producing Pseudo-nucleus System.

    PubMed

    Shin, Seung Won; Park, Kyung Soo; Shin, Woo Jung; Um, Soong Ho

    2015-11-01

    A pseudo-eukaryotic nucleus (PEN) system consisting of a gene-containing DNA hydrogel encapsulated in a liposome is fabricated. Owing to the structural characteristics of gene-containing DNA hydrogel, mRNA transcription efficiency is promoted 2.57-fold. Through the use of PEN as a platform for mRNA delivery to the cytosol, prolonged protein translation is achieved. PMID:26310990

  18. AN OFF-CENTERED ACTIVE GALACTIC NUCLEUS IN NGC 3115

    SciTech Connect

    Menezes, R. B.; Steiner, J. E.; Ricci, T. V.

    2014-11-20

    NGC 3115 is an S0 galaxy that has always been considered to have a pure absorption-line spectrum. Some recent studies have detected a compact radio-emitting nucleus in this object, coinciding with the photometric center and with a candidate for the X-ray nucleus. This is evidence of the existence of a low-luminosity active galactic nucleus (AGN) in the galaxy, although no emission line has ever been observed. We report the detection of an emission-line spectrum of a type 1 AGN in NGC 3115, with an Hα luminosity of L {sub Hα} = (4.2 ± 0.4) × 10{sup 37} erg s{sup –1}. Our analysis revealed that this AGN is located at a projected distance of ∼0.''29 ± 0.''05 (corresponding to ∼14.3 ± 2.5 pc) from the stellar bulge center, which is coincident with the kinematic center of this object's stellar velocity map. The black hole corresponding to the observed off-centered AGN may form a binary system with a black hole located at the stellar bulge center. However, it is also possible that the displaced black hole is the merged remnant of the binary system coalescence, after the ''kick'' caused by the asymmetric emission of gravitational waves. We propose that certain features in the stellar velocity dispersion map are the result of perturbations caused by the off-centered AGN.

  19. Incorporation of mammalian actin into microfilaments in plant cell nucleus

    PubMed Central

    Paves, Heiti; Truve, Erkki

    2004-01-01

    Background Actin is an ancient molecule that shows more than 90% amino acid homology between mammalian and plant actins. The regions of the actin molecule that are involved in F-actin assembly are largely conserved, and it is likely that mammalian actin is able to incorporate into microfilaments in plant cells but there is no experimental evidence until now. Results Visualization of microfilaments in onion bulb scale epidermis cells by different techniques revealed that rhodamine-phalloidin stained F-actin besides cytoplasm also in the nuclei whereas GFP-mouse talin hybrid protein did not enter the nuclei. Microinjection of fluorescently labeled actin was applied to study the presence of nuclear microfilaments in plant cells. Ratio imaging of injected fluorescent rabbit skeletal muscle actin and phalloidin staining of the microinjected cells showed that mammalian actin was able to incorporate into plant F-actin. The incorporation occurred preferentially in the nucleus and in the perinuclear region of plant cells whereas part of plant microfilaments, mostly in the periphery of cytoplasm, did not incorporate mammalian actin. Conclusions Microinjected mammalian actin is able to enter plant cell's nucleus, whereas incorporation of mammalian actin into plant F-actin occurs preferentially in the nucleus and perinuclear area. PMID:15102327

  20. Dorsal raphe nucleus projecting retinal ganglion cells: Why Y cells?

    PubMed Central

    Pickard, Gary E.; So, Kwok-Fai; Pu, Mingliang

    2015-01-01

    Retinal ganglion Y (alpha) cells are found in retinas ranging from frogs to mice to primates. The highly conserved nature of the large, fast conducting retinal Y cell is a testament to its fundamental task, although precisely what this task is remained ill-defined. The recent discovery that Y-alpha retinal ganglion cells send axon collaterals to the serotonergic dorsal raphe nucleus (DRN) in addition to the lateral geniculate nucleus (LGN), medial interlaminar nucleus (MIN), pretectum and the superior colliculus (SC) has offered new insights into the important survival tasks performed by these cells with highly branched axons. We propose that in addition to its role in visual perception, the Y-alpha retinal ganglion cell provides concurrent signals via axon collaterals to the DRN, the major source of serotonergic afferents to the forebrain, to dramatically inhibit 5-HT activity during orientation or alerting/escape responses, which dis-facilitates ongoing tonic motor activity while dis-inhibiting sensory information processing throughout the visual system. The new data provide a fresh view of these evolutionarily old retinal ganglion cells. PMID:26363667

  1. An Automatic Learning-Based Framework for Robust Nucleus Segmentation.

    PubMed

    Xing, Fuyong; Xie, Yuanpu; Yang, Lin

    2016-02-01

    Computer-aided image analysis of histopathology specimens could potentially provide support for early detection and improved characterization of diseases such as brain tumor, pancreatic neuroendocrine tumor (NET), and breast cancer. Automated nucleus segmentation is a prerequisite for various quantitative analyses including automatic morphological feature computation. However, it remains to be a challenging problem due to the complex nature of histopathology images. In this paper, we propose a learning-based framework for robust and automatic nucleus segmentation with shape preservation. Given a nucleus image, it begins with a deep convolutional neural network (CNN) model to generate a probability map, on which an iterative region merging approach is performed for shape initializations. Next, a novel segmentation algorithm is exploited to separate individual nuclei combining a robust selection-based sparse shape model and a local repulsive deformable model. One of the significant benefits of the proposed framework is that it is applicable to different staining histopathology images. Due to the feature learning characteristic of the deep CNN and the high level shape prior modeling, the proposed method is general enough to perform well across multiple scenarios. We have tested the proposed algorithm on three large-scale pathology image datasets using a range of different tissue and stain preparations, and the comparative experiments with recent state of the arts demonstrate the superior performance of the proposed approach.

  2. Growth behavior of cochlear nucleus neuronal cells on semiconductor substrates.

    PubMed

    Rak, Kristen; Wasielewski, Natalia; Radeloff, Andreas; Scherzed, Agmal; Jablonka, Sibylle; Hagen, Rudolf; Mlynski, Robert

    2011-05-01

    Auditory brainstem implants provide sound information by direct stimulation of the cochlear nucleus to patients with dysfunctional or absent cranial nerve VIII. In contrast to patients with cochlear implants, the use of the auditory brainstem implants is less successful. This cannot be fully explained by the difference location of stimulation but a rather unspecific neuronal stimulation. The aim of this study was to further examine neuronal cells of the cochlear nucleus and to test their interactions with semiconductor substrates as a potential electrode material for improved auditory brainstem implants. The cochlear nuclei of postnatal day 7 rats were microsurgically dissected. The tissue was dissociated enzymatically and plated on coverslips as control and on the semiconductor substrates silicon or silicon nitride. After 4 days in culture the morphology and growth of dissociated cells was determined by fluorescence and scanning electron microscopy. Dissociated cells of the cochlear nucleus showed reduced cell growth on semiconductor substrates compared with controls. SEM analysis demonstrated close contact of neurons with supporting cells in culture and good adherence of neuronal growth cones on the used materials. These findings present basic knowledge for the development of neuron-electrode interfaces for future auditory brainstem implants. PMID:21370446

  3. Coulomb problem for a Z>Z_cr nucleus

    NASA Astrophysics Data System (ADS)

    Kuleshov, V. M.; Mur, V. D.; Narozhny, N. B.; Fedotov, A. M.; Lozovik, Yu E.; Popov, V. S.

    2015-08-01

    A closed-form equation is derived for the critical nucleus charge Z=Z_cr at which a discrete level with the Dirac quantum number touches the lower continuum of the Dirac equation solutions. For the Coulomb potential cut off rectangularly at the short distance r0 = R{\\hbar}/(mc), R \\ll {1}, the critical nucleus charge values are obtained for several values of κ and R. It is shown that the partial scattering matrix of elastic positron-nucleus scattering, Sκ = \\exp(2iδκ(\\varepsilon_p)), is also unitary for Z>Z_cr. For this range, the scattering phase δ κ (\\varepsilon _p) is calculated as a function of the positron energy E_p = \\varepsilonp mc2, as are the positions and widths of quasidiscrete levels corresponding to the scattering matrix poles. The implication is that the single-particle approximation for the Dirac equation is valid not only for Z but also for Z>Z_cr and that there is no spontaneous creation of e^+e^- pairs from the vacuum.

  4. Energetic communication between mitochondria and nucleus directed by catalyzed phosphotransfer

    PubMed Central

    Dzeja, Petras P.; Bortolon, Ryan; Perez-Terzic, Carmen; Holmuhamedov, Ekshon L.; Terzic, Andre

    2002-01-01

    Exchange of information between the nucleus and cytosol depends on the metabolic state of the cell, yet the energy-supply pathways to the nuclear compartment are unknown. Here, the energetics of nucleocytoplasmic communication was determined by imaging import of a constitutive nuclear protein histone H1. Translocation of H1 through nuclear pores in cardiac cells relied on ATP supplied by mitochondrial oxidative phosphorylation, but not by glycolysis. Although mitochondria clustered around the nucleus, reducing the distance for energy transfer, simple nucleotide diffusion was insufficient to meet the energetic demands of nuclear transport. Rather, the integrated phosphotransfer network was required for delivery of high-energy phosphoryls from mitochondria to the nucleus. In neonatal cardiomyocytes with low creatine kinase activity, inhibition of adenylate kinase-catalyzed phosphotransfer abolished nuclear import. With deficient adenylate kinase, nucleoside diphosphate kinase, which secures phosphoryl exchange between ATP and GTP, was unable to sustain nuclear import. Up-regulation of creatine kinase phosphotransfer, to mimic metabolic conditions of adult cardiac cells, rescued H1 import, suggesting a developmental plasticity of the cellular energetic system. Thus, mitochondrial oxidative phosphorylation coupled with phosphotransfer relays provides an efficient energetic unit in support of nuclear transport. PMID:12119406

  5. Electron Spin Resonance (ESR) studies of returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Tsay, Fun-Dow; Kim, Soon Sam; Liang, Ranty H.

    1989-01-01

    The most important objective of the Comet Nucleus Sample Returm Mission is to return samples which could reflect formation conditions and evolutionary processes in the early solar nebula. It is expected that the returned samples will consist of fine-grained silicate materials mixed with ices composed of simple molecules such as H2O, NH3, CH4 as well as organics and/or more complex compounds. Because of the exposure to ionizing radiation from cosmic-ray, gamma-ray, and solar wind protons at low temperature, free radicals are expected to be formed and trapped in the solid ice matrices. The kind of trapped radical species together with their concentration and thermal stability can be used as a dosimeter as well as a geothermometer to determine thermal and radiation histories as well as outgassing and other possible alternation effects since the nucleus material was formed. Since free radicals that are known to contain unpaired electrons are all paramagnetic in nature, they can be readily detected and characterized in their native form by the Electron Spin Resonance (ESR) method. In fact, ESR has been shown to be a non-destructive, highly sensitive tool for the detection and characterization of paramagnetic, ferromagnetic, and radiation damage centers in terrestrial and extraterrestrial geological samples. The potential use of ESR as an effective method in the study of returned comet nucleus samples, in particular, in the analysis of fine-grained solid state icy samples is discussed.

  6. Relief memory consolidation requires protein synthesis within the nucleus accumbens.

    PubMed

    Bruning, Johann E A; Breitfeld, Tino; Kahl, Evelyn; Bergado-Acosta, Jorge R; Fendt, Markus

    2016-06-01

    Relief learning refers to the association of a stimulus with the relief from an aversive event. The thus-learned relief stimulus then can induce, e.g., an attenuation of the startle response or approach behavior, indicating positive valence. Previous studies revealed that the nucleus accumbens is essential for the acquisition and retrieval of relief memory. Here, we ask whether the nucleus accumbens is also the brain site for consolidation of relief memory into a long-term form. In rats, we blocked local protein synthesis within the nucleus accumbens by local infusions of anisomycin at different time points during a relief conditioning experiment. Accumbal anisomycin injections immediately after the relief conditioning session, but not 4 h later, prevented the consolidation into long-term relief memory. The retention of already consolidated relief memory was not affected by anisomycin injections. This identifies a time window and site for relief memory consolidation. These findings should complement our understanding of the full range of effects of adverse experiences, including cases of their distortion in humans such as post-traumatic stress disorder and/or phobias. PMID:26792192

  7. Magnetic dipole excitations of the 163Dy nucleus

    NASA Astrophysics Data System (ADS)

    Zenginerler, Zemine; Tabar, Emre; Yakut, Hakan; Kuliev, Ali Akbar; Guliyev, Ekber

    2014-03-01

    In this study some properties of the magnetic dipole excitations of the deformed odd mass 163Dy nucleus were studied by using Quasiparticle-phonon nuclear model (QPNM). The several of the ground-state and low-lying magnetic dipole (M1) mode characteristics were calculated for deformed odd-mass nuclei using a separable Hamiltonian within the QPNM. The M1 excited states, reduced transition probabilities B(M1), the ground-state magnetic properties such as magnetic moment (μ), intrinsic magnetic moment (gK) , effective spin factor (gseff.) are the fundamental characteristics of the odd-mass nucleus and provide key information to understand nuclear structure. The theoretical results were compared with the available experimental data and other theoretical approaches. Calculations show that the spin-spin interaction in this isotopes leads to polarization effect influencing the magnetic moments. Furthermore we found a strong fragmentation of the M1 strength in 163Dy nucleus which was in qualitative agreement with the experimental data. Sakarya University, Project Number: 2012-50-02-007 and Z.Zenginerler acknowledge to TUBITAK-TURKEY 2013, fellowship No: 2219.

  8. Experimental studies of pion-nucleus interactions at intermediate energies

    SciTech Connect

    Not Available

    1991-12-31

    This report summarizes the work on experimental research in intermediate energy nuclear physics carried out at New Mexico State University in 1991 under a great from the US Department of Energy. Most of these studies have involved investigations of various pion-nucleus interactions. The work has been carried out both with the LAMPF accelerator at the Los Alamos National Laboratory and with the cyclotron at the Paul Scherrer Institute (PSI) near Zurich, Switzerland. Part of the experimental work involves measurements of new data on double-charge-exchange scattering, using facilities at LAMPF which we helped modify, and on pion absorption, using a new detector system at PSI that covers nearly the full solid-angle region which we helped construct. Other work involved preparation for future experiments using polarized nuclear targets and a new high-resolution spectrometer system for detecting {pi}{sup 0} mesons. We also presented several proposals for works to be done in future years, involving studies related to pi-mesonic atoms, fundamental pion-nucleon interactions, studies of the difference between charged and neutral pion interactions with the nucleon, studies of the isospin structure of pion-nucleus interactions, and pion scattering from polarized {sup 3}He targets. This work is aimed at improving our understanding of the pion-nucleon interaction, of the pion-nucleus interaction mechanism, and of nuclear structure.

  9. Chemical anatomy of the human paraventricular thalamic nucleus.

    PubMed

    Uroz, Victoria; Prensa, Lucía; Giménez-Amaya, José Manuel

    2004-03-01

    The paraventricular thalamic nucleus (Pa) lies in the most medial aspect of the thalamus and is considered one of the midline thalamic nuclei. In the present study, we carried out histochemical and immunohistochemical procedures in the Pa of normal individuals to visualize the pattern of distribution of acetylcholinesterase (AChE), calbindin D-28k (CB), parvalbumin (PV), calretinin (CR), limbic system-associated membrane protein (LAMP), substance P (SP), and enkephalin (ENK). Other cytoarchitectural and myeloarchitectural techniques, such as Nissl and Gallyas, were also employed to delineate the boundaries of the Pa. The main findings of this study are: 1) AChE staining in the Pa was heterogeneously distributed along its anteroposterior and mediolateral axes; 2) the Pa harbored numerous CB- and CR-immunoreactive (ir) cells and neuropil, but this nucleus was largely devoid of PV; 3) the Pa was highly enriched in LAMP and this protein appeared uniformly distributed through its whole extent; and, 4) the SP and ENK immunoreactivities in the Pa revealed numerous highly varicose fibers scattered throughout this nucleus, but no stained cells. This morphological study demonstrates that the Pa is a heterogeneous chemical structure in humans. The functional significance of these results is discussed in the light of similar data gathered in several mammalian species.

  10. By moonlighting in the nucleus, villin regulates epithelial plasticity

    PubMed Central

    Patnaik, Srinivas; George, Sudeep P.; Pham, Eric; Roy, Swati; Singh, Kanchan; Mariadason, John M.; Khurana, Seema

    2016-01-01

    Villin is a tissue-specific, actin-binding protein involved in the assembly and maintenance of microvilli in polarized epithelial cells. Conversely, villin is also linked with the loss of epithelial polarity and gain of the mesenchymal phenotype in migrating, invasive cells. In this study, we describe for the first time how villin can switch between these disparate functions to change tissue architecture by moonlighting in the nucleus. Our study reveals that the moonlighting function of villin in the nucleus may play an important role in tissue homeostasis and disease. Villin accumulates in the nucleus during wound repair, and altering the cellular microenvironment by inducing hypoxia increases the nuclear accumulation of villin. Nuclear villin is also associated with mouse models of tumorigenesis, and a systematic analysis of a large cohort of colorectal cancer specimens confirmed the nuclear distribution of villin in a subset of tumors. Our study demonstrates that nuclear villin regulates epithelial–mesenchymal transition (EMT). Altering the nuclear localization of villin affects the expression and activity of Slug, a key transcriptional regulator of EMT. In addition, we find that villin directly interacts with a transcriptional corepressor and ligand of the Slug promoter, ZBRK1. The outcome of this study underscores the role of nuclear villin and its binding partner ZBRK1 in the regulation of EMT and as potential new therapeutic targets to inhibit tumorigenesis. PMID:26658611

  11. Coexistence of central nucleus, cores, and rods: Diagnostic relevance

    PubMed Central

    Dhinakaran, Sathiyabama; Kumar, Rashmi Santhosh; Thakkar, Ravindra; Narayanappa, Gayathri

    2016-01-01

    Background: Congenital myopathies (CMs) though considered distinct disorders, simultaneous occurrence of central nucleus, nemaline rods, and cores in the same biopsy are scarcely reported. Objective: A retrospective reassessment of cases diagnosed as CMs to look for multiple pathologies missed, if any, during the initial diagnosis. Materials and Methods: Enzyme histochemical, and immunohistochemical-stained slides from 125 cases diagnosed as congenital myopathy were reassessed. Results: The study revealed 15 cases (12%) of congenital myopathy with more than one morphological feature. Central nucleus with cores (n = 11), central nucleus, nemaline rods and cores (n = 3), and nemaline rods with cores (n = 1). 4/11 cases were diagnosed as centronuclear myopathy (CNM) in the first instance; in addition, cores were revealed on reassessment. Discussion: The prevalence of CMs of all neuromuscular disorders is approximately 6 in 100,000 live births, with regional variations. Three main defined CMs include centro nuclear myopathy (CNM), nemaline rod myopathy (NRM), and central core disease (CCD). However, they are more diverse with overlapping clinical and histopathological features, thus broadening the spectra within each category of congenital myopathy. Conclusion: Identification of cases with overlap of pathological features has diagnostic relevance. PMID:27293330

  12. Action at a Distance in the Cell's Nucleus

    NASA Astrophysics Data System (ADS)

    Kondev, Jane

    Various functions performed by chromosomes involve long-range communication between DNA sequences that are tens of thousands of bases apart along the genome, and microns apart in the nucleus. In this talk I will discuss experiments and theory relating to two distinct modes of long-range communication in the nucleus, chromosome looping and protein hopping along the chromosome, both in the context of DNA-break repair in yeast. Yeast is an excellent model system for studies that link chromosome conformations to their function as there is ample experimental evidence that yeast chromosome conformations are well described by a simple, random-walk polymer model. Using a combination of polymer physics theory and experiments on yeast cells, I will demonstrate that loss of polymer entropy due to chromosome looping is the driving force for homology search during repair of broken DNA by homologous recombination. I will also discuss the spread of histone modifications along the chromosome and away from the DNA break point in the context of simple physics models based on chromosome looping and kinase hopping, and show how combining physics theory and cell-biology experiment can be used to dissect the molecular mechanism of the spreading process. These examples demonstrate how combined theoretical and experimental studies can reveal physical principles of long-range communication in the nucleus, which play important roles in regulation of gene expression, DNA recombination, and chromatin modification. This work was supported by the NSF DMR-1206146.

  13. Hadron multiplicities and chemical freeze-out conditions in proton-proton and nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Vovchenko, V.; Begun, V. V.; Gorenstein, M. I.

    2016-06-01

    New results of the NA61/SHINE Collaboration at the CERN SPS on mean hadron multiplicities in proton-proton (p+p) interactions are analyzed within the transport models and the hadron resonance gas (HRG) statistical model. The chemical freeze-out parameters in p+p interactions and central Pb+Pb (or Au+Au) collisions are found and compared with each other in the range of the center-of-mass energy of the nucleon pair √{sN N}=3.2 -17.3 GeV. The canonical ensemble formulation of the HRG model is used to describe mean hadron multiplicities in p+p interactions and the grand canonical ensemble in central Pb+Pb and Au+Au collisions. The chemical freeze-out temperatures in p+p interactions are found to be larger than the corresponding temperatures in central nucleus-nucleus collisions.

  14. Neuronal relationships between the dorsal periaqueductal nucleus and the inferior colliculus (nucleus commissuralis) in the cat. A Golgi study.

    PubMed

    Herrera, M; Sánchez del Campo, F; Ruiz, A; Smith Agreda, V

    1988-06-01

    Cell types in the dorsal periaqueductal nucleus (PAGd) were studied with the aid of the rapid Golgi method in young cats. The neurons were subdivided into fusiform and stellate types with several varieties of the latter class according to the final destination of their axons. Fusiform neurons send their axons to the neuropil of the Ncom. In turn these neurons receive descending fibres from the nucleus commissuralis (Ncom) which seem to establish axo-dendritic contacts. Also commissural neurons receive contacts from ascending fibres of the PAGd. On the basis of Golgi material it is concluded that particular neuronal types of the PAGd could establish reciprocal connections with neuronal elements of the ventral part of the Ncom. The present study supports the hypothesis that the PAGd could be subdivided into discrete cell groups according to their afferent and efferent projections.

  15. Nucleus-encoded periplastid-targeted EFL in chlorarachniophytes.

    PubMed

    Gile, Gillian H; Keeling, Patrick J

    2008-09-01

    Chlorarachniophytes are cercozoan amoeboflagellates that acquired photosynthesis by enslaving a green alga, which has retained a highly reduced nucleus called a nucleomorph. The nucleomorph lacks many genes necessary for its own maintenance and expression, suggesting that some genes have been moved to the host nucleus and their products are now targeted back to the periplastid compartment (PPC), the reduced eukaryotic cytoplasm of the endosymbiont. Protein trafficking in chlorarachniophytes is therefore complex, including nucleus-encoded plastid-targeted proteins, nucleomorph-encoded plastid-targeted proteins, and nucleus-encoded periplastid-targeted proteins. A major gap in our understanding of this system is the PPC-targeted proteins because none have been described in any chlorarachniophytes. Here we describe the first such protein, the GTPase EFL. EFL was characterized from 7 chlorarachniophytes, and 2 distinct types were found. One is related to foraminiferan EFL and lacks an amino-terminal extension. The second, distantly related, type encodes an amino-terminal extension consisting of a signal peptide followed by sequence sharing many characteristics with transit peptides from nucleus-encoded plastid-targeted proteins and which we conclude is most likely PPC targeted. Western blotting with antibodies specific to putative host and PPC-targeted EFL from the chlorarachniophytes Bigelowiella natans and Gymnochlora stellata is consistent with posttranslational cleavage of the leaders from PPC-targeted proteins. Immunolocalization of both proteins in B. natans confirmed the cytosolic location of the leaderless EFL and a distinct localization pattern for the PPC-targeted protein but could not rule out a plastid location (albeit very unlikely). We sought other proteins with a similar leader and identified a eukaryotic translation initiation factor 1 encoding a bipartite extension with the same properties. Transit peptide sequences were characterized from all 3

  16. Pion yields and the nature of kaon-pion ratios in high energy nucleus-nucleus collisons: models versus measurements

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; De, B.; Guptaroy, P.

    2001-08-01

    The pion densities and the nature of kaon-pion ratios offer two very prominent and crucial physical observables on which sufficient data for heavy nucleus collisions, to date, are available. In the light of two models - one purely phenomenological and the other with a sound dynamical basis - we would try to examine here the state of agreement between calculations and experimental results obtainable from the past and the latest measurements. Impact and implications of all these would also finally be spelt out.

  17. Superscaling in electron-nucleus scattering and its link to CC and NC QE neutrino-nucleus scattering

    SciTech Connect

    Barbaro, M. B.; Amaro, J. E.; Caballero, J. A.; González-Jiménez, R.; Donnelly, T. W.; Ivanov, M.; Udías, J. M.

    2015-05-15

    The superscaling approach (SuSA) to neutrino-nucleus scattering, based on the assumed universality of the scaling function for electromagnetic and weak interactions, is reviewed. The predictions of the SuSA model for bot CC and NC differential and total cross sections are presented and compared with the MiniBooNE data. The role of scaling violations, in particular the contribution of meson exchange currents in the two-particle two-hole sector, is explored.

  18. Cytoarchitecture and efferent projections of the nucleus incertus of the rat.

    PubMed

    Olucha-Bordonau, Francisco E; Teruel, Vicent; Barcia-González, Jorge; Ruiz-Torner, Amparo; Valverde-Navarro, Alfonso A; Martínez-Soriano, Francisco

    2003-09-01

    The nucleus incertus is located caudal to the dorsal raphe and medial to the dorsal tegmentum. It is composed of a pars compacta and a pars dissipata and contains acetylcholinesterase, glutamic acid decarboxylase, and cholecystokinin-positive somata. In the present study, anterograde tracer injections in the nucleus incertus resulted in terminal-like labeling in the perirhinal cortex and the dorsal endopyriform nucleus, the hippocampus, the medial septum diagonal band complex, lateral and triangular septum medial amygdala, the intralaminar thalamic nuclei, and the lateral habenula. The hypothalamus contained dense plexuses of fibers in the medial forebrain bundle that spread in nearly all nuclei. Labeling in the suprachiasmatic nucleus filled specifically the ventral half. In the midbrain, labeled fibers were observed in the interpeduncular nuclei, ventral tegmental area, periaqueductal gray, superior colliculus, pericentral inferior colliculus, pretectal area, the raphe nuclei, and the nucleus reticularis pontis oralis. Retrograde tracer injections were made in areas reached by anterogradely labeled fibers including the medial prefrontal cortex, hippocampus, amygdala, habenula, nucleus reuniens, superior colliculus, periaqueductal gray, and interpeduncular nuclei. All these injections gave rise to retrograde labeling in the nucleus incertus but not in the dorsal tegmental nucleus. These data led us to conclude that there is a system of ascending projections arising from the nucleus incertus to the median raphe, mammillary complex, hypothalamus, lateral habenula, nucleus reuniens, amygdala, entorhinal cortex, medial septum, and hippocampus. Many of the targets of the nucleus incertus were involved in arousal mechanisms including the synchronization and desynchronization of the theta rhythm.

  19. The nucleus is an intracellular propagator of tensile forces in NIH 3T3 fibroblasts.

    PubMed

    Alam, Samer G; Lovett, David; Kim, Dae In; Roux, Kyle J; Dickinson, Richard B; Lele, Tanmay P

    2015-05-15

    Nuclear positioning is a crucial cell function, but how a migrating cell positions its nucleus is not understood. Using traction-force microscopy, we found that the position of the nucleus in migrating fibroblasts closely coincided with the center point of the traction-force balance, called the point of maximum tension (PMT). Positioning of the nucleus close to the PMT required nucleus-cytoskeleton connections through linker of nucleoskeleton-to-cytoskeleton (LINC) complexes. Although the nucleus briefly lagged behind the PMT following spontaneous detachment of the uropod during migration, the nucleus quickly repositioned to the PMT within a few minutes. Moreover, traction-generating spontaneous protrusions deformed the nearby nucleus surface to pull the nuclear centroid toward the new PMT, and subsequent retraction of these protrusions relaxed the nuclear deformation and restored the nucleus to its original position. We propose that the protruding or retracting cell boundary transmits a force to the surface of the nucleus through the intervening cytoskeletal network connected by the LINC complexes, and that these forces help to position the nucleus centrally and allow the nucleus to efficiently propagate traction forces across the length of the cell during migration.

  20. A hypothalamic projection to the turtle red nucleus: an anterograde and retrograde tracing study.

    PubMed

    Herrick, J L; Keifer, J

    1997-10-01

    It is well known that the reptilian red nucleus lacks a descending motor cortical input to the red nucleus, but has a well-developed cerebellar input. The present study was undertaken to determine whether there is a descending rubral input that originates from the hypothalamus. Using an in vitro preparation from the turtle, injections of neurobiotin into the red nucleus resulted in retrograde labeling of neurons in the suprapeduncular nucleus of the hypothalamus. Injections of either neurobiotin or fluorescein dextran into the suprapeduncular nucleus resulted in anterograde labeling of axons and terminal boutons in the red nucleus. The majority of these terminations appeared to lie in the medial part of the red nucleus. These data have implications for the potential control of the somatic motor system of reptiles by limbic system inputs.

  1. Spatiotemporal profiles of arginine vasopressin transcription in cultured suprachiasmatic nucleus.

    PubMed

    Yoshikawa, Tomoko; Nakajima, Yoshihiro; Yamada, Yoshiko; Enoki, Ryosuke; Watanabe, Kazuto; Yamazaki, Maya; Sakimura, Kenji; Honma, Sato; Honma, Ken-ichi

    2015-11-01

    Arginine vasopressin (AVP), a major neuropeptide in the suprachiasmatic nucleus (SCN), is postulated to mediate the output of the circadian oscillation. Mice carrying a reporter gene of AVP transcription (AVP(ELuc)) were produced by knocking-in a cDNA of Emerald-luciferase (ELuc) in the translational initiation site. Homozygous mice did not survive beyond postnatal day 7. Using the heterozygous (AVP(ELuc/+)) mice, a bioluminescence reporter system was developed that enabled to monitor AVP transcription through AVP-ELuc measurement in real time for more than 10 cycles in the cultured brain slice. AVP(ELuc/+) mice showed circadian behaviour rhythms and light responsiveness indistinguishable from those of the wild-type. Robust circadian rhythms in AVP-ELuc were detected in the cultured SCN slice at a single cell as well as tissue levels. The circadian rhythm of the whole SCN slice was stable, with the peak at the mid-light phase of a light-dark cycle, while that of a single cell was more variable. By comparison, rhythmicity in the paraventricular nucleus and supraoptic nucleus in the hypothalamus was unstable and damped rapidly. Spatiotemporal profiles of AVP expression at the pixel level revealed significant circadian rhythms in the entire area of AVP-positive cells in the SCN, and at least two clusters that showed different circadian oscillations. Contour analysis of bioluminescence intensity in a cell-like region demonstrated the radiation area was almost identical to the cell size. This newly developed reporter system for AVP gene expression is a useful tool for the study of circadian rhythms. PMID:26342201

  2. MATURATION OF FIRING PATTERN IN CHICK VESTIBULAR NUCLEUS NEURONS

    PubMed Central

    SHAO, M.; HIRSCH, J. C.; PEUSNER, K. D.

    2007-01-01

    The principal cells of the chick tangential nucleus are vestibular nucleus neurons participating in the vestibuloocular and vestibulocollic reflexes. In birds and mammals, spontaneous and stimulus-evoked firing of action potentials is essential for vestibular nucleus neurons to generate mature vestibular reflex activity. The emergence of spike-firing pattern and the underlying ion channels were studied in morphologically-identified principal cells using whole-cell patch-clamp recordings from brain slices of late-term embryos (embryonic day 16) and hatchling chickens (hatching day 1 and hatching day 5). Spontaneous spike activity emerged around the perinatal period, since at embryonic day 16 none of the principal cells generated spontaneous action potentials. However, at hatching day 1, 50% of the cells fired spontaneously (range, 3 to 32 spikes/s), which depended on synaptic transmission in most cells. By hatching day 5, 80% of the principal cells could fire action potentials spontaneously (range, 5 to 80 spikes/s), and this activity was independent of synaptic transmission and showed faster kinetics than at hatching day 1. Repetitive firing in response to depolarizing pulses appeared in the principal cells starting around embryonic day 16, when < 20% of the neurons fired repetitively. However, almost 90% of the principal cells exhibited repetitive firing on depolarization at hatching day 1, and 100% by hatching day 5. From embryonic day 16 to hatching day 5, the gain for evoked spike firing increased almost 10-fold. At hatching day 5, a persistent sodium channel was essential for the generation of spontaneous spike activity, while a small conductance, calcium-dependent potassium current modulated both the spontaneous and evoked spike firing activity. Altogether, these in vitro studies showed that during the perinatal period, the principal cells switched from displaying no spontaneous spike activity at resting membrane potential and generating one spike on

  3. Enhancement of forward suppression begins in the ventral cochlear nucleus.

    PubMed

    Ingham, Neil J; Itatani, Naoya; Bleeck, Stefan; Winter, Ian M

    2016-05-15

    A neuron׳s response to a sound can be suppressed by the presentation of a preceding sound. It has been suggested that this suppression is a direct correlate of the psychophysical phenomenon of forward masking, however, forward suppression, as measured in the responses of the auditory nerve, was insufficient to account for behavioural performance. In contrast the neural suppression seen in the inferior colliculus and auditory cortex was much closer to psychophysical performance. In anaesthetised guinea-pigs, using a physiological two-interval forced-choice threshold tracking algorithm to estimate suppressed (masked) thresholds, we examine whether the enhancement of suppression can occur at an earlier stage of the auditory pathway, the ventral cochlear nucleus (VCN). We also compare these responses with the responses from the central nucleus of the inferior colliculus (ICc) using the same preparation. In both nuclei, onset-type neurons showed the greatest amounts of suppression (16.9-33.5dB) and, in the VCN, these recovered with the fastest time constants (14.1-19.9ms). Neurons with sustained discharge demonstrated reduced masking (8.9-12.1dB) and recovery time constants of 27.2-55.6ms. In the VCN the decrease in growth of suppression with increasing suppressor level was largest for chopper units and smallest for onset-type units. The threshold elevations recorded for most unit types are insufficient to account for the magnitude of forward masking as measured behaviourally, however, onset responders, in both the cochlear nucleus and inferior colliculus demonstrate a wide dynamic range of suppression, similar to that observed in human psychophysics. PMID:26944300

  4. Boundary-precise segmentation of nucleus and plasma of leukocytes

    NASA Astrophysics Data System (ADS)

    Zerfaß, Thorsten; Rehn, Thomas; Wittenberg, Thomas

    2008-03-01

    The exact segmentation of nucleus and plasma of a white blood cell (leukocyte) is the basis for the creation of an automatic, image based differential white blood cell count(WBC). In this contribution we present an approach for the according segmentation of leukocytes. For a valid classification of the different cell classes, a precise segmentation is essential. Especially concerning immature cells, which can be distinguished from their mature counterparts only by small differences in some features, a segmentation of nucleus and plasma has to be as precise as possible, to extract those differences. Also the problems with adjacent erythrocyte cells and the usage of a LED illumination are considered. The presented approach can be separated into several steps. After preprocessing by a Kuwahara-filter, the cell is localized by a simple thresholding operation, afterwards a fast-marching method for the localization of a rough cell boundary is defined. To retrieve the cell area a shortest-path-algorithm is applied next. The cell boundary found by the fast-marching approach is finally enhanced by a post-processing step. The concluding segmentation of the cell nucleus is done by a threshold operation. An evaluation of the presented method was done on a representative sample set of 80 images recorded with LED illumination and a 63-fold magnification dry objective. The automatically segmented cell images are compared to a manual segmentation of the same dataset using the Dice-coefficient as well as Hausdorff-distance. The results show that our approach is able to handle the different cell classes and that it improves the segmentation quality significantly.

  5. Tractography patterns of subthalamic nucleus deep brain stimulation.

    PubMed

    Vanegas-Arroyave, Nora; Lauro, Peter M; Huang, Ling; Hallett, Mark; Horovitz, Silvina G; Zaghloul, Kareem A; Lungu, Codrin

    2016-04-01

    Deep brain stimulation therapy is an effective symptomatic treatment for Parkinson's disease, yet the precise mechanisms responsible for its therapeutic effects remain unclear. Although the targets of deep brain stimulation are grey matter structures, axonal modulation is known to play an important role in deep brain stimulation's therapeutic mechanism. Several white matter structures in proximity to the subthalamic nucleus have been implicated in the clinical benefits of deep brain stimulation for Parkinson's disease. We assessed the connectivity patterns that characterize clinically beneficial electrodes in Parkinson's disease patients, after deep brain stimulation of the subthalamic nucleus. We evaluated 22 patients with Parkinson's disease (11 females, age 57 ± 9.1 years, disease duration 13.3 ± 6.3 years) who received bilateral deep brain stimulation of the subthalamic nucleus at the National Institutes of Health. During an initial electrode screening session, one month after deep brain stimulation implantation, the clinical benefits of each contact were determined. The electrode was localized by coregistering preoperative magnetic resonance imaging and postoperative computer tomography images and the volume of tissue activated was estimated from stimulation voltage and impedance. Brain connectivity for the volume of tissue activated of deep brain stimulation contacts was assessed using probabilistic tractography with diffusion-tensor data. Areas most frequently connected to clinically effective contacts included the thalamus, substantia nigra, brainstem and superior frontal gyrus. A series of discriminant analyses demonstrated that the strength of connectivity to the superior frontal gyrus and the thalamus were positively associated with clinical effectiveness. The connectivity patterns observed in our study suggest that the modulation of white matter tracts directed to the superior frontal gyrus and the thalamus is associated with favourable clinical

  6. Active galactic nucleus feedback in clusters of galaxies

    PubMed Central

    Blanton, Elizabeth L.; Clarke, T. E.; Sarazin, Craig L.; Randall, Scott W.; McNamara, Brian R.

    2010-01-01

    Observations made during the last ten years with the Chandra X-ray Observatory have shed much light on the cooling gas in the centers of clusters of galaxies and the role of active galactic nucleus (AGN) heating. Cooling of the hot intracluster medium in cluster centers can feed the supermassive black holes found in the nuclei of the dominant cluster galaxies leading to AGN outbursts which can reheat the gas, suppressing cooling and large amounts of star formation. AGN heating can come in the form of shocks, buoyantly rising bubbles that have been inflated by radio lobes, and the dissipation of sound waves. PMID:20351250

  7. Single-Nucleus Polycrystallization in Thin Film Epitaxial Growth

    SciTech Connect

    Sadowski, J. T.; Nishikata, S.; Al-Mahboob, A.; Fujikawa, Y.; Nakajima, K.; Sakurai, T.; Sazaki, G.; Tromp, R. M.

    2007-01-26

    We have observed, by use of low-energy electron microscopy, the first direct evidence of self-driven polycrystallization evolved from a single nucleus in the case of epitaxial pentacene growth on the Si(111)-H terminated surface. In this Letter we demonstrate that such polycrystallization can develop in anisotropic systems (in terms of crystal structure and/or the intermolecular interactions) when kinetic growth conditions force the alignment of the intrinsic preferential growth directions along the density gradient of diffusing molecules. This finding gives new insight into the crystallization of complex molecular systems, elucidating the importance of nanoscale control of the growth conditions.

  8. Movement and localization of RNA in the cell nucleus.

    PubMed

    Pederson, T

    1999-12-01

    The movement of various RNAs from their sites of chromosomal synthesis to their functional locations in the cell is an important step in eukaryotic gene readout, though one less well understood than the transcription, RNA processing, and various functions of RNA. The segregation of the many classes of RNA out into to their appropriate sites in the cell is, from a physical chemical point of view, a remarkable phenomenon. This paper summarizes investigations my colleagues and I have undertaken over the past 7 years to describe the intracellular traffic and localization of RNA in living cells. One approach we have developed is to glass-needle microinject approximately 0.01 pl of fluorescent RNA solutions into the nucleus or cytoplasm of cultured mammalian cells. This 'fluorescent RNA cytochemistry' approach has resolved intranuclear sites ('speCkles') for which premessenger RNAs (pre-mRNA) have high affinity and has revealed very rapid movements of certain other RNAs from their nucleoplasmic injection sites to the nucleoli. One of these rapidly trafficking nucleolar RNAs is the signal recognition particle (SRP) RNA, and further results indicate that the nucleolus is a site of SRP RNA processing or ribonucleoprotein assembly prior to export to the cytoplasm. In these fluorescent RNA microinjection studies, we have also used mutant RNA molecules to identify specific nucleotide sequences that function as targeting elements for the localization of RNAs at their respective intranuclear sites. In a second approach, we have used fluorescent correlation spectroscopy (FCS), a classical biophysical method for measuring molecular motion in vitro, coupled with confocal fluorescence microscopy to measure the movement of poly(A) RNA in the nucleus, with the interesting finding that these RNAs appear to move about inside the nucleus at rates comparable to diffusion in aqueous solution. Parallel experiments using the method of fluorescence recovery after photobleaching (FRAP

  9. Double blocking in the superdeformed sup 192 Tl nucleus

    SciTech Connect

    Liang, Y.; Carpenter, M.P.; Janssens, R.V.F.; Ahmad, I.; Henry, R.; Khoo, T.L.; Lauritsen, T. ); Soramel, F. Padua Univ. ); Pilotte, S. ); Lewis, J.M.; Riedinger, L.L.; Yu, C.H. ); Garg, U.; Reviol, W. ); Be

    1992-01-01

    Six superdeformed bands have been found in the nucleus {sup 192}Tl. For two of the bands, the dynamic moment of inertia J{sup (2)} is found to be constant with the rotational frequency {Dirac h}. This result can be understood in terms of Pauli blocking of quasiparticle alignments in intruder orbitals, and represents the first experimental evidence that the alignment of these intruders is responsible for the smooth rise in J{sup (2)} seen in other superdeformed nuclei of this mass region.

  10. Double blocking in the superdeformed {sup 192}Tl nucleus

    SciTech Connect

    Liang, Y.; Carpenter, M.P.; Janssens, R.V.F.; Ahmad, I.; Henry, R.; Khoo, T.L.; Lauritsen, T.; Soramel, F. |; Pilotte, S.; Lewis, J.M.; Riedinger, L.L.; Yu, C.H.; Garg, U.; Reviol, W.; Bearden, I.G.

    1992-08-01

    Six superdeformed bands have been found in the nucleus {sup 192}Tl. For two of the bands, the dynamic moment of inertia J{sup (2)} is found to be constant with the rotational frequency {Dirac_h}. This result can be understood in terms of Pauli blocking of quasiparticle alignments in intruder orbitals, and represents the first experimental evidence that the alignment of these intruders is responsible for the smooth rise in J{sup (2)} seen in other superdeformed nuclei of this mass region.

  11. Magnetic Moment of Proton Drip-Line Nucleus (9)C

    NASA Technical Reports Server (NTRS)

    Matsuta, K.; Fukuda, M.; Tanigaki, M.; Minamisono, T.; Nojiri, Y.; Mihara, M.; Onishi, T.; Yamaguchi, T.; Harada, A.; Sasaki, M.

    1994-01-01

    The magnetic moment of the proton drip-line nucleus C-9(I(sup (pi)) = 3/2, T(sub 1/2) = 126 ms) has been measured for the first time, using the beta-NMR detection technique with polarized radioactive beams. The measure value for the magnetic moment is 1mu(C-9)! = 1.3914 +/- 0.0005 (mu)N. The deduced spin expectation value of 1.44 is unusually larger than any other ones of even-odd nuclei.

  12. R-loops highlight the nucleus in ALS.

    PubMed

    Salvi, Jayesh S; Mekhail, Karim

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a severely debilitating neurodegenerative disease linked to mutations in various genes implicated in cytoplasmic RNA metabolism. Recent studies from genetic models have also helped reveal connections between various ALS-linked factors and RNA-DNA hybrid (R-loop) regulation. Here, we examine how such hybrid-regulatory processes are pointing to a key role for the nucleus in ALS. We also present a potential molecular mechanism in which hybrids may represent at least one of the long sought after missing links between different ALS genes. Our opinion is that RNA-DNA hybrids will play a key role in deciphering ALS and other human diseases.

  13. Antinucleus-Nucleus Cross Sections Implemented in Geant4

    SciTech Connect

    Uzhinsky, V.; Apostolakis, J.; Galoyan, A.; Folger, G.; Grichine, V.M.; Ivanchenko, V.N.; Wright, D.H.; /SLAC

    2012-04-26

    Cross sections of antinucleus ({bar p}, {bar d}, {bar t}, {sup 3}{ovr He}, {sup 4}{ovr He}) interactions with nuclei in the energy range 100 MeV/c to 1000 GeV/c per antinucleon are calculated in the Glauber approximation which provides good description of all known {bar p}Across sections. The results were obtained using a new parameterization of the total and elastic {bar p}p cross sections. Simple parameterizations of the antinucleus-nucleus cross sections are proposed for use in estimating the efficiency of antinucleus detection and tracking in cosmic rays and accelerator experiments. These parameterizations are implemented in the Geant4 toolkit.

  14. Lepton event rates in neutrino-nucleus DIS

    SciTech Connect

    Haider, H.; Athar, M. Sajjad; Simo, I. Ruiz; Vicente Vacas, M. J.

    2011-10-06

    In this work we have studied the nuclear effect in F{sub 2}{sup A}(x) and F{sub 3}{sup A}(x) weak structure functions and calculated {nu}-nucleus cross section using them by taking into account Fermi motion, binding energy, pion and rho meson cloud contributions and shadowing and anti-shadowing effects. The numerical calculations have been performed in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. The results have been compared with the experimental results of NuTeV and CDHSW collaborations.

  15. Workshop on Analysis of Returned Comet Nucleus Samples

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This volume contains abstracts that were accepted by the Program Committee for presentation at the workshop on the analysis of returned comet nucleus samples held in Milpitas, California, January 16 to 18, 1989. The abstracts deal with the nature of cometary ices, cryogenic handling and sampling equipment, origin and composition of samples, and spectroscopic, thermal and chemical processing methods of cometary nuclei. Laboratory simulation experimental results on dust samples are reported. Some results obtained from Halley's comet are also included. Microanalytic techniques for examining trace elements of cometary particles, synchrotron x ray fluorescence and instrument neutron activation analysis (INAA), are presented.

  16. Spatial regulation and organization of DNA replication within the nucleus.

    PubMed

    Natsume, Toyoaki; Tanaka, Tomoyuki U

    2010-01-01

    Duplication of chromosomal DNA is a temporally and spatially regulated process. The timing of DNA replication initiation at various origins is highly coordinated; some origins fire early and others late during S phase. Moreover, inside the nuclei, the bulk of DNA replication is physically organized in replication factories, consisting of DNA polymerases and other replication proteins. In this review article, we discuss how DNA replication is organized and regulated spatially within the nucleus and how this spatial organization is linked to temporal regulation. We focus on DNA replication in budding yeast and fission yeast and, where applicable, compare yeast DNA replication with that in bacteria and metazoans.

  17. Arachnophobia alleviated by subthalamic nucleus stimulation for Parkinson's disease.

    PubMed

    Allert, Niels; Gippert, Sabrina M; Sajonz, Bastian E A; Nelles, Christoph; Bewernick, Bettina; Schlaepfer, Thomas E; Coenen, Volker A

    2016-06-01

    We report on a Parkinson patient with motor fluctuations and dyskinesias in whom deep brain stimulation (DBS) of the subthalamic nucleus (STN) not only improved motor symptoms but also pre-existing arachnophobia. Arachnophobia had been unchanged by the course of Parkinson's disease but rapidly improved with STN-DBS. Both, motor effects and the improvement of arachnophobia were stable during 2 years follow-up. To our knowledge this is the first report on STN stimulation effects on a specific phobia. PMID:27198699

  18. Nucleus lentiformis--a new model for psychiatry?

    PubMed

    Sperling, W; Müller, H

    2011-05-01

    In a regions of interest analysis (ROI) of the most frequent psychiatric disorders (schizophrenia, depression, anxiety, addiction), we found the nucleus lentiformis to be the topographical brain region most frequently cited in connection with these disorders in a regions of interest survey of publications between 1990-2010. This structure, which controls particularly motorics, appears to have a much greater importance than has thus far been assumed in the control and modulation of psychiatric disorders. The question of the extent to which this region has its own control function with respect to the disorders should be addressed in further studies along with clarification of possible influence factors on the activity.

  19. Mineralogy and Petrology of COMET WILD2 Nucleus Samples

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Bland, Phil; Bradley, John; Brearley, Adrian; Brennan, Sean; Bridges, John; Brownlee, Donald; Butterworth, Anna; Dai, Zurong; Ebel, Denton

    2006-01-01

    The sample return capsule of the Stardust spacecraft will be recovered in northern Utah on January 15, 2006, and under nominal conditions it will be delivered to the new Stardust Curation Laboratory at the Johnson Space Center two days later. Within the first week we plan to begin the harvesting of aerogel cells, and the comet nucleus samples they contain for detailed analysis. By the time of the LPSC meeting we will have been analyzing selected removed grains for more than one month. This presentation will present the first results from the mineralogical and petrological analyses that will have been performed.

  20. Search for exotic cluster configurations in 14C nucleus

    NASA Astrophysics Data System (ADS)

    Korotkova, L. Yu; Chernyshev, B. A.; Gurov, Yu B.; Karpuhin, V. S.; Lapushkin, S. V.; Pritula, R. V.; Schurenkova, T. D.

    2016-02-01

    The analysis of 2-dimentional Dalitz’ diagram, measured in 14C(π-, pd)X reaction, allowed to distinguish the pion absorption by p intranuclear cluster and to obtain an indication on the existence of 3p + 11Li configuration in 14C nucleus. Highly excited states of 12,13Be isotopes were found with the energy of Ex ≈ 30 MeV for the first time. It was shown that these states decay as follows 12Be*→p + 11Li and 13Be*→d + 11Li.

  1. Functional roles of HIV-1 Tat protein in the nucleus.

    PubMed

    Musinova, Yana R; Sheval, Eugene V; Dib, Carla; Germini, Diego; Vassetzky, Yegor S

    2016-02-01

    Human immunodeficiency virus-1 (HIV-1) Tat protein is one of the most important regulatory proteins for viral gene expression in the host cell and can modulate different cellular processes. In addition, Tat is secreted by the infected cell and can be internalized by neighboring cells; therefore, it affects both infected and uninfected cells. Tat can modulate cellular processes by interacting with different cellular structures and signaling pathways. In the nucleus, Tat might be localized either in the nucleoplasm or the nucleolus depending on its concentration. Here we review the distinct functions of Tat in the nucleoplasm and the nucleolus in connection with viral infection and HIV-induced oncogenesis. PMID:26507246

  2. Electrical stimulation of the salivatory nucleus in the rat.

    PubMed Central

    Donaldson, J; Mitchell, J; Templeton, D

    1984-01-01

    Unilateral electrical stimulation of the salivatory nucleus evoked a secretion from the ipsilateral parotid gland which was well maintained. Flow rate was not affected by sympathetic decentralization or by adrenoceptor antagonists but was abolished by atropine. Protein secretion was reduced by beta-adrenoceptor antagonists but not by sympathetic decentralization or adrenalectomy. In support of previous histochemical findings it is concluded that the cells of the reticular formation are the origin of the preganglionic parasympathetic fibres to the salivary glands but that a beta-adrenoceptor mechanism as yet unidentified is also involved in the protein secretion. PMID:6520785

  3. Thalamic reticular nucleus in Caiman crocodilus: Relationship with the dorsal thalamus.

    PubMed

    Pritz, M B

    2016-05-13

    The thalamic reticular nucleus was investigated in one group of crocodilians, Caiman crocodilus. This neuronal aggregate is composed of two parts: a compact portion and a diffuse region made up of scattered cells within the forebrain bundles. In Caiman, both the lateral and medial forebrain bundles project to the telencephalon and the thalamic reticular nucleus is associated with each fiber tract. In the lateral forebrain bundle, the compact area is termed the nucleus of the dorsal peduncle (dorsal peduncular nucleus) while the diffuse part is called the perireticular area. In the medial forebrain bundle, the interstitial nucleus comprises one part of the compact area while another region without a specific neuronal label is also present. Similar to the perireticular cells of the lateral forebrain bundle, scattered cells are also present in the medial forebrain bundle. Morphological features of the thalamic reticular nucleus are revealed with stains for the following: fibers; cells; succinic acid dehydrogenase; and acetylcholinesterase. Regardless of which dorsal thalamic nucleus was injected, a localized region of the thalamic reticular nucleus contained retrogradely labeled cells and anterogradely labeled axons and terminals. This grouping was termed clusters and was felt to represent the densest interconnection between the dorsal thalamus and the reticular nucleus. Using clusters as an index of interconnections, the reticular nucleus was divided into sectors, each of which was associated with a specific dorsal thalamic nucleus. An organization similar to that found in Caiman is present in other sauropsids as well as in mammals. These data suggest that a thalamic reticular nucleus is present in all amniotes and has morphological properties similar to those described in this analysis. Lastly, a hypothesis is presented to explain how the external shape of the reticular nucleus in Caiman might be transformed into the homologous area in a representative bird and

  4. The development of the Nucleus Freedom Cochlear implant system.

    PubMed

    Patrick, James F; Busby, Peter A; Gibson, Peter J

    2006-12-01

    Cochlear Limited (Cochlear) released the fourth-generation cochlear implant system, Nucleus Freedom, in 2005. Freedom is based on 25 years of experience in cochlear implant research and development and incorporates advances in medicine, implantable materials, electronic technology, and sound coding. This article presents the development of Cochlear's implant systems, with an overview of the first 3 generations, and details of the Freedom system: the CI24RE receiver-stimulator, the Contour Advance electrode, the modular Freedom processor, the available speech coding strategies, the input processing options of Smart Sound to improve the signal before coding as electrical signals, and the programming software. Preliminary results from multicenter studies with the Freedom system are reported, demonstrating better levels of performance compared with the previous systems. The final section presents the most recent implant reliability data, with the early findings at 18 months showing improved reliability of the Freedom implant compared with the earlier Nucleus 3 System. Also reported are some of the findings of Cochlear's collaborative research programs to improve recipient outcomes. Included are studies showing the benefits from bilateral implants, electroacoustic stimulation using an ipsilateral and/or contralateral hearing aid, advanced speech coding, and streamlined speech processor programming.

  5. Evolution of the red nucleus and rubrospinal tract.

    PubMed

    ten Donkelaar, H J

    1988-01-01

    A red nucleus, defined by its relative position in the tegmentum mesencephali, its contralateral rubrospinal or rubrobulbar projections and by crossed cerebellar afferents, is found in terrestrial vertebrates and certain rays. A crossed rubrospinal tract occurs in anurans, limbed urodeles and reptiles, birds and mammals, but is apparently absent in boid snakes, caecilians and sharks. A distinct rubrospinal tract is found in certain rays which use their enlarged pectoral fins for locomotion. A crossed tegmentospinal tract, possibly a rubrospinal tract, is found in lungfishes. Although evidence was presented for a rubrospinal tract in more advanced snakes, the available experimental data in lower vertebrates suggest that the presence of a rubrospinal tract is related to the presence of limbs or limb-like structures. In the connectivity of the red nucleus in terrestrial vertebrates, 'levels' of complexity can be distinguished, paralleled by the development of the cerebellum. These 'grades of organization' are probably related to the type of motor performance the particular terrestrial vertebrates are capable of.

  6. A thalamic input to the nucleus accumbens mediates opiate dependence

    PubMed Central

    Zhu, Yingjie; Wienecke, Carl F.R.; Nachtrab, Gregory; Chen, Xiaoke

    2016-01-01

    Chronic opiate use induces opiate dependence, which is characterized by extremely unpleasant physical and emotional feelings after drug use is terminated. Both rewarding effects of drug and the desire to avoid withdrawal symptoms motivate continued drug use1-3, and the nucleus accumbens (NAc) is important for orchestrating both processes4,5. While multiple inputs to the NAc regulate reward6-9, little is known about the NAc circuitry underlying withdrawal. Here we identify the paraventricular nucleus of the thalamus (PVT) as a prominent input to the NAc mediating the expression of opiate withdrawal induced physical signs and aversive memory. Activity in the PVT to NAc pathway is necessary and sufficient to mediate behavioral aversion. Selectively silencing this pathway abolishes aversive symptoms in two different mouse models of opiate withdrawal. Chronic morphine exposure selectively potentiates excitatory transmission between the PVT and D2-receptor-expressing medium spiny neurons (D2-MSNs) via synaptic insertion of GluA2-lacking AMPA receptors. Notably, in vivo optogenetic depotentiation restores normal transmission at PVT→D2-MSNs synapses and robustly suppresses morphine withdrawal symptoms. These results link morphine-evoked pathway- and cell type-specific plasticity in the PVT→NAc circuit to opiate dependence, and suggest that reprogramming this circuit holds promise for treating opiate addiction. PMID:26840481

  7. Lesions of nucleus tractus solitarii globally impair cerebrovascular autoregulation

    SciTech Connect

    Ishitsuka, T.; Iadecola, C.; Underwood, M.D.; Reis, D.J.

    1986-08-01

    The authors studied the effects of acute bilateral electrolytic lesions of the nucleus tractus solitarii (NTS) on regional cerebral blood flow (rCBF) and its autoregulation in rats anesthetized, paralyzed, and artificially ventilated. rCBF or regional cerebral glucose utilization (rCGU) was measured 30 min after NTS lesions, by the UC-iodoantipyrine technique or 2-deoxyglucose method, respectively. Cerebrovascular autoregulation was assessed in groups of 4-5 rats at three levels of arterial pressure (AP):90, 125, and 140 mmHg. AP was lowered by hemorrhage or elevated by intravenous infusion of phenylephrine. NTS lesions did not alter rCBF at 125 mmHg but resulted in loss of autoregulation. In contrast, lesions of the cuneate nucleus or transection of the baroreceptor afferents did not alter autoregulation. NTS lesions did not affect the reactivity of the cerebrovascular bed to hypercarbia or hypocarbia nor the rCGU in any brain regions. They conclude that lesions of the NTS impair cerebrovascular autoregulation. The effect is not due to changes in metabolism, nonspecific effects of the lesions, vasoparalysis, or interruption of the baroreceptor reflex arch. Neural pathways originating in or passing through the NTS can regulate the cerebrovascular autoregulation of the entire brain.

  8. Ancient class of translocated oomycete effectors targets the host nucleus.

    PubMed

    Schornack, Sebastian; van Damme, Mireille; Bozkurt, Tolga O; Cano, Liliana M; Smoker, Matthew; Thines, Marco; Gaulin, Elodie; Kamoun, Sophien; Huitema, Edgar

    2010-10-01

    Pathogens use specialized secretion systems and targeting signals to translocate effector proteins inside host cells, a process that is essential for promoting disease and parasitism. However, the amino acid sequences that determine host delivery of eukaryotic pathogen effectors remain mostly unknown. The Crinkler (CRN) proteins of oomycete plant pathogens, such as the Irish potato famine organism Phytophthora infestans, are modular proteins with predicted secretion signals and conserved N-terminal sequence motifs. Here, we provide direct evidence that CRN N termini mediate protein transport into plant cells. CRN host translocation requires a conserved motif that is present in all examined plant pathogenic oomycetes, including the phylogenetically divergent species Aphanomyces euteiches that does not form haustoria, specialized infection structures that have been implicated previously in delivery of effectors. Several distinct CRN C termini localized to plant nuclei and, in the case of CRN8, required nuclear accumulation to induce plant cell death. These results reveal a large family of ubiquitous oomycete effector proteins that target the host nucleus. Oomycetes appear to have acquired the ability to translocate effector proteins inside plant cells relatively early in their evolution and before the emergence of haustoria. Finally, this work further implicates the host nucleus as an important cellular compartment where the fate of plant-microbe interactions is determined.

  9. Automatic leukocyte nucleus segmentation by intuitionistic fuzzy divergence based thresholding.

    PubMed

    Jati, Arindam; Singh, Garima; Mukherjee, Rashmi; Ghosh, Madhumala; Konar, Amit; Chakraborty, Chandan; Nagar, Atulya K

    2014-03-01

    The paper proposes a robust approach to automatic segmentation of leukocyte's nucleus from microscopic blood smear images under normal as well as noisy environment by employing a new exponential intuitionistic fuzzy divergence based thresholding technique. The algorithm minimizes the divergence between the actual image and the ideally thresholded image to search for the final threshold. A new divergence formula based on exponential intuitionistic fuzzy entropy has been proposed. Further, to increase its noise handling capacity, a neighborhood-based membership function for the image pixels has been designed. The proposed scheme has been applied on 110 normal and 54 leukemia (chronic myelogenous leukemia) affected blood samples. The nucleus segmentation results have been validated by three expert hematologists. The algorithm achieves an average segmentation accuracy of 98.52% in noise-free environment. It beats the competitor algorithms in terms of several other metrics. The proposed scheme with neighborhood based membership function outperforms the competitor algorithms in terms of segmentation accuracy under noisy environment. It achieves 93.90% and 94.93% accuracies for Speckle and Gaussian noises, respectively. The average area under the ROC curves comes out to be 0.9514 in noisy conditions, which proves the robustness of the proposed algorithm.

  10. Adaptive local thresholding for robust nucleus segmentation utilizing shape priors

    NASA Astrophysics Data System (ADS)

    Wang, Xiuzhong; Srinivas, Chukka

    2016-03-01

    This paper describes a novel local thresholding method for foreground detection. First, a Canny edge detection method is used for initial edge detection. Then, tensor voting is applied on the initial edge pixels, using a nonsymmetric tensor field tailored to encode prior information about nucleus size, shape, and intensity spatial distribution. Tensor analysis is then performed to generate the saliency image and, based on that, the refined edge. Next, the image domain is divided into blocks. In each block, at least one foreground and one background pixel are sampled for each refined edge pixel. The saliency weighted foreground histogram and background histogram are then created. These two histograms are used to calculate a threshold by minimizing the background and foreground pixel classification error. The block-wise thresholds are then used to generate the threshold for each pixel via interpolation. Finally, the foreground is obtained by comparing the original image with the threshold image. The effective use of prior information, combined with robust techniques, results in far more reliable foreground detection, which leads to robust nucleus segmentation.

  11. Hubble Imaging of the Nucleus of Comet ISON

    NASA Astrophysics Data System (ADS)

    Lamy, Philippe

    2013-10-01

    Comet C/2012 S1 {ISON} is both a new "nearly isotropic" and a sungrazing comet with anoutstanding apparition in cycle 21, passing within 0.42 AU of the Earth.We propose a 12-orbit Hubble postperihelion investigation of this comet that will provide a detailed view of its nucleus originating from the Oort cloud and of the possible consequences of its very close approach to the Sun at a perihelion distance of 0.012471 AU such as fragmentation.We will determine the size, shape, rotational period, and color {UBVRI} ofthe nucleus of C/2012 S1 or of its fragment should disruption occurs. This passage of a new "nearly isotropic" comet very close tothe Earth offers a rare opportunity to investigate this population ofobjects, and we expect many other observatories to attempt detecting itsnucleus in the mid-infrared, millimetric and centimetric domains.Combining the Hubble results with those from other observatories shouldyield a comprehensive picture of this NIC that can be compared to thedetailed data collected on ecliptic comets {ECs} during the past 3decades. The differences and similarities between NICs and ECs shouldyield valuable insights into the origin and evolution of comets.

  12. Extinction of a classically conditioned response: red nucleus and interpositus.

    PubMed

    Robleto, Karla; Thompson, Richard F

    2008-03-01

    It is well established that the cerebellum and its associated circuitry are essential for classical conditioning of the eyeblink response and other discrete motor responses (e.g., limb flexion, head turn, etc.) learned with an aversive unconditioned stimulus. However, brain mechanisms underlying extinction of these responses are still relatively unclear. Behavioral studies have demonstrated extinction to be an active learning process distinct from acquisition. Accordingly, this current understanding of extinction has guided neural studies that have tried to identify possible brain structures that could support this new learning. However, whether extinction engages the same brain sites necessary for acquisition is not yet clear. This poses an overriding problem for understanding brain mechanisms necessary for extinction because such analysis cannot be done without first identifying brain sites and pathways involved in this phenomenon. Equally elusive is the validity of a behavioral theory of extinction that can account for the properties of extinction. In this study, we looked at the involvement of the interpositus and the red nucleus in extinction. Results show that, although inactivation of both nuclei blocks response expression, only inactivation of the interpositus has a detrimental effect on extinction. Moreover, this detrimental effect was completely removed when inactivation of the interpositus was paired with electrical stimulation of the red nucleus. These findings speak to the important role of cerebellar structures in the extinction of discrete motor responses and provide important insight as to the validity of a particular theory of extinction.

  13. Tools for visualization of phosphoinositides in the cell nucleus.

    PubMed

    Kalasova, Ilona; Fáberová, Veronika; Kalendová, Alžběta; Yildirim, Sukriye; Uličná, Lívia; Venit, Tomáš; Hozák, Pavel

    2016-04-01

    Phosphoinositides (PIs) are glycerol-based phospholipids containing hydrophilic inositol ring. The inositol ring is mono-, bis-, or tris-phosphorylated yielding seven PIs members. Ample evidence shows that PIs localize both to the cytoplasm and to the nucleus. However, tools for direct visualization of nuclear PIs are limited and many studies thus employ indirect approaches, such as staining of their metabolic enzymes. Since localization and mobility of PIs differ from their metabolic enzymes, these approaches may result in incomplete data. In this paper, we tested commercially available PIs antibodies by light microscopy on fixed cells, tested their specificity using protein-lipid overlay assay and blocking assay, and compared their staining patterns. Additionally, we prepared recombinant PIs-binding domains and tested them on both fixed and live cells by light microscopy. The results provide a useful overview of usability of the tools tested and stress that the selection of adequate tools is critical. Knowing the localization of individual PIs in various functional compartments should enable us to better understand the roles of PIs in the cell nucleus.

  14. The contemporary nucleus: a trip down memory lane.

    PubMed

    Osorio, Daniel S; Gomes, Edgar R

    2013-09-01

    The nucleus is one of the hallmarks of eukaryotic cells. The history of its discovery and characterisation is intimately entangled with that of cell biology as a discipline. Here, we provide a broad historical perspective of the nucleus, from its initial descriptions until the present. We describe the key events that led to the formulation of the chromosomal theory, the discovery of the nuclear pore complex, nucleo-cytoplasmic transport and the structure of chromatin. We also focus on the rising importance of the nuclear periphery as a key subject in nuclear research, with the characterisation of the multiple roles of nuclear lamina and the proteins involved in connecting the nuclear envelope and the cytoskeleton. Over the last decades, critical technical advancements from electron microscopy to protein structural characterisation have allowed us to gain in-depth knowledge of nuclear substructure and components, from its core to the envelope. This knowledge has set the stage for a rising challenge: understanding specialised nuclear configurations and their role in different tissues, developmental stages and disease.

  15. Evaluation of novel injectable hydrogels for nucleus pulposus replacement.

    PubMed

    Vernengo, J; Fussell, G W; Smith, N G; Lowman, A M

    2008-01-01

    Branched copolymers composed of poly(N-isopropylacrylamide) (PNIPAAm) and poly(ethylene glycol) (PEG) are being investigated as an in situ forming replacement for the nucleus pulposus of the intervertebral disc. A family of copolymers was synthesized by varying the molecular weight of the PEG blocks and molar ratio of NIPAAm monomer units to PEG branches. Gel swelling, dissolution, and compressive mechanical properties were characterized over 90 days and stress relaxation behavior over 30 days immersion in vitro. It was found that the NIPAAm to PEG molar ratio did not affect the equilibrium swelling and compressive mechanical properties. However, gel elasticity exhibited a dependency on both the PEG block molecular weight and content. The equilibrium gel water content increased and compressive modulus decreased with increasing PEG block size. While all of the branched copolymers showed significant increases in stress relaxation time constant compared to the homopolymer (p < 0.05), the high PEG content PNIPAAm-PEG (4600 and 8000 g/mol) exhibited the maximum elasticity. Because of its high water content, requisite stiffness and high elastic response, PNIPAAm-PEG (4600 g/mol) will be further evaluated as a candidate material for nucleus pulposus replacement.

  16. Level structures in odd-odd deformed nucleus 184Ta

    NASA Astrophysics Data System (ADS)

    Gowrishankar, R.; Sood, P. C.

    2016-02-01

    A detailed low-energy level scheme of the odd-odd n-rich nucleus 184 73Ta111 is constructed using the well tested Two-Quasiparticle Rotor Model (TQRM) for calculating the bandhead energies of physically admissible 2qp configurations with the inclusion of residual n-p interaction contribution. The presently available data on this level scheme from 184Hf decay are shown to be in agreement with these calculations. Our analysis concludes that 184Hf ( Q_{β}=1340(30) keV) decay admits of 7 additional (to the 3 presently reported) β-branches to 184Ta with J = 0 or 1 and 8 more physically admissible weak ( 1fu β-branches populating J^{π}=2- levels in 184Ta. Further, a close examination of our level scheme clearly indicates the existence of a low-lying ( Ex = 260(40) keV) high-spin ( J^{π}=10-) long-lived isomer in this nucleus.

  17. Extinction of a classically conditioned response: red nucleus and interpositus.

    PubMed

    Robleto, Karla; Thompson, Richard F

    2008-03-01

    It is well established that the cerebellum and its associated circuitry are essential for classical conditioning of the eyeblink response and other discrete motor responses (e.g., limb flexion, head turn, etc.) learned with an aversive unconditioned stimulus. However, brain mechanisms underlying extinction of these responses are still relatively unclear. Behavioral studies have demonstrated extinction to be an active learning process distinct from acquisition. Accordingly, this current understanding of extinction has guided neural studies that have tried to identify possible brain structures that could support this new learning. However, whether extinction engages the same brain sites necessary for acquisition is not yet clear. This poses an overriding problem for understanding brain mechanisms necessary for extinction because such analysis cannot be done without first identifying brain sites and pathways involved in this phenomenon. Equally elusive is the validity of a behavioral theory of extinction that can account for the properties of extinction. In this study, we looked at the involvement of the interpositus and the red nucleus in extinction. Results show that, although inactivation of both nuclei blocks response expression, only inactivation of the interpositus has a detrimental effect on extinction. Moreover, this detrimental effect was completely removed when inactivation of the interpositus was paired with electrical stimulation of the red nucleus. These findings speak to the important role of cerebellar structures in the extinction of discrete motor responses and provide important insight as to the validity of a particular theory of extinction. PMID:18322108

  18. Order out of chaos in the hybrid plant nucleus.

    PubMed

    Jones, R N; Hegarty, M

    2009-01-01

    The plant nucleus is a highly ordered and dynamic structure, with a considerable level of variation between species in terms of genome size, genome organisation, chromosome territories and patterns associated with developmental changes. Diploids naturally represent the simplest state of affairs, but in the plant world more than 70% of species may have been involved in polyploidisation events at some stage during their evolution. Autopolyploids have multiple sets of chromosomes from a single species, and aside from the complexities of meiosis we may expect them to accommodate their polysomic state as well as their disomic relatives. Allopolyploids are at the other extreme, with multiple sets of chromosomes from 2 or more species, embedded in the cytoplasm of the maternal parent following hybridisation, and this presents the nucleus of nascent allopolyploids with certain zones of conflict. Nature has found ways to make the accommodation, and recent developments in molecular analysis have now opened a window for the experimenter to view the process of this adjustment, and to see how rapidly it takes place and what processes are involved. The nature of the resolution of nuclear conflicts in diploid hybrids and in allopolyploids is discussed.

  19. Cytoarchitectonic and quantitative Golgi study of the hedgehog supraoptic nucleus.

    PubMed Central

    Caminero, A A; Machín, C; Sanchez-Toscano, F

    1992-01-01

    A cytoarchitectural study was made of the supraoptic nucleus (SON) of the hedgehog with special attention to the quantitative comparison of its main neuronal types. The main purposes were (1) to relate the characteristics of this nucleus in the hedgehog (a primitive mammalian insectivorous brain) with those in the SONs of more evolutionarily advanced species; (2) to identify quantitatively the dendritic fields of the main neuronal types in the hedgehog SON and to study their synaptic connectivity. From a descriptive standpoint, 3 neuronal types were found with respect to the number of dendritic stems arising from the neuronal soma: bipolar neurons (48%), multipolar neurons (45.5%) and monopolar neurons (6.5%). Within the multipolar type 2 subtypes could be distinguished, taking into account the number of dendritic spines: (a) with few spines (93%) and (b) very spiny (7%). These results indicate that the hedgehog SON is similar to that in other species except for the very spiny neurons, the significance of which is discussed. In order to characterise the main types more satisfactorily (bipolar and multipolars with few spines) we undertook a quantitative Golgi study of their dendritic fields. Although the patterns of the dendritic field are similar in both neuronal types, the differences in the location of their connectivity can reflect functional changes and alterations in relation to the synaptic afferences. Images Fig. 2 Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 PMID:1452481

  20. Urocortin 3 elevates cytosolic calcium in nucleus ambiguus neurons.

    PubMed

    Brailoiu, G Cristina; Deliu, Elena; Tica, Andrei A; Chitravanshi, Vineet C; Brailoiu, Eugen

    2012-09-01

    Urocortin 3 (also known as stresscopin) is an endogenous ligand for the corticotropin-releasing factor receptor 2 (CRF(2)). Despite predominant G(s) coupling of CRF(2), promiscuous coupling with other G proteins has been also associated with the activation of this receptor. As urocortin 3 has been involved in central cardiovascular regulation at hypothalamic and medullary sites, we examined its cellular effects on cardiac vagal neurons of nucleus ambiguus, a key area for the autonomic control of heart rate. Urocortin 3 (1 nM-1000 nM) induced a concentration-dependent increase in cytosolic Ca(2+) concentration that was blocked by the CRF(2) antagonist K41498. In the case of two consecutive treatments with urocortin 3, the second urocortin 3-induced Ca(2+) response was reduced, indicating receptor desensitization. The effect of urocortin 3 was abolished by pre-treatment with pertussis toxin and by inhibition of phospolipase C with U-73122. Urocortin 3 activated Ca(2+) influx via voltage-gated P/Q-type channels as well as Ca(2+) release from endoplasmic reticulum. Urocortin 3 promoted Ca(2+) release via inositol 1,4,5 trisphosphate receptors, but not ryanodine receptors. Our results indicate a novel Ca(2+) -mobilizing effect of urocortin 3 in vagal pre-ganglionic neurons of nucleus ambiguus, providing a cellular mechanism for a previously reported role for this peptide in parasympathetic cardiac regulation.

  1. Evolution of the red nucleus and rubrospinal tract.

    PubMed

    ten Donkelaar, H J

    1988-01-01

    A red nucleus, defined by its relative position in the tegmentum mesencephali, its contralateral rubrospinal or rubrobulbar projections and by crossed cerebellar afferents, is found in terrestrial vertebrates and certain rays. A crossed rubrospinal tract occurs in anurans, limbed urodeles and reptiles, birds and mammals, but is apparently absent in boid snakes, caecilians and sharks. A distinct rubrospinal tract is found in certain rays which use their enlarged pectoral fins for locomotion. A crossed tegmentospinal tract, possibly a rubrospinal tract, is found in lungfishes. Although evidence was presented for a rubrospinal tract in more advanced snakes, the available experimental data in lower vertebrates suggest that the presence of a rubrospinal tract is related to the presence of limbs or limb-like structures. In the connectivity of the red nucleus in terrestrial vertebrates, 'levels' of complexity can be distinguished, paralleled by the development of the cerebellum. These 'grades of organization' are probably related to the type of motor performance the particular terrestrial vertebrates are capable of. PMID:3289562

  2. Neutrino-nucleus reactions based on recent structure studies

    SciTech Connect

    Suzuki, Toshio

    2015-05-15

    Neutrino-nucleus reactions are studied with the use of new shell model Hamiltonians, which have proper tensor components in the interactions and prove to be successful in the description of Gamow-Teller (GT) strengths in nuclei. The new Hamiltonians are applied to obtain new neutrino-nucleus reaction cross sections in {sup 12}C, {sup 13}C, {sup 56}Fe and {sup 56}Ni induced by solar and supernova neutrinos. The element synthesis by neutrino processes in supernova explosions is discussed with the new cross sections. The enhancement of the production yields of {sup 7}Li, {sup 11}B and {sup 55}Mn is obtained while fragmented GT strength in {sup 56}Ni with two-peak structure is found to result in smaller e-capture rates at stellar environments. The monopole-based universal interaction with tensor force of π+ρ meson exchanges is used to evaluate GT strength in {sup 40}Ar and ν-induced reactions on {sup 40}Ar. It is found to reproduce well the experimental GT strength in {sup 40}Ar.

  3. Formation of the avian nucleus magnocellularis from the auditory anlage.

    PubMed

    Hendricks, Susan J; Rubel, Edwin W; Nishi, Rae

    2006-10-01

    In the avian auditory system, the neural network for computing the localization of sound in space begins with bilateral innervation of nucleus laminaris (NL) by nucleus magnocellularis (NM) neurons. We used antibodies against the neural specific markers Hu C/D, neurofilament, and SV2 together with retrograde fluorescent dextran labeling from the contralateral hindbrain to identify NM neurons within the anlage and follow their development. NM neurons could be identified by retrograde labeling as early as embryonic day (E) 6. While the auditory anlage organized itself into NM and NL in a rostral-to-caudal fashion between E6 and E8, labeled NM neurons were visible throughout the extent of the anlage at E6. By observing the pattern of neuronal rearrangements together with the pattern of contralaterally projecting NM fibers, we could identify NL in the ventral anlage. Ipsilateral NM fibers contacted the developing NL at E8, well after NM collaterals had projected contralaterally. Furthermore, the formation of ipsilateral connections between NM and NL neurons appeared to coincide with the arrival of VIIIth nerve fibers in NM. By E10, immunoreactivity for SV2 was heavily concentrated in the dorsal and ventral neuropils of NL. Thus, extensive pathfinding and morphological rearrangement of central auditory nuclei occurs well before the arrival of cochlear afferents. Our results suggest that NM neurons may play a central role in formation of tonotopic connections in the auditory system.

  4. Suppression of the swallowing reflex by stimulation of the red nucleus.

    PubMed

    Satoh, Yoshihide; Tsuji, Kojun; Tsujimura, Takanori; Ishizuka, Ken'Ichi; Inoue, Makoto

    2015-07-01

    We study whether the red nucleus is involved in control of swallowing. The swallowing reflex was induced in anesthetized rats by repetitive electrical stimulation of the superior laryngeal nerve. The electromyographic activities of the mylohyoid and thyrohyoid muscles were recorded in order to identify the swallowing reflex. Repetitive electrical stimulation applied to the red nucleus reduced the number of swallows. The onset latency of the first swallow was increased during repetitive electrical stimulation applied to the magnocellular part of the red nucleus. Microinjection of monosodium glutamate into the red nucleus also reduced the number of swallows. The onset latency of the first swallow was increased after microinjection of monosodium glutamate into the magnocellular part of the red nucleus. These results imply that the red nucleus is involved in the control of swallowing.

  5. Effects of systemic L-tyrosine on dopamine release from rat corpus striatum and nucleus accumbens

    NASA Technical Reports Server (NTRS)

    During, Matthew J.; Acworth, Ian N.; Wurtman, Richard J.

    1988-01-01

    Intracerebral dialysis was used to monitor extracellular fluid from rat striatum and nucleus accumbens following the intraperitoneal administration of tyrosine. Dopamine concentrations in dialysates from both the striatum and the nucleus accumbens increased significantly in response to the tyrosine. The magnitude of the tyrosine effect was greater in the nucleus accumbens than in the striatum. Hence, mesolimbic dopaminergic neurons may be especially responsive to precursor availability.

  6. Role of the lateral reticular nucleus in suppressing the jaw-opening reflex following stimulation of the red nucleus.

    PubMed

    Satoh, Yoshihide; Yajima, Eriko; Ishizuka, Ken'Ichi; Iwasaki, Shin-ichi

    2014-03-01

    We found in a previous study that stimulation of the red nucleus (RN) facilitated the low-threshold afferent-evoked jaw-opening reflex (JOR) and suppressed the high-threshold afferent-evoked JOR. It has been reported that the RN projections to the contralateral lateral reticular nucleus (LRt), and stimulation of the LRt inhibits the nociceptive JOR. These facts suggest that RN-induced modulation of the JOR is mediated via the LRt. We investigated whether electrically induced lesions of the LRt, or microinjection of muscimol into the LRt, affects RN-induced modulation of the JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was either 1.2 (low-threshold) or 4.0 (high-threshold) times the threshold. Electrically induced lesion of the LRt and microinjection of muscimol into the LRt reduced the RN-induced suppression of the high-threshold afferent-evoked JOR, but did not affect the RN-induced facilitation of the low-threshold afferent-evoked JOR. These results suggest that the RN-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the contralateral LRt. PMID:24370814

  7. Role of the red nucleus in suppressing the jaw-opening reflex following stimulation of the raphe magnus nucleus.

    PubMed

    Satoh, Yoshihide; Ishizuka, Ken'Ichi; Iwasaki, Shin-ichi

    2014-08-01

    In a previous study, we found that electrical and chemical stimulation of the red nucleus (RN) suppressed the high-threshold afferent-evoked jaw-opening reflex (JOR). It has been reported that the RN receives bilaterally projection fibers from the raphe magnus nucleus (RMg), and that stimulation of the RMg inhibits the tooth pulp-evoked nociceptive JOR. These facts imply that RMg-induced inhibition of the JOR could be mediated via the RN. The present study first examines whether stimulation of the RMg suppresses the high-threshold afferent-evoked JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was 4.0 (high-threshold) times the threshold. Conditioning electrical stimulation of the RMg significantly suppressed the JOR. A further study then examined whether electrically induced lesions of the RN or microinjection of muscimol into the RN affects RMg-induced suppression of the JOR. Electrically induced lesions of the bilateral RN and microinjection of muscimol into the bilateral RN both reduced the RMg-induced suppression of the JOR. These results suggest that RMg-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the RN. PMID:24929104

  8. Topography and morphology of the inhibitory projection from superior olivary nucleus to nucleus laminaris in chickens (Gallus gallus).

    PubMed

    Tabor, Kathryn M; Wong, Rachel O L; Rubel, Edwin W

    2011-02-01

    The avian nucleus laminaris (NL) is involved in computation of interaural time differences (ITDs) that encode the azimuthal position of a sound source. Neurons in NL are bipolar, with dorsal and ventral dendritic arbors receiving input from separate ears. NL neurons act as coincidence detectors that respond maximally when input from each ear arrives at the two dendritic arbors simultaneously. Computational and physiological studies demonstrated that the sensitivity of NL neurons to coincident inputs is modulated by an inhibitory feedback circuit via the superior olivary nucleus (SON). To understand the mechanism of this modulation, the topography of the projection from SON to NL was mapped, and the morphology of the axon terminals of SON neurons in NL was examined in chickens (Gallus gallus). In vivo injection of AlexaFluor 568 dextran amine into SON demonstrated a coarse topographic projection from SON to NL. Retrogradely labeled neurons in NL were located within the zone of anterogradely labeled terminals, suggesting a reciprocal projection between SON to NL. In vivo extracellular physiological recording further demonstrated that this topography is consistent with tonotopic maps in SON and NL. In addition, three-dimensional reconstruction of single SON axon branches within NL revealed that individual SON neurons innervate a large area of NL and terminate on both dorsal and ventral dendritic arbors of NL neurons. The organization of the projection from SON to NL supports its proposed functions of controlling the overall activity level of NL and enhancing the specificity of frequency mapping and ITD detection.

  9. Epidermal growth factor receptors destined for the nucleus are internalized via a clathrin-dependent pathway

    SciTech Connect

    De Angelis Campos, Ana Carolina; Rodrigues, Michele Angela; Andrade, Carolina de; Miranda de Goes, Alfredo; Nathanson, Michael H.; Gomes, Dawidson A.

    2011-08-26

    Highlights: {yields} EGF and its receptor translocates to the nucleus in liver cells. {yields} Real time imaging shows that EGF moves to the nucleus. {yields} EGF moves with its receptor to the nucleus. {yields} Dynamin and clathrin are necessary for EGFR nuclear translocation. -- Abstract: The epidermal growth factor (EGF) transduces its actions via the EGF receptor (EGFR), which can traffic from the plasma membrane to either the cytoplasm or the nucleus. However, the mechanism by which EGFR reaches the nucleus is unclear. To investigate these questions, liver cells were analyzed by immunoblot of cell fractions, confocal immunofluorescence and real time confocal imaging. Cell fractionation studies showed that EGFR was detectable in the nucleus after EGF stimulation with a peak in nuclear receptor after 10 min. Movement of EGFR to the nucleus was confirmed by confocal immunofluorescence and labeled EGF moved with the receptor to the nucleus. Small interference RNA (siRNA) was used to knockdown clathrin in order to assess the first endocytic steps of EGFR nuclear translocation in liver cells. A mutant dynamin (dynamin K44A) was also used to determine the pathways for this traffic. Movement of labeled EGF or EGFR to the nucleus depended upon dynamin and clathrin. This identifies the pathway that mediates the first steps for EGFR nuclear translocation in liver cells.

  10. Morphological and morphometric characterisation of Onuf's nucleus in the spinal cord in man

    PubMed Central

    PULLEN, A. H.; TUCKER, D.; MARTIN, J. E.

    1997-01-01

    In the absence of a systematic morphometric study of Onuf's nucleus in man, this investigation defines the limits of variation of segmental position and the range of length and volume of Onuf's nucleus in 6 normal humans displaying no neurological disease (2 males, 4 females). Serial section reconstruction methods in conjunction with the disector method provided information on the numbers, sizes and shapes of the constituent motor neurons of Onuf's nucleus. In contrast to previous descriptions, the cranial origin of Onuf's nucleus occurred in rostral S1 in 50% of subjects, and midcaudal S1 in the remaining subjects. Onuf's nucleus varied in length between 4 and 7 mm, and was 0.2–0.37 mm3 in volume. Differences in length or volume between males or females, or between the left and right side of the cord were not statistically significant. Neurons in Onuf's nucleus varied in diameter between 10 μm and 60 μm (mean 26 μm) and their mean number was 625±137. A higher density of neurons occurred at the cranial and caudal ends of the nucleus relative to the middle. While 37% of neurons were approximately spherical (shape index ∼1), 44% were ellipsoid and 19% fusiform (shape indices varying between 0.26 and 0.8). These findings are compared with previous studies of Onuf's nucleus in man and animals. The results form a basis for further studies on Onuf's nucleus in normality and neurodegenerative diseases. PMID:9306197

  11. Rodent anxiety and kindling of the central amygdala and nucleus basalis.

    PubMed

    Adamec, R; Shallow, T

    We studied lasting behavioral effects of kindling of three parts of the central nucleus of the amygdala and the anterior nucleus basalis in the right hemisphere of male Wistar rats. Kindling lastingly changed two measures of anxiety in the elevated plus-maze. The nature of the change depended on the location of the kindled focus. Kindling of the posterior central nucleus decreased both open-arm exploration and frequency of risk assessment in the elevated plus-maze 1 week after the fourth stage 5 seizure. Kindling of the middle parts of the central nucleus was without behavioral effects. Kindling of the anterior central nucleus and the anterior nucleus basalis increased risk assessment, which was interpreted as an anxiolytic effect. Changes in risk assessment produced by kindling of the central nucleus were dependent on open-arm avoidance, whereas the effects of nucleus basalis kindling were independent of open-arm avoidance. Analysis of covariance and factor analysis support the view that control of risk assessment is by circuitry, which is independent of that which controls open-arm avoidance. Moreover, part of this circuitry appears to involve the anterior nucleus basalis. Changes in plus-maze behavior were independent of changes in exploration or activity in either the plus-maze or hole board. These findings add to a growing body of evidence that suggests that subtle differences in location of a kindled focus within the rat amygdala lead to different behavioral outcomes.

  12. Probing the Nucleus with Deuteron+Gold Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Citron, Zvi Hirsh

    2011-12-01

    The Relativistic Heavy Ion Collider (RHIC) was built to produce and study Quark Gluon Plasma (QGP), the phase of matter thought to exist under conditions sufficiently hot and dense to create a medium in which the degrees of freedom are quarks and gluons rather than color neutral hadrons. Already in its early years of running, the data from RHIC provided tantalizing evidence of QGP signatures in Au+Au collisions at sNN = 200 GeV. A crucial part of understanding the putative QGP in Au+Au collisions is to have both a well understood reference as well as a robust control experiment. Proton-proton collisions at the same sNN serve as the baseline for heavy ion collisions at RHIC, and play an invaluable role in setting our frame of reference in interactions that do not create any nuclear medium. For the control experiment, RHIC's ability to collide asymmetric beams is utilized and d+Au collisions are used. Unlike p+p collisions, in the d+Au system there is a nuclear medium present---the heavy Au nucleus---and so we may study this system to distinguish initial state cold nuclear matter effects from final state effects that occur in the hot dense medium of Au+Au collisions. Beyond its use as a control experiment, the d+Au collision system presents the opportunity for important study of nuclear and nucleonic structure, it is after all necessary for our colored parton theory to operate in the nucleus as well as in a QGP. Deuteron - gold collisions at RHIC are a powerful tool for shedding light on cold nuclear matter effects. This thesis describes two analyses of d+Au collisions measured by the PHENIX experiment at RHIC. The first is a measurement of the midrapidity yield of unidentified charged hadrons in the 2003 RHIC run. This is used a key baseline for understanding particle production in Au+Au collisions as well as a detailed look at the Cronin effect. The second analysis measures rapidity separated two-particle production where one of the particles is at either forward

  13. Characteristics of near response cells projecting to the oculomotor nucleus.

    PubMed

    Zhang, Y; Mays, L E; Gamlin, P D

    1992-04-01

    1. Previous work has shown neurons just dorsal and lateral to the oculomotor nucleus that increase their firing rate with increases in the angle of ocular convergence. It has been suggested that the output of these midbrain near response cells might provide the vergence command needed by the medial rectus motoneurons. However, lens accommodation ordinarily accompanies convergence, and a subsequent study showed that only about one-half of these midbrain near response cells carried a signal related exclusively to vergence. One hypothesis suggested by this finding is that this subgroup of neurons might have a unique role in providing a "pure" vergence signal to the medial rectus motoneurons. 2. In the present study extracellular recordings were made from midbrain near response cells in monkeys while eye position and lens accommodation were measured. The monkeys viewed targets through an optical system that allowed the accommodative and ocular vergence demands to be manipulated independently. This approach was used to produce a partial dissociation of accommodative and vergence responses, so that an accommodative and vergence coefficient could be determined for each cell, by the use of the following equation FR = R0 + kda x AR + kdv x CR where FR is the firing rate of the near response cell, R0 is the predicted firing rate for a distant target, kda is the (dissociated) accommodation coefficient, AR is the accommodative response, kdv is the (dissociated) vergence coefficient, and CR is the convergence response. 3. The vergence and accommodation coefficients were determined for a large number of midbrain near response cells, including a subset that could be antidromically activated from the medial rectus subdivisions of the oculomotor nucleus. Some near response neurons were found with signals related exclusively to convergence (i.e., kdv greater than 0 and kda = 0), whereas several others had signals related exclusively to lens accommodation (i.e., kda greater than 0

  14. Dipole excitations in the vibrational nucleus 112Cd

    NASA Astrophysics Data System (ADS)

    Lehmann, H.; Nord, A.; de Almeida Pinto, A. E.; Beck, O.; Besserer, J.; von Brentano, P.; Drissi, S.; Eckert, T.; Herzberg, R.-D.; Jäger, D.; Jolie, J.; Kneissl, U.; Margraf, J.; Maser, H.; Pietralla, N.; Pitz, H. H.

    1999-08-01

    The strength distribution of low-lying dipole excitations in the medium-weight vibrational nucleus 112Cd was investigated by means of nuclear resonance fluorescence experiments (NRF) performed at the bremsstrahlung beam of the Stuttgart Dynamitron accelerator (end-point energy 4.1 MeV). Detailed information on excitation energies, spins, decay widths, and transition probabilities of about 20 new spin-1 states in 112Cd has been obtained. In comparison with comprehensive spectroscopic information available for 112Cd conclusions on the parities of the lowest states can be made. A strongly excited Jπ=1- state is interpreted as the 1- member of the quadrupole-octupole coupled quintuplet. The observed transition intensities are described in the framework of the interacting boson model and compared with those obtained from recent nuclear resonance fluorescence experiments on the neighboring Cd isotopes 113,114Cd.

  15. Physiological importance of a circadian clock outside the suprachiasmatic nucleus.

    PubMed

    Storch, K-F; Paz, C; Signorovitch, J; Raviola, E; Pawlyk, B; Li, T; Weitz, C J

    2007-01-01

    Circadian clocks are widely distributed in mammalian tissues, but little is known about the physiological functions of clocks outside the suprachiasmatic nucleus of the brain. The retina has an intrinsic circadian clock, but its importance for vision is unknown. Here, we show that mice lacking Bmal1, a gene required for clock function, had abnormal retinal transcriptional responses to light and defective inner retinal electrical responses to light, but normal photoreceptor responses to light and retinas that appeared structurally normal as observed by light and electron microscopy. We generated mice with a retina-specific genetic deletion of Bmal1, and they had defects of retinal visual physiology essentially identical to those of mice lacking Bmal1 in all tissues and lacked a circadian rhythm of inner retinal electrical responses to light. Our findings indicate that the intrinsic circadian clock of the retina regulates retinal visual processing in vivo.

  16. Plastid-nucleus communication involves calcium-modulated MAPK signalling

    PubMed Central

    Guo, Hailong; Feng, Peiqiang; Chi, Wei; Sun, Xuwu; Xu, Xiumei; Li, Yuan; Ren, Dongtao; Lu, Congming; David Rochaix, Jean; Leister, Dario; Zhang, Lixin

    2016-01-01

    Chloroplast retrograde signals play important roles in coordinating the plastid and nuclear gene expression and are critical for proper chloroplast biogenesis and for maintaining optimal chloroplast functions in response to environmental changes in plants. Until now, the signals and the mechanisms for retrograde signalling remain poorly understood. Here we identify factors that allow the nucleus to perceive stress conditions in the chloroplast and to respond accordingly by inducing or repressing specific nuclear genes encoding plastid proteins. We show that ABI4, which is known to repress the LHCB genes during retrograde signalling, is activated through phosphorylation by the MAP kinases MPK3/MPK6 and the activity of these kinases is regulated through 14-3-3ω-mediated Ca2+-dependent scaffolding depending on the chloroplast calcium sensor protein CAS. These findings uncover an additional mechanism in which chloroplast-modulated Ca2+ signalling controls the MAPK pathway for the activation of critical components of the retrograde signalling chain. PMID:27399341

  17. Serotonin neurons in the dorsal raphe nucleus encode reward signals.

    PubMed

    Li, Yi; Zhong, Weixin; Wang, Daqing; Feng, Qiru; Liu, Zhixiang; Zhou, Jingfeng; Jia, Chunying; Hu, Fei; Zeng, Jiawei; Guo, Qingchun; Fu, Ling; Luo, Minmin

    2016-01-28

    The dorsal raphe nucleus (DRN) is involved in organizing reward-related behaviours; however, it remains unclear how genetically defined neurons in the DRN of a freely behaving animal respond to various natural rewards. Here we addressed this question using fibre photometry and single-unit recording from serotonin (5-HT) neurons and GABA neurons in the DRN of behaving mice. Rewards including sucrose, food, sex and social interaction rapidly activate 5-HT neurons, but aversive stimuli including quinine and footshock do not. Both expected and unexpected rewards activate 5-HT neurons. After mice learn to wait for sucrose delivery, most 5-HT neurons fire tonically during waiting and then phasically on reward acquisition. Finally, GABA neurons are activated by aversive stimuli but inhibited when mice seek rewards. Thus, DRN 5-HT neurons positively encode a wide range of reward signals during anticipatory and consummatory phases of reward responses. Moreover, GABA neurons play a complementary role in reward processing.

  18. Kinetics and mechanism of DNA uptake into the cell nucleus

    PubMed Central

    Salman, H.; Zbaida, D.; Rabin, Y.; Chatenay, D.; Elbaum, M.

    2001-01-01

    Gene transfer to eukaryotic cells requires the uptake of exogenous DNA into the cell nucleus. Except during mitosis, molecular access to the nuclear interior is limited to passage through the nuclear pores. Here we demonstrate the nuclear uptake of extended linear DNA molecules by a combination of fluorescence microscopy and single-molecule manipulation techniques, using the latter to follow uptake kinetics of individual molecules in real time. The assays were carried out on nuclei reconstituted in vitro from extracts of Xenopus eggs, which provide both a complete complement of biochemical factors involved in nuclear protein import, and unobstructed access to the nuclear pores. We find that uptake of DNA is independent of ATP or GTP hydrolysis, but is blocked by wheat germ agglutinin. The kinetics are much slower than would be expected from hydrodynamic considerations. A fit of the data to a simple model suggests femto-Newton forces and a large friction relevant to the uptake process. PMID:11390964

  19. Semi-inclusive charged-current neutrino-nucleus reactions

    DOE PAGESBeta

    Moreno, O.; Donnelly, T. W.; Van Orden, J. W.; Ford, W. P.

    2014-07-17

    The general, universal formalism for semi-inclusive charged-current (anti)neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case ofmore » the hadronic responses, general symmetry principles are invoked to determine which contributions can occur. As a result, the general leptonic-hadronic tensor contraction is given as well as the cross section for the process.« less

  20. Semi-inclusive charged-current neutrino-nucleus reactions

    SciTech Connect

    Moreno, O.; Donnelly, T. W.; Van Orden, J. W.; Ford, W. P.

    2014-07-17

    The general, universal formalism for semi-inclusive charged-current (anti)neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case of the hadronic responses, general symmetry principles are invoked to determine which contributions can occur. As a result, the general leptonic-hadronic tensor contraction is given as well as the cross section for the process.

  1. Circadian rhythm. Dysrhythmia in the suprachiasmatic nucleus inhibits memory processing.

    PubMed

    Fernandez, Fabian; Lu, Derek; Ha, Phong; Costacurta, Patricia; Chavez, Renee; Heller, H Craig; Ruby, Norman F

    2014-11-14

    Chronic circadian dysfunction impairs declarative memory in humans but has little effect in common rodent models of arrhythmia caused by clock gene knockouts or surgical ablation of the suprachiasmatic nucleus (SCN). An important problem overlooked in these translational models is that human dysrhythmia occurs while SCN circuitry is genetically and neurologically intact. Siberian hamsters (Phodopus sungorus) are particularly well suited for translational studies because they can be made arrhythmic by a one-time photic treatment that severely impairs spatial and recognition memory. We found that once animals are made arrhythmic, subsequent SCN ablation completely rescues memory processing. These data suggest that the inhibitory effects of a malfunctioning SCN on cognition require preservation of circuitry between the SCN and downstream targets that are lost when these connections are severed.

  2. Dysrhythmia in the suprachiasmatic nucleus inhibits memory processing

    PubMed Central

    Fernandez, Fabian; Lu, Derek; Ha, Phong; Costacurta, Patricia; Chavez, Renee; Heller, H. Craig; Ruby, Norman F.

    2015-01-01

    Chronic circadian dysfunction impairs declarative memory in humans but has little effect in common rodent models of arrhythmia caused by clock gene knockouts or surgical ablation of the suprachiasmatic nucleus (SCN). An important problem overlooked in these translational models is that human dysrhythmia occurs while SCN circuitry is genetically and neurologically intact. Siberian hamsters (Phodopus sungorus) are particularly well suited for translational studies because they can be made arrhythmic by a one-time photic treatment that severely impairs spatial and recognition memory. We found that once animals are made arrhythmic, subsequent SCN ablation completely rescues memory processing. These data suggest that the inhibitory effects of a malfunctioning SCN on cognition require preservation of circuitry between the SCN and downstream targets that are lost when these connections are severed. PMID:25395537

  3. Total absorption spectroscopy of N = 51 nucleus 85Se

    NASA Astrophysics Data System (ADS)

    Goetz, K. C.; Grzywacz, R. K.; Rykaczewski, K. P.; Karny, M.; Fialkowska, A.; Wolinska-Cichocka, M.; Rasco, B. C.; Zganjar, E. F.; Johnson, J. W.; Gross, C. J.

    2014-09-01

    An experimental campaign utilizing the Modular Total Absorption Spectrometer (MTAS) was conducted at the HRIBF facility in January of 2012. The campaign studied 22 isotopes, many of which were identified as the highest priority for decay heat analysis during a nuclear fuel cycle, see the report by the OECD-IAEA Nuclear Energy Agency in 2007. The case of 85Se will be discussed. 85Se is a Z = 34, N = 51 nucleus with the valence neutron located in the positive parity sd single particle state. Therefore, its decay properties are determined by interplay between first forbidden decays of the valence neutron and Gamow-Teller decay of a 78Ni core. Analysis of the data obtained during the January 2012 run indicates a significant increase of the beta strength function when compared with previous measurements, see Ref..

  4. One-pion production in neutrino-nucleus collisions

    SciTech Connect

    Hernández, E.; Nieves, J.; Vicente-Vacas, J. M.

    2015-05-15

    We use our model for neutrino pion production on the nucleon to study pion production on a nucleus. The model is conveniently modified to include in-medium corrections and its validity is extended up to 2 GeV neutrino energies by the inclusion of new resonant contributions in the production process. Our results are compared with recent MiniBooNE data measured in mineral oil. Our total cross sections are below data for neutrino energies above ≈ 1 GeV. As with other theoretical calculations, the agreement with data improves if we neglect pion final state interaction. This is also the case for differential cross sections convoluted over the neutrino flux.

  5. Role of the nucleus in apoptosis: signaling and execution.

    PubMed

    Prokhorova, Evgeniia A; Zamaraev, Alexey V; Kopeina, Gelina S; Zhivotovsky, Boris; Lavrik, Inna N

    2015-12-01

    Since their establishment in the early 1970s, the nuclear changes upon apoptosis induction, such as the condensation of chromatin, disassembly of nuclear scaffold proteins and degradation of DNA, were, and still are, considered as the essential steps and hallmarks of apoptosis. These are the characteristics of the execution phase of apoptotic cell death. In addition, accumulating data clearly show that some nuclear events can lead to the induction of apoptosis. In particular, if DNA lesions resulting from deregulation during the cell cycle or DNA damage induced by chemotherapeutic drugs or viral infection cannot be efficiently eliminated, apoptotic mechanisms, which enable cellular transformation to be avoided, are activated in the nucleus. The functional heterogeneity of the nuclear organization allows the tight regulation of these signaling events that involve the movement of various nuclear proteins to other intracellular compartments (and vice versa) to initiate and govern apoptosis. Here, we discuss how these events are coordinated to execute apoptotic cell death.

  6. Input/output properties of the lateral vestibular nucleus

    NASA Technical Reports Server (NTRS)

    Boyle, R.; Bush, G.; Ehsanian, R.

    2004-01-01

    This article is a review of work in three species, squirrel monkey, cat, and rat studying the inputs and outputs from the lateral vestibular nucleus (LVN). Different electrophysiological shock paradigms were used to determine the synaptic inputs derived from thick to thin diameter vestibular nerve afferents. Angular and linear mechanical stimulations were used to activate and study the combined and individual contribution of inner ear organs and neck afferents. The spatio-temporal properties of LVN neurons in the decerebrated rat were studied in response to dynamic acceleration inputs using sinusoidal linear translation in the horizontal head plane. Outputs were evaluated using antidromic identification techniques and identified LVN neurons were intracellularly injected with biocytin and their morphology studied.

  7. Synchronization of Cellular Clocks in the Suprachiasmatic Nucleus

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Shun; Isejima, Hiromi; Matsuo, Takuya; Okura, Ryusuke; Yagita, Kazuhiro; Kobayashi, Masaki; Okamura, Hitoshi

    2003-11-01

    Individual cellular clocks in the suprachiasmatic nucleus (SCN), the circadian center, are integrated into a stable and robust pacemaker with a period length of about 24 hours. We used real-time analysis of gene expression to show synchronized rhythms of clock gene transcription across hundreds of neurons within the mammalian SCN in organotypic slice culture. Differentially phased neuronal clocks are topographically arranged across the SCN. A protein synthesis inhibitor set all cell clocks to the same initial phase and, after withdrawal, intrinsic interactions among cell clocks reestablished the stable program of gene expression across the assemblage. Na+-dependent action potentials contributed to establishing cellular synchrony and maintaining spontaneous oscillation across the SCN.

  8. Nucleus management with Blumenthal technique: Anterior chamber maintainer

    PubMed Central

    Malik, Krishnan P S; Goel, Ruchi

    2009-01-01

    The Blumenthal's ‘Mininuc’ technique enables nuclear expression through a 5-6.5-mm sclerocorneal tunnel incision using a Sheet's lens glide and anterior chamber maintainer (ACM). A 6-mm or larger capsulorrhexis, reduction in nuclear size by hydroprocedure and its manipulation manually into the anterior chamber are performed. The nucleus is expressed out of the chamber by use of hydrostatic pressure created by balanced salt solution delivered continuously through the ACM. This continuous flow from ACM to anterior chamber keeps the eye under positive pressure physiological state besides clearing the chamber of cortex, blood and pigments offering excellent visualization. The procedure, with an initial learning curve, is highly effective, applicable to all grades of cataracts, has minimum intraocular instrumentation resulting in an early rehabilitation of the patient. PMID:19075404

  9. Models of chromatin spatial organisation in the cell nucleus

    NASA Astrophysics Data System (ADS)

    Nicodemi, Mario

    2014-03-01

    In the cell nucleus chromosomes have a complex architecture serving vital functional purposes. Recent experiments have started unveiling the interaction map of DNA sites genome-wide, revealing different levels of organisation at different scales. The principles, though, which orchestrate such a complex 3D structure remain still mysterious. I will overview the scenario emerging from some classical polymer physics models of the general aspect of chromatin spatial organisation. The available experimental data, which can be rationalised in a single framework, support a picture where chromatin is a complex mixture of differently folded regions, self-organised across spatial scales according to basic physical mechanisms. I will also discuss applications to specific DNA loci, e.g. the HoxB locus, where models informed with biological details, and tested against targeted experiments, can help identifying the determinants of folding.

  10. Serotonin neurons in the dorsal raphe nucleus encode reward signals

    PubMed Central

    Li, Yi; Zhong, Weixin; Wang, Daqing; Feng, Qiru; Liu, Zhixiang; Zhou, Jingfeng; Jia, Chunying; Hu, Fei; Zeng, Jiawei; Guo, Qingchun; Fu, Ling; Luo, Minmin

    2016-01-01

    The dorsal raphe nucleus (DRN) is involved in organizing reward-related behaviours; however, it remains unclear how genetically defined neurons in the DRN of a freely behaving animal respond to various natural rewards. Here we addressed this question using fibre photometry and single-unit recording from serotonin (5-HT) neurons and GABA neurons in the DRN of behaving mice. Rewards including sucrose, food, sex and social interaction rapidly activate 5-HT neurons, but aversive stimuli including quinine and footshock do not. Both expected and unexpected rewards activate 5-HT neurons. After mice learn to wait for sucrose delivery, most 5-HT neurons fire tonically during waiting and then phasically on reward acquisition. Finally, GABA neurons are activated by aversive stimuli but inhibited when mice seek rewards. Thus, DRN 5-HT neurons positively encode a wide range of reward signals during anticipatory and consummatory phases of reward responses. Moreover, GABA neurons play a complementary role in reward processing. PMID:26818705

  11. Psychosis post corona radiata and lentiform nucleus infarction.

    PubMed

    Abdullah, Khadijah Hasanah Abang; Saini, Suriati Mohamed; Sharip, Shalisah; Rahman, Abdul Hamid Abdul

    2015-04-02

    Complications of stroke can include neuropsychiatric symptoms. However, post-stroke psychosis is rare. We report a case where an acute presentation of psychosis, depression and fluctuating cognitive impairment in a middle-aged man turned out to be related to a silent brain infarction. The patient had a background of poorly controlled type 2 diabetes mellitus with glycated haemoglobin level of 9.0-11.0%, hypertension and ischaemic heart disease. His CT brain results showed multifocal infarct with hypodensities at bilateral lentiform nucleus and bilateral corona radiata. His strong genetic predisposition of psychosis and a history of brief psychotic disorder with complete remission 3 years prior to the current presentation might possibly contribute to his post-stroke atypical neuropsychiatric presentation, and posed diagnostic challenges. He showed marked improvement with risperidone 6 mg nocte, chlorpromazine 50 mg nocte and fluvoxamine of 200 mg nocte. The need of comprehensive treatments to modify his stroke risk factors was addressed.

  12. Hadron dynamics in high-energy pion-nucleus scattering

    SciTech Connect

    Johnson, M.B.

    1992-12-31

    It is argued that pion-nucleus scattering at high energy (above 300 MeV) is likely to be easier to interpret than it has been at lower energies where the {Delta}{sub 33} resonance dominates. We establish this by examining the relative importance of various dynamic ingredients of scattering theory for high-energy pions and comparing different versions of the theory: a ``model-exact`` microscopic optical model and an eikonal approximation. For nuclei as heavy as Ca, the eikonal theory is an excellent approximation to the full theory for the angular distribution out to the position of the second minimum in the cross section. The prospects for using high-energy pions to examine modifications of nucleons and baryon resonances in nuclei, nuclear structure, exchange currents, short-range correlations, and to characterize pion propagation are discussed.

  13. The suprachiasmatic nucleus: age-related decline in biological rhythms.

    PubMed

    Nakamura, Takahiro J; Takasu, Nana N; Nakamura, Wataru

    2016-09-01

    Aging is associated with changes in sleep duration and quality, as well as increased rates of pathologic/disordered sleep. While several factors contribute to these changes, emerging research suggests that age-related changes in the mammalian central circadian clock within the suprachiasmatic nucleus (SCN) may be a key factor. Prior work from our group suggests that circadian output from the SCN declines because of aging. Furthermore, we have previously observed age-related infertility in female mice, caused by a mismatch between environmental light-dark cycles and the intrinsic, internal biological clocks. In this review, we address regulatory mechanisms underlying circadian rhythms in mammals and summarize recent literature describing the effects of aging on the circadian system.

  14. Laser-nucleus interactions: The quasi-adiabatic regime

    NASA Astrophysics Data System (ADS)

    Pálffy, Adriana; Buss, Oliver; Hoefer, Axel; Weidenmüller, Hans A.

    2015-10-01

    The interaction between nuclei and a strong zeptosecond laser pulse with coherent MeV photons is investigated theoretically. We provide a first semiquantitative study of the quasi-adiabatic regime where the photon absorption rate is comparable to the nuclear equilibration rate. In that regime, multiple photon absorption leads to the formation of a compound nucleus in the so-far unexplored regime of excitation energies several hundred MeV above the yrast line. The temporal dynamics of the process is investigated by means of a set of master equations that account for dipole absorption, stimulated dipole emission, neutron decay, and induced fission in a chain of nuclei. That set is solved numerically by means of state-of-the-art matrix exponential methods also used in nuclear fuel burn-up and radioactivity transport calculations. Our quantitative estimates predict the excitation path and range of nuclei reached by neutron decay and provide relevant information for the layout of future experiments.

  15. MINER{nu}A, a Neutrino--Nucleus Interaction Experiment

    SciTech Connect

    Solano Salinas, C. J.; Chamorro, A.; Romero, C.

    2007-10-26

    With the fantastic results of KamLAND and SNO for neutrino physics, a new generation of neutrino experiments are being designed and build, specially to study the neutrino oscillations to resolve most of the incognita still we have in the neutrino physics. At FERMILAB we have the experiments MINOS and, in a near future, NO{nu}A, to study this kind of oscillations. One big problem these experiments will have is the lack of a good knowledge of the Physics of neutrino interactions with matter, and this will generate big systematic errors. MINER{nu}A, also at FERMILAB, will cover this space studying with high statistics and great precision the neutrino--nucleus interactions.

  16. Mechanical and SEM analysis of artificial comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Thiel, K.; Kochan, H.; Roessler, K.; Gruen, E.; Schwehm, G.; Hellmann, H.; Hsiung, P.; Koelzer, G.

    1989-01-01

    Since 1987 experiments dealing with comet nucleus phenomena have been carried out in the DFVLR space simulation chambers. The main objective of these experiments is a better understanding of thermal behavior, surface phenomena and especially the gas dust interaction. As a function of different sample compositions and exposure to solar irradiation (xenon-bulbs) crusts of different hardness and thickness were measured. The measuring device consists of a motor driven pressure foot (5 mm diameter), which is pressed into the sample. The applied compressive force is electronically monitored. The microstructure of the crust and dust residuals is investigated by scanning electron microscopy (SEM) techniques. Stress-depth profiles of an unirradiated and an irradiated model comet are given.

  17. Integral-Field Spectroscopy of the Centaurus A Nucleus

    NASA Astrophysics Data System (ADS)

    Krajnović, Davor; Sharp, Rob; Thatte, Niranjan

    We report integral-field spectroscopic observations with the Cambridge Infra-Red Panoramic Survey Spectrograph (CIRPASS) mounted on the GEMINI South telescope of the nucleus of the nearby elliptical NGC 5128 (Centaurus A). We detect 2-dimensional distributions of the following emission-lines: [P II], [Fe II] and Paschen β and extract spatially resolved 2D kinematics of Paβ and [Fe II] emission- lines only. The kinematics of the two emission-lines are similar, but the Paβvelocity gradient is steeper in the centre while the velocity dispersion is low everywhere. Assuming simple disk geometry we estimate the mass of the central black hole. We obtain M_• = 8.25+2.25 -4.25 × 107 M⊙, for PA = -3ˆ and i=25ˆ, excluding the M_• - σ relation prediction at a 3σ confidence level, which is in good agreement with previous studies.

  18. Nucleus accumbens core lesions enhance two-way active avoidance

    PubMed Central

    Lichtenberg, Nina T.; Kashtelyan, Vadim; Burton, Amanda C.; Bissonette, Gregory B.; Roesch, Matthew R.

    2014-01-01

    The majority of work examining nucleus accumbens core (NAc) has focused on functions pertaining to behaviors guided by appetitive outcomes. These studies have pointed to NAc as being critical for motivating behavior toward desirable outcomes. For example, we have recently shown that lesions of NAc impaired performance on a reward-guided decision-making task that required rats to choose between differently valued rewards. Unfortunately, much less is known about the role that NAc plays in motivating behavior when aversive outcomes are predicted. To address this issue we asked if NAc lesions impact performance on a two-way active avoidance task in which rats must learn to shuttle back and forth in a behavioral training box in order to avoid a footshock predicted by an auditory tone. Although bilateral NAc lesions initially impaired reward-guided decision-making, we found that the same lesions improved acquisition and retention of two-way active avoidance. PMID:24275320

  19. The dolphin cochlear nucleus: topography, histology and functional implications.

    PubMed

    Malkemper, E P; Oelschläger, H H A; Huggenberger, S

    2012-02-01

    Despite the outstanding auditory capabilities of dolphins, there is only limited information available on the cytology of the auditory brain stem nuclei in these animals. Here, we investigated the cochlear nuclei (CN) of five brains of common dolphins (Delphinus delphis) and La Plata dolphins (Pontoporia blainvillei) using cell and fiber stain microslide series representing the three main anatomical planes. In general, the CN in dolphins comprise the same set of subnuclei as in other mammals. However, the volume ratio of the dorsal cochlear nucleus (DCN) in relation to the ventral cochlear nucleus (VCN) of dolphins represents a minimum among the mammals examined so far. Because, for example, in cats the DCN is necessary for reflexive orientation of the head and pinnae towards a sound source, the massive restrictions in head movability in dolphins and the absence of outer ears may be correlated with the reduction of the DCN. Moreover, the same set of main neuron types were found in the dolphin CN as in other mammals, including octopus and multipolar cells. Because the latter two types of neurons are thought to be involved in the recognition of complex sounds, including speech, we suggest that, in dolphins, they may be involved in the processing of their communication signals. Comparison of the toothed whale species studied here revealed that large spherical cells were present in the La Plata dolphin but absent in the common dolphin. These neurons are known to be engaged in the processing of low-frequency sounds in terrestrial mammals. Accordingly, in the common dolphin, the absence of large spherical cells seems to be correlated with a shift of its auditory spectrum into the high-frequency range above 20 kHz. The existence of large spherical cells in the VCN of the La Plata dolphin, however, is enigmatic asthis species uses frequencies around 130 kHz. PMID:21987441

  20. The dolphin cochlear nucleus: topography, histology and functional implications.

    PubMed

    Malkemper, E P; Oelschläger, H H A; Huggenberger, S

    2012-02-01

    Despite the outstanding auditory capabilities of dolphins, there is only limited information available on the cytology of the auditory brain stem nuclei in these animals. Here, we investigated the cochlear nuclei (CN) of five brains of common dolphins (Delphinus delphis) and La Plata dolphins (Pontoporia blainvillei) using cell and fiber stain microslide series representing the three main anatomical planes. In general, the CN in dolphins comprise the same set of subnuclei as in other mammals. However, the volume ratio of the dorsal cochlear nucleus (DCN) in relation to the ventral cochlear nucleus (VCN) of dolphins represents a minimum among the mammals examined so far. Because, for example, in cats the DCN is necessary for reflexive orientation of the head and pinnae towards a sound source, the massive restrictions in head movability in dolphins and the absence of outer ears may be correlated with the reduction of the DCN. Moreover, the same set of main neuron types were found in the dolphin CN as in other mammals, including octopus and multipolar cells. Because the latter two types of neurons are thought to be involved in the recognition of complex sounds, including speech, we suggest that, in dolphins, they may be involved in the processing of their communication signals. Comparison of the toothed whale species studied here revealed that large spherical cells were present in the La Plata dolphin but absent in the common dolphin. These neurons are known to be engaged in the processing of low-frequency sounds in terrestrial mammals. Accordingly, in the common dolphin, the absence of large spherical cells seems to be correlated with a shift of its auditory spectrum into the high-frequency range above 20 kHz. The existence of large spherical cells in the VCN of the La Plata dolphin, however, is enigmatic asthis species uses frequencies around 130 kHz.

  1. Sickle hemoglobin gelation. Reaction order and critical nucleus size.

    PubMed Central

    Behe, M J; Englander, S W

    1978-01-01

    Sickle hemoglobin (Hb S) gelation displays kinetics consistent with a rate-limiting nucleation step. The approximate size of the critical nucleus can be inferred from the order of the reaction with respect to Hb S activity, but determination of the reaction order is complicated by the fact that Hb S activity is substantially different from Hb S concentration at the high protein concentrations required for gelation. Equilibrium and kinetic experiments on Hb S gelation were designed to evaluate the relative activity coefficient of Hb S as a function of concentration. These experiments used non-Hb S proteins to mimic, and thus evaluate, the effect on activity coefficients of increasing Hb S concentration. At Hb S concentrations near 20% the change in Hb S activity coefficient generates two-thirds of the apparent dependence of nucleation rate on Hb S concentration. When this effect is explicitly accounted for, the nucleation reaction is seen to be approximately 10th-order with respect to effective number concentration of Hb S. The closeness of the reaction order to the number of strands in models of Hb S fibers suggests a nucleus close to the size of one turn of the Hb S fiber. These experiments introduce a new approach to the study of Hb S gelation, the equal activity isotherm, used here also to show that Hb S.Hb A (normal adult hemoglobin) hybrids do incorporate into growing nuclei and stable microtubules but that A.S hybridization is neutral with respect to promotion of Hb S nucleation and the sol-gel equilibrium. PMID:667302

  2. Intrinsic properties and neuropharmacology of midline paraventricular thalamic nucleus neurons

    PubMed Central

    Kolaj, Miloslav; Zhang, Li; Hermes, Michael L. H. J.

    2014-01-01

    Neurons in the midline and intralaminar thalamic nuclei are components of an interconnected brainstem, limbic and prefrontal cortex neural network that is engaged during arousal, vigilance, motivated and addictive behaviors, and stress. To better understand the cellular mechanisms underlying these functions, here we review some of the recently characterized electrophysiological and neuropharmacological properties of neurons in the paraventricular thalamic nucleus (PVT), derived from whole cell patch clamp recordings in acute rat brain slice preparations. PVT neurons display firing patterns and ionic conductances (IT and IH) that exhibit significant diurnal change. Their resting membrane potential (RMP) is maintained by various ionic conductances that include inward rectifier (Kir), hyperpolarization-activated nonselective cation (HCN) and TWIK-related acid sensitive (TASK) K+ channels. Firing patterns are regulated by high voltage-activated (HVA) and low voltage-activated (LVA) Ca2+ conductances. Moreover, transient receptor potential (TRP)-like nonselective cation channels together with Ca2+- and Na+-activated K+ conductances (KCa; KNa) contribute to unique slow afterhyperpolarizing potentials (sAHPs) that are generally not detectable in lateral thalamic or reticular thalamic nucleus neurons. The excitability of PVT neurons is also modulated by activation of neurotransmitter receptors associated with afferent pathways to PVT and other thalamic midline nuclei. We report on receptor-mediated actions of GABA, glutamate, monoamines and several neuropeptides: arginine vasopressin, gastrin-releasing peptide, thyrotropin releasing hormone and the orexins (hypocretins). This review represents an initial survey of intrinsic and transmitter-sensitive ionic conductances that are deemed to be unique to this population of midline thalamic neurons, information that is fundamental to an appreciation of the role these thalamic neurons may play in normal central nervous system

  3. Complete nucleotide sequence of the chlorarachniophyte nucleomorph: nature's smallest nucleus.

    PubMed

    Gilson, Paul R; Su, Vanessa; Slamovits, Claudio H; Reith, Michael E; Keeling, Patrick J; McFadden, Geoffrey I

    2006-06-20

    The introduction of plastids into different heterotrophic protists created lineages of algae that diversified explosively, proliferated in marine and freshwater environments, and radically altered the biosphere. The origins of these secondary plastids are usually inferred from the presence of additional plastid membranes. However, two examples provide unique snapshots of secondary-endosymbiosis-in-action, because they retain a vestige of the endosymbiont nucleus known as the nucleomorph. These are chlorarachniophytes and cryptomonads, which acquired their plastids from a green and red alga respectively. To allow comparisons between them, we have sequenced the nucleomorph genome from the chlorarachniophyte Bigelowiella natans: at a mere 373,000 bp and with only 331 genes, the smallest nuclear genome known and a model for extreme reduction. The genome is eukaryotic in nature, with three linear chromosomes containing densely packed genes with numerous overlaps. The genome is replete with 852 introns, but these are the smallest introns known, being only 18, 19, 20, or 21 nt in length. These pygmy introns are shown to be miniaturized versions of normal-sized introns present in the endosymbiont at the time of capture. Seventeen nucleomorph genes encode proteins that function in the plastid. The other nucleomorph genes are housekeeping entities, presumably underpinning maintenance and expression of these plastid proteins. Chlorarachniophyte plastids are thus serviced by three different genomes (plastid, nucleomorph, and host nucleus) requiring remarkable coordination and targeting. Although originating by two independent endosymbioses, chlorarachniophyte and cryptomonad nucleomorph genomes have converged upon remarkably similar architectures but differ in many molecular details that reflect two distinct trajectories to hypercompaction and reduction.

  4. Role of the hypothalamic arcuate nucleus in cardiovascular regulation.

    PubMed

    Sapru, Hreday N

    2013-04-01

    Recently the hypothalamic arcuate nucleus (Arc) has been implicated in cardiovascular regulation. Both pressor and depressor responses can be elicited by the chemical stimulation of the Arc. The direction of cardiovascular responses (increase or decrease) elicited from the Arc depends on the baseline blood pressure. The pressor responses are mediated via increase in sympathetic nerve activity and involve activation of the spinal ionotropic glutamate receptors. Arc-stimulation elicits tachycardic responses which are mediated via inhibition of vagal input and excitation of sympathetic input to the heart. The pathways within the brain mediating the pressor and tachycardic responses elicited from the Arc have not been delineated. The depressor responses to the Arc-stimulation are mediated via the hypothalamic paraventricular nucleus (PVN). Gamma aminobutyric acid type A receptors, neuropeptide Y1 receptors, and opiate receptors in the PVN mediate the depressor responses elicited from the Arc. Some circulating hormones (e.g., leptin and insulin) may reach the Arc via the leaky blood-brain barrier and elicit their cardiovascular effects. Although the Arc is involved in mediating the cardiovascular responses to intravenously injected angiotensin II and angiotensin-(1-12), these effects may not be due to leakage of these peptides across the blood-brain barrier in the Arc; instead, circulating angiotensins may act on neurons in the SFO and mediate cardiovascular actions via the projections of SFO neurons to the Arc. Cardiovascular responses elicited by acupuncture have been reported to be mediated by direct and indirect projections of the Arc to the RVLM. PMID:23260431

  5. NPY and VGF Immunoreactivity Increased in the Arcuate Nucleus, but Decreased in the Nucleus of the Tractus Solitarius, of Type-II Diabetic Patients

    PubMed Central

    Saderi, Nadia; Salgado-Delgado, Roberto; Avendaño-Pradel, Rafael; Basualdo, Maria del Carmen; Ferri, Gian-Luca; Chávez-Macías, Laura; Escobar, Carolina; Buijs, Ruud M.

    2012-01-01

    Ample animal studies demonstrate that neuropeptides NPY and α-MSH expressed in Arcuate Nucleus and Nucleus of the Tractus Solitarius, modulate glucose homeostasis and food intake. In contrast is the absence of data validating these observations for human disease. Here we compare the post mortem immunoreactivity of the metabolic neuropeptides NPY, αMSH and VGF in the infundibular nucleus, and brainstem of 11 type-2 diabetic and 11 non-diabetic individuals. α-MSH, NPY and tyrosine hydroxylase in human brain are localized in the same areas as in rodent brain. The similar distribution of NPY, α-MSH and VGF indicated that these neurons in the human brain may share similar functionality as in the rodent brain. The number of NPY and VGF immuno positive cells was increased in the infundibular nucleus of diabetic subjects in comparison to non-diabetic controls. In contrast, NPY and VGF were down regulated in the Nucleus of the Tractus Solitarius of diabetic patients. These results suggest an activation of NPY producing neurons in the arcuate nucleus, which, according to animal experimental studies, is related to a catabolic state and might be the basis for increased hepatic glucose production in type-2 diabetes. PMID:22808091

  6. NPY and VGF immunoreactivity increased in the arcuate nucleus, but decreased in the nucleus of the Tractus Solitarius, of type-II diabetic patients.

    PubMed

    Saderi, Nadia; Salgado-Delgado, Roberto; Avendaño-Pradel, Rafael; Basualdo, Maria del Carmen; Ferri, Gian-Luca; Chávez-Macías, Laura; Roblera, Juan E Olvera; Escobar, Carolina; Buijs, Ruud M

    2012-01-01

    Ample animal studies demonstrate that neuropeptides NPY and α-MSH expressed in Arcuate Nucleus and Nucleus of the Tractus Solitarius, modulate glucose homeostasis and food intake. In contrast is the absence of data validating these observations for human disease. Here we compare the post mortem immunoreactivity of the metabolic neuropeptides NPY, αMSH and VGF in the infundibular nucleus, and brainstem of 11 type-2 diabetic and 11 non-diabetic individuals. α-MSH, NPY and tyrosine hydroxylase in human brain are localized in the same areas as in rodent brain. The similar distribution of NPY, α-MSH and VGF indicated that these neurons in the human brain may share similar functionality as in the rodent brain. The number of NPY and VGF immuno positive cells was increased in the infundibular nucleus of diabetic subjects in comparison to non-diabetic controls. In contrast, NPY and VGF were down regulated in the Nucleus of the Tractus Solitarius of diabetic patients. These results suggest an activation of NPY producing neurons in the arcuate nucleus, which, according to animal experimental studies, is related to a catabolic state and might be the basis for increased hepatic glucose production in type-2 diabetes.

  7. Functional interactions between the nucleus tractus solitarius (NTS) and nucleus accumbens shell in modulating memory for arousing experiences.

    PubMed

    Kerfoot, Erin C; Chattillion, Elizabeth A; Williams, Cedric L

    2008-01-01

    The shell division of the nucleus accumbens receives noradrenergic input from neurons in the nucleus of the solitary tract (NTS) that transmit information regarding fluctuations in peripheral hormonal and autonomic activity. Accumbens shell neurons also receive converging inputs from limbic areas such as the hippocampus and amygdala that process newly acquired information. However, few studies have explored whether peripheral information regarding changes in emotional arousal contributes to memory processing in the accumbens. The beneficial effects on memory produced by emotional arousal and the corresponding activation of NTS neurons may be mediated through influences on neuronal activity in the accumbens shell during memory encoding. To explore this putative relationship, Experiment 1 examined interactions between the NTS and the accumbens shell in modulating memory for responses acquired after footshock training in a water-motivated inhibitory avoidance task. Memory for the noxious shock was significantly improved by posttraining excitation of noradrenergic NTS neurons. The enhanced retention produced by activating NTS neurons was attenuated by suppressing neuronal activity in the accumbens shell with bupivacaine (0.25%/0.5 microl). Experiment 2 examined the direct involvement of accumbens shell noradrenergic activation in the modulation of memory for psychologically arousing events such as a reduction in perceived reward value. Noradrenergic activation of the accumbens shell with phenylephrine (1.0 microg/0.5 microl) produced an enhancement in memory for the frustrating experience relative to control injections as evidenced by runway performance on an extended seven-day retention test. These findings demonstrate a functional relationship between NTS neurons and the accumbens shell in modulating memory following physiological arousal and identifies a role of norepinephrine in modulating synaptic activity in the accumbens shell to facilitate this process.

  8. Attributed relational graphs for cell nucleus segmentation in fluorescence microscopy images.

    PubMed

    Arslan, Salim; Ersahin, Tulin; Cetin-Atalay, Rengul; Gunduz-Demir, Cigdem

    2013-06-01

    More rapid and accurate high-throughput screening in molecular cellular biology research has become possible with the development of automated microscopy imaging, for which cell nucleus segmentation commonly constitutes the core step. Although several promising methods exist for segmenting the nuclei of monolayer isolated and less-confluent cells, it still remains an open problem to segment the nuclei of more-confluent cells, which tend to grow in overlayers. To address this problem, we propose a new model-based nucleus segmentation algorithm. This algorithm models how a human locates a nucleus by identifying the nucleus boundaries and piecing them together. In this algorithm, we define four types of primitives to represent nucleus boundaries at different orientations and construct an attributed relational graph on the primitives to represent their spatial relations. Then, we reduce the nucleus identification problem to finding predefined structural patterns in the constructed graph and also use the primitives in region growing to delineate the nucleus borders. Working with fluorescence microscopy images, our experiments demonstrate that the proposed algorithm identifies nuclei better than previous nucleus segmentation algorithms.

  9. Hoechst tagging: a modular strategy to design synthetic fluorescent probes for live-cell nucleus imaging.

    PubMed

    Nakamura, Akinobu; Takigawa, Kazumasa; Kurishita, Yasutaka; Kuwata, Keiko; Ishida, Manabu; Shimoda, Yasushi; Hamachi, Itaru; Tsukiji, Shinya

    2014-06-11

    We report a general strategy to create small-molecule fluorescent probes for the nucleus in living cells. Our strategy is based on the attachment of the DNA-binding Hoechst compound to a fluorophore of interest. Using this approach, simple fluorescein, BODIPY, and rhodamine dyes were readily converted to novel turn-on fluorescent nucleus-imaging probes.

  10. Redistribution of particles across the nucleus of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Thomas, N.; Davidsson, B.; El-Maarry, M. R.; Fornasier, S.; Giacomini, L.; Gracia-Berná, A. G.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Keller, H. U.; Knollenberg, J.; Kührt, E.; La Forgia, F.; Lai, I. L.; Liao, Y.; Marschall, R.; Massironi, M.; Mottola, S.; Pajola, M.; Poch, O.; Pommerol, A.; Preusker, F.; Scholten, F.; Su, C. C.; Wu, J. S.; Vincent, J.-B.; Sierks, H.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; Rickman, H.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Bertini, I.; Cremonese, G.; Da Deppo, V.; Debei, S.; de Cecco, M.; Fulle, M.; Groussin, O.; Gutierrez, P. J.; Kramm, J.-R.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Lopez Moreno, J. J.; Marzari, F.; Michalik, H.; Naletto, G.; Agarwal, J.; Güttler, C.; Oklay, N.; Tubiana, C.

    2015-11-01

    Context. We present an investigation of the surface properties of areas on the nucleus of comet 67P/Churyumov-Gerasimenko. Aims: We aim to show that transport of material from one part of the cometary nucleus to another is a significant mechanism that influences the appearance of the nucleus and the surface thermal properties. Methods: We used data from the OSIRIS imaging system onboard the Rosetta spacecraft to identify surface features on the nucleus that can be produced by various transport mechanisms. We used simple calculations based on previous works to establish the plausibility of dust transport from one part of the nucleus to another. Results: We show by observation and modeling that "airfall" as a consequence of non-escaping large particles emitted from the neck region of the nucleus is a plausible explanation for the smooth thin deposits in the northern hemisphere of the nucleus. The consequences are also discussed. We also present observations of aeolian ripples and ventifacts. We show by numerical modeling that a type of saltation is plausible even under the rarified gas densities seen at the surface of the nucleus. However, interparticle cohesive forces present difficulties for this model, and an alternative mechanism for the initiation of reptation and creep may result from the airfall mechanism. The requirements on gas density and other parameters of this alternative make it a more attractive explanation for the observations. The uncertainties and implications are discussed.

  11. Methods for the mineralogical and textural analysis of comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Stoeffler, D.; Dueren, H.; Knoelker, J.

    1989-01-01

    The objectives and instrumental requirements of a petrographic analysis of porous comet nucleus material are reviewed. Assumptions about its composition and texture, and the available techniques for the microscopic analysis of comet analogue material are investigated. New techniques required for the petrographic investigation of natural and artificial comet nucleus samples are also considered.

  12. Topography of the 81/P Wild 2 Nucleus Derived from Stardust Stereoimages

    NASA Technical Reports Server (NTRS)

    Kirk, R. L.; Duxbury, T. C.; Horz, F.; Brownlee, D. E.; Newburn, R. L.; Tsou, P.

    2005-01-01

    On 2 January, 2004, the Stardust spacecraft flew by the nucleus of comet 81P/Wild 2 with a closest approach distance of approx. 240 km. During the encounter, the Stardust Optical Navigation Camera (ONC) obtained 72 images of the nucleus with exposure times alternating between 10 ms (near-optimal for most of the nucleus surface) and 100 ms (used for navigation, and revealing additional details in the coma and dark portions of the surface. Phase angles varied from 72 deg. to near zero to 103 deg. during the encounter, allowing the entire sunlit portion of the surface to be imaged. As many as 20 of the images near closest approach are of sufficiently high resolution to be used in mapping the nucleus surface; of these, two pairs of short-exposure images were used to create the nucleus shape model and derived products reported here. The best image resolution obtained was approx. 14 m/pixel, resulting in approx. 300 pixels across the nucleus. The Stardust Wild 2 dataset is therefore markedly superior from a stereomapping perspective to the Deep Space 1 MICAS images of comet Borrelly. The key subset of the latter (3 images) covered only about a quarter of the surface at phase angles approx. 50 - 60 and less than 50 x 160 pixels across the nucleus, yet it sufficed for groups at the USGS and DLR to produce digital elevation models (DEMs) and study the morphology and photometry of the nucleus in detail.

  13. Formation of the dumbbell-like nucleus of a comet by sublimation

    NASA Astrophysics Data System (ADS)

    Vavilov, Dmitrii; Medvedev, Yurii; Zatitskiy, Pavel

    2016-10-01

    The nucleus of the comet 67P/Churyumov-Gerasimenko is an elongated body with a deep groove around the middle. There are also other comets that look like dumbbells (e.g. 103P/Hartley 2, 19P/Borrelly, 1P/Halley). Two most probable interpretations are discussed in the scientific society. The first hypothesis explains the creation of such an object as sticking of two cometesimals during the process of formation. The second one suggests that the sublimation process can change the nucleus shape and make a groove in the middle.In this work we consider the second hypothesis. It was assumed that the spin axis of the nucleus is perpendicular to the plane of the cometary orbit and that initially the nucleus shape is a sphere. Thus, the problem is represented as a differential equation, which describes the change of the cometary nucleus. We solved this equation analytically. It was shown that initially a convex cometary nucleus (e.g. a sphere), consisting of homogeneous material, can not be transformed into a dumbbell-like body by the influence of sublimation. However, assuming that the density in the centre of the nucleus is less than on the surface, a groove can arise on the equator of the cometary nucleus as a result of sublimation.

  14. Effects of cytotoxic nucleus accumbens lesions on instrumental conditioning in rats.

    PubMed

    de Borchgrave, R; Rawlins, J N P; Dickinson, A; Balleine, B W

    2002-05-01

    In two experiments the involvement of the nucleus accumbens in instrumental conditioning was investigated using rats as subjects. In experiment 1, extensive bilateral cytotoxic lesions of the nucleus accumbens mildly suppressed instrumental responding reinforced with food, but had no detectable effect on the sensitivity of the rats' performance either to outcome devaluation or to degradation of the instrumental contingency. In experiment 2, restricted accumbens lesions reliably attenuated the excitatory effect of systemically administered d-amphetamine on lever pressing for a conditioned reinforcer, and completely abolished Pavlovian-instrumental transfer. Taken together these results give a picture of the involvement of the rat nucleus accumbens in instrumental conditioning. They support the widely held theory that the nucleus accumbens mediates the excitatory effects of appetitively conditioned Pavlovian signals on instrumental performance and refute the hypothesis that the nucleus accumbens is part of the neural circuitry by which incentive value is attached to the representations of instrumental outcomes.

  15. Extended Glauber Model of Antiproton-Nucleus Annihilation for All Energies and Mass Numbers

    SciTech Connect

    Lee, Teck-Ghee; Wong, Cheuk-Yin

    2014-01-01

    Previous analytical formulas in the Glauber model for high-energy nucleus-nucleus collisions developed by Wong are utilized and extended to study Antiproton-nucleus annihilations for both high and low energies, after taking into account the effects of Coulomb and nuclear interactions, and the change of the antiproton momentum inside a nucleus. The extended analytical formulas capture the main features of the experimental antiproton-nucleus annihilation cross sections for all energies and mass numbers. At high antiproton energies, they exhibit the granular property for the lightest nuclei and the black-disk limit for the heavy nuclei. At low antiproton energies, they display the effect of the antiproton momentum increase due to the nuclear interaction for the light nuclei, and the effect of the magnification due to the attractive Coulomb interaction for the heavy nuclei.

  16. Compound-Nucleus Formation Following Direct Interactions to Highly-Excited Final States

    SciTech Connect

    Dietrich, F S

    2008-02-05

    When direct reactions populate highly excited, unbound configurations in the residual nucleus, the nucleus may further evolve into a compound nucleus. Alternatively, the residual system may decay by emitting particles into the continuum. Understanding the relative weights of these two processes as a function of the angular momentum and parity deposited in the nucleus is important for the surrogate-reaction technique. A particularly interesting case is compound-nucleus formation via the (d, p) reaction, which may be a useful tool for forming compound nuclei off the valley of stability in inverse-kinematics experiments. We present here a study of the compound formation probability for a closely-related direct reaction, direct-semidirect radiative neutron capture.

  17. Synaptic endfeet in the 'acoustic nerve nucleus' of the rat. An electron microscopic study.

    PubMed Central

    Alvarez-Bolado, G; Merchán, J

    1988-01-01

    The medial portion of the cochlear nerve of the rat contains astrocytes, oligodendrocytes and neurons. These neurons form what has been called the 'acoustic nerve nucleus'. This nucleus has been studied here at the electron microscopic level. Its neurons are large and round, showing an eccentric nucleus, fibrillary bodies and rough endoplasmic reticulum which is not arranged in stacks. The somata and dendrites receive synaptic endfeet which can be classified into three groups according to vesicle size and shape. In general, the ultrastructural characteristics of these cells are similar to those of bushy cells as reported by other authors. The 'acoustic nerve nucleus' can be considered to be the most peripheral part of the anterior ventral cochlear nucleus. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 PMID:3248967

  18. A light and electron microscope study of rat abducens nucleus neurons projecting to the cerebellar flocculus.

    PubMed Central

    Rodella, L; Rezzani, R; Corsetti, G; Simonetti, C; Stacchiotti, A; Ventura, R G

    1995-01-01

    Injection of horseradish peroxidase (HRP) into the cerebellar flocculus of the rat was employed to identify neurons in the abducens nucleus that project to the flocculus. The number, ultrastructural features and precise localisation of these neurons in the nucleus were examined. They were present bilaterally and represented about 7% of the total neuronal population of each nucleus. They were localised principally in the dorsomedial area of the cranial half of each nucleus and did not display the typical ultrastructural features of motoneurons. It is concluded that the localisation and ultrastructural characteristics of these HRP-positive neurons are useful for distinguishing them from other neuronal populations within the nucleus. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 PMID:7649835

  19. Visual discrimination in the pigeon (Columba livia): effects of selective lesions of the nucleus rotundus

    NASA Technical Reports Server (NTRS)

    Laverghetta, A. V.; Shimizu, T.

    1999-01-01

    The nucleus rotundus is a large thalamic nucleus in birds and plays a critical role in many visual discrimination tasks. In order to test the hypothesis that there are functionally distinct subdivisions in the nucleus rotundus, effects of selective lesions of the nucleus were studied in pigeons. The birds were trained to discriminate between different types of stationary objects and between different directions of moving objects. Multiple regression analyses revealed that lesions in the anterior, but not posterior, division caused deficits in discrimination of small stationary stimuli. Lesions in neither the anterior nor posterior divisions predicted effects in discrimination of moving stimuli. These results are consistent with a prediction led from the hypothesis that the nucleus is composed of functional subdivisions.

  20. Planar multipolar cells in the cochlear nucleus project to medial olivocochlear neurons in mouse.

    PubMed

    Darrow, Keith N; Benson, Thane E; Brown, M Christian

    2012-05-01

    Medial olivocochlear (MOC) neurons originate in the superior olivary complex and project to the cochlea, where they act to reduce the effects of noise masking and protect the cochlea from damage. MOC neurons respond to sound via a reflex pathway; however, in this pathway the cochlear nucleus cell type that provides input to MOC neurons is not known. We investigated whether multipolar cells of the ventral cochlear nucleus have projections to MOC neurons by labeling them with injections into the dorsal cochlear nucleus. The projections of one type of labeled multipolar cell, planar neurons, were traced into the ventral nucleus of the trapezoid body, where they were observed terminating on MOC neurons (labeled in some cases by a second cochlear injection of FluoroGold). These terminations formed what appear to be excitatory synapses, i.e., containing small, round vesicles and prominent postsynaptic densities. These data suggest that cochlear nucleus planar multipolar neurons drive the MOC neuron's response to sound.

  1. GABAergic Projections to the Oculomotor Nucleus in the Goldfish (carassius Auratus)

    PubMed Central

    Luque, M. Angeles; Torres-Torrelo, Julio; Carrascal, Livia; Torres, Blas; Herrero, Luis

    2010-01-01

    The mammalian oculomotor nucleus receives a strong γ-aminobutyric acid (GABA)ergic synaptic input, whereas such projections have rarely been reported in fish. In order to determine whether this synaptic organization is preserved across vertebrates, we investigated the GABAergic projections to the oculomotor nucleus in the goldfish by combining retrograde transport of biotin dextran amine, injected into the antidromically identified oculomotor nucleus, and GABA immunohistochemistry. The main source of GABAergic afferents to the oculomotor nucleus was the ipsilateral anterior octaval nucleus, with only a few, if any, GABAergic neurons being located in the contralateral tangential and descending nuclei of the octaval column. In mammals there is a nearly GABAergic inhibitory inputs; thus, the vestibulooculomotor GABAergic circuitry follows a plan that appears to be shared throughout the vertebrate phylogeny. The second major source of GABAergic projections was the rhombencephalic reticular formation, primarily from the medial area but, to a lesser extent, from the inferior area. A few GABAergic oculomotor projecting neurons were also observed in the ipsilateral nucleus of the medial longitudinal fasciculus. The GABAergic projections from neurons located in both the reticular formation surrounding the abducens nucleus and the nucleus of the medial reticular formation have primarily been related to the control of saccadic eye movements. Finally, all retrogradely labeled internuclear neurons of the abducens nucleus, and neurons in the cerebellum (close to the caudal lobe), were negative for GABA. These data suggest that the vestibuloocular and saccadic inhibitory GABAergic systems appear early in vertebrate phylogeny to modulate the firing properties of the oculomotor nucleus motoneurons. PMID:21331170

  2. The Foxb1-expressing neurons of the ventrolateral hypothalamic parvafox nucleus project to defensive circuits.

    PubMed

    Bilella, Alessandro; Alvarez-Bolado, Gonzalo; Celio, Marco R

    2016-10-15

    The parvafox nucleus is an elongated structure that is lodged within the ventrolateral hypothalamus and lies along the optic tract. It comprises axially located parvalbumin (Parv)-positive neurons and a peripheral cuff of Foxb1-expressing ones. In the present study, injections of Cre-dependent adenoviral constructs were targeted to the ventrolateral hypothalamus of Foxb1/Cre mice to label specifically and map the efferent connections of the Foxb1-expressing subpopulation of neurons of the parvafox nucleus. These neurons project more widely than do the Parv-positive ones and implicate a part of the axons known to emanate from the lateral hypothalamus. High labeling densities were found in the dorsolateral and the upper lateral portion of the periaqueductal gray (PAG), the Su3 and PV2 nuclei of the ventrolateral PAG, the cuneiform nucleus, the mesencephalic reticular formation, and the superior colliculus. Intermediate densities of terminals were encountered in the septum, bed nucleus of the stria terminalis, substantia innominata, various thalamic and hypothalamic nuclei, pedunculopontine nucleus, Barrington's nucleus, retrofacial nucleus, and retroambigual nucleus. Scattered terminals were observed in the olfactory bulbs, the prefrontal cortex and the lamina X of the cervical spinal cord. Because the terminals were demonstrated to express the glutamate transporter VGlut2, the projections are presumed to be excitatory. A common denominator of the main target sites of the Foxb1-positive axons of the parvafox nucleus appears to be an involvement in the defensive reactions to life-threatening situations. The hypothalamic parvafox nucleus may contribute to the autonomic manifestations that accompany the expression of emotions. J. Comp. Neurol. 524:2955-2981, 2016. © 2016 Wiley Periodicals, Inc. PMID:27292133

  3. The Foxb1-expressing neurons of the ventrolateral hypothalamic parvafox nucleus project to defensive circuits.

    PubMed

    Bilella, Alessandro; Alvarez-Bolado, Gonzalo; Celio, Marco R

    2016-10-15

    The parvafox nucleus is an elongated structure that is lodged within the ventrolateral hypothalamus and lies along the optic tract. It comprises axially located parvalbumin (Parv)-positive neurons and a peripheral cuff of Foxb1-expressing ones. In the present study, injections of Cre-dependent adenoviral constructs were targeted to the ventrolateral hypothalamus of Foxb1/Cre mice to label specifically and map the efferent connections of the Foxb1-expressing subpopulation of neurons of the parvafox nucleus. These neurons project more widely than do the Parv-positive ones and implicate a part of the axons known to emanate from the lateral hypothalamus. High labeling densities were found in the dorsolateral and the upper lateral portion of the periaqueductal gray (PAG), the Su3 and PV2 nuclei of the ventrolateral PAG, the cuneiform nucleus, the mesencephalic reticular formation, and the superior colliculus. Intermediate densities of terminals were encountered in the septum, bed nucleus of the stria terminalis, substantia innominata, various thalamic and hypothalamic nuclei, pedunculopontine nucleus, Barrington's nucleus, retrofacial nucleus, and retroambigual nucleus. Scattered terminals were observed in the olfactory bulbs, the prefrontal cortex and the lamina X of the cervical spinal cord. Because the terminals were demonstrated to express the glutamate transporter VGlut2, the projections are presumed to be excitatory. A common denominator of the main target sites of the Foxb1-positive axons of the parvafox nucleus appears to be an involvement in the defensive reactions to life-threatening situations. The hypothalamic parvafox nucleus may contribute to the autonomic manifestations that accompany the expression of emotions. J. Comp. Neurol. 524:2955-2981, 2016. © 2016 Wiley Periodicals, Inc.

  4. Human Disc Nucleus Properties and Vertebral Endplate Permeability

    PubMed Central

    Rodriguez, Azucena G.; Slichter, Chloe K.; Acosta, Frank L.; Rodriguez-Soto, Ana E.; Burghardt, Andrew J.; Majumdar, Sharmila; Lotz, Jeffrey C.

    2010-01-01

    Study of human cadaveric discs quantifying endplate permeability and porosity and correlating these with measures of disc quality: cell density, proteoglycan content, and overall degeneration. Permeability and porosity increased with age and were not correlated with cell density or overall degeneration, suggesting that endplate calcification may not accelerate disc degeneration. Study Design Experimental quantification of relationships between vertebral endplate morphology, permeability, disc cell density, glycosaminoglycan content and degeneration in samples harvested from human cadaveric spines. Objective To test the hypothesis that variation in endplate permeability and porosity contribute to changes in intervertebral disc cell density and overall degeneration. Summary of Background Data Cells within the intervertebral disc are dependent on diffusive exchange with capillaries in the adjacent vertebral bone. Previous findings suggest that blocked routes of transport negatively affect disc quality, yet there are no quantitative relationships between human vertebral endplate permeability, porosity, cell density and disc degeneration. Such relationships would be valuable for clarifying degeneration risk factors, and patient features that may impede efforts at disc tissue engineering. Methods Fifty-one motion segments were harvested from 13 frozen cadaveric human lumbar spines (32 to 85 years) and classified for degeneration using the MRI-based Pfirrmann scale. A cylindrical core was harvested from the center of each motion segment that included vertebral bony and cartilage endplates along with adjacent nucleus tissue. The endplate mobility, a type of permeability, was measured directly using a custom-made permeameter before and after the cartilage endplate was removed. Cell density within the nucleus tissue was estimated using the picogreen method while the nuclear GAG content was quantified using the DMMB technique. Specimens were imaged at 8 μm resolution using

  5. Conversion electron spectroscopy at the FMA focal plane: Decay studies of proton-rich N {approximately} 82 nuclei

    SciTech Connect

    Nisius, D.; Janssens, R.V.F.; Ahmad, I.

    1995-08-01

    The FMA has proven to be an ideal instrument for the detailed study of the decay of microsecond isomers behind the focal plane following mass selection. In reactions leading to the population of nuclei with isomeric lifetimes longer than their flight time through the device, decay gamma rays and conversion electrons can be detected in an environment free from the backgrounds of prompt radiation and delta electrons. This was a very successful technique to study proton (h{sub 11/2}){sup n} seniority isomers in nuclei with Z > 64 and N {approximately} 82. Since isomeric decay gamma rays are emitted isotropically, conversion electrons are essential for the assignment of multipolarities in these nuclei. Furthermore, the low-energy transitions that depopulate isomeric states are typically highly converted and can escape gamma-ray detection, but they can be identified by their conversion electrons.

  6. Beta Decay of the Proton-Rich Nuclei 102Sn and 104Sn

    SciTech Connect

    Karny, M.; Batist, L.; Banu, A.; Becker, F.; Blazhev, A.; Brown, B. A.; Bruchle, W.; Doring, J.; Faestermann, T.; Gorska, M.; Grawe, H.; Janas, Z.; Jungclaus, A.; Kavatsyuk, M.; Kavatsyuk, O.; Kirchner, R.; La Commara, M.; Mandal, S.; Mazzocchi, C.; Miernik, K.; Mukha, I.; Muralithar, S.; Plettner, C.; Plochocki, A.; Roeckl, E.; Romoli, M.; Rykaczewski, Krzysztof Piotr; Schadel, M.; Schmidt, K.; Schwengner, R.; Zylicz, J.

    2006-01-01

    The {beta} decays of {sup 102}Sn and {sup 104}Sn were studied by using high-resolution germanium detectors as well as a Total Absorption Spectrometer (TAS). For {sup 104}Sn, with three new {beta}-delayed {gamma}-rays identified, the total Gamow-Teller strength (BGT) value of 2.7(3) was obtained. For {sup 102}Sn, the {gamma}-{gamma} coincidence data were collected for the first time, allowing us to considerably extend the decay scheme. This scheme was used to unfold the TAS data and to deduce a BGT value of 4.2(8) for this decay. This result is compared to shell model predictions, yielding a hindrance factor of 3.6(7) in agreement with those obtained previously for {sup 98}Cd and {sup 100}In. Together with the latter two, {sup 102}Sn completes the triplet of Z {le} 50, N {ge} 50 nuclei with two proton holes, one proton hole and one neutron particle, and two neutron particles with respect to the doubly magic {sup 100}Sn core.

  7. Are Quasars Ejected from the Nucleus of NGC 4258?

    NASA Astrophysics Data System (ADS)

    Kondratko, P. T.; Greenhill, L. J.; Moran, J. M.

    2001-12-01

    The H2O maser in NGC 4258 traces a thin, almost edge-on, and slightly warped molecular disk around a supermassive black hole. Extensive measurements of the positions, three dimensional velocity vectors, and accelerations of dozens of masers are well explained by a simple disk model. However, discovery of two quasars with redshifts 0.39 and 0.65 symmetrically displaced by ~ 9' from the nucleus of NGC 4258 and located approximately at the position angle of the maser disk has fueled an alternative hypothesis by G. Burbidge, E.M. Burbidge, and co-workers. They proposed that the two quasars were ejected from the nucleus, are dynamically associated with the maser, and possess redshifts which are primarily non-cosmological in origin. We use 3 epochs of 20 cm VLBA images of one of the quasars and of NGC 4258 to derive an upper limit on the quasar proper motion of 0.4 mas year-1 (0.05 c) in the putative direction of ejection and with respect to the continuum emission from NGC 4258. This upper limit excludes the Ozernoy model in which the redshifts of the two quasars are primarily due to the transverse Doppler effect caused by a tranverse velocity of 6.6 mas year-1 (0.75 c). In addition to fixing an upper limit on the quasar proper motion, the images of NGC 4258 jet reveal a dominant, apparently stationary component located approximately ~ 6 mas north from the black hole and corresponding to the northern core of the jet. The distance of the core from the black hole scales with λ as expected in the standard model of Blandford and Königl. The southern jet core is undetected perhaps due to high optical depth associated with a hot, ionized wind or with an ionized material in the disk. The jet in the immediate vicinity of the central engine is characterized by γ >4.3, which appears to be relatively stable over time.

  8. Activity in the caudate nucleus of monkey during spatial sequencing.

    PubMed

    Kermadi, I; Joseph, J P

    1995-09-01

    1. There are indications that the execution of behavioral sequences involves the basal ganglia. In this study we examined the role of the caudate nucleus in the construction, storage, and execution of spatial plans. 2. Two monkeys (Macaca mulatta) were trained to perform sequences of saccades and arm movements. The animals had to remember the order of illumination, variable from one sequence to another, of three fixed spatial targets. After a delay, they had to visually orient toward, and press each target in the same order. Six different sequences were executed on the basis of the order of illumination of the targets. Single cell activity was recorded from the four caudate nuclei of the two monkeys. 3. Neural activity was analyzed in each sequence during 10 different periods: the instruction period in which the targets were illuminated, the three orientation periods toward the different targets, the three postsaccadic periods, and the three periods of target pressing. Statistical comparisons were made to detect differences between the different sequences with respect to activity in each period (sequence specificity). 4. A total of 2,100 neurons were studied, of which 387 were task related. The task-related cells were found in both the head and the body of the caudate nucleus. 5. During central fixation, anticipatory activity (n = 81) preceded onset of specific events. Four groups were considered: 1) neurons (n = 46) anticipating offset of the central fixation point, 2) neurons (n = 7) anticipating the illumination of any target, regardless of its spatial position or order of presentation (rank), 3) neurons (n = 17) anticipating the illumination of the first target, regardless of its spatial position, and 4) neurons (n = 11) anticipating the illumination of a given target, regardless of its rank. 6. Phasic visual responses to target onset were observed in 48 cells. The cells responded primarily to the contralateral and upper targets. In a majority (n = 35), visual

  9. The primordial nucleus of Comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Davidsson, Bjorn; Sierks, Holger; Guettler, Carsten; Marzari, Francesco; Pajola, Maurizio; Rickman, Hans; A'Hearn, Michael; Auger, Anne-Therese; El-Maarry, Mohamed; Fornasier, Sonia; Gutierrez, Pedro; Keller, Horst Uwe; Massironi, Matteo; Snodgrass, Colin; Vincent, Jean-Baptiste; Barbieri, Cesare; Lamy, Philippe; Rodrigo, Rafael; Koschny, Detlef; Barucci, Antonella; Bertaux, Jean-Loup; Bertini, Ivano; Cremonese, Gabriele; Da Deppo, Vania; Debei, Stefano; De Cecco, Mariolino; Feller, Clement; Fulle, Marco; Groussin, Olivier; Hviid, Stubbe; Hoefner, Sebastian; Ip, Wing-Huen; Jorda, Laurent; Knollenberg, Joerg; Kovacs, Gabor; Kramm, Joerg-Rainer; Kuehrt, Ekkehard; Kueppers, Michael; La Forgia, Fiorangela; Lara, Luisa; Lazzarin, Monica; Lopez Moreno, Jose; Moissl-Fraund, Richard; Mottola, Stefano; Naletto, Giampiero; Oklay, Nilda; Thomas, Nicolas; Tubiana, Cecilia

    2015-11-01

    Observations of Comet 67P/Churyumov-Gerasimenko by Rosetta show that the nucleus is bi-lobed, extensively layered, has a low bulk density, a high dust-to-ice mass ratio (implying high porosity), and weak strength except for a thin sintered surface layer. The comet is rich in supervolatiles (CO, CO2, N2), may contain amorphous water ice, and displays little to no signs of aqueous alteration. Lack of phyllosilicates in Stardust samples from Comet 81P/Wild 2 provides further support that comet nuclei did not contain liquid water.These properties differ from those expected for 50-200 km diameter bodies in the primordial disk. We find that thermal processing due to Al-26, combined with collisional compaction, creates a population of medium-sized bodies that are comparably dense, compacted, strong, heavily depleted in supervolatiles, containing little to no amorphous water ice, and that have experienced extensive aqueous alteration. Irregular satellites Phoebe and Himalia are potential representatives of this population. Collisional rubble piles inherit these properties from their parents. We therefore conclude that observed comet nuclei are primordial rubble piles, and not collisional rubble piles.We propose a concurrent comet and TNO formation scenario that is consistent with these observations. We argue that TNOs form due to streaming instabilities at sizes of about 50-400 km and that about 350 of these grow slowly in a low-mass primordial disk to the size of Triton, causing little viscous stirring during growth. We propose a dynamically cold primordial disk, that prevents medium-sized TNOs from breaking into collisional rubble piles, and allows for the survival of primordial rubble-pile comets. We argue that comets form by hierarchical agglomeration out of material that remains after TNO formation. This slow growth is necessary to avoid thermal processing by Al-26, and to allow comet nuclei to incorporate 3 Myr old material from the inner Solar System, found in

  10. TNRT profiles with the nucleus research platform 8 system.

    PubMed

    Lai, W K; Dillier, N; Weber, B P; Lenarz, T; Battmer, R; Gantz, B; Brown, C; Cohen, N; Waltzman, S; Skinner, M; Holden, L; Cowan, R; Busby, P; Killian, M

    2009-01-01

    This study investigates the effect of the Nucleus CI24RE implant's neural response telemetry (NRT) system, which has less internal noise compared to its predecessor, the CI24M/R implant, on the NRT threshold (TNRT) profile across the array. CI24M/R measurements were simulated by ignoring CI24RE measurements with response amplitudes below 50 uV. Comparisons of the estimated TNRTs from the CI24RE measurements and the CI24M/R simulations suggest that, apart from a constant level difference, the TNRT profiles from the newer implant generally would not have differed very much from those of its predecessor. This view was also reflected by principal component analysis (PCA) results which revealed a 'shift' component similar to that reported by Smoorenburg et al (2002). On the whole, there is no indication that current practices of using the TNRT profiles for assisting with speech processor programming need to be revised for the CI24RE implant. PMID:19513917

  11. GABAergic processes within the median preoptic nucleus promote NREM sleep.

    PubMed

    Benedetto, Luciana; Chase, Michael H; Torterolo, Pablo

    2012-06-15

    GABAergic mechanisms in the preoptic region of the hypothalamus (POA) have been implicated in the generation and maintenance of NREM (quiet) sleep. We recently reported that neurons in the median peptic nucleus (MnPN) in the POA of the cat are selectively activated during NREM sleep. In the present study, we explored the hypothesis that NREM sleep is controlled by GABAergic mechanisms within the MnPN. Consequently, adult cats were utilized to determine GABA immunorreactivity within the MnPN and to examine the effects on sleep of the microinjection of a GABA(A) agonist (muscimol) and a GABA(A) antagonist (bicuculline) into this area. GABAergic neurons were present throughout the MnPN. Compared with control microinjections, after the application of muscimol, the time spent in NREM sleep (59.8±7.5 min) and REM sleep (6.9±4.7 min) decreased compared with control microinjections (103.8±5.2 and 20.2±4.3 min, respectively; P<0.005). In contrast, bicuculline microinjections increased only NREM sleep time (103.0±23.0 vs 77.7±23.7 min; P<0.05). These results demonstrate that GABAergic processes within the MnPN are involved in the generation and maintenance of sleep, especially NREM sleep. PMID:22483998

  12. Recording Gamma Band Oscillations in Pedunculopontine Nucleus Neurons.

    PubMed

    Urbano, Francisco J; Luster, Brennon R; D'Onofrio, Stasia; Mahaffey, Susan; Garcia-Rill, Edgar

    2016-01-01

    Synaptic efferents from the PPN are known to modulate the neuronal activity of several intralaminar thalamic regions (e.g., the centrolateral/parafascicular; Cl/Pf nucleus). The activation of either the PPN or Cl/Pf nuclei in vivo has been described to induce the arousal of the animal and an increment in gamma band activity in the cortical electroencephalogram (EEG). The cellular mechanisms for the generation of gamma band oscillations in Reticular Activating System (RAS) neurons are the same as those found to generate gamma band oscillations in other brains nuclei. During current-clamp recordings of PPN neurons (from parasagittal slices from 9 - 25 day-old rats), the use of depolarizing square steps rapidly activated voltage-dependent potassium channels that prevented PPN neurons from being depolarized beyond -25 mV. Injecting 1 - 2 sec long depolarizing current ramps gradually depolarized PPN membrane potential resting values towards 0 mV. However, injecting depolarizing square pulses generated gamma-band oscillations of membrane potential that showed to be smaller in amplitude compared to the oscillations generated by ramps. All experiments were performed in the presence of voltage-gated sodium channels and fast synaptic receptors blockers. It has been shown that the activation of high-threshold voltage-dependent calcium channels underlie gamma-band oscillatory activity in PPN neurons. Specific methodological and pharmacological interventions are described here, providing the necessary tools to induce and sustain PPN subthreshold gamma band oscillation in vitro. PMID:27684729

  13. Morphological differences in the lateral geniculate nucleus associated with dyslexia.

    PubMed

    Giraldo-Chica, Mónica; Hegarty, John P; Schneider, Keith A

    2015-01-01

    Developmental dyslexia is a common learning disability characterized by normal intelligence but difficulty in skills associated with reading, writing and spelling. One of the most prominent, albeit controversial, theories of dyslexia is the magnocellular theory, which suggests that malfunction of the magnocellular system in the brain is responsible for the behavioral deficits. We sought to test the basis of this theory by directly measuring the lateral geniculate nucleus (LGN), the only location in the brain where the magnocellular and parvocellular streams are spatially disjoint. Using high-resolution proton-density weighted MRI scans, we precisely measured the anatomical boundaries of the LGN in 13 subjects with dyslexia (five female) and 13 controls (three female), all 22-26 years old. The left LGN was significantly smaller in volume in subjects with dyslexia and also differed in shape; no differences were observed in the right LGN. The functional significance of this asymmetry is unknown, but these results are consistent with the magnocellular theory and support theories of dyslexia that involve differences in the early visual system.

  14. Hyperdipsia in rats after electrolytic lesions of nucleus medianus.

    PubMed

    Gardiner, T W; Stricker, E M

    1985-02-01

    Ablation of the ventral portion of nucleus medianus (vNM) in rats produced a temporary adipsia or hypodipsia that was accompanied by pronounced urinary fluid losses. When ad libitum drinking resumed, about half of the brain-damaged animals became hyperdipsic, exhibiting chronic two- to threefold elevations in their daily water intakes during the nocturnal hours of the day-night cycle. Rats that remained normodipsic after vNM ablation usually exhibited hyperdipsia if they were food-deprived overnight. The basis for the hyperdipsia produced by vNM ablation was not clear. The elevated water intakes appeared not to result from chronic urinary fluid losses, because hyperdipsic rats were able to concentrate their urine during the day, when they drank little. Moreover, the animals did not seem to be volume depleted; their plasma renin activities were not elevated, and they drank normally in association with meals. These and other findings suggest that vNM lesions damage neural substrates that control drinking behavior, and the hyperdipsia results from this rather than from physiological changes produced by the lesion.

  15. In vivo selection of RNAs that localize in the nucleus.

    PubMed Central

    Grimm, C; Lund, E; Dahlberg, J E

    1997-01-01

    Nuclear localization of an RNA is affected by cis-acting elements (NLEs) that lead to nuclear import or retention or to blockage of export from the nucleus. To identify such elements, we selected and analyzed transcripts that localized in the nuclei of Xenopus laevis oocytes. The RNAs were isolated from a collection of m7G-capped RNAs in which a combinatorial library (n = 20) of sequences had been inserted. One class of selected RNAs (Sm+) had a consensus Sm binding site (AAUUUUUGG) and bound Sm proteins in the cytoplasm; these RNAs resembled small nuclear RNAs like U1 and U5 RNAs in their bi-directional nucleocytoplasmic transport and their 5'-cap hypermethylation. Another class, Sm- RNAs, contained sequences that masked the m7G-caps of the RNAs and promoted interaction with La protein. These RNAs were retained within nuclei after nuclear injection and were imported when injected into the cytoplasm. Their nuclear import and retention were independent of a 5'-cap, required an imperfect double-stranded stem near the 5' end, and depended on interaction with La protein. Import of the Sm- RNAs, while using the import pathway of proteins, was distinct from that of U6 RNA. PMID:9049308

  16. Light-dark cycle memory in the mammalian suprachiasmatic nucleus.

    PubMed

    Ospeck, Mark C; Coffey, Ben; Freeman, Dave

    2009-09-16

    The mammalian circadian oscillator, or suprachiasmatic nucleus (SCN), contains several thousand clock neurons in its ventrolateral division, many of which are spontaneous oscillators with period lengths that range from 22 to 28 h. In complete darkness, this network synchronizes through the exchange of action potentials that release vasoactive intestinal polypeptide, striking a compromise, free-running period close to 24 h long. We entrained Siberian hamsters to various light-dark cycles and then tracked their activity into constant darkness to show that they retain a memory of the previous light-dark cycle before returning to their own free-running period. Employing Leloup-Goldbeter mammalian clock neurons we model the ventrolateral SCN network and show that light acting weakly upon a strongly rhythmic vasoactive intestinal polypeptide oscillation can explain the observed light-dark cycle memory. In addition, light is known to initiate a mitogen-activated protein kinase signaling cascade that induces transcription of both per and mkp1 phosphatase. We show that the ensuing phosphatase-kinase interaction can account for the dead zone in the mammalian phase response curve and hypothesize that the SCN behaves like a lock-in amplifier to entrain to the light edges of the circadian day.

  17. Cortically evoked potentials in the human subthalamic nucleus.

    PubMed

    Zwartjes, Daphne G M; Janssen, Marcus L F; Heida, Tjitske; Van Kranen-Mastenbroek, Vivianne; Bour, Lo J; Temel, Yasin; Visser-Vandewalle, Veerle; Veltink, Peter H

    2013-02-28

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates motor symptoms in Parkinson's disease (PD) patients. However, in a substantial number of patients the beneficial effects of STN DBS are overshadowed by psychiatric side effects. We hypothesize that stimulation of the STN motor area will provide the optimal effect on the motor symptoms without inducing these side effects, and expect that motor cortex stimulation (MCS) evokes a spatially specific response within the STN, which identifies the STN motor area. We previously showed that MCS evokes responses in the unit activity specifically within certain areas of the STN. Unit activity is generally considered a measure of the output activity. To gain more insight into the neuronal input into the STN, we describe the results of cortically evoked subthalamic local field potentials (LFPs). We show that the cortically evoked LFPs follow a certain temporal and spatial pattern. The significant peaks of the evoked LFPs coincide with the timing of some of the inhibitions and excitations present in the unit responses. The spatial resolution of responses measured in the LFP to MCS is not high enough to identify the STN motor region. However, we believe that optimizing targeting techniques and the development of novel DBS electrodes will improve STN DBS therapy for PD patients.

  18. ATG5: a distinct role in the nucleus.

    PubMed

    Simon, Hans-Uwe; Friis, Robert

    2014-01-01

    Both apoptotic and autophagic pathways are activated in cells during anticancer treatment using DNA-damaging agents. Thus, the outcome is balanced between apoptotic cell death and enhanced autophagy, with the possibility of prolonged cell survival. It seems intuitively obvious that this survival mechanism might interfere with the desired tumor cell killing. We addressed this question by tipping the balance in favor of autophagy, using etoposide or cisplatin at low, sublethal doses. Over 4 days, only a little apoptosis was observed, but both drugs sharply increased autophagic flux. Surprisingly, cells underwent a cell cycle arrest at G 2/M, followed later by mitotic catastrophe with formation of multipolar spindles, missegregated chromosomes, or enlarged, irregular, sometimes multiple nuclei. Why? The answer is that even a low level of DNA damage not only upregulates autophagy, but also provokes the recruitment of an autophagy-related protein, ATG5, to the nucleus, where it binds BIRC5/survivin, thereby interfering with correct assembly of the chromosome passenger complex needed for cytokinesis.

  19. ELAV proteins along evolution: back to the nucleus?

    PubMed

    Colombrita, Claudia; Silani, Vincenzo; Ratti, Antonia

    2013-09-01

    The complex interplay of post-transcriptional regulatory mechanisms mediated by RNA-binding proteins (RBP) at different steps of RNA metabolism is pivotal for the development of the nervous system and the maintenance of adult brain activities. In this review, we will focus on the highly conserved ELAV gene family encoding for neuronal-specific RBPs which are necessary for proper neuronal differentiation and important for synaptic plasticity process. In the evolution from Drosophila to man, ELAV proteins seem to have changed their biological functions in relation to their different subcellular localization. While in Drosophila, they are localized in the nuclear compartment of neuronal cells and regulate splicing and polyadenylation, in mammals, the neuronal ELAV proteins are mainly present in the cytoplasm where they participate in regulating mRNA target stability, translation and transport into neurites. However, recent data indicate that the mammalian ELAV RBPs also have nuclear activities, similarly to their fly counterpart, being them able to continuously shuttle between the cytoplasm and the nucleus. Here, we will review and comment on all the biological functions associated with neuronal ELAV proteins along evolution and will show that the post-transcriptional regulatory network mediated by these RBPs in the brain is highly complex and only at an initial stage of being fully understood. This article is part of a Special Issue entitled 'RNA and splicing regulation in neurodegeneration'.

  20. Developmental changes in synaptic distribution in arcuate nucleus neurons.

    PubMed

    Baquero, Arian F; Kirigiti, Melissa A; Baquero, Karalee C; Lee, Shin J; Smith, M Susan; Grove, Kevin L

    2015-06-01

    Neurons coexpressing neuropeptide Y, agouti-related peptide, and GABA (NAG) play an important role in ingestive behavior and are located in the arcuate nucleus of the hypothalamus. NAG neurons receive both GABAergic and glutamatergic synaptic inputs, however, the developmental time course of synaptic input organization of NAG neurons in mice is unknown. In this study, we show that these neurons have low numbers of GABAergic synapses and that GABA is inhibitory to NAG neurons during early postnatal period. In contrast, glutamatergic inputs onto NAG neurons are relatively abundant by P13 and are comparatively similar to the levels observed in the adult. As mice reach adulthood (9-10 weeks), GABAergic tone onto NAG neurons increases. At this age, NAG neurons received similar numbers of inhibitory and EPSCs. To further differentiate age-associated changes in synaptic distribution, 17- to 18-week-old lean and diet-induced obesity (DIO) mice were studied. Surprisingly, NAG neurons from lean adult mice exhibit a reduction in the GABAergic synapses compared with younger adults. Conversely, DIO mice display reductions in the number of GABAergic and glutamatergic inputs onto NAG neurons. Based on these experiments, we propose that synaptic distribution in NAG neurons is continuously restructuring throughout development to accommodate the animals' energy requirements.

  1. On Parallel Streams through the Mouse Dorsal Lateral Geniculate Nucleus.

    PubMed

    Denman, Daniel J; Contreras, Diego

    2016-01-01

    The mouse visual system is an emerging model for the study of cortical and thalamic circuit function. To maximize the usefulness of this model system, it is important to analyze the similarities and differences between the organization of all levels of the murid visual system with other, better studied systems (e.g., non-human primates and the domestic cat). While the understanding of mouse retina and cortex has expanded rapidly, less is known about mouse dorsal lateral geniculate nucleus (dLGN). Here, we study whether parallel processing streams exist in mouse dLGN. We use a battery of stimuli that have been previously shown to successfully distinguish parallel streams in other species: electrical stimulation of the optic chiasm, contrast-reversing stationary gratings at varying spatial phase, drifting sinusoidal gratings, dense noise for receptive field reconstruction, and frozen contrast-modulating noise. As in the optic nerves of domestic cats and non-human primates, we find evidence for multiple conduction velocity groups after optic chiasm stimulation. As in so-called "visual mammals", we find a subpopulation of mouse dLGN cells showing non-linear spatial summation. However, differences in stimulus selectivity and sensitivity do not provide sufficient basis for identification of clearly distinct classes of relay cells. Nevertheless, consistent with presumptively homologous status of dLGNs of all mammals, there are substantial similarities between response properties of mouse dLGN neurons and those of cats and primates.

  2. Consolidation of altered associability information by amygdala central nucleus.

    PubMed

    Schiffino, Felipe L; Holland, Peter C

    2016-09-01

    The surprising omission of a reinforcer can enhance the associability of the stimuli that were present when the reward prediction error was induced, so that they more readily enter into new associations in the future. Previous research from this laboratory identified brain circuit elements critical to the enhancement of stimulus associability by the omission of an expected event and to the subsequent expression of that altered associability in more rapid learning. These elements include the amygdala, the midbrain substantia nigra, the basal forebrain substantia innominata, the dorsolateral striatum, the secondary visual cortex, and the posterior parietal cortex. Here, we found that consolidation of a surprise-enhanced associability memory in a serial prediction task depends on processing in the amygdala central nucleus (CeA) after completion of sessions that included the surprising omission of an expected event. Post-surprise infusions of anisomycin, lidocaine, or muscimol prevented subsequent display of surprise-enhanced associability. Because previous studies indicated that CeA function is unnecessary for the expression of associability enhancements that were induced previously when CeA function was intact (Holland & Gallagher, 2006), we interpreted these results as indicating that post-surprise activity of CeA ("surprise replay") is necessary for the consolidation of altered associability memories elsewhere in the brain, such as the posterior parietal cortex (Schiffino et al., 2014a). PMID:27427328

  3. On Parallel Streams through the Mouse Dorsal Lateral Geniculate Nucleus.

    PubMed

    Denman, Daniel J; Contreras, Diego

    2016-01-01

    The mouse visual system is an emerging model for the study of cortical and thalamic circuit function. To maximize the usefulness of this model system, it is important to analyze the similarities and differences between the organization of all levels of the murid visual system with other, better studied systems (e.g., non-human primates and the domestic cat). While the understanding of mouse retina and cortex has expanded rapidly, less is known about mouse dorsal lateral geniculate nucleus (dLGN). Here, we study whether parallel processing streams exist in mouse dLGN. We use a battery of stimuli that have been previously shown to successfully distinguish parallel streams in other species: electrical stimulation of the optic chiasm, contrast-reversing stationary gratings at varying spatial phase, drifting sinusoidal gratings, dense noise for receptive field reconstruction, and frozen contrast-modulating noise. As in the optic nerves of domestic cats and non-human primates, we find evidence for multiple conduction velocity groups after optic chiasm stimulation. As in so-called "visual mammals", we find a subpopulation of mouse dLGN cells showing non-linear spatial summation. However, differences in stimulus selectivity and sensitivity do not provide sufficient basis for identification of clearly distinct classes of relay cells. Nevertheless, consistent with presumptively homologous status of dLGNs of all mammals, there are substantial similarities between response properties of mouse dLGN neurons and those of cats and primates. PMID:27065811

  4. The thalamic reticular nucleus: structure, function and concept.

    PubMed

    Pinault, Didier

    2004-08-01

    On the basis of theoretical, anatomical, psychological and physiological considerations, Francis Crick (1984) proposed that, during selective attention, the thalamic reticular nucleus (TRN) controls the internal attentional searchlight that simultaneously highlights all the neural circuits called on by the object of attention. In other words, he submitted that during either perception, or the preparation and execution of any cognitive and/or motor task, the TRN sets all the corresponding thalamocortical (TC) circuits in motion. Over the last two decades, behavioural, electrophysiological, anatomical and neurochemical findings have been accumulating, supporting the complex nature of the TRN and raising questions about the validity of this speculative hypothesis. Indeed, our knowledge of the actual functioning of the TRN is still sprinkled with unresolved questions. Therefore, the time has come to join forces and discuss some recent cellular and network findings concerning this diencephalic GABAergic structure, which plays important roles during various states of consciousness. On the whole, the present critical survey emphasizes the TRN's complexity, and provides arguments combining anatomy, physiology and cognitive psychology.

  5. Reward prediction error computation in the pedunculopontine tegmental nucleus neurons.

    PubMed

    Kobayashi, Yasushi; Okada, Ken-Ichi

    2007-05-01

    In this article, we address the role of neuronal activity in the pathways of the brainstem-midbrain circuit in reward and the basis for believing that this circuit provides advantages over previous reinforcement learning theory. Several lines of evidence support the reward-based learning theory proposing that midbrain dopamine (DA) neurons send a teaching signal (the reward prediction error signal) to control synaptic plasticity of the projection area. However, the underlying mechanism of where and how the reward prediction error signal is computed still remains unclear. Since the pedunculopontine tegmental nucleus (PPTN) in the brainstem is one of the strongest excitatory input sources to DA neurons, we hypothesized that the PPTN may play an important role in activating DA neurons and reinforcement learning by relaying necessary signals for reward prediction error computation to DA neurons. To investigate the involvement of the PPTN neurons in computation of reward prediction error, we used a visually guided saccade task (VGST) during recording of neuronal activity in monkeys. Here, we predict that PPTN neurons may relay the excitatory component of tonic reward prediction and phasic primary reward signals, and derive a new computational theory of the reward prediction error in DA neurons.

  6. Role of amygdala central nucleus in feature negative discriminations.

    PubMed

    Holland, Peter C

    2012-10-01

    Consistent with a popular theory of associative learning, the Pearce-Hall (1980) model, the surprising omission of expected events enhances cue associability (the ease with which a cue may enter into new associations), across a wide variety of behavioral training procedures. Furthermore, previous experiments from this laboratory showed that these enhancements are absent in rats with impaired function of the amygdala central nucleus (CeA). A notable exception to these assertions is found in feature negative (FN) discrimination learning, in which a "target" stimulus is reinforced when it is presented alone but nonreinforced when it is presented in compound with another, "feature" stimulus. According to the Pearce-Hall model, reinforcer omission on compound trials should enhance the associability of the feature relative to control training conditions. However, prior experiments have shown no evidence that CeA lesions affect FN discrimination learning. Here we explored this apparent contradiction by evaluating the hypothesis that the surprising omission of an event confers enhanced associability on a cue only if that cue itself generates the disconfirmed prediction. Thus, in a FN discrimination, the surprising omission of the reinforcer on compound trials would enhance the associability of the target stimulus but not that of the feature. Our data confirmed this hypothesis and showed this enhancement to depend on intact CeA function, as in other procedures. The results are consistent with modern reformulations of both cue and reward processing theories that assign roles for both individual and aggregate error terms in associative learning.

  7. Effects of therapeutic ultrasound on the nucleus and genomic DNA.

    PubMed

    Furusawa, Yukihiro; Hassan, Mariame A; Zhao, Qing-Li; Ogawa, Ryohei; Tabuchi, Yoshiaki; Kondo, Takashi

    2014-11-01

    In recent years, data have been accumulating on the ability of ultrasound to affect at a distance inside the cell. Previous conceptions about therapeutic ultrasound were mainly based on compromising membrane permeability and triggering some biochemical reactions. However, it was shown that ultrasound can access deep to the nuclear territory resulting in enhanced macromolecular localization as well as alterations in gene and protein expression. Recently, we have reported on the occurrence of DNA double-strand breaks in different human cell lines exposed to ultrasound in vitro with some insight into the subsequent DNA damage response and repair pathways. The impact of these observed effects again sways between extremes. It could be advantageous if employed in gene therapy, wound and bone fracture-accelerated healing to promote cellular proliferation, or in cancer eradication if the DNA lesions would culminate in cell death. However, it could be a worrying sign if they were penultimate to further cellular adaptations to stresses and thus shaking the safety of ultrasound application in diagnosis and therapy. In this review, an overview of the rationale of therapeutic ultrasound and the salient knowledge on ultrasound-induced effects on the nucleus and genomic DNA will be presented. The implications of the findings will be discussed hopefully to provide guidance to future ultrasound research.

  8. NuSTAR catches the unveiling nucleus of NGC 1068

    NASA Astrophysics Data System (ADS)

    Marinucci, A.; Bianchi, S.; Matt, G.; Alexander, D. M.; Baloković, M.; Bauer, F. E.; Brandt, W. N.; Gandhi, P.; Guainazzi, M.; Harrison, F. A.; Iwasawa, K.; Koss, M.; Madsen, K. K.; Nicastro, F.; Puccetti, S.; Ricci, C.; Stern, D.; Walton, D. J.

    2016-02-01

    We present a NuSTAR and XMM-Newton monitoring campaign in 2014/2015 of the Compton-thick Seyfert 2 galaxy, NGC 1068. During the 2014 August observation, we detect with NuSTAR a flux excess above 20 keV (32 ± 6 per cent) with respect to the 2012 December observation and to a later observation performed in 2015 February. We do not detect any spectral variation below 10 keV in the XMM-Newton data. The transient excess can be explained by a temporary decrease of the column density of the obscuring material along the line of sight (from NH ≃ 1025 cm-2 to NH = 6.7 ± 1.0 × 1024 cm-2), which allows us for the first time to unveil the direct nuclear radiation of the buried active galactic nucleus in NGC 1068 and to infer an intrinsic 2-10 keV luminosity L_X=7^{+7}_{-4} × 10^{43} erg s-1.

  9. Ab initio description of the exotic unbound 7He nucleus

    DOE PAGESBeta

    Baroni, Simone; Navratil, Petr; Quaglioni, Sofia

    2013-01-11

    In this study, the neutron-rich unbound 7He nucleus has been the subject of many experimental investigations. While the ground-state 3/2– resonance is well established, there is a controversy concerning the excited 1/2– resonance reported in some experiments as low lying and narrow (ER~1 MeV, Γ≤1 MeV) while in others as very broad and located at a higher energy. This issue cannot be addressed by ab initio theoretical calculations based on traditional bound-state methods. We introduce a new unified approach to nuclear bound and continuum states based on the coupling of the no-core shell model, a bound-state technique, with the no-coremore » shell model combined with the resonating-group method, a nuclear scattering technique. Our calculations describe the ground-state resonance in agreement with experiment and, at the same time, predict a broad 1/2– resonance above 2 MeV.« less

  10. Au nanoinjectors for electrotriggered gene delivery into the cell nucleus.

    PubMed

    Kang, Mijeong; Kim, Bongsoo

    2015-01-01

    Intracellular delivery of exogenous materials is an essential technique required for many fundamental biological researches and medical treatments. As our understanding of cell structure and function has been improved and diverse therapeutic agents with a subcellular site of action have been continuously developed, there is a demand to enhance the performance of delivering devices. Ideal intracellular delivery devices should convey various kinds of exogenous materials without deteriorating cell viability regardless of cell type and, furthermore, precisely control the location and the timing of delivery as well as the amount of delivered materials for advanced researches.In this chapter the development of a new intracellular delivery device, a nanoinjector made of a Au (gold) nanowire (a Au nanoinjector) is described in which delivery is triggered by external application of an electric pulse. As a model study, a gene was delivered directly into the nucleus of a neuroblastoma cell, and successful delivery without cell damage was confirmed by the expression of the delivered gene. The insertion of a Au nanoinjector directly into a cell can be generally applied to any kind of cell, and a high degree of surface modification of Au allows attachment of diverse materials such as proteins, small molecules, or nanoparticles as well as genes on Au nanoinjectors. This expands their applicability, and it is expected that they will provide important information on the effects of delivered exogenous materials and consequently contribute to the development of related therapeutic or clinical technologies.

  11. Hsp90 in Cancer: Transcriptional Roles in the Nucleus.

    PubMed

    Calderwood, Stuart K; Neckers, Len

    2016-01-01

    Hsp90 plays a key role in fostering metabolic pathways essential in tumorigenesis through its functions as a molecular chaperone. Multiple oncogenic factors in the membrane and cytoplasm are thus protected from degradation and destruction. Here, we have considered Hsp90's role in transcription in the nucleus. Hsp90 functions both in regulating the activity of sequence-specific transcription factors such as nuclear receptors and HSF1, as well as impacting more globally acting factors that act on chromatin and RNA polymerase II. Hsp90 influences transcription by modulating histone modification mediated by its clients SMYD3 and trithorax/MLL, as well as by regulating the processivity of RNA polymerase II through negative elongation factor. It is not currently clear how the transcriptional role of Hsp90 may be influenced by the cancer milieu although recently discovered posttranslational modification of the chaperone may be involved. Dysregulation of Hsp90 may thus influence malignant processes both by modulating the function of specific transcription factors and effects on more globally acting general components of the transcriptional machinery. PMID:26916002

  12. Subthalamic nucleus stimulation affects incentive salience attribution in Parkinson's disease.

    PubMed

    Serranová, Tereza; Jech, Robert; Dušek, Petr; Sieger, Tomáš; Růžička, Filip; Urgošík, Dušan; Růžička, Evžen

    2011-10-01

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) can induce nonmotor side effects such as behavioral and mood disturbances or body weight gain in Parkinson's disease (PD) patients. We hypothesized that some of these problems could be related to an altered attribution of incentive salience (ie, emotional relevance) to rewarding and aversive stimuli. Twenty PD patients (all men; mean age ± SD, 58.3 ± 6 years) in bilateral STN DBS switched ON and OFF conditions and 18 matched controls rated pictures selected from the International Affective Picture System according to emotional valence (unpleasantness/pleasantness) and arousal on 2 independent visual scales ranging from 1 to 9. Eighty-four pictures depicting primary rewarding (erotica and food) and aversive fearful (victims and threat) and neutral stimuli were selected for this study. In the STN DBS ON condition, the PD patients attributed lower valence scores to the aversive pictures compared with the OFF condition (P < .01) and compared with controls (P < .01). The difference between the OFF condition and controls was less pronounced (P < .05). Furthermore, postoperative weight gain correlated with arousal ratings from the food pictures in the STN DBS ON condition (P < .05 compensated for OFF condition). Our results suggest that STN DBS increases activation of the aversive motivational system so that more relevance is attributed to aversive fearful stimuli. In addition, STN DBS-related sensitivity to food reward stimuli cues might drive DBS-treated patients to higher food intake and subsequent weight gain. PMID:21780183

  13. Frequency modulated sweep responses in the medial geniculate nucleus.

    PubMed

    Lui, B; Mendelson, J R

    2003-12-01

    A basic feature of communication signals is a dynamic change in frequency. One stimulus that lends itself well to investigating the frequency changes contained in these signals is the frequency modulated (FM) sweep. While many studies have investigated FM sweep responses in the auditory midbrain and cortex, relatively few have examined them in the thalamus. To this end, we investigated the responses of single units in the ventral division of the medial geniculate nucleus (MGNv) of the rat to FM sweeps. Both upward- (changing from low to high frequency) and downward-directed (changing from high to low frequency) FM sweeps were presented at four rates of frequency modulation (i.e., speed). Results showed that the majority (76%) of the cells preferred fast or medium FM sweeps. For direction selectivity, just under half of the units (47%) exhibited a preference for the direction of FM sweep. The results suggest that there is a greater degree of direction but not speed selectivity at progressively higher levels in the auditory pathway.

  14. On Parallel Streams through the Mouse Dorsal Lateral Geniculate Nucleus

    PubMed Central

    Denman, Daniel J.; Contreras, Diego

    2016-01-01

    The mouse visual system is an emerging model for the study of cortical and thalamic circuit function. To maximize the usefulness of this model system, it is important to analyze the similarities and differences between the organization of all levels of the murid visual system with other, better studied systems (e.g., non-human primates and the domestic cat). While the understanding of mouse retina and cortex has expanded rapidly, less is known about mouse dorsal lateral geniculate nucleus (dLGN). Here, we study whether parallel processing streams exist in mouse dLGN. We use a battery of stimuli that have been previously shown to successfully distinguish parallel streams in other species: electrical stimulation of the optic chiasm, contrast-reversing stationary gratings at varying spatial phase, drifting sinusoidal gratings, dense noise for receptive field reconstruction, and frozen contrast-modulating noise. As in the optic nerves of domestic cats and non-human primates, we find evidence for multiple conduction velocity groups after optic chiasm stimulation. As in so-called “visual mammals”, we find a subpopulation of mouse dLGN cells showing non-linear spatial summation. However, differences in stimulus selectivity and sensitivity do not provide sufficient basis for identification of clearly distinct classes of relay cells. Nevertheless, consistent with presumptively homologous status of dLGNs of all mammals, there are substantial similarities between response properties of mouse dLGN neurons and those of cats and primates. PMID:27065811

  15. Solar Sail Application to Comet Nucleus Sample Return

    NASA Technical Reports Server (NTRS)

    Taylor, Travis S.; Moton, Tryshanda T.; Robinson, Don; Anding, R. Charles; Matloff, Gregory L.; Garbe, Gregory; Montgomery, Edward

    2003-01-01

    Many comets have perihelions at distances within 1.0 Astronomical Unit (AU) from the sun. These comets typically are inclined out of the ecliptic. We propose that a solar sail spacecraft could be used to increase the inclination of the orbit to match that of these 1.0 AU comets. The solar sail spacecraft would match the orbit velocity for a short period of time, which would be long enough for a container to be injected into the comet's nucleus. The container would be extended from a long durable tether so that the solar sail would not be required to enter into the potentially degrading environment of the comet s atmosphere. Once the container has been filled with sample material, the tether is retracted. The solar sail would then lower its inclination and fly back to Earth for the sample return. In this paper, we describe the selection of cometary targets, the mission design, and the solar sailcraft design suitable for sail-comet rendezvous as well as possible rendezvous scenarios.

  16. Paraventricular Nucleus Modulates Excitatory Cardiovascular Reflexes during Electroacupuncture

    PubMed Central

    Tjen-A-Looi, Stephanie C.; Guo, Zhi-Ling; Fu, Liang-Wu; Longhurst, John C.

    2016-01-01

    The paraventricular nucleus (PVN) regulates sympathetic outflow and blood pressure. Somatic afferent stimulation activates neurons in the hypothalamic PVN. Parvocellular PVN neurons project to sympathoexcitatory cardiovascular regions of the rostral ventrolateral medulla (rVLM). Electroacupuncture (EA) stimulates the median nerve (P5-P6) to modulate sympathoexcitatory responses. We hypothesized that the PVN and its projections to the rVLM participate in the EA-modulation of sympathoexcitatory cardiovascular responses. Cats were anesthetized and ventilated. Heart rate and mean blood pressure were monitored. Application of bradykinin every 10-min on the gallbladder induced consistent pressor reflex responses. Thirty-min of bilateral EA stimulation at acupoints P5-P6 reduced the pressor responses for at least 60-min. Inhibition of the PVN with naloxone reversed the EA-inhibition. Responses of cardiovascular barosensitive rVLM neurons evoked by splanchnic nerve stimulation were reduced by EA and then restored with opioid receptor blockade in the PVN. EA at P5-P6 decreased splanchnic evoked activity of cardiovascular barosensitive PVN neurons that also project directly to the rVLM. PVN neurons labeled with retrograde tracer from rVLM were co-labeled with μ-opioid receptors and juxtaposed to endorphinergic fibers. Thus, the PVN and its projection to rVLM are important in processing acupuncture modulation of elevated blood pressure responses through a PVN opioid mechanism. PMID:27181844

  17. Recording Gamma Band Oscillations in Pedunculopontine Nucleus Neurons.

    PubMed

    Urbano, Francisco J; Luster, Brennon R; D'Onofrio, Stasia; Mahaffey, Susan; Garcia-Rill, Edgar

    2016-09-14

    Synaptic efferents from the PPN are known to modulate the neuronal activity of several intralaminar thalamic regions (e.g., the centrolateral/parafascicular; Cl/Pf nucleus). The activation of either the PPN or Cl/Pf nuclei in vivo has been described to induce the arousal of the animal and an increment in gamma band activity in the cortical electroencephalogram (EEG). The cellular mechanisms for the generation of gamma band oscillations in Reticular Activating System (RAS) neurons are the same as those found to generate gamma band oscillations in other brains nuclei. During current-clamp recordings of PPN neurons (from parasagittal slices from 9 - 25 day-old rats), the use of depolarizing square steps rapidly activated voltage-dependent potassium channels that prevented PPN neurons from being depolarized beyond -25 mV. Injecting 1 - 2 sec long depolarizing current ramps gradually depolarized PPN membrane potential resting values towards 0 mV. However, injecting depolarizing square pulses generated gamma-band oscillations of membrane potential that showed to be smaller in amplitude compared to the oscillations generated by ramps. All experiments were performed in the presence of voltage-gated sodium channels and fast synaptic receptors blockers. It has been shown that the activation of high-threshold voltage-dependent calcium channels underlie gamma-band oscillatory activity in PPN neurons. Specific methodological and pharmacological interventions are described here, providing the necessary tools to induce and sustain PPN subthreshold gamma band oscillation in vitro.

  18. Implications of gamma band activity in the pedunculopontine nucleus.

    PubMed

    Garcia-Rill, E; Luster, B; D'Onofrio, S; Mahaffey, S; Bisagno, V; Urbano, F J

    2016-07-01

    The fact that the pedunculopontine nucleus (PPN) is part of the reticular activating system places it in a unique position to modulate sensory input and fight-or-flight responses. Arousing stimuli simultaneously activate ascending projections of the PPN to the intralaminar thalamus to trigger cortical high-frequency activity and arousal, as well as descending projections to reticulospinal systems to alter posture and locomotion. As such, the PPN has become a target for deep brain stimulation for the treatment of Parkinson's disease, modulating gait, posture, and higher functions. This article describes the latest discoveries on PPN physiology and the role of the PPN in a number of disorders. It has now been determined that high-frequency activity during waking and REM sleep is controlled by two different intracellular pathways and two calcium channels in PPN cells. Moreover, there are three different PPN cell types that have one or both calcium channels and may be active during waking only, REM sleep only, or both. Based on the new discoveries, novel mechanisms are proposed for insomnia as a waking disorder. In addition, neuronal calcium sensor protein-1 (NCS-1), which is over expressed in schizophrenia and bipolar disorder, may be responsible for the dysregulation in gamma band activity in at least some patients with these diseases. Recent results suggest that NCS-1 modulates PPN gamma band activity and that lithium acts to reduce the effects of over expressed NCS-1, accounting for its effectiveness in bipolar disorder.

  19. Spontaneous fission of the superheavy nucleus 286Fl

    NASA Astrophysics Data System (ADS)

    Poenaru, D. N.; Gherghescu, R. A.

    2016-07-01

    The decimal logarithm of spontaneous fission half-life of the superheavy nucleus 286Fl experimentally determined is log10Tfexp(s ) =-0.632 . We present a method to calculate the half-life based on the cranking inertia and the deformation energy, functions of two independent surface coordinates, using the best asymmetric two center shell model. Spherical shapes are assumed. In the first stage we study the statics. At a given mass asymmetry up to about η =0.5 the potential barrier has a two hump shape, but for larger η it has only one hump. The touching point deformation energy versus mass asymmetry shows the three minima, produced by shell effects, corresponding to three decay modes: spontaneous fission, cluster decay, and α decay. The least action trajectory is determined in the plane (R ,η ) , where R is the separation distance of the fission fragments and η is the mass asymmetry. We may find a sequence of several trajectories one of which gives the least action. The parametrization with two deformation coordinates (R ,η ) and the radius of the light fragment, R2, exponentially or linearly decreasing with R is compared with the simpler one, in which R2=constant and with a linearly decreasing or linearly increasing R2. The latter is closer to the reality and reminds us about the α or cluster preformation at the nuclear surface.

  20. MDMA modulates spontaneous firing of subthalamic nucleus neurons in vitro.

    PubMed

    Liebig, Luise; von Ameln-Mayerhofer, Andreas; Hentschke, Harald

    2015-01-01

    3,4-Methylene-dioxy-N-methylamphetamine (MDMA, 'ecstasy') has a broad spectrum of molecular targets in the brain, among them receptors and transporters of the serotonergic (5-hydroxytryptamine, 5-HT) and noradrenergic systems. Its action on the serotonergic system modulates motor systems in rodents and humans. Although parts of the basal ganglia could be identified as mediators of the motor effects of MDMA, very little is known about the role of the subthalamic nucleus (STN). Therefore, this study investigated the modulation of spontaneous action potential activity of the STN by MDMA (2.5-20 µM) in vitro. MDMA had very heterogeneous effects, ranging from a complete but reversible inhibition to a more than twofold increase in firing at 5 µM. On average, MDMA excited STN neurons moderately, but lost its excitatory effect in the presence of the 5-HT(2A) antagonist MDL 11,939. 5-HT(1A) receptors did not appear to play a major role. Effects of MDMA on transporters for serotonin (SERT) and norepinephrine (NET) were investigated by coapplication of the reuptake inhibitors citalopram and desipramine, respectively. Similar to the effects of 5-HT(2A) receptor blockade, antagonism of SERT and NET bestowed an inhibitory effect on MDMA. From these results, we conclude that both the 5-HT and the noradrenergic system mediate MDMA-induced effects on STN neurons.

  1. SUNrises on the International Plant Nucleus Consortium: SEB Salzburg 2012.

    PubMed

    Graumann, Katja; Bass, Hank W; Parry, Geraint

    2013-01-01

    The nuclear periphery is a dynamic, structured environment, whose precise functions are essential for global processes-from nuclear, to cellular, to organismal. Its main components-the nuclear envelope (NE) with inner and outer nuclear membranes (INM and ONM), nuclear pore complexes (NPC), associated cytoskeletal and nucleoskeletal components as well as chromatin are conserved across eukaryotes (Fig. 1). In metazoans in particular, the structure and functions of nuclear periphery components are intensely researched partly because of their involvement in various human diseases. While far less is known about these in plants, the last few years have seen a significant increase in research activity in this area. Plant biologists are not only catching up with the animal field, but recent findings are pushing our advances in this field globally. In recognition of this developing field, the Annual Society of Experimental Biology Meeting in Salzburg kindly hosted a session co-organized by Katja Graumann and David E. Evans (Oxford Brookes University) highlighting new insights into plant nuclear envelope proteins and their interactions. This session brought together leading researchers with expertise in topics such as epigenetics, meiosis, nuclear pore structure and functions, nucleoskeleton and nuclear envelope composition. An open and friendly exchange of ideas was fundamental to the success of the meeting, which resulted in founding the International Plant Nucleus Consortium. This review highlights new developments in plant nuclear envelope research presented at the conference and their importance for the wider understanding of metazoan, yeast and plant nuclear envelope functions and properties.

  2. Nicotinic modulation of serotonergic activity in the dorsal raphe nucleus.

    PubMed

    Hernandez-Lopez, Salvador; Garduño, Julieta; Mihailescu, Stefan

    2013-01-01

    Cholinergic signaling mediated by nicotinic receptors has been associated to a large number of physiological and behavioral processes such as learning, memory, attention, food-intake and mood disorders. Although it is well established that many nicotinic actions are mediated through an increase in serotonin (5-HT) release, the physiological mechanisms by which nicotine produces these effects are still unclear. The dorsal raphe nucleus (DRN) contains the major amount of 5-HT neurons projecting to different parts of the brain. DRN also contains nicotinic acetylcholine receptors (nAChRs) located at somatic and presynaptic elements. Nicotine produces both inhibitory and excitatory effects on different subpopulations of 5-HT DRN neurons. In this review, we describe the presynaptic and postsynaptic mechanisms by which nicotine increases the excitability of DRN neurons as well as the subtypes of nAChRs involved. We also describe the inhibitory effects of nicotine and the role of 5-HT1A receptors in this effect. These nicotinic actions modulate the activity of different neuronal subpopulations in the DRN, changing the 5-HT tone in the brain areas where these groups of neurons project. Some of the physiological implications of nicotine-induced 5-HT release are discussed. PMID:24021594

  3. The role of pedunculopontine nucleus in choice behavior under risk.

    PubMed

    Leblond, Mona; Sukharnikova, Tatyana; Yu, Chunxiu; Rossi, Mark A; Yin, Henry H

    2014-05-01

    The dopaminergic projections to the basal ganglia have long been implicated in reward-guided behavior and decision-making, yet little is known about the role of the posterior pedunculopontine nucleus (pPPN), a major source of excitatory input to the mesolimbic dopamine system. Here we studied the contributions of the pPPN to decision-making under risk, using excitoxic lesions and reversible inactivation in rats. Rats could choose between two options - a small but certain reward on one lever; or a large but uncertain reward on the other lever. The overall payoff associated with each choice is the same, but the reward variance (risk) associated with the risky choice is much higher. In Experiment 1, we showed that excitotoxic lesions of the pPPN before training did not affect acquisition of lever pressing. But whereas the controls strongly preferred the safe choice, the lesioned rats did not. In Experiment 2, we found that muscimol inactivation of the pPPN also produced similar effects, but reversibly. These results show that permanent lesions or reversible inactivation of the pPPN both abolish risk aversion in decision-making.

  4. Jet-like features near the Nucleus of Chiron

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; Olkin, C. B.; Dunham, E. W.; Ford, C. H.; Gilmore, D. K.; Kurtz, D.; Lazzaro, D.; Rank, D. M.; Temi, P.; Bandyopadhyay, R. M.; Barroso, J.; Barrucci, A.; Bosh, A. S.; Buie, M. W.; Bus, S. J.; Dahn, C. C.; Foryta, D. W.; Hubbard, W. B.; Lopes, D. F.; Marcialis, R. L.

    1995-01-01

    Considered as a comet, the object 2060 Chiron is unusual in two respects: it exhibits outbursts at very large distances from the Sun, and its nucleus is much larger than that of any other known comet. It is, however, similar in size to the recently discovered Kuiper-belt objects - a population of objects with orbits beyond Neptune, which are a possible source of short-period comets. This has led to the conjecture that Chiron is related to these objects, but its chaotic orbit has brought it much closer to the Sun. Here we report observations of a recent stellar occultation by Chiron which permit the identification of several features associated with Chiron's coma. The observation of discrete, jet-like features provides evidence that the coma material originates from just few, small active areas, rather than from uniform sublimations, and that the particles in at least one of these features have radii greater than 0.25 microns. The observations also suggest the presence of material in the plane of Chiron's orbit and are consistent with a gravitationally bound coma. Finally, the present data, and those from a previous occultation, constrain the radius of Chiron to lie between 83 and 156 km.

  5. Morphological differences in the lateral geniculate nucleus associated with dyslexia.

    PubMed

    Giraldo-Chica, Mónica; Hegarty, John P; Schneider, Keith A

    2015-01-01

    Developmental dyslexia is a common learning disability characterized by normal intelligence but difficulty in skills associated with reading, writing and spelling. One of the most prominent, albeit controversial, theories of dyslexia is the magnocellular theory, which suggests that malfunction of the magnocellular system in the brain is responsible for the behavioral deficits. We sought to test the basis of this theory by directly measuring the lateral geniculate nucleus (LGN), the only location in the brain where the magnocellular and parvocellular streams are spatially disjoint. Using high-resolution proton-density weighted MRI scans, we precisely measured the anatomical boundaries of the LGN in 13 subjects with dyslexia (five female) and 13 controls (three female), all 22-26 years old. The left LGN was significantly smaller in volume in subjects with dyslexia and also differed in shape; no differences were observed in the right LGN. The functional significance of this asymmetry is unknown, but these results are consistent with the magnocellular theory and support theories of dyslexia that involve differences in the early visual system. PMID:26082892

  6. Elastic and inelastic scattering of neutrons on 238U nucleus

    NASA Astrophysics Data System (ADS)

    Capote, R.; Trkov, A.; Sin, M.; Herman, M. W.; Soukhovitskiĩ, E. Sh.

    2014-04-01

    Advanced modelling of neutron induced reactions on the 238U nucleus is aimed at improving our knowledge of neutron scattering. Capture and fission channels are well constrained by available experimental data and neutron standard evaluation. A focus of this contribution is on elastic and inelastic scattering cross sections. The employed nuclear reaction model includes - a new rotational-vibrational dispersive optical model potential coupling the low-lying collective bands of vibrational character observed in even-even actinides; - the Engelbrecht-Weidenmüller transformation allowing for inclusion of compound-direct interference effects; - and a multi-humped fission barrier with absorption in the secondary well described within the optical model for fission. Impact of the advanced modelling on elastic and inelastic scattering cross sections including angular distributions and emission spectra is assessed both by comparison with selected microscopic experimental data and integral criticality benchmarks including measured reaction rates (e.g. JEMIMA, FLAPTOP and BIG TEN). Benchmark calculations provided feedback to improve the reaction modelling. Improvement of existing libraries will be discussed.

  7. Caudate Nucleus in Retrieval of Trace Eyeblink Conditioning after Consolidation

    PubMed Central

    Flores, Luke C.; Disterhoft, John F.

    2013-01-01

    Trace eyeblink conditioning (EBC) is an associative learning task in which a stimulus-free trace period separates the presentation of a behaviorally neutral conditioned stimulus (CS, whisker stimulation) from a behaviorally salient unconditioned stimulus (US, airpuff to the eye). Repeated pairings of the CS with the US results in the emergence of the conditioned response (CR, eyeblink following CS presentation and preceding US presentation). The goal of these experiments was to determine whether the caudate nucleus (CN) plays a role in retrieval of previously acquired trace EBC after memory consolidation. Lesions of the CN were made one month after initial trace EBC. CN lesioned rabbits performed fewer adaptive CRs and more short-latency non-adaptive responses than sham lesioned controls. They were not able to improve their CR performance after consolidation as were controls. Single unit recordings taken from separate cohorts of rabbits demonstrated that neurons in the CN were still responsive to the CS and US one month after initial trace EBC, particularly in the medial and ventral CN on trials when a CR occurred. The proportion of rate increasing neurons was higher in trace conditioned than in pseudo conditioned rabbits. Neurons in regions destroyed in the behavioral experiment demonstrated prolonged firing during the trace period, which might underlie the results from the behavioral experiment. These data demonstrate that the CN plays an important role in retrieval of a previously learned associative task after memory consolidation has occurred. PMID:23407942

  8. Cellular Mechanosensing: Getting to the nucleus of it all

    PubMed Central

    Fedorchak, Gregory R.; Kaminski, Ashley; Lammerding, Jan

    2014-01-01

    Cells respond to mechanical forces by activating specific genes and signaling pathways that allow the cells to adapt to their physical environment. Examples include muscle growth in response to exercise, bone remodeling based on their mechanical load, or endothelial cells aligning under fluid shear stress. While the involved downstream signaling pathways and mechanoresponsive genes are generally well characterized, many of the molecular mechanisms of the initiating ‘mechanosensing’ remain still elusive. In this review, we discuss recent findings and accumulating evidence suggesting that the cell nucleus plays a crucial role in cellular mechanotransduction, including processing incoming mechanoresponsive signals and even directly responding to mechanical forces. Consequently, mutations in the involved proteins or changes in nuclear envelope composition can directly impact mechanotransduction signaling and contribute to the development and progression of a variety of human diseases, including muscular dystrophy, cancer, and the focus of this review, dilated cardiomyopathy. Improved insights into the molecular mechanisms underlying nuclear mechanotransduction, brought in part by the emergence of new technologies to study intracellular mechanics at high spatial and temporal resolution, will not only result in a better understanding of cellular mechanosensing in normal cells but may also lead to the development of novel therapies in the many diseases linked to defects in nuclear envelope proteins. PMID:25008017

  9. Lifetime measurements in the transitional nucleus {sup 138}Gd

    SciTech Connect

    Procter, M. G.; Cullen, D. M.; Taylor, M. J.; Ruotsalainen, P.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Lopez-Martens, A.; Leino, M.; Nieminen, P.; Peura, P.; Rahkila, P.; Rinta-Antilla, S.; Sandzelius, M.; Saren, J.

    2011-08-15

    Lifetime measurements have been made in the ground-state band of the transitional nucleus {sup 138}Gd from coincidence recoil-distance Doppler-shift data. {sup 138}Gd nuclei were produced using the {sup 106}Cd ({sup 36}Ar, 2p2n) reaction with a beam energy of 190 MeV. Reduced transition probabilities have been extracted from the lifetime data collected with the Koeln plunger placed at the target position of the JUROGAM-II array. The B(E2) values have been compared with predictions from X(5) critical-point calculations, which describe the phase transition between vibrational and axially symmetric nuclear shapes, as well as with IBM-1 calculations at the critical point. While the excitation energies in {sup 138}Gd are consistent with X(5) predictions, the large uncertainties associated with the measured B(E2) values cannot preclude vibrational and rotational contributions to the low-lying structure of {sup 138}Gd. Although experimental knowledge for the low-lying {gamma} and {beta}-vibrational bands in {sup 138}Gd is limited, potential-energy surface calculations suggest an increase in {gamma} softness in the ground-state band. In order to more fully account for the effects of {gamma} softness, the X(5) and IBM-1 calculations need to be extended to include the {gamma} degree of freedom for {sup 138}Gd.

  10. Whole transcriptome organisation in the dehydrated supraoptic nucleus.

    PubMed

    Hindmarch, C C T; Franses, P; Goodwin, B; Murphy, D

    2013-12-01

    The supraoptic nucleus (SON) is part of the central osmotic circuitry that synthesises the hormone vasopressin (Avp) and transports it to terminals in the posterior lobe of the pituitary. Following osmotic stress such as dehydration, this tissue undergoes morphological, electrical and transcriptional changes to facilitate the appropriate regulation and release of Avp into the circulation where it conserves water at the level of the kidney. Here, the organisation of the whole transcriptome following dehydration is modelled to fit Zipf's law, a natural power law that holds true for all natural languages, that states if the frequency of word usage is plotted against its rank, then the log linear regression of this is -1. We have applied this model to our previously published euhydrated and dehydrated SON data to observe this trend and how it changes following dehydration. In accordance with other studies, our whole transcriptome data fit well with this model in the euhydrated SON microarrays, but interestingly, fit better in the dehydrated arrays. This trend was observed in a subset of differentially regulated genes and also following network reconstruction using a third-party database that mines public data. We make use of language as a metaphor that helps us philosophise about the role of the whole transcriptome in providing a suitable environment for the delivery of Avp following a survival threat like dehydration. PMID:24345907

  11. Modulation of Locomotor Activation by the Rostromedial Tegmental Nucleus

    PubMed Central

    Lavezzi, Heather N; Parsley, Kenneth P; Zahm, Daniel S

    2015-01-01

    The rostromedial tegmental nucleus (RMTg) is a strong inhibitor of dopamine neurons in the ventral tegmental area (VTA) reported to influence neurobiological and behavioral responses to reward omission, aversive and fear-eliciting stimuli, and certain drugs of abuse. Insofar as previous studies implicate ventral mesencephalic dopamine neurons as an essential component of locomotor activation, we hypothesized that the RMTg also should modulate locomotion activation. We observed that bilateral infusions into the RMTg of the gamma-aminobutyric acid A (GABAA) agonist, muscimol, indeed activate locomotion. Alternatively, bilateral RMTg infusions of the GABAA receptor antagonist, bicuculline, suppress robust activations of locomotion elicited in two distinct ways: (1) by disinhibitory stimulation of neurons in the lateral preoptic area and (2) by return of rats to an environment previously paired with amphetamine administration. The possibility that suppressive locomotor effects of RMTg bicuculline infusions were due to unintended spread of drug to the nearby VTA was falsified by a control experiment showing that bilateral infusions of bicuculline into the VTA produce activation rather than suppression of locomotion. These results objectively implicate the RMTg in the regulation of locomotor activation. The effect is important because much evidence reported in the literature suggests that locomotor activation can be an involuntary behavioral expression of expectation and/or want without which the willingness to execute adaptive behaviors is impaired. PMID:25164249

  12. PHARMACOLOGIC TREATMENT OF HYPERALGESIA EXPERIMENTALLY INDUCED BY NUCLEUS PULPOSUS

    PubMed Central

    de Souza Grava, André Luiz; Ferrari, Luiz Fernando; Parada, Carlos Amílcar; Defino, Helton Luiz Aparecido

    2015-01-01

    Objective: To evaluate the effect of anti-inflammatory drugs (dexamethasone, indomethacin, atenolol and indomethacin plus atenolol) and analgesic drugs (morphine) on hyperalgesia experimentally induced by the nucleus pulposus (NP) in contact with the L5 dorsal root ganglion (DRG). Methods: Thirty male Wistar rats of weights ranging from 220 to 250 g were used in the study. Hyperalgesia was induced by means of a fragment of NP removed from the sacrococcygeal region that was placed in contact with the L5 dorsal root ganglion. The 30 animals were divided into experimental groups according to the drug used. The drugs were administered for two weeks after the surgical procedure to induce hyperalgesia. Mechanical and thermal hyperalgesia was evaluated using the paw pressure test, von Frey electronic test and Hargreaves test, over a seven-week period. Results: The greatest reduction of hyperalgesia was observed in the group of animals treated with morphine, followed by dexamethasone, indomethacin and atenolol. Reductions in hyperalgesia were observed after drug administration ceased, except for the group of animals treated with morphine, in which there was an increase in hyperalgesia after discontinuation of the treatment. Conclusion: Hyperalgesia induced by NP contact with the DRG can be reduced through administration of anti-inflammatory and analgesic drugs, but a greater reduction was observed with the administration of dexamethasone. PMID:27026966

  13. Morphological differences in the lateral geniculate nucleus associated with dyslexia

    PubMed Central

    Giraldo-Chica, Mónica; Hegarty, John P.; Schneider, Keith A.

    2015-01-01

    Developmental dyslexia is a common learning disability characterized by normal intelligence but difficulty in skills associated with reading, writing and spelling. One of the most prominent, albeit controversial, theories of dyslexia is the magnocellular theory, which suggests that malfunction of the magnocellular system in the brain is responsible for the behavioral deficits. We sought to test the basis of this theory by directly measuring the lateral geniculate nucleus (LGN), the only location in the brain where the magnocellular and parvocellular streams are spatially disjoint. Using high-resolution proton-density weighted MRI scans, we precisely measured the anatomical boundaries of the LGN in 13 subjects with dyslexia (five female) and 13 controls (three female), all 22–26 years old. The left LGN was significantly smaller in volume in subjects with dyslexia and also differed in shape; no differences were observed in the right LGN. The functional significance of this asymmetry is unknown, but these results are consistent with the magnocellular theory and support theories of dyslexia that involve differences in the early visual system. PMID:26082892

  14. Mesopontine cholinergic projections to the hypoglossal motor nucleus.

    PubMed

    Rukhadze, Irma; Kubin, Leszek

    2007-02-14

    Mesopontine cholinergic (ACh) neurons have increased discharge during wakefulness, rapid eye movement (REM) sleep, or both. Hypoglossal (12) motoneurons, which play an important role in the control of upper airway patency, are postsynaptically excited by stimulation of nicotinic receptors, whereas muscarinic receptors presynaptically inhibit inputs to 12 motoneurons. These data suggest that ACh contributes to sleep/wake-related changes in the activity of 12 motoneurons by acting within the hypoglossal motor nucleus (Mo12), but the origins of ACh projections to Mo12 are not well established. We used retrograde tracers to assess the projections of ACh neurons of the mesopontine pedinculopontine tegmental (PPT) and laterodorsal tegmental (LDT) nuclei to the Mo12. In six Sprague-Dawley rats, Fluorogold or B subunit of cholera toxin, were pressure injected (5-20nl) into the Mo12. Retrogradely labeled neurons, identified as ACh using nitric oxide synthase (NOS) immunohistochemistry, were found bilaterally in discrete subregions of both PPT and LDT nuclei. Most retrogradely labeled PPT cells (96%) were located in the PPT pars compacta region adjacent to the ventrolateral tip of the superior cerebellar peduncle. In the LDT, retrogradely labeled neurons were located exclusively in its pars alpha region. Over twice as many ACh neurons projecting to the Mo12 were located in the PPT than LDT. The results demonstrate direct mesopontine ACh projections to the Mo12. These projections may contribute to the characteristic of wakefulness and REM sleep increases, as well as REM sleep-related decrements, of 12 motoneuronal activity.

  15. GABAergic processes within the median preoptic nucleus promote NREM sleep.

    PubMed

    Benedetto, Luciana; Chase, Michael H; Torterolo, Pablo

    2012-06-15

    GABAergic mechanisms in the preoptic region of the hypothalamus (POA) have been implicated in the generation and maintenance of NREM (quiet) sleep. We recently reported that neurons in the median peptic nucleus (MnPN) in the POA of the cat are selectively activated during NREM sleep. In the present study, we explored the hypothesis that NREM sleep is controlled by GABAergic mechanisms within the MnPN. Consequently, adult cats were utilized to determine GABA immunorreactivity within the MnPN and to examine the effects on sleep of the microinjection of a GABA(A) agonist (muscimol) and a GABA(A) antagonist (bicuculline) into this area. GABAergic neurons were present throughout the MnPN. Compared with control microinjections, after the application of muscimol, the time spent in NREM sleep (59.8±7.5 min) and REM sleep (6.9±4.7 min) decreased compared with control microinjections (103.8±5.2 and 20.2±4.3 min, respectively; P<0.005). In contrast, bicuculline microinjections increased only NREM sleep time (103.0±23.0 vs 77.7±23.7 min; P<0.05). These results demonstrate that GABAergic processes within the MnPN are involved in the generation and maintenance of sleep, especially NREM sleep.

  16. Left nucleus accumbens atrophy in deficit schizophrenia: A preliminary study.

    PubMed

    De Rossi, Pietro; Dacquino, Claudia; Piras, Fabrizio; Caltagirone, Carlo; Spalletta, Gianfranco

    2016-08-30

    A question that remains to be answered is whether schizophrenia can be characterized by a single etiopathophysiology or whether separate sub-syndromes should be differentiated to define specific mechanisms for each sub-type. Individuals affected by the deficit subtype of schizophrenia (DSZ) display avolitional/amotivational features that respond poorly to conventional treatments. Characterizing DSZ from a neuroanatomical point of view may help clarify this issue and develop new treatment strategies. To determine if DSZ is associated with structural alterations in specific deep grey matter structures linked to its key clinical features, 22 DSZ patients, 22 non-deficit schizophrenia (NDSZ) patients and 22 healthy controls (HC) were recruited for a case-control cross-sectional study. High-resolution magnetic resonance imaging was performed in all subjects and volumes of deep grey matter structures were measured using FreeSurfer. DSZ patients displayed smaller left accumbens volumes compared to both NDSZ patients and HC. Moreover, age and duration of illness were significantly associated with lower volume of the left accumbens in DSZ but not in NDSZ. Findings indicate that DSZ is associated with lower volume of the nucleus accumbens in the dominant hemisphere. This is consistent with the psychopathological features and functional impairments present in DSZ and thus indicates a potential mechanism. PMID:27322868

  17. The Subthalamic Nucleus, Limbic Function, and Impulse Control.

    PubMed

    Rossi, P Justin; Gunduz, Aysegul; Okun, Michael S

    2015-12-01

    It has been well documented that deep brain stimulation (DBS) of the subthalamic nucleus (STN) to address some of the disabling motor symptoms of Parkinson's disease (PD) can evoke unintended effects, especially on non-motor behavior. This observation has catalyzed more than a decade of research concentrated on establishing trends and identifying potential mechanisms for these non-motor effects. While many issues remain unresolved, the collective result of many research studies and clinical observations has been a general recognition of the role of the STN in mediating limbic function. In particular, the STN has been implicated in impulse control and the related construct of valence processing. A better understanding of STN involvement in these phenomena could have important implications for treating impulse control disorders (ICDs). ICDs affect up to 40% of PD patients on dopamine agonist therapy and approximately 15% of PD patients overall. ICDs have been reported to be associated with STN DBS. In this paper we will focus on impulse control and review pre-clinical, clinical, behavioral, imaging, and electrophysiological studies pertaining to the limbic function of the STN.

  18. Deuterium target data for precision neutrino-nucleus cross sections

    DOE PAGESBeta

    Meyer, Aaron S.; Betancourt, Minerba; Gran, Richard; Hill, Richard J.

    2016-06-23

    Amplitudes derived from scattering data on elementary targets are basic inputs to neutrino-nucleus cross section predictions. A prominent example is the isovector axial nucleon form factor, FA(q2), which controls charged current signal processes at accelerator-based neutrino oscillation experiments. Previous extractions of FA from neutrino-deuteron scattering data rely on a dipole shape assumption that introduces an unquantified error. A new analysis of world data for neutrino-deuteron scattering is performed using a model-independent, and systematically improvable, representation of FA. A complete error budget for the nucleon isovector axial radius leads to rA2 = 0.46(22)fm2, with a much larger uncertainty than determined inmore » the original analyses. The quasielastic neutrino-neutron cross section is determined as σ(νμn → μ-p)|Ev=1GeV = 10.1(0.9)×10-39cm2. The propagation of nucleon-level constraints and uncertainties to nuclear cross sections is illustrated using MINERvA data and the GENIE event generator. Furthermore, these techniques can be readily extended to other amplitudes and processes.« less

  19. On the spin order transfer from parahydrogen to another nucleus

    NASA Astrophysics Data System (ADS)

    Bär, Sébastien; Lange, Thomas; Leibfritz, Dieter; Hennig, Jürgen; von Elverfeldt, Dominik; Hövener, Jan-Bernd

    2012-12-01

    The hyperpolarization of nuclear spins holds great potential e.g. for biomedical research. Strong signal enhancements have been demonstrated e.g. by transforming the spin order of parahydrogen (pH2) to net polarization of a third nucleus (e.g. 13C) by means of a spin-order-transfer (SOT) sequence. The polarization achieved is vitally dependent on the sequence intervals, which are a function of the J-coupling constants of the molecule to be polarized. How to derive the SOT sequence intervals, the actual values for molecules as well as the (theoretical) polarization yield and robustness, however, are not fully described. In this paper, (a) we provide the methods to obtain the SOT intervals for a given set of J-coupling constants (i.e. of a new hyperpolarization agent); (b) exemplify these methods on molecules from literature, providing the hitherto missing intervals and simulated polarization yield; and (c) assess the robustness of the sequences towards B1 and J-coupling errors. Close to unity polarization is obtained for all molecules and sequences. Furthermore, the loss of polarization caused by erroneous B1 and J-coupling constants is reduced by choosing the channel and phase of some pulses in the SOT sequences appropriately.

  20. In vivo histamine voltammetry in the mouse premammillary nucleus.

    PubMed

    Samaranayake, Srimal; Abdalla, Aya; Robke, Rhiannon; Wood, Kevin M; Zeqja, Anisa; Hashemi, Parastoo

    2015-06-01

    Histamine plays a major role in the mediation of allergic reactions such as peripheral inflammation. This classical monoamine is also a neurotransmitter involved in the central nervous system but its role in this context is poorly understood. Studying histamine neurotransmission is important due to its implications in many neurological disorders. The sensitivity, selectivity and high temporal resolution of fast scan cyclic voltammetry (FSCV) offer many advantages for studying electroactive neurotransmitters. Histamine has previously been studied with FSCV; however, the lack of a robust Faradaic electrochemical signal makes it difficult to selectively identify histamine in complex media, as found in vivo. In this work, we optimize an electrochemical waveform that provides a stimulation-locked and unique electrochemical signal towards histamine. We describe in vitro waveform optimization and a novel in vivo physiological model for stimulating histamine release in the mouse premammillary nucleus via stimulation of the medial forebrain bundle. We demonstrate that a robust signal can be used to effectively identify histamine and characterize its in vivo kinetics.

  1. Motor task event detection using Subthalamic Nucleus Local Field Potentials.

    PubMed

    Niketeghad, Soroush; Hebb, Adam O; Nedrud, Joshua; Hanrahan, Sara J; Mahoor, Mohammad H

    2015-08-01

    Deep Brain Stimulation (DBS) provides significant therapeutic benefit for movement disorders such as Parkinson's disease. Current DBS devices lack real-time feedback (thus are open loop) and stimulation parameters are adjusted during scheduled visits with a clinician. A closed-loop DBS system may reduce power consumption and DBS side effects. In such systems, DBS parameters are adjusted based on patient's behavior, which means that behavior detection is a major step in designing such systems. Various physiological signals can be used to recognize the behaviors. Subthalamic Nucleus (STN) Local Field Potential (LFP) is a great candidate signal for the neural feedback, because it can be recorded from the stimulation lead and does not require additional sensors. A practical behavior detection method should be able to detect behaviors asynchronously meaning that it should not use any prior knowledge of behavior onsets. In this paper, we introduce a behavior detection method that is able to asynchronously detect the finger movements of Parkinson patients. As a result of this study, we learned that there is a motor-modulated inter-hemispheric connectivity between LFP signals recorded bilaterally from STN. We used non-linear regression method to measure this connectivity and use it to detect the finger movements. Performance of this method is evaluated using Receiver Operating Characteristic (ROC). PMID:26737550

  2. Whole transcriptome organisation in the dehydrated supraoptic nucleus

    PubMed Central

    Hindmarch, C.C.T.; Franses, P.; Goodwin, B.; Murphy, D.

    2013-01-01

    The supraoptic nucleus (SON) is part of the central osmotic circuitry that synthesises the hormone vasopressin (Avp) and transports it to terminals in the posterior lobe of the pituitary. Following osmotic stress such as dehydration, this tissue undergoes morphological, electrical and transcriptional changes to facilitate the appropriate regulation and release of Avp into the circulation where it conserves water at the level of the kidney. Here, the organisation of the whole transcriptome following dehydration is modelled to fit Zipf's law, a natural power law that holds true for all natural languages, that states if the frequency of word usage is plotted against its rank, then the log linear regression of this is -1. We have applied this model to our previously published euhydrated and dehydrated SON data to observe this trend and how it changes following dehydration. In accordance with other studies, our whole transcriptome data fit well with this model in the euhydrated SON microarrays, but interestingly, fit better in the dehydrated arrays. This trend was observed in a subset of differentially regulated genes and also following network reconstruction using a third-party database that mines public data. We make use of language as a metaphor that helps us philosophise about the role of the whole transcriptome in providing a suitable environment for the delivery of Avp following a survival threat like dehydration. PMID:24345907

  3. Spontaneous resorption of a large cervical herniated nucleus pulposus.

    PubMed

    Cvetanovich, Gregory L; Hsu, Andrew R; Frank, Rachel M; An, Howard S; Andersson, Gunnar B

    2014-07-01

    The majority of patients with symptomatic herniated discs can be successfully and conservatively managed and can achieve clinical improvement without surgical intervention. Resorption of the herniated nucleus pulposus (HNP) is 1 conservative mechanism for clinical improvement. We present the case of a 76-year-old healthy man with acute cervical radicular right arm pain and positive Spurling test. Magnetic resonance imaging (MRI) showed a large disc extrusion behind the C6 vertebral body, causing severe central canal stenosis and right-greater-than-left foraminal stenosis. The patient did not want surgical intervention, and his symptoms resolved with conservative treatment. A follow-up MRI 7 months after his initial presentation showed almost complete resorption of the herniated disc. The patient returned to his normal activities and has not had recurrence of symptoms for 2 years. This report provides an interesting example of complete resorption of a large, extruded cervical herniated disc in a symptomatic patient and a review of the literature on resorption of herniated discs. The review suggests that larger herniations with an epidural location (penetration of the posterior longitudinal ligament) have a greater chance of resorption.

  4. PREFACE: Hot Quarks 2012: Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions

    NASA Astrophysics Data System (ADS)

    Bleicher, Markus; Caines, Helen; Calderón de la Barca Sanchez, Manuel; Fries, Rainer; Granier de Cassagnac, Raphaël; Hippolyte, Boris; Mischke, André; Mócsy, Ágnes; Petersen, Hannah; Ruan, Lijuan; Salgado, Carlos A.

    2013-09-01

    The 5th edition of the Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions (Hot Quarks 2012) was held in Copamarina, Puerto Rico from 14-20 October 2012. As in previous years, this meeting gathered more than 70 participants in the early years of their scientific careers. This issue contains the proceedings of the workshop. As in the past, the Hot Quarks workshop offered a unique atmosphere for a lively discussion and interpretation of the current measurements from high energy nuclear collisions. Recent results and upgrades at CERN's Large Hadron Collider (LHC) and Brookhaven's Relativistic Heavy Ion Collider (RHIC) were presented. Measurements from the proton-led run at the CERN-LHC were shown for the first time at this meeting. Recent theoretical developments were also extensively discussed, as well as the proposals for future facilities such as the Facility for Antiproton and Ion Research (FAIR) at Darmstadt, the Electron-Ion Collider at Brookhaven, and the LHeC. The conference's goal to provide a platform for young researchers to learn and foster their interactions was successfully met. We wish to thank the sponsors of the Hot Quarks 2012 Conference, who supported the authors of this volume: Brookhaven National Laboratory (USA), European Laboratory for Particle Physics CERN (Switzerland), European Research Council (EU), ExtreMe Matter Institute EMMI (Germany), Helmholtz International Center for FAIR (Germany), IN2P3/CNRS (France) and the European Research Council via grant #259612, Lawrence Berkeley National Laboratory (USA), Lawrence Livermore National Laboratory (USA), Los Alamos National Laboratory (USA), National Science Foundation (USA), and Netherlands Organization for Scientific Research (Netherlands). Marcus BleicherAndré Mischke Goethe-University Frankfurt and HIC4FAIRUtrecht University and Nikhef Amsterdam GermanyThe Netherlands Helen CainesÁgnes Mócsy Yale UniversityPratt Institute and Brookhaven National

  5. PREFACE: Hot Quarks 2014: Workshop for young scientists on the physics of ultrarelativistic nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    2015-05-01

    The 6th edition of the Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions (Hot Quarks 2014) was held in Las Negras, Spain from 21-28 September 2014. Following the traditions of the conference, this meeting gathered more than 70 participants in the first years of their scientific careers. The present issue contains the proceedings of this workshop. As in the past, the Hot Quarks workshop offered a unique atmosphere for a lively discussion and interpretation of the current measurements from high energy nuclear collisions. Recent results and upgrades at CERN's Large Hadron Collider (LHC) and Brookhaven's Relativistic Heavy Ion Collider (RHIC) were presented. Recent theoretical developments were also extensively discussed as well as the perspectives for future facilities such as the Facility for Antiproton and Ion Research (FAIR) at Darmstadt and the Electron-Ion Collider at Brookhaven. The conference's goal to provide a platform for young researchers to learn and foster their interactions was successfully met. We wish to thank the sponsors of the Hot Quarks 2014 Conference, who supported the authors of this volume: Brookhaven National Laboratory (USA), CPAN (Spain), Czech Science Foundation (GACR) under grant 13-20841S (Czech Republic), European Laboratory for Particle Physics CERN (Switzerland), European Research Council under grant 259612 (EU), ExtreMe Matter Institute EMMI (Germany), Helmholtz Association and GSI under grant VH-NG-822, Helmholtz International Center for FAIR (Germany), National Science Foundation under grant No.1359622 (USA), Nuclear Physics Institute ASCR (Czech Republic), Patronato de la Alhambra y Generalife (Spain) and the Universidad de Granada (Spain). Javier López Albacete, Universidad de Granada (Spain) Jana Bielcikova, Nuclear Physics Inst. and Academy of Sciences (Czech Republic) Rainer J. Fries, Texas A&M University (USA) Raphaël Granier de Cassagnac, CNRS-IN2P3 and École polytechnique (France

  6. Nucleus fingerprinting for the unique identification of Feulgen-stained nuclei

    NASA Astrophysics Data System (ADS)

    Friedrich, David; Brozio, Matthias; Bell, André; Biesterfeld, Stefan; Böcking, Alfred; Aach, Til

    2012-03-01

    DNA Image Cytometry is a method for non-invasive cancer diagnosis which measures the DNA content of Feulgen-stained nuclei. DNA content is measured using a microscope system equipped with a digital camera as a densitometer and estimating the DNA content from the absorption of light when passing through the nuclei. However, a DNA Image Cytometry measurement is only valid if each nucleus is only measured once. To assist the user in preventing multiple measurements of the same nucleus, we have developed a unique digital identifier for the characterization of Feulgen-stained nuclei, the so called Nucleus Fingerprint. Only nuclei with a new fingerprint can be added to the measurement. This fingerprint is based on basic nucleus features, the contour of the nucleus and the spatial relationship to nuclei in the vicinity. Based on this characterization, a classifier for testing two nuclei for identity is presented. In a pairwise comparison of ~40000 pairs of mutually different nuclei, 99.5% were classified as different. In another 450 tests, the fingerprints of the same nucleus recorded a second time were in all cases judged identical. We therefore conclude that our Nucleus Fingerprint approach robustly prevents the repeated measurement of nuclei in DNA Image Cytometry.

  7. Kleptochloroplast Enlargement, Karyoklepty and the Distribution of the Cryptomonad Nucleus in Nusuttodinium (= Gymnodinium) aeruginosum (Dinophyceae).

    PubMed

    Onuma, Ryo; Horiguchi, Takeo

    2015-05-01

    The unarmoured freshwater dinoflagellate Nusuttodinium (= Gymnodinium) aeruginosum retains a cryptomonad-derived kleptochloroplast and nucleus, the former of which fills the bulk of its cell volume. The paucity of studies following morphological changes to the kleptochloroplast with time make it unclear how the kleptochloroplast enlarges and why the cell ultimately loses the cryptomonad nucleus. We observed, both at the light and electron microscope level, morphological changes to the kleptochloroplast incurred by the enlargement process under culture conditions. The distribution of the cryptomonad nucleus after host cell division was also investigated. The volume of the kleptochloroplast increased more than 20-fold, within 120h of ingestion of the cryptomonad. Host cell division was not preceded by cryptomonad karyokinesis so that only one of the daughter cells inherited a cryptomonad nucleus. The fate of all daughter cells originating from a single cell through five generations was closely monitored, and this observation revealed that the cell that inherited the cryptomonad nucleus consistently possessed the largest kleptochloroplast for that generation. Therefore, this study suggests that some important cryptomonad nucleus division mechanism is lost during ingestion process, and that the cryptomonad nucleus carries important information for the enlargement of the kleptochloroplast.

  8. Top-down-directed synchrony from medial frontal cortex to nucleus accumbens during reward anticipation.

    PubMed

    Cohen, Michael X; Bour, Lo; Mantione, Mariska; Figee, Martijn; Vink, Matthijs; Tijssen, Marina A J; van Rootselaar, Anne-Fleur; van den Munckhof, Pepijn; Schuurman, P Richard; Denys, Damiaan

    2012-01-01

    The nucleus accumbens and medial frontal cortex (MFC) are part of a loop involved in modulating behavior according to anticipated rewards. However, the precise temporal landscape of their electrophysiological interactions in humans remains unknown because it is not possible to record neural activity from the nucleus accumbens using noninvasive techniques. We recorded electrophysiological activity simultaneously from the nucleus accumbens and cortex (via surface EEG) in humans who had electrodes implanted as part of deep-brain-stimulation treatment for obsessive-compulsive disorder. Patients performed a simple reward motivation task previously shown to activate the ventral striatum. Spectral Granger causality analyses were applied to dissociate "top-down" (cortex → nucleus accumbens)- from "bottom-up" (nucleus accumbens → cortex)-directed synchronization (functional connectivity). "Top-down"-directed synchrony from cortex to nucleus accumbens was maximal over medial frontal sites and was significantly stronger when rewards were anticipated. These findings provide direct electrophysiological evidence for a role of the MFC in modulating nucleus accumbens reward-related processing and may be relevant to understanding the mechanisms of deep-brain stimulation and its beneficial effects on psychiatric conditions. PMID:21547982

  9. Squish and squeeze-the nucleus as a physical barrier during migration in confined environments.

    PubMed

    McGregor, Alexandra Lynn; Hsia, Chieh-Ren; Lammerding, Jan

    2016-06-01

    From embryonic development to cancer metastasis, cell migration plays a central role in health and disease. It is increasingly becoming apparent that cells migrating in three-dimensional (3-D) environments exhibit some striking differences compared with their well-established 2-D counterparts. One key finding is the significant role the nucleus plays during 3-D migration: when cells move in confined spaces, the cell body and nucleus must deform to squeeze through available spaces, and the deformability of the large and relatively rigid nucleus can become rate-limiting. In this review, we highlight recent findings regarding the role of nuclear mechanics in 3-D migration, including factors that govern nuclear deformability, and emerging mechanisms by which cells apply cytoskeletal forces to the nucleus to facilitate nuclear translocation. Intriguingly, the 'physical barrier' imposed by the nucleus also impacts cytoplasmic dynamics that affect cell migration and signaling, and changes in nuclear structure resulting from the mechanical forces acting on the nucleus during 3-D migration could further alter cellular function. These findings have broad relevance to the migration of both normal and cancerous cells inside living tissues, and motivate further research into the molecular details by which cells move their nuclei, as well as the consequences of the mechanical stress on the nucleus.

  10. Kleptochloroplast Enlargement, Karyoklepty and the Distribution of the Cryptomonad Nucleus in Nusuttodinium (= Gymnodinium) aeruginosum (Dinophyceae).

    PubMed

    Onuma, Ryo; Horiguchi, Takeo

    2015-05-01

    The unarmoured freshwater dinoflagellate Nusuttodinium (= Gymnodinium) aeruginosum retains a cryptomonad-derived kleptochloroplast and nucleus, the former of which fills the bulk of its cell volume. The paucity of studies following morphological changes to the kleptochloroplast with time make it unclear how the kleptochloroplast enlarges and why the cell ultimately loses the cryptomonad nucleus. We observed, both at the light and electron microscope level, morphological changes to the kleptochloroplast incurred by the enlargement process under culture conditions. The distribution of the cryptomonad nucleus after host cell division was also investigated. The volume of the kleptochloroplast increased more than 20-fold, within 120h of ingestion of the cryptomonad. Host cell division was not preceded by cryptomonad karyokinesis so that only one of the daughter cells inherited a cryptomonad nucleus. The fate of all daughter cells originating from a single cell through five generations was closely monitored, and this observation revealed that the cell that inherited the cryptomonad nucleus consistently possessed the largest kleptochloroplast for that generation. Therefore, this study suggests that some important cryptomonad nucleus division mechanism is lost during ingestion process, and that the cryptomonad nucleus carries important information for the enlargement of the kleptochloroplast. PMID:25771111

  11. Age-related structural and functional changes in the cochlear nucleus.

    PubMed

    Frisina, Robert D; Walton, Joseph P

    2006-01-01

    Presbycusis - age-related hearing loss - is a key communication disorder and chronic medical condition of our aged population. The cochlear nucleus is the major site of projections from the auditory portion of the inner ear. Relative to other levels of the peripheral and central auditory systems, relatively few studies have been conducted examining age-related changes in the cochlear nucleus. The neurophysiological investigations suggest declines in glycine-mediated inhibition, reflected in increased firing rates in cochlear nucleus neurons from old animals relative to young adults. Biochemical investigations of glycine inhibition in the cochlear nucleus are consistent with the functional aging declines of this inhibitory neurotransmitter system that affect complex sound processing. Anatomical reductions in neurons of the cochlear nucleus and their output pathways can occur due to aging changes in the brain, as well as due to age-dependent plasticity of the cochlear nucleus in response to the age-related loss of inputs from the cochlea, particularly from the basal, high-frequency regions. Novel preventative and curative biomedical interventions in the future aimed at alleviating the hearing loss that comes with age, will likely emanate from increasing our knowledge and understanding of its neural and molecular bases. To the extent that this sensory deficit resides in the central auditory system, including the cochlear nucleus, future neural therapies will be able to improve hearing in the elderly.

  12. Central pupillary light reflex circuits in the cat: I. The olivary pretectal nucleus.

    PubMed

    Sun, Wensi; May, Paul J

    2014-12-15

    The central pathways subserving the feline pupillary light reflex were examined by defining retinal input to the olivary pretectal nucleus (OPt), the midbrain projections of this nucleus, and the premotor neurons within it. Unilateral intravitreal wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) injections revealed differences in the pattern of retinal OPt termination on the two sides. Injections of WGA-HRP into OPt labeled terminals bilaterally in the anteromedian nucleus, and to a lesser extent in the supraoculomotor area, centrally projecting Edinger-Westphal nucleus, and nucleus of the posterior commissure. Labeled terminals, as well as retrogradely labeled multipolar cells, were present in the contralateral OPt, indicating a commissural pathway. Injections of WGA-HRP into the anteromedian nucleus labeled fusiform premotor neurons within the OPt, as well as multipolar cells in the nucleus of the posterior commissure. Connections between retinal terminals and the pretectal premotor neurons were characterized by combining vitreous chamber and anteromedian nucleus injections of WGA-HRP in the same animal. Fusiform-shaped, retrogradely labeled cells fell within the anterogradely labeled retinal terminal field in the OPt. Ultrastructural analysis revealed labeled retinal terminals containing clear spherical vesicles. They contacted labeled pretectal premotor neurons via asymmetric synaptic densities. These results provide an anatomical substrate for the pupillary light reflex in the cat. Pretectal premotor neurons receive direct retinal input via synapses suggestive of an excitatory drive, and project directly to nuclei containing preganglionic motoneurons. These projections are concentrated in the anteromedian nucleus, indicating its involvement in the pupillary light reflex.

  13. Volumetric studies on the red nucleus of the rat at different ages.

    PubMed

    Boseila, A W; Hashem, S M; Badawy, Y H

    1975-01-01

    The postnatal development of the red nucleus in albino rat was quantitatively studied. Planimetric studies on stained paraffin sections of the midbrain showed that the red nucleus has a rounded contour with tapering ends and a broad centre. The volume of the red nucleus revealed an increase from birth, to reach its maximum at the age of 3 months, then declines until the age of 2 years. However, the size does not regain its newly born value. On the other hand, the number of cells remains constant during the entire life span of the animal.

  14. The subthalamic nucleus exerts opposite control on cocaine and 'natural' rewards.

    PubMed

    Baunez, Christelle; Dias, Carine; Cador, Martine; Amalric, Marianne

    2005-04-01

    A challenge in treating drug addicts is preventing their pathological motivation for the drug without impairing their general affective state toward natural reinforcers. Here we have shown that discrete lesions of the subthalamic nucleus greatly decreased the motivation of rats for cocaine while increasing it for food reward. The subthalamic nucleus, a key structure controlling basal ganglia outputs, is therefore able to oppositely modulate the effect of 'natural' rewards and drugs of abuse on behavior. Modulating the activity of the subthalamic nucleus might prove to be a new target for the treatment of cocaine addiction. PMID:15793577

  15. Cytoplasmic intermediate filaments mediate actin-driven positioning of the nucleus.

    PubMed

    Dupin, Isabelle; Sakamoto, Yasuhisa; Etienne-Manneville, Sandrine

    2011-03-15

    The localization of the nucleus is precisely regulated, and defects in nuclear positioning are observed in diseases such as lissencephaly, cerebellar ataxia and dysplasia. We show here that cytoplasmic intermediate filaments are essential players in actin-dependent positioning of the nucleus. The actin retrograde flow is relayed by a flow of intermediate filaments that accumulate asymmetrically around the nuclear envelope. Perturbations of the intermediate filament network alter positioning of the nucleus in both migrating and immobile astrocytes. This function of intermediate filaments might be crucial for regulating cell motility, in particular in tumor cells expressing high levels of cytoplasmic intermediate filaments.

  16. State-dependent control of breathing by the retrotrapezoid nucleus

    PubMed Central

    Burke, Peter GR; Kanbar, Roy; Basting, Tyler M; Hodges, Walter M; Viar, Kenneth E; Stornetta, Ruth L; Guyenet, Patrice G

    2015-01-01

    Key points This study explores the state dependence of the hypercapnic ventilatory reflex (HCVR). We simulated an instantaneous increase or decrease of central chemoreceptor activity by activating or inhibiting the retrotrapezoid nucleus (RTN) by optogenetics in conscious rats. During quiet wake or non-REM sleep, hypercapnia increased both breathing frequency (fR) and tidal volume (VT) whereas, in REM sleep, hypercapnia increased VT exclusively. Optogenetic inhibition of RTN reduced VT in all sleep–wake states, but reduced fR only during quiet wake and non-REM sleep. RTN stimulation always increased VT but raised fR only in quiet wake and non-REM sleep. Phasic RTN stimulation produced active expiration and reduced early expiratory airflow (i.e. increased upper airway resistance) only during wake. We conclude that the HCVR is highly state-dependent. The HCVR is reduced during REM sleep because fR is no longer under chemoreceptor control and thus could explain why central sleep apnoea is less frequent in REM sleep. Abstract Breathing has different characteristics during quiet wake, non-REM or REM sleep, including variable dependence on . We investigated whether the retrotrapezoid nucleus (RTN), a proton-sensitive structure that mediates a large portion of the hypercapnic ventilatory reflex, regulates breathing differently during sleep vs. wake. Electroencephalogram, neck electromyogram, blood pressure, respiratory frequency (fR) and tidal volume (VT) were recorded in 28 conscious adult male Sprague–Dawley rats. Optogenetic stimulation of RTN with channelrhodopsin-2, or inhibition with archaerhodopsin, simulated an instantaneous increase or decrease of central chemoreceptor activity. Both opsins were delivered with PRSX8-promoter-containing lentiviral vectors. RTN and catecholaminergic neurons were transduced. During quiet wake or non-REM sleep, hypercapnia (3 or 6% ) increased both fR and VT whereas, in REM sleep, hypercapnia increased VT exclusively. RTN

  17. Dynamics of abducens nucleus neurons in the awake mouse

    PubMed Central

    Thumser, Zachary C.

    2012-01-01

    The mechanics of the eyeball and orbital tissues (the “ocular motor plant”) are a fundamental determinant of ocular motor signal processing. The mouse is used increasingly in ocular motor physiology, but little is known about its plant mechanics. One way to characterize the mechanics is to determine relationships between extraocular motoneuron firing and eye movement. We recorded abducens nucleus neurons in mice executing compensatory eye movements during 0.1- to 1.6-Hz oscillation in the light. We analyzed firing rates to extract eye position and eye velocity sensitivities, from which we determined time constants of a viscoelastic model of the plant. The majority of abducens neurons were already active with the eye in its central rest position, with only 6% recruited at more abducted positions. Firing rates exhibited largely linear relationships to eye movement, although there was a nonlinearity consisting of increasing modulation in proportion to eye movement as eye amplitudes became small (due to reduced stimulus amplitude or reduced alertness). Eye position and velocity sensitivities changed with stimulus frequency as expected for an ocular motor plant dominated by cascaded viscoelasticities. Transfer function poles lay at approximately 0.1 and 0.9 s. Compared with previously studied animal species, the mouse plant is stiffer than the rabbit but laxer than cat and rhesus. Differences between mouse and rabbit can be explained by scaling for eye size (allometry). Differences between the mouse and cat or rhesus can be explained by differing ocular motor repertoires of animals with and without a fovea or area centralis. PMID:22896719

  18. HUBBLE DETECTION OF COMET NUCLEUS AT FRINGE OF SOLAR SYSTEM

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is sample data from NASA's Hubble Space Telescope that illustrates the detection of comets in the Kuiper Belt, a region of space beyond the orbit of the planet Neptune. This pair of images, taken with the Wide Field Planetary Camera 2 (WFPC2), shows one of the candidate Kuiper Belt objects found with Hubble. Believed to be an icy comet nucleus several miles across, the object is so distant and faint that Hubble's search is the equivalent of finding the proverbial needle-in-haystack. Each photo is a 5-hour exposure of a piece of sky carefully selected such that it is nearly devoid of background stars and galaxies that could mask the elusive comet. The left image, taken on August 22, 1994, shows the candidate comet object (inside circle) embedded in the background. The right picture, take of the same region one hour forty-five minutes later shows the object has apparently moved in the predicted direction and rate of motion for a kuiper belt member. The dotted line on the images is a possible orbit that this Kuiper belt comet is following. A star (lower right corner) and a galaxy (upper right corner) provide a static background reference. In addition, other objects in the picture have not moved during this time, indicating they are outside our solar system. Through this search technique astronomers have identified 29 candidate comet nuclei belonging to an estimated population of 200 million particles orbiting the edge of our solar system. The Kupier Belt was theorized 40 years ago, and its larger members detected several years ago. However, Hubble has found the underlying population of normal comet-sized bodies. Credit: A. Cochran (University of Texas) and NASA

  19. Computational modeling of pedunculopontine nucleus deep brain stimulation

    NASA Astrophysics Data System (ADS)

    Zitella, Laura M.; Mohsenian, Kevin; Pahwa, Mrinal; Gloeckner, Cory; Johnson, Matthew D.

    2013-08-01

    Objective. Deep brain stimulation (DBS) near the pedunculopontine nucleus (PPN) has been posited to improve medication-intractable gait and balance problems in patients with Parkinson's disease. However, clinical studies evaluating this DBS target have not demonstrated consistent therapeutic effects, with several studies reporting the emergence of paresthesia and oculomotor side effects. The spatial and pathway-specific extent to which brainstem regions are modulated during PPN-DBS is not well understood. Approach. Here, we describe two computational models that estimate the direct effects of DBS in the PPN region for human and translational non-human primate (NHP) studies. The three-dimensional models were constructed from segmented histological images from each species, multi-compartment neuron models and inhomogeneous finite element models of the voltage distribution in the brainstem during DBS. Main Results. The computational models predicted that: (1) the majority of PPN neurons are activated with -3 V monopolar cathodic stimulation; (2) surgical targeting errors of as little as 1 mm in both species decrement activation selectivity; (3) specifically, monopolar stimulation in caudal, medial, or anterior PPN activates a significant proportion of the superior cerebellar peduncle (up to 60% in the human model and 90% in the NHP model at -3 V) (4) monopolar stimulation in rostral, lateral or anterior PPN activates a large percentage of medial lemniscus fibers (up to 33% in the human model and 40% in the NHP model at -3 V) and (5) the current clinical cylindrical electrode design is suboptimal for isolating the modulatory effects to PPN neurons. Significance. We show that a DBS lead design with radially-segmented electrodes may yield improved functional outcome for PPN-DBS.

  20. Role of amygdala central nucleus in feature negative discriminations

    PubMed Central

    Holland, Peter C.

    2012-01-01

    Consistent with a popular theory of associative learning, the Pearce-Hall (1980) model, the surprising omission of expected events enhances cue associability (the ease with which a cue may enter into new associations), across a wide variety of behavioral training procedures. Furthermore, previous experiments from this laboratory showed that these enhancements are absent in rats with impaired function of the amygdala central nucleus (CeA). A notable exception to these assertions is found in feature negative (FN) discrimination learning, in which a “target” stimulus is reinforced when it is presented alone but nonreinforced when it is presented in compound with another, “feature” stimulus. According to the Pearce-Hall model, reinforcer omission on compound trials should enhance the associability of the feature relative to control training conditions. However, prior experiments have shown no evidence that CeA lesions affect FN discrimination learning. Here we explored this apparent contradiction by evaluating the hypothesis that the surprising omission of an event confers enhanced associability on a cue only if that cue itself generates the disconfirmed prediction. Thus, in a FN discrimination, the surprising omission of the reinforcer on compound trials would enhance the associability of the target stimulus but not that of the feature. Our data confirmed this hypothesis, and showed this enhancement to depend on intact CeA function, as in other procedures. The results are consistent with modern reformulations of both cue and reward processing theories that assign roles for both individual and aggregate error terms in associative learning. PMID:22889308

  1. Nucleus incertus Orexin2 receptors mediate alcohol seeking in rats.

    PubMed

    Kastman, Hanna E; Blasiak, Anna; Walker, Leigh; Siwiec, Marcin; Krstew, Elena V; Gundlach, Andrew L; Lawrence, Andrew J

    2016-11-01

    Alcoholism is a chronic relapsing disorder and a major global health problem. Stress is a key precipitant of relapse in human alcoholics and in animal models of alcohol seeking. The brainstem nucleus incertus (NI) contains a population of relaxin-3 neurons that are highly responsive to psychological stressors; and the ascending NI relaxin-3/RXFP3 signalling system is implicated in stress-induced reinstatement of alcohol seeking. The NI receives orexinergic innervation and expresses orexin1 (OX1) and orexin2 (OX2) receptor mRNA. In alcohol-preferring (iP) rats, we examined the impact of yohimbine-induced reinstatement of alcohol seeking on orexin neuronal activation, and the effect of bilateral injections into NI of the OX1 receptor antagonist, SB-334867 (n = 16) or the OX2 receptor antagonist, TCS-OX2-29 (n = 8) on stress-induced reinstatement of alcohol seeking. We also assessed the effects of orexin-A on NI neuronal activity and the involvement of OX1 and OX2 receptors using whole cell patch-clamp recordings in rat brain slices. Yohimbine-induced reinstatement of alcohol seeking activated orexin neurons. Bilateral NI injections of TCS-OX2-29 attenuated yohimbine-induced reinstatement of alcohol seeking. In contrast, intra-NI injection of SB-334867 had no significant effect. In line with these data, orexin-A (600 nM) depolarized a majority of NI neurons recorded in coronal brain slices (18/28 cells), effects prevented by bath application of TCS-OX2-29 (10 μM), but not SB-334867 (10 μM). These data suggest an excitatory orexinergic input to NI contributes to yohimbine-induced reinstatement of alcohol seeking, predominantly via OX2 receptor signalling. PMID:27395787

  2. Histone arginine methylation in cocaine action in the nucleus accumbens.

    PubMed

    Damez-Werno, Diane M; Sun, HaoSheng; Scobie, Kimberly N; Shao, Ningyi; Rabkin, Jaclyn; Dias, Caroline; Calipari, Erin S; Maze, Ian; Pena, Catherine J; Walker, Deena M; Cahill, Michael E; Chandra, Ramesh; Gancarz, Amy; Mouzon, Ezekiell; Landry, Joseph A; Cates, Hannah; Lobo, Mary-Kay; Dietz, David; Allis, C David; Guccione, Ernesto; Turecki, Gustavo; Defilippi, Paola; Neve, Rachael L; Hurd, Yasmin L; Shen, Li; Nestler, Eric J

    2016-08-23

    Repeated cocaine exposure regulates transcriptional regulation within the nucleus accumbens (NAc), and epigenetic mechanisms-such as histone acetylation and methylation on Lys residues-have been linked to these lasting actions of cocaine. In contrast to Lys methylation, the role of histone Arg (R) methylation remains underexplored in addiction models. Here we show that protein-R-methyltransferase-6 (PRMT6) and its associated histone mark, asymmetric dimethylation of R2 on histone H3 (H3R2me2a), are decreased in the NAc of mice and rats after repeated cocaine exposure, including self-administration, and in the NAc of cocaine-addicted humans. Such PRMT6 down-regulation occurs selectively in NAc medium spiny neurons (MSNs) expressing dopamine D2 receptors (D2-MSNs), with opposite regulation occurring in D1-MSNs, and serves to protect against cocaine-induced addictive-like behavioral abnormalities. Using ChIP-seq, we identified Src kinase signaling inhibitor 1 (Srcin1; also referred to as p140Cap) as a key gene target for reduced H3R2me2a binding, and found that consequent Srcin1 induction in the NAc decreases Src signaling, cocaine reward, and the motivation to self-administer cocaine. Taken together, these findings suggest that suppression of Src signaling in NAc D2-MSNs, via PRMT6 and H3R2me2a down-regulation, functions as a homeostatic brake to restrain cocaine action, and provide novel candidates for the development of treatments for cocaine addiction. PMID:27506785

  3. Rapid feedback processing in human nucleus accumbens and motor thalamus.

    PubMed

    Schüller, Thomas; Gruendler, Theo O J; Jocham, Gerhard; Klein, Tilmann A; Timmermann, Lars; Visser-Vandewalle, Veerle; Kuhn, Jens; Ullsperger, Markus

    2015-04-01

    The nucleus accumbens (NAcc) and thalamus are integral parts in models of feedback processing. Deep brain stimulation (DBS) has been successfully employed to alleviate symptoms of psychiatric conditions including obsessive-compulsive disorder (OCD) and Tourette's syndrome (TS). Common target structures are the NAcc and the ventral anterior and ventro-lateral nuclei (VA/VL) of the thalamus, for OCD and TS, respectively. The feedback related negativity (FRN) is an event-related potential associated with feedback processing reflecting posterior medial frontal cortex (pMFC) activity. Here we report on three cases where we recorded scalp EEG and local field potentials (LFP) from externalized electrodes located in the NAcc or thalamus (VA/VL) while patients engaged in a modified time estimation task, known to engage feedback processing and elicit the FRN. Additionally, scalp EEG were recorded from 29 healthy participants (HP) engaged in the same task. The signal in all structures (pMFC, NAcc, and thalamus) was differently modulated by positive and negative feedback. LFP activity in the NAcc showed a biphasic time course after positive feedback during the FRN time interval. Negative feedback elicited a much weaker and later response. In the thalamus a monophasic modulation was recorded during the FRN time interval. Again, this modulation was more pronounced after positive performance feedback compared to negative feedback. In channels outside the target area no modulation was observed. The surface-FRN was reliably elicited on a group level in HP and showed no significant difference following negative feedback between patients and HP. German Clinical Trial Register: Neurocognitive specification of dysfunctions within basal ganglia-cortex loops and their therapeutic modulation by deep brain stimulation in patients with obsessive compulsive disorder and Tourette syndrome, http://www.drks.de/DRKS00005316. PMID:25726897

  4. Nucleus pulposus cell-matrix interactions with laminins.

    PubMed

    Gilchrist, C L; Francisco, A T; Plopper, G E; Chen, J; Setton, L A

    2011-01-01

    The cells of the nucleus pulposus (NP) region of the intervertebral disc play a critical role in this tissue's generation and maintenance, and alterations in NP cell viability, metabolism, and phenotype with aging may be key contributors to progressive disc degeneration. Relatively little is understood about the phenotype of NP cells, including their cell-matrix interactions which may modulate phenotype and survival. Our previous work has identified strong and region-specific expression of laminins and laminin cell-surface receptors in immature NP tissues, suggesting laminin cell-matrix interactions are uniquely important to the biology of NP cells. Whether these observed tissue-level laminin expression patterns reflect functional adhesion behaviors for these cells is not known. In this study, we examined NP cell-matrix interactions with specific matrix ligands, including various laminin isoforms, using quantitative assays of cell attachment, spreading, and adhesion strength. NP cells were found to attach in higher numbers and exhibited rapid cell spreading and higher resistance to detachment force on two laminin isoforms (LM-511,LM-332) identified to be uniquely expressed in the NP region, as compared to another laminin isoform (LM-111) and several other matrix ligands (collagen, fibronectin). Additionally, NP cells were found to attach in higher numbers to laminins as compared to cells isolated from the disc's annulus fibrosus region. These findings confirm that laminin and laminin receptor expression documented in NP tissues translates into unique functional NP cell adhesion behaviors that may be useful tools for in vitro cell culture and biomaterials that support NP cells.

  5. Modulation of hypothalamic arcuate nucleus on gastric motility in rats

    PubMed Central

    Xu, Guang-Yao; Ma, Rong; Cao, Qi; Su, Bao-Tian

    1998-01-01

    AIM: To investigate whether the arcuate nucleus (ARC) could modulate gastric motility, and if so, what are the mechanisms or pathways. METHODS: Wistar rats, anaesthetized with urethan, parameters of stimulation and electrolytic lesion sites were determined according to the Paxinos and Watson “ATLAS of rat brain in steriotaxic coordinate”. Intragastric pressure ( IGP ) and gastric motility were measured by Reybould¡äs method. RESULTS: Electrical stimulation of ARC could obviously decrease the IGP by 42.2% ± 5.4%, n = 15, P < 0.01, and the phasic gastric contractions disappeared. The analysis showed that the locus coeruleus (LC) and dorsal raphe (DR) nuclei may be involved in central, but without the invovement of β-endorphinergic neurons rich in the ARC, while in periphery, the peripheral neural pathways are both vagus and sympathetic nerves. The fibers in vagus may be non-cholinergic. Humoral factors may also be involved. At the receptor level, Tonic action of adrenergic nerve in the stomach is mainly inhibitory; β-receptors, which may be present on the stomach wall and mediate inhibition; and α-receptors, which come into play through vagus, mediate inhibition, but those present on the smooth muscle mediate sympathetic excitation. Microinjection of TRH into ARC could significantly increase the IGP by 183.02% (0.53 kPa ± 0.08 kPa vs 1.5 kPa ± 0.6 kPa, n = 10, P < 0.001), the rate and amplitude of phasic gastric contraction were also increased (3 cpm vs 6 cpm-8 cpm). The peripheral pathway of such excitatory effects were transmitted with cholinergic vagus nerve mediated by M-receptor. CONCLUSION: ARC could modulate gastric motility biphasically, inhibitory and excitatory, depending on the nature of stimuli. PMID:11819337

  6. Hypoxia silences retrotrapezoid nucleus respiratory chemoreceptors via alkalosis.

    PubMed

    Basting, Tyler M; Burke, Peter G R; Kanbar, Roy; Viar, Kenneth E; Stornetta, Daniel S; Stornetta, Ruth L; Guyenet, Patrice G

    2015-01-14

    In conscious mammals, hypoxia or hypercapnia stimulates breathing while theoretically exerting opposite effects on central respiratory chemoreceptors (CRCs). We tested this theory by examining how hypoxia and hypercapnia change the activity of the retrotrapezoid nucleus (RTN), a putative CRC and chemoreflex integrator. Archaerhodopsin-(Arch)-transduced RTN neurons were reversibly silenced by light in anesthetized rats. We bilaterally transduced RTN and nearby C1 neurons with Arch (PRSx8-ArchT-EYFP-LVV) and measured the cardiorespiratory consequences of Arch activation (10 s) in conscious rats during normoxia, hypoxia, or hyperoxia. RTN photoinhibition reduced breathing equally during non-REM sleep and quiet wake. Compared with normoxia, the breathing frequency reduction (Δf(R)) was larger in hyperoxia (65% FiO2), smaller in 15% FiO2, and absent in 12% FiO2. Tidal volume changes (ΔV(T)) followed the same trend. The effect of hypoxia on Δf(R) was not arousal-dependent but was reversed by reacidifying the blood (acetazolamide; 3% FiCO2). Δf(R) was highly correlated with arterial pH up to arterial pH (pHa) 7.5 with no frequency inhibition occurring above pHa 7.53. Blood pressure was minimally reduced suggesting that C1 neurons were very modestly inhibited. In conclusion, RTN neurons regulate eupneic breathing about equally during both sleep and wake. RTN neurons are the first putative CRCs demonstrably silenced by hypocapnic hypoxia in conscious mammals. RTN neurons are silent above pHa 7.5 and increasingly active below this value. During hyperoxia, RTN activation maintains breathing despite the inactivity of the carotid bodies. Finally, during hypocapnic hypoxia, carotid body stimulation increases breathing frequency via pathways that bypass RTN.

  7. GABAergic mechanisms of the lateral parabrachial nucleus on sodium appetite.

    PubMed

    de Oliveira, Lisandra B; Callera, João C; De Luca, Laurival A; Colombari, Débora S A; Menani, José V

    2007-07-12

    GABAergic activation in the lateral parabrachial nucleus (LPBN) induces sodium and water intake in satiated and normovolemic rats. In the present study we investigated the effects of GABAA receptor activation in the LPBN on 0.3M NaCl, water, 2% sucrose and food intake in rats submitted to sodium depletion (treatment with the diuretic furosemide subcutaneously+sodium deficient food for 24h), 24h food deprivation or 24 h water deprivation. Male Holtzman rats with bilateral stainless steel cannulas implanted into the LPBN were used. In sodium depleted rats, muscimol (GABAA receptor agonist, 0.5 nmol/0.2 microl), bilaterally injected into the LPBN, produced an inconsistent increase of water intake and two opposite effects on 0.3M NaCl intake: an early inhibition (4.3+/-2.7 versus saline: 14.4+/-1.0 ml/15 min) and a late facilitation (37.6+/-2.7 versus saline: 21.1+/-0.9 ml/180 min). The pretreatment of the LPBN with bicuculline (GABAA receptor antagonist, 1.6 nmol) abolished these effects of muscimol. Muscimol into the LPBN also reduced food deprivation-induced food intake in the first 30 min of test (1.7+/-0.6g versus saline: 4.1+/-0.6g), without changing water deprivation-induced water intake or 2% sucrose intake in sodium depleted rats. Therefore, although GABAA receptors in the LPBN are not tonically involved in the control of sodium depletion-induced sodium intake, GABAA receptor activation in the LPBN produces an early inhibition and a late facilitation of sodium depletion-induced sodium intake. GABAA activation in the LPBN also inhibits food intake, while it consistently increases only sodium intake and not water, food or sucrose intake.

  8. Functional anatomy of subthalamic nucleus stimulation in Parkinson disease

    PubMed Central

    Eisenstein, Sarah A.; Koller, Jonathan M.; Black, Kathleen D.; Campbell, Meghan C.; Lugar, Heather M.; Ushe, Mwiza; Tabbal, Samer D.; Karimi, Morvarid; Hershey, Tamara; Perlmutter, Joel S.; Black, Kevin J.

    2014-01-01

    Objective We developed a novel method to map behavioral effects of deep brain stimulation (DBS) across a 3D brain region and to assign statistical significance after stringent Type I error correction. This method was applied to behavioral changes in Parkinson disease (PD) induced by subthalamic nucleus (STN) DBS to determine whether these responses depended on anatomical location of DBS. Method Fifty-one PD participants with STN DBS were evaluated off medication, with DBS off and during unilateral STN DBS with clinically optimized settings. Dependent variables included DBS-induced changes in Unified Parkinson Disease Rating Scale (UPDRS) subscores, kinematic measures of bradykinesia and rigidity, working memory, response inhibition, mood, anxiety, and akathisia. Weighted t-tests at each voxel produced p images showing where DBS most significantly affected each dependent variable based on outcomes of participants with nearby DBS. Finally, a permutation test computed the probability that this p image indicated significantly different responses based on stimulation site. Results Most motor variables improved with DBS anywhere in the STN region, but several motor, cognitive and affective responses significantly depended on precise location stimulated, with peak p values in superior STN/zona incerta (quantified bradykinesia), dorsal STN (mood, anxiety), and inferior STN/substantia nigra (UPDRS tremor, working memory). Interpretation Our method identified DBS-induced behavioral changes that depended significantly on DBS site. These results do not support complete functional segregation within STN, since movement improved with DBS throughout, and mood improved with dorsal STN DBS. Rather, findings support functional convergence of motor, cognitive and limbic information in STN. PMID:24953991

  9. Estimated Radiation on Mars, Hits per Cell Nucleus

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This global map of Mars shows estimates for amounts of high-energy-particle cosmic radiation reaching the surface, a serious health concern for any future human exploration of the planet.

    The estimates are based on cosmic-radiation measurements made on the way to Mars by the Mars radiation environment experiment, an instrument on NASA's 2001 Mars Odyssey spacecraft, plus information about Mars' surface elevations from the laser altimeter instrument on NASA's Mars Global Surveyor. The areas of Mars expected to have least radiation are where elevation is lowest, because those areas have more atmosphere above them to block out some of the radiation. Earth's thick atmosphere shields us from most cosmic radiation, but Mars has a much thinner atmosphere than Earth does.

    Colors in the map refer to the estimated average number of times per year each cell nucleus in a human there would be hit by a high-energy cosmic ray particle. The range is generally from two hits (color-coded green), a moderate risk level, to eight hits (coded red), a high risk level.

    NASA's Jet Propulsion Laboratory, Pasadena, Calif. manages the 2001 Mars Odyssey and Mars Global Surveyor missions for NASA's Office of Space Science, Washington D.C. The Mars radiation environment experiment was developed by NASA's Johnson Space Center. Lockheed Martin Astronautics, Denver, is the prime contractor for Odyssey, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. Modulation of cardiorespiratory function mediated by the paraventricular nucleus

    PubMed Central

    Kc, Prabha; Dick, Thomas E.

    2010-01-01

    The hypothalamic paraventricular nucleus (PVN) coordinates autonomic and neuroendocrine systems to maintain homeostasis and to respond to stress. Neuroanatomic and neurophysiologic experiments have provided insight into the mechanisms by which the PVN acts. The PVN projects directly to the spinal cord and brainstem and, specifically, to sites that control cardiorespiratory function: the intermediolateral cell columns and phrenic motor nuclei in the spinal cord and rostral ventrolateral medulla (RVLM) and the rostral nuclei in the ventral respiratory column (rVRC) in the brainstem. Activation of the PVN increases ventilation (both tidal volume and frequency) and blood pressure (both heart rate and sympathetic nerve activity). Excitatory and inhibitory neurotransmitters including glutamate and GABA converge in the PVN to influence its neuronal activity. However, a tonic GABAergic input to the PVN directly modulates excitatory outflow from the PVN. Further, even within the PVN, microinjection of GABAA receptor blockers increases glutamate release suggesting an indirect mechanism by which GABA control contributes to PVN functions. PVN activity alters blood pressure and ventilation during various stresses, such as maternal separation, chronic intermittent hypoxia (CIH), dehydration and hemorrhage. Among the several PVN neurotransmitters and neurohormones, vasopressin and oxytocin modulate ventilation and blood pressure. Here, we review our data indicating that increases in vasopressin and vasopressin type 1A (V1A) receptor signaling in the RVLM and rVRC are mechanisms increasing blood pressure and ventilation after exposure to CIH. That blockade of V1A receptors in the medulla normalizes baseline blood pressure as well as blunts PVN-evoked blood pressure and ventilatory responses in CIH-conditioned animals indicate the role of vasopressin in cardiorespiratory control. In summary, morphological and functional studies have found that the PVN integrates sensory input and

  11. Encoding of aversion by dopamine and the nucleus accumbens.

    PubMed

    McCutcheon, James E; Ebner, Stephanie R; Loriaux, Amy L; Roitman, Mitchell F

    2012-01-01

    Adaptive motivated behavior requires rapid discrimination between beneficial and harmful stimuli. Such discrimination leads to the generation of either an approach or rejection response, as appropriate, and enables organisms to maximize reward and minimize punishment. Classically, the nucleus accumbens (NAc) and the dopamine projection to it are considered an integral part of the brain's reward circuit, i.e., they direct approach and consumption behaviors and underlie positive reinforcement. This reward-centered framing ignores important evidence about the role of this system in encoding aversive events. One reason for bias toward reward is the difficulty in designing experiments in which animals repeatedly experience punishments; another is the challenge in dissociating the response to an aversive stimulus itself from the reward/relief experienced when an aversive stimulus is terminated. Here, we review studies that employ techniques with sufficient time resolution to measure responses in ventral tegmental area and NAc to aversive stimuli as they are delivered. We also present novel findings showing that the same stimulus - intra-oral infusion of sucrose - has differing effects on NAc shell dopamine release depending on the prior experience. Here, for some rats, sucrose was rendered aversive by explicitly pairing it with malaise in a conditioned taste aversion paradigm. Thereafter, sucrose infusions led to a suppression of dopamine with a similar magnitude and time course to intra-oral infusions of a bitter quinine solution. The results are discussed in the context of regional differences in dopamine signaling and the implications of a pause in phasic dopamine release within the NAc shell. Together with our data, the emerging literature suggests an important role for differential phasic dopamine signaling in aversion vs. reward. PMID:23055953

  12. Cometary activity and nucleus modelling: a new approach

    NASA Astrophysics Data System (ADS)

    Möhlmann, D.

    1996-06-01

    The phenomena of comet splittings with an average frequency of about one splitting per 100 years and comet (Chen and Jewitt, Icarus108, 265-271, 1994), and the restriction of cometary activity to well-defined small areas at the almost passive and mantle covered surface (Keller et al., ESA SP-250, Vol. II, pp. 363-364, 1986) are at present driving challenges to models of structure and evolution of comet nuclei. Extending the presently discussed models by incorporating lateral subsurface transport of sublimed volatiles, there appears the possibility that the places of sublimation are different from those of activity (the so-called active areas). Then, there is no necessity to distinguish between different surface properties at active and passive areas, assuming, e.g. an uncovered icy surface at active areas. Active areas are simply the very local "source sites" where the accumulated subsurface flows from distant regions reach the surface. The pressure driven subsurface flows of volatiles may not only leave the comet at its surface, they may penetrate via cracks, etc. also deeply into the nucleus. There they can cause a further growth of cracks and also new cracks. This can be a cause for the observed regular splittings. Furthermore, actual models (Kührt and Keller, Icarus109, 121-132, 1994; Skorov and Rickman, Planet. Space Sci.43, 1587-1594, 1995) of the gas transport through porous comet surface crusts can be interpreted as to give first indications for thermodynamical parameters in heat conducting and porous cometary crusts which are appropriate for 1 AU conditions to permit the temporary existence of a layer with fluid subsurface water within these crusts. This exciting result of the possible temporary existence of subsurface warm water in comets which approach the Sun within about 1 AU makes a cometary subsurface chemistry much more efficient than expected hitherto.

  13. Cannabinoid receptor 1-expressing neurons in the nucleus accumbens.

    PubMed

    Winters, Bradley D; Krüger, Juliane M; Huang, Xiaojie; Gallaher, Zachary R; Ishikawa, Masago; Czaja, Krzysztof; Krueger, James M; Huang, Yanhua H; Schlüter, Oliver M; Dong, Yan

    2012-10-01

    Endocannabinoid signaling critically regulates emotional and motivational states via activation of cannabinoid receptor 1 (CB1) in the brain. The nucleus accumbens (NAc) functions to gate emotional and motivational responses. Although expression of CB1 in the NAc is low, manipulation of CB1 signaling within the NAc triggers robust emotional/motivational alterations related to drug addiction and other psychiatric disorders, and these effects cannot be exclusively attributed to CB1 located at afferents to the NAc. Rather, CB1-expressing neurons in the NAc, although sparse, appear to be critical for emotional and motivational responses. However, the cellular properties of these neurons remain largely unknown. Here, we generated a knock-in mouse line in which CB1-expressing neurons expressed the fluorescent protein td-Tomato (tdT). Using these mice, we demonstrated that tdT-positive neurons within the NAc were exclusively fast-spiking interneurons (FSIs). These FSIs were electrically coupled with each other, and thus may help synchronize populations/ensembles of NAc neurons. CB1-expressing FSIs also form GABAergic synapses on adjacent medium spiny neurons (MSNs), providing feed-forward inhibition of NAc output. Furthermore, the membrane excitability of tdT-positive FSIs in the NAc was up-regulated after withdrawal from cocaine exposure, an effect that might increase FSI-to-MSN inhibition. Taken together with our previous findings that the membrane excitability of NAc MSNs is decreased during cocaine withdrawal, the present findings suggest that the basal functional output of the NAc is inhibited during cocaine withdrawal by multiple mechanisms. As such, CB1-expressing FSIs are targeted by cocaine exposure to influence the overall functional output of the NAc. PMID:23012412

  14. Sizing up the nucleus: nuclear shape, size and nuclear-envelope assembly

    PubMed Central

    Webster, Micah; Witkin, Keren L.; Cohen-Fix, Orna

    2009-01-01

    Summary The nucleus is one of the most prominent cellular organelles, yet surprisingly little is known about how it is formed, what determines its shape and what defines its size. As the nuclear envelope (NE) disassembles in each and every cell cycle in metazoans, the process of rebuilding the nucleus is crucial for proper development and cell proliferation. In this Commentary, we summarize what is known about the regulation of nuclear shape and size, and highlight recent findings that shed light on the process of building a nucleus, including new discoveries related to NE assembly and the relationship between the NE and the endoplasmic reticulum (ER). Throughout our discussion, we note interesting aspects of nuclear structure that have yet to be resolved. Finally, we present an idea – which we refer to as `the limited flat membrane hypothesis' – to explain the formation of a single nucleus that encompasses of all of the cell's chromosomes following mitosis. PMID:19420234

  15. Stimulation of the subthalamic nucleus improves velocity of ballistic movements in Parkinson's disease.

    PubMed

    Joundi, Raed A; Brittain, John-Stuart; Punt, T David; Green, Alex L; Jenkinson, Ned; Aziz, Tipu Z

    2012-04-18

    High-frequency stimulation of the subthalamic nucleus can markedly improve motor function in patients with Parkinson's disease. However, the underlying mechanisms mediating these improvements are not well understood. In particular, whether motor function is differentially improved in distal or proximal movements is not fully determined. Also, whether reaction time is improved along with other motor parameters is still a matter of debate. Here, we test patients OFF and ON subthalamic nucleus stimulation by capturing simple ballistic movements across four joints using kinematic motion analysis. We show that velocity, but not reaction time, is significantly improved with stimulation. There was no strong differential effect between joints. These results add evidence that deep brain stimulation of the subthalamic nucleus can enhance performance of ballistic movements in Parkinson's disease, and demonstrate that the subthalamic nucleus may be important in driving parameters of motor control after the response has been initiated.

  16. Producing a compound Nucleus via Inelastic Scattering: The 90Zr(alpha,alpha')90Zr* Case

    SciTech Connect

    Escher, J E; Dietrich, F S

    2008-05-23

    In a Surrogate reaction a compound nucleus is produced via a direct reaction (pickup, stripping, or inelastic scattering). For a proper application of the Surrogate approach it is necessary to predict the resulting angular momentum and parity distribution in the compound nucleus. A model for determining these distributions is developed for the case of inelastic alpha scattering off a spherical nucleus. The focus is on obtaining a first, simple description of the direct-reaction process that produces the compound nucleus and on providing the basis for a more complete treatment of the problem. The approximations employed in the present description are discussed and the extensions required for a more rigorous treatment of the problem are outlined. To illustrate the formalism, an application to {sup 90}Zr({alpha},{alpha}{prime}){sup 90}Zr* is presented.

  17. Robust Nucleus/Cell Detection and Segmentation in Digital Pathology and Microscopy Images: A Comprehensive Review.

    PubMed

    Xing, Fuyong; Yang, Lin

    2016-01-01

    Digital pathology and microscopy image analysis is widely used for comprehensive studies of cell morphology or tissue structure. Manual assessment is labor intensive and prone to interobserver variations. Computer-aided methods, which can significantly improve the objectivity and reproducibility, have attracted a great deal of interest in recent literature. Among the pipeline of building a computer-aided diagnosis system, nucleus or cell detection and segmentation play a very important role to describe the molecular morphological information. In the past few decades, many efforts have been devoted to automated nucleus/cell detection and segmentation. In this review, we provide a comprehensive summary of the recent state-of-the-art nucleus/cell segmentation approaches on different types of microscopy images including bright-field, phase-contrast, differential interference contrast, fluorescence, and electron microscopies. In addition, we discuss the challenges for the current methods and the potential future work of nucleus/cell detection and segmentation.

  18. Code System for Retrieving EXFOR Cross Section Data According to a Given Target Nucleus.

    1985-10-10

    Version 00 X4R retrieves EXFOR data according to a given target nucleus, reaction type, year range and incident energy range. These are then converted to a data table form which can easily be processed by computer.

  19. Internal dynamics of a living cell nucleus investigated by dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Suissa, M.; Place, C.; Goillot, E.; Freyssingeas, E.

    2008-08-01

    Recent progresses in cellular biology have shown that the nucleus of a living cell is a structured integration of many functional domains with a complex spatial organization. This organization, as well as molecular and biochemical processes, is time regulated. In the past years many investigations have been performed using fluorescent microscopy techniques to study the internal dynamics of the nucleus of a living cell. These investigations, however, have never focussed on the global internal dynamics of the nucleus, which is still unknown. In this article we present an original light scattering experimental device that we built to investigate this dynamics during biological processes. By means of this experimental set-up, we investigated the global dynamics of the nucleus of a living cell treated with a DNA replication inhibitor. This dynamics presents different and independent kinds of relaxation well separated in time that vary as a function of the cell cycle phases.

  20. Characterizing the nucleation flux of linked-flux model for core-shell composite nucleus

    NASA Astrophysics Data System (ADS)

    Iwamatsu, Masao

    2013-05-01

    The kinetics of nucleation of a core-shell composite nucleus that consists of a core of stable final phase surrounded by a wetting layer of an intermediate metastable phase is studied using the linked-flux model where the nucleation flux is considered in the two-dimensional space of stable and metastable components. The steady-state solution of the Fokker-Planck equation is considered not only in the size and composition space but also in the component space. It is shown that the kinetics of critical nucleus at the saddle point is more appropriately characterized in the size and composition space, while the kinetics of the post-critical nucleus is more appropriately described in the component space. Although both the free-energy landscape and the reaction rates play decisive role to determine the kinetics of nucleation at the saddle point, the details of the free energy landscape are irrelevant to the kinetics of the post critical nucleus.