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Sample records for proton-rich nucleus 24si

  1. Hindered proton collectivity in the proton-rich nucleus 28S: Possible magic number Z = 16

    NASA Astrophysics Data System (ADS)

    Togano, Y.; Yamada, Y.; Iwasa, N.; Yamada, K.; Motobayashi, T.; Aoi, N.; Baba, H.; Bishop, S.; Cai, X.; Doornenbal, P.; Fang, D.; Furukawa, T.; Ieki, K.; Kawabata, T.; Kanno, S.; Kobayashi, N.; Kondo, Y.; Kuboki, T.; Kume, N.; Kurita, K.; Kurokawa, M.; Ma, Y. G.; Matsuo, Y.; Murakami, H.; Matsushita, M.; Nakamura, T.; Okada, K.; Ota, S.; Satou, Y.; Shimoura, S.; Shioda, R.; Tanaka, K. N.; Takeuchi, S.; Tian, W.; Wang, H.; Wang, J.; Yoneda, K.

    2012-10-01

    The reduced transition probability B(E2;0gs+→21+) for the proton-rich nucleus 28S was determined experimentally using intermediate-energy Coulomb excitation. The resultant B(E2) value 181(31) e2fm4 is smaller than those of neighboring N = 12 isotones and Z = 16 isotopes. The double ratio |Mn/Mp|/(N/Z) of the 0gs+→21+ transition in 28S was obtained to be 1.9(2) by evaluating the Mn value from the known B(E2) value of the mirror nucleus 28Mg, showing the hindrance of proton collectivity relative to that of neutrons. These results indicate the emergence of the magic number Z = 16 in 28S.

  2. β -decay study of the Tz=-2 proton-rich nucleus 20Mg

    NASA Astrophysics Data System (ADS)

    Sun, L. J.; Xu, X. X.; Fang, D. Q.; Lin, C. J.; Wang, J. S.; Li, Z. H.; Wang, Y. T.; Li, J.; Yang, L.; Ma, N. R.; Wang, K.; Zang, H. L.; Wang, H. W.; Li, C.; Shi, C. Z.; Nie, M. W.; Li, X. F.; Li, H.; Ma, J. B.; Ma, P.; Jin, S. L.; Huang, M. R.; Bai, Z.; Wang, J. G.; Yang, F.; Jia, H. M.; Zhang, H. Q.; Liu, Z. H.; Bao, P. F.; Wang, D. X.; Yang, Y. Y.; Zhou, Y. J.; Ma, W. H.; Chen, J.; Ma, Y. G.; Zhang, Y. H.; Zhou, X. H.; Xu, H. S.; Xiao, G. Q.; Zhan, W. L.

    2017-01-01

    The β decay of the drip-line nucleus 20Mg gives important information on key astrophysical resonances in 20Na, which are relevant to the onset of the rapid proton capture process. A detailed β -decay spectroscopic study of 20Mg was performed by a continuous-implantation method. A detection system was specially developed for charged-particle decay studies, giving improved spectroscopic information including the delayed proton energies, the half-life of 20Mg, the excitation energies, the branching ratios, and the logf t values for the states in 20Na populated in the β decay of 20Mg. A new proton branch was observed and the corresponding excited state in 20Na was proposed. The large isospin asymmetry for the mirror decays of 20Mg and 20O was also well reproduced. To resolve the long-standing problem about the astrophysically interesting 2645 keV resonance in 20Na convincingly, a higher-statistics measurement may still be needed.

  3. Gamow-Teller strength distribution in proton-rich nucleus 57Zn and its implications in astrophysics

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un; Rahman, Muneeb-Ur

    2011-04-01

    Gamow-Teller (GT) transitions play a preeminent role in the collapse of stellar core in the stages leading to a Type-II supernova. The microscopically calculated GT strength distributions from ground and excited states are used for the calculation of weak decay rates for the core-collapse supernova dynamics and for probing the concomitant nucleosynthesis problem. The B(GT) strength for 57Zn is calculated in the domain of proton-neutron Quasiparticle Random Phase Approximation (pn-QRPA) theory. No experimental insertions were made (as usually made in other pn-QRPA calculations of B(GT) strength function) to check the performance of the model for proton-rich nuclei. The calculated B(GT) strength distribution is in good agreement with measurements and shows differences with the earlier reported shell model calculation. The pn-QRPA model reproduced the measured low-lying strength for 57Zn better in comparison to the KB3G interaction used in the large-scale shell model calculation. The stellar weak rates are sensitive to the location and structure of these low-lying states in daughter 57Cu. The structure of 57Cu plays a sumptuous role in the nucleosynthesis of proton-rich nuclei. The primary mechanism for producing such nuclei is the rp-process and is believed to be important in the dynamics of the collapsing supermassive stars. Small changes in the binding and excitation energies can lead to significant modifications of the predictions for the synthesis of proton rich isotopes. The β +-decay and electron capture (EC) rates on 57Zn are compared to the seminal work of Fuller, Fowler and Newman (FFN). The pn-QRPA calculated β +-decay rates are generally in good agreement with the FFN calculation. However at high stellar temperatures the calculated β +-decay rates are almost half of FFN rates. On the other hand, for rp-process conditions, the calculated electron capture ( β +-decay) rates are bigger than FFN rates by more than a factor 2 (1.5) and may have interesting

  4. 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.

  5. 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.

  6. Projected shell model study of odd-odd f-p-g shell proton-rich nuclei

    NASA Astrophysics Data System (ADS)

    Palit, R.; Sheikh, J. A.; Sun, Y.; Jain, H. C.

    2003-01-01

    A systematic study of two-quasiparticle bands of the proton-rich odd-odd nuclei in the mass A˜70 80 region is performed using the projected shell model approach. The study includes Br, Rb, and Y isotopes with N=Z+2 and Z+4. We describe the energy spectra and electromagnetic transition strengths in terms of the configuration mixing of the angular-momentum projected multi-quasiparticle states. Signature splitting and signature inversion in the rotational bands are discussed and are shown to be well described. A preliminary study of the odd-odd N=Z nucleus 74Rb, using the concept of spontaneous symmetry breaking is also presented.

  7. Beta-decay of proton-rich nucleus ^23Al and astrophysical consequences

    NASA Astrophysics Data System (ADS)

    Zhai, Y. J.; Iacob, V. E.; Al-Abdullah, T.; Fu, C.; Hardy, J. C.; Nica, N.; Park, H. I.; Tabacaru, G.; Trache, L.; Tribble, R. E.

    2006-04-01

    We will present the results of a β-decay study that was motivated by a nuclear astrophysics problem. For the first time γ-rays have been observed following the β decay of pure samples of ^23Al. We used the ^1H(^24Mg,2n)^23Al reaction and the MARS recoil separator of Texas A&M University. β and β-γ coincidence measurements were made with a fast tape-transport system and β and γ-ray detectors. The experiment allowed us to measure β branching ratios and deduce logft values for transitions to 14 final states in ^23Mg, including the isobaric analog state, and from them to determine unambigously the spin and parity of ^23Al ground state to be J^π=5/2^+. We will discuss how this excludes the large increase in the radiative proton-capture cross section for the reaction ^22Mg(p,γ)^23Al at astrophysical energies which was implied by claims that the spin and parity is J^π=1/2^+ [1,2], claims that motivated this study in the first place. The reaction is possible candidate to explain why space-based gamma-ray telescopes do not observe γ-rays from the decay of long-lived ^22Na formed in ONe novae explosions [3]: a larger cross section would be required to divert significant flux from the A=22 into the A=23 mass chain. [1] X. Z. Cai et al, Phys. Rev. C 65, 024610 (2002). [2] H.-Y. Zhang et al., Chin. Phys. Lett. 19, 1599 (2002). [3] M. Wiescher et al., Astrophys. J. 343, 352 (1989).

  8. {beta} decay of proton-rich nucleus {sup 23}Al and astrophysical consequences

    SciTech Connect

    Iacob, V. E.; Zhai, Y.; Al-Abdullah, T.; Fu, C.; Hardy, J. C.; Nica, N.; Park, H. I.; Tabacaru, G.; Trache, L.; Tribble, R. E.

    2006-10-15

    We present the first study of the {beta} decay of {sup 23}Al undertaken with pure samples. The study was motivated by nuclear astrophysics questions. Pure samples of {sup 23}Al were obtained from the momentum achromat recoil separator (MARS) of Texas A and M University, collected on a fast tape-transport system, and moved to a shielded location where {beta} and {beta}-{gamma} coincidence measurements were made. We deduced {beta} branching ratios and log ft values for transitions to states in {sup 23}Mg, and from them determined unambiguously the spin and parity of the {sup 23}Al ground state to be J{sup {pi}}=5/2{sup +}. We discuss how this excludes the large increases in the radiative proton capture cross section for the reaction {sup 22}Mg(p,{gamma}){sup 23}Al at astrophysical energies, which were implied by claims that the spin and parity is J{sup {pi}}=1/2{sup +}. The log ft for the Fermi transition to its isobaric analog state (IAS) in {sup 23}Mg is also determined for the first time. This IAS and a state 16 keV below it are observed, well separated in the same experiment for the first time. We can now solve a number of inconsistencies in the literature, exclude strong isospin mixing claimed before, and obtain a new determination of the resonance strength. Both states are resonances in the {sup 22}Na(p,{gamma}){sup 23}Mg reaction at energies important in novae. The reactions {sup 22}Mg(p,{gamma}){sup 23}Al and {sup 22}Na(p,{gamma}){sup 23}Mg have both been suggested as possible candidates for diverting some of the flux in oxygen-neon novae explosions from the A=22 into the A=23 mass 0011cha.

  9. Production of proton-rich nuclei around Z = 84-90 in fusion-evaporation reactions

    NASA Astrophysics Data System (ADS)

    Chen, Peng-Hui; Feng, Zhao-Qing; Niu, Fei; Guo, Ya-Fei; Zhang, Hong-Fei; Li, Jun-Qing; Jin, Gen-Ming

    2017-05-01

    Within the framework of the dinuclear system model, production cross sections of proton-rich nuclei with charged numbers of Z = 84-90 are investigated systematically. Possible combinations with the 28Si, 32S, 40Ar bombarding the target nuclides 165Ho, 169Tm, 170-174Yb, 175,176Lu, 174, 176-180Hf and 181Ta are analyzed thoroughly. The optimal excitation energies and evaporation channels are proposed to produce the proton-rich nuclei. The systems are feasible to be constructed in experiments. It is found that the neutron shell closure of N = 126 is of importance during the evaporation of neutrons. The experimental excitation functions in the 40Ar induced reactions can be nicely reproduced. The charged particle evaporation is comparable with neutrons in cooling the excited proton-rich nuclei, in particular for the channels with α and proton evaporation. The production cross section increases with the mass asymmetry of colliding systems because of the decrease of the inner fusion barrier. The channels with pure neutron evaporation depend on the isotopic targets. But it is different for the channels with charged particles and more sensitive to the odd-even effect.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Nucleosynthesis of proton-rich nuclei. Experimental results on the rp-process

    NASA Astrophysics Data System (ADS)

    Galaviz, D.; Amthor, A. M.; Bazin, D.; Becerril, A. D.; Brown, B. A.; Chen, A. A.; Cole, A.; Cook, J. M.; Elliot, T.; Estrade, A.; Fülöp, Z. S.; Gade, A.; Glasmacher, T.; Heger, A.; Howard, M. E.; Kessler, R.; Lorusso, G.; Matos, M.; Montes, F.; Müller, W.; Pereira, J.; Schatz, H.; Sherrill, B.; Schertz, F.; Shimbara, Y.; Smith, E.; Smith, K.; Tamii, A.; Stolz, A.; Weisshaar, D.; Wallace, M.; Wiescher, M.; Zegers, R. G. T.

    2010-01-01

    We report in this study the nuclear properties of proton-rich isotopes located along the rp-process path. The experiments have recently been performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The level properties above the proton separation energy of the nuclei 30S, 36K and 37Ca were measured with precision of < 10 keV. This will allow a reduction in the determination of the astrophysical (p,γ) reaction rate under rp-process conditions.

  15. 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)

  16. 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.}

  17. 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}

  18. 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.

  19. Direct mass measurements of proton-rich nuclei in the region from tellurium to polonium

    NASA Astrophysics Data System (ADS)

    Wollnik, H.; Beckert, K.; Beha, T.; Bosch, F.; Eickhoff, H.; Franzke, B.; Fujita, Y.; Geissel, H.; Haussmann, M.; Irnich, H.; Jung, H. C.; Kerscher, Th.; Klepper, O.; Kluge, H.-J.; Kozhuharov, C.; Kraus, G.; Löbner, K. E. G.; Münzenberg, G.; Nickel, F.; Nolden, F.; Novikov, Yu.; Radon, T.; Reich, H.; Scheidenberger, C.; Schlitt, B.; Schwab, W.; Schwinn, A.; Steck, M.; Sümmerer, K.

    1997-02-01

    In recent experiments using the FRS-ESR facilities at GSI we have measured the masses of 225 proton-rich nuclei in the range of 135≤A≤209. Applying the new technique of Schottky-Mass Spectrometry an accuracy of about 100 keV and a resolving power of 4 · 10 5 was achieved. Masses for cooled projectile fragments with half-lives larger than a few seconds were determined by their revolution frequencies in the ESR. Reliable predictions for the proton-drip line can be made for elements from bismuth to protactinium using the precisely measured Qα-values from literature and our new mass values for the isotopes at the ends of the corresponding α-chains.

  20. The decay of proton-rich nuclei in the mass A=36 56 region

    NASA Astrophysics Data System (ADS)

    Dossat, C.; Adimi, N.; Aksouh, F.; Becker, F.; Bey, A.; Blank, B.; Borcea, C.; Borcea, R.; Boston, A.; Caamano, M.; Canchel, G.; Chartier, M.; Cortina, D.; Czajkowski, S.; de France, G.; de Oliveira Santos, F.; Fleury, A.; Georgiev, G.; Giovinazzo, J.; Grévy, S.; Grzywacz, R.; Hellström, M.; Honma, M.; Janas, Z.; Karamanis, D.; Kurcewicz, J.; Lewitowicz, M.; López Jiménez, M. J.; Mazzocchi, C.; Matea, I.; Maslov, V.; Mayet, P.; Moore, C.; Pfützner, M.; Pravikoff, M. S.; Stanoiu, M.; Stefan, I.; Thomas, J. C.

    2007-08-01

    In a series of experiments at the SISSI/LISE3 facility of GANIL conducted between 1999 and 2004, we have collected decay information for proton-rich nuclei between 36Ca and 56Zn. The data allowed us to study the decay properties of 26 nuclei. The main experimental information obtained for all nuclei is their β-decay half-life and their total β-delayed proton emission branching ratio. For many nuclei, individual proton groups and γ rays were identified and allowed us to establish first partial decay schemes for some of the nuclei studied. In addition, mass-excess values have been determined for some of the nuclei by means of the isobaric multiplet mass equation. For 50Ni, the decay via β-delayed two-proton emission could be tentatively identified. The decay of 49Ni allowed for the first time to identify the first 2 state in 48Fe. The experimental data are confronted to model predictions for the half-life and the mass-excess values.

  1. Examination of experimental conditions for the production of proton-rich and neutron-rich hypernuclei

    NASA Astrophysics Data System (ADS)

    Rappold, C.; López-Fidalgo, J.

    2016-10-01

    After the demonstration of the feasibility of hypernuclear spectroscopy with heavy-ion beams, the HypHI Collaboration will next focus on the study of proton- and neutron-rich hypernuclei. The use of a fragment separator for the production and separation of rare-isotope beams is a crucial aspect to producing hypernuclei far from the stability line. Precise spectroscopy of exotic hypernuclei is planned to be carried out at the GSI and later at the FAIR facility with the FRS and Super-FRS fragment separators. A systematic study and an optimization analysis were performed to determine optimal experimental conditions for producing hypernuclei with high isospin. The optimal conditions are obtained based on theoretical models for the heavy-ion induced reaction and hypernuclei production. Experimental efficiencies for the production of exotic secondary beams were also taken into account via Monte Carlo simulations of the fragment separator. The developed methodology is presented to deduce the expected yields of Be8Λ and subsequently other proton-rich and neutron-rich hypernuclei.

  2. The decay of proton-rich nuclei in the mass A = 36 56 region

    SciTech Connect

    Dossat, C.; Aksouh, F.; Becker, F.; Bey, A.; Borcea, C.; Borcea, R.; Boston, A.; Caamano, M.; Canchel, G.; Czajkowski, S.; de Oliveira Santos, F.; Fleury, A.; Giovinazzo, J.; Grzywacz, Robert Kazimierz; Hellstrom, M.; Honma, M.; Janas, Z.; Karamanis, D.; Lewitowicz, M.; Lopez Jimenez, M. J.; Matea, I.; Maslov, V.; Mayet, P.; Moore, C.; Pfutzner, M.; Pravikoff, M. S.; Stefan, I.; Thomas, J.-C.

    2007-01-01

    In a series of experiments at the SISSI/LISE3 facility of GANIL conducted between 1999 and 2004, we have collected decay information for proton-rich nuclei between {sup 36}Ca and {sup 56}Zn. The data allowed us to study the decay properties of 26 nuclei. The main experimental information obtained for all nuclei is their {beta}-decay half-life and their total {beta}-delayed proton emission branching ratio. For many nuclei, individual proton groups and {gamma} rays were identified and allowed us to establish first partial decay schemes for some of the nuclei studied. In addition, mass-excess values have been determined for some of the nuclei by means of the isobaric multiplet mass equation. For {sup 50}Ni, the decay via {beta}-delayed two-proton emission could be tentatively identified. The decay of {sup 49}Ni allowed for the first time to identify the first 2{sup +} state in {sup 48}Fe. The experimental data are confronted to model predictions for the half-life and the mass-excess values.

  3. Particle-number projected electric quadrupole moment of even-even proton-rich nuclei in the isovector pairing case

    NASA Astrophysics Data System (ADS)

    Douici, Mohamed; Allal, Nassima-Hosni; Fellah, Mohamed; Benhamouda, Naziha; Oudih, Mohamed-Reda

    2014-03-01

    The effect of the particle-number projection on the electric quadrupole moment (Q2) of even-even proton-rich nuclei is studied in the isovector neutron-proton (np) pairing case. As a first step, an expression of the electric quadrupole moment, which takes into account the isovector np pairing effect and which conserves the particle-number, is established within the Sharp-BCS (SBCS) method. This expression does generalize the one used in the pairing between like-particles case. As a second step, Q2 is calculated for even-even proton-rich nuclei using the single-particle energies of a Woods-Saxon mean-field. The obtained results are compared with the results obtained in the pairing between like-particles case. It is shown that the np pairing effect, as well as the projection one, is maximal when N=Z.

  4. Structure of high spin state in proton-rich 74,76,78Kr isotopes: A projected shell model description

    NASA Astrophysics Data System (ADS)

    Liu, YanXin; Yu, ShaoYing; Shen, CaiWan

    2015-01-01

    The N≈ Z nuclei in the mass A˜80 region has been researched because of an abundance of nuclear structure phenomena. The projected shell model (PSM) was adopted to investigate the structure of high spin state in proton-rich 74,76,78Kr isotopes including yrast spectra, moment of inertia, electric quadrupole transitions and the behavior of single particle. The calculated results are in good agreement with available data and the shape coexistence in low-spin is also discussed.

  5. Shape coexistence effects on stellar weak interaction rates of proton-rich nuclei within beyond-mean-field approach

    NASA Astrophysics Data System (ADS)

    Petrovici, A.; Andrei, O.

    2017-06-01

    Relevant for the astrophysical rp-process, proton-rich A˜70 nuclei manifesting shape coexistence have been investigated in the frame of the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using the effective interaction obtained from a G-matrix based on BonnA/BonnCD potential. Reliable predictions on stellar weak interaction rates emerged starting from the realistic description of the experimentally accesible properties. The influence of shape coexistence and mixing in the structure of the low-lying parent states as well as in the independently calculated daughter states on weak interaction rates under X-ray burst environment is discussed.

  6. 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.

  7. 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.

  8. Different mechanism of two-proton emission from proton-rich nuclei 23Al and 22Mg

    NASA Astrophysics Data System (ADS)

    Ma, Y. G.; Fang, D. Q.; Sun, X. Y.; Zhou, P.; Togano, Y.; Aoi, N.; Baba, H.; Cai, X. Z.; Cao, X. G.; Chen, J. G.; Fu, Y.; Guo, W.; Hara, Y.; Honda, T.; Hu, Z. G.; Ieki, K.; Ishibashi, Y.; Ito, Y.; Iwasa, N.; Kanno, S.; Kawabata, T.; Kimura, H.; Kondo, Y.; Kurita, K.; Kurokawa, M.; Moriguchi, T.; Murakami, H.; Ooishi, H.; Okada, K.; Ota, S.; Ozawa, A.; Sakurai, H.; Shimoura, S.; Shioda, R.; Takeshita, E.; Takeuchi, S.; Tian, W. D.; Wang, H. W.; Wang, J. S.; Wang, M.; Yamada, K.; Yamada, Y.; Yasuda, Y.; Yoneda, K.; Zhang, G. Q.; Motobayashi, T.

    2015-04-01

    Two-proton relative momentum (qpp) and opening angle (θpp) distributions from the three-body decay of two excited proton-rich nuclei, namely 23Al → p + p +21Na and 22Mg → p + p +20Ne, have been measured with the projectile fragment separator (RIPS) at the RIKEN RI Beam Factory. An evident peak at qpp ∼ 20 MeV / c as well as a peak in θpp around 30° are seen in the two-proton break-up channel from a highly-excited 22Mg. In contrast, such peaks are absent for the 23Al case. It is concluded that the two-proton emission mechanism of excited 22Mg is quite different from the 23Al case, with the former having a favorable diproton emission component at a highly excited state and the latter dominated by the sequential decay process.

  9. High-precision β decay half-life measurements of proton-rich nuclei for testing the CVC hypothesis

    NASA Astrophysics Data System (ADS)

    Kurtukian-Nieto, T.

    2011-11-01

    The experimental study of super-allowed nuclear β decays serves as a sensitive probe of the conservation of the weak vector current (CVC) and allows tight limits to be set on the presence of scalar or right-handed currents. Once CVC is verified, it is possible to determine the Vud element of the CKM quark-mixing matrix. Similarly, the study of nuclear mirror β decays allows to arrive at the same final quantity Vud. Whereas dedicated studies of 0+ → 0+ decays are performed for several decades now, the potential of mirror transitions was only rediscovered recently. Therefore, it can be expected that important progress is possible with high-precision studies of different mirror β decays. In the present piece of work the half-life measurements performed by the CENBG group of the proton-rich nuclei 42Ti, 38-39Ca, 30-31S and 29P are summarised.

  10. 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.}

  11. High-precision {beta} decay half-life measurements of proton-rich nuclei for testing the CVC hypothesis

    SciTech Connect

    Kurtukian-Nieto, T. [Centre d'Etudes Nucleaires de Bordeaux-Gradignan , Universite Bordeaux 1, CNRS Collaboration: NEX Group of CENBG

    2011-11-30

    The experimental study of super-allowed nuclear {beta} decays serves as a sensitive probe of the conservation of the weak vector current (CVC) and allows tight limits to be set on the presence of scalar or right-handed currents. Once CVC is verified, it is possible to determine the V{sub ud} element of the CKM quark-mixing matrix. Similarly, the study of nuclear mirror {beta} decays allows to arrive at the same final quantity V{sub ud}. Whereas dedicated studies of 0{sup +}{yields}0{sup +} decays are performed for several decades now, the potential of mirror transitions was only rediscovered recently. Therefore, it can be expected that important progress is possible with high-precision studies of different mirror {beta} decays. In the present piece of work the half-life measurements performed by the CENBG group of the proton-rich nuclei {sup 42}Ti, {sup 38-39}Ca, {sup 30-31}S and {sup 29}P are summarised.

  12. 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.

  13. Large exchange-bias in Ni55Mn19Al24Si2 polycrystalline ribbons

    NASA Astrophysics Data System (ADS)

    Singh, Rohit; Ingale, Babita; Varga, Lajos K.; Khovaylo, Vladimir V.; Chatterjee, Ratnamala

    2014-09-01

    The crystal structure, phase transition and exchange bias effect in induction melted polycrystalline ribbons of Ni55Mn19Al24Si2 have been studied using room temperature x-ray diffraction (XRD), differential scanning calorimetry (DSC) and magnetic measurements. The sample was found to show structural transformation temperatures such as austenite start (As)=306 K, austenite finish (Af)=316 K, martensite start (Ms)=305 K and martensite finish (Mf)=294 K all above room temperature. The room temperature structure evaluated as orthorhombic 14 M with lattice parameters a=4.14 Å, b=29.84 Å, and c=5.72 Å. Importantly at 2 K, the sample showed a large exchange bias field of about 2520 Oe, which is the maximum value ever reported among the Heusler alloy samples.

  14. 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.

  15. Precursor routes to quaternary intermetallics: Synthesis, crystal structure, and physical properties of clathrate-II Cs8Na16Al24Si112

    NASA Astrophysics Data System (ADS)

    Wei, Kaya; Dong, Yongkwan; Nolas, George S.

    2016-05-01

    A new quaternary clathrate-II composition, Cs8Na16Al24Si112, was synthesized by kinetically controlled thermal decomposition (KCTD) employing both NaSi and NaAlSi as the precursors and CsCl as a reactive flux. The crystal structure and composition of Cs8Na16Al24Si112 were investigated using both Rietveld refinement and elemental analysis, and the temperature dependent transport properties were investigated. Our results indicate that KCTD with multiple precursors is an effective method for the synthesis of multinary inorganic phases that are not easily accessible by traditional solid-state synthesis or crystal growth techniques.

  16. High energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Wosiek, B.

    1986-01-01

    Experimental results on high energy nucleus-nucleus interactions are presented. The data are discussed within the framework of standard super-position models and from the point-of-view of the possible formation of new states of matter in heavy ion collisions.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Precursor routes to quaternary intermetallics: Synthesis, crystal structure, and physical properties of clathrate-II Cs{sub 8}Na{sub 16}Al{sub 24}Si{sub 112}

    SciTech Connect

    Wei, Kaya; Dong, Yongkwan; Nolas, George S.

    2016-05-15

    A new quaternary clathrate–II composition, Cs{sub 8}Na{sub 16}Al{sub 24}Si{sub 112}, was synthesized by kinetically controlled thermal decomposition (KCTD) employing both NaSi and NaAlSi as the precursors and CsCl as a reactive flux. The crystal structure and composition of Cs{sub 8}Na{sub 16}Al{sub 24}Si{sub 112} were investigated using both Rietveld refinement and elemental analysis, and the temperature dependent transport properties were investigated. Our results indicate that KCTD with multiple precursors is an effective method for the synthesis of multinary inorganic phases that are not easily accessible by traditional solid-state synthesis or crystal growth techniques. - Graphical abstract: Quaternary Cs{sub 8}Na{sub 16}Al{sub 24}S{sub 112} clathrate–II was synthesized for the first time by kinetically controlled thermal decomposition (KCTD) employing a NaSi+NaAlSi precursor mixture with CsCl as the reactive flux, and the structural and transport properties were investigated. Our approach demonstrates a new synthetic pathway for the synthesis of multinary inorganic compounds. This work reports the exploration of a new clathrate composition as this class of materials continues to be of interest for thermoelectrics and other energy-related applications.

  5. Leukocyte nucleus segmentation and nucleus lobe counting.

    PubMed

    Chan, Yung-Kuan; Tsai, Meng-Hsiun; Huang, Der-Chen; Zheng, Zong-Han; Hung, Kun-Ding

    2010-11-12

    Leukocytes play an important role in the human immune system. The family of leukocytes is comprised of lymphocytes, monocytes, eosinophils, basophils, and neutrophils. Any infection or acute stress may increase or decrease the number of leukocytes. An increased percentage of neutrophils may be caused by an acute infection, while an increased percentage of lymphocytes can be caused by a chronic bacterial infection. It is important to realize an abnormal variation in the leukocytes. The five types of leukocytes can be distinguished by their cytoplasmic granules, staining properties of the granules, size of cell, the proportion of the nuclear to the cytoplasmic material, and the type of nucleolar lobes. The number of lobes increased when leukemia, chronic nephritis, liver disease, cancer, sepsis, and vitamin B12 or folate deficiency occurred. Clinical neutrophil hypersegmentation has been widely used as an indicator of B12 or folate deficiency.Biomedical technologists can currently recognize abnormal leukocytes using human eyes. However, the quality and efficiency of diagnosis may be compromised due to the limitations of the biomedical technologists' eyesight, strength, and medical knowledge. Therefore, the development of an automatic leukocyte recognition system is feasible and necessary. It is essential to extract the leukocyte region from a blood smear image in order to develop an automatic leukocyte recognition system. The number of lobes increased when leukemia, chronic nephritis, liver disease, cancer, sepsis, and vitamin B12 or folate deficiency occurred. Clinical neutrophil hypersegmentation has been widely used as an indicator of B12 or folate deficiency. The purpose of this paper is to contribute an automatic leukocyte nuclei image segmentation method for such recognition technology. The other goal of this paper is to develop the method of counting the number of lobes in a cell nucleus. The experimental results demonstrated impressive segmentation accuracy

  6. 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.

  7. Reality of comet nucleus.

    NASA Technical Reports Server (NTRS)

    Lyttleton, R. A.

    1972-01-01

    The prime problem of a comet mission must be to settle whether the cometary nucleus has an actual tangible material existence, or whether it arises from some optical effect present only at times within comets. The absence of any large particles in a comet seems to be demonstrated by certain meteor showers. A feature that would seem to indicate that a comet consists primarily of a swarm of particles is that the coma in general contracts as the comet approaches the sun, roughly in proportion within the distance, and then expands again as it recedes.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Networking the nucleus

    PubMed Central

    Rajapakse, Indika; Scalzo, David; Tapscott, Stephen J; Kosak, Steven T; Groudine, Mark

    2010-01-01

    The nuclei of differentiating cells exhibit several fundamental principles of self-organization. They are composed of many dynamical units connected physically and functionally to each other—a complex network—and the different parts of the system are mutually adapted and produce a characteristic end state. A unique cell-specific signature emerges over time from complex interactions among constituent elements that delineate coordinate gene expression and chromosome topology. Each element itself consists of many interacting components, all dynamical in nature. Self-organizing systems can be simplified while retaining complex information using approaches that examine the relationship between elements, such as spatial relationships and transcriptional information. These relationships can be represented using well-defined networks. We hypothesize that during the process of differentiation, networks within the cell nucleus rewire according to simple rules, from which a higher level of order emerges. Studying the interaction within and among networks provides a useful framework for investigating the complex organization and dynamic function of the nucleus. PMID:20664641

  14. 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.

  15. Momentum loss in proton-nucleus and nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Khan, Ferdous; Townsend, Lawrence W.

    1993-01-01

    An optical model description, based on multiple scattering theory, of longitudinal momentum loss in proton-nucleus and nucleus-nucleus collisions is presented. The crucial role of the imaginary component of the nucleon-nucleon transition matrix in accounting for longitudinal momentum transfer is demonstrated. Results obtained with this model are compared with Intranuclear Cascade (INC) calculations, as well as with predictions from Vlasov-Uehling-Uhlenbeck (VUU) and quantum molecular dynamics (QMD) simulations. Comparisons are also made with experimental data where available. These indicate that the present model is adequate to account for longitudinal momentum transfer in both proton-nucleus and nucleus-nucleus collisions over a wide range of energies.

  16. The Galactic Nucleus

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio

    Exciting new broadband observations of the galactic nucleus have placed the heart of the Milky Way under intense scrutiny in recent years. This has been due in part to the growing interest from theorists motivated to study the physics of black hole accretion, magnetized gas dynamics, and unusual star formation. The center of our Galaxy is now known to harbor the most compelling supermassive black hole candidate, weighing in at 3-4 million solar masses. Its nearby environment is comprised of a molecular dusty ring, clusters of evolved and young stars, diffuse hot gas, ionized gas streamers, and several supernova remnants. This chapter will focus on the physical makeup of this dynamic region and the feasibility of actually imaging the black hole's shadow in the coming decade with mm interferometry.

  17. The intercalatus nucleus of Staderini.

    PubMed

    Cascella, Marco

    2016-01-01

    Rutilio Staderini was one of the leading Italian anatomists of the twentieth century, together with some scientists, such as Giulio Chiarugi, Giovanni Vitali, and others. He was also a member of a new generation of anatomists. They had continued the tradition of the most famous Italian scientists, which started from the Renaissance up until the nineteenth century. Although he carried out important studies of neuroanatomy and comparative anatomy, as well as embryology, his name is rarely remembered by most medical historians. His name is linked to the nucleus he discovered: the Staderini nucleus or intercalated nucleus, a collection of nerve cells in the medulla oblongata located lateral to the hypoglossal nucleus. This article focuses on the biography of the neuroanatomist as well as the nucleus that carries his name and his other research, especially on comparative anatomy and embryology.

  18. Mechanics of the Nucleus

    PubMed Central

    Lammerding, Jan

    2015-01-01

    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. PMID:23737203

  19. 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

  20. 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.

  1. Surface albedo of cometary nucleus

    NASA Astrophysics Data System (ADS)

    Mukai, T.; Mukai, S.

    A variation of the albedo on the illuminated disk of a comet nucleus is estimated, taking into account the multiple reflection of incident light due to small scale roughness. The dependences of the average albedo over the illuminated disk on the degree of roughness and on the complex refractive index of the surface materials are examined. The variation estimates are compared with measurements of the nucleus albedo of Comet Halley (Reitsema et al., 1987).

  2. 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.

  3. 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.

  4. 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.

  5. Proton-Rich Sulphur and Nucleosynthesis in Classical Novae

    SciTech Connect

    Chen, A. A.; Setoodehnia, K.; Chen, J.; Geraedts, S. D.; Clark, J. A.; Deibel, C. M.; Kahl, D.; Parker, P. D.; Seiler, D.; Wrede, C.

    2011-11-30

    The structure of proton-unbound states in {sup 30}{sub S} and {sup 31}{sub S} is important for determining the {sup 29}P(p,{gamma}){sup 30}S and {sup 30}P(p,{gamma}){sup 31}S reaction rates, which influence explosive hydrogen burning in classical novae. The former reaction rate in this temperature regime had been previously predicted to be dominated by two low-lying, unobserved, J{sup {pi}} = 3{sup +} and 2{sup +} resonances in {sup 30}S. To search for evidence for these levels, the structure of {sup 30}{sub S} was studied using the {sup 32}S(p,t){sup 30}S reaction with a magnetic spectrograph. We provide an update on the status of the ongoing analysis and some preliminary results.

  6. Low energy antiproton nucleus interactions

    SciTech Connect

    Sainio, M.E.; Ashford, V.; Sakitt, M.; Skelly, J.; Debbe, R.; Fickinger, W.; Marino, R.; Robinson, D.K.

    1984-05-01

    We have studied antiproton quasielastic scattering on Al, Cu, and Pb for two incident momenta, 514 and 633 MeV/c. Combining these data with other existing anti p nucleus data, we have performed a global analysis using a nonrelativistic optical potential of the Woods-Saxon form.

  7. Comet Odyssey: Comet Nucleus Orbiter

    NASA Astrophysics Data System (ADS)

    Weissman, P. R.; Smythe, W. D.; Spitz, S. J.; Bernard, D. E.; Bailey, R. W.

    2004-11-01

    Comet Odyssey is a comet nucleus orbiter mission, proposed to NASA's Discovery program in 2004. The goal of the mission is to completely characterize a cometary nucleus, both physically and compositionally, as can only be done during an extended rendezvous and not with a fast flyby. Comet Odyssey will launch in October 2009 on a Delta II 7925 and use a solar-electric powered spacecraft to effect a rendezvous with periodic comet 46P/Wirtanen in October 2013. Arrival is 96 days after perihelion at a heliocentric distance of 1.61 AU. Comet Odyssey's science payload includes narrow- and wide-angle CCD cameras, an infrared thermal imager, a gas chromatograph/mass spectrometer, an XRD/XRF dust compositional analyzer, and a dust counter and accumulation sensors. The Comet Odyssey spacecraft implementation uses a high heritage approach of flight proven and redundant hardware. The 3-engine ion propulsion subsystem is derived from that on Dawn but includes the capability for multi-engine thrusting. Comet Odyssey will approach the Wirtanen nucleus and make repeated slow flybys through the active cometary coma for a period of three months. It will then be placed in a ˜100-km radius orbit around the nucleus, with a plan to eventually orbit at 40-km altitude or less. From that altitude the narrow-angle camera will map the entire nucleus surface at 1 meter/pixel and the thermal imager will map at 19 meter/pixel. The orbital portion of the nominal mission will last 4.5 months, following the comet outward from the Sun to 3.3 AU as the comet evolves from an active to a quiescent state. En route to P/Wirtanen, the Comet Odyssey spacecraft will perform a close flyby of the 200-km diameter, G-type, main belt asteroid 19 Fortuna in January 2012 and make appropriate remote sensing observations.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  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. 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.

  14. Checkerboard Theory of the Nucleus.

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2006-04-01

    The Checker Board Model (CBM) is a 2D model of the nucleus that proposes that the synchronization of the 2 outer rotating quarks in the nucleons accounts for magnetic moment of the nucleons and that the magnetic flux from the nucleons couples (weaves) into the 2D checker board array structures and this magnetic coupling in addition to electrostatic forces of the rotating and stationary quarks accounts for the apparent strong nuclear force. The symmetry of the He nucleus helps explain why this 2D structure is so stable. This model explain the mass of the proton and neutron, along with their magnetic moments and their absolute and relative sizes in terms of the above structure and predict the masses of two newly proposed quarks ^(1): the ``up'' and the ``dn'' quarks. Since the masses of the ``up'' and ``dn'' quark determined by the CBM (237.31 MeV and 42.392 MeV respectively) did not fit within the standard model as candidates for u and d, a new model (New Physics) had to be invented. This new particle physics model predicts that nature has 5 generations not 3. (1). T.M. Lach, Checkerboard Structure of the Nucleus, Infinite Energy, Vol. 5, issue 30, (2000). (2). T.M. Lach, Masses of the Sub-Nuclear Particles, nucl-th/0008026, @http://xxx.lanl.gov/

  15. Targeted delivery to the nucleus.

    PubMed

    Pouton, Colin W; Wagstaff, Kylie M; Roth, Daniela M; Moseley, Gregory W; Jans, David A

    2007-08-10

    Macromolecules and supramolecular complexes are frequently required to enter and exit the nucleus during normal cell function, but access is restricted and exchange to and from the nucleus is tightly controlled. We describe the mechanisms which regulate nuclear import of endogenous molecules and indicate how viruses exploit these mechanisms during their life cycle. Opportunities exist to make use of natural pathways for delivery of therapeutic entities, in particular to develop safe and effective methods for gene therapy, although past attempts to design non-viral nuclear delivery systems have met with limited success. To increase the likelihood of success scientists will need an appreciation of the mechanisms by which viruses deliver their genomes to the nucleus, and will need a commitment to control the architecture of non-viral delivery systems at the molecular level. Effective delivery systems will require several attributes to facilitate endosomal escape, microtubular transport and uptake through the nuclear pore complex. The published literature provides a strong foundation for design of nuclear targeting systems. The challenge faced by delivery scientists is to assemble a system which is as effective as, for example, the adenovirus but which lacks its immunogenicity. This article reviews the relevant literature and indicates key areas for future research.

  16. 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.

  17. Classifiers for centrality determination in proton-nucleus and nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Altsybeev, Igor; Kovalenko, Vladimir

    2017-03-01

    Centrality, as a geometrical property of the collision, is crucial for the physical interpretation of nucleus-nucleus and proton-nucleus experimental data. However, it cannot be directly accessed in event-by-event data analysis. Common methods for centrality estimation in A-A and p-A collisions usually rely on a single detector (either on the signal in zero-degree calorimeters or on the multiplicity in some semi-central rapidity range). In the present work, we made an attempt to develop an approach for centrality determination that is based on machine-learning techniques and utilizes information from several detector subsystems simultaneously. Different event classifiers are suggested and evaluated for their selectivity power in terms of the number of nucleons-participants and the impact parameter of the collision. Finer centrality resolution may allow to reduce impact from so-called volume fluctuations on physical observables being studied in heavy-ion experiments like ALICE at the LHC and fixed target experiment NA61/SHINE on SPS.

  18. 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.

  19. Absence of jet quenching in peripheral nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Loizides, Constantin; Morsch, Andreas

    2017-10-01

    Medium effects on the production of high-pT particles in nucleus-nucleus (AA) collisions are generally quantified by the nuclear modification factor (RAA), defined to be unity in absence of nuclear effects. Modeling particle production including a nucleon-nucleon impact parameter dependence, we demonstrate that RAA at midrapidity in peripheral AA collisions can be significantly affected by event selection and geometry biases. Even without jet quenching and shadowing, these biases cause an apparent suppression for RAA in peripheral collisions, and are relevant for all types of hard probes and all collision energies. Our studies indicate that calculations of jet quenching in peripheral AA collisions should account for the biases, or else they will overestimate the relevance of parton energy loss. Similarly, expectations of parton energy loss in light-heavy collision systems based on comparison with apparent suppression seen in peripheral RAA should be revised. Our interpretation of the peripheral RAA data would unify observations for lighter collision systems or lower energies where significant values of elliptic flow are observed despite the absence of strong jet quenching.

  20. Nucleus morphology of Comet Halley

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Images obtained by the Halley multicolor camera were used to determine the projected size and shape of the nucleus. The location of the terminator and numerous surface features were determined. There is good correlation between the brightest surface features and the dust jets; however, many bright features are seen which are not associated with jets. Most of the observed features are circular and appear to be related to surface elevation. The angularity of the terminator gives an indication of the three-dimensional structure of the face which was observed.

  1. Exceptionally bright, compact starburst nucleus

    SciTech Connect

    Margon, B.; Anderson, S.F.; Mateo, M.; Fich, M.; Massey, P.

    1988-11-01

    Observations are reported of a remarkably bright (V about 13) starburst nucleus, 0833 + 652, which has been detected at radio, infrared, optical, ultraviolet, and X-ray wavelengths. Despite an observed flux at each of these wavelengths which is comparable to that of NGC 7714, often considered the 'prototypical' example of the starburst phenomenon, 0833 + 652 appears to be a previously uncataloged object. Its ease of detectability throughout the electromagnetic spectrum should make it useful for a variety of problems in the study of compact emission-line galaxies. 30 references.

  2. How viruses access the nucleus.

    PubMed

    Cohen, Sarah; Au, Shelly; Panté, Nelly

    2011-09-01

    Many viruses depend on nuclear proteins for replication. Therefore, their viral genome must enter the nucleus of the host cell. In this review we briefly summarize the principles of nucleocytoplasmic transport, and then describe the diverse strategies used by viruses to deliver their genomes into the host nucleus. Some of the emerging mechanisms include: (1) nuclear entry during mitosis, when the nuclear envelope is disassembled, (2) viral genome release in the cytoplasm followed by entry of the genome through the nuclear pore complex (NPC), (3) capsid docking at the cytoplasmic side of the NPC, followed by genome release, (4) nuclear entry of intact capsids through the NPC, followed by genome release, and (5) nuclear entry via virus-induced disruption of the nuclear envelope. Which mechanism a particular virus uses depends on the size and structure of the virus, as well as the cellular cues used by the virus to trigger capsid disassembly and genome release. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import. 2010 Elsevier B.V. All rights reserved.

  3. 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.

  4. 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.

  5. Oocyte nucleus controls progression through meiotic maturation.

    PubMed

    Polanski, Zbigniew; Hoffmann, Steffen; Tsurumi, Chizuko

    2005-05-15

    We analyzed progression through the meiotic maturation in oocytes manipulated to replace the prophase oocyte nucleus with the nucleus from a cumulus cell, a pachytene spermatocyte or the pronucleus from a fertilized egg. Removal of the oocyte nucleus led to a significant reduction in histone H1 kinase activity. Replacement of the oocyte nucleus by a pronucleus followed by culture resulted in premature pseudomeiotic division and occasional abnormal cytokinesis; however, histone H1 kinase activity was rescued, microtubules formed a bipolar spindle, and chromosomes were condensed. In addition to the anomalies observed after pronuclear transfer, those after transfer of the nucleus from a cumulus cell or spermatocyte included a dramatically impaired ability to form the bipolar spindle or to condense chromosomes, and histone H1 kinase activity was not rescued. Expression of a cyclin B-YFP in enucleated oocytes receiving the cumulus cell nucleus rescued histone H1 kinase activity, but spindle formation and chromosome condensation remained impaired, indicating a pleiotropic effect of oocyte nucleus removal. However, when the cumulus cell nucleus was first transformed into pronuclei (transfer into a metaphase II oocyte followed by activation), such pronuclei supported maturation after transfer into the oocyte in a manner similar to that of normal pronuclei. These results show that the oocyte nucleus contains specific components required for the control of progression through the meiotic maturation and that some of these components are also present in pronuclei.

  6. Projections from the cochlear nucleus to the superior paraolivary nucleus in guinea pigs.

    PubMed

    Schofield, B R

    1995-09-11

    Axonal tracing techniques were used to study the projection from the cochlear nucleus to the superior paraolivary nucleus in guinea pigs. Different tracers were used to identify the cell types that give rise to the projections, the morphology of their axons, and the cell types that they contact in the superior paraolivary nucleus. Injections of Fluoro-Gold or peroxidase-labeled-WGA and HRP into the superior paraolivary nucleus labeled multipolar cells and octopus cells bilaterally in the ventral cochlear nucleus, mainly on the contralateral side. Injections of PHAL into the ventral cochlear nucleus labeled two types of axons in the superior paraolivary nucleus. Thin axons branch infrequently and give rise primarily to small, en passant boutons. Thick axons have larger boutons, many of which are terminal boutons that arise from short collaterals. Thin axons appear to originate from multipolar cells, whereas thick axons probably originate from octopus cells. Both types are found bilaterally after an injection into the ventral cochlear nucleus on one side. Individual thick or thin axons may contact multiple cell types in the superior paraolivary nucleus. Individual cells in the superior paraolivary nucleus can receive convergent input from both thick and thin axons. Combined anterograde and retrograde transport of different fluorescent tracers was used to identify the projections of the cells in the superior paraolivary nucleus that receive inputs from the ventral cochlear nucleus. Cells in the superior paraolivary nucleus that projected to the ipsilateral cochlear nucleus or to the ipsilateral inferior colliculus appeared to be contacted by axons that were labeled by anterograde transport from the contralateral ventral cochlear nucleus. Thus the projections to the superior paraolivary nucleus are in a position to affect the activity in both ascending and descending auditory pathways.

  7. Projections from the central amygdaloid nucleus to the precuneiform nucleus in the mouse.

    PubMed

    Liang, Huazheng; Watson, Charles; Paxinos, George

    2015-01-01

    The mouse precuneiform nucleus has been proposed as the midbrain locomotion center, a function ascribed to its caudal neighbor, cuneiform nucleus, in the rat, cat and other species. The present study investigated the projections from the central amygdaloid nucleus to the precuneiform nucleus in the mouse using retrograde tracer injections (fluoro-gold) into the precuneiform nucleus and anterograde tracer injections (biotinylated dextran amine) into the central amygdaloid nucleus. The entire central amygdaloid nucleus except the rostral pole had retrogradely labeled neurons, especially in the middle portion where labeled neurons were densely packed. Anterogradely labeled amygdaloid fibers approached the precuneiform nucleus from the area ventrolateral to it and terminated in the entire precuneiform nucleus. Labeled fibers were also found in laminae 5 and 6 in the upper cervical cord on the ipsilateral side. The present study is the first demonstration of projections from the central amygdaloid nucleus to the precuneiform nucleus. This projection may underpin the role of the precuneiform nucleus in the modulation of the cardiovascular activity.

  8. The nature of the cometary nucleus

    NASA Technical Reports Server (NTRS)

    Delsemme, A. H.

    1985-01-01

    The basic properties of the cometary nucleus are reviewed. Consideration is given to the absence of depth differentiation, the icy conglomerate nature, the possible existence of a halo of icy grains around the nuclear region, the nucleus size and albedo, the mass, the rotation rate, and the chemical composition (elemental and molecular).

  9. 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

  10. 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.

  11. Correlation and fluctuations in relativistic nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Mohsin Khan, M.; Ahmad, N.; Kamal, A.; Masoodi, A. A.; Irfan, M.

    2011-01-01

    Correlation and fluctuations are now well accepted analysis techniques in heavy-ion collisions at relativistic energies. At the current stage of RHIC exploration, matter in bulk and many of the physics questions about the final stage of collisions are addressed with the help of correlation techniques. In the present work after a general introduction to the underlying formalism to the exotic phenomena of correlation and fluctuations, discussion on various parameters disentangling dynamical fluctuations is presented. Analysis to investigate dynamical fluctuations and correlation is carried out in terms of F q - and G q -moments. A study of various other parameters involving multiplicity and pseudorapidity of relativistic charged particles produced in high energy nuclear interactions reveals the presence of correlation and fluctuations in particle production in these collisions. The experimental data on 14.5A GeV/c 28Si-nucleus interactions has been analyzed. A parallel analysis of correlation free data generated using MC-RAND Monte Carlo code, UrQMD data and for the HIJING generated events has also been carried out.

  12. 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.

  13. The mediodorsal thalamic nucleus and schizophrenia

    PubMed Central

    Alelú-Paz, Raúl; Giménez-Amaya, José Manuel

    2008-01-01

    The mediodorsal nucleus of the human thalamus is in a crucial position that allows it to establish connections with diverse cerebral structures, particularly the prefrontal cortex. The present review examines existing neurobiologic studies of the brains of people with and without schizophrenia that indicate a possible involvement of the mediodorsal nucleus in this psychiatric disorder. Studies at synaptic and cellular levels of the neurobiology of the mediodorsal nucleus, together with a better anatomic understanding of this diencephalic structure owing to neuroimaging studies, should help to establish a more deep and solid pathophysiologic model of schizophrenia. PMID:18982171

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. BFKL Pomeron calculus: solution to equations for nucleus-nucleus scattering in the saturation domain

    NASA Astrophysics Data System (ADS)

    Contreras, Carlos; Levin, Eugene; Meneses, Rodrigo

    2013-04-01

    In this paper we solve the equation for nucleus-nucleus scattering in the BFKL Pomeron calculus, suggested by Braun [1-3]. We find these solutions analytically at high energies as well as numerically in the entire region of energies inside the saturation region. The semi-classical approximation is used to select out the infinite set of the parasite solutions. The nucleus-nucleus cross sections at high energy are estimated and compared with the Glauber-Gribov approach. It turns out that the exact formula gives the estimates that are very close to the ones based on Glauber-Gribov formula which is important for the practical applications.

  19. Dynamical evolution of comet nucleus rotation

    NASA Astrophysics Data System (ADS)

    Scheeres, D. J.; Sidorenko, V. V.; Neishtadt, A. I.; Vasiliev, A. A.

    2001-11-01

    The rotational dynamics of outgassing cometary nuclei are investigated analytically using dynamical systems theory. We develop a general theory for the averaged evolution of a comet nucleus rotation state assuming that the nucleus is a spheroid (either prolate or oblate) and that the outgassing torques are a function of solar insolation and heliocentric distance. The resulting solutions are a function of the comet outgassing properties, its heliocentric orbit, and the assumed distribution of active regions on its surface. We find that the long-term evolution of the comet nucleus rotation is a strong function of the distribution of active regions over its surface. Specifically, we find that a comet nucleus with a uniformly active surface will tend towards a rotation state with a nutation angle of ~ 55 degrees and an angular momentum perpendicular to the sun-perihelion direction. Conversely, a comet nucleus with an isolated active region will tend towards a zero nutation angle with its symmetry axis and angular momentum aligned parallel to the sun-perihelion direction. For active surface regions between these extremes we find 4 qualitatively different dynamical outcomes. In all cases, the theory predicts that the comet nucleus angular momentum will have a secular increase, a phenomenon that could contribute to nucleus splitting of active comets. These results can be used to discriminate between competing theories of comet outgassing based on a nucelus' rotation state. They also allow for a range of plausible a priori constraints to be placed on a comet's rotation state to aid in the interpretation of its outgassing structure. This work was supported by the NASA JURRISS program under Grant NAG5-8715. AIN, AAV and VVS acknowledge support from Russian Foundation for Basic research via Grants 00-01-00538 and 00-01-0174 respectively. DJS acknowledges support from the PG&G program via Grant NAG5-9017.

  20. High density QCD and nucleus-nucleus scattering deeply in the saturation region

    NASA Astrophysics Data System (ADS)

    Kormilitzin, Andrey; Levin, Eugene; Miller, Jeremy S.

    2011-06-01

    In this paper we solve the equations that describe nucleus-nucleus scattering, in high density QCD, in the framework of the BFKL Pomeron Calculus. We found that (i) the contribution of short distances to the opacity for nucleus-nucleus scattering dies at high energies, (ii) the opacity tends to unity at high energy, and (iii) the main contribution that survives comes from soft (long distance) processes for large values of the impact parameter. The corrections to the opacity Ω(Y,b)=1 were calculated and it turns out that they have a completely different form, namely ( 1-Ω→exp(-Const √{Y} )) than the opacity that stems from the Balitsky-Kovchegov equation, which is ( 1-Ω→exp(-Const Y)). We reproduce the formula for the nucleus-nucleus cross section that is commonly used in the description of nucleus-nucleus scattering, and there is no reason why it should be correct in the Glauber-Gribov approach.

  1. Target nucleus in relativistic nuclear collisions

    SciTech Connect

    Gutbrod, H.H.; Warwick, A.I.; Wieman, H.

    1982-03-01

    Both the fireball model and hydrodynamical model predict, in a central collision, a fast energy dissipation in the early diving stage of the projectile into the target nucleus. In the final state both models show total incident energy largely dispersed over the whole target nucleus. In a quantitative comparison with the data for the Intranuclear Cascade Calculations, however, the 90/sup 0/ double differential cross section seems to be flatter than the calculated one. If the slope is reflecting the temperature in the system then the data are having apparently a higher temperature than the cascade would predict. This report suggests and discusses a picture of the reaction mechanism where the light projectile (e.g. Ne) gets stopped very early in the large target nucleus (e.g. Au or U) forming a small fireball at approximately half the beam rapidity, which decays inside the target nucleus, heating it up and causing thee whole system to expand. The expansion cools the system and big clusters can condense out if the total energy and thus entropy in the system is not too high to prevent it. Such a qualitative picture of a reaction mechanism emerges when we consider the information obtained about relativistic nuclear collisions from measurements of the remnants of a large target nucleus struck by a smaller projectile (Ne + Au) and relate it to the complementary information from earlier measurements of fast light reaction products. (WHK)

  2. Cell Biology of the Caenorhabditis elegans Nucleus.

    PubMed

    Cohen-Fix, Orna; Askjaer, Peter

    2017-01-01

    Studies on the Caenorhabditis elegans nucleus have provided fascinating insight to the organization and activities of eukaryotic cells. Being the organelle that holds the genetic blueprint of the cell, the nucleus is critical for basically every aspect of cell biology. The stereotypical development of C. elegans from a one cell-stage embryo to a fertile hermaphrodite with 959 somatic nuclei has allowed the identification of mutants with specific alterations in gene expression programs, nuclear morphology, or nuclear positioning. Moreover, the early C. elegans embryo is an excellent model to dissect the mitotic processes of nuclear disassembly and reformation with high spatiotemporal resolution. We review here several features of the C. elegans nucleus, including its composition, structure, and dynamics. We also discuss the spatial organization of chromatin and regulation of gene expression and how this depends on tight control of nucleocytoplasmic transport. Finally, the extensive connections of the nucleus with the cytoskeleton and their implications during development are described. Most processes of the C. elegans nucleus are evolutionarily conserved, highlighting the relevance of this powerful and versatile model organism to human biology. Copyright © 2017 by the Genetics Society of America.

  3. Structural dynamics of the cell nucleus

    PubMed Central

    Wiegert, Simon; Bading, Hilmar

    2011-01-01

    Neuronal morphology plays an essential role in signal processing in the brain. Individual neurons can undergo use-dependent changes in their shape and connectivity, which affects how intracellular processes are regulated and how signals are transferred from one cell to another in a neuronal network. Calcium is one of the most important intracellular second messengers regulating cellular morphologies and functions. In neurons, intracellular calcium levels are controlled by ion channels in the plasma membrane such as NMDA receptors (NMDARs), voltage-gated calcium channels (VGCCs) and certain α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as well as by calcium exchange pathways between the cytosol and internal calcium stores including the endoplasmic reticulum and mitochondria. Synaptic activity and the subsequent opening of ligand and/or voltage-gated calcium channels can initiate cytosolic calcium transients which propagate towards the cell soma and enter the nucleus via its nuclear pore complexes (NPCs) embedded in the nuclear envelope. We recently described the discovery that in hippocampal neurons the morphology of the nucleus affects the calcium dynamics within the nucleus. Here we propose that nuclear infoldings determine whether a nucleus functions as an integrator or detector of oscillating calcium signals. We outline possible ties between nuclear mophology and transcriptional activity and discuss the importance of extending the approach to whole cell calcium signal modeling in order to understand synapse-to-nucleus communication in healthy and dysfunctional neurons. PMID:21738832

  4. Control of nucleus positioning in mouse oocytes.

    PubMed

    Almonacid, Maria; Terret, Marie-Emilie; Verlhac, Marie-Hélène

    2017-08-12

    The position of the nucleus in a cell can instruct morphogenesis in some cases, conveying spatial and temporal information and abnormal nuclear positioning can lead to disease. In oocytes from worm, sea urchin, frog and some fish, nucleus position regulates embryo development, it marks the animal pole and in Drosophila it defines the future dorso-ventral axis of the embryo and of the adult body plan. However, in mammals, the oocyte nucleus is centrally located and does not instruct any future embryo axis. Yet an off-center nucleus correlates with poor outcome for mouse and human oocyte development. This is surprising since oocytes further undergo two extremely asymmetric divisions in terms of the size of the daughter cells (enabling polar body extrusion), requiring an off-centering of their chromosomes. In this review we address not only the bio-physical mechanism controlling nucleus positioning via an actin-mediated pressure gradient, but we also speculate on potential biological relevance of nuclear positioning in mammalian oocytes and early embryos. Copyright © 2017. Published by Elsevier Ltd.

  5. 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.

  6. Organisation of the human dorsomedial hypothalamic nucleus.

    PubMed

    Koutcherov, Yuri; Mai, Juergen K; Ashwell, Ken W; Paxinos, George

    2004-01-19

    This study used acetylcholinesterase (AChE) histochemistry to reveal the organization of the dorsomedial hypothalamic nucleus (DM) in the human. Topographically, the human DM is similar to DM in the monkey and rat. It is wedged between the paraventricular nucleus, dorsally, and the ventromedial nucleus, ventrally. Laterally, DM borders the lateral hypothalamic area while medially it approaches the 3rd ventricle. The AChE staining distinguished two subcompartments of the human DM: the larger diffuse and the smaller compact DM. The subcompartmental organization of the human DM appears homologous to that found in the monkey and less complex than that reported in rats. Understanding of the organization of DM creates meaningful anatomical reference for physiological and pharmacological studies in the human hypothalamus.

  7. 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

  8. 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.

  9. 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

  10. Compound Nucleus Contributions to the Optical Potential

    SciTech Connect

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

    2008-04-17

    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.

  11. Pion-nucleon scattering and pion production in nucleon-nucleon and nucleus-nucleus collisions

    SciTech Connect

    Dover, C.B.

    1982-01-01

    Lecture notes are presented on the following: (1) basic aspects of ..pi..N interactions (properties of pions and nucleons, SU(3) and SU(6) classification phenomenology of ..pi..N scattering ((3.3) resonance; phase shift analysis, and bag model approach to ..pi..N); (2) pion production and absorption in the two nucleon system (NN ..-->.. NN..pi.. (isobar model) and ..pi..d reversible NN (existence of dibaryon resonances)); (3) pion absorption in complex nuclei (multiparticle aspects and cascade calculations); and (4) pion production with nuclear targets including (a) nucleon-nucleus, (b) nucleus-nucleus (Fermi-averaged 2-body vs thermodynamic models), and (c) ..pi pi.. interoferometry.

  12. 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.

  13. Two-photon physics in nucleus-nucleus collisions at RHIC

    SciTech Connect

    Nystrand, J.; Klein, S.

    1998-09-01

    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.

  14. Fermi-motion effect on the intermediate energy nucleus-nucleus collision

    NASA Astrophysics Data System (ADS)

    Fan, G. W.; Kong, W. Y.; Han, T. F.; Li, X. C.; Ma, J. B.; Sheng, Z. Q.; Shi, G. Z.; Tian, F.; Wang, J.; Zhang, C.

    2016-11-01

    The Glauber model is modified with the Fermi-motion effect in the calculation of elastic differential cross-sections and momentum distributions of a fragment from mother nucleus. Different reaction systems at low energies are calculated with the modified Glauber model. It is found that calculations including the Fermi-motion provide a better prescription relating the model to a proper nuclear density distribution by comparing with the experimental data. On the basis of the studies, the influence of the correction on the extracted nuclear radius is quantified. The results further confirm the importance of the Fermi-motion in the nucleus-nucleus collision reactions at low energies.

  15. 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.

  16. 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)

  17. Oral alprazolam acutely increases nucleus accumbens perfusion

    PubMed Central

    Wolf, Daniel H.; Pinkham, Amy E.; Satterthwaite, Theodore D.; Ruparel, Kosha; Elliott, Mark A.; Valdez, Jeffrey; Smith, Mark A.; Detre, John A.; Gur, Ruben C.; Gur, Raquel E.

    2014-01-01

    Benzodiazepines treat anxiety, but can also produce euphoric effects, contributing to abuse. Using perfusion magnetic resonance imaging, we provide the first direct evidence in humans that alprazolam (Xanax) acutely increases perfusion in the nucleus accumbens, a key reward-processing region linked to addiction. PMID:23070072

  18. THE ROLE OF THE NUCLEUS IN OXIDATION.

    PubMed

    Osterhout, W J

    1917-10-12

    Injury produces in the leaf-cells of the Indian Pipe (Monotropa uniflora) a darkening which is due to oxidation. The oxidation is much more rapid in the nucleus than in the cytoplasm and the facts indicate that this is also the case with the oxidation of the uninjured cell.

  19. Nucleon-nucleus interactions from JACEE

    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.

    1985-01-01

    Results on hadron-nucleus interactions from the Japanese-American Cooperation Emulsion Experiment experiment are presented. Angular distributions for charged particles, and angular and transverse momentum spectra for photons have been measured for a sample of events with sigma epsilon sub gamma. Results on central rapidity density and transverse energy flow are discussed.

  20. Nucleus-associated actin in Amoeba proteus.

    PubMed

    Berdieva, Mariia; Bogolyubov, Dmitry; Podlipaeva, Yuliya; Goodkov, Andrew

    2016-10-01

    The presence, spatial distribution and forms of intranuclear and nucleus-associated cytoplasmic actin were studied in Amoeba proteus with immunocytochemical approaches. Labeling with different anti-actin antibodies and staining with TRITC-phalloidin and fluorescent deoxyribonuclease I were used. We showed that actin is abundant within the nucleus as well as in the cytoplasm of A. proteus cells. According to DNase I experiments, the predominant form of intranuclear actin is G-actin which is associated with chromatin strands. Besides, unpolymerized actin was shown to participate in organization of a prominent actin layer adjacent to the outer surface of nuclear envelope. No significant amount of F-actin was found in the nucleus. At the same time, the amoeba nucleus is enclosed in a basket-like structure formed by circumnuclear actin filaments and bundles connected with global cytoplasmic actin cytoskeleton. A supposed architectural function of actin filaments was studied by treatment with actin-depolymerizing agent latrunculin A. It disassembled the circumnuclear actin system, but did not affect the intranuclear chromatin structure. The results obtained for amoeba cells support the modern concept that actin is involved in fundamental nuclear processes that have evolved in the cells of multicellular organisms.

  1. New developments in nucleus pulposus replacement technology.

    PubMed

    Carl, Allen; Ledet, Eric; Yuan, Hansen; Sharan, Alok

    2004-01-01

    Attempts to alleviate the pain attributed to degeneration of the nucleus pulposus using replacement or reinforcement techniques dating back to the 1950s are reviewed. The various materials and their insertion techniques are discussed as are results available from early clinical experiences. These techniques are in evolution and clinical outcomes will be necessary to establish the efficacy of these approaches.

  2. 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.

  3. 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.

  4. Results on ultra-relativistic nucleus-nucleus interactions from balloon-borne emulsion chambers

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Derrickson, J. H.; Fountain, W.; Meegan, C. A.; Takahashi, Y.; Watts, J. W.; Fuki, M.; Gregory, J. C.; Hayashi, T.

    1985-01-01

    The results of balloon-borne emulsion-chamber measurements on high-energy cosmic-ray nuclei (Burnett et al., 1983) are summarized in tables and graphs and briefly characterized. Special consideration is given to seven nucleus-nucleus interaction events at energy in excess of 1 TeV/A with multiplicity greater than 400, and to Fe interactions (53 with CHO, 10 with emulsion, and 14 with Pb) at 20-60 GeV/A.

  5. Ventral nucleus of the lateral lemniscus in guinea pigs: cytoarchitecture and inputs from the cochlear nucleus.

    PubMed

    Schofield, B R; Cant, N B

    1997-03-17

    Cytoarchitectonic criteria were used to distinguish three subdivisions of the ventral nucleus of the lateral lemniscus in guinea pigs. Axonal tracing techniques were used to examine the projections from the cochlear nucleus to each subdivision. Based on the cell types they contain and their patterns of input, we distinguished ventral, dorsal, and anterior subdivisions of the ventral nucleus of the lateral lemniscus. All three subdivisions receive bilateral inputs from the cochlear nucleus, with contralateral inputs greatly outnumbering ipsilateral inputs. However, the relative density of the inputs varies: the ventral subdivision receives the densest projection, whereas the anterior subdivision receives the sparsest projection. Further differences are apparent in the morphology of the afferent axons. Following an injection of Phaseolus vulgaris-leucoagglutinin into the ventral cochlear nucleus, most of the axons on the contralateral side and all of the axons on the ipsilateral side are thin. Thick axons are present only in the ventral subdivision contralateral to the injection site. The evidence from both anterograde and retrograde tracing studies suggests that the thick axons originate from octopus cells, whereas the thin axons arise from multipolar cells and spherical bushy cells. The differences in constituent cell types and in patterns of inputs suggest that each of the three subdivisions of the ventral nucleus of the lateral lemniscus makes a distinct contribution to the analysis of acoustic signals.

  6. 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). © 2015 Wiley Periodicals, Inc.

  7. Why do we have a caudate nucleus?

    PubMed

    Villablanca, Jaime R

    2010-01-01

    In order to understand the physiological role of the caudate nucleus, we combine here our laboratory data on cats with reports of patients with selective damage to this nucleus. Cats with bilateral removal of the caudate nuclei showed a stereotyped behavior consisting of persistently approaching and then following a person, another cat, or any object, and attempting to contact the target. Simultaneously, the animals exhibited a friendly disposition and persistent docility together with purring and forelimbs treading/kneading. The magnitude and duration of this behavior was proportional to the extent of the removal reaching a maximum after ablations of 65% or more of the caudate tissue. These cats were hyperactive but they had lost the feline elegance of movements. Additional features of acaudate cats were: (1) postural and accuracy deficits (plus perseveration) in paw usage tasks including bar pressing for food reward; (2) cognitive and perceptual impairments on a T-maze battery of tasks and on the bar pressing tasks; (3) blockage or blunting of the species-specific behavioral response to a single injection of morphine; Unilateral caudate nucleus removal did not produce global behavioral effects, but only deficit in the contralateral paw contact placing reaction and paw usage/bar pressing. Moreover and surprisingly, we found hypertrophy of the ipsilateral caudate nucleus following prenatal focal neocortical removal. The findings in human were also behavioral (not neurological) and also occurred with unilateral caudate damage. The main manifestations consisted of loss of drive (apathy), obsessive-compulsive behavior, cognitive deficits, stimulus-bound perseverative behavior, and hyperactivity. Based on all of the above data we propose that the specific function of the caudate nucleus is to control approach-attachment behavior, ranging from plain approach to a target, to romantic love. This putative function would account well for the caudate involvement in the

  8. Collateral projections from the lateral parabrachial nucleus to the paraventricular thalamic nucleus and the central amygdaloid nucleus in the rat.

    PubMed

    Liang, Shao-Hua; Yin, Jun-Bin; Sun, Yi; Bai, Yang; Zhou, Kai-Xiang; Zhao, Wen-Jun; Wang, Wei; Dong, Yu-Lin; Li, Yun-Qing

    2016-08-26

    Combined the retrograde double tracing with immunofluorescence histochemical staining, we examined the neurons in the lateral parabrachial nucleus (LPB) sent collateral projections to the paraventricular thalamic nucleus (PVT) and central amygdaloid nucleus (CeA) and their roles in the nociceptive transmission in the rat. After the injection of Fluoro-gold (FG) into the PVT and tetramethylrhodamine-dextran (TMR) into the CeA, respectively, FG/TMR double-labeled neurons were observed in the LPB. The percentages of FG/TMR double-labeled neurons to the total number of FG- or TMR-labeled neurons were 6.18% and 9.09%, respectively. Almost all of the FG/TMR double-labeled neurons (95%) exhibited calcitonin gene-related peptide (CGRP) immunoreactivity. In the condition of neuropathic pain, 94% of these neurons showed FOS immunoreactivity. The present data indicates that some of CGRP-expressing neurons in the LPB may transmit nociceptive information toward the PVT and CeA by way of axon collaterals.

  9. Feasibility of multichannel human cochlear nucleus stimulation.

    PubMed

    Luetje, C M; Whittaker, C K; Geier, L; Mediavilla, S J; Shallop, J K

    1992-01-01

    Bipolar electrical stimulation of the brainstem cochlear nucleus (CN) following acoustic tumor removal in an only-hearing ear can provide beneficial hearing. However, the benefits of multichannel stimulation have yet to be defined. Following removal of a second acoustic tumor in a patient with neurofibromatosis 2, a Nucleus mini-22 channel implant device was inserted with the electrode array tip from the foramen of Luschka cephalad along the root entry zone of the eighth nerve, secured by a single suture superficially in the brain stem. Initial stimulation on the sixth postoperative day indicated that electrodes 18 to 22 were capable of CN stimulation without seventh nerve stimulation. Presumed electrode migration precluded further CN stimulation 1 month later. This report illustrates the feasibility of brainstem CN stimulation with an existing multichannel system.

  10. 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

  11. 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.

  12. Gustatory Reward and the Nucleus Accumbens

    PubMed Central

    Norgren, R.; Hajnal, A.; Mungarndee, S.S.

    2011-01-01

    The concept of reward is central to psychology, but remains a cipher for neuroscience. Considerable evidence implicates dopamine in the process of reward and much of the data derives from the nucleus accumbens. Gustatory stimuli are widely used for animal studies of reward, but the connections between the taste and reward systems are unknown. In a series of experiments, our laboratory has addressed this issue using functional neurochemistry and neuroanatomy. First, using microdialysis probes, we demonstrated that sapid sucrose releases dopamine in the nucleus accumbens. The effect is dependent on oral stimulation and concentration. We subsequently determined that this response was independent of the thalamocortical gustatory system, but substantially blunted by damage to the parabrachial limbic taste projection. Further experiments using c-fos histochemistry confirmed that the limbic pathway was the prime carrier for the gustatory afferent activity that drives accumbens dopamine release. PMID:16822531

  13. Finite nucleus effects on relativistic energy corrections

    NASA Technical Reports Server (NTRS)

    Dyall, Kenneth G.; Faegri, Knut, Jr.

    1993-01-01

    The effect of using a finite nucleus model in quantum-chemical calculations is examined. Relativistic corrections from the first order Foldy-Wouthuysen terms are affected indirectly by the change in wavefunction, but also directly as a result of revised expressions for the Darwin and spin-orbit terms due to the change in nuclear potential. A calculation for the Rn atom indicates that the mass-velocity and Darwin corrections are much more sensitive to the finite nucleus than the non-relativistic total energy, but that the total contribution for these two terms is quite stable provided the revised form of the Darwin term is used. The spin-orbit interaction is not greatly affected by the choice of nuclear model.

  14. 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.

  15. 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.

  16. 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°C, and a single stage system can operate the warm wall at -45C. 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.

  17. Pygmy dipole response in 238U nucleus

    NASA Astrophysics Data System (ADS)

    Guliyev, Ekber; Kuliev, Ali Akbar; Quliyev, Huseynqulu

    2017-02-01

    The presence of the El pygmy dipole resonance (PDR) in the actinide nucleus 238U was shown via QRPA. Below the particle threshold energy, 24 excitation states were calculated. The calculations, is demonstrating the presence of a PDR with evidence for K splitting. The calculations further suggest that the PDR in 238U is predominantly K=0. The obtained results show universality of the PDR in atomic nuclei.

  18. Absolute cross sections of compound nucleus reactions

    NASA Astrophysics Data System (ADS)

    Capurro, O. A.

    1993-11-01

    The program SEEF is a Fortran IV computer code for the extraction of absolute cross sections of compound nucleus reactions. When the evaporation residue is fed by its parents, only cumulative cross sections will be obtained from off-line gamma ray measurements. But, if one has the parent excitation function (experimental or calculated), this code will make it possible to determine absolute cross sections of any exit channel.

  19. Antinucleon-nucleus elastic and inelastic scattering

    SciTech Connect

    Dover, C.B.; Millener, D.J.

    1985-01-01

    A general overview of the utility of antinucleon (anti N)-nucleus inelastic scattering studies is presented, emphasizing both the sensitivity of the cross sections to various components of the N anti N transition amplitudes and the prospects for the exploration of some novel aspects of nuclear structure. We start with an examination of the relation between NN and N anti N potentials, focusing on the coherences predicted for the central, spin-orbit and tensor components, and how these may be revealed by measurements of two-body spin observables. We next discuss the role of the nucleus as a spin and isospin filter, and show how, by a judicious choice of final state quantum numbers (natural or unnatural parity states, isospin transfer ..delta..T = 0 or 1) and momentum transfer q, one can isolate different components of the N anti N transition amplitude. Various models for the N anti N interaction which give reasonable fits to the available two-body data are shown to lead to strikingly different predictions for certain spin-flip nuclear transitions. We suggest several possible directions for future anti N-nucleus inelastic scattering experiments, for instance the study of spin observables which would be accessible with polarized anti N beams, charge exchange reactions, and higher resolution studies of the (anti p, anti p') reaction. We compare the antinucleon and the nucleon as a probe of nuclear modes of excitation. 40 refs., 13 figs.

  20. 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.

  1. How to build a yeast nucleus.

    PubMed

    Wong, Hua; Arbona, Jean-Michel; Zimmer, Christophe

    2013-01-01

    Biological functions including gene expression and DNA repair are affected by the 3D architecture of the genome, but the underlying mechanisms are still unknown. Notably, it remains unclear to what extent nuclear architecture is driven by generic physical properties of polymers or by specific factors such as proteins binding particular DNA sequences. The budding yeast nucleus has been intensely studied by imaging and biochemical techniques, resulting in a large quantitative data set on locus positions and DNA contact frequencies. We recently described a quantitative model of the interphase yeast nucleus in which chromosomes are represented as passively moving polymer chains. This model ignores the DNA sequence information except for specific constraints at the centromeres, telomeres, and the ribosomal DNA (rDNA). Despite its simplicity, the model accounts for a large majority of experimental data, including absolute and relative locus positions and contact frequency patterns at chromosomal and subchromosomal scales. Here, we also illustrate the model's ability to reproduce observed features of chromatin movements. Our results strongly suggest that the dynamic large-scale architecture of the yeast nucleus is dominated by statistical properties of randomly moving polymers with a few sequence-specific constraints, rather than by a large number of DNA-specific factors or epigenetic modifications. In addition, we show that our model accounts for recently measured variations in homologous recombination efficiency, illustrating its potential for quantitatively understanding functional consequences of nuclear architecture.

  2. Theoretical predictions for the nucleus 296118

    NASA Astrophysics Data System (ADS)

    Sobiczewski, A.

    2016-11-01

    Theoretical predictions for the α -decay chain of the nucleus 296118 are performed. The synthesis of this nucleus is being attempted in experiments running in Dubna. The α -decay energies Qα, and the α -decay and spontaneous-fission half-lives, Tα and Tsf, are studied. The analysis of the α decay is based on a phenomenological model using only three parameters. The calculations are performed in nine variants using masses obtained within nine nuclear-mass models describing masses of the heaviest nuclei. The experimental Qα energies, known from earlier experiments for the potential daughter, 292Lv, and grand-daughter, 288Fl, nuclei are reproduced with an average of the absolute values of the discrepancies: from 0.13 to 1.52 MeV within the considered variants. Measured half-lives Tα are reconstructed within average ratios: from 1.7 to 1054. Within all variants considered, the half-life Tα of the nucleus 296118 is obtained larger than needed (around 1 μ s ) for its observation.

  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. Copyright 1999 Academic Press.

  4. 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.

  5. Is {sup 276}U a doubly magic nucleus?

    SciTech Connect

    Liliani, N. Sulaksono, A.

    2016-04-19

    We investigate a possible new doubly magic heavy nucleus by using a relativistic mean-field (RMF) model with the addition of a cross interaction term of omega-rho mesons and an electromagnetic exchange term. We propose that {sup 276}U is a doubly magic nucleus. The evidence for {sup 276}U being a doubly magic nucleus is shown through the two-nucleon gaps, the single-particle energies, and the neutron skin thickness of the nucleus. We have also found that the prediction of {sup 276}U as a doubly magic nucleus by the RMF model is not affected by the inclusion of isoscalar-isovector and electromagnetic exchange couplings.

  6. Dynamical evolution of comet nucleus rotation

    NASA Astrophysics Data System (ADS)

    Scheeres, D. J.; Sidorenko, V. V.; Neishtadt, A. I.; Vasiliev, A. A.

    2002-09-01

    The rotational dynamics of outgassing cometary nuclei are investigated analytically. We develop a general theory for the evolution of a comet nucleus' rotation state using averaging theory and assuming that the outgassing torques are a function of solar insolation and heliocentric distance. The resulting solutions are a function of the nucleus inertia ellipsoid, its outgassing properties, its heliocentric orbit, and the assumed distribution of active regions on its surface. We find that the long-term evolution of the comet nucleus rotation is a strong function of the distribution of active regions over its surface. In particular, we find that nuclei with nearly axisymmetric inertia ellipsoids and a uniformly active surface will tend towards a rotation state that has a nutation angle of ~ 55 degrees and its angular momentum perpendicular to the sun-perihelion direction. If such a comet nucleus has only one isolated active region, it will tend towards a zero nutation angle with its approximate symmetry axis and rotational angular momentum aligned parallel to the sun-perihelion direction. In the general case for an inertia ellipsoid that is not close to being axisymmetric we find a much richer set of possible steady-state solutions that are stable, ranging from rotation about the maximum moment of the inertia axis, to SAM and LAM non-principal axis rotation states. The resulting stable rotation states are a strong function of outgassing activity distribution, which we show using a simplified model of the comet Halley nucleus. Also, we demonstrate that comet Borrely observations are consistent with a stable rotation state. Our results can be used to discriminate between competing theories of comet outgassing based on a nucelus' rotation state. They also allow for a range of plausible a priori constraints to be placed on a comet's rotation state to aid in the interpretation of its outgassing structure. This work was supported by the NASA JURRISS program under Grant NAG5

  7. 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.

  8. The effect of the relative nuclear size on the nucleus-nucleus interactions

    NASA Technical Reports Server (NTRS)

    Erofeeva, I. N.; Murzin, V. S.; Sivoklokov, S. Y.; Smirnova, L. N.

    1985-01-01

    The experimental data on the interactions of light nuclei (d, He(4), C(12)) at the momentum 4.2 GeV/cA with the carbon nuclei were taken in the 2-m propane bubble chamber. The distributions in the number of interacting nucleons, the spectra of protons, the mean energies of secondary pions and protons, the mean fractions of energy transferred to the pion and nucleon components are presented. The results of the investigation of the mechanism of nucleus-nucleus interactions can be used to calculate the nuclear cascades in the atmosphere.

  9. 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.

  10. 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.

  11. Subthreshold pion production from nucleus-nucleus collisions around 100 MeV/nucleon

    NASA Astrophysics Data System (ADS)

    Badalá, A.; Barbera, R.; Palmeri, A.; Pappalardo, G. S.; Riggi, F.; Russo, A. C.

    1993-12-01

    Several global variables were tested with the aim to determine the impact parameter in nucleus-nucleus collisions producing pions at incident energies around 100 MeV/nucleon. The experimental set-up includes the MEDEA multidetector, part of which is used as a π 0 spectrometer, and an additional hodoscope of plastic scintillators to cover very forward angles. A statistical model was used to generate both inclusive and pion-triggered events. Selection of well measured events was made through the measured total parallel momentum. Among the different global variables which were tested, the average parallel velocity was seen to give the best correlation with the impact parameter.

  12. Jet Tomography of High-Energy Nucleus-Nucleus Collisions at Next-to-Leading Order

    NASA Astrophysics Data System (ADS)

    Vitev, Ivan; Zhang, Ben-Wei

    2010-04-01

    We demonstrate that jet observables are highly sensitive to the characteristics of the vacuum and the in-medium QCD parton showers and propose techniques that exploit this sensitivity to constrain the mechanism of quark and gluon energy loss in strongly interacting plasmas. As a first example, we calculate the inclusive jet cross section in high-energy nucleus-nucleus collisions to O(αs3). Theoretical predictions for the medium-induced jet broadening and the suppression of the jet production rate due to cold and hot nuclear matter effects in Au+Au and Cu+Cu reactions at RHIC are presented.

  13. Jet tomography of high-energy nucleus-nucleus collisions at next-to-leading order

    SciTech Connect

    Vitev, Ivan; Zhang, Ben - Wei

    2009-01-01

    We demonstrate that jet observables are highly sensitive to the characteristics of the vacuum and the in-medium QCD parton showers and propose techniques that exploit this sensitivity to constrain the mechanism of quark and gluon energy loss in strongly-interacting plasmas. As a first example, we calculate the inclusive jet cross section in high-energy nucleus-nucleus collisions to {Omicron}({alpha}{sub s}{sup 3}). Theoretical predictions for the medium-induced jet broadening and the suppression of the jet production rate due to cold and hot nuclear matter effects in Au+Au and Cu+Cu reactions at RHIC are presented.

  14. Development of silicon pixels for strangeness detection in nucleus-nucleus collisions

    SciTech Connect

    Antinori, F. |; Barberis, D.; Beker, H.; Beusch, W.; Campbell, M.; Cantatore, E.; Catanesi, M.G.; Chesi, E.; Darbo, G.; Di Bari, D.; Di Liberto, S.; Elia, D.; Heijne, E.H.M.; Helstrup, H.; Jacholkowski, A.; Klempt, W.; Knudson, K.; Kralik, I.; Lassalle, J.C.; Lenti, V.; Lopez, L.; Luptak, M.; Martinengo, P.; Meddi, F.; Middelkamp, P.; Presented by...

    1995-07-20

    Silicon microdetectors and in particular the novel silicon pixel detectors open up the way for a comprehensive study of strangeness detection in nucleus-nucleus collisions. We outline the philosophy behind this approach, describe an application in the pixel-based heavy-ion experiment WA97, and give some preliminary results on the performance of four silicon pixels planes in the 1994 Pb beam run of WA97. We conclude with an outlook on some possible future applications of silicon pixels. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.

  15. 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.

  16. Pion cross section parametrizations for intermediate energy, nucleus-nucleus collisions

    SciTech Connect

    Norbury, John W.

    2009-03-15

    Space radiation and cosmic ray transport codes require simple and accurate models for hadron production in intermediate energy, nucleus-nucleus collisions. Several arithmetic parametrization models for pion production are compared to laboratory frame data. It is found that models based on high energy parametrizations are unable to describe intermediate energy, differential cross section data. However, simple thermal model parametrizations, when appropriately transformed from the center of momentum to the laboratory frame, are able to account for the data. Heavy ion transport codes that require algebraic cross section formulas can therefore use arithmetic parametrizations at high energy, but should use thermal model parametrizations at intermediate energy.

  17. Analysis of nucleus-nucleus collisions at high energies and random matrix theory

    SciTech Connect

    Nazmitdinov, R. G.; Shahaliev, E. I.; Suleymanov, M. K.; Tomsovic, S.

    2009-05-15

    We propose a novel statistical approach to the analysis of experimental data obtained in nucleus-nucleus collisions at high energies which borrows from methods developed within the context of random matrix theory. It is applied to the detection of correlations in a system of secondary particles. We find good agreement between the results obtained in this way and a standard analysis based on the method of effective mass spectra and two-pair correlation function often used in high energy physics. The method introduced here is free from unwanted background contributions.

  18. Surface Photometric Variation of Comet Borrelly's Nucleus

    NASA Astrophysics Data System (ADS)

    Li, J.; A'Hearn, M. F.; McFadden, L. A.

    2004-11-01

    Comet Borrelly was visited by Deep Space 1 in Sept. 2001 (Soderblom et al. 2004) The images of comet Borrelly's nucleus show large brightness variation over the surface even after the effect of shape is taken into account (Oberst et al. 2004, Kirk et al. 2004). It is not yet known whether this variation is caused by albedo variation (Oberst et al. 2004, Buratti et al. 2004) or the variation of other physical properties such as surface roughness (Kirk et al. 2004) or solar phase function. In our analysis, the disk-resolved images from the DS1 spacecraft (Soderblom et al. 2004) were used, coupled with the shape model of Borrelly's nucleus developed from stereo imaging (Oberst et al. 2004, Kirk et al. 2004), to fit the bidirectional reflectance as a function of local illumination and viewing geometry for individual terrains as defined by Britt et al. (2004). Results show that the surface reflectance variation is, contrary to previous interpretations, most likely due to the combination of albedo variation (a factor of 1.5) and the variation of the asymmetry factor (g) of the single-particle phase function. We find the roughness parameter (theta_bar) is <25o over the surface. The surface on Borrelly's nucleus can be highly back-scattering (g <= -0.7) for mottled terrain, and close to isotropic scattering (g -0.15) for smooth terrain, with single scattering albedo ranging from 0.05 to 0.07. This work is supported by NASA grant NNG04GA92G.

  19. 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.

  20. 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.

  1. Rethinking temperature sensitivity of the suprachiasmatic nucleus.

    PubMed

    Ruby, Norman F

    2011-08-01

    A report by Buhr et al. (2010) proposed that the suprachiasmatic nucleus (SCN) is resistant to phase shifts induced by heat pulses and to entrainment by temperature cycles. These findings are inconsistent with those from studies by other laboratories in which the SCN readily phase shifts in response to heat pulses. I propose that their negative findings are not due to the SCN being temperature insensitive but are based on an explant culture preparation that does not fully express the properties of the SCN that are present in other in vitro preparations.

  2. Galaxy NGC 1448 with Active Galactic Nucleus

    NASA Image and Video Library

    2017-01-07

    NGC 1448, a galaxy with an active galactic nucleus, is seen in this image combining data from the Carnegie-Irvine Galaxy Survey in the optical range and NuSTAR in the X-ray range. This galaxy contains an example of a supermassive black hole hidden by gas and dust. X-ray emissions from NGC 1448, as seen by NuSTAR and Chandra, suggests for the first time that, like IC 3639 in PIA21087, there must be a thick layer of gas and dust hiding the active black hole in this galaxy from our line of sight. http://photojournal.jpl.nasa.gov/catalog/PIA21086

  3. 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.

  4. The bare nucleus of comet Neujmin 1

    NASA Technical Reports Server (NTRS)

    Campins, Humberto; A'Hearn, Michael F.; Mcfadden, Lucy-Ann

    1987-01-01

    Simultaneous visible and infrared observations of comet P/Neujmin 1 1984c are presented which show that the comet has a large (mean radius 10 km), dark (geometric albedo 2-3 percent) nucleus with a surface which is mostly inert material but which still shows a low level of gaseous activity. This is the first physical evidence that cometary nuclei can leave behind an inert body after the coma activity ceases. No asteroid or asteroid class has been found to match the reflectance and albedo of this comet except possibly some D asteroids.

  5. [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.

  6. Visual field topography and binocular responses in frog's nucleus isthmi.

    PubMed

    Wang, S R; Yan, K; Wang, Y T

    1981-09-01

    Visual responses of 125 units have been extracellularly recorded with glass micropipettes from the left nucleus isthmi in the frog Rana nigromaculata, and 101 electrode tip positions marked with cobalt staining to reconstruct a visual field map in the nucleus. 80% of the units recorded show ON-OFF responses to a stationary spot of light and many are directionally selective in response to black or white targets moving through their receptive fields. All the cobalt-marked spots are within the nucleus, indicating that the nucleus isthmus proper is a restricted part of the frog visual system. There is a visual field map in the nucleus. The entire contralateral hemifield and the nasal 40 degrees of the ipsilateral hemifield project on the nucleus topographically. A cell-free band inside the nucleus is a boundary line separating the contralateral hemifield from the ipsilateral one. Dorsal to it is the contralateral field representation. The upper visual field projects on the rostral half of the nucleus and the central and medio-ventral portion of its caudal half. The lower field is represented on the dorsal and lateral part of the caudal half. Fifteen binocular units have been found from the nucleus, 13 of which are dominantly activated by the contralateral eye, the other two are almost equally excited by either eye. These binocular units are mainly situated in the medulla of the rostral half of the nucleus isthmus.

  7. The shape of the human lens nucleus with accommodation.

    PubMed

    Hermans, Erik; Dubbelman, Michiel; van der Heijde, Rob; Heethaar, Rob

    2007-07-31

    Knowledge about geometric properties such as shape and volume and Poisson's ratio of the nucleus can be used in the mechanical and optical modeling of the accommodation process. Therefore, Scheimpflug imaging was used to determine the shape of the human lens nucleus during accommodation in five subjects. To describe the shape of the nucleus, we fitted a parametric model of the cross-sectional geometry to the gradient of the Scheimpflug images using the Hough transform. The geometric model made it possible to estimate the anterior and the posterior central radius, central thickness, equatorial diameter, and cross-sectional area of the nucleus. Assuming that the nucleus is rotationally symmetric, the volume of the nucleus can be estimated by integrating around the circumference. For all five subjects, the results show that during accommodation the nucleus became more convex and that the central thickness increased whereas the equatorial diameter decreased. This decrease in equatorial diameter of the nucleus with accommodation is in accordance with the Helmholtz accommodation theory. Finally, the volume of the nucleus (on average 35 mm(3)) showed no significant change during accommodation in any of the subjects, presumably due to the fact that the human nucleus consists of incompressible material with a Poisson's ratio that is near .5.

  8. 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

  9. 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.

  10. Prestress mediates force propagation into the nucleus

    SciTech Connect

    Hu Shaohua; Chen Jianxin; Butler, James P.; Wang Ning . E-mail: nwang@hsph.harvard.edu

    2005-04-08

    Several reports show that the nucleus is 10 times stiffer than the cytoplasm. Hence, it is not clear if intra-nuclear structures can be directly deformed by a load of physiologic magnitudes. If a physiologic load could not directly deform intra-nuclear structures, then signaling inside the nucleus would occur only via the mechanisms of diffusion or translocation. Using a synchronous detection approach, we quantified displacements of nucleolar structures in cultured airway smooth muscle cells in response to a localized physiologic load ({approx}0.4 {mu}m surface deformation) via integrin receptors. The nucleolus exhibited significant displacements. Nucleolar structures also exhibited significant deformation, with the dominant strain being the bulk strain. Increasing the pre-existing tensile stress (prestress) in the cytoskeleton significantly increased the stress propagation efficiency to the nucleolus (defined as nucleolus displacement per surface deformation) whereas decreasing the prestress significantly lowered the stress propagation efficiency to the nucleolus. Abolishing the stress fibers/actin bundles by plating the cells on poly-L-lysine-coated dishes dramatically inhibited stress propagation to the nucleolus. These results demonstrate that the prestress in the cytoskeleton is crucial in mediating stress propagation to the nucleolus, with implications for direct mechanical regulation of nuclear activities and functions.

  11. Subthalamic Nucleus Stimulation Modulates Thalamic Neuronal Activity

    PubMed Central

    Xu, Weidong; Russo, Gary S.; Hashimoto, Takao; Zhang, Jianyu; Vitek, Jerrold L.

    2009-01-01

    Deep brain stimulation (DBS) in the subthalamic nucleus (STN) is an effective tool for the treatment of advanced Parkinson’s disease. The mechanism by which STN DBS elicits its beneficial effect, however, remains unclear. We previously reported STN stimulation increased the rate and produced a more regular and periodic pattern of neuronal activity in the internal segment of the globus pallidus (GPi). Here we extend our observations to neurons in the pallidal (ventralis lateralis pars oralis (VLo) and ventralis anterior (VA)) and cerebellar (ventralis lateralis posterior pars oralis (VPLo)) receiving areas of the motor thalamus during STN DBS. Stimulation parameters that produced improvement in rigidity and bradykinesia resulted in changes in the pattern and power of oscillatory activity of neuronal activity that were similar in both regions of the motor thalamus. Neurons in both VA/VLo and VPLo tended to become more periodic and regular with a shift in oscillatory activity from low to high frequencies. Burst activity was reduced in VA/VLo, but was not significantly changed in VPLo. There was also a significant shift in the population of VA/VLo neurons that were inhibited during STN DBS, while VPLo neurons tended to be activated. These data are consistent with the hypothesis that STN DBS increases output from the nucleus and produces a change in the pattern and periodicity of neuronal activity in the basal ganglia thalamic network, and that these changes include cerebellar pathways likely via activation of adjacent cerebello-thalamic fiber bundles. PMID:19005057

  12. Remote fitting in Nucleus cochlear implant recipients.

    PubMed

    Wesarg, Thomas; Wasowski, Arkadiusz; Skarzynski, Henryk; Ramos, Angel; Falcon Gonzalez, Juan Carlos; Kyriafinis, George; Junge, Friederike; Novakovich, Allan; Mauch, Herbert; Laszig, Roland

    2010-12-01

    Remote programming is a viable alternative to face-to-face programming. The procedure can be regarded as safe, time and cost saving, and clinically feasible. The aim of this study was to determine the suitability of commercially available video conferencing technology and remote control software for remote programming of sound processors in Nucleus cochlear implant recipients by assessing the feasibility, efficiency, risks, and benefits of remote programming compared to face-to-face programming. This was a randomized, prospective study. Seventy Nucleus implant recipients were recruited for a random sequence comparison of one remote and one local programming session each. The time required for local or remote programming was measured and resulting MAP T and C levels were compared. The recipient provided feedback on the local and remote programming session. The audiologist and monitoring clinician were asked for their feedback on remote programming. Remote programming sessions were successfully finished for 69 recipients. No significant differences between T and C levels obtained by local and remote programming were found. The audiologists and monitoring clinicians agreed that the remote programming system provided an acceptable level of performance after most sessions. More than 50 participating recipients considered remote programming an efficient alternative to face-to-face-programming.

  13. Comet nucleus and asteroid sample return missions

    NASA Technical Reports Server (NTRS)

    Melton, Robert G.; Thompson, Roger C.; Starchville, Thomas F., Jr.; Adams, C.; Aldo, A.; Dobson, K.; Flotta, C.; Gagliardino, J.; Lear, M.; Mcmillan, C.

    1992-01-01

    During the 1991-92 academic year, the Pennsylvania State University has developed three sample return missions: one to the nucleus of comet Wild 2, one to the asteroid Eros, and one to three asteroids located in the Main Belt. The primary objective of the comet nucleus sample return mission is to rendezvous with a short period comet and acquire a 10 kg sample for return to Earth. Upon rendezvous with the comet, a tethered coring and sampler drill will contact the surface and extract a two-meter core sample from the target site. Before the spacecraft returns to Earth, a monitoring penetrator containing scientific instruments will be deployed for gathering long-term data about the comet. A single asteroid sample return mission to the asteroid 433 Eros (chosen for proximity and launch opportunities) will extract a sample from the asteroid surface for return to Earth. To limit overall mission cost, most of the mission design uses current technologies, except the sampler drill design. The multiple asteroid sample return mission could best be characterized through its use of future technology including an optical communications system, a nuclear power reactor, and a low-thrust propulsion system. A low-thrust trajectory optimization code (QuickTop 2) obtained from the NASA LeRC helped in planning the size of major subsystem components, as well as the trajectory between targets.

  14. 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.

  15. Spectrin repeat proteins in the nucleus.

    PubMed

    Young, Kevin G; Kothary, Rashmi

    2005-02-01

    Spectrin repeat sequences are among the more common repeat elements identified in proteins, typically occurring in large structural proteins. Examples of spectrin repeat-containing proteins include dystrophin, alpha-actinin and spectrin itself--all proteins with well-demonstrated roles of establishing and maintaining cell structure. Over the past decade, it has become clear that, although these proteins display a cytoplasmic and plasma membrane distribution, several are also found both at the nuclear envelope, and within the intranuclear space. In this review, we provide an overview of recent work regarding various spectrin repeat-containing structural proteins in the nucleus. As well, we hypothesize about the regulation of their nuclear localization and possible nuclear functions based on domain architecture, known interacting proteins and evolutionary relationships. Given their large size, and their potential for interacting with multiple proteins and with chromatin, spectrin repeat-containing proteins represent strong candidates for important organizational proteins within the nucleus. Supplementary material for this article can be found on the BioEssays website (http://www.interscience.wiley.com/jpages/0265-9247/suppmat/index.html).

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

    NASA Technical Reports Server (NTRS)

    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.

  17. A search for ϕ meson nucleus bound state using antiproton annihilation on nucleus

    NASA Astrophysics Data System (ADS)

    Ohnishi, H.; Bühler, P.; Cargnelli, M.; Curceanu, C.; Guaraldo, C.; Hartmann, O.; Hicks, K.; Iwasaki, M.; Ishiwatari, T.; Kienle, P.; Marton, J.; Muto, R.; Naruki, M.; Niiyama, M.; Noumi, H.; Okada, S.; Vidal, A. Romero; Sakaguchi, A.; Sakuma, F.; Sawada, S.; Sirghi, D.; Sirghi, F.; Suzuki, K.; Tsukada, K.; Doce, O. Vazquez; Widmann, E.; Yokkaichi, S.; Zmeskal, J.

    The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. In 2007, KEK-PS E325 experiment reported about 3.4 % mass reduction of the ϕ meson in medium-heavy nuclei (Cu). This result is possibly one of the indications of the partial restoration of chiral symmetry in nuclei, however, unfortunately it is hard to make strong conclusions from the data. One of the ways to conclude the strength of the ϕ meson mass shift in nuclei will be by trying to produce only slowly moving ϕ mesons where the maximum nuclear matter effect can be probed. The observed mass reduction of the ϕ meson in the nucleus can be translated as the existence of an attractive force between ϕ meson and nucleus. Thus, one of the extreme conditions that can be achieved in the laboratory is indeed the formation of a ϕ-nucleus bound state, where the ϕ meson is "trapped" in the nucleus. The purpose of the experiment is to search for a ϕ-nucleus bound state and measure the binding energy of the system. We will demonstrate that a completely background-free missing-mass spectrum can be obtained efficiently by (bar{p}, φ) spectroscopy together with K + Λ tagging, using the primary reaction channel bar{p} p rightarrow φ φ. This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort.

  18. A search for ϕ meson nucleus bound state using antiproton annihilation on nucleus

    NASA Astrophysics Data System (ADS)

    Ohnishi, H.; Bühler, P.; Cargnelli, M.; Curceanu, C.; Guaraldo, C.; Hartmann, O.; Hicks, K.; Iwasaki, M.; Ishiwatari, T.; Kienle, P.; Marton, J.; Muto, R.; Naruki, M.; Niiyama, M.; Noumi, H.; Okada, S.; Vidal, A. Romero; Sakaguchi, A.; Sakuma, F.; Sawada, S.; Sirghi, D.; Sirghi, F.; Suzuki, K.; Tsukada, K.; Doce, O. Vazquez; Widmann, E.; Yokkaichi, S.; Zmeskal, J.

    2012-12-01

    The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. In 2007, KEK-PS E325 experiment reported about 3.4 % mass reduction of the ϕ meson in medium-heavy nuclei (Cu). This result is possibly one of the indications of the partial restoration of chiral symmetry in nuclei, however, unfortunately it is hard to make strong conclusions from the data. One of the ways to conclude the strength of the ϕ meson mass shift in nuclei will be by trying to produce only slowly moving ϕ mesons where the maximum nuclear matter effect can be probed. The observed mass reduction of the ϕ meson in the nucleus can be translated as the existence of an attractive force between ϕ meson and nucleus. Thus, one of the extreme conditions that can be achieved in the laboratory is indeed the formation of a ϕ-nucleus bound state, where the ϕ meson is "trapped" in the nucleus. The purpose of the experiment is to search for a ϕ-nucleus bound state and measure the binding energy of the system. We will demonstrate that a completely background-free missing-mass spectrum can be obtained efficiently by (bar{p}, φ) spectroscopy together with K + Λ tagging, using the primary reaction channel bar{p} p rightarrow φ φ. This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort.

  19. In vitro and in silico investigations of disc nucleus replacement

    PubMed Central

    Reitmaier, Sandra; Shirazi-Adl, Aboulfazl; Bashkuev, Maxim; Wilke, Hans-Joachim; Gloria, Antonio; Schmidt, Hendrik

    2012-01-01

    Currently, numerous hydrogels are under examination as potential nucleus replacements. The clinical success, however, depends on how well the mechanical function of the host structure is restored. This study aimed to evaluate the extent to and mechanisms by which surgery for nucleus replacements influence the mechanical behaviour of the disc. The effects of an annulus defect with and without nucleus replacement on disc height and nucleus pressure were measured using 24 ovine motion segments. The following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue repaired by suture and glue or plug. To identify the likely mechanisms observed in vitro, a finite-element model of a human disc (L4–L5) was employed. Both studies were subjected to physiological cycles of compression and recovery. A repaired annulus defect did not influence the disc behaviour in vitro, whereas additional nucleus removal and replacement substantially decreased disc stiffness and nucleus pressure. Model predictions demonstrated the substantial effects of reductions in replaced nucleus water content, bulk modulus and osmotic potential on disc height loss and pressure, similar to measurements. In these events, the compression load transfer in the disc markedly altered by substantially increasing the load on the annulus when compared with the nucleus. The success of hydrogels for nucleus replacements is not only dependent on the implant material itself but also on the restoration of the environment perturbed during surgery. The substantial effects on the disc response of disruptions owing to nucleus replacements can be simulated by reduced nucleus water content, elastic modulus and osmotic potential. PMID:22337630

  20. 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.

  1. In vitro and in silico investigations of disc nucleus replacement.

    PubMed

    Reitmaier, Sandra; Shirazi-Adl, Aboulfazl; Bashkuev, Maxim; Wilke, Hans-Joachim; Gloria, Antonio; Schmidt, Hendrik

    2012-08-07

    Currently, numerous hydrogels are under examination as potential nucleus replacements. The clinical success, however, depends on how well the mechanical function of the host structure is restored. This study aimed to evaluate the extent to and mechanisms by which surgery for nucleus replacements influence the mechanical behaviour of the disc. The effects of an annulus defect with and without nucleus replacement on disc height and nucleus pressure were measured using 24 ovine motion segments. The following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue repaired by suture and glue or plug. To identify the likely mechanisms observed in vitro, a finite-element model of a human disc (L4-L5) was employed. Both studies were subjected to physiological cycles of compression and recovery. A repaired annulus defect did not influence the disc behaviour in vitro, whereas additional nucleus removal and replacement substantially decreased disc stiffness and nucleus pressure. Model predictions demonstrated the substantial effects of reductions in replaced nucleus water content, bulk modulus and osmotic potential on disc height loss and pressure, similar to measurements. In these events, the compression load transfer in the disc markedly altered by substantially increasing the load on the annulus when compared with the nucleus. The success of hydrogels for nucleus replacements is not only dependent on the implant material itself but also on the restoration of the environment perturbed during surgery. The substantial effects on the disc response of disruptions owing to nucleus replacements can be simulated by reduced nucleus water content, elastic modulus and osmotic potential.

  2. The critical complex in nucleation is not the nucleus

    NASA Technical Reports Server (NTRS)

    Rasmussen, Don H.; Esen, Etop; Appleby, Mary R.

    1988-01-01

    A theory of nucleation is presented which combines features of classical nucleation. In this theory, the nucleus is a cluster of finite size with a sharp interface and spinodal decomposition, in which a fluctuation in density or composition generates the critical complex and nucleus. Thus, the nucleus is a product of nucleation. Schematic models for the classical and the proposed routes to nucleation are compared, focusing on the relation between pressure and volume in the models. In the proposed model, the critical complex, or critical state, is between the parent state and the nucleus.

  3. Nucleus properties of P/Schwassmann-Wachmann 1

    NASA Technical Reports Server (NTRS)

    Meech, Karen J.; Belton, Michael J. S.; Mueller, Beatrice E. A.; Dicksion, Matthew W.; Li, Heide R.

    1993-01-01

    Time series photometric measurements are presented of Comet P/Schwassmann-Wachmann 1 at a heliocentric distance of 5.886 AU when the comet possessed an extensive coma. The light curve shows a modulation caused by the rotation of the nucleus. The rotation period is considerably shorter than the 5 day period found by Whipple (1980), and we find substantial evidence that the nucleus may be in a complex spin state characterized by two periods 14.0 and 32.3 hr. Models of the rate at which the rotational light curve range decreases as a function of the amount of coma in the aperture have determined that the projected maximum to minimum axis ratio of the comet is 2.6 and that the product of the albedo times the rotationally averaged nucleus radius size is 9.54 +/- 0.3 sq km. Assuming a minimum geometric albedo of pR = 0.04, the maximum projected average nucleus radius is 15.44 +/-0.2 km, which is only 44 percent of the size estimated by Roemer (1966). However, using the albedo determined by Cruikshank & Brown (1983) of p = 0.13, the nucleus radius is only RN = 8.6 +/-0.l km. Because of the unknown nucleus orientation, these will be upper limits to the nucleus size. It appears that the nucleus of P/Schwassmann-Wachmann 1 is not the large nucleus that it has been believed to be for nearly 40 yr.

  4. 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.

  5. 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.

  6. 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.

  7. The nucleus of the Cygnus A galaxy

    NASA Astrophysics Data System (ADS)

    Vestergaard, M.; Barthel, P. D.

    1993-02-01

    New obtained high resolution optical images of the prototypical luminous radio galaxy Cygnus A (3C 405) indicate an inhomogeneous distribution of obscuring dust and, in combination with previous data, three types of radiation (stellar and blue featureless continuum as well as luminous line emission) in its central regions. The alleged double nucleus finds its origin in heavy obscuration coupled to excess line emission in the central regions of an otherwise normal giant elliptical galaxy. A strongly reddened nuclear component, coincident with the Cygnus A radio core, is found to emit faint but concentrated narrow line emission. All data appear consistent with identification of Cygnus A as a radio-loud quasar having its radio axis oriented at about 35 deg from the sky plane. The presumed dust torus obscuring the quasar continuum is inferred to be smaller than 800 parsec.

  8. In situ hybridization of suprachiasmatic nucleus slices.

    PubMed

    de la Iglesia, Horacio O

    2007-01-01

    The progress in the understanding of the molecular machinery of mammalian circadian clocks, in combination with the well-established role of the hypothalamic suprachiasmatic nucleus (SCN) as a master circadian clock, has provided an invaluable system for the study of the molecular basis of circadian rhythmicity. Using in situ hybridization (ISH) techniques that label specific clock-gene mRNAs within the SCN, researchers can now elucidate the core molecular oscillatory mechanisms underlying specific circadian physiological and behavioral phenotypes. In this chapter, two methods for ISH within the SCN are described. The first method is based on the fluorescent labeling of mRNA and is suitable for confocal microscopy analysis and double labeling techniques. The second method is based on the radioactive labeling of mRNA and is more sensitive and more adequate for the relative quantification of mRNA species.

  9. Analysis of Returned Comet Nucleus Samples

    NASA Astrophysics Data System (ADS)

    Chang, Sherwood

    1997-12-01

    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.

  10. 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. Copyright © 2012 Wiley Periodicals, Inc.

  11. Φ -meson-nucleus bound states

    NASA Astrophysics Data System (ADS)

    Cobos-Martínez, J. J.; Tsushima, K.; Krein, G.; Thomas, A. W.

    2017-09-01

    ϕ -meson-nucleus bound state energies and absorption widths are calculated for seven selected nuclei by solving the Klein-Gordon equation with complex optical potentials. Essential input for the calculations, namely the medium-modified K and K ¯ meson masses, as well as the density distributions in nuclei, are obtained from the quark-meson coupling model. The attractive potential for the ϕ meson in the nuclear medium originates from the in-medium enhanced K K ¯ loop in the ϕ -meson self-energy. The results suggest that the ϕ meson should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths.

  12. 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)

  13. 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

  14. Parabrachial nucleus involvement in multiple system atrophy☆

    PubMed Central

    Benarroch, E.E.; Schmeichel, A.M.; Low, P.A.; Parisi, J.E.

    2014-01-01

    Multiple system atrophy (MSA) is associated with respiratory dysfunction, including sleep apnea, respiratory dysrhythmia, and laryngeal stridor. Neurons of the parabrachial nucleus (PBN) control respiratory rhythmogenesis and airway resistance. Objectives The objective of this study is to determine whether there was involvement of putative respiratory regions of the PBN in MSA. Methods We examined the pons at autopsy in 10 cases with neuropathologically confirmed MSA and 8 age-matched controls. Sections obtained throughout the pons were processed for calcitonin-gene related peptide (CGRP) and Nissl staining to identify the lateral crescent of the lateral PBN (LPB) and the Kölliker-Fuse nucleus (K-F), which are involved in respiratory control. Cell counts were performed using stereology. Results There was loss of CGRP neurons in the PBN in MSA (total estimated cell counts for the external LPB cluster was 12,584 ± 1146 in controls and 5917 ± 389 in MSA, p < 0.0001); for the external medial PBN (MPB) cluster it was 15,081 ± 1758 in controls and 7842 ± 466 in MSA, p < 0.001. There was also neuronal loss in putative respiratory regions of the PBN, including the lateral crescent of the LPB (13,039 ± 1326 in controls and 4164 ± 872 in MSA, p < 0.0001); and K-F (5120 ± 495 in controls and 999 ± 308 in MSA, p < 0.0001). Conclusions There is involvement of both CGRP and putative respiratory cell groups in the PBN in MSA. Whereas the clinical implications of CGRP cell loss are still undetermined, involvement of the LPB and K-F may contribute to respiratory dysfunction in this disorder. PMID:23665165

  15. INORGANIC CATIONS IN THE CELL NUCLEUS

    PubMed Central

    Tres, Laura L.; Kierszenbaum, A. L.; Tandler, C. J.

    1972-01-01

    Earlier reports indicated the presence of significant amounts of inorganic salts in the nucleus. In the present study the possibility that this might be related to the transcription process was tested on seminiferous epithelium of the adult mouse, using potassium pyroantimonate as a fixative. The results indicated that a correlation exists between the inorganic cations comprising the pyroantimonate-precipitable fraction and the RNA synthetic activity. During meiotic prophase an accumulation of cation-antimonate precipitates occurs dispersed through the middle pachytene nuclei, the stage in which RNA synthesis reaches a maximum. At other stages (zygotene to diplotene), where RNA synthesis falls to a low level, that pattern is not seen; cation-antimonate deposits are restricted to a few masses in areas apparently free of chromatin. The condensed sex chromosomes, the heterochromatin of the "basal knobs," the axial elements, and the synaptonemal complexes are devoid of antimonate deposits during the meiotic prophase. The Sertoli cells, active in RNA synthesis in both nucleoplasm and nucleolus, show cation-antimonate deposits at these sites. In the nucleoplasm some "patches" of precipitates appear coincident with clusters of interchromatin granules; in the nucleolus the inorganic cations are mainly located in the fibrillar and/or amorphous areas, whereas relatively few are shown by the granular component. The condensed chromatin bodies associated with the nucleolus were always free of antimonate precipitates. It is suggested that the observed sites of inorganic cation accumulation within the nucleus may at least partially indicate the presence of RNA polymerases, the activity of which is dependent on divalent cations. PMID:4112542

  16. 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.

  17. Novel associated hydrogels for nucleus pulposus replacement.

    PubMed

    Thomas, Jonathan; Lowman, Anthony; Marcolongo, Michele

    2003-12-15

    Hydrogels of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blends may provide a material suitable for replacement of the nucleus pulposus of the intervertebral disc. This research examined the stability of these hydrogels under simulated physiological conditions. Polymer dissolution and stability were characterized over 120 days immersion, chemical surface analysis over 56 days immersion, and tensile mechanical behavior over 56 days immersion. Rubber elasticity theory was used by combining mechanical results with swelling data to calculate network characteristics such as the molecular weight between physical crosslinks and density of crosslinks. Properties were examined as a function of PVA/PVP composition as well as PVA molecular weight and PVP molecular weight. Results indicated that PVA/PVP blends prepared with moderate amounts of PVP (0.5-5%) resulted in a polymer network stabilized through interchain hydrogen bonding between hydroxyl groups on PVA chains and carbonyl groups on PVP chains. Most notably, a significant decrease in percentage of polymer mass loss was seen for blends prepared with 143K molecular weight PVA. Surface chemical analysis revealed that PVP unincorporated in the network structure suffered significant dissolution out of the polymer network and into solution. The molecular weight of PVA and PVP were shown to have a significant influence on the blends' network properties. Gels prepared with lower molecular weight PVA resulted in a more stable blend containing a higher density of crosslinks. However, blends prepared with a higher molecular weight PVA showed superior polymer network stability in dissolution studies. The blend that had the best combination of network stability under physiological conditions and a relatively tight, stable, and crosslinked network was prepared with 99% PVA (143K) and 1% PVP (40K). This material is proposed as an implant material for replacement of the degenerated nucleus pulposus.

  18. Projections to the rostral reticular thalamic nucleus in the rat.

    PubMed

    Cornwall, J; Cooper, J D; Phillipson, O T

    1990-01-01

    Afferent pathways to the rostral reticular thalamic nucleus (Rt) in the rat were studied using anterograde and retrograde lectin tracing techniques, with sensitive immunocytochemical methods. The analysis was carried out to further investigate previously described subregions of the reticular thalamic nucleus, which are related to subdivisions of the dorsal thalamus, in the paraventricular and midline nuclei and three segments of the mediodorsal thalamic nucleus. Cortical inputs to the rostral reticular nucleus were found from lamina VI of cingulate, orbital and infralimbic cortex. These projected with a clear topography to lateral, intermediate and medial reticular nucleus respectively. Thalamic inputs were found from lateral and central segments of the mediodorsal nucleus to the lateral and intermediate rostral reticular nucleus respectively and heavy paraventricular thalamic inputs were found to the medial reticular nucleus. In the basal forebrain, afferents were found from the vertical and horizontal limbs of the diagonal band, substantia innominata, ventral pallidum and medial globus pallidus. Brainstem projections were identified from ventrolateral periaqueductal grey and adjacent sites in the mesencephalic reticular formation, laterodorsal tegmental nucleus, pedunculopontine nucleus, medial pretectum and ventral tegmental area. The results suggest a general similarity in the organisation of some brainstem Rt afferents in rat and cat, but also show previously unsuspected inputs. Furthermore, there appear to be at least two functional subdivisions of rostral Rt which is reflected by their connections with cortex and thalamus. The studies also extend recent findings that the ventral striatum, via inputs from the paraventricular thalamic nucleus, is included in the circuitry of the rostral Rt, providing further evidence that basal ganglia may function in concert with Rt. Evidence is also outlined with regard to the possibility that rostral Rt plays a significant

  19. Pedunculopontine nucleus evoked potentials from subthalamic nucleus stimulation in Parkinson's disease.

    PubMed

    Neagu, Bogdan; Tsang, Eric; Mazzella, Filomena; Hamani, Clement; Moro, Elena; Hodaie, Mojgan; Lozano, Andres M; Chen, Robert

    2013-12-01

    The effects of subthalamic nucleus (STN) stimulation on the pedunculopontine nucleus area (PPNR) evoked activities were examined in two patients with Parkinson's disease. The patients had previously undergone bilateral STN deep brain stimulation (DBS) and subsequently received unilateral DBS electrodes in the PPNR. Evoked potentials were recorded from the local field potentials (LFP) from the PPNR with STN stimulation at different frequencies and bipolar contacts. Ipsilateral and contralateral short latency (<2ms) PPNR responses were evoked from left but not from right STN stimulation. In both patients, STN stimulation evoked contralateral PPNR responses at medium latencies between 41 and 45ms. Cortical evoked potentials to single pulse STN stimulation were observed at latencies between 18 and 27ms. These results demonstrate a functional connection between the STN and the PPNR. It likely involves direct projections between the STN and PPNR or polysynaptic pathways with thalamic or cortical relays.

  20. 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.

  1. Experimental evidence and the Landau-Zener promotion in nucleus-nucleus collisions

    SciTech Connect

    Cindro, N.; Freeman, R.M.; Haas, F.

    1986-04-01

    Recent data from C+O collisions are analyzed in terms of the Landau-Zener promotion in nuclei. Evidence for the presence of this mechanism in nuclear collisions is of considerable interest, since it provides a signature of single-particle orbitals in molecular-type potentials and, at the same time, paves the way to a microscopic understanding of the collision dynamics, in particular of the energy dissipation rate. The analyzed data are of two types: integrated cross sections and angular distributions of inelastically scattered particles. The first set of data shows structure qualitatively consistent with recent calculations of the Landau-Zener effect; for this set of data no other reasonable explanation is presently available. The second set of data, while consistent with the presence of the Landau-Zener promotion, is examined in terms of other possible explanations too. The combined data show evidence favoring the presence of the Landau-Zener promotion in nucleus-nucleus collisions.

  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. New quasibound states of the compound nucleus in α -particle capture by the nucleus

    NASA Astrophysics Data System (ADS)

    Maydanyuk, Sergei P.; Zhang, Peng-Ming; Zou, Li-Ping

    2017-07-01

    We generalize the theory of nuclear decay and capture of Gamow that is based on tunneling through the barrier and internal oscillations inside the nucleus. In our formalism an additional factor is obtained, which describes distribution of the wave function of the the α particle inside the nuclear region. We discover new most stable states (called quasibound states) of the compound nucleus (CN) formed during the capture of α particle by the nucleus. With a simple example, we explain why these states cannot appear in traditional calculations of the α capture cross sections based on monotonic penetrabilities of a barrier, but they appear in a complete description of the evolution of the CN. Our result is obtained by a complete description of the CN evolution, which has the advantages of (1) a clear picture of the formation of the CN and its disintegration, (2) a detailed quantum description of the CN, (3) tests of the calculated amplitudes based on quantum mechanics (not realized in other approaches), and (4) high accuracy of calculations (not achieved in other approaches). These peculiarities are shown with the capture reaction of α +44Ca . We predict quasibound energy levels and determine fusion probabilities for this reaction. The difference between our approach and theory of quasistationary states with complex energies applied for the α capture is also discussed. We show (1) that theory does not provide calculations for the cross section of α capture (according to modern models of the α capture), in contrast with our formalism, and (2) these two approaches describe different states of the α capture (for the same α -nucleus potential).

  4. Nucleus and nucleus-cytoskeleton connections in 3D cell migration.

    PubMed

    Liu, Lingling; Luo, Qing; Sun, Jinghui; Song, Guanbin

    2016-10-15

    Cell migration plays an important role in many physiological and pathological settings, ranging from embryonic development to cancer metastasis. Currently, accumulating data suggest that cells migrating in three-dimensional (3D) environments show well-defined differences compared to their well-established two-dimensional (2D) counterparts. During 3D migration, the cell body and nucleus must deform to allow cellular passage through the available spaces, and the deformability of the relatively rigid nucleus may constitute a limiting step. Here, we highlight the key evidence regarding the role of the nuclear mechanics in 3D migration, including the molecular components that govern the stiffness of the nucleus and review how the nuclear dynamics are connected to and controlled by cytoskeleton-based migration machinery. Intriguingly, nuclear movement must be coordinated with the cytoskeletal dynamics at the leading and trailing edges, which in turn impact the cytoplasmic dynamics that affect the migration efficiency. Thus, we suggest that alterations in the nuclear structure may facilitate cellular reorganizations that are necessary for efficient migration.

  5. Study of multiplicity correlations in nucleus-nucleus interactions at high energy

    NASA Astrophysics Data System (ADS)

    Mohery, M.; Sultan, E. M.; Baz, Shadiah S.

    2015-06-01

    In the present paper, some results on the correlations of the nucleus-nucleus interactions, at high energy, between different particle multiplicities are reported. The correlations between the multiplicities of the different charged particles emitted in the interactions of 22Ne and 28Si nuclei with emulsion at (4.1-4.5)A GeV/c have been studied. The correlations of the compound multiplicity nc, defined as the sum of both numbers of the shower particles ns and grey particles ng, have been investigated. The experimental data have been compared with the corresponding theoretical ones, calculated according to the modified cascade evaporation model (MCEM). An agreement has already been fairly obtained between the experimental values and the calculated ones. The dependence of the average compound multiplicity, on the numbers of shower, grey, black and heavy particles is obvious and the values of the slope have been found to be independent of the projectile nucleus. On the other hand, the variation of the average shower, grey, black and heavy particles is found to increase linearly with the compound particles. A strong correlation has been observed between the number of produced shower particles and the number of compound particles. Moreover, the value of the average compound multiplicity is found to increase with the increase of the projectile mass. Finally, an attempt has also been made to study the scaling of the compound multiplicity distribution showing that the compound multiplicity distribution is nearly consistent with the KNO scaling behavior.

  6. [Unilateral abolition of parkinsonian rigidity after subthalamic nucleus hemorrhage].

    PubMed

    Yamada, A; Takeuchi, H; Miki, H

    1992-08-01

    A 63-year-old man with parkinsonism suddenly developed a right hemiballism, and the CT showed a hematoma of the left subthalamic nucleus. After the ballistic movement had disappeared, muscular rigidity improved on the right. This case suggests that excessive output from the subthalamic nucleus to the internal segment of globus pallidus plays a critical role in the pathophysiology of parkinsonian rigidity.

  7. 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. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  8. 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…

  9. 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…

  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

    2014-11-07

    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. Afferent projections to the deep mesencephalic nucleus in the rat

    SciTech Connect

    Veazey, R.B.; Severin, C.M.

    1982-01-10

    Afferent projections to the deep mesencephalic nucleus (DMN) of the rat were demonstrated with axonal transport techniques. Potential sources for projections to the DMN were first identified by injecting the nucleus with HRP and examining the cervical spinal cord, brain stem, and cortex for retrogradely labeled neurons. Areas consistently labeled were then injected with a tritiated radioisotope, the tissue processed for autoradiography, and the DMN examined for anterograde labeling. Afferent projections to the medial and/or lateral parts of the DMN were found to originate from a number of spinal, bulbar, and cortical centers. Rostral brain centers projecting to both medial and lateral parts of the DMN include the ipsilateral motor and somatosensory cortex, the entopeduncular nucleus, and zona incerta. at the level of the midbrain, the ipsilateral substantia nigra and contralateral DMN likewise project to the DMN. Furthermore, the ipsilateral superior colliculus projects to the DMN, involving mainly the lateral part of the nucleus. Afferents from caudal centers include bilateral projections from the sensory nucleus of the trigeminal complex and the nucleus medulla oblongata centralis, as well as from the contralateral dentate nucleus. The projections from the trigeminal complex and nucleus medullae oblongatae centralis terminate in the intermediate and medial parts of the DMN, whereas projections from the contralateral dentate nucleus terminate mainly in its lateral part. In general, the afferent connections of the DMN arise from diverse areas of the brain. Although most of these projections distribute throughout the entire extent of the DMN, some of them project mainly to either medial or lateral parts of the nucleus, thus suggesting that the organization of the DMN is comparable, at least in part, to that of the reticular formation of the pons and medulla, a region in which hodological differences between medial and lateral subdivisions are known to exist.

  12. 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.

  13. Glycine immunoreactivity of multipolar neurons in the ventral cochlear nucleus which project to the dorsal cochlear nucleus.

    PubMed

    Doucet, J R; Ross, A T; Gillespie, M B; Ryugo, D K

    1999-06-14

    Certain distinct populations of neurons in the dorsal cochlear nucleus are inhibited by a neural source that is responsive to a wide range of acoustic frequencies. In this study, we examined the glycine immunoreactivity of two types of ventral cochlear nucleus neurons (planar and radiate) in the rat which project to the dorsal cochlear nucleus (DCN) and thus, might be responsible for this inhibition. Previously, we proposed that planar neurons provided a tonotopic and narrowly tuned input to the DCN, whereas radiate neurons provided a broadly tuned input and thus, were strong candidates as the source of broadband inhibition (Doucet and Ryugo [1997] J. Comp. Neurol. 385:245-264). We tested this idea by combining retrograde labeling and glycine immunohistochemical protocols. Planar and radiate neurons were first retrogradely labeled by injecting biotinylated dextran amine into a restricted region of the dorsal cochlear nucleus. The labeled cells were visualized using streptavidin conjugated to indocarbocyanine (Cy3), a fluorescent marker. Sections that contained planar or radiate neurons were then processed for glycine immunocytochemistry using diaminobenzidine as the chromogen. Immunostaining of planar neurons was light, comparable to that of excitatory neurons (pyramidal neurons in the DCN), whereas immunostaining of radiate neurons was dark, comparable to that of glycinergic neurons (cartwheel cells in the dorsal cochlear nucleus and principal cells in the medial nucleus of the trapezoid body). These results are consistent with the hypothesis that radiate neurons in the ventral cochlear nucleus subserve the wideband inhibition observed in the dorsal cochlear nucleus.

  14. 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

  15. Functional network inference of the suprachiasmatic nucleus

    SciTech Connect

    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.

    2016-04-04

    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.

  16. Functional network inference of the suprachiasmatic nucleus

    PubMed Central

    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.

    2016-01-01

    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

  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. 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

  19. Development of the human dentate nucleus.

    PubMed

    Mihajlovic, P; Zecevic, N

    1986-01-01

    The developing human dentate nucleus (DN) was studied in a series of specimens of various pre- and postnatal ages ranging from 8 gestational weeks (gw) to 10 years, in Golgi-impregnated and Nissl-stained material. The DN emerges from the cerebellar white matter at around 16 gestational weeks (gw) as a thick band of cells (600-700 micron in width) that gradually attenuates to a final width of 150-250 micron as it undergoes extensive infolding beginning around 24 gw. The highly convoluted configuration of the adult DN is recognizable by 35 gw. Around 16 gw, two basic classes of DN neurons can be identified. Differentiation of these neurons is especially intensive during the mid-gestational period (20-25 gw). At this time the size of cell bodies increases, dendrites branch profusely and acquire spines. A second, slower phase of maturation consisting of addition of secondary and tertiary branches, continues into the postnatal period. At all prenatal ages examined, dentate neurons are morphologically more mature than the Purkinje cells in the overlying cortex. DN neurons of premature infants did not show cytomorphological differences when compared with babies born at term.

  20. 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.

  1. Restoring Segmental Biomechanics Through Nucleus Augmentation: An In Vitro Study.

    PubMed

    Pelletier, Matthew H; Cohen, Charles S; Ducheyne, Paul; Walsh, William R

    2016-12-01

    In vitro biomechanical laboratory study. The purpose of this study is to evaluate a mechanical treatment to create a degenerative motion segment and the ability of nucleus augmentation to restore biomechanics. In cases with an intact annulus fibrosus, the replacement or augmentation of the nucleus pulposus alone may provide a less invasive option to restore normal biomechanics and disk height when compared with spinal fusion or total disk replacement. Laboratory testing allows these changes to be fully characterized. However, without preexisting pathology, nucleus augmentation therapies are difficult to evaluate in vitro. The present study evaluated pure moment bending and compressive biomechanics in 3 states (n=6): (1) intact, (2) after creep loading and nucleus disruption to induce degenerative biomechanical changes, and (3) after nucleus augmentation through an injectable polymer (DiscCell). Neutral zone and ROM were increased in all modes of bending after the degenerative treatment. The most sensitive mode of bending was lateral bending, with intact ROM (20.0±2.9 degrees) increased to 22.3±2.6 degrees after degenerative treatment and reduced to 18.4±1.6 degrees after injection of the polymer. All bending ROM and NZ changes induced by the degenerative treatment were reversed by nucleus augmentation. This material was shown to be effective at altering motion segment biomechanics and restoring disk height during time zero tests. This technique may provide a model to examine the time zero performance of a nucleus augmentation device/material.

  2. Did Struve observe the nucleus of Halley's comet in 1835?

    NASA Astrophysics Data System (ADS)

    Wittmann, Axel D.

    During its apparition in 1835 Halley's comet reached its minimum distance from the earth (0.187 au) on 13 October in the constellation of Ursa Major. Telescopic visual observations were made, e.g., by F.W. Bessel at Königsberg and by F.G.W. Struve at Dorpat (Tartu). In particular a drawing made by Struve on 8 October of what he calls the `nucleus' and describes as a small, slightly yellowish glowing piece of coal of elongated shape bears such a striking resemblance to the images of Halley's nucleus obtained in 1986 by the Giotto spacecraft that it merits further examination: Could Struve, who had been using a 24.4 cm refractor at 254-fold magnification, possibly have observed the real nucleus? Closer examination shows that neither Struve's maximum possible resolution (0.13 arc seconds or 23 km at the comet), nor his measured size of the nucleus (160 x 400 km), nor his verbal description of the nucleus (as a bright object) support this idea: It rather seems that the term `nucleus' was used at the time for the brightest, innermost part of the coma. It is concluded that, nevertheless, Struve quite correctly envisaged the structure of the innermost coma, and to a considerable degree of accuracy anticipated the correct shape and structure of the nucleus (elongated, 1:2) and its localized sources of outstreaming gas.

  3. Development of the human dorsal nucleus of the vagus.

    PubMed

    Cheng, Gang; Zhu, Hua; Zhou, Xiangtian; Qu, Jia; Ashwell, K W S; Paxinos, G

    2008-01-01

    The dorsal nucleus of the vagus nerve plays an integral part in the control of visceral function. The aim of the present study was to correlate structural and chemical changes in the developing nucleus with available data concerning functional maturation of human viscera and reflexes. The fetal development (ages 9 to 26 weeks) of the human dorsal nucleus of the vagus nerve has been examined with the aid of Nissl staining and immunocytochemistry for calbindin and tyrosine hydroxylase. By 13 weeks, the dorsal vagal nucleus emerges as a distinct structure with at least two subnuclei visible in Nissl stained preparations. By 15 weeks, three subnuclei (dorsal intermediate, centrointermediate and ventrointermediate) were clearly discernible at the open medulla level with caudal and caudointermediate subnuclei visible at the level of the area postrema. All subnuclei known to exist in the adult were visible by 21 weeks and cytoarchitectonic differentiation of the nucleus was largely completed by 25 weeks. The adult distribution pattern of calbindin and tyrosine hydroxylase immunoreactive neurons was also largely completed by 21 weeks, although morphological differentiation of labeled neurons continued until the last age examined (26 weeks). The structural development of the dorsal nucleus of the vagus nerve appears to occur in parallel with functional maturation of the cardiovascular and gastric movements, which the nucleus controls.

  4. Inputs to the ventrolateral bed nucleus of the stria terminalis

    PubMed Central

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

    2009-01-01

    The ventrolateral bed nucleus of the stria terminalis (BSTvl) receives direct input from two specific subpopulations of neurons in the nucleus tractus solitarius (NTS). It is heavily innervated by aldosterone-sensitive NTS neurons, which are selectively activated by sodium depletion, and by the A2 noradrenergic neurons, which are activated by visceral, immune- and stress-related stimuli. Here, we used a retrograde neuronal tracer to identify other brain sites that innervate the BSTvl. Five general brain regions contained retrogradely labeled neurons: cerebral cortex (infralimbic and insular regions), rostral forebrain structures (subfornical organ, organum vasculosum of the lamina terminalis, taenia tecta, nucleus accumbens, lateral septum, endopiriform nucleus, dorsal BST, substantia innominata, and most prominently the amygdala – primarily its basomedial and central subnuclei), thalamus (central medial, intermediodorsal, reuniens, and most prominently the paraventricular thalamic nucleus), hypothalamus (medial preoptic area, perifornical, arcuate, dorsomedial, parasubthalamic, and posterior hypothalamic nuclei), and brainstem (periaqueductal gray matter, dorsal and central superior raphe nuclei, parabrachial nucleus, pre-locus coeruleus region, NTS, and A1 noradrenergic neurons in the caudal ventrolateral medulla). In the arcuate hypothalamic nucleus, some retrogradely-labeled neurons contained either agouti-related peptide or cocaine-amphetamine regulated transcript. Of the numerous retrogradely labeled neurons in the perifornical hypothalamic area, few contained melanin concentrating hormone or orexin. In the brainstem, many retrogradely labeled neurons were either serotoninergic or catecholaminergic. In summary, the BSTvl receives inputs from a variety of brain sites implicated in hunger, salt and water intake, stress, arousal, and reward. PMID:18853414

  5. 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.

  6. 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.

  7. Particle-number conservation in odd mass proton-rich nuclei in the isovector pairing case

    NASA Astrophysics Data System (ADS)

    Fellah, M.; Allal, N. H.; Oudih, M. R.

    2015-06-01

    An expression of a wave function which describes odd-even systems in the isovector pairing case is proposed within the BCS approach. It is shown that it correctly generalizes the one used in the pairing between like-particles case. It is then projected on the good proton and neutron numbers using the Sharp-BCS (SBCS) method. The expressions of the expectation values of the particle-number operator and its square, as well as the energy, are deduced in both approaches. The formalism is applied to study the isovector pairing effect and the number projection one on the ground state energy of odd mass N ≈ Z nuclei using the single-particle energies of a deformed Woods-Saxon mean-field. It is shown that both effects on energy do not exceed 2%, however, the absolute deviations may reach several MeV. Moreover, the np pairing effect rapidly diminishes as a function of (N - Z). The deformation effect is also studied. It is shown that the np pairing effect, either before or after the projection, as well as the projection effect, when including or not the isovector pairing, depends upon the deformation. However, it seems that the predicted ground state deformation will remain the same in the four approaches.

  8. Electromagnetic Moments of Proton-Rich {sup 28}P and Decomposition of Its Spin

    SciTech Connect

    Matsuta, K.; Mihara, M.; Nishimura, D.; Fukuda, M.; Matsumiya, R.; Komurasaki, J.; Ishikawa, D.; Ogura, M.; Akai, H.; Zhu, Shengyun; Zhou, Dongmei; Zheng, Yongnan; Yuan, Daqing; Zuo, Yi; Fan, Ping; Zhang, Xizhen; Suzuki, T.; Nagatomo, T.; Izumikawa, T.; Ohtsubo, T.

    2010-05-12

    The magnetic moment of {sup 28}P(Ipi = 3{sup +}, T{sub 1/2} = 270.3 ms) has been measured precisely by means of beta-NMR technique. The obtained magnetic moment is |mu({sup 28}P)| = 0.3115 (34) mu{sub N}. Combined with the magnetic moment of its mirror partner {sup 28}Al, the nuclear spin I = 3 is decomposed into its 4 components. The measurement of the Q moment has also been tried. From the preliminary NQR spectrum, it was found that the quadrupole coupling constant eqQ/h may be slightly larger than the prediction, which may show enhancement of the Q moment.

  9. Beta Decay Studies of Proton Rich Nuclei, an Important Ingredient for rp-Process Calculations

    NASA Astrophysics Data System (ADS)

    Rubio, B.; Kucuk, L.; Orrigo, S. E. A.; Fujita, Y.; Gelletly, W.; Blank, B.; Adachi, T.; Aguilera, P.; Agramunt, J.; Algora, A.; Ascher, P.; Bilgier, B.; Cáceres, L.; Cakirli, R. B.; de France, G.; de Oliveira Santos, F.; Fujita, H.; Ganioğlu, E.; Gerbaux, M.; Giovinazzo, J.; Grévy, S.; Kamalou, O.; Kozer, H. C.; Kurtukian-Nieto, T.; Marqués, M.; Molina, F.; Nishimura, D.; Oikawa, H.; Oktem, Y.; Perrot, L.; Popescu, L.; Raabe, R.; Rogers, A. M.; Srivastava, P. C.; Susoy, G.; Stodel, C.; Suzuki, T.; Tamii, A.; Thomas, J. C.

    We have performed a series of beta-decay experiments at fragmentation facilities on Tz = -1/2, Tz = -1, and Tz = -2 nuclei. Most of these nuclei lie on the rp-process path and therefore some of the quantities we have measured such as T1/2 values are important ingredients in performing reaction flow calculations for light curve estimates and testing astrophysical models of X-ray bursters. At this conference we have presented the results of measurements of T1/2 values for 25 nuclei and compared with previous values.

  10. Microscopic calculation for α and heavier cluster emissions from proton rich Ba and Ce isotopes

    NASA Astrophysics Data System (ADS)

    Florescu, A.; Insolia, A.

    1995-08-01

    We present a completely microscopic approach for obtaining the preformation factors and the decay widths of α, 12Ca, and 16O cluster decays. We start from realistic single particle Woods-Saxon wave functions and include a large space BCS-type configuration mixing. A pairing interaction acting among valence particles, placed above a double magic core, was considered. The penetrability is evaluated within the WKB approximation. The model predictions are also checked for some well-known α and 14C decays from even-even nuclei.

  11. 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.

  12. 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.

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

    DOE PAGES

    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.

  14. Nucleus of Comet IRAS-Araki-Alcock (1983 VII)

    NASA Technical Reports Server (NTRS)

    Sekanina, Z.

    1988-01-01

    Optical, radar, infrared, UV, and microwave-continuum observations of Comet IRAS-Araki-Alcok were obtained in May 1983, the week of the comet's close approach to earth. The comet has a nucleus dimension and a rotation period which are similar to those of Comet Halley, but a different morphological signature (a persisting sunward fan-shaped coma). Time variations are noted in the projected nucleus cross section. Results suggest significant limb-darkening effects in the relevant domains of radio waves, and that the comet's interior must be extremely cold. It is found that the thermal-infrared fluxes from the inner coma of the comet are dominated by the nucleus.

  15. 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.

  16. 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.

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

    PubMed

    Takahashi, T T; Konishi, M

    1988-08-08

    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.

  18. 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

  19. The Acasta Gneiss - a Hadean cratonic nucleus

    NASA Astrophysics Data System (ADS)

    Sprung, P.; Scherer, E. E.; Maltese, A.; Bast, R.; Bleeker, W.; Mezger, K.

    2016-12-01

    The known terrestrial rock record lacks undisputed, chemically intact Hadean crust. Direct evidence from this eon has been restricted to zircon grains within younger rocks [1]. The Acasta Gneiss Complex (AGC; NT, CA) has yielded zircon with Hadean domains [e.g., 2,3], but the time at which AGC rocks became closed chemical systems is unclear [4,5]. Determining this `time of last disturbance' (tld) would provide a minimum protolith age, and is crucial for using radiogenic isotope compositions of bulk rocks to trace crust-mantle evolution. Recent studies mostly focused on the `low-strain' eastern AGC [e.g., 6, 7], which records an evolving, early-mid Archean cratonic nucleus [7]. We also studied the `high-strain' banded gneiss in the western AGC, which hosts >4 Ga zircon domains [2,3], too. Our focusing lay on adjoining, lithologically distinct bands [8] of two distinct chemical groups: A) Mafic, chondrite-normalized LaN/YbN ≦20, slightly HFSE- depleted, and B) TTG-like, LaN/YbN up to 145, markedly HFSE-depleted. Six adjacent bands yield a well-defined 4 Ga Sm-Nd isochron with a ɛNd4Ga of +2 and ɛHf4Ga values from +1 to +6. Within-band Sm-Nd and Lu-Hf systematics imply younger mineral re-equilibration [9]. We interpret the 4 Ga Sm-Nd isochron to date the physical juxtaposition of bands in the gneiss unit and to define tld among bands for elements less mobile and diffusive than Sm and Nd. Contrasting Sm-Nd results from the same unit [10] likely are due to sampling at too fine a scale. Digestion of metamict pre-tld zircon likely caused the scatter in Lu-Hf. Both decay systems hint at the existence of a possibly local, strongly depleted Hadean mantle domain. The TTG-like bands are 0.4 Gyr older than similar rocks in the `low-strain' eastern AGC [7]. The AGC was thus an evolved cratonic nucleus already at 4 Ga, possibly with a depleted lithospheric keel. [1] Cavosie et al. (2004) Prec. Res. 135, 251-279 [2] Bowring & Williams (1999) CMP 134, 3-16 [3] Iizuka et al

  20. Nucleus Accumbens Invulnerability to Methamphetamine Neurotoxicity

    PubMed Central

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

    2016-01-01

    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. PMID:23382149

  1. 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.

  2. Observation of the antimatter helium-4 nucleus

    SciTech Connect

    Agakishiev, H.; Tang, A.; et al.

    2011-04-24

    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 ({sup 4}He), also known as the anti-{alpha} ({alpha}), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the {alpha}-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 {sup 4}He, the heaviest observed antinucleus to date. In total, 18 {sup 4}He counts were detected at the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) in 10{sup 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 {sup 4}He in cosmic radiation.

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

    PubMed

    Vertes, Robert P

    2015-01-01

    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. © 2015 Elsevier B.V. All rights reserved.

  5. 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

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Cap, T.; Siwek-Wilczyńska, K.; Wilczyński, J.

    2011-05-01

    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 σcap(l), the fusion probability Pfus(l), and the survival probability Psurv(l). The fusion hindrance factor, the inverse of Pfus(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 Pfus(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.

  8. 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

  9. Suprachiasmatic Nucleus Interaction with the Arcuate Nucleus; Essential for Organizing Physiological Rhythms

    PubMed Central

    Guzmán-Ruiz, Mara

    2017-01-01

    Abstract The suprachiasmatic nucleus (SCN) is generally considered the master clock, independently driving all circadian rhythms. We recently demonstrated the SCN receives metabolic and cardiovascular feedback adeptly altering its neuronal activity. In the present study, we show that microcuts effectively removing SCN-arcuate nucleus (ARC) interconnectivity in Wistar rats result in a loss of rhythmicity in locomotor activity, corticosterone levels, and body temperature in constant dark (DD) conditions. Elimination of these reciprocal connections did not affect SCN clock gene rhythmicity but did cause the ARC to desynchronize. Moreover, unilateral SCN lesions with contralateral retrochiasmatic microcuts resulted in identical arrhythmicity, proving that for the expression of physiological rhythms this reciprocal SCN-ARC interaction is essential. The unaltered SCN c-Fos expression following glucose administration in disconnected animals as compared to a significant decrease in controls demonstrates the importance of the ARC as metabolic modulator of SCN neuronal activity. Together, these results indicate that the SCN is more than an autonomous clock, and forms an essential component of a larger network controlling homeostasis. The present novel findings illustrate how an imbalance between SCN and ARC communication through circadian disruption could be involved in the etiology of metabolic disorders. PMID:28374011

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

    PubMed

    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

    2011-04-05

    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.

  11. Constraining in-medium nucleon-nucleon interactions via nucleus-nucleus reactions

    NASA Astrophysics Data System (ADS)

    Sammarruca, Francesca; White, Larz

    2010-11-01

    The nuclear equation of state is a broadly useful tool. Besides being the main input of stellar structure calculations, it allows a direct connection to the physics of nuclei. For instance, an energy functional (such as a mass formula), together with the energy/particle in nuclear matter, can be used to predict nuclear energies and radii [1]. The single-particle properties are also a key point to link infinite nuclear matter and actual nuclei. The parameters of the single-particle potential, in particular the effective mass, enter the calculations of, for instance, in-medium effective cross sections. From the well-known Glauber reaction theory, the total nucleus-nucleus reaction cross section is expressed in terms of the nuclear transparency, which, in turn, depends on the overlap of the nuclear density distributions and the elementary nucleon-nucleon (NN) cross sections. We explore the sensitivity of the reaction calculation to medium modifications of the NN cross sections to estimate the likelihood of constraining the latter through nuclear reactions. Ultimately, we wish to incorporate isospin asymmetry in the reaction model, having in mind connections with rare isotopes. [1] F. Sammarruca, arXiv:1002.00146 [nucl-th]; International Journal of Modern Physics, in press.

  12. 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.

  13. Quantitative analysis of the fusion cross sections using different microscopic nucleus-nucleus interactions

    NASA Astrophysics Data System (ADS)

    Adel, A.; Alharbi, T.

    2017-01-01

    The fusion cross sections for reactions involving medium and heavy nucleus-nucleus systems are investigated near and above the Coulomb barrier using the one-dimensional barrier penetration model. The microscopic nuclear interaction potential is computed by four methods, namely: the double-folding model based on a realistic density-dependent M3Y NN interaction with a finite-range exchange part, the Skyrme energy density functional in the semiclassical extended Thomas-Fermi approximation, the generalized Proximity potential, and the Akyüz-Winther interaction. The comparison between the calculated and the measured values of the fusion excitation functions indicates that the calculations of the DFM give quite satisfactory agreement with the experimental data, being much better than the other methods. New parameterized forms for the fusion barrier heights and positions are presented. Furthermore, the effects of deformation and orientation degrees of freedom on the distribution of the Coulomb barrier characteristics as well as the fusion cross sections are studied for the reactions 16 O + 70 Ge and 28 Si + 100 Mo. The calculated values of the total fusion cross sections are compared with coupled channel calculations using the code CCFULL and compared with the experimental data. Our results reveal that the inclusion of deformations and orientation degrees of freedom improves the comparison with the experimental data.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 3D Protein Dynamics in the Cell Nucleus.

    PubMed

    Singh, Anand P; Galland, Rémi; Finch-Edmondson, Megan L; Grenci, Gianluca; Sibarita, Jean-Baptiste; Studer, Vincent; Viasnoff, Virgile; Saunders, Timothy E

    2017-01-10

    The three-dimensional (3D) architecture of the cell nucleus plays an important role in protein dynamics and in regulating gene expression. However, protein dynamics within the 3D nucleus are poorly understood. Here, we present, to our knowledge, a novel combination of 1) single-objective based light-sheet microscopy, 2) photoconvertible proteins, and 3) fluorescence correlation microscopy, to quantitatively measure 3D protein dynamics in the nucleus. We are able to acquire >3400 autocorrelation functions at multiple spatial positions within a nucleus, without significant photobleaching, allowing us to make reliable estimates of diffusion dynamics. Using this tool, we demonstrate spatial heterogeneity in Polymerase II dynamics in live U2OS cells. Further, we provide detailed measurements of human-Yes-associated protein diffusion dynamics in a human gastric cancer epithelial cell line.

  1. Radiometric observations of the nucleus of Comet Halley

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Images obtained by the Halley multicolor camera (HMC) were used to determine the surface brightness of the nucleus. Radiometric values of jet-free areas of the surface are presented and a range of possible surface brightness values are derived. These direct measures are compared with brightnesses derived from the size of the nucleus, as determined from HMC images, and ground-based observations obtained before the onset of coma activity.

  2. The Galactic nucleus: A unique region in the Galactic ecosystem

    NASA Technical Reports Server (NTRS)

    Genzel, Reinhard; Poglitsch, Albrecht

    1995-01-01

    The nucleus is a unique region in the Galactic ecosystem. It is also superb laboratory of modern astrophysics where astronomers can study, at unprecedented spatial resolution and across the entire electromagnetic spectrum, physical processes that may also happen at the cores of other galaxies. Infrared observations from the Kuiper Airborne Observatory have made important contributions to unraveling the mysteries of the Galactic nucleus and this review highlights some of these measurements, as well as recent results regarding the central parsec.

  3. 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.

  4. 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

  5. Colour, albedo and nucleus size of Halley's comet

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Tholen, D. J.; Hartmann, W. K.

    1985-01-01

    Photometry of Halley's comet in the B, J, V, and K broadband filters during a time when the coma was very weak and presumed to contribute negligibly to the broadband photometry is reported. The V-J and J-K colors suggest that the color of the nucleus of Halley's comet is similar to that of the D-type asteroids, which in turn suggests that the surface of the nucleus has an albedo less than 0.1.

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

    PubMed

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

    2014-10-09

    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. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Glucokinase activity in the arcuate nucleus regulates glucose intake

    PubMed Central

    Hussain, Syed; Richardson, Errol; Ma, Yue; Holton, Christopher; De Backer, Ivan; Buckley, Niki; Dhillo, Waljit; Bewick, Gavin; Zhang, Shuai; Carling, David; Bloom, Steve; Gardiner, James

    2014-01-01

    The brain relies on a constant supply of glucose, its primary fuel, for optimal function. A taste-independent mechanism within the CNS that promotes glucose delivery to the brain has been postulated to maintain glucose homeostasis; however, evidence for such a mechanism is lacking. Here, we determined that glucokinase activity within the hypothalamic arcuate nucleus is involved in regulation of dietary glucose intake. In fasted rats, glucokinase activity was specifically increased in the arcuate nucleus but not other regions of the hypothalamus. Moreover, pharmacologic and genetic activation of glucokinase in the arcuate nucleus of rodent models increased glucose ingestion, while decreased arcuate nucleus glucokinase activity reduced glucose intake. Pharmacologic targeting of potential downstream glucokinase effectors revealed that ATP-sensitive potassium channel and P/Q calcium channel activity are required for glucokinase-mediated glucose intake. Additionally, altered glucokinase activity affected release of the orexigenic neurotransmitter neuropeptide Y in response to glucose. Together, our results suggest that glucokinase activity in the arcuate nucleus specifically regulates glucose intake and that appetite for glucose is an important driver of overall food intake. Arcuate nucleus glucokinase activation may represent a CNS mechanism that underlies the oft-described phenomena of the “sweet tooth” and carbohydrate craving. PMID:25485685

  8. 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

  9. International Halley Watch: Discipline specialists for near-nucleus studies

    NASA Technical Reports Server (NTRS)

    Larson, S.; Sekanina, Z.; Rahe, J.

    1986-01-01

    The purpose of the Near-Nucleus Studies Net is to study the processes taking place in the near-nucleus environment as they relate to the nature of nucleus. This is accomplisghed by measuring the spatial and temporal distribution of dust, gases and ions in the coma on high resolution images taken from many observatories around the world. By modeling the motions of discrete dust features in Comet Halley, it is often possible to determine the locations of the emission sources on the surface and learn about the nucleus structure. In addition to the general goals shared by all IHW nets, the scientific goals of the net has been to determine (1)the gross surface structure of the nucleus, (2)the nucleus spin vector, (3)the distribution and evolution of jet sources and (4)the interrelationships between the gas, dust and ion components of the coma. An additional Comet Giacobini-Zinner watch was carried out by the NNSN in support of the NASA International Cometary Explorer flyby.

  10. 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

  11. Cytoarchitecture and saccular innervation of nucleus y in the mouse.

    PubMed

    Frederickson, C J; Trune, D R

    1986-10-15

    The cytoarchitecture and saccular innervation of the mouse nucleus y were investigated by using Golgi, Nissl, and myelin stains and anterograde axonal transport of horseradish peroxidase. Nucleus y was found to be a compact group of cells in a small fiber-free region dorsal to the restiform body. Qualitative and morphometric analyses showed that most (75%) of the nucleus y neurons could not be reliably subdivided into morphologic subgroups, but varied continuously in soma size (15-25 microns), shape (fusiform to stellate), and number of dendrites (two to four), and had sparsely branched dendrites with an average of 3 to 4 spines per 10 microns of length. Three groups of cells that were identified morphometrically accounted for 10% (type I: large stellate cells), 9% (type II: long-dendrite cells), and 6% (type III: elongated soma cells) of the y neurons. Vestibular nerve axons transporting horseradish peroxidase after injury at their origin in the saccular neuroepithelium were found to form a dense terminal meshwork that was virtually co-extensive with the cytoarchitectonic boundaries of nucleus y. Nucleus y was distinguished from the overlying infracerebellar nucleus on the basis of anatomical, cytoarchitectural, and hodological features.

  12. 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

  13. 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.

  14. Plastid-Nucleus Distance Alters the Behavior of Stromules

    PubMed Central

    Erickson, Jessica L.; Kantek, Matthias; Schattat, Martin H.

    2017-01-01

    Plastids send “retrograde” signals to the nucleus to deliver information regarding their physiological status. One open question concerning this signal transfer is how the signal bridges the cytoplasm. Based on individual reports of plastid derived tubular membrane extensions connecting to nuclei, these so-called stromules have been suggested to function as communication routes between plastids and nuclei in response to biotic stress. However, based on the data currently available it is unclear whether interactions between stromules and nuclei are truly intentional or observed as a result of an inflated stromule frequency throughout the cell, and are thus a random event. The source of this uncertainty stems from missing information regarding the relative distribution of all plastids and stromules within a given cell. A comprehensive analysis of the upper epidermis of Arabidopsis thaliana rosette leaves was performed via a combination of still images and time-lapse movies of stromule formation in the context of the whole cell. This analysis could definitively confirm that stromule formation is not evenly distributed. Stromules are significantly more frequent within 8 μm of the nucleus, and approximately 90% of said stromules formed facing the nucleus. Time-lapse movies revealed that this enrichment of stromules is achieved via a 10-fold higher frequency of stromule initiation events within this 8 μm zone compared to the cell periphery. Following the movement of plastids and nuclei it became evident that movement and formation of stromules is correlated to nucleus movement. Observations suggest that stromules “connecting” to the nucleus are not necessarily the result of plastids sensing the nucleus and reaching out toward it, but are rather pulled out of the surface of nucleus associated plastids during opposing movement of these two organelles. This finding does not exclude the possibility that stromules could be transferring signals to the nucleus

  15. The interfascicular trigeminal nucleus: a precerebellar nucleus in the mouse defined by retrograde neuronal tracing and genetic fate mapping.

    PubMed

    Fu, Yuhong; Tvrdik, Petr; Makki, Nadja; Machold, Robert; Paxinos, George; Watson, Charles

    2013-02-15

    We have found a previously unreported precerebellar nucleus located among the emerging fibers of the motor root of the trigeminal nerve in the mouse, which we have called the interfascicular trigeminal nucleus (IF5). This nucleus had previously been named the tensor tympani part of the motor trigeminal nucleus (5TT) in rodent brain atlases, because it was thought to be a subset of small motor neurons of the motor trigeminal nucleus innervating the tensor tympani muscle. However, following injection of retrograde tracer in the cerebellum, the labeled neurons in IF5 were found to be choline acetyltransferase (ChAT) negative, indicating that they are not motor neurons. The cells of IF5 are strongly labeled in mice from Wnt1Cre and Atoh1 CreER lineage fate mapping, in common with the major precerebellar nuclei that arise from the rhombic lip and that issue mossy fibers. Analysis of sections from mouse Hoxa3, Hoxb1, and Egr2 Cre labeled lineages shows that the neurons of IF5 arise from rhombomeres caudal to rhombomere 4, most likely from rhombomeres 6-8. We conclude that IF5 is a significant precerebellar nucleus in the mouse that shares developmental gene expression characteristics with mossy fiber precerebellar nuclei that arise from the caudal rhombic lip.

  16. The turtle thalamic anterior entopeduncular nucleus shares connectional and neurochemical characteristics with the mammalian thalamic reticular nucleus.

    PubMed

    Kenigfest, Natalia; Belekhova, Margarita; Repérant, Jacques; Rio, Jean Paul; Ward, Roger; Vesselkin, Nikolai

    2005-10-01

    Neurochemical and key connectional characteristics of the anterior entopeduncular nucleus (Enta) of the turtle (Testudo horsfieldi) were studied by axonal tracing techniques and immunohistochemistry of parvalbumin, gamma-aminobutyric acid (GABA) and glutamic acid decarboxylase (GAD). We showed that the Enta, which is located within the dorsal peduncle of the lateral forebrain bundle (Pedd), has roughly topographically organized reciprocal connections with the dorsal thalamic visual nuclei, the nucleus rotundus (Rot) and dorsal lateral geniculate nucleus (GLd). The Enta receives projections from visual telencephalic areas, the anterior dorsal ventricular ridge and dorsolateral cortex/pallial thickening. Most Enta neurons contained GABA and parvalbumin, and some of them were retrogradely labeled when the tracer was injected into the visual dorsal thalamic nuclei. Further experiments using double immunofluorescence revealed colocalization of GAD and parvalbumin in the vast majority of Enta neurons, and many of these cells showed retrograde labeling with Fluoro-gold injected into the Rot and/or GLd. According to these data, the Enta may be considered as a structural substrate for recurrent inhibition of the visual thalamic nuclei. Based on morphological and neurochemical similarity of the turtle Enta, caiman Pedd nucleus, the superior reticular nucleus in birds, and the thalamic reticular nucleus in mammals, we suggest that these structures represent a characteristic component which is common to the thalamic organization in amniotes.

  17. Some morphological features of a visual thalamic nucleus in a reptile: observations on nucleus rotundus in Caiman crocodilus.

    PubMed

    Pritz, M B

    1997-01-01

    The morphology of nucleus rotundus, a visual thalamic nucleus, was investigated in one species of reptiles. Caiman crocodilus, using Nisst stained material in transverse, sagittal, and horizontal planes. The topographical location of nucleus rotundus and its relationship to surrounding thalamic nuclear groups are described. Nucleus rotundus in Caiman can be subdivided into three areas: (1) an outer shell; (2) an inner core; and (3) a cell poor zone located between the shell and core. Most rotundal core neurons were round, fusiform, triangular, pear-shaped, or elliptical. Core neurons were not distributed evenly throughout the nucleus but, in many instances, were arranged in clusters composed of two to ten neurons. Quantitative measurements of area, perimeter, and eccentricity (greatest width/greatest length), which served as an index of cell roundness, were made on rotundal core neuron profiles in transverse, sagittal, and horizontal planes of section. Qualitative and quantitative observations were not appreciably different regardless of the plane of orientation. Both qualitative and quantitative data suggest that relay cells located in the core of nucleus rotundus are not a homogeneous population of neurons but comprise several subtypes.

  18. 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.

  19. Dynamics of strange, charm and high momentum hadrons in relativistic nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Cassing, W.; Gallmeister, K.; Bratkovskaya, E. L.; Greiner, C.; Stöcker, H.

    2004-07-01

    We investigate hadron production and attenuation of hadrons with strange and charm quarks (or antiquarks) as well as high transverse momentum hadrons in relativistic nucleus-nucleus collisions from 2 A GeV to 21.3 A TeV within two independent transport approaches (UrQMD and HSD). Both transport models are based on quark, diquark, string and hadronic degrees of freedom, but do not include any explicit phase transition to a quark-gluon plasma. From our dynamical calculations we find that both models do not describe the maximum in the K+/ π+ ratio at 20-30 A GeV in central Au+Au collisions found experimentally, though the excitation functions of strange mesons are reproduced well in HSD and UrQMD. Furthermore, the transport calculations show that the charmonium recreation by D+ D¯→J/Ψ+ meson reactions is comparable to the dissociation by ‘comoving’ mesons at RHIC energies contrary to SPS energies. This leads to the final result that the total J/ Ψ suppression as a function of centrality at RHIC should be less than the suppression seen at SPS energies where the ‘comover’ dissociation is substantial and the backward channels play no role. Furthermore, our transport calculations-in comparison to experimental data on transverse momentum spectra from pp, d+Au and Au+Au reactions-show that pre-hadronic effects are responsible for both the hardening of the hadron spectra for low transverse momenta (Cronin effect) as well as the suppression of high pT hadrons. The mutual interactions of formed hadrons are found to be negligible in central Au+Au collisions at s=200 GeV for p T≥6 GeV/c and the sizeable suppression seen experimentally is attributed to a large extent to the interactions of ‘leading’ pre-hadrons with the dense environment.

  20. 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

  1. The subthalamic nucleus influences visuospatial attention in humans.

    PubMed

    Schmalbach, Barbara; Günther, Veronika; Raethjen, Jan; Wailke, Stefanie; Falk, Daniela; Deuschl, Günther; Witt, Karsten

    2014-03-01

    Spatial attention is a lateralized feature of the human brain. Whereas the role of cortical areas of the nondominant hemisphere on spatial attention has been investigated in detail, the impact of the BG, and more precisely the subthalamic nucleus, on signs and symptoms of spatial attention is not well understood. Here we used unilateral deep brain stimulation of the subthalamic nucleus to reversibly, specifically, and intraindividually modify the neuronal BG outflow and its consequences on signs and symptoms of visuospatial attention in patients suffering from Parkinson disease. We tested 13 patients with Parkinson disease and chronic deep brain stimulation in three stimulation settings: unilateral right and left deep brain stimulation of the subthalamic nucleus as well as bilateral deep brain stimulation of the subthalamic nucleus. In all three stimulation settings, the patients viewed a set of pictures while an eye-tracker system recorded eye movements. During the exploration of the visual stimuli, we analyzed the time spent in each visual hemispace, as well as the number, duration, amplitude, peak velocity, acceleration peak, and speed of saccades. In the unilateral left-sided stimulation setting, patients show a shorter ipsilateral exploration time of the extrapersonal space, whereas number, duration, and speed of saccades did not differ between the different stimulation settings. These results demonstrated reduced visuospatial attention toward the side contralateral to the right subthalamic nucleus that was not being stimulated in a unilateral left-sided stimulation. Turning on the right stimulator, the reduced visuospatial attention vanished. These results support the involvement of the subthalamic nucleus in modulating spatial attention. Therefore, the subthalamic nucleus is part of the subcortical network that subserves spatial attention.

  2. The red nucleus and the rubrospinal projection in the mouse.

    PubMed

    Liang, Huazheng; Paxinos, George; Watson, Charles

    2012-04-01

    We studied the organization and spinal projection of the mouse red nucleus with a range of techniques (Nissl stain, immunofluorescence, retrograde tracer injections into the spinal cord, anterograde tracer injections into the red nucleus, and in situ hybridization) and counted the number of neurons in the red nucleus (3,200.9 ± 230.8). We found that the rubrospinal neurons were mainly located in the parvicellular region of the red nucleus, more lateral in the rostral part and more medial in the caudal part. Labeled neurons were least common in the rostral and caudal most parts of the red nucleus. Neurons projecting to the cervical cord were predominantly dorsomedially placed and neurons projecting to the lumbar cord were predominantly ventrolaterally placed. Immunofluorescence staining with SMI-32 antibody showed that ~60% of SMI-32-positive neurons were cervical cord-projecting neurons and 24% were lumbar cord-projecting neurons. SMI-32-positive neurons were mainly located in the caudomedial part of the red nucleus. A study of vGluT2 expression showed that the number and location of glutamatergic neurons matched with those of the rubrospinal neurons. In the anterograde tracing experiments, rubrospinal fibers travelled in the dorsal portion of the lateral funiculus, between the lateral spinal nucleus and the calretinin-positive fibers of the lateral funiculus. Rubrospinal fibers terminated in contralateral laminae 5, 6, and the dorsal part of lamina 7 at all spinal cord levels. A few fibers could be seen next to the neurons in the dorsolateral part of lamina 9 at levels of C8-T1 (hand motor neurons) and L5-L6 (foot motor neurons), which is consistent with a view that rubrospinal fibers may play a role in distal limb movement in rodents.

  3. 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

  4. Development of the ventromedial nucleus of the hypothalamus.

    PubMed

    McClellan, Kristy M; Parker, Keith L; Tobet, Stuart

    2006-07-01

    The ventromedial nucleus of the hypothalamus (VMH) is important in the regulation of female sexual behavior, feeding, energy balance, and cardiovascular function. It is a highly conserved nucleus across species and a good model for studying neuronal organization into nuclei. Expression of various transcription factors, receptors, and neurotransmitters are important for the development of this nucleus and for mapping the position of identified cells within the nucleus. The VMH is subdivided into regions, all of which may project to specific locations to carry out various functions. For example, the ventrolateral quadrant contains a subset of neurons that highly express estrogen receptors. These neurons specifically are involved in the lordosis response pathway through projections to other estrogen receptor containing regions. In development, neurons that form the VMH generate from the proliferative zone surrounding the third ventricle. Neurons then migrate along radial glial fibers to final positions within the nucleus. Migration and positioning of neurons is an important step in setting up connections to and from the VMH and hence in its function. As compared to other developing brain regions, cell death may play a minor role in sculpting the VMH. We review the processes involved in forming a functional nuclear group and some of the factors known to be involved particularly focusing on the positioning of identified neurons within the VMH.

  5. 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.

  6. 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.

  7. Growth dynamics of the developing lateral geniculate nucleus.

    PubMed

    Williams, A L; Jeffery, G

    2001-02-12

    Segregated binocular maps in the lateral geniculate nucleus (LGN) develop from stages where they initially completely overlap. Here, we show that segregation occurs at different rates across the depth of the nucleus and that the volume of the ipsilateral projection does not decrease significantly during this period, rather LGN volume expands markedly and its shape changes. Hence, we have examined the differential growth of the ferret LGN during the process of segregation by using novel shape modelling techniques. These have facilitated quantification of its three-dimensional structure at successive developmental stages as well as the definition of growth vectors which illustrate shape change. This has been undertaken in direct representations of the LGN and those normalised for size and orientation. Spatiotemporal aspects of shape change have then been compared with different measurements of its cellular population. Initial stages of segregation are associated with a large expansion of the rostrocaudal axis of the nucleus along which segregation takes place, and an expansion of caudal regions that will eventually contain the binocular representation. Later stages are associated with dorsoventral expansions and a consolidation of the rostrocaudal axis. The pace of shape change peaks toward the end of the period of segregation when the nucleus has adopted approximately 50% of its adult shape. After segregation, nuclear growth is mainly isotropic. The mature shape of the nucleus is achieved before it reaches its full size and while cell density and cell sizes are still changing.

  8. 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

    2015-08-07

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Reaction cross sections of the deformed halo nucleus 31Ne

    NASA Astrophysics Data System (ADS)

    Urata, Y.; Hagino, K.; Sagawa, H.

    2012-10-01

    Using the Glauber theory, we calculate reaction cross sections for the deformed halo nucleus 31Ne. To this end, we assume that the 31Ne nucleus takes the 30Ne+n structure. To take into account the rotational excitation of the core nucleus 30Ne, we employ the particle-rotor model (PRM). We compare the results to those in the adiabatic limit of PRM, that is, the Nilsson model, and show that the Nilsson model works reasonably well for the reaction cross sections of 31Ne. We also investigate the dependence of the reaction cross sections on the ground-state properties of 31Ne, such as the deformation parameter and the p-wave component in the ground-state wave function.

  10. From Cytoskeleton to Gene Expression: Actin in the Nucleus.

    PubMed

    Viita, Tiina; Vartiainen, Maria K

    2017-01-01

    Although most people still associate actin mainly with the cytoskeleton, several lines of evidence, with the earliest studies dating back to decades ago, have emphasized the importance of actin also inside the cell nucleus. Actin has been linked to many gene expression processes from gene activation to chromatin remodeling, but also to maintenance of genomic integrity and intranuclear movement of chromosomes and chromosomal loci. Recent advances in visualizing different forms and dynamic properties of nuclear actin have clearly advanced our understanding of the basic concepts by which actin operates in the nucleus. In this chapter we address the different breakthroughs in nuclear actin studies, as well as discuss the regulation nuclear actin and the importance of nuclear actin dynamics in relation to its different nuclear functions. Our aim is to highlight the fact that actin should be considered as an essential component of the cell nucleus, and its nuclear actions should be taken into account also in experiments on cytoplasmic actin networks.

  11. Actin-related proteins localized in the nucleus

    PubMed Central

    Oma, Yukako

    2011-01-01

    The actin family consists of conventional actin and actin-related proteins (ARPs), and the members show moderate similarity and share the same basal structure. Following the finding of various ARPs in the cytoplasm in the 1990s, multiple subfamilies that are localized predominantly in the nucleus were identified. Consistent with these cytological observations, subsequent biochemical analyses revealed the involvement of the nuclear ARPs in ATP-dependent chromatin-remodeling and histone acetyltransferase complexes. In addition to their contribution to chromatin remodeling, recent studies have shown that nuclear ARPs have roles in the organization of the nucleus that are independent of the activity of the above-mentioned complexes. Therefore, nuclear ARPs are recognized as novel key regulators of genome function, and affect not only the remodeling of chromatin but also the spatial arrangement and dynamics of chromatin within the nucleus. PMID:21647298

  12. The double-nucleus galactic merger Mkn 463

    NASA Technical Reports Server (NTRS)

    Hutchings, J. B.; Neff, S. G.

    1989-01-01

    Deep CCD imaging in broadband and forbidden O III wavelengths of the twin-nucleus active galaxy Markarian 463 is presented. These data show that the system has triple curved tails indicative of a strong tidal interaction and probable merger. Colors, morphology, and their implications are discussed. The forbidden O III line emission is seen to be extended and linear, perhaps filling twin cones with apex at the eastern optical nucleus. It is argued that this indicates nonisotropic radiation from an obscured AGN. Spatially resolved spectroscopy on and off the nuclei reveals that the radial velocities of the gas lie in a small range, unlike some other multiple nucleus systems. The nature of the emission-line regions is discussed, along with the evolutionary state of the system indicated by the present data and IR and radio data.

  13. Models of the spin state of the comet Halley nucleus

    NASA Technical Reports Server (NTRS)

    Julian, William H.

    1990-01-01

    Eight rotation precession models of the comet Halley nucleus have been proposed by eight authors. The eight models were evaluated in relation to the constraints imposed by: (1) the observed long axis directions at the Vega 1, Vega 2, and Giotto encounters; (2) the ground based emission periods harmonically related to 7.4 days; (3) the need for a two day spin period in the analysis of the jet morphology; (4) the Smith et al. constraint on the net long axis roll between Vega 2 and Giotto; (5) the resistance of the spin state of the nucleus to change due to the torque from the jets; and (6) the 7.4 day repetition of the spatial orientation of the nucleus. The eight constraints are briefly described.

  14. 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.

  15. 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

  16. Nucleus of Comet IRAS-Araki-Alcock (1983 VII)

    SciTech Connect

    Sekanina, Z.

    1988-06-01

    Optical, radar, infrared, UV, and microwave-continuum observations of Comet IRAS-Araki-Alcok were obtained in May 1983, the week of the comet's close approach to earth. The comet has a nucleus dimension and a rotation period which are similar to those of Comet Halley, but a different morphological signature (a persisting sunward fan-shaped coma). Time variations are noted in the projected nucleus cross section. Results suggest significant limb-darkening effects in the relevant domains of radio waves, and that the comet's interior must be extremely cold. It is found that the thermal-infrared fluxes from the inner coma of the comet are dominated by the nucleus. 63 references.

  17. Response Properties of Cochlear Nucleus Neurons in Monkeys

    PubMed Central

    Roth, G. Linn; Recio, A.

    2009-01-01

    Much of what is known about how the cochlear nuclei participate in mammalian hearing comes from studies of non-primate mammalian species. To determine to what extent the cochlear nuclei of primates resemble those of other mammalian orders, we have recorded responses to sound in three primate species: marmosets, Cynomolgus macaques, and squirrel monkeys. These recordings show that the same types of temporal firing patterns are found in primates that have been described in other mammals. Responses to tones of neurons in the ventral cochlear nucleus have similar tuning, latencies, post-stimulus time and interspike interval histograms as those recorded in non-primate cochlear nucleus neurons. In the dorsal cochlear nucleus, too, responses were similar. From these results it is evident that insights gained from non-primate studies can be applied to the peripheral auditory system of primates. PMID:19531377

  18. Organization of the nucleus magnocellularis and the nucleus laminaris in the barn owl: encoding and measuring interaural time differences.

    PubMed

    Carr, C E; Boudreau, R E

    1993-08-15

    The circuit from the cochlear nucleus magnocellularis to the nucleus laminaris supports the encoding and measurement of interaural time differences in the auditory brainstem. Specializations for the encoding of temporal information include the few and/or short dendrites and thick axons of the magnocellular and laminaris neurons, and the high degree of convergence in the circuit. Magnocellular cells have large cell bodies covered with somatic spines. The cells have few dendrites, and the number of dendrites decreases from low to high best frequency regions of the nucleus. Magnocellular neurons receive both auditory nerve terminals and GABAergic terminals with symmetric synapses and terminals filled with pleomorphic vesicles. The axonal projections of magnocellular neurons to the nucleus laminaris form maps of interaural time difference. About 100 magnocellular afferents from each side converge on each laminaris neuron, and the terminals from each side do not occupy separate domains on the cell. These terminals form punctate asymmetric synapses on both the dendrites and the cell bodies of laminaris neurons. Laminaris neurons also receive GABAergic terminals which form symmetric synapses. Laminaris neurons have oval cell bodies covered with very short dendrites. The cells in the low best frequency region of the nucleus laminaris have longer dendrites.

  19. Comparison of neuronal activities of external cuneate nucleus, spinocerebellar cortex and interpositus nucleus during passive movements of the rat's forelimb.

    PubMed

    Casabona, A; Valle, M S; Bosco, G; Perciavalle, V

    2008-11-11

    In this paper we examined the neuronal activities of external cuneate nucleus, spinocerebellar Purkinje cells and interpositus nucleus during passive forelimb movements in anesthetized rats with the aim of identifying common or different patterns of activation across structures. By means of principal components analysis, we identified two main patterns of discharge which explained most of the dataset variance. One component characterized the movement-related activity of external cuneate and spinocerebellar cortical neurons, while the other reflected neuronal activity of the interpositus nucleus. We also found that both principal components were related to global forelimb kinematics but, while most of the variance of the activity of external cuneate cells and spinocerebellar Purkinje cells was explained by the limb axis orientation and orientation velocity, interpositus neurons' firing was best related to length and length velocity. This difference in the forelimb kinematics representation observed in external cuneate nucleus and spinocerebellar cortex compared with the interpositus nucleus is discussed with respect to the specific role that these structures may play also during active control of limb movements.

  20. 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. © The

  1. Slow flow of passive neutrophils and sequestered nucleus into micropipette.

    PubMed

    Kaleridis, V; Athanassiou, G; Deligianni, D; Missirlis, Y

    2010-01-01

    In the present study, the role of the nucleus and its contribution to the deformability of the passive neutrophils was investigated. To determine the rheological properties of the nucleus and of the neutrophil itself, deformation tests on single neutrophil and sequestered nucleus have been performed by micropipette under low aspiration pressure (80 Pa = 2-3 Pcr). The stiffness of the nucleus was found to be larger than that of the neutrophil, and its viscosity was found almost ten-fold higher. A subpopulation of neutrophils (Sub-A) showed two phases of deformation, a first rapid phase and a second phase with a constant deformation rate up to their full entrance, with an apparent viscosity mu app-second-Phase(N Sub-A) = 286 +/- 123 Pa x s, calculated by the liquid drop model. Another subpopulation (Sub-B) of the tested neutrophils displayed three deformation phases: a first one reflecting the rapid entry of cell into the micropipette, a second with constant deformation rate, and a third phase, with a slower, also constant, deformation rate were recorded. The corresponding apparent viscosities were found as mu app-second-Phase(N Sub-B) = 341 +/- 94 Pa x s and mu app-third-Phase(N Sub-B) = 1651 +/- 734 Pa x s. The apparent viscosity values of the neutrophilic nucleus, mu app (N nucl) = 2468 +/- 1345 Pa x s and of the whole neutrophil calculated in the third phase of deformation, mu app-third-Phase(N Sub-B) = 1651 +/- 734 Pa.s were comparable. These results support our hypothesis that the nucleus plays a significant role in the mechanical and rheological behavior of the neutrophil, especially when it has to pass through openings much smaller than its size.

  2. Morphometric study of dentate nucleus of cerebellum in Bangladeshi cadaver.

    PubMed

    Haque, M A; Khalil, M; Sultana, S Z; Mannan, S; Uddin, M M; Hossain, M; Ara, A; Choudhury, S; Shammi, N J

    2015-01-01

    This cross sectional descriptive study was done by using nonprobability sampling technique and performed by examining 63 (sixty three) cerebellum. Out of them 40 postmortem human cerebellum collected from Bangladeshi cadavers of both sexes (male 25 and female 15) age ranging from 5 to 60 years and 23 cerebellums from caesarian section of intrauterine death cases of both sexes (male 14 and female 9) age ranging from 34 to 41 weeks of gestation. Specimens were collected from dead bodies autopsied on different dates from April' 2009 to September' 2009 at the autopsy laboratory of department of Forensic Medicine and prenatal cases from Gynaecology and Obstetrics Department of Mymensingh Medical College, Mymensingh. The collected specimens were grouped into three age groups like Group A (28 to 42 weeks of gestation), Group B (5 to 30 years) and Group C (31 to 60 years) and, two sex groups (male and female) and two sides (right and left). A transverse section was made at the level of horizontal fissure, and length and breadth of dentate nucleus were measured by divider and scale. The mean (±SD) length and breadth of dentate nucleus was 8.619±2.995mm and 14.770±3.604mm respectively and it was observed that length and breadth of dentate nucleus increased with age upto certain level then slightly decreased in the late age Group C. In this study, differences of the mean length of dentate nucleus on both right and left sides were statistically moderately significant between age Groups A&B. The differences of mean breadth of dentate nucleus on both right and left side were statistically highly significant between age Groups A&B and moderately significant between age Groups A&C on right side and only significant on left side. The differences between male & female were statistically insignificant in length and breadth of dentate nucleus.

  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. Neurophysiological evaluation of the pedunculopontine nucleus in humans.

    PubMed

    Profice, P; Mazzone, P; Pilato, F; Dileone, M; Insola, A; Ranieri, F; Di Lazzaro, V

    2011-10-01

    The pedunculopontine nucleus (PPTg) is constituted by a heterogeneous cluster of neurons located in caudal mesencephalic tegmentum which projects to the thalamus to trigger thalamocortical rhythms and the brainstem to modulate muscle tone and locomotion. It has been investigated as potential deep brain stimulation (DBS) target for treating Parkinson's disease (PD) symptoms. Neurophysiological studies conducted in humans using DBS electrodes for exploring functional properties of PPTg in vivo, reviewed in this paper, demonstrated that the functional connections between PPTg and cortex, basal ganglia, brainstem network involved in sleep/wake control, and spinal cord can be explored in vivo and provided useful insights about the physiology of this nucleus and pathophysiology of PD.

  5. Recent Developments in Neutrino/Antineutrino-Nucleus Interactions

    DOE PAGES

    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.

  6. 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

  7. Functions of long noncoding RNAs in the nucleus.

    PubMed

    Yu, Bin; Shan, Ge

    2016-04-25

    Nucleus is the residence and place of work for a plethora of long noncoding RNAs. Here, we provide a summary of the functions and functional mechanisms of several relatively well studied examples of nuclear long noncoding RNAs (lncRNAs) in the nucleus, such as Xist, NEAT1, MALAT1 and TERRA. The recently identified novel EIciRNA is also highlighted. These nuclear lncRNAs play a variety of roles with diverse molecular mechanisms in animal cells. We also discuss insights and concerns about current and future studies of nuclear lnc RNAs.

  8. 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.

  9. Ice crystal and ice nucleus measurements in cap clouds

    NASA Technical Reports Server (NTRS)

    Vali, G.; Rogers, D. C.; Deshler, T. L.

    1982-01-01

    Ice nucleation in cap clouds over a mountain in Wyoming was examined with airborne instrumentation. Crosswind and wind parallel passes were made through the clouds, with data being taken on the ice crystal concentrations and sizes. A total of 141 penetrations of 26 separate days in temperatures ranging from -7 to -24 C were performed. Subsequent measurements were also made 100 km away from the mountain. The ice crystal concentrations measured showed good correlation with the ice nucleus content in winter time, midcontinental air masses in Wyoming. Further studies are recommended to determine if the variations in the ice nucleus population are the cause of the variability if ice crystal content.

  10. 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.

  11. The Development of Hypertrophic Inferior Olivary Nucleus in Oculopalatal Tremor.

    PubMed

    Jun, Bokkwan

    2016-12-01

    Oculopalatal tremor is an acquired clinical condition resulting from the interruption of the dentato-rubro-olivary neuronal pathway. The signal change in inferior olivary nucleus and its hypertrophy on magnetic resonance imaging (MRI) can be observed prior to the development of symptomatic oculopalatal tremor. This is a case of the fourth cranial nerve palsy followed by oculopalatal tremor, and increased signal intensity in inferior olivary nucleus on MRI was observed in 7 months after damage to the dentate-rubro-olivary pathway and 5 months prior to the development of oscillopsia and oculopalatal tremor.

  12. Gamma-ray spectroscopy of the nucleus 139Ce

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Căta-Danil, G.; Căta-Danil, I.; Ivaşcu, M.; Mărginean, N.; Mărginean, R.; Mihăilescu, L. C.; Rusu, C.; Suliman, G.

    2006-03-01

    Gamma-ray coincidence techniques are used to determine new level structures in the N = 81 nucleus 139Ce, at low spins and excitation energies with the 139La(p, nγ) reaction at 5.0 and 6.0MeV incident energy, and at high spins with the 130Te(12C, 3nγ) reaction at 50.5MeV, respectively. Lifetime determinations are also made in the (p, nγ) reaction with the centroid DSA method. The observed level structures are discussed by comparison with existing calculations and with those in the neighbouring nucleus 140Ce.

  13. 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

  14. Like attracts like: getting RNA processing together in the nucleus.

    PubMed

    Lewis, J D; Tollervey, D

    2000-05-26

    Structures visible within the eukaryotic nucleus have fascinated generations of biologists. Recent data show that these structures form in response to gene expression and are highly dynamic in living cells. RNA processing and assembly require many factors but the nucleus apparently lacks any active transport system to deliver these to the RNAs. Instead, processing factors move by diffusion but are concentrated by transient association with functionally related components. At sites of high activity this gives rise to visible structures, with components in dynamic equilibrium with the surrounding nucleoplasm. Processing factors are recruited from this pool by cooperative binding to RNA substrates.

  15. Morphology of multiple-nucleus brightest cluster galaxies

    SciTech Connect

    Lauer, T.R.

    1988-02-01

    The morphology of high SNR CCD images of 16 multiple-nucleus brightest cluster galaxies is studied using an algorithm that models images of the systems as the line-of-sight superposition of normal elliptical galaxies. The algorithm is applied initially to the classic multiple-nucleus cD galaxy in A2199. Evidence is found suggestive of deep interpenetrating high-speed encounters by its secondaries. The interactions effects studied include noncentric isophotes, brightness profile effects, excess light around primary galaxies, and dynamical friction wakes. The results show that in many cases multiple systems are interacting systems. 42 references.

  16. The morphology of multiple-nucleus brightest cluster galaxies

    NASA Technical Reports Server (NTRS)

    Lauer, Tod R.

    1988-01-01

    The morphology of high SNR CCD images of 16 multiple-nucleus brightest cluster galaxies is studied using an algorithm that models images of the systems as the line-of-sight superposition of normal elliptical galaxies. The algorithm is applied initially to the classic multiple-nucleus cD galaxy in A2199. Evidence is found suggestive of deep interpenetrating high-speed encounters by its secondaries. The interactions effects studied include noncentric isophotes, brightness profile effects, excess light around primary galaxies, and dynamical friction wakes. The results show that in many cases multiple systems are interacting systems.

  17. 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.

  18. Dual efferent projections of the trigeminal principal sensory nucleus to the thalamic ventroposteromedial nucleus in the squirrel monkey.

    PubMed

    Ganchrow, D; Mehler, W R

    1986-07-24

    Anterograde degeneration methods demonstrated two efferent components from the trigeminal principal sensory nucleus (PrV) to the thalamic ventroposteromedial nucleus (VPM) in the squirrel monkey: fibers from the dorsal PrV coursed within the central tegmental tract and terminated in a dorsoventromedial strip of the ipsilateral VPM; fibers from the ventral PrV mainly decussated caudal to the interpeduncular nucleus and terminated in the contralateral VPM exclusive of the sector receiving the dorsal PrV component, contralaterally. Adjacent Nissl sections showed an apparent increase in glial profiles accompanying an intense somal staining among the deafferented neuronal population in the VPM, coextensive with those regions in the VPM exhibiting terminal field degeneration.

  19. [Analgesic action of microinjection of neurokinin A into the lateral reticular nucleus and nucleus raphe magnus in rats].

    PubMed

    Yan, G P; Zhao, Y; Huang, Q E; Chen, W M

    1996-10-01

    Using the microinjection technique, the analgesic effect of neurokinin A (NKA) microinjected into the lateral reticular nucleus (LRN) and nucleus raphe magnus (NRM) was investigated in lightly pentobarbital-anesthetized rats using tail flick latency (TFL) as an index. Microinjection of NKA (0.5 microgram/0.5 microliter) into LRN significantly increased TFL lasting for 10 min (n = 12, P < 0.001). Microinjection of the same amount of NKA into NRM also produced evident increase in TFL for 5 min (n = 13, P < 0.001). The results indicate that NKA modulates pain reaction in both LRN and NRM in rats.

  20. [Repeated exposure in hypergravity: morphology of locus coeruleus, hypothalamic paraventricular nucleus and vagal nerve dorsal nucleus in rats].

    PubMed

    Krasnov, I B; Fidelina, O V; Gorbatiuk, O S; Vikhreva, O V

    2000-01-01

    As compared to analogous single rotation at 2 g and in contrast to 5-d single and repeated exposures to Coriolis accelerations, repeated 5-day hypergravity (2 g generated by centrifuge rotation) gave rise to structural alterations in rat's neurons of locus coeruleus, vasopressinergic neurons of the lateral magnocellular subnucleus paraventricular nucleus and nervi vagi dorsal nucleus suggesting involvement of these structures of brain in the mechanism of facilitation of adaptation to repeated long-term hypergravity. Results of the study point to the ability of mammals to remember changes in gravity. Findings of the study may help develop an algorithm of intermittent exposure to artificial gravity aboard space vehicle.

  1. Study of the variability of the nucleus of Centaurus A.

    NASA Astrophysics Data System (ADS)

    Fernandes de Mello Rabaca, D.; Abraham, Z.

    1990-11-01

    ABSTRACT. This work consists in the study of the variability of the nucleus of the peculiar galaxy NGC 5128 (Centaurus A) at the radio continuum frequency of 43 GHz. The data were obtained with the 13.7 m itapetinga Radiotelescope. The radio source presents a pair of inner radio lobes and a compact variable nucleus. The observational technique used was scans through the inner radio lobes and the nucleus. The quasi- simultaneous measurements of the flux density of each source allowed us to derive accurately the relative flux between them, and to obtain the real variability of the nucleus. RESUMO. Este trabalho consiste no estudo da variabilidade do nucleo da galaxia peculiar NGC 5128 (Centaurus A) no de radio na de 43 GHz. Os dados foram obtidos com 0 Radiotelescopio do Itapetinga. A radio fonte apresenta um par de lobulos internos e um nucleo compacto variavel. A tetnica observacional utilizada foi a de varreduras passando pelos lobulos e pelo nucleo. As medidas quase simultaneas da densidade de fluxo de cada fonte permitiu obter precisa- mente 0 fluxo relativo entre elas e a variabilidade real do nucleo. Keq woit : GALAXIES-RADIO

  2. 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.

  3. mRNA-Producing Pseudo-nucleus System.

    PubMed

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

    2015-11-04

    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.

  4. Antidromic activation of the isthmo-optic nucleus

    PubMed Central

    Holden, A. L.

    1968-01-01

    1. This paper describes experiments carried out to record from output cells in the isthmo-optic nucleus. 2. One-hundred and twenty-seven axonal responses were fired at fixed latency from the optic nerve-head. 3. Ninety-nine cell responses were fired trans-synaptically from the optic nerve-head. 4. Ninety-four cells were activated antidromically from the optic nerve-head. 5. Tectal tracks could be recognized by the field potential profile of the N-wave, R-wave and P-wave, and by the occurrence of fixed latency axonal responses and trans-synaptically fired cells. 6. Tectal tracks were verified histologically. 7. Tracks yielding antidromically activated cells were traced histologically to the isthmo-optic nucleus. 8. The antidromic A-wave could be recorded from the nucleus, corresponding in timing to the invasion of cell bodies. 9. Somatic records in the nucleus could be recognized by their duration, conformation, and A—B blocking. 10. When antidromic discharge was interacted with orthodromic firing, collision evidence could be provided, showing that the orthodromic impulse travels centrifugally to the retina. ImagesFig. 3Fig. 4 PMID:5675042

  5. 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.

  6. A continuing controversy: Has the cometary nucleus been resolved?

    NASA Technical Reports Server (NTRS)

    Sekanina, Z.

    1976-01-01

    Evidence is presented for classifying cometary nuclei into two basic types, described by core mantle and coreless models. Mass loss related nongravitational effects in a comet's motion as a function of time are included in considering gradual evaporation of an icy envelope surrounding the meteoric matrix in the core of the nucleus.

  7. Altered morphology of the nucleus accumbens in persistent developmental stuttering.

    PubMed

    Neef, Nicole E; Bütfering, Christoph; Auer, Tibor; Metzger, F Luise; Euler, Harald A; Frahm, Jens; Paulus, Walter; Sommer, Martin

    2017-05-24

    Neuroimaging studies in persistent developmental stuttering repeatedly report altered basal ganglia functions. Together with thalamus and cerebellum, these structures mediate sensorimotor functions and thus represent a plausible link between stuttering and neuroanatomy. However, stuttering is a complex, multifactorial disorder. Besides sensorimotor functions, emotional and social-motivational factors constitute major aspects of the disorder. Here, we investigated cortical and subcortical gray matter regions to study whether persistent developmental stuttering is also linked to alterations of limbic structures. The study included 33 right-handed participants who stutter and 34 right-handed control participants matched for sex, age, and education. Structural images were acquired using magnetic resonance imaging to estimate volumetric characteristics of the nucleus accumbens, hippocampus, amygdala, pallidum, putamen, caudate nucleus, and thalamus. Volumetric comparisons and vertex-based shape comparisons revealed structural differences. The right nucleus accumbens was larger in participants who stutter compared to controls. Recent theories of basal ganglia functions suggest that the nucleus accumbens is a motivation-to-movement interface. A speaker intends to reach communicative goals, but stuttering can derail these efforts. It is therefore highly plausible to find alterations in the motivation-to-movement interface in stuttering. While behavioral studies of stuttering sought to find links between the limbic and sensorimotor system, we provide the first neuroimaging evidence of alterations in the limbic system. Thus, our findings might initialize a unified neurobiological framework of persistent developmental stuttering that integrates sensorimotor and social-motivational neuroanatomical circuitries. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. High-spin states in the 94Nb nucleus

    NASA Astrophysics Data System (ADS)

    Mărginean, N.; Bucurescu, D.; Căta-Danil, Ghe.; Căta-Danil, I.; Ivaşcu, M.; Ur, C. A.

    2000-09-01

    High-spin states have been studied for the first time in the 94Nb nucleus with the reaction 82Se(19F,α3nγ) at 68 MeV. A cascade of transitions has been observed, based on the (6)+ ground state and extending up to 6.5 MeV excitation and spin of about 19.

  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. 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.

  11. Motility proteins and the origin of the nucleus.

    PubMed

    Dolan, Michael F; Melnitsky, Hannah; Margulis, Lynn; Kolnicki, Robin

    2002-11-01

    Hypotheses on the origin of eukaryotic cells must account for the origin of the microtubular cytoskeletal structures (including the mitotic spindle, undulipodium/cilium (so-called flagellum) and other structures underlain by the 9(2)+2 microtubular axoneme) in addition to the membrane-bounded nucleus. Whereas bacteria with membrane-bounded nucleoids have been described, no precedent for mitotic, cytoskeletal, or axonemal microtubular structures are known in prokaryotes. Molecular phylogenetic analyses indicate that the cells of the earliest-branching lineages of eukaryotes contain the karyomastigont cytoskeletal system. These protist cells divide via an extranuclear spindle and a persistent nuclear membrane. We suggest that this association between the centriole/kinetosome axoneme (undulipodium) and the nucleus existed from the earliest stage of eukaryotic cell evolution. We interpret the karyomastigont to be a legacy of the symbiosis between thermoacidophilic archaebacteria and motile eubacteria from which the first eukaryote evolved. Mutually inconsistent hypotheses for the origin of the nucleus are reviewed and sequenced proteins of cell motility are discussed because of their potential value in resolving this problem. A correlation of fossil evidence with modern cell and microbiological studies leads us to the karyomastigont theory of the origin of the nucleus.

  12. Calcium-regulated import of myosin IC into the nucleus.

    PubMed

    Maly, Ivan V; Hofmann, Wilma A

    2016-06-01

    Myosin IC is a molecular motor involved in intracellular transport, cell motility, and transcription. Its mechanical properties are regulated by calcium via calmodulin binding, and its functions in the nucleus depend on import from the cytoplasm. The import has recently been shown to be mediated by the nuclear localization signal located within the calmodulin-binding domain. In the present paper, it is demonstrated that mutations in the calmodulin-binding sequence shift the intracellular distribution of myosin IC to the nucleus. The redistribution is displayed by isoform B, described originally as the "nuclear myosin," but is particularly pronounced with isoform C, the normally cytoplasmic isoform. Furthermore, experimental elevation of the intracellular calcium concentration induces a rapid import of myosin into the nucleus. The import is blocked by the importin β inhibitor importazole. These findings are consistent with a mechanism whereby calmodulin binding prevents recognition of the nuclear localization sequence by importin β, and the steric inhibition of import is released by cell signaling leading to the intracellular calcium elevation. The results establish a mechanistic connection between the calcium regulation of the motor function of myosin IC in the cytoplasm and the induction of its import into the nucleus. © 2016 Wiley Periodicals, Inc.

  13. Piecemeal Microautophagy of the Nucleus Requires the Core Macroautophagy Genes

    PubMed Central

    Krick, R.; Muehe, Y.; Prick, T.; Bremer, S.; Schlotterhose, P.; Eskelinen, E.-L.; Millen, J.; Goldfarb, D. S.

    2008-01-01

    Autophagy is a diverse family of processes that transport cytoplasm and organelles into the lysosome/vacuole lumen for degradation. During macroautophagy cargo is packaged in autophagosomes that fuse with the lysosome/vacuole. During microautophagy cargo is directly engulfed by the lysosome/vacuole membrane. Piecemeal microautophagy of the nucleus (PMN) occurs in Saccharomyces cerevisiae at nucleus-vacuole (NV) junctions and results in the pinching-off and release into the vacuole of nonessential portions of the nucleus. Previous studies concluded macroautophagy ATG genes are not absolutely required for PMN. Here we report using two biochemical assays that PMN is efficiently inhibited in atg mutant cells: PMN blebs are produced, but vesicles are rarely released into the vacuole lumen. Electron microscopy of arrested PMN structures in atg7, atg8, and atg9 mutant cells suggests that NV-junction–associated micronuclei may normally be released from the nucleus before their complete enclosure by the vacuole membrane. In this regard PMN is similar to the microautophagy of peroxisomes (micropexophagy), where the side of the peroxisome opposite the engulfing vacuole is capped by a structure called the “micropexophagy-specific membrane apparatus” (MIPA). The MIPA contains Atg proteins and facilitates terminal enclosure and fusion steps. PMN does not require the complete vacuole homotypic fusion genes. We conclude that a spectrum of ATG genes is required for the terminal vacuole enclosure and fusion stages of PMN. PMID:18701704

  14. 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.

  15. Turn Up the Volume: Uncovering Nucleus Size Control Mechanisms.

    PubMed

    Good, Matthew C

    2015-06-08

    Reporting in Developmental Cell, Hara and Merten (2015) apply the use of microfabrication and in vitro analysis in cell-free extracts to the old problem of nuclear size control. The authors make insights into the regulation of nuclear growth that potentially explain the widely reported correlation between nucleus size and cell size.

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

    NASA Astrophysics Data System (ADS)

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

    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

  17. 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.

  18. Subthalamic nucleus stimulation in severe obsessive-compulsive disorder.

    PubMed

    Mallet, Luc; Polosan, Mircea; Jaafari, Nematollah; Baup, Nicolas; Welter, Marie-Laure; Fontaine, Denys; du Montcel, Sophie Tezenas; Yelnik, Jérôme; Chéreau, Isabelle; Arbus, Christophe; Raoul, Sylvie; Aouizerate, Bruno; Damier, Philippe; Chabardès, Stephan; Czernecki, Virginie; Ardouin, Claire; Krebs, Marie-Odile; Bardinet, Eric; Chaynes, Patrick; Burbaud, Pierre; Cornu, Philippe; Derost, Philippe; Bougerol, Thierry; Bataille, Benoit; Mattei, Vianney; Dormont, Didier; Devaux, Bertrand; Vérin, Marc; Houeto, Jean-Luc; Pollak, Pierre; Benabid, Alim-Louis; Agid, Yves; Krack, Paul; Millet, Bruno; Pelissolo, Antoine

    2008-11-13

    Severe, refractory obsessive-compulsive disorder (OCD) is a disabling condition. Stimulation of the subthalamic nucleus, a procedure that is already validated for the treatment of movement disorders, has been proposed as a therapeutic option. In this 10-month, crossover, double-blind, multicenter study assessing the efficacy and safety of stimulation of the subthalamic nucleus, we randomly assigned eight patients with highly refractory OCD to undergo active stimulation of the subthalamic nucleus followed by sham stimulation and eight to undergo sham stimulation followed by active stimulation. The primary outcome measure was the severity of OCD, as assessed by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), at the end of two 3-month periods. General psychopathologic findings, functioning, and tolerance were assessed with the use of standardized psychiatric scales, the Global Assessment of Functioning (GAF) scale, and neuropsychological tests. After active stimulation of the subthalamic nucleus, the Y-BOCS score (on a scale from 0 to 40, with lower scores indicating less severe symptoms) was significantly lower than the score after sham stimulation (mean [+/-SD], 19+/-8 vs. 28+/-7; P=0.01), and the GAF score (on a scale from 1 to 90, with higher scores indicating higher levels of functioning) was significantly higher (56+/-14 vs. 43+/-8, P=0.005). The ratings of neuropsychological measures, depression, and anxiety were not modified by stimulation. There were 15 serious adverse events overall, including 1 intracerebral hemorrhage and 2 infections; there were also 23 nonserious adverse events. These preliminary findings suggest that stimulation of the subthalamic nucleus may reduce the symptoms of severe forms of OCD but is associated with a substantial risk of serious adverse events. (ClinicalTrials.gov number, NCT00169377.) 2008 Massachusetts Medical Society

  19. Ultrastructural study of the nucleus Cuneiformis in the cat.

    PubMed

    Gioia, M; Bianchi, R

    1987-01-01

    The Cuneiformis nucleus (Cu.n.) is a reticular nucleus of the mesencephalic tegmentum which is involved in several functions and particularly in locomotor activities. While the physiological properties and the nervous connections of the nucleus have been studied, there is no data about its ultrastructure. Therefore, we investigated this region in cat at the electron microscope and with morphoquantitative methods to clarify its ultrastructural organization and particularly the characteristics of its synaptic complex. The neurons are small and medium in size, with a high nucleo-cytoplasmic ratio and a modest rough endoplasmic reticulum organization. The neuropil is very extensive. Myelinated axons are very numerous. Dendritic profiles whose plasmalemma is almost completely covered by synaptic boutons are observed frequently. There are few somatic synapses; 81% have symmetrical junctions and 23% have round vesicles only. There are numerous synapses in the neuropil, 40% having asymmetrical junctions and 60% containing round vesicles only. The greater functional complexity indicated by the morphological data and the greater extension of the neuropil synapses with respect to that of the somatic ones, suggest that the neuropil is the main site of modulation and integration of the inputs to the nucleus. A highly significant statistical difference between the sizes of the somatic vesicles and those of the neuropil was found. This may point to the presence of distinct populations of vesicles, which may be correlated with the variety of substances (neurotransmitters, neuropeptides etc ...) found in the nucleus. The remarkable ultrastructural similarity between the Cu.n. and the periaqueductal gray matter is discussed.

  20. Cytoskeletal tension induces the polarized architecture of the nucleus

    PubMed Central

    Kim, Dong-Hwee; Wirtz, Denis

    2016-01-01

    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. PMID:25701041

  1. Structures and functions in the crowded nucleus: new biophysical insights

    NASA Astrophysics Data System (ADS)

    Hancock, Ronald

    2014-09-01

    Concepts and methods from the physical sciences have catalysed remarkable progress in understanding the cell nucleus in recent years. To share this excitement with physicists and encourage their interest in this field, this review offers an overview of how the physics which underlies structures and functions in the nucleus is becoming more clear thanks to methods which have been developed to simulate and study macromolecules, polymers, and colloids. The environment in the nucleus is very crowded with macromolecules, making entropic (depletion) forces major determinants of interactions. Simulation and experiments are consistent with their key role in forming membraneless compartments such as nucleoli, PML and Cajal bodies, and discrete "territories" for chromosomes. The chromosomes, giant linear polyelectrolyte polymers, exist in vivo in a state like a polymer melt. Looped conformations are predicted in crowded conditions, and have been confirmed experimentally and are central to the regulation of gene expression. Polymer theory has revealed how the chromosomes are so highly compacted in the nucleus, forming a "crumpled globule" with fractal properties which avoids knots and entanglements in DNA while allowing facile accessibility for its replication and transcription. Entropic repulsion between looped polymers can explain the confinement of each chromosome to a discrete region of the nucleus. Crowding and looping are predicted to facilitate finding the specific targets of factors which modulate activities of DNA. Simulation shows that entropic effects contribute to finding and repairing potentially lethal double-strand breaks in DNA by increasing the mobility of the broken ends, favouring their juxtaposition for repair. Signaling pathways are strongly influenced by crowding, which favours a processive mode of response (consecutive reactions without releasing substrates). This new information contributes to understanding the sometimes counter-intuitive consequences.

  2. Critical evaluation of the anatomical location of the Barrington nucleus: relevance for deep brain stimulation surgery of pedunculopontine tegmental nucleus.

    PubMed

    Blanco, Lisette; Yuste, Jose Enrique; Carrillo-de Sauvage, María Angeles; Gómez, Aurora; Fernández-Villalba, Emiliano; Avilés-Olmos, Itciar; Limousin, Patricia; Zrinzo, Ludvic; Herrero, María Trinidad

    2013-09-05

    Deep brain stimulation (DBS) has become the standard surgical procedure for advanced Parkinson's disease (PD). Recently, the pedunculopontine tegmental nucleus (PPN) has emerged as a potential target for DBS in patients whose quality of life is compromised by freezing of gait and falls. To date, only a few groups have published their long-term clinical experience with PPN stimulation. Bearing in mind that the Barrington (Bar) nucleus and some adjacent nuclei (also known as the micturition centre) are close to the PPN and may be affected by DBS, the aim of the present study was to review the anatomical location of this structure in human and other species. To this end, the Bar nucleus area was analysed in mouse, monkey and human tissues, paying particular attention to the anatomical position in humans, where it has been largely overlooked. Results confirm that anatomical location renders the Bar nucleus susceptible to influence by the PPN DBS lead or to diffusion of electrical current. This may have an undesirable impact on the quality of life of patients.

  3. 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

  4. 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

  5. Regional difference in sex steroid action on formation of morphological sex differences in the anteroventral periventricular nucleus and principal nucleus of the bed nucleus of the stria terminalis.

    PubMed

    Kanaya, Moeko; Tsuda, Mumeko C; Sagoshi, Shoko; Nagata, Kazuyo; Morimoto, Chihiro; Thu, Chaw Kyi Tha; Toda, Katsumi; Kato, Shigeaki; Ogawa, Sonoko; Tsukahara, Shinji

    2014-01-01

    Sex steroid action is critical to form sexually dimorphic nuclei, although it is not fully understood. We previously reported that masculinization of the principal nucleus of the bed nucleus of the stria terminalis (BNSTp), which is larger and has more neurons in males than in females, involves aromatized testosterone that acts via estrogen receptor-α (ERα), but not estrogen receptor-β (ERβ). Here, we examined sex steroid action on the formation of the anteroventral periventricular nucleus (AVPV) that is larger and has more neurons in females. Morphometrical analysis of transgenic mice lacking aromatase, ERα, or ERβ genes revealed that the volume and neuron number of the male AVPV were significantly increased by deletion of aromatase and ERα genes, but not the ERβ gene. We further examined the AVPV and BNSTp of androgen receptor knockout (ARKO) mice. The volume and neuron number of the male BNSTp were smaller in ARKO mice than those in wild-type mice, while no significant effect of ARKO was found on the AVPV and female BNSTp. We also examined aromatase, ERα, and AR mRNA levels in the AVPV and BNSTp of wild-type and ARKO mice on embryonic day (ED) 18 and postnatal day (PD) 4. AR mRNA in the BNSTp and AVPV of wild-type mice was not expressed on ED18 and emerged on PD4. In the AVPV, the aromatase mRNA level was higher on ED18, although the ERα mRNA level was higher on PD4 without any effect of AR gene deletion. Aromatase and ERα mRNA levels in the male BNSTp were significantly increased on PD4 by AR gene deletion. These results suggest that estradiol signaling via ERα during the perinatal period and testosterone signaling via AR during the postnatal period are required for masculinization of the BNSTp, whereas the former is sufficient to defeminize the AVPV.

  6. Regional Difference in Sex Steroid Action on Formation of Morphological Sex Differences in the Anteroventral Periventricular Nucleus and Principal Nucleus of the Bed Nucleus of the Stria Terminalis

    PubMed Central

    Kanaya, Moeko; Tsuda, Mumeko C.; Sagoshi, Shoko; Nagata, Kazuyo; Morimoto, Chihiro; Tha Thu, Chaw Kyi; Toda, Katsumi; Kato, Shigeaki; Ogawa, Sonoko; Tsukahara, Shinji

    2014-01-01

    Sex steroid action is critical to form sexually dimorphic nuclei, although it is not fully understood. We previously reported that masculinization of the principal nucleus of the bed nucleus of the stria terminalis (BNSTp), which is larger and has more neurons in males than in females, involves aromatized testosterone that acts via estrogen receptor-α (ERα), but not estrogen receptor-β (ERβ). Here, we examined sex steroid action on the formation of the anteroventral periventricular nucleus (AVPV) that is larger and has more neurons in females. Morphometrical analysis of transgenic mice lacking aromatase, ERα, or ERβ genes revealed that the volume and neuron number of the male AVPV were significantly increased by deletion of aromatase and ERα genes, but not the ERβ gene. We further examined the AVPV and BNSTp of androgen receptor knockout (ARKO) mice. The volume and neuron number of the male BNSTp were smaller in ARKO mice than those in wild-type mice, while no significant effect of ARKO was found on the AVPV and female BNSTp. We also examined aromatase, ERα, and AR mRNA levels in the AVPV and BNSTp of wild-type and ARKO mice on embryonic day (ED) 18 and postnatal day (PD) 4. AR mRNA in the BNSTp and AVPV of wild-type mice was not expressed on ED18 and emerged on PD4. In the AVPV, the aromatase mRNA level was higher on ED18, although the ERα mRNA level was higher on PD4 without any effect of AR gene deletion. Aromatase and ERα mRNA levels in the male BNSTp were significantly increased on PD4 by AR gene deletion. These results suggest that estradiol signaling via ERα during the perinatal period and testosterone signaling via AR during the postnatal period are required for masculinization of the BNSTp, whereas the former is sufficient to defeminize the AVPV. PMID:25398007

  7. 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

  8. Actomyosin Pulls to Advance the Nucleus in a Migrating Tissue Cell

    PubMed Central

    Wu, Jun; Kent, Ian A.; Shekhar, Nandini; Chancellor, T.J.; Mendonca, Agnes; Dickinson, Richard B.; Lele, Tanmay P.

    2014-01-01

    The cytoskeletal forces involved in translocating the nucleus in a migrating tissue cell remain unresolved. Previous studies have variously implicated actomyosin-generated pushing or pulling forces on the nucleus, as well as pulling by nucleus-bound microtubule motors. We found that the nucleus in an isolated migrating cell can move forward without any trailing-edge detachment. When a new lamellipodium was triggered with photoactivation of Rac1, the nucleus moved toward the new lamellipodium. This forward motion required both nuclear-cytoskeletal linkages and myosin activity. Apical or basal actomyosin bundles were found not to translate with the nucleus. Although microtubules dampen fluctuations in nuclear position, they are not required for forward translocation of the nucleus during cell migration. Trailing-edge detachment and pulling with a microneedle produced motion and deformation of the nucleus suggestive of a mechanical coupling between the nucleus and the trailing edge. Significantly, decoupling the nucleus from the cytoskeleton with KASH overexpression greatly decreased the frequency of trailing-edge detachment. Collectively, these results explain how the nucleus is moved in a crawling fibroblast and raise the possibility that forces could be transmitted from the front to the back of the cell through the nucleus. PMID:24411232

  9. The Nucleus of Translating as One Critical Concern in Translation Pedagogy and Assessment.

    ERIC Educational Resources Information Center

    Hu, Helen Chau

    1999-01-01

    Studies the translation of nonliterary texts. The objective is to associate the nucleus of translating with the value of a source-language text, advancing the claim that appropriately translating the nucleus is among the most important concerns, and to propose an approach to assessment for translation quality based on how the nucleus is rendered.…

  10. Actomyosin pulls to advance the nucleus in a migrating tissue cell.

    PubMed

    Wu, Jun; Kent, Ian A; Shekhar, Nandini; Chancellor, T J; Mendonca, Agnes; Dickinson, Richard B; Lele, Tanmay P

    2014-01-07

    The cytoskeletal forces involved in translocating the nucleus in a migrating tissue cell remain unresolved. Previous studies have variously implicated actomyosin-generated pushing or pulling forces on the nucleus, as well as pulling by nucleus-bound microtubule motors. We found that the nucleus in an isolated migrating cell can move forward without any trailing-edge detachment. When a new lamellipodium was triggered with photoactivation of Rac1, the nucleus moved toward the new lamellipodium. This forward motion required both nuclear-cytoskeletal linkages and myosin activity. Apical or basal actomyosin bundles were found not to translate with the nucleus. Although microtubules dampen fluctuations in nuclear position, they are not required for forward translocation of the nucleus during cell migration. Trailing-edge detachment and pulling with a microneedle produced motion and deformation of the nucleus suggestive of a mechanical coupling between the nucleus and the trailing edge. Significantly, decoupling the nucleus from the cytoskeleton with KASH overexpression greatly decreased the frequency of trailing-edge detachment. Collectively, these results explain how the nucleus is moved in a crawling fibroblast and raise the possibility that forces could be transmitted from the front to the back of the cell through the nucleus.

  11. Glucocorticoid rhythms control the rhythm of expression of the clock protein, Period2, in oval nucleus of the bed nucleus of the stria terminalis and central nucleus of the amygdala in rats.

    PubMed

    Segall, L A; Perrin, J S; Walker, C-D; Stewart, J; Amir, S

    2006-07-07

    We investigated the involvement of the adrenal glucocorticoid, corticosterone, in the control of the rhythmic expression of the circadian clock protein, Period2, in forebrain nuclei known to be sensitive to glucocorticoids, stressors and drugs of abuse, the oval nucleus of the bed nucleus of the stria terminalis and the central nucleus of the amygdala. We found previously that the daily rhythm of Period2 in these nuclei is uniquely dependent on the integrity of the adrenal glands (Amir S, Lamont EW, Robinson B, Stewart J (2004) A circadian rhythm in the expression of PERIOD2 protein reveals a novel SCN-controlled oscillator in the oval nucleus of the bed nucleus of the stria terminalis. J Neurosci 24:781-790; Lamont EW, Robinson B, Stewart J, Amir S (2005) The central and basolateral nuclei of the amygdala exhibit opposite diurnal rhythms of expression of the clock protein Period2. Proc Natl Acad Sci U S A 102:4180-4184). We now show that, in rats, in the absence of the adrenals, corticosterone replacement via the drinking water, which is associated with daily fluctuations in corticosterone levels, restores the rhythm of Period2 in the oval nucleus of the bed nucleus of the stria terminalis and central nucleus of the amygdala. Corticosterone replacement via constant-release pellets has no effect. These results underscore the importance of circadian glucocorticoid signaling in Period2 rhythms in the oval nucleus of the bed nucleus of the stria terminalis and central nucleus of the amygdala and suggest a novel mechanism whereby stressors, drugs of abuse, and other abnormal states that affect the patterns of circulating glucocorticoids can alter the functional output of these nuclei.

  12. Experiments on parity violation in the compound nucleus

    SciTech Connect

    Bowman, J.D.

    1996-09-01

    Results from experiments that measure parity-violating longitudinal asymmetries in the scattering of epithermal neutrons from compound-nuclear resonances at the Manuel Lujan Neutron Scattering Center at Los Alamos are discussed. Parity non-conserving asymmetries have been observed for many p-wave resonances in a single target. Measurements were performed on several nuclei in the mass region of A-100 and A-230. The statistical model of the compound nucleus provides a theoretical basis for extracting mean-squared matrix elements from the experimental asymmetry data, and for interpreting the mean-squared matrix elements. The constraints on the weak meson-exchange couplings calculated from the compound-nucleus asymmetry data agree qualitatively with the results from few-body and light-nuclei experiments. For all nuclei but {sup 232}Th measured asymmetries have random signs. For {sup 232}Th eight of eight measured asymmetries are positive. This phenomenon is discussed in terms or doorway models.

  13. 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.

  14. 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

  15. 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.

  16. Direct Observation of Nanoparticle-Cancer Cell Nucleus Interactions

    PubMed Central

    Dam, Duncan Hieu M.; Lee, Jung Heon; Sisco, Patrick N.; Co, Dick T.; Zhang, Ming; Wasielewski, Michael R.; Odom, Teri W.

    2012-01-01

    We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultra-fast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy. PMID:22424173

  17. Leading neutrons from polarized proton-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

    2017-03-01

    Leading neutron production on protons is known to be subject to strong absorptive corrections, which have been under debate for a long time. On nuclear targets these corrections are significantly enhanced and push the partial cross sections of neutron production to the very periphery of the nucleus. As a result, the A-dependences of inclusive and diffractive neutron production turn out to be similar. The mechanism of π-a1 interference, which successfully explained the observed single-spin asymmetry of neutrons in polarized pp interactions, is extended here to polarized pA collisions. Corrected for nuclear effects it explains quite well the magnitude and sign of the asymmetry AN observed in inelastic events, resulting in a violent break up of the nucleus. However the excessive magnitude of AN observed in the diffractive sample, remains a challenge.

  18. 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.

  19. Volume regulation and shape bifurcation in the cell nucleus

    PubMed Central

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

    2015-01-01

    ABSTRACT 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. PMID:26243474

  20. Highlight on the dynamic organization of the nucleus.

    PubMed

    Thorpe, Stephen D; Charpentier, Myriam

    2017-01-02

    The last decade has seen rapid advances in our understanding of the proteins of the nuclear envelope, which have multiple roles including positioning the nucleus, maintaining its structural organization, and in events ranging from mitosis and meiosis to chromatin positioning and gene expression. Diverse new and stimulating results relating to nuclear organization and genome function from across kingdoms were presented in a session stream entitled "Dynamic Organization of the Nucleus" at this year's Society of Experimental Biology (SEB) meeting in Brighton, UK (July 2016). This was the first session stream run by the Nuclear Dynamics Special Interest Group, which was organized by David Evans, Katja Graumann (both Oxford Brookes University, UK) and Iris Meier (Ohio State University, USA). The session featured presentations on areas relating to nuclear organization across kingdoms including the nuclear envelope, chromatin organization, and genome function.

  1. 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.

  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. 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.

  4. The abnormal nucleus as a cause of congenital facial palsy

    PubMed Central

    Jemec, B.; Grobbelaar, A.; Harrison, D.

    2000-01-01

    BACKGROUND—Congenital facial palsy (CFP) is clinically defined as facial palsy present at birth. It is associated with considerable disfigurement and causes functional and emotional problems for the affected child. The aetiology of the majority of cases however, remains elusive.
AIMS—To investigate the role of a neuroanatomical abnormality as a cause of unilateral CFP.
METHODS—Magnetic resonance imaging (MRI) scans were performed on 21 patients with unilateral CFP. Fifteen patients had unilateral CFP only; six suffered from syndromes which can include unilateral CFP.
RESULTS—Of the 15 patients with unilateral CFP only, four (27%) had an abnormal nucleus or an abnormal weighting of this area on the MRI scan, compared to one (17%) of the remaining six patients.
CONCLUSION—Developmental abnormalities of the facial nucleus itself constitute an important, and previously ignored, cause of monosymptomatic unilateral CFP.

 PMID:10952650

  5. 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

  6. Galaxy IC 3639 with Obscured Active Galactic Nucleus

    NASA Image and Video Library

    2017-01-07

    IC 3639, a galaxy with an active galactic nucleus, is seen in this image combining data from the Hubble Space Telescope and the European Southern Observatory. This galaxy contains an example of a supermassive black hole hidden by gas and dust. Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA's Chandra X-Ray Observatory and the Japanese-led Suzaku satellite. The findings from NuSTAR, which is more sensitive to higher energy X-rays than these observatories, confirm the nature of IC 3639 as an active galactic nucleus that is heavily obscured, and intrinsically much brighter than observed. http://photojournal.jpl.nasa.gov/catalog/PIA21087

  7. Deformations and magnetic rotations in the Ni60 nucleus

    NASA Astrophysics Data System (ADS)

    Torres, D. A.; Cristancho, F.; Andersson, L.-L.; Johansson, E. K.; Rudolph, D.; Fahlander, C.; Ekman, J.; Du Rietz, R.; Andreoiu, C.; Carpenter, M. P.; Seweryniak, D.; Zhu, S.; Charity, R. J.; Chiara, C. J.; Hoel, C.; Pechenaya, O. L.; Reviol, W.; Sarantites, D. G.; Sobotka, L. G.; Baktash, C.; Yu, C.-H.; Carlsson, B. G.; Ragnarsson, I.

    2008-11-01

    Data from three experiments using the heavy-ion fusion evaporation-reaction 36Ar+28Si have been combined to study high-spin states in the residual nucleus Ni60, which is populated via the evaporation of four protons from the compound nucleus Ge64. The GAMMASPHERE array was used for all the experiments in conjunction with a 4π charged-particle detector arrays (MICROBALL, LUWUSIA) and neutron detectors (NEUTRON SHELL) to allow for the detection of γ rays in coincidence with the evaporated particles. An extended Ni60 level scheme is presented, comprising more than 270γ-ray transitions and 110 excited states. Their spins and parities have been assigned via directional correlations of γ rays emitted from oriented states. Spherical shell-model calculations in the fp-shell characterize some of the low-spin states, while the experimental results of the rotational bands are analyzed with configuration-dependent cranked Nilsson-Strutinsky calculations.

  8. 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.

  9. The size-wise nucleus: nuclear volume control in eukaryotes.

    PubMed

    Huber, Michael D; Gerace, Larry

    2007-11-19

    Eukaryotic cells have an "awareness" of their volume and organellar volumes, and maintain a nuclear size that is proportional to the total cell size. New studies in budding and fission yeast have examined the relationship between cell and nuclear volumes. It was found that the size of the nucleus remains proportional to cell size in a wide range of genetic backgrounds and growth conditions that alter cell volume and DNA content. Moreover, in multinucleated fission yeast cells, Neumann and Nurse (see p. 593 of this issue) found that the sizes of individual nuclei are controlled by the relative amount of cytoplasm surrounding each nucleus. These results highlight a role of the cytoplasm in nuclear size control.

  10. 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

  11. NN inversion potentials intermediate energy proton-nucleus elastic scattering

    SciTech Connect

    Arellano, H.F.; Brieva, F.A.; Love, W.G.; Geramb, H.V. von

    1995-10-01

    Recently developed nucleon-nucleon interactions using the quantum inverse scattering method shed new fight on the off-shell properties of the internucleon effective force for nucleon-nucleus scattering. Calculations of proton elastic scattering from {sup 40}Ca and {sup 208}Pb in the 500 MeV region show that variations in off-shell contributions are determined to a great extent by the accuracy with which the nucleon-nucleon phase shifts are reproduced. The study is based on the full-folding approach to the nucleon-nucleus optical potential which allows a deep understanding of the interplay between on- and off-shell effects in nucleon scattering. Results and the promising extension offered by the inversion potentials beyond the range of validity of the low-energy internucleon forces will be discussed.

  12. Electromagnetic properties of the Beryllium-11 nucleus in Halo EFT

    NASA Astrophysics Data System (ADS)

    Phillips, D. R.; Hammer, H.-W.

    2010-04-01

    We compute electromagnetic properties of the Beryllium-11 nucleus using an effective field theory that exploits the separation of scales in this halo system. We fix the parameters of the EFT from measured data on levels and scattering lengths in the 10Be plus neutron system. We then obtain predictions for the B(E1) strength of the 1/2+ to 1/2- transition in the 11Be nucleus. We also compute the charge radius of the ground state of 11Be. Agreement with experiment within the expected accuracy of a leading-order computation in this EFT is obtained. We also indicate how higher-order corrections that affect both s-wave and p-wave 10 Be-neutron interactions will affect our results.

  13. 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.

  14. Control of cell nucleus shapes via micropillar patterns.

    PubMed

    Pan, Zhen; Yan, Ce; Peng, Rong; Zhao, Yingchun; He, Yao; Ding, Jiandong

    2012-02-01

    We herein report a material technique to control the shapes of cell nuclei by the design of the microtopography of substrates to which the cells adhere. Poly(D,L-lactide-co-glycolide) (PLGA) micropillars or micropits of a series of height or depth were fabricated, and some surprising self deformation of the nuclei of bone marrow stromal cells (BMSCs) was found in the case of micropillars with a sufficient height. Despite severe nucleus deformation, BMSCs kept the ability of proliferation and differentiation. We further demonstrated that the shapes of cell nuclei could be regulated by the appropriate micropillar patterns. Besides circular and elliptoid shapes, some unusual nucleus shapes of BMSCs have been achieved, such as square, cross, dumbbell, and asymmetric sphere-protrusion.

  15. Direct observation of nanoparticle-cancer cell nucleus interactions.

    PubMed

    Dam, Duncan Hieu M; Lee, Jung Heon; Sisco, Patrick N; Co, Dick T; Zhang, Ming; Wasielewski, Michael R; Odom, Teri W

    2012-04-24

    We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultrafast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy.

  16. 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.

  17. 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.; hide

    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.

  18. Exporting RNA from the nucleus to the cytoplasm.

    PubMed

    Köhler, Alwin; Hurt, Ed

    2007-10-01

    The transport of RNA molecules from the nucleus to the cytoplasm is fundamental for gene expression. The different RNA species that are produced in the nucleus are exported through the nuclear pore complexes via mobile export receptors. Small RNAs (such as tRNAs and microRNAs) follow relatively simple export routes by binding directly to export receptors. Large RNAs (such as ribosomal RNAs and mRNAs) assemble into complicated ribonucleoprotein (RNP) particles and recruit their exporters via class-specific adaptor proteins. Export of mRNAs is unique as it is extensively coupled to transcription (in yeast) and splicing (in metazoa). Understanding the mechanisms that connect RNP formation with export is a major challenge in the field.

  19. Soluble spiroperidol binding factors from bovine caudate nucleus.

    PubMed

    Winkler, M H; Berl, S

    1982-09-01

    Several properties of soluble spiroperidol binding factors separated from bovine caudate nucleus have been investigated by a previously unreported procedure. Data consistent with high particle weight and rapid binding equilibration are reported for high-affinity (+)butaclamol-sensitive components of a digitonin extract. A slower sedimenting component is found that also exhibits high affinity for spiroperidol but is not sensitive to (+)butaclamol. Centrifugation of a caudate nucleus homogenate yields a supernatant that appears to contain a component that exhibits spiroperidol binding that is more sensitive to displacement by (-) than by (+)butaclamol. The procedure used effects rapid separation of bound from unbound tritiated ligand on short columns of Sephadex G-15 followed by extrusion and sectioning of the Sephadex. The radioactivity remaining with each section is determined. The procedure is very rapid; the addition of active phases or the changing of the ionic environment, which may disturb the equilibrium, is avoided; and recovery of the protein free of bound ligand is easily affected.

  20. 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.

  1. 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.

  2. 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.

  3. Exotic atoms, K-nucleus scattering and hypernuclei

    SciTech Connect

    Barnes, P. D.

    1981-01-01

    Recent progress in exotic atom physics, kaon-nucleus scattering, and hypernuclear physics is reviewed. Specific problems discussed include searches for muon-nucleon interactions beyond QED, a comparison of data and recent calculation of K/sup + -/ + /sup 12/C elastic and inelastic scattering, as well as recent studies of ..sigma.. and ..lambda.. hypernuclei including new data on the level structure of /sup 13/C/..lambda...

  4. 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.

  5. 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.

  6. 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

  7. Isospin effects in elastic proton-nucleus scattering

    NASA Astrophysics Data System (ADS)

    Chinn, C. R.; Elster, Ch.; Thaler, R. M.

    1993-05-01

    Isovector effects in proton-nucleus elastic scattering at medium energies are studied. The accuracy of the Kerman-McManus-Thaler isospin averaging procedure is found to be very good for nuclei larger than 4He. Studies of 40Ca and 208Pb suggest that the surface neutrons may be pulled in somewhat relative to the protons, although uncertainties in the detailed applicability of the present truncation of the multiple scattering treatment render firm conclusions premature.

  8. High-spin states in the 96Tc nucleus

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Căta-Danil, Gh.; Căta-Danil, I.; Ivaşcu, M.; Mărginean, N.; Rusu, C.; Stroe, L.; Ur, C. A.; Gizon, A.; Gizon, J.; Nyakó, B.; Timár, J.; Zolnai, L.; Boston, A. J.; Joss, D. T.; Paul, E. S.; Semple, A. T.; Parry, C. M.

    High-spin states in the 96Tc nucleus have been studied with the reactions 82Se(19F,5nγ) at 68 MeV and Zn(36S,αpxn) at 130 MeV. Two γ-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10 MeV and spin 21-22?.

  9. High-spin states in the 97Tc nucleus

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Gadea, A.; Căta-Danil, Ghe.; Căta-Danil, I.; Ivaşcu, M.; Mărginean, N.; Rusu, C.; Stroe, L.; Ur, C. A.

    High-spin states in the 97Tc nucleus have been studied by in-beam γ-ray spectroscopy with the reaction 82Se(19F,4nγ) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2ℎ. The observed level scheme is compared with results of shell model calculations.

  10. Ion channels at the nucleus: electrophysiology meets the genome.

    PubMed

    Matzke, Antonius J M; Weiger, Thomas M; Matzke, Marjori

    2010-07-01

    The nuclear envelope is increasingly viewed from an electrophysiological perspective by researchers interested in signal transduction pathways that influence gene transcription and other processes in the nucleus. Here, we describe evidence for ion channels and transporters in the nuclear membranes and for possible ion gating by the nuclear pores. We argue that a systems-level understanding of cellular regulation is likely to require the assimilation of nuclear electrophysiology into molecular and biochemical signaling pathways.

  11. Decay of the N =126 , 213Fr nucleus

    NASA Astrophysics Data System (ADS)

    Pragati, Deo, A. Y.; Podolyák, Zs.; Walker, P. M.; Algora, A.; Rubio, B.; Agramunt, J.; Fraile, L. M.; Al-Dahan, N.; Alkhomashi, N.; Briz, J. A.; Aguado, M. E. Estevez; Farrelly, G.; Gelletly, W.; Herlert, A.; Köster, U.; Maira, A.

    2016-12-01

    γ rays following the EC/β+ and α decay of the N = 126, 213Fr nucleus have been observed at the CERN isotope separator on-line (ISOLDE) facility with the help of γ -ray and conversion-electron spectroscopy. These γ rays establish several hitherto unknown excited states in 213Rn. Also, five new α -decay branches from the 213Fr ground state have been discovered. Shell model calculations have been performed to understand the newly observed states in 213Rn.

  12. 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.

  13. Dynamics of Galectin-3 in the Nucleus and Cytoplasm

    PubMed Central

    Haudek, Kevin C.; Spronk, Kimberly J.; Voss, Patricia G.; Patterson, Ronald J.; Wang, John L.; Arnoys, Eric J.

    2009-01-01

    This review summarizes selected studies on galectin-3 (Gal3) as an example of the dynamic behavior of a carbohydrate-binding protein in the cytoplasm and nucleus of cells. Within the 15-member galectin family of proteins, Gal3 (Mr ~30,000) is the sole representative of the chimera subclass in which a proline- and glycine-rich NH2-terminal domain is fused onto a COOH-terminal carbohydrate recognition domain responsible for binding galactose-containing glycoconjugates. The protein shuttles between the cytoplasm and nucleus on the basis of targeting signals that are recognized by importin(s) for nuclear localization and exportin-1 (CRM1) for nuclear export. Depending on the cell type, specific experimental conditions in vitro, or tissue location, Gal3 has been reported to be exclusively cytoplasmic, predominantly nuclear, or distributed between the two compartments. The nuclear versus cytoplasmic distribution of the protein must reflect, then, some balance between nuclear import and export, as well as mechanisms of cytoplasmic anchorage or binding to a nuclear component. Indeed, a number of ligands have been reported for Gal3 in the cytoplasm and in the nucleus. Most of the ligands appear to bind Gal3, however, through protein-protein interactions rather than through protein-carbohydrate recognition. In the cytoplasm, for example, Gal3 interacts with the apoptosis repressor Bcl-2 and this interaction may be involved in Gal3’s anti-apoptotic activity. In the nucleus, Gal3 is a required pre-mRNA splicing factor; the protein is incorporated into spliceosomes via its association with the U1 small nuclear ribonucleoprotein (snRNP) complex. Although the majority of these interactions occur via the carbohydrate recognition domain of Gal3 and saccharide ligands such as lactose can perturb some of these interactions, the significance of the protein’s carbohydrate-binding activity, per se, remains a challenge for future investigations. PMID:19616076

  14. Long-range rapidity correlations in hadron-nucleus interactions

    SciTech Connect

    Capella, A.; Tran Thanh Van, J.

    1984-06-01

    Long-range rapidity correlations between particles produced in proton-nucleus interactions at 200 GeV/c are studied in the multichain dual parton model. A large long-range correlation between particles produced in two rapidity intervals is predicted, provided these two rapidity intervals are properly chosen. The predicted effect is easily measurable. Predictions at 1 TeV are also given.

  15. Backward hadron production in neutrino-nucleus interactions

    SciTech Connect

    O. Benhar; S. Fantoni; G.I. Lykasov

    2000-03-01

    The production of backward pions in lepton-nucleus collisions is analyzed. We show that a large yield of high momentum backward pions can be explained by the Regge asymptotic of the distribution of nucleons carrying a large momentum fraction in the nuclear target. The calculated spectra of pions emitted in the neutrino + Ne --> muon + pion + X reaction are in satisfactory agreement with the available experimental data.

  16. K--Nucleus Potentials Consistent with Kaonic Atoms

    NASA Astrophysics Data System (ADS)

    Cieply, A.; Friedman, E.; Gal, A.; Mares, J.

    2004-03-01

    Various models of the K- nucleus potential have been compared and tested in fits to kaonic atom data. The calculations give basically two vastly different predictions for the depth of the K- optical potential at the nuclear density. The study of the (K-stop, π ) reaction could help to distinguish between K- optical potentials as the Λ -hypernuclear formation rates are sensitive to the details of the initial-state K- wave function.

  17. Increased R2* in the Caudate Nucleus of Asymptomatic Welders

    PubMed Central

    Lee, Eun-Young; Flynn, Michael R.; Du, Guangwei; Li, Yunqing; Lewis, Mechelle M.; Herring, Amy H.; Van Buren, Eric; Van Buren, Scott; Kong, Lan; Fry, Rebecca C.; Snyder, Amanda M.; Connor, James R.; Yang, Qing X.; Mailman, Richard B.; Huang, Xuemei

    2016-01-01

    Welding has been associated with neurobehavioral disorders. Welding fumes contain several metals including copper (Cu), manganese (Mn), and iron (Fe) that may interact to influence welding-related neurotoxicity. Although welding-related airborne Fe levels are about 10-fold higher than Mn, previous studies have focused on Mn and its accumulation in the basal ganglia. This study examined differences in the apparent transverse relaxation rates [R2* (1/T2*), estimate of Fe accumulation] in the basal ganglia (caudate nucleus, putamen, and globus pallidus) between welders and controls, and the dose–response relationship between estimated Fe exposure and R2* values. Occupational questionnaires estimated recent and lifetime Fe exposure, and blood Fe levels and brain magnetic resonance imaging (MRI) were obtained. Complete exposure and MRI R2* and R1 (1/T1: measure to estimate Mn accumulation) data from 42 subjects with welding exposure and 29 controls were analyzed. Welders had significantly greater exposure metrics and higher whole-blood Fe levels compared with controls. R2* in the caudate nucleus was significantly higher in welders after controlling for age, body mass index, respirator use, caudate R1, and blood metals of Cu and Mn, whereas there was no difference in R1 values in the basal ganglia between groups. The R2* in the caudate nucleus was positively correlated with whole-blood Fe concentration. This study provides the first evidence of higher R2* in the caudate nucleus of welders, which is suggestive of increased Fe accumulation in this area. Further studies are needed to replicate the findings and determine the neurobehavioral relevance. PMID:26769335

  18. 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. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  19. Coulomb-exchange contribution to proton-nucleus scattering

    SciTech Connect

    Arellano, H.F.; Love, W.G. )

    1992-02-01

    A scheme for including the Coulomb-exchange contribution in momentum-space calculations of proton-nucleus scattering is presented. The main feature of this approach is a careful treatment of the singular two-body Coulomb potential when the Fermi motion of the bound protons is treated explicitly as required by full-folding calculations of microscopic optical potentials. Analytic expressions are presented and applications are discussed.

  20. Thalamostriatal projections from the ventral anterior nucleus in the dog.

    PubMed

    Tanaka, D; Isaacson, L G; Trosko, B K

    1986-05-01

    Thalamostriatal projections from the ventral anterior nucleus (VA) were mapped by using autoradiographic and horseradish peroxidase techniques in the dog. Injections of tritiated leucine and proline into the lateral, central, and medial parts of VA resulted in anterograde label over the dorsolateral, midlateral, and dorsal parts of the head of the caudate nucleus, respectively. The dorsolateral and midlateral parts of the caudate contained the heaviest label. No silver grains were located over the medial or ventral parts of the caudate. Light to moderate label was located over the most dorsal part of the putamen. After injections of lectin-conjugated horseradish peroxidase (WGA-HRP) into the dorsolateral or intermediate areas of the head of the caudate, retrogradely labeled cells were present in the lateral and central parts of VA, respectively. In cases with dorsolateral caudate injections, labeled cells formed a narrow dorsoventrally oriented band located in the lateral part of VA whereas in the case with a larger injection into midcaudate, large numbers of labeled neurons were scattered throughout the central area of VA. Retrogradely labeled cells were also found in the rostral part of the ventral lateral nucleus (VL). Injections of WGA-HRP into the medial part of the caudate resulted in only a few labeled cells located in the dorsomedial part of VA. Combining these data with those from other studies mapping neostriatal afferents from the cerebral cortex in the dog, it is apparent that the midlateral part of the caudate receiving input from VA also receives afferents from cortical area 6. Furthermore, the dorsolateral part of the caudate that receives input from the lateral part of VA also receives afferents from cortical area 4. These results indicate that the dorsal and lateral parts of the canine caudate nucleus may constitute important links in the transmission and integration of information related to complex motor activities.

  1. BIMA CO Observations of the Starburst Nucleus of M82

    NASA Astrophysics Data System (ADS)

    Shen, Jianjun; Lo, K. Y.

    1995-04-01

    Observations with 2.5" (38 pc) resolution of the CO (J=1-0) emission from the starburst nucleus of M82, obtained with the Berkeley-Illinois-Maryland Association (BIMA) 6-element millimeter-wave array, have revealed unresolved (< 30 pc) structure in the CO emission with very high brightness temperature (up to 34 K). The new observations have also resolved the previously identified double lobe and central peak in the integrated CO intensity into many peaks that are all due to ``velocity crowding" of several velocity components. Most of the CO emitting gas could be located in molecular spiral arms at 125 pc and 390 pc from the nucleus. Outflow motion (approximately 230 km/s) of part of the molecular gas normal to the plane is also indicated. The new observations suggest that the starbursts took place within molecular spiral arms at some distance from the nucleus. The starbursts may in fact have propagated inwards. Given the substantial amount of dense molecular gas still present in the M82 starburst region, it is not clear why the starburst activity appears to have subsided.

  2. 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.

  3. The TLC: a novel auditory nucleus of the mammalian brain.

    PubMed

    Saldaña, Enrique; Viñuela, Antonio; Marshall, Allen F; Fitzpatrick, Douglas C; Aparicio, M-Auxiliadora

    2007-11-28

    We have identified a novel nucleus of the mammalian brain and termed it the tectal longitudinal column (TLC). Basic histologic stains, tract-tracing techniques and three-dimensional reconstructions reveal that the rat TLC is a narrow, elongated structure spanning the midbrain tectum longitudinally. This paired nucleus is located close to the midline, immediately dorsal to the periaqueductal gray matter. It occupies what has traditionally been considered the most medial region of the deep superior colliculus and the most medial region of the inferior colliculus. The TLC differs from the neighboring nuclei of the superior and inferior colliculi and the periaqueductal gray by its distinct connections and cytoarchitecture. Extracellular electrophysiological recordings show that TLC neurons respond to auditory stimuli with physiologic properties that differ from those of neurons in the inferior or superior colliculi. We have identified the TLC in rodents, lagomorphs, carnivores, nonhuman primates, and humans, which indicates that the nucleus is conserved across mammals. The discovery of the TLC reveals an unexpected level of longitudinal organization in the mammalian tectum and raises questions as to the participation of this mesencephalic region in essential, yet completely unexplored, aspects of multisensory and/or sensorimotor integration.

  4. Clinical outcomes of sleeveless phacotip assisted levitation of dropped nucleus.

    PubMed

    Agarwal, Amar; Narang, Priya; A Kumar, Dhivya; Agarwal, Ashvin

    2014-10-01

    To demonstrate the feasibility of a sleeveless phacotip-assisted approach to levitate dropped nucleus. This single-centre, retrospective, interventional, non-comparative case series reviewed the medical records of 34 eyes of 34 patients. Corrected and uncorrected distance visual acuity (CDVA, UDVA), early and late postoperative complications and ultrasound biomicroscopic (UBM) evaluation of the sclerotomy site was analysed. At 18 months follow-up, the mean postoperative UDVA and CDVA in Snellen's decimal equivalent was 0.42 ± 0.16 and 0.91 ± 0.2, respectively. There was a significant improvement in the UDVA (p=0.001) and CDVA (p=0.002). Nucleus drop occurred following intraoperative posterior capsular rupture in 25 eyes (73.5%), zonular weakness in 5 eyes (14.8%) and post-trauma in 4 eyes (11.7%). In the early postoperative period, corneal oedema was seen in 2 eyes, pigment dispersion in 3 eyes and vitritis in 2 eyes. There was loss of CDVA in 1 (2.9%) eye due to persistent cystoid macular oedema. UBM did not reveal any vitreous incarceration into the sclerotomy site. Dropped nucleus was successfully levitated into anterior chamber with this technique, resulting in a significant visual outcome with a favourable complication rate. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  5. 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.

  6. 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.

  7. Nucleus- and cell-specific gene expression in monkey thalamus.

    PubMed

    Murray, Karl D; Choudary, Prabhakara V; Jones, Edward G

    2007-02-06

    Nuclei of the mammalian thalamus are aggregations of neurons with unique architectures and input-output connections, yet the molecular determinants of their organizational specificity remain unknown. By comparing expression profiles of thalamus and cerebral cortex in adult rhesus monkeys, we identified transcripts that are unique to dorsal thalamus or to individual nuclei within it. Real-time quantitative PCR and in situ hybridization analyses confirmed the findings. Expression profiling of individual nuclei microdissected from the dorsal thalamus revealed additional subsets of nucleus-specific genes. Functional annotation using Gene Ontology (GO) vocabulary and Ingenuity Pathways Analysis revealed overrepresentation of GO categories related to development, morphogenesis, cell-cell interactions, and extracellular matrix within the thalamus- and nucleus-specific genes, many involved in the Wnt signaling pathway. Examples included the transcription factor TCF7L2, localized exclusively to excitatory neurons; a calmodulin-binding protein PCP4; the bone extracellular matrix molecules SPP1 and SPARC; and other genes involved in axon outgrowth and cell matrix interactions. Other nucleus-specific genes such as CBLN1 are involved in synaptogenesis. The genes identified likely underlie nuclear specification, cell phenotype, and connectivity during development and their maintenance in the adult thalamus.

  8. Nucleus caudalis lesioning: Case report of chronic traumatic headache relief

    PubMed Central

    Sandwell, Stephen E.; El-Naggar, Amr O.

    2011-01-01

    Background: The nucleus caudalis dorsal root entry zone (DREZ) surgery is used to treat intractable central craniofacial pain. This is the first journal publication of DREZ lesioning used for the long-term relief of an intractable chronic traumatic headache. Case Description: A 40-year-old female experienced new-onset bi-temporal headaches following a traumatic head injury. Despite medical treatment, her pain was severe on over 20 days per month, 3 years after the injury. The patient underwent trigeminal nucleus caudalis DREZ lesioning. Bilateral single-row lesions were made at 1-mm interval between the level of the obex and the C2 dorsal nerve roots, using angled radiofrequency electrodes, brought to 80°C for 15 seconds each, along a path 1 to 1.2 mm posterior to the accessory nerve rootlets. The headache improved, but gradually returned. Five years later, her headaches were severe on over 24 days per month. The DREZ surgery was then repeated. Her headaches improved and the relief has continued for 5 additional years. She has remained functional, with no limitation in instrumental activities of daily living. Conclusions: The nucleus caudalis DREZ surgery brought long-term relief to a patient suffering from chronic traumatic headache. PMID:22059123

  9. Presynaptic and extrasynaptic regulation of posterior nucleus of thalamus.

    PubMed

    Park, Anthony; Li, Ying; Masri, Radi; Keller, Asaf

    2017-03-22

    The posterior nucleus of thalamus (PO) is a higher-order nucleus involved in sensorimotor processing, including nociception. An important characteristic of PO is its wide range of activity profiles that vary across states of arousal, thought to underlie differences in somatosensory perception subject to attention and degree of consciousness. Further, PO loses the ability to down-regulate its activity level in some forms of chronic pain, suggesting that regulatory mechanisms underlying the normal modulation of PO activity may be pathologically altered. Yet, the mechanisms responsible for regulating such a wide dynamic range of activity are unknown. Here, we test a series of hypotheses regarding the function of several presynaptic receptors on both GABAergic and glutamatergic afferents targeting PO in mouse, using acute slice electrophysiology. We found that presynaptic GABAB receptors are present on both GABAergic and glutamatergic terminals in PO, but only those on GABAergic terminals are tonically active. We also found that release from GABAergic terminals, but not glutamatergic terminals, is suppressed by cholinergic activation, and that a subpopulation of GABAergic terminals is regulated by cannabinoids. Finally, we discovered the presence of tonic currents mediated by extrasynaptic GABAA receptors in PO that are heterogeneously distributed across the nucleus. Thus, we demonstrate that multiple regulatory mechanisms concurrently exist in PO, and we propose that regulation of inhibition, rather than excitation, is the more consequential mechanism by which PO activity can be regulated.

  10. 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.

  11. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Ground control to major TOM: mitochondria-nucleus communication.

    PubMed

    Eisenberg-Bord, Michal; Schuldiner, Maya

    2017-01-01

    Mitochondria have crucial functions in the cell, including ATP generation, iron-sulfur cluster biogenesis, nucleotide biosynthesis, and amino acid metabolism. All of these functions require tight regulation on mitochondrial activity and homeostasis. As mitochondria biogenesis is controlled by the nucleus and almost all mitochondrial proteins are encoded by nuclear genes, a tight communication network between mitochondria and the nucleus has evolved, which includes signaling cascades, proteins which are dual-localized to the two compartments, and sensing of mitochondrial products by nuclear proteins. All of these enable a crosstalk between mitochondria and the nucleus that allows the 'ground control' to get information on mitochondria's status. Such information facilitates the creation of a cellular balance of mitochondrial status with energetic needs. This communication also allows a transcriptional response in case mitochondrial function is impaired aimed to restore mitochondrial homeostasis. As mitochondrial dysfunction is related to a growing number of genetic diseases as well as neurodegenerative conditions and aging, elucidating the mechanisms governing the mitochondrial/nuclear communication should progress a better understanding of mitochondrial dysfunctions. © 2016 Federation of European Biochemical Societies.

  13. 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

  14. Structure of Tz = 3 / 2 , 33P Nucleus

    NASA Astrophysics Data System (ADS)

    Lubna, Rebeka Sultana; Tripathi, Vandana; Tabor, Samuel; Tai, Pei-Laun; Bender, Peter

    2016-03-01

    The excited states of the nucleus 33P were populated by the 18O(18O, p-2n γ)33P fusion evaporation reaction at Elab = 25 MeV.Gammasphere was used along with the particle detector Microball to detect the γ emissions in coincidence with the emitted charged particles from the compound nucleus 36S. The auxiliary detector Microball was used to select the charged particle channel and to determine the exact position and the energy of the emitted proton. The purpose of finding the position and energy of proton was to determine a more precise angle between the recoil nucleus and the emitted γ which was later employed to get a better Doppler correction. Along with the selection of the proton channel, the γ- γ coincidence technique helped to isolate 33P from the other phosphorus isotopes and also reduced the contaminations from the dominant pure neutron channels. A number of transitions and states was identified that were not observed before. The 4 π arrangement of Gammasphere offered an excellent opportunity to measure the angular distribution of the electromagnetic emissions leading to the assignment of the spins for most of the new states. The experimental observations were compared to the shell model calculation using Work supported by the U.S. National Science Foundation under Grant No. 1401574.

  15. 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

  16. Integration of sensory quanta in cuneate nucleus neurons in vivo.

    PubMed

    Bengtsson, Fredrik; Brasselet, Romain; Johansson, Roland S; Arleo, Angelo; Jörntell, Henrik

    2013-01-01

    Discriminative touch relies on afferent information carried to the central nervous system by action potentials (spikes) in ensembles of primary afferents bundled in peripheral nerves. These sensory quanta are first processed by the cuneate nucleus before the afferent information is transmitted to brain networks serving specific perceptual and sensorimotor functions. Here we report data on the integration of primary afferent synaptic inputs obtained with in vivo whole cell patch clamp recordings from the neurons of this nucleus. We find that the synaptic integration in individual cuneate neurons is dominated by 4-8 primary afferent inputs with large synaptic weights. In a simulation we show that the arrangement with a low number of primary afferent inputs can maximize transfer over the cuneate nucleus of information encoded in the spatiotemporal patterns of spikes generated when a human fingertip contact objects. Hence, the observed distributions of synaptic weights support high fidelity transfer of signals from ensembles of tactile afferents. Various anatomical estimates suggest that a cuneate neuron may receive hundreds of primary afferents rather than 4-8. Therefore, we discuss the possibility that adaptation of synaptic weight distribution, possibly involving silent synapses, may function to maximize information transfer in somatosensory pathways.

  17. The size of the nucleus increases as yeast cells grow.

    PubMed

    Jorgensen, Paul; Edgington, Nicholas P; Schneider, Brandt L; Rupes, Ivan; Tyers, Mike; Futcher, Bruce

    2007-09-01

    It is not known how the volume of the cell nucleus is set, nor how the ratio of nuclear volume to cell volume (N/C) is determined. Here, we have measured the size of the nucleus in growing cells of the budding yeast Saccharomyces cerevisiae. Analysis of mutant yeast strains spanning a range of cell sizes revealed that the ratio of average nuclear volume to average cell volume was quite consistent, with nuclear volume being approximately 7% that of cell volume. At the single cell level, nuclear and cell size were strongly correlated in growing wild-type cells, as determined by three different microscopic approaches. Even in G1-phase, nuclear volume grew, although it did not grow quite as fast as overall cell volume. DNA content did not appear to have any immediate, direct influence on nuclear size, in that nuclear size did not increase sharply during S-phase. The maintenance of nuclear size did not require continuous growth or ribosome biogenesis, as starvation and rapamycin treatment had little immediate impact on nuclear size. Blocking the nuclear export of new ribosomal subunits, among other proteins and RNAs, with leptomycin B also had no obvious effect on nuclear size. Nuclear expansion must now be factored into conceptual and mathematical models of budding yeast growth and division. These results raise questions as to the unknown force(s) that expand the nucleus as yeast cells grow.

  18. 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

  19. 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. Copyright © 2011 Wiley Periodicals, Inc.

  20. The Nuclear Option: Evidence Implicating the Cell Nucleus in Mechanotransduction.

    PubMed

    Szczesny, Spencer E; Mauck, Robert L

    2017-02-01

    Biophysical stimuli presented to cells via microenvironmental properties (e.g., alignment and stiffness) or external forces have a significant impact on cell function and behavior. Recently, the cell nucleus has been identified as a mechanosensitive organelle that contributes to the perception and response to mechanical stimuli. However, the specific mechanotransduction mechanisms that mediate these effects have not been clearly established. Here, we offer a comprehensive review of the evidence supporting (and refuting) three hypothetical nuclear mechanotransduction mechanisms: physical reorganization of chromatin, signaling at the nuclear envelope, and altered cytoskeletal structure/tension due to nuclear remodeling. Our goal is to provide a reference detailing the progress that has been made and the areas that still require investigation regarding the role of nuclear mechanotransduction in cell biology. Additionally, we will briefly discuss the role that mathematical models of cell mechanics can play in testing these hypotheses and in elucidating how biophysical stimulation of the nucleus drives changes in cell behavior. While force-induced alterations in signaling pathways involving lamina-associated polypeptides (LAPs) (e.g., emerin and histone deacetylase 3 (HDAC3)) and transcription factors (TFs) located at the nuclear envelope currently appear to be the most clearly supported mechanism of nuclear mechanotransduction, additional work is required to examine this process in detail and to more fully test alternative mechanisms. The combination of sophisticated experimental techniques and advanced mathematical models is necessary to enhance our understanding of the role of the nucleus in the mechanotransduction processes driving numerous critical cell functions.

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

    PubMed Central

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

    1988-01-01

    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. Images Fig. 1 Fig. 2 Fig. 4 PMID:3225218

  2. Disconnection of the amygdala central nucleus and the substantia innominata / nucleus basalis magnocellularis disrupts performance in a sustained attention task

    PubMed Central

    Holland, Peter C.

    2008-01-01

    The basal forebrain cholinergic system is broadly implicated in the regulation of attention. Disruptions in the function of this system produce impairments in many attentional functions, including the performance of well-learned responses under increased attentional load, and the surprise-induced enhancement of learning rate. Similarly, lesions of the amygdala central nucleus (CeA) have been found to impair attentional function in some circumstances. Here we examined the effects of lesions that disconnected CeA from the cholinergic substantia innominata/nucleus basalis magnocellularis (SI/nBM) on performance in a modified five-choice serial reaction time (5CSRT) task, thought to assess selective or sustained attention. The lesions impaired performance under conditions of increased attentional load, suggesting that a circuit that includes CeA and SI/nBM regulates these aspects of attention. PMID:17324052

  3. Distinct effect of orphanin FQ in nucleus raphe magnus and nucleus reticularis gigantocellularis on the rat tail flick reflex.

    PubMed

    Yang, Z; Zhang, Y; Wu, G

    2001-06-22

    The aim of the present study is to investigate the effects of orphanin FQ (OFQ) microinjected into the nucleus raphe magnus (NRM) and the nucleus reticularis gigantocellularis (NGC) on pain modulation. The tail-flick latency (TFL) was used as a behavioral index of nociceptive responsiveness. The result showed microinjection of OFQ into the NRM significantly increased the TFL, whereas microinjection of OFQ into the NGC decreased the TFL, suggesting the analgesic effect of OFQ in the NRM and the hyperalgesic effect of OFQ in the NGC. As there are three classes of putative pain modulating neurons in the rostral ventromedial medulla (RVM), the hyperalgesic or analgesic effect of OFQ in the RVM might depend upon the different class of the neurons being acted.

  4. [Extracellular aminoacids in the amygdala and nucleus accumbens in the rat during acute pain].

    PubMed

    Silva, Elizabeth; Hernández, Luis

    2007-06-01

    In the present experiments extracellular arginine, glutamate and aspartate were studied in the basolateral nucleus of the amygdala and core of the nucleus accumbens during the formalin test (phase I). A combination of capillary zone electrophoresis with laser induced fluorescence detection and microdialysis in freely moving rats was used. Glutamate and arginine significantly increased in the nucleus accumbens after formalin injection; glutamate, arginine and aspartate significantly increased in the basolateral nucleus of the amygdala, after formalin injection. These experiments suggest that rapid neurotransmitters changes observed in the nucleus accumbens and amygdala, are possibly related to immobility and emotional states such as anxiety, aversion and/or depression caused by pain.

  5. Long noncoding RNAs coordinate functions between mitochondria and the nucleus.

    PubMed

    Dong, Yaru; Yoshitomi, Takeshi; Hu, Ji-Fan; Cui, Jizhe

    2017-08-23

    In animal cells, mitochondria are the primary powerhouses and metabolic factories. They also contain genomes and can produce mitochondrial-specific nucleic acids and proteins. To maintain homeostasis of the entire cell, an intense cross-talk between mitochondria and the nucleus, mediated by encoded noncoding RNAs (ncRNAs), as well as proteins, is required. Long ncRNAs (lncRNAs) contain characteristic structures, and they are involved in the regulation of almost every stage of gene expression, as well as being implicated in a variety of disease states, such as cancer. In the coordinated signaling system, several lncRNAs, transcribed in the nucleus but residing in mitochondria, play a key role in regulating mitochondrial functions or dynamics. For example, RMRP, a component of the mitochondrial RNase MRP, is important for mitochondrial DNA replication and RNA processing, and the steroid receptor RNA activator, SRA, is a key modulator of hormone signaling and is present in both the nucleus and mitochondria. Some RNA-binding proteins maybe play a role in the lncRNAs transport system, such as HuR, GRSF1, SHARP, SLIRP, PPR, and PNPASE. Furthermore, a series of nuclear DNA-encoded lncRNAs were implicated in mitochondria-mediated apoptosis, mitochondrial bioenergetics and biosynthesis, and glutamine metabolism. The mitochondrial genome can also encode a set of lncRNAs, and they are divided into three categories: (1) lncND5, lncND6, and lncCyt b RNA; (2) chimeric mitochondrial DNA-encoded lncRNAs; and (3) putative mitochondrial DNA-encoded lncRNAs. It has been reported that the mitochondrial DNA-encoded lncRNAs appear to operate in the nucleus. The molecular mechanisms underlying trafficking of the mitochondrial DNA-encoded lncRNAs to the nucleus in mammals are only now beginning to emerge. In conclusion, both nuclear- and mitochondrial DNA-encoded lncRNAs mediate an intense intercompartmental cross-talk, which opens a rich field for investigation of the mechanism

  6. 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

  7. 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.

  8. Reliability of nucleus-to-cell and nucleus-to-cytoplasm calculations for conjunctival impression cytology specimens.

    PubMed

    Doughty, Michael J

    2012-07-01

    To assess the outcome of two different nucleo-cytoplasmic ratio calculations in relation to the number of cells measured from conjunctival impression cytology (CIC) images. CIC from the exposed nasal bulbar conjunctiva surface was undertaken on 40 young adults using a Millcell(®)-CM filter; the filters were stained with Giemsa, colour images taken of the cells in a monolayer at 200 X magnification, graded by the Nelson scale and then a projection overlay method used to outline the cell and nucleus borders. Nucleo-cytoplasmic ratios were calculated based on literal interpretation of the term (i.e. N/CYT = nucleus area/[cell area - nucleus area]) as well as based on cell area (i.e. N/CELL = nucleus area/cell area). A range of N/CYT or N/CELL values are expected for all cells, regardless of squamous metaplasia grade, with slightly greater heterogeneity expected from N/CYT calculations. The difference between the two calculations gets progressively less as the squamous metaplasia grade increases. For all grades of cells, these ratios could be determined to within approximately ±1% if adequate numbers of cells were measured (i.e. 75, 65, 50 and 35 for grade 0 to grade 3 cells respectively). If fewer cells are measured, then the variability in N/CELL or N/CYT calculations can be expected to increase. In assessments of nucleo-cytoplasmic ratios, it is important that the calculation used be specified and that the numbers of cells measured be provided.

  9. 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.

  10. Study of the peculiarities of multiparticle production via event-by-event analysis in asymmetric nucleus-nucleus interactions

    NASA Astrophysics Data System (ADS)

    Fedosimova, Anastasiya; Gaitinov, Adigam; Grushevskaya, Ekaterina; Lebedev, Igor

    2017-06-01

    In this work the study on the peculiarities of multiparticle production in interactions of asymmetric nuclei to search for unusual features of such interactions, is performed. A research of long-range and short-range multiparticle correlations in the pseudorapidity distribution of secondary particles on the basis of analysis of individual interactions of nuclei of 197 Au at energy 10.7 AGeV with photoemulsion nuclei, is carried out. Events with long-range multiparticle correlations (LC), short-range multiparticle correlations (SC) and mixed type (MT) in pseudorapidity distribution of secondary particles, are selected by the Hurst method in accordance with Hurst curve behavior. These types have significantly different characteristics. At first, they have different fragmentation parameters. Events of LC type are processes of full destruction of the projectile nucleus, in which multicharge fragments are absent. In events of mixed type several multicharge fragments of projectile nucleus are discovered. Secondly, these two types have significantly different multiplicity distribution. The mean multiplicity of LC type events is significantly more than in mixed type events. On the basis of research of the dependence of multiplicity versus target-nuclei fragments number for events of various types it is revealed, that the most considerable multiparticle correlations are observed in interactions of the mixed type, which correspond to the central collisions of gold nuclei and nuclei of CNO-group, i.e. nuclei with strongly asymmetric volume, nuclear mass, charge, etc. Such events are characterised by full destruction of the target-nucleus and the disintegration of the projectile-nucleus on several multi-charged fragments.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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.

  12. GABA and glycine receptors in the nucleus ambiguus mediate tachycardia elicited by chemical stimulation of the hypothalamic arcuate nucleus.

    PubMed

    Chitravanshi, Vineet C; Kawabe, Kazumi; Sapru, Hreday N

    2015-07-01

    We have previously reported that stimulation of the hypothalamic arcuate nucleus (ARCN) by microinjections of N-methyl-d-aspartic acid (NMDA) elicits tachycardia, which is partially mediated via inhibition of vagal inputs to the heart. The neuronal pools and neurotransmitters in them mediating tachycardia elicited from the ARCN have not been identified. We tested the hypothesis that the tachycardia elicited from the ARCN may be mediated by inhibitory neurotransmitters in the nucleus ambiguus (nAmb). Experiments were done in urethane-anesthetized, artificially ventilated, male Wistar rats. In separate groups of rats, unilateral and bilateral microinjections of muscimol (1 mM), gabazine (0.01 mM), and strychnine (0.5 mM) into the nAmb significantly attenuated tachycardia elicited by unilateral microinjections of NMDA (10 mM) into the ARCN. Histological examination of the brains showed that the microinjections sites were within the targeted nuclei. Retrograde anatomic tracing from the nAmb revealed direct bilateral projections from the ARCN and hypothalamic paraventricular nucleus to the nAmb. The results of the present study suggest that tachycardia elicited by stimulation of the ARCN by microinjections of NMDA is mediated via GABAA and glycine receptors located in the nAmb.

  13. Volumetric alterations in the nucleus accumbens and caudate nucleus in bulimia nervosa: a structural magnetic resonance imaging study.

    PubMed

    Coutinho, Joana; Ramos, Ana Filipa; Maia, Liliana; Castro, Liliana; Conceição, Eva; Geliebter, Allan; Machado, Paulo P P; Gonçalves, Óscar; Sampaio, Adriana

    2015-03-01

    Bulimia nervosa (BN) is an eating disorder characterized by recurrent episodes of binge eating and inappropriate compensatory behaviors (such as purging, fasting, or excessive exercise) to prevent weight gain. BN has been associated with deficits in inhibitory control processes. The basal ganglia specifically, the nucleus accumbens (NAc) and the caudate nucleus (CN) are part of the frontostriatal circuits involved in inhibitory control. The main goal of this study was to investigate the presence of morphological alterations in the NAc and the CN in a sample of patients diagnosed with BN. Forty-one female participants, 21 diagnosed with BN and 20 healthy matched controls (HC), underwent a structural magnetic resonance imaging (MRI) acquisition and clinical assessment. The NAc and the CN were manually segmented using the software Slicer 3D. The results reveal a significant volumetric decrease in the CN and a preserved NAc volume in BN compared to the control group. These findings suggest a contributory role of the caudate nucleus part of the dorsal striatum in the psychopathology of BN. © 2014 Wiley Periodicals, Inc.

  14. 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.

  15. The Double Nucleus and Central Black Hole of M31

    NASA Astrophysics Data System (ADS)

    Kormendy, John; Bender, Ralf

    1999-09-01

    New spectroscopy of M31 supports Tremaine's model in which both nuclei are parts of a single eccentric disk of stars orbiting the black hole (BH). The kinematics and Hubble Space Telescope photometry are used to measure the offset of the BH from the center of mass. This confirms that the BH mass is ~3×107 Msolar by a technique that is nearly independent of stellar-dynamical models. We present spectroscopy of the nucleus of M31 obtained with the Canada-France-Hawaii Telescope and Subarcsecond Imaging Spectrograph. Spectra at the Ca infrared triplet lines (seeing σ*=0.27") are used to measure the stellar kinematics, and spectra at the Mg I b lines (σ*=0.31") are used to measure metallicities. We also measure nonparametric line-of-sight velocity distributions (LOSVDs). All spectra confirm the steep rotation and velocity dispersion gradients that imply that M31 contains a 3.3×107 Msolar central dark object. At σ*=0.27", the maximum bulge-subtracted rotation velocity of the nucleus is 233+/-4 km s-1 on the P2 side, and the maximum velocity dispersion is 287+/-9 km s-1. The dispersion peak is displaced by 0.20"+/-0.03" from the velocity center in the direction opposite to P1, confirming a result by Bacon and coworkers. The higher surface brightness nucleus, P1, is colder than the bulge, with σ~=100 km s-1 at r~=1''. Cold light from P1 contributes at the velocity center; this explains part of the σ(r) asymmetry. The nucleus is cold at r>~1'' on both sides of the center. Our results are used to test Tremaine's model in which the double nucleus is a single eccentric disk of stars orbiting the BH. (1) The model predicts that the velocity center of the nucleus is displaced by 0.2" from P2 toward P1. Our observations show a displacement of 0.08"+/-0.01" before bulge subtraction and 0.10"+/-0.01" after bulge subtraction. (2) The model predicts a minimum σ~=135 km s-1 at P1. We observe σ=123+/-2 km s-1. Observations (1) and (2) may be reconciled with the model if its

  16. Chronic cocaine-regulated epigenomic changes in mouse nucleus accumbens

    PubMed Central

    2014-01-01

    Background Increasing evidence supports a role for altered gene expression in mediating the lasting effects of cocaine on the brain, and recent work has demonstrated the involvement of chromatin modifications in these alterations. However, all such studies to date have been restricted by their reliance on microarray technologies that have intrinsic limitations. Results We use next generation sequencing methods, RNA-seq and ChIP-seq for RNA polymerase II and several histone methylation marks, to obtain a more complete view of cocaine-induced changes in gene expression and associated adaptations in numerous modes of chromatin regulation in the mouse nucleus accumbens, a key brain reward region. We demonstrate an unexpectedly large number of pre-mRNA splicing alterations in response to repeated cocaine treatment. In addition, we identify combinations of chromatin changes, or signatures, that correlate with cocaine-dependent regulation of gene expression, including those involving pre-mRNA alternative splicing. Through bioinformatic prediction and biological validation, we identify one particular splicing factor, A2BP1(Rbfox1/Fox-1), which is enriched at genes that display certain chromatin signatures and contributes to drug-induced behavioral abnormalities. Together, this delineation of the cocaine-induced epigenome in the nucleus accumbens reveals several novel modes of regulation by which cocaine alters the brain. Conclusions We establish combinatorial chromatin and transcriptional profiles in mouse nucleus accumbens after repeated cocaine treatment. These results serve as an important resource for the field and provide a template for the analysis of other systems to reveal new transcriptional and epigenetic mechanisms of neuronal regulation. PMID:24758366

  17. COP1 re-accumulates in the nucleus under shade.

    PubMed

    Pacín, Manuel; Legris, Martina; Casal, Jorge J

    2013-08-01

    Shade-avoider plants typically respond to shade-light signals by increasing the rate of stem growth. CONSTITTUTIVE PHOTOMORPHOGENESIS 1 (COP1) is an E3 ligase involved in the ubiquitin labelling of proteins targeted for degradation. In dark-grown seedlings, COP1 accumulates in the nucleus and light exposure causes COP1 migration to the cytosol. Here, we show that in Arabidopsis thaliana, COP1 accumulates in the nucleus under natural or simulated shade, despite the presence of far-red light. In plants grown under white light, the transfer to shade-light conditions triggers an unexpectedly rapid re-accumulation of COP1 in the nucleus. The partial simulation of shade by lowering either blue or red light levels (maintaining far-red light) caused COP1 nuclear re-accumulation. Hypocotyl growth of wild-type seedlings is more sensitive to afternoon shade than to morning shade. A residual response to shade was observed in the cop1 mutant background, but these seedlings showed inverted sensitivity as they responded to morning shade and not to afternoon shade. COP1 overexpression exaggerated the wild-type pattern by enhancing afternoon sensitivity and making morning shade inhibitory of growth. COP1 nuclear re-accumulation also responded more strongly to afternoon shade than to morning shade. These results are consistent with a signalling role of COP1 in shade avoidance. We propose a function of COP1 in setting the daily patterns of sensitivity to shade in the fluctuating light environments of plant canopies.

  18. The Ying and Yang of the M 83 Nucleus

    NASA Astrophysics Data System (ADS)

    Mast, Damián; Díaz, Rubén J.; Dottori, Horacio A.; Agüero, María P.; Rodrigues, Irapuán; Albacete-Colombo, Juan F.

    2010-05-01

    The spiral galaxy M 83, an SB(rs)b at only 4.5 Mpc, is a privileged case for study of the detailed physics on spatial scales of a tenth of a parsec. With 3-D spectroscopic observations using CIRPASS on Gemini-S, we studied the ionized gas properties in J-band with spatial resolution of 0.″5 (Figure 1). The Paβ velocity field shows two dynamical centers, neither of them coincident with the bulge center, identified with the optical nucleus (ON) and the hidden nucleus (HN), with masses, within a radius of 10 pc, of MON = (1.8±0.4)× 107 M⊙ and MHN = (1.0±0.4)× 107 M⊙. Using the Paβ equivalent width together with population synthesis models, we are able to estimate the ages of both mass concentrations, TON = 8 Myr and THN =6-7 Myr. Adding complexity to this puzzling scenario, we used GMOS+Gemini imaging and spectroscopy to study the radio source J133658.3-295105 (Dottori et al. 2008) and find that Hα emission at the position of this source is redshifted by ~130 km s-1 with respect to an M 83 H II region, leading us to face the possibility of that we are witnessing the ejection of an object by gravitational recoil from the M 83 nucleus. A fit to the X-ray spectrum obtained Chandra supports the association between this source and the disk of M 83 by the presence of the Fe Kα line at 6.7 keV.

  19. 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

  20. Circadian modulation of osmoregulated firing in rat supraoptic nucleus neurones.

    PubMed

    Trudel, E; Bourque, C W

    2012-04-01

    The antidiuretic hormone vasopressin (VP) promotes water reabsorption from the kidney and levels of circulating VP are normally related linearly to plasma osmolality, aiming to maintain the latter close to a predetermined set point. Interestingly, VP levels rise also in the absence of an increase in osmolality during late sleep in various mammals, including rats and humans. This circadian rhythm is functionally important because the absence of a late night VP surge results in polyuria and disrupts sleep in humans. Previous work has indicated that the VP surge may be caused by facilitation of the central processes mediating the osmotic control of VP release, and the mechanism by which this occurs was recently studied in angled slices of rat hypothalamus that preserve intact network interactions between the suprachiasmatic nucleus (SCN; the biological clock), the organum vasculosum lamina terminalis (OVLT; the central osmosensory nucleus) and the supraoptic nucleus (SON; which contains VP-releasing neurohypophysial neurones). These studies confirmed that the electrical activity of SCN clock neurones is higher during the middle sleep period (MSP) than during the late sleep period (LSP). Moreover, they revealed that the excitation of SON neurones caused by hyperosmotic stimulation of the OVLT was greater during the LSP than during the MSP. Activation of clock neurones by repetitive electrical stimulation, or by injection of glutamate into the SCN, caused a presynaptic inhibition of glutamatergic synapses made between the axon terminals of OVLT neurones and SON neurones. Consistent with this effect, activation of clock neurones with glutamate also reduced the excitation of SON neurones caused by hyperosmotic stimulation of the OVLT. These results suggest that clock neurones in the SCN can mediate an increase in VP release through a disinhibition of excitatory synapses between the OVLT and the SON during the LSP. © 2012 The Authors. Journal of Neuroendocrinology © 2012

  1. Subthalamic nucleus, sensorimotor cortex and muscle interrelationships in Parkinson's disease.

    PubMed

    Marsden, J F; Limousin-Dowsey, P; Ashby, P; Pollak, P; Brown, P

    2001-02-01

    Ten patients with Parkinson's disease were seen following bilateral or unilateral implantation of macroelectrodes into the subthalamic nucleus. Local field potentials (LFPs) were recorded from adjacent subthalamic nucleus macroelectrode (STNME) contacts simultaneously with EEG activity over the supplementary motor (Cz-FCz) and sensorimotor (C3/4-FC3/4) areas and EMG activity from the contralateral wrist extensors during isometric and phasic wrist movements. Significant coherence was seen between STNME LFPs and Cz-FCz, STNME LFPs and C3/4-FC3/4, and STNME LFPs and EMG over the range 7-45 Hz. EEG phase-led STNME LFPs by 24.4 ms (95% confidence interval 19.8 to 29.0 ms). EMG also led STNME LFPs, but time differences tended to cluster around one of two values: 6.3 ms (-0.7 to 13.3 ms) and 46.5 ms (26.2 to 66.8 ms). Recordings from the STNME contact that demonstrated the most consistent coherence with Cz-FCz in the 15-30 Hz band coincided with the contact which, when electrically stimulated at high frequencies, produced the most effective clinical response in eight out of nine (89%) subjects (P < 0.01). Oscillatory activity at 15-30 Hz may therefore prove of use in localizing the subthalamic nucleus target that provides the best clinical effect on stimulation. These results extend the hypothesis that coherent activity may be useful in binding together related activities in simultaneously active motor centres. The presence of coherence between EEG and STNME LFPs in both the beta and the gamma band (as opposed to only the beta band between EEG and cerebellar thalamus) suggests that there may be some relative frequency selectivity in the communication between different motor structures.

  2. Separable representation of multichannel nucleon-nucleus optical potentials

    NASA Astrophysics Data System (ADS)

    Hlophe, L.; Elster, Ch.

    2017-05-01

    Background: One important ingredient for many applications of nuclear physics to astrophysics, nuclear energy, and stockpile stewardship is cross sections for reactions of neutrons with rare isotopes. Since direct measurements are often not feasible, indirect methods, e.g., (d ,p ) reactions, should be used. Those (d ,p ) reactions may be viewed as three-body reactions and described with Faddeev techniques. Purpose: Faddeev equations in momentum space have a long tradition of utilizing separable interactions in order to arrive at sets of coupled integral equations in one variable. Optical potentials representing the effective interactions in the neutron (proton) nucleus subsystem are usually non-Hermitian as well as energy dependent. Including excitations of the nucleus in the calculation requires a multichannel optical potential. The purpose of this paper is to introduce a separable, energy-dependent multichannel representation of complex, energy-dependent optical potentials that contain excitations of the nucleus and that fulfill reciprocity exactly. Methods: Momentum space Lippmann-Schwinger integral equations are solved with standard techniques to obtain the form factors for the separable representation. Results: Starting from energy-dependent multichannel optical potentials for neutron and proton scattering from 12C, separable representations based on a generalization of the Ernst-Shakin-Thaler (EST) scheme are constructed which fulfill reciprocity exactly. Applications to n +12C and p +12C scattering are investigated for energies from 0 to 50 MeV. Conclusions: We find that the energy-dependent separable representation of complex, energy-dependent phenomenological multichannel optical potentials describes scattering data with the same quality as the original potential.

  3. Maturation of firing pattern in chick vestibular nucleus neurons.

    PubMed

    Shao, M; Hirsch, J C; Peusner, K D

    2006-08-25

    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

  4. Tonotopic and somatotopic representation in the nucleus basalis of the barn owl, Tyto alba.

    PubMed

    Wild, J M; Kubke, M F; Carr, C E

    2001-01-01

    We have investigated the somatosensory and auditory representations in the nucleus basalis of the barn owl. In pigeons and finches, the nucleus basalis contains a representation of the beak and an auditory area. In the barn owl, the nucleus basalis also contains a complete somatotopic map of the head and body (as in the budgerigar), with a tonotopically organized auditory area in close proximity to the representation of the facial ruff and the preaural area. Recordings within and around the nucleus basalis revealed predominantly (about 80%) contralateral responses to somatic stimulation. The somatotopic map was oriented with the head down and rostral. Penetrations revealed an over-representation of the feet in dorsal basalis, followed by the rest of the body and wings more ventrally. Towards more rostral positions in nucleus basalis, responses from the head and beak predominated ventrally. The auditory response area was encountered below the region that responded to stimulation of the facial ruff and preaural flap regions and above a region responsive to beak stimulation. Auditory responses were tonotopically organized, with low best frequencies dorsal. Some penetrations yielded predominantly monaural responses with a fairly broad dynamic range, similar to those recorded from the ventral nucleus of the lateral lemniscus (LLV) and the cochlear nucleus angularis, whereas other penetrations contained predominantly binaural responses sensitive to interaural time differences (ITD). The physiological responses could be predicted on the basis of auditory projections to the nucleus basalis. An injection of biotinylated dextran amine (BDA) in the auditory region of nucleus basalis retrogradely labeled cells in both the caudal and rostral parts of the intermediate lateral lemniscal nucleus (LLIc and LLIr), and a few cells in the anterior part of the dorsal lateral lemniscal nucleus (LLDa, previously known as nucleus ventralis lemnisci lateralis, pars anterior, or VLVa) and

  5. Subthalamic nucleus neuronal activity in Parkinson's disease and epilepsy subjects.

    PubMed

    Montgomery, Erwin B

    2008-01-01

    Activity from 113 subthalamic nucleus (STN) neurons from two epilepsy patients and 103 neurons from 9 Parkinson's disease (PD) patients undergoing DBS surgery showed no significant differences in frequencies (PD, mean 7.5+/-7.0 spikes/s (sps), epilepsy mean 7.8+/-8.5 sps) or in the coefficients of variation of mean discharge frequencies per 1s epochs. A striking relationship between mean discharge frequencies per 1 s epochs and the standard deviations for both groups were consistent with a random Poisson processes. These and similar findings call into question theories that posit increased STN activity is causal to parkinsonism.

  6. Hypersexuality following subthalamic nucleus stimulation for Parkinson's disease.

    PubMed

    Doshi, Paresh; Bhargava, Pranshu

    2008-01-01

    Subthalamic nucleus (STN) stimulation is an established surgical treatment for Parkinson's disease (PD). Though the motor benefits of STN stimulation are well understood, its cognitive and behavioral effects are still not fully understood. Manic psychosis, hypersexuality, pathological gambling and mood swings are associated with advanced PD. There have been reports to suggest improvement or worsening in these symptoms following STN deep brain stimulation (DBS). We report two cases as the sole behavioral side-effects of STN stimulation despite good clinical improvement on long-term follow-up. These patients and literature review suggests the complex role of STN stimulation in motor and behavioral control.

  7. 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.

  8. 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.

  9. 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.

  10. Coherent neutrino-nucleus scattering and new neutrino interactions

    NASA Astrophysics Data System (ADS)

    Lindner, Manfred; Rodejohann, Werner; Xu, Xun-Jie

    2017-03-01

    We investigate the potential to probe new neutrino physics with future experiments measuring coherent neutrino-nucleus scattering. Experiments with high statistics should become feasible soon and allow to constrain parameters with unprecedented precision. Using a benchmark setup for a future experiment probing reactor neutrinos, we study the sensitivity on neutrino non-standard interactions and new exotic neutral currents (scalar, tensor, etc). Compared to Fermi interaction, percent and permille level strengths of the new interactions can be probed, superseding for some observables the limits from future neutrino oscillation experiments by up to two orders of magnitude.

  11. Neutrino-nucleus interactions and the determination of oscillation parameters

    NASA Astrophysics Data System (ADS)

    Benhar, Omar; Huber, Patrick; Mariani, Camillo; Meloni, Davide

    2017-07-01

    We review the status and prospects of theoretical studies of neutrino-nucleus interactions, and discuss the influence of the treatment of nuclear effects on the determination of oscillation parameters. The models developed to describe the variety of reaction mechanisms contributing to the nuclear cross sections are analyzed, with emphasis placed on their capability to explain the large body of available electron scattering data. The impact of the uncertainties associated with the description of nuclear structure and dynamics on the determination of oscillation parameters is illustrated through examples, and possible avenues towards a better understanding of the signals detected by accelerator-based experiments are outlined.

  12. A Numerical Modeling Approach to Cometary Nucleus Surface Roughness Determination

    NASA Astrophysics Data System (ADS)

    Höfner, S.; Vincent, J.-B.; Sierks, H.; Blum, J.

    2013-09-01

    Activity of cometary nuclei is closely linked with thermophysical processes. Main catalyst to activity is the diurnal temperature wave induced by solar heating. Highly resolved comet nucleus geometric models are used to model temperatures with flat surfacial facets taken from shape modeling approaches [1, 3]. Recent analyses of Groussin et al. [4] and Davidsson et al. [2] compared thermal inertia and surface temperatures of Tempel 1 and Hartley 2 synthetic models to those derived from spectral images. They outlined that applying beaming factors and radiative self-heating is not sufficient to understand the thermal behaviour of the nucleus surface. Regions with large incidence angles (e.g. at the morning terminator) distinctively deviate from predicted temperatures. One of the main contributions to this deviation is the effect of surface roughness with scals that are considerably smaller than the model facets. Combined with a relatively low thermal inertia, temperatures cover a wide range of values even at closest neighbourhood to each other. The radiative measurement for a distant observer unveils a smearing effect that indicates higher temperatures compared to average. The authors follow two numerical approaches to model small-scale surface roughness: (A) by using randomly generated fractal surfaces and (B) by downscaling groups of facets originating from larger shape models of Tempel 1. We apply a model that accounts for both radiative heat exchange for all facets and shadowing effects due to incoming solar radiation. These values are calculated in a thermal model. The revealed temperatures are analyzed with respect to average large-scale surface temperatures. Hence, they are compared to deviating temperatures that are measured by a distant observer that is unable to resolve sub-structure surface patterns. A parametric study varying thermal inertia and the degree of surface roughness then outlines a bandwidth of feasible surface structures and relates them to

  13. Current trajectory options for a comet nucleus sample return mission

    NASA Astrophysics Data System (ADS)

    Sauer, Carl G., Jr.

    1992-08-01

    A summary of the current trajectory options available for the ESA comet nucleus sample return mission, Rosetta, is presented. These options include direct trajectories, delta-V-EGA trajectories using a Titan IV/Centaur launch vehicle with upgraded solid rocket motors, a trajectory involving a gravity assist of the earth (VEGA) prior to comet rendezvous, and one involving an additional gravity assist of the earth (VEEGA). Other propulsion options proposed and discussed are solar electric propulsion/ballistic trajectory modes and nuclear electric propulsion trajectory modes. Tables of performance data for each of these trajectory options are given.

  14. Active galactic nucleus feedback in clusters of galaxies.

    PubMed

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

    2010-04-20

    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.

  15. [Mutations in the personality nucleus at puberty and adolescence].

    PubMed

    Schiopu, U

    1989-01-01

    The author considers that analysing the personality by means of concrete research, the axis "self-perceptual Ego and the prospective, ideal Ego" make up an operational axis included in personality nucleus. The selected interference of the alter image about the Ego permanently readjusts this axis. In this purpose an adjective checklist and the projective test TST in two alternative have been used. The author concludes that during puberty and adolescence several changes take place as far as the number of adjective used, descriptors prevailing characteristics, and affective finality are concerned.

  16. 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.

  17. Microlensing and the structure of active galactic nucleus accretion disks

    NASA Technical Reports Server (NTRS)

    Rauch, Kevin P.; Blandford, Roger D.

    1991-01-01

    Rapid variability has been reported in two of the four gravitationally lensed images of Q2237 + 0305, and this is attributed to microlensing caused by the intervening stars. The associated constraints on the source size and properties are studied and compared with a variety of stationary accretion disk models. The reported microlensing variation in Q2237 + 0305 requires the disk size to be over 3 times smaller than a blackbody disk of similar luminosity, implying that the optical emission is either nonthermal or optically tin. An exploration of nonstationary disk models including orbiting, transient hot spots leads to a similar conclusion. Implications for models of active galactic nucleus optical continua are briefly discussed.

  18. Planetary camera observations of the double nucleus of M31

    NASA Technical Reports Server (NTRS)

    Lauer, Tod R.; Faber, S. M.; Groth, Edward J.; Shaya, Edward J.; Campbell, Bel; Code, Arthur; Currie, Douglas G.; Baum, William A.; Ewald, S. P.; Hester, J. J.

    1993-01-01

    HST Planetary Camera images obtained in the V and I band for M31 show its inner nucleus to consist of two components that are separated by 0.49 arcsec. The nuclear component with lower surface brightness closely coincides with the bulge photocenter and is argued to be at the kinematic center of the galaxy. It is surmised that, if dust absorption generates the asymmetric nuclear morphology observed, the dust grain size must either be exceptionally large, or the dust optical depth must be extremely high; the higher surface-brightness and off-center nuclear component may alternatively be a separate stellar system.

  19. Sizing and shaping the nucleus: mechanisms and significance.

    PubMed

    Jevtić, Predrag; Edens, Lisa J; Vuković, Lidija D; Levy, Daniel L

    2014-06-01

    The size and shape of the nucleus are tightly regulated, indicating the physiological significance of proper nuclear morphology, yet the mechanisms and functions of nuclear size and shape regulation remain poorly understood. Correlations between altered nuclear morphology and certain disease states have long been observed, most notably many cancers are diagnosed and staged based on graded increases in nuclear size. Here we review recent studies investigating the mechanisms regulating nuclear size and shape, how mitotic events influence nuclear morphology, and the role of nuclear size and shape in subnuclear chromatin organization and cancer progression. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Modeling of the cometary nucleus-coma interface region

    NASA Technical Reports Server (NTRS)

    Gombosi, T. I.; Korosmezey, A.

    1989-01-01

    A well-developed dusty cometary atmosphere extends to distances over 4 orders of magnitude larger than the size of the nucleus. Pre-encounter models of the inner coma were based on the assumption that a spherically symmetric description was adequate to describe the dust-gas interaction region. Recent observational evidence together with a new generation of multidimensional theoretical models demonstrate that the inner cometary environment is far from spherical symmetry and a number of unexpected phenomena (dust jet broadening, subsolar dust spike formation, etc.) might play a significant role in this region.

  1. Dopamine system, cerebellum, and nucleus ruber in fish and mammals.

    PubMed

    Matsui, Hideaki

    2017-05-01

    Small teleost fish including zebrafish and medaka have been used as animal models for research because of their small body size, vast amounts of eggs produced, their rapid development, low husbandry costs, and transparency during embryogenesis. Although the body size and appearance seem different, fish and mammals including human still possess anatomical and functional similarities in their brains. This review summarizes the similarities of brain structures and functions between teleost fish and mammalian brains, focusing on the dopamine system, functional regionalization of the cerebellum, and presence of the nucleus ruber. © 2017 Japanese Society of Developmental Biologists.

  2. 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

  3. Cluster Productions in Intermediate-Energy Proton-Nucleus Reactions

    SciTech Connect

    Iwamoto, Hiroki; Uozumi, Yusuke

    2008-04-17

    We propose a model to describe cluster productions within the framework of the intranuclear cascade (INC) model. In our model, combination of the 'surface coalescence' and the 'knockout' is implemented to describe cluster productions in intermediate-energy nuclear reactions. In the present work, the basic ingredients of our INC model are defined and applied to nucleon and cluster productions for the proton-nucleus reactions. Although our INC model has some difficulties and room for improvement, it gives a good overall agreement with experimental data of not only nucleon productions but also cluster productions at intermediate energies.

  4. 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.

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

    PubMed Central

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

    2015-01-01

    ABSTRACT 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. PMID:25908852

  6. Nitric oxide in the gracile nucleus mediates depressor response to acupuncture (ST36).

    PubMed

    Chen, Shuang; Ma, Sheng-Xing

    2003-08-01

    The purpose of these studies was to determine the role of gracile nucleus and the effects of l-arginine-derived nitric oxide (NO) synthesis in the nucleus on the cardiovascular responses to electroacupuncture (EA) stimulation of "Zusanli" (ST36). Arterial blood pressure and heart rate were monitored during EA stimulation of ST36 following microinjections of agents into gracile nucleus. EA ST36 produced depressor and bradycardiac responses in anesthetized Sprague-Dawley rats. The cardiovascular responses to EA ST36 were blocked by bilateral microinjection of lidocaine into gracile nucleus. Microinjection of L-arginine into gracile nucleus facilitated the hypotensive and bradycardiac responses to EA ST36. The cardiovascular responses to EA ST36 were attenuated by bilateral microinjection of neuronal NO synthase (nNOS) antisense oligos into gracile nucleus. Microinjection of nNOS sense oligos into gracile nucleus did not alter the cardiovascular response to EA ST36. The results demonstrate that a blockade of neuronal conduction in the gracile nucleus inhibits the cardiovascular responses to EA ST36. The hypotensive and bradycardiac responses to EA ST36 are modified by influences of L-arginine-derived NO synthesis in the gracile nucleus. We conclude that NO plays an important role in mediating the cardiovascular responses to EA ST36 through gracile nucleus.

  7. 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

  8. Investigation of a central nucleus of the amygdala/dorsal raphe nucleus serotonergic circuit implicated in fear-potentiated startle

    PubMed Central

    Spannuth, Benjamin M.; Hale, Matthew W.; Evans, Andrew K.; Lukkes, Jodi L.; Campeau, Serge; Lowry, Christopher A.

    2011-01-01

    Serotonergic systems are thought to play an important role in control of motor activity and emotional states. We used a fear-potentiated startle paradigm to investigate the effects of a motor-eliciting stimulus in the presence or absence of induction of an acute fear state on serotonergic neurons in the dorsal raphe nucleus (DR) and cells in subdivisions of the central amygdaloid nucleus (CE), a structure that plays an important role in fear responses, using induction of the protein product of the immediate-early gene, c-fos. In Experiment 1 we investigated the effects of fear conditioning training, by training rats to associate a light cue (conditioned stimulus, CS; 1000 lx, 2 sec) with foot shock (0.5 s, 0.5 mA) in a single session. In Experiment 2 rats were given two training sessions identical to Experiment 1 on days 1 and 2, then tested in one of four conditions on day 3: 1) placement in the training context without exposure to either the CS or acoustic startle (AS), 2) exposure to 10 trials of the 2 s CS, 3) exposure to 40 110 dB AS trials, or 4) exposure to 40 110 dB AS trials with 10 of the trials preceded by and co-terminating with the CS. All treatments were conducted during a 20 min session. Fear conditioning training, by itself, increased c-Fos expression in multiple subdivisions of the CE and throughout the DR. In contrast, fear-potentiated startle selectively increased c-Fos expression in the medial subdivision of the CE and in serotonergic neurons in the dorsal part of the dorsal raphe nucleus (DRD). These data are consistent with previous studies demonstrating that fear-related stimuli selectively activate DRD serotonergic neurons. Further studies of this mesolimbocortical serotonergic system could have important implications for understanding mechanisms underlying vulnerability to stress-related psychiatric disorders, including anxiety and affective disorders. PMID:21277950

  9. Lateral habenula and the rostromedial tegmental nucleus innervate neurochemically distinct subdivisions of the dorsal raphe nucleus in the rat.

    PubMed

    Sego, Chemutai; Gonçalves, Luciano; Lima, Leandro; Furigo, Isadora C; Donato, Jose; Metzger, Martin

    2014-05-01

    The lateral habenula (LHb) is an epithalamic structure differentiated in a medial (LHbM) and a lateral division (LHbL). Together with the rostromedial tegmental nucleus (RMTg), the LHb has been implicated in the processing of aversive stimuli and inhibitory control of monoamine nuclei. The inhibitory LHb influence on midbrain dopamine neurons has been shown to be mainly mediated by the RMTg, a mostly GABAergic nucleus that receives a dominant input from the LHbL. Interestingly, the RMTg also projects to the dorsal raphe nucleus (DR), which also receives direct LHb projections. To compare the organization and transmitter phenotype of LHb projections to the DR, direct and indirect via the RMTg, we first placed injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin into the LHb or the RMTg. We then confirmed our findings by retrograde tracing and investigated a possible GABAergic phenotype of DR-projecting RMTg neurons by combining retrograde tracing with in situ hybridization for GAD67. We found only moderate direct LHb projections to the DR, which mainly emerged from the LHbM and were predominantly directed to the serotonin-rich caudal DR. In contrast, RMTg projections to the DR were more robust, emerged from RMTg neurons enriched in GAD67 mRNA, and were focally directed to a distinctive DR subdivision immunohistochemically characterized as poor in serotonin and enriched in presumptive glutamatergic neurons. Thus, besides its well-acknowledged role as a GABAergic control center for the ventral tegmental area (VTA)-nigra complex, our findings indicate that the RMTg is also a major GABAergic relay between the LHb and the DR.

  10. Nucleus-Dependent Valence-Space Approach to Nuclear Structure

    NASA Astrophysics Data System (ADS)

    Stroberg, S. R.; Calci, A.; Hergert, H.; Holt, J. D.; Bogner, S. K.; Roth, R.; Schwenk, A.

    2017-01-01

    We present a nucleus-dependent valence-space approach for calculating ground and excited states of nuclei, which generalizes the shell-model in-medium similarity renormalization group to an ensemble reference with fractionally filled orbitals. Because the ensemble is used only as a reference, and not to represent physical states, no symmetry restoration is required. This allows us to capture three-nucleon (3 N ) forces among valence nucleons with a valence-space Hamiltonian specifically targeted to each nucleus of interest. Predicted ground-state energies from carbon through nickel agree with results of other large-space ab initio methods, generally to the 1% level. In addition, we show that this new approach is required in order to obtain convergence for nuclei in the upper p and s d shells. Finally, we address the 1+/3+ inversion problem in 22Na and 46V. This approach extends the reach of ab initio nuclear structure calculations to essentially all light- and medium-mass nuclei.

  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. Lifetime measurements in shape transition nucleus 188Pt

    NASA Astrophysics Data System (ADS)

    Rohilla, Aman; Gupta, C. K.; Singh, R. P.; Muralithar, S.; Chakraborty, S.; Sharma, H. P.; Kumar, A.; Govil, I. M.; Biswas, D. C.; Chamoli, S. K.

    2017-04-01

    Nuclear level lifetimes of high spin states in yrast and non-yrast bands of 188Pt nucleus have been measured using recoil distance plunger setup present at IUAC, Delhi. In the experiment nuclear states of interest were populated via 174Yb(18O,4 n)188Pt reaction at a beam energy of 79MeV provided by 15 UD Pelletron accelerator. The extracted B(E2\\downarrow) values show an initial rise up to 4+ state and then a nearly constant behavior with spin along yrast band, indicating change of nuclear structure in 188Pt at low spins. The good agreement between experimental and TPSM model B(E2\\downarrow) values up to 4^+ state suggests an increase in axial deformation of the nucleus. The average absolute β2 = 0.20 (3) obtained from measured B(E2\\downarrow) values matches well the values predicted by CHFB and IBM calculations for oblate ( β2 ˜ -0.19) and prolate (β2 ˜ 0.22) shapes. As the lifetime measurements do not yield the sign of β2, no definite conclusion can be drawn on the prolate or oblate collectivity of 188Pt on the basis of present measurements.

  13. Capsaicin augments synaptic transmission in the rat medial preoptic nucleus.

    PubMed

    Karlsson, Urban; Sundgren-Andersson, Anna K; Johansson, Staffan; Krupp, Johannes J

    2005-05-10

    The medial preoptic nucleus (MPN) is the major nucleus of the preoptic area (POA), a hypothalamic area involved in the regulation of body-temperature. Injection of capsaicin into this area causes hypothermia in vivo. Capsaicin also causes glutamate release from hypothalamic slices. However, no data are available on the effect of capsaicin on synaptic transmission within the MPN. Here, we have studied the effect of exogenously applied capsaicin on spontaneous synaptic activity in hypothalamic slices of the rat. Whole-cell patch-clamp recordings were made from visually identified neurons located in the MPN. In a subset of the studied neurons, capsaicin enhanced the frequency of spontaneous glutamatergic EPSCs. Remarkably, capsaicin also increased the frequency of GABAergic IPSCs, an effect that was sensitive to removal of extracellular calcium, but insensitive to tetrodotoxin. This suggests an action of capsaicin at presynaptic GABAergic terminals. In contrast to capsaicin, the TRPV4 agonist 4alpha-PDD did not affect GABAergic IPSCs. Our results show that capsaicin directly affects synaptic transmission in the MPN, likely through actions at presynaptic terminals as well as on projecting neurons. Our data add to the growing evidence that capsaicin receptors are not only expressed in primary afferent neurons, but also contribute to synaptic processing in some CNS regions.

  14. A Golgi study of the camel cuneate nucleus.

    PubMed

    Zaqout, Sami I; Al-Hussain, Saleh M; Al-Saffar, Raith A; El-Dwairi, Qasim A

    2012-12-01

    Neurons in the cuneate nucleus of the camel brain stem were studied by Golgi method. Six types of neurons were identified based on soma size and shape, density of dendritic trees, morphology and distribution of spines, and appendages. Type I neurons had large spherical somata with somatic appendages. Dendritic appendages were predominant on proximal dendrites with terminal flower-like appendages. Type II neurons had medium to large soma. Appendages and spines were found for the soma as well as along dendrites of different orders. Axons with local branches were seen for these neurons. Type III neurons were small to medium spheroidal or triangulated with large number of spines and appendages on all parts of neurons including soma, dendrites, and initial axonal segments. Axons of these neurons branch profusely and formed rich local axonal arborizations. Type IV medium-size neurons have bipolar, round, or fusiform soma with somatic spines. Their dendrites were sparsely branching with spines and terminal side branches. Type V neurons were spheroid or triangular with small soma with somatic appendages. Their dendrites were sparsely branching and terminate as thin spiny side branches. Type VI neurons were small-size unipolar, round, or fusiform with some dendritic spines and protrusions. These findings shed some light on the structure of the cuneate nucleus of one of the largest animals (the camel). Copyright © 2012 Wiley Periodicals, Inc.

  15. Identifying folding nucleus based on residue contact networks of proteins.

    PubMed

    Li, Jie; Wang, Jun; Wang, Wei

    2008-06-01

    In the native structure of a protein, all the residues are tightly parked together in a specific order following its folding and every residue contacts with some spatially neighbor residues. A residue contact network can be constructed by defining the residues as nodes and the native contacts as edges. During the folding of small single-domain proteins, there is a set of contacts (or bonds), defined as the folding nucleus (FN), which is formed around the transition state, i.e., a rate-limiting barrier located at about the middle between the unfolded states and the native state on the free energy landscape. Such a FN plays an essential role in the folding dynamics and the residues, which form the related contacts called as folding nucleus residues (FNRs). In this work, the FNRs in proteins are identified by using quantities which characterize the topology of residue contact networks of proteins. By comparing the specificities of residues with the network quantities K(R), L(R), and D(R), up to 90% FNRs of six typical proteins found experimentally are identified. It is found that the FNRs behave the full-closeness centrals rather than degree or closeness centers in the residue contact network, implying that they are important to the folding cooperativity of proteins. Our study shows that the FNRs can be identified solely from the native structures of proteins based on the analysis of residue contact network without any knowledge of the transition state ensemble. (c) 2008 Wiley-Liss, Inc.

  16. Gustatory and homeostatic functions of the rodent parabrachial nucleus.

    PubMed

    de Araujo, Ivan E

    2009-07-01

    Previous studies demonstrate that lesions to the rodent parabrachial nucleus (PBN) disrupt the formation of gustatory-postingestive associations, while preserving gustatory and viscerosensory functions. This suggests that the rodent PBN functions essentially as an integrative circuit, supporting the conditioning of tastants to postingestive factors. In the case of primates, however, anatomical studies have failed to demonstrate gustatory projections from medullary nuclei to PBN. It should therefore be inferred that the primate PBN lacks the associative functions assigned to its rodent counterpart. Moreover, the ability of rodent midbrain dopaminergic systems to respond to the activation of palatable tastants depends on the integrity of the gustatory PBN. However, recent studies demonstrate that caloric palatable compounds do not require taste signaling to produce elevated brain dopamine levels. This raises the possibility that, in rodents, PBN neurons are important for the detection of postingestive effects of nutrients that occur independently of gustatory input. If confirmed, such function would assign non-associative roles to the rodent PBN, approximating its functional organization to its primate counterpart. We are currently testing this possibility by monitoring the behavioral responses to caloric glucose solutions in sweet-blind mice having sustained bilateral lesions to the PBN. Preliminary results indicate that the rodent PBN regulates nutrient intake even when no gustatory inputs are involved. This favors the assignment of non-gustatory, homeostatic functions to the rodent PBN during feeding, a concept that brings an additional perspective on the rodent versus primate functional discrepancy associated with the anatomy of this pontine nucleus.

  17. A model of the cell nucleus for DNA damage calculations.

    PubMed

    Nikjoo, Hooshang; Girard, Peter

    2012-01-01

    Development of a computer model of genomic deoxyribonucleic acid (DNA) in the human cell nucleus for DNA damage and repair calculations. The model comprises the human genomic DNA, chromosomal domains, and loops attached to factories. A model of canonical B-DNA was used to build the nucleosomes and the 30-nanometer solenoidal chromatin. In turn the chromatin was used to form the loops of factories in chromosome domains. The entire human genome was placed in a spherical nucleus of 10 micrometers diameter. To test the new target model, tracks of protons and alpha-particles were generated using Monte Carlo track structure codes PITS99 (Positive Ion Track Structure) and KURBUC. Damage sites induced in the genome were located and classified according to type and complexity. The three-dimensional structure of the genome starting with a canonical B-DNA model, nucleosomes, and chromatin loops in chromosomal domains are presented. The model was used to obtain frequencies of DNA damage induced by protons and alpha-particles by direct energy deposition, including single- and double-strand breaks, base damage, and clustered lesions. This three-dimensional model of the genome is the first such model using the full human genome for the next generation of more comprehensive modelling of DNA damage and repair. The model combines simple geometrical structures at the level of domains and factories with potentially full detail at the level of atoms in particular genes, allowing damage patterns in the latter to be simulated.

  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. 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

  20. [Pedunculopontine tegmental nucleus. Anatomy, functional considerations and physiopathological implications].

    PubMed

    Erro, E; Giménez-Amaya, J M

    1999-01-01

    Pedunculopontine tegmental nucleus is formed by an ensemble of cholinergic and non-cholinergic neurons located in the caudal pontomesencephalic tegmentum, surrounding the superior cerebellar peduncle. It is an integral part of the reticulate formation of the brain stem, with extensive anatomical connections and highly varied functions. By means of ascendant projections that it sends to the thalamus, it intervenes in the waking-sleep cycle. Besides, it constitutes the most caudal nucleus of the neuroaxis, receiving connections from the basal ganglia, for which reason it has attracted the interest of those researchers concerned with the study of these structures. Thanks to its reciprocal connections with the basal ganglia, as well as to its descending projections to different structures of the pons, medulla and spinal cord; it has been related to the control of locomotion. Recently, it has also been considered as a possible centre for the integration of the motor information provided by the dorsal striatum with the motivational or limbic information proceeding from the ventral striatum, to permit its direct access to bulbar or spinal motor centres. In this work we will review its anatomical and functional characteristics, as well as its implication in some diseases of the nervous system such as narcolepsy, progressive supranuclear paralysis, schizophrenia and Parkinson's disease.

  1. Deformations and magnetic rotations in the {sup 60}Ni nucleus

    SciTech Connect

    Torres, D. A.; Cristancho, F.; Andersson, L.-L.; Johansson, E. K.; Rudolph, D.; Fahlander, C.; Ekman, J.; Rietz, R. du; Andreoiu, C.; Carpenter, M. P.; Seweryniak, D.; Zhu, S.; Charity, R. J.; Chiara, C. J.; Hoel, C.; Pechenaya, O. L.; Reviol, W.; Sarantites, D. G.; Sobotka, L. G.; Baktash, C.

    2008-11-15

    Data from three experiments using the heavy-ion fusion evaporation-reaction {sup 36}Ar+{sup 28}Si have been combined to study high-spin states in the residual nucleus {sup 60}Ni, which is populated via the evaporation of four protons from the compound nucleus {sup 64}Ge. The GAMMASPHERE array was used for all the experiments in conjunction with a 4{pi} charged-particle detector arrays (MICROBALL, LUWUSIA) and neutron detectors (NEUTRON SHELL) to allow for the detection of {gamma} rays in coincidence with the evaporated particles. An extended {sup 60}Ni level scheme is presented, comprising more than 270{gamma}-ray transitions and 110 excited states. Their spins and parities have been assigned via directional correlations of {gamma} rays emitted from oriented states. Spherical shell-model calculations in the fp-shell characterize some of the low-spin states, while the experimental results of the rotational bands are analyzed with configuration-dependent cranked Nilsson-Strutinsky calculations.

  2. Spatial differences in molecular characteristics of the pontine parabrachial nucleus.

    PubMed

    Maeda, Naohiro; Onimura, Mayuko; Ohmoto, Makoto; Inui, Tadashi; Yamamoto, Takashi; Matsumoto, Ichiro; Abe, Keiko

    2009-11-03

    Neurons in the pontine parabrachial nucleus (PBN) transduce signals for the general visceral sensory, somatic sensory, gustatory, and autonomic nervous systems, and the various PBN neurons that perform these functions are intermingled. In this study, we analyzed PBN gene expression profiles in male Wistar rats and obtained data on gene expression in the PBN and the principal sensory nucleus of the trigeminal nerve (Pr5). Using these data in combination with in situ hybridization analyses, we identified genes that showed higher expression in the PBN than in Pr5. Our findings indicate that expression patterns in the PBN were different for different genes: Fxyd6, syt5, and plxnc1 were expressed in many neuron populations in the PBN, while the expression patterns of calcr and asb4 were restricted to the central lateral subnucleus and waist area. Furthermore, calcr and asb4 expression patterns were distinct from those of neurotransmitters/neuropeptides such as neurotensin and calcitonin gene-related peptides. Satb2 was specifically expressed in the waist area, which is essential for gustation. In-depth analysis of spatial distribution in the PBN enabled classification of the genes into seven characteristic spatial expression patterns. Expression signatures differed significantly in the subnuclei of the rostral half, mediodorsal half, and ventrolateral third of the PBN, indicating a correlation between the spatial arrangement of the subnuclei and the molecular characteristics of the corresponding neurons. Thus, our results provide valuable information regarding the molecular features and neurotransmission mechanisms of PBN neurons that transmit specific types of information.

  3. Signaling from the secretory granule to the nucleus

    PubMed Central

    Rajagopal, Chitra; Mains, Richard E.; Eipper, Betty A.

    2014-01-01

    Neurons and endocrine cells use a complex array of signaling molecules to communicate with each other and with various targets. The majority of these signaling molecules are stored in specialized organelles awaiting release on demand: 40–60 nm vesicles carry conventional or small molecule neurotransmitters, and 200–400 nm granules contain bioactive peptides. The supply of small molecule neurotransmitters is tightly regulated by local feedback of synthetic rates and transport processes at sites of release. The larger granules that contain bioactive peptides present the secretory cell with special challenges, since the peptide precursors are inserted into the lumen of the secretory pathway in the cell soma and undergo biosynthetic processing while being transported to distant sites for eventual secretion. One solution to this dilemma in information handling has been to employ proteolytic cleavage of secretory granule membrane proteins to produce cytosolic fragments that can signal to the nucleus, affecting gene expression. The use of regulated intramembrane proteolysis to signal from secretory granules to the nucleus is compared to its much better understood role in relaying information from the endoplasmic reticulum by SREBP and ATF6 and from the plasma membrane by Cadherins, Notch and ErbB4. PMID:22681236

  4. CTP synthase forms cytoophidia in the cytoplasm and nucleus.

    PubMed

    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. Copyright © 2014. Published by Elsevier Inc.

  5. A Dynamical Model Reveals Gene Co-Localizations in Nucleus

    PubMed Central

    Yao, Ye; Lin, Wei; Hennessy, Conor; Fraser, Peter; Feng, Jianfeng

    2011-01-01

    Co-localization of networks of genes in the nucleus is thought to play an important role in determining gene expression patterns. Based upon experimental data, we built a dynamical model to test whether pure diffusion could account for the observed co-localization of genes within a defined subnuclear region. A simple standard Brownian motion model in two and three dimensions shows that preferential co-localization is possible for co-regulated genes without any direct interaction, and suggests the occurrence may be due to a limitation in the number of available transcription factors. Experimental data of chromatin movements demonstrates that fractional rather than standard Brownian motion is more appropriate to model gene mobilizations, and we tested our dynamical model against recent static experimental data, using a sub-diffusion process by which the genes tend to colocalize more easily. Moreover, in order to compare our model with recently obtained experimental data, we studied the association level between genes and factors, and presented data supporting the validation of this dynamic model. As further applications of our model, we applied it to test against more biological observations. We found that increasing transcription factor number, rather than factory number and nucleus size, might be the reason for decreasing gene co-localization. In the scenario of frequency- or amplitude-modulation of transcription factors, our model predicted that frequency-modulation may increase the co-localization between its targeted genes. PMID:21760760

  6. Resetting a functional G1 nucleus after mitosis.

    PubMed

    de Castro, Ines J; Gokhan, Ezgi; Vagnarelli, Paola

    2016-09-01

    The maintenance of the correct cellular information goes beyond the simple transmission of an intact genetic code from one generation to the next. Epigenetic changes, topological cues and correct protein-protein interactions need to be re-established after each cell division to allow the next cell cycle to resume in the correct regulated manner. This process begins with mitotic exit and re-sets all the changes that occurred during mitosis thus restoring a functional G1 nucleus in preparation for the next cell cycle. Mitotic exit is triggered by inactivation of mitotic kinases and the reversal of their phosphorylation activities on many cellular components, from nuclear lamina to transcription factors and chromatin itself. To reverse all these phosphorylations, phosphatases act during mitotic exit in a timely and spatially controlled manner directing the events that lead to a functional G1 nucleus. In this review, we will summarise the recent developments on the control of phosphatases and their known substrates during mitotic exit, and the key steps that control the restoration of chromatin status, nuclear envelope reassembly and nuclear body re-organisation. Although pivotal work has been conducted in this area in yeast, due to differences between the mitotic exit network between yeast and vertebrates, we will mainly concentrate on the vertebrate system.

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

    PubMed

    Robleto, Karla; Thompson, Richard F

    2008-03-05

    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.

  8. Finding Hierarchical and Overlapping Dense Subgraphs using Nucleus Decompositions

    SciTech Connect

    Seshadhri, Comandur; Pinar, Ali; Sariyuce, Ahmet Erdem; Catalyurek, Umit

    2014-11-01

    Finding dense substructures in a graph is a fundamental graph mining operation, with applications in bioinformatics, social networks, and visualization to name a few. Yet most standard formulations of this problem (like clique, quasiclique, k-densest subgraph) are NP-hard. Furthermore, the goal is rarely to nd the \\true optimum", but to identify many (if not all) dense substructures, understand their distribution in the graph, and ideally determine a hierarchical structure among them. Current dense subgraph nding algorithms usually optimize some objective, and only nd a few such subgraphs without providing any hierarchy. It is also not clear how to account for overlaps in dense substructures. We de ne the nucleus decomposition of a graph, which represents the graph as a forest of nuclei. Each nucleus is a subgraph where smaller cliques are present in many larger cliques. The forest of nuclei is a hierarchy by containment, where the edge density increases as we proceed towards leaf nuclei. Sibling nuclei can have limited intersections, which allows for discovery of overlapping dense subgraphs. With the right parameters, the nuclear decomposition generalizes the classic notions of k-cores and k-trusses. We give provable e cient algorithms for nuclear decompositions, and empirically evaluate their behavior in a variety of real graphs. The tree of nuclei consistently gives a global, hierarchical snapshot of dense substructures, and outputs dense subgraphs of higher quality than other state-of-theart solutions. Our algorithm can process graphs with tens of millions of edges in less than an hour.

  9. Translating neuronal activity into dendrite elaboration: signaling to the nucleus.

    PubMed

    Redmond, Lori

    2008-01-01

    Growth and elaboration of neuronal processes is key to establishing neuronal connectivity critical for an optimally functioning nervous system. Neuronal activity clearly influences neuronal connectivity and does so via intracellular calcium signaling. A number of CaMKs and MAPKs convey the calcium signal initiated by neuronal activity. Several of these kinases interact with substrates in close proximity to the plasma membrane and alter dendrite structure locally via these local interactions. However, many calcium-activated kinases, such as Ras-MAPK and CaMKIV, target proteins in the nucleus, either by activating a downstream substrate that is a component of a signaling cascade or by directly acting within the nucleus. It is the activation of nuclear signaling and gene transcription that is thought to mediate global changes in dendrite complexity. The identification of calcium-sensitive transcription factors and transcriptional coactivators provides substantial evidence that gene transcription is a prevalent mechanism by which neuronal activity is translated into changes in dendrite complexity. The present review presents an overview of the role of neuronal activity in the development of neuronal dendrites, the signaling mechanisms that translate neuronal activity into gene transcription, and the transcribed effectors that regulate dendrite complexity. (c) 2008 S. Karger AG, Basel.

  10. 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

  11. Glucocorticoid signaling in the arcuate nucleus modulates hepatic insulin sensitivity.

    PubMed

    Yi, Chun-Xia; Foppen, Ewout; Abplanalp, William; Gao, Yuanqing; Alkemade, Anneke; la Fleur, Susanne E; Serlie, Mireille J; Fliers, Eric; Buijs, Ruud M; Tschöp, Matthias H; Kalsbeek, Andries

    2012-02-01

    Glucocorticoid receptors are highly expressed in the hypothalamic paraventricular nucleus (PVN) and arcuate nucleus (ARC). As glucocorticoids have pronounced effects on neuropeptide Y (NPY) expression and as NPY neurons projecting from the ARC to the PVN are pivotal for balancing feeding behavior and glucose metabolism, we investigated the effect of glucocorticoid signaling in these areas on endogenous glucose production (EGP) and insulin sensitivity by local retrodialysis of the glucocorticoid receptor agonist dexamethasone into the ARC or the PVN, in combination with isotope dilution and hyperinsulinemic-euglycemic clamp techniques. Retrodialysis of dexamethasone for 90 min into the ARC or the PVN did not have significant effects on basal plasma glucose concentration. During the hyperinsulinemic-euglycemic clamp, retrodialysis of dexamethasone into the ARC largely prevented the suppressive effect of hyperinsulinemia on EGP. Antagonizing the NPY1 receptors by intracerebroventricular infusion of its antagonist largely blocked the hepatic insulin resistance induced by dexamethasone in the ARC. The dexamethasone-ARC-induced inhibition of hepatic insulin sensitivity was also prevented by hepatic sympathetic denervation. These data suggest that glucocorticoid signaling specifically in the ARC neurons modulates hepatic insulin responsiveness via NPY and the sympathetic system, which may add to our understanding of the metabolic impact of clinical conditions associated with hypercortisolism.

  12. 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.

  13. The nucleus accumbens beyond the anterior commissure: implications for psychosurgery.

    PubMed

    Lucas-Neto, Lia; Mourato, Beatriz; Neto, Daniel; Oliveira, Edson; Martins, Hugo; Correia, Francisco; Gonçalves-Ferreira, António

    2014-01-01

    The nucleus accumbens (Acc) is a basal forebrain structure integrated in the dopaminergic cerebral rewarding circuits and implicated in some neuropsychiatric disorders. It has become a target for deep brain stimulation for some of these disorders when refractory to medical treatment. However, it is controversial as to which target is the best and similar results have been achieved with the stimulation of neighboring structures such as the bed nucleus of the stria terminalis (BNST). Previous studies have established the stereotactic anatomy of the human Acc, but some difficulties remain concerning its precise posterior limit, which is assumed to be at the level of the anterior commissure (AC). It is our purpose to clarify the anatomy of this zone, given the importance of its exact identification in psychosurgery. A total of 16 Acc were collected by autopsy, fixed, dissected, embedded and cut in coronal 5-µm slices. The slices were stained with hematoxylin and eosin, marked with anti-D1 and anti-D2 antibodies and analyzed under a microscope. The human Acc has the same cellular structure as the dorsal striatum, except in its posterior subcommissural part where voluminous neurons prevail, similar to and contiguous with the BNST. The Acc is longer than previously described, with a sub- and postcommissural extension behind the AC, continuous with the BNST. © 2014 S. Karger AG, Basel.

  14. 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.

  15. 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.

  16. Calcium Signaling in Synapse-to-Nucleus Communication

    PubMed Central

    Hagenston, Anna M.; Bading, Hilmar

    2011-01-01

    Changes in the intracellular concentration of calcium ions in neurons are involved in neurite growth, development, and remodeling, regulation of neuronal excitability, increases and decreases in the strength of synaptic connections, and the activation of survival and programmed cell death pathways. An important aspect of the signals that trigger these processes is that they are frequently initiated in the form of glutamatergic neurotransmission within dendritic trees, while their completion involves specific changes in the patterns of genes expressed within neuronal nuclei. Accordingly, two prominent aims of research concerned with calcium signaling in neurons are determination of the mechanisms governing information conveyance between synapse and nucleus, and discovery of the rules dictating translation of specific patterns of inputs into appropriate and specific transcriptional responses. In this article, we present an overview of the avenues by which glutamatergic excitation of dendrites may be communicated to the neuronal nucleus and the primary calcium-dependent signaling pathways by which synaptic activity can invoke changes in neuronal gene expression programs. PMID:21791697

  17. Hypoglossal nucleus projections to the rat masseter muscle.

    PubMed

    Mameli, O; Stanzani, S; Russo, A; Pellitteri, R; Spatuzza, M; Caria, M A; Mulliri, G; De Riu, P L

    2009-08-04

    We investigated in the rat whether hypoglossal innervation extended to facial muscles other than the extrinsic musculature of the mystacial pad. Results showed that hypoglossal neurons also innervate the masseter muscle. Dil injected into the XII nucleus showed hypoglossal axons in the ipsilateral main trunk of the trigeminal nerve. After Gasser's ganglion crossing, the axons entered into the infraorbital division of the trigeminal nerve and targeted the extrinsic muscles of the mystacial pad. They also spread into the masseter branch of the trigeminal nerve to target the polar portions of the masseter muscle spindles. Retrograde double labelling, performed by injecting Dil into the pad and True Blue into the ipsilateral masseter muscle, showed labelled hypoglossal neurons in the medio-dorsal portion of the XII nucleus. The majority of these neurons were small (15-20 microm diameter), showed fluorescence for Dil and projected to the mystacial pad. Other medium-size neurons (25 microm diameter) were instead labelled with True Blue and projected to the masseter muscle. Finally, in the same area, other small hypoglossal neurons showed double labelling and projected to both structures. Functional hypotheses on the role of these hypoglossal projections have been discussed.

  18. [Lateral motor nucleus in the lumbosacral segment of the spinal cord of the horse].

    PubMed

    Flieger, S; Sławomirski, J; Boratyński, Z; Jastrzebski, M

    1984-01-01

    Two medullae oblongatae of horses were cut into 15 microns cross-sections and stained according to the modified method of Nissel. The lateral motor nucleus lies in the lateral and median part of the ventral column of spinal cord grey matter. It adjoins medially nucleus motorius medialis of the spinal ventral column. Cells of this nucleus occur both along the whole lumbar and sacral segment of the spinal cord. In the lateral motor nucleus three cell groups are distinguished - median, basal and lateral. The latter is divided in some segments into subgroups - dorsal and ventral. Along the nucleus quite numerous constrictions and intervals are found, which are caused by various numbers of cells in particular cross-sections. Nucleus motorius lateralis is formed mainly of large and medium multipolar or single spindle cells.

  19. [Nucleus motorius lateralis in the lumbosacral segment of the spinal cord in horses].

    PubMed

    Flieger, S; Sławomirski, J; Boratyński, Z; Jastrzebski, M

    1984-01-01

    Two medullae oblongatae of horses were cut into 15 microns cross-sections and stained according to the modified method of Nissel. The lateral motor nucleus lies in the lateral and median part of the ventral column of spinal cord grey matter. It adjoins medially nucleus motorius medialis of the spinal ventral column. Cells of this nucleus occur both along the whole lumbar and sacral segment of the spinal cord. In the lateral motor nucleus three cell groups are distinguished-median, basal and lateral. The latter is divided in some segments into subgroups-dorsal and ventral. Along the nucleus quite numerous constrictions and intervals are found, which are caused by various numbers of cells in particular cross-sections. Nucleus motorius lateralis is formed mainly of large and medium multipolar or single spindle cells.

  20. Selective Stimulation and Measurement in the Cochlear Nucleus With the Spike Microelectrode Array

    DTIC Science & Technology

    2007-11-02

    Selective Stimulation and Measurement in the Cochlear Nucleus with the Spike Microelectrode Array F. MASE1, H. TAKAHASHI1, T. EJIRI1, M. NAKAO1, N...aren’t always effective, because we don’t have sufficient knowledge of the auditory pathways and the Cochlear Nucleus (CN) functions to stimulate the... Cochlear Nucleus functionally. Our goals are to enhance our understanding of such functions and to develop effective stimulating strategies of the CN